Energy Usage in the United States Renewable . Energy [ill ENERGY AND POWER A review of the customary units used for energy and power is appropriate to initi- ate a study of alternative energy sources and applications. Although much of the world uses the SI system (Systeme international d'unites), the United States, in addi- tion to the SI system, uses the English Engineering and the British Gravitational sys- tems of units. The unit of energy in the SI system is the N-m (newton-meter), which is also defined as the joule (J). Energy in the English Engineering (EE) system is defined as the Btu (British thermal unit), or alternatively, the ft-Ibf (foot-pound force). Power is the rate of energy usage or transfer in J/sec, Btu/sec, or ft-lbflsec. Power equal to 1 J/sec is defined as a watt (W). The most frequently used power unit is kilowatt (kW), or 1000 W In the United States, power is sometimes expressed in terms of horsepower (hp), where 1 hp is 550 ft-lbf/sec or 0.7457 kW The kilowatt- hour (kWh) is another frequently used unit of energy and represents a unit of energy (kW) multiplied by a unit of time (hour). The conversion is 3412.14 Btu = 1 kWh. Tester et aL (2005) provide a sampling of power expenditures for various activ- ities. Some of their results are reproduced as Table 1.1. The range of power expended is astonishing, about 9 orders of magnitude. 1m ENERGY USAGE AND STANDARD OF LIVING An irrefutable fact is that the developed countries (the United States, Japan, the United Kingdom, etc.) use more energy per capita than the less developed countries (Mexico, Indonesia, etc.). Figure 1.1 , taken from Tester et aL (2005), graphically pre- sents energy consumption per capita as a function of gross national product (G NP) per capita for a number of countries. For the industrialized countries, the GNP per capita is from $15,000 to $25,000 while the energy consumption per capita is from 1
Transcript
Energy Usage in the United States
Renewable Energy
[ill ENERGY AND POWER
A review of the customary units used for energy and power is appropriate to initishyate a study of alternative energy sources and applications Although much of the world uses the SI system (Systeme international dunites) the United States in addishytion to the SI system uses the English Engineering and the British Gravitational sysshytems of units The unit of energy in the SI system is the N-m (newton-meter) which is also defined as the joule (J) Energy in the English Engineering (EE) system is defined as the Btu (British thermal unit) or alternatively the ft-Ibf (foot-pound force) Power is the rate of energy usage or transfer in Jsec Btusec or ft-lbflsec Power equal to 1 Jsec is defined as a watt (W) The most frequently used power unit is kilowatt (kW) or 1000 W In the United States power is sometimes expressed in terms of horsepower (hp) where 1 hp is 550 ft-lbfsec or 07457 kW The kilowattshyhour (kWh) is another frequently used unit of energy and represents a unit of energy (kW) multiplied by a unit of time (hour) The conversion is 341214 Btu = 1 kWh
Tester et aL (2005) provide a sampling of power expenditures for various activshyities Some of their results are reproduced as Table 11 The range of power expended is astonishing about 9 orders of magnitude
1m ENERGY USAGE AND STANDARD OF LIVING
An irrefutable fact is that the developed countries (the United States Japan the United Kingdom etc) use more energy per capita than the less developed countries (Mexico Indonesia etc) Figure 11 taken from Tester et aL (2005) graphically preshysents energy consumption per capita as a function of gross national product (G NP) per capita for a number of countries For the industrialized countries the GNP per capita is from $15000 to $25000 while the energy consumption per capita is from
1
bull bull
2 Chapter 1 Energy Usage in the United States
TABLE 11 Power expenditures for various activities
Activity Power Expended
Pumping human heart Household light bulb Human hard work Draft horse Portable floor heater Compact automobile SUV Combustion turbine Large ocean liner Boeing 747 at cruise Coal-fired power plant Niagara Falls hydroelectric plant
150 OJ to 325 OJ The United States and Canada have the highest energy conshysumption per capita A number of reasons exist for the high energy consumption per capita in the United States among them (1) historically cheap energy (2) low popshyulation density (3) large area and (4) a history of abundant domestic energy
As discussed later in this chapter low energy costs and domestic energy abunshydance are a thing of the past and the United States faces escalating energy costs and
350
Canada USA300 - Q i9 250 ~
lttl bulllt-) Germany
Qj 200 bull Sweden a UK bullc
12 150 bull France 15- Oman bull
JapanE bull bullJ
bullen 100 Italyc 0
lt-) Israel raquo 50egt Q) c
UJ 0
0 5 10 15 20 25 30
GNP per Capita (US$) - (Thousands)
Figure 11 Per capita energy consumption versus gross national product (GNP) per capita for a number of countries (Tester et a 200S)
13 A Historical Perspective of Energy Usage in the United States 3
the need for increasing energy imports (chiefly in the form of oil) The long-term implications of growing energy costs and imports will dramatically affect both the economy and the foreign policy posture of the United States Indeed the basis of this textbook is the need to consider both alternative energy sources and alternative (read more efficient) energy applications to address the energy problems facing the United States
The energy problem in the United States is exacerbated by measures by other countries (India and China for example) to increase the standard of living for their citizens World energy consumption is rising faster than energy consumption in the United States
A HISTORICAL PERSPECTIVE OF ENERGY USAGE IN THE UNITED STATES
The Energy Information Administration (EIA) of the United States Department of Energy (USDOE) provides a readily accessible and up-to-date source of energy stashytistics The EIA website is wwweiadoegov The EIA provides on a timely basis yearly energy statistics for the United States These yearly energy summaries titled Annual Energy Review appear about eight months after the end of the calendar year and can be accessed at wwweiadoegovaerThe info rmation contained in this text is from calshyendar year 2007 and carries the USDOE accession number DOEEIA-0384 (2007)
Figure 12 a mosaic of nighttime sa tellite photographs of the United States is a rather dramatic illustration of the population density and dispers ion and of the popshyulation of the United States as well as the energy intensity distribution of night lightshying (primarily from electricity usage)
Figure 12 Mosaic of nighttime satellite photographs of the United States (ErA 2007)
Figure 13 Historical energy utilization in the United States (EIA 2008)
1975 2000
Consider how the United States arrived at its current energy economy Figure 13 taken from the EIA Annual Energy Review 2007 presents a graphical representashytion of historical energy utilization 111e energy unit used is the quad (equal to 1 quadrillion Btu = 1015 Btu) Until the mid-1800s energy utilization was mostly wood with coal becoming increasingly important after 1850 By 1900 coal usage was much greater than wood usage and petroleum was becoming more important as an energy source In 1950 petroleum usage exceeded coal usage and natural gas usage was drashymatically rising At the turn of the millennium petroleum provided the most energy with natural gas and coal vying for second and third place Nuclear power was in fourth place with hydroelectric and renewable energy (including wood) sources makshying the smallest contributions In the next section details of the energy utilization in 2007 will be explored
The genesis of the energy problem is illustrated in Figure 14 Until about 1950 the United States had little dependence on energy imports However with the
120shy
90shy
Ol
m c g 60shyt 0
Ol a 30shy
~ Exports - -----_ _------ - ~---o iii bull i iii i jj v------ 1950 1960 1970 1980 1990 2000
Figure 14 Energy consumption imports and exports for the United States
l3 Itashyo 1 od Jch rgy Irashyrgy in akshy1 in
)50 the
13 A Historical Perspective of Energy Usage in the United States 5
500shyPeak 359 in 1978 and 1979 337 in 2007
400- J ~----~ym300shyc Q
~2oo
214 in 1949 100shy
o i i i Iii i i i iii I i i U bullbull i i ii i 1950 1960 1970 1980 1990 2000
Figure 15 Historical per capita energy consumption in the United States
post-World War II prosperity energy exports began to increase as consumption outshypaced domestic production Since the 1980s domestic production has increased but at a rate slower than consumption has increased The result has been a steady increase in energy imports
Further explanation of how the United States arrived at its current rate of energy consumption is provided in Figures 15 and 16 Figure 15 tracks per capita energy consumption and Figure 16 displays energy use per dollar of gross domestic prodshyuct Per capita energy consumption peaked at 360 million Btu in 1978 and declined during the energy crisis of the 1970s and 1980s Some slight increases occurred durshying the 1990s and in 2007 the per capita energy consumption was 337 million Btu The energy crisis resulted in no dramatic decrease in per capita energy consumption in the United States these results explain in part the current energy dilemma of the United States In short the United States failed to understand and heed the warnshyings of the first energy crisis Figure 16 represents the energy usage per dollar of gross national product (GNP) Since the 1980s the energy consumed per dollar of GNP has meaningfully declined from nearly 18000 Btu to the 2007 value of 8780 Btu This decline is attributed to increased energy efficiency especially in manufacturing and to structural changes in the economy (the migration of much energy-intensive indusshytry to other countries)
25shy 17 99 in 1970
t 878 in 2007
o i i j bullbullbullbullbull I I iii i i i r i i i bullbull i i i i i Iii i i iii i i bull i i
1950 1960 1970 1980 1990 2000
Figure 16 Historical energy use per dollar of gross domestic product in the United States
6 Chapter 1 Energy Usage in the United States
[E] UNITED STATES ENERGY USAGE IN 2007
The EIA energy flow diagram from the Annual Energy Review 2007 is arguably the most informative graphical representation in the Review and is reproduced as Figure 17 In this figure all energy usages are in quads (10 15 Btu) Energy sources are delinshyeated on the left-hand side of the diagram (coal at 2348 quad for example) The sources are then summed and expressed in terms of domestic production (7171 quad) and imports (3460 quad) The total supply is 10696 quad with exports of 536 quad which yields 1016 quad for consumption TIms in 2007 the United States energy economy was 10696 quad of which 3460 quad was imported
The end-point energy usages (categorized as residential commercial industrial and transportation) are shown on the right-hand side of the figure They are also disshyplayed on a pie chart in Figure 18 Industrial usage accounts for 32 percent of the total energy used followed by 29 percent for transportation TI1e remainder is almost
(Quadrillion Btu)
Includes lease condensate I) Natural gas ~ant Uquids
Other Importse
590
C Conventional hydroelectric power biomass geothermal solarphOtavoltaic and wind d Cru de oil and petroleum products Indudes imports Into the Strategic Petroleum Reserve II Natural gas coal coal coke fuel ethanol and electricity Adjustments losses and unaccounted for e Coal natural gas coal coke and electricity ~ Natural gas only eXdudes supplemental gaseous fuels
Petroleum 293
I Petroleum product s including natural gas planlliquids and crude all burned as fuel InCludes 003 quadrillion Btu of coal coke net imports k Includes 011 quadrillion Btu of electrtdty net Imports bull Primary consumption electridty relat[ sales and electrical system energy losses w11lch are
allocated to the end-use seC10rs In proportion to each sectors share of lolal electridty retail sales See NOle -Electrical Systems Energy Lossesmiddot at end of section 2
Notes Data are preliminary bull Values are derived trom source data prior to rounding for publication bull Tolals may not equal sum of components due to Independent rounding
Sources Tables 11 12 13 14 and 2 1a
Energy Information Admlnlstratlon I Annual Energy Review 2007
Figure 17 United States energy flow diagram for 2007
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
bull bull
2 Chapter 1 Energy Usage in the United States
TABLE 11 Power expenditures for various activities
Activity Power Expended
Pumping human heart Household light bulb Human hard work Draft horse Portable floor heater Compact automobile SUV Combustion turbine Large ocean liner Boeing 747 at cruise Coal-fired power plant Niagara Falls hydroelectric plant
150 OJ to 325 OJ The United States and Canada have the highest energy conshysumption per capita A number of reasons exist for the high energy consumption per capita in the United States among them (1) historically cheap energy (2) low popshyulation density (3) large area and (4) a history of abundant domestic energy
As discussed later in this chapter low energy costs and domestic energy abunshydance are a thing of the past and the United States faces escalating energy costs and
350
Canada USA300 - Q i9 250 ~
lttl bulllt-) Germany
Qj 200 bull Sweden a UK bullc
12 150 bull France 15- Oman bull
JapanE bull bullJ
bullen 100 Italyc 0
lt-) Israel raquo 50egt Q) c
UJ 0
0 5 10 15 20 25 30
GNP per Capita (US$) - (Thousands)
Figure 11 Per capita energy consumption versus gross national product (GNP) per capita for a number of countries (Tester et a 200S)
13 A Historical Perspective of Energy Usage in the United States 3
the need for increasing energy imports (chiefly in the form of oil) The long-term implications of growing energy costs and imports will dramatically affect both the economy and the foreign policy posture of the United States Indeed the basis of this textbook is the need to consider both alternative energy sources and alternative (read more efficient) energy applications to address the energy problems facing the United States
The energy problem in the United States is exacerbated by measures by other countries (India and China for example) to increase the standard of living for their citizens World energy consumption is rising faster than energy consumption in the United States
A HISTORICAL PERSPECTIVE OF ENERGY USAGE IN THE UNITED STATES
The Energy Information Administration (EIA) of the United States Department of Energy (USDOE) provides a readily accessible and up-to-date source of energy stashytistics The EIA website is wwweiadoegov The EIA provides on a timely basis yearly energy statistics for the United States These yearly energy summaries titled Annual Energy Review appear about eight months after the end of the calendar year and can be accessed at wwweiadoegovaerThe info rmation contained in this text is from calshyendar year 2007 and carries the USDOE accession number DOEEIA-0384 (2007)
Figure 12 a mosaic of nighttime sa tellite photographs of the United States is a rather dramatic illustration of the population density and dispers ion and of the popshyulation of the United States as well as the energy intensity distribution of night lightshying (primarily from electricity usage)
Figure 12 Mosaic of nighttime satellite photographs of the United States (ErA 2007)
Figure 13 Historical energy utilization in the United States (EIA 2008)
1975 2000
Consider how the United States arrived at its current energy economy Figure 13 taken from the EIA Annual Energy Review 2007 presents a graphical representashytion of historical energy utilization 111e energy unit used is the quad (equal to 1 quadrillion Btu = 1015 Btu) Until the mid-1800s energy utilization was mostly wood with coal becoming increasingly important after 1850 By 1900 coal usage was much greater than wood usage and petroleum was becoming more important as an energy source In 1950 petroleum usage exceeded coal usage and natural gas usage was drashymatically rising At the turn of the millennium petroleum provided the most energy with natural gas and coal vying for second and third place Nuclear power was in fourth place with hydroelectric and renewable energy (including wood) sources makshying the smallest contributions In the next section details of the energy utilization in 2007 will be explored
The genesis of the energy problem is illustrated in Figure 14 Until about 1950 the United States had little dependence on energy imports However with the
120shy
90shy
Ol
m c g 60shyt 0
Ol a 30shy
~ Exports - -----_ _------ - ~---o iii bull i iii i jj v------ 1950 1960 1970 1980 1990 2000
Figure 14 Energy consumption imports and exports for the United States
l3 Itashyo 1 od Jch rgy Irashyrgy in akshy1 in
)50 the
13 A Historical Perspective of Energy Usage in the United States 5
500shyPeak 359 in 1978 and 1979 337 in 2007
400- J ~----~ym300shyc Q
~2oo
214 in 1949 100shy
o i i i Iii i i i iii I i i U bullbull i i ii i 1950 1960 1970 1980 1990 2000
Figure 15 Historical per capita energy consumption in the United States
post-World War II prosperity energy exports began to increase as consumption outshypaced domestic production Since the 1980s domestic production has increased but at a rate slower than consumption has increased The result has been a steady increase in energy imports
Further explanation of how the United States arrived at its current rate of energy consumption is provided in Figures 15 and 16 Figure 15 tracks per capita energy consumption and Figure 16 displays energy use per dollar of gross domestic prodshyuct Per capita energy consumption peaked at 360 million Btu in 1978 and declined during the energy crisis of the 1970s and 1980s Some slight increases occurred durshying the 1990s and in 2007 the per capita energy consumption was 337 million Btu The energy crisis resulted in no dramatic decrease in per capita energy consumption in the United States these results explain in part the current energy dilemma of the United States In short the United States failed to understand and heed the warnshyings of the first energy crisis Figure 16 represents the energy usage per dollar of gross national product (GNP) Since the 1980s the energy consumed per dollar of GNP has meaningfully declined from nearly 18000 Btu to the 2007 value of 8780 Btu This decline is attributed to increased energy efficiency especially in manufacturing and to structural changes in the economy (the migration of much energy-intensive indusshytry to other countries)
25shy 17 99 in 1970
t 878 in 2007
o i i j bullbullbullbullbull I I iii i i i r i i i bullbull i i i i i Iii i i iii i i bull i i
1950 1960 1970 1980 1990 2000
Figure 16 Historical energy use per dollar of gross domestic product in the United States
6 Chapter 1 Energy Usage in the United States
[E] UNITED STATES ENERGY USAGE IN 2007
The EIA energy flow diagram from the Annual Energy Review 2007 is arguably the most informative graphical representation in the Review and is reproduced as Figure 17 In this figure all energy usages are in quads (10 15 Btu) Energy sources are delinshyeated on the left-hand side of the diagram (coal at 2348 quad for example) The sources are then summed and expressed in terms of domestic production (7171 quad) and imports (3460 quad) The total supply is 10696 quad with exports of 536 quad which yields 1016 quad for consumption TIms in 2007 the United States energy economy was 10696 quad of which 3460 quad was imported
The end-point energy usages (categorized as residential commercial industrial and transportation) are shown on the right-hand side of the figure They are also disshyplayed on a pie chart in Figure 18 Industrial usage accounts for 32 percent of the total energy used followed by 29 percent for transportation TI1e remainder is almost
(Quadrillion Btu)
Includes lease condensate I) Natural gas ~ant Uquids
Other Importse
590
C Conventional hydroelectric power biomass geothermal solarphOtavoltaic and wind d Cru de oil and petroleum products Indudes imports Into the Strategic Petroleum Reserve II Natural gas coal coal coke fuel ethanol and electricity Adjustments losses and unaccounted for e Coal natural gas coal coke and electricity ~ Natural gas only eXdudes supplemental gaseous fuels
Petroleum 293
I Petroleum product s including natural gas planlliquids and crude all burned as fuel InCludes 003 quadrillion Btu of coal coke net imports k Includes 011 quadrillion Btu of electrtdty net Imports bull Primary consumption electridty relat[ sales and electrical system energy losses w11lch are
allocated to the end-use seC10rs In proportion to each sectors share of lolal electridty retail sales See NOle -Electrical Systems Energy Lossesmiddot at end of section 2
Notes Data are preliminary bull Values are derived trom source data prior to rounding for publication bull Tolals may not equal sum of components due to Independent rounding
Sources Tables 11 12 13 14 and 2 1a
Energy Information Admlnlstratlon I Annual Energy Review 2007
Figure 17 United States energy flow diagram for 2007
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
13 A Historical Perspective of Energy Usage in the United States 3
the need for increasing energy imports (chiefly in the form of oil) The long-term implications of growing energy costs and imports will dramatically affect both the economy and the foreign policy posture of the United States Indeed the basis of this textbook is the need to consider both alternative energy sources and alternative (read more efficient) energy applications to address the energy problems facing the United States
The energy problem in the United States is exacerbated by measures by other countries (India and China for example) to increase the standard of living for their citizens World energy consumption is rising faster than energy consumption in the United States
A HISTORICAL PERSPECTIVE OF ENERGY USAGE IN THE UNITED STATES
The Energy Information Administration (EIA) of the United States Department of Energy (USDOE) provides a readily accessible and up-to-date source of energy stashytistics The EIA website is wwweiadoegov The EIA provides on a timely basis yearly energy statistics for the United States These yearly energy summaries titled Annual Energy Review appear about eight months after the end of the calendar year and can be accessed at wwweiadoegovaerThe info rmation contained in this text is from calshyendar year 2007 and carries the USDOE accession number DOEEIA-0384 (2007)
Figure 12 a mosaic of nighttime sa tellite photographs of the United States is a rather dramatic illustration of the population density and dispers ion and of the popshyulation of the United States as well as the energy intensity distribution of night lightshying (primarily from electricity usage)
Figure 12 Mosaic of nighttime satellite photographs of the United States (ErA 2007)
Figure 13 Historical energy utilization in the United States (EIA 2008)
1975 2000
Consider how the United States arrived at its current energy economy Figure 13 taken from the EIA Annual Energy Review 2007 presents a graphical representashytion of historical energy utilization 111e energy unit used is the quad (equal to 1 quadrillion Btu = 1015 Btu) Until the mid-1800s energy utilization was mostly wood with coal becoming increasingly important after 1850 By 1900 coal usage was much greater than wood usage and petroleum was becoming more important as an energy source In 1950 petroleum usage exceeded coal usage and natural gas usage was drashymatically rising At the turn of the millennium petroleum provided the most energy with natural gas and coal vying for second and third place Nuclear power was in fourth place with hydroelectric and renewable energy (including wood) sources makshying the smallest contributions In the next section details of the energy utilization in 2007 will be explored
The genesis of the energy problem is illustrated in Figure 14 Until about 1950 the United States had little dependence on energy imports However with the
120shy
90shy
Ol
m c g 60shyt 0
Ol a 30shy
~ Exports - -----_ _------ - ~---o iii bull i iii i jj v------ 1950 1960 1970 1980 1990 2000
Figure 14 Energy consumption imports and exports for the United States
l3 Itashyo 1 od Jch rgy Irashyrgy in akshy1 in
)50 the
13 A Historical Perspective of Energy Usage in the United States 5
500shyPeak 359 in 1978 and 1979 337 in 2007
400- J ~----~ym300shyc Q
~2oo
214 in 1949 100shy
o i i i Iii i i i iii I i i U bullbull i i ii i 1950 1960 1970 1980 1990 2000
Figure 15 Historical per capita energy consumption in the United States
post-World War II prosperity energy exports began to increase as consumption outshypaced domestic production Since the 1980s domestic production has increased but at a rate slower than consumption has increased The result has been a steady increase in energy imports
Further explanation of how the United States arrived at its current rate of energy consumption is provided in Figures 15 and 16 Figure 15 tracks per capita energy consumption and Figure 16 displays energy use per dollar of gross domestic prodshyuct Per capita energy consumption peaked at 360 million Btu in 1978 and declined during the energy crisis of the 1970s and 1980s Some slight increases occurred durshying the 1990s and in 2007 the per capita energy consumption was 337 million Btu The energy crisis resulted in no dramatic decrease in per capita energy consumption in the United States these results explain in part the current energy dilemma of the United States In short the United States failed to understand and heed the warnshyings of the first energy crisis Figure 16 represents the energy usage per dollar of gross national product (GNP) Since the 1980s the energy consumed per dollar of GNP has meaningfully declined from nearly 18000 Btu to the 2007 value of 8780 Btu This decline is attributed to increased energy efficiency especially in manufacturing and to structural changes in the economy (the migration of much energy-intensive indusshytry to other countries)
25shy 17 99 in 1970
t 878 in 2007
o i i j bullbullbullbullbull I I iii i i i r i i i bullbull i i i i i Iii i i iii i i bull i i
1950 1960 1970 1980 1990 2000
Figure 16 Historical energy use per dollar of gross domestic product in the United States
6 Chapter 1 Energy Usage in the United States
[E] UNITED STATES ENERGY USAGE IN 2007
The EIA energy flow diagram from the Annual Energy Review 2007 is arguably the most informative graphical representation in the Review and is reproduced as Figure 17 In this figure all energy usages are in quads (10 15 Btu) Energy sources are delinshyeated on the left-hand side of the diagram (coal at 2348 quad for example) The sources are then summed and expressed in terms of domestic production (7171 quad) and imports (3460 quad) The total supply is 10696 quad with exports of 536 quad which yields 1016 quad for consumption TIms in 2007 the United States energy economy was 10696 quad of which 3460 quad was imported
The end-point energy usages (categorized as residential commercial industrial and transportation) are shown on the right-hand side of the figure They are also disshyplayed on a pie chart in Figure 18 Industrial usage accounts for 32 percent of the total energy used followed by 29 percent for transportation TI1e remainder is almost
(Quadrillion Btu)
Includes lease condensate I) Natural gas ~ant Uquids
Other Importse
590
C Conventional hydroelectric power biomass geothermal solarphOtavoltaic and wind d Cru de oil and petroleum products Indudes imports Into the Strategic Petroleum Reserve II Natural gas coal coal coke fuel ethanol and electricity Adjustments losses and unaccounted for e Coal natural gas coal coke and electricity ~ Natural gas only eXdudes supplemental gaseous fuels
Petroleum 293
I Petroleum product s including natural gas planlliquids and crude all burned as fuel InCludes 003 quadrillion Btu of coal coke net imports k Includes 011 quadrillion Btu of electrtdty net Imports bull Primary consumption electridty relat[ sales and electrical system energy losses w11lch are
allocated to the end-use seC10rs In proportion to each sectors share of lolal electridty retail sales See NOle -Electrical Systems Energy Lossesmiddot at end of section 2
Notes Data are preliminary bull Values are derived trom source data prior to rounding for publication bull Tolals may not equal sum of components due to Independent rounding
Sources Tables 11 12 13 14 and 2 1a
Energy Information Admlnlstratlon I Annual Energy Review 2007
Figure 17 United States energy flow diagram for 2007
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
Figure 13 Historical energy utilization in the United States (EIA 2008)
1975 2000
Consider how the United States arrived at its current energy economy Figure 13 taken from the EIA Annual Energy Review 2007 presents a graphical representashytion of historical energy utilization 111e energy unit used is the quad (equal to 1 quadrillion Btu = 1015 Btu) Until the mid-1800s energy utilization was mostly wood with coal becoming increasingly important after 1850 By 1900 coal usage was much greater than wood usage and petroleum was becoming more important as an energy source In 1950 petroleum usage exceeded coal usage and natural gas usage was drashymatically rising At the turn of the millennium petroleum provided the most energy with natural gas and coal vying for second and third place Nuclear power was in fourth place with hydroelectric and renewable energy (including wood) sources makshying the smallest contributions In the next section details of the energy utilization in 2007 will be explored
The genesis of the energy problem is illustrated in Figure 14 Until about 1950 the United States had little dependence on energy imports However with the
120shy
90shy
Ol
m c g 60shyt 0
Ol a 30shy
~ Exports - -----_ _------ - ~---o iii bull i iii i jj v------ 1950 1960 1970 1980 1990 2000
Figure 14 Energy consumption imports and exports for the United States
l3 Itashyo 1 od Jch rgy Irashyrgy in akshy1 in
)50 the
13 A Historical Perspective of Energy Usage in the United States 5
500shyPeak 359 in 1978 and 1979 337 in 2007
400- J ~----~ym300shyc Q
~2oo
214 in 1949 100shy
o i i i Iii i i i iii I i i U bullbull i i ii i 1950 1960 1970 1980 1990 2000
Figure 15 Historical per capita energy consumption in the United States
post-World War II prosperity energy exports began to increase as consumption outshypaced domestic production Since the 1980s domestic production has increased but at a rate slower than consumption has increased The result has been a steady increase in energy imports
Further explanation of how the United States arrived at its current rate of energy consumption is provided in Figures 15 and 16 Figure 15 tracks per capita energy consumption and Figure 16 displays energy use per dollar of gross domestic prodshyuct Per capita energy consumption peaked at 360 million Btu in 1978 and declined during the energy crisis of the 1970s and 1980s Some slight increases occurred durshying the 1990s and in 2007 the per capita energy consumption was 337 million Btu The energy crisis resulted in no dramatic decrease in per capita energy consumption in the United States these results explain in part the current energy dilemma of the United States In short the United States failed to understand and heed the warnshyings of the first energy crisis Figure 16 represents the energy usage per dollar of gross national product (GNP) Since the 1980s the energy consumed per dollar of GNP has meaningfully declined from nearly 18000 Btu to the 2007 value of 8780 Btu This decline is attributed to increased energy efficiency especially in manufacturing and to structural changes in the economy (the migration of much energy-intensive indusshytry to other countries)
25shy 17 99 in 1970
t 878 in 2007
o i i j bullbullbullbullbull I I iii i i i r i i i bullbull i i i i i Iii i i iii i i bull i i
1950 1960 1970 1980 1990 2000
Figure 16 Historical energy use per dollar of gross domestic product in the United States
6 Chapter 1 Energy Usage in the United States
[E] UNITED STATES ENERGY USAGE IN 2007
The EIA energy flow diagram from the Annual Energy Review 2007 is arguably the most informative graphical representation in the Review and is reproduced as Figure 17 In this figure all energy usages are in quads (10 15 Btu) Energy sources are delinshyeated on the left-hand side of the diagram (coal at 2348 quad for example) The sources are then summed and expressed in terms of domestic production (7171 quad) and imports (3460 quad) The total supply is 10696 quad with exports of 536 quad which yields 1016 quad for consumption TIms in 2007 the United States energy economy was 10696 quad of which 3460 quad was imported
The end-point energy usages (categorized as residential commercial industrial and transportation) are shown on the right-hand side of the figure They are also disshyplayed on a pie chart in Figure 18 Industrial usage accounts for 32 percent of the total energy used followed by 29 percent for transportation TI1e remainder is almost
(Quadrillion Btu)
Includes lease condensate I) Natural gas ~ant Uquids
Other Importse
590
C Conventional hydroelectric power biomass geothermal solarphOtavoltaic and wind d Cru de oil and petroleum products Indudes imports Into the Strategic Petroleum Reserve II Natural gas coal coal coke fuel ethanol and electricity Adjustments losses and unaccounted for e Coal natural gas coal coke and electricity ~ Natural gas only eXdudes supplemental gaseous fuels
Petroleum 293
I Petroleum product s including natural gas planlliquids and crude all burned as fuel InCludes 003 quadrillion Btu of coal coke net imports k Includes 011 quadrillion Btu of electrtdty net Imports bull Primary consumption electridty relat[ sales and electrical system energy losses w11lch are
allocated to the end-use seC10rs In proportion to each sectors share of lolal electridty retail sales See NOle -Electrical Systems Energy Lossesmiddot at end of section 2
Notes Data are preliminary bull Values are derived trom source data prior to rounding for publication bull Tolals may not equal sum of components due to Independent rounding
Sources Tables 11 12 13 14 and 2 1a
Energy Information Admlnlstratlon I Annual Energy Review 2007
Figure 17 United States energy flow diagram for 2007
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
l3 Itashyo 1 od Jch rgy Irashyrgy in akshy1 in
)50 the
13 A Historical Perspective of Energy Usage in the United States 5
500shyPeak 359 in 1978 and 1979 337 in 2007
400- J ~----~ym300shyc Q
~2oo
214 in 1949 100shy
o i i i Iii i i i iii I i i U bullbull i i ii i 1950 1960 1970 1980 1990 2000
Figure 15 Historical per capita energy consumption in the United States
post-World War II prosperity energy exports began to increase as consumption outshypaced domestic production Since the 1980s domestic production has increased but at a rate slower than consumption has increased The result has been a steady increase in energy imports
Further explanation of how the United States arrived at its current rate of energy consumption is provided in Figures 15 and 16 Figure 15 tracks per capita energy consumption and Figure 16 displays energy use per dollar of gross domestic prodshyuct Per capita energy consumption peaked at 360 million Btu in 1978 and declined during the energy crisis of the 1970s and 1980s Some slight increases occurred durshying the 1990s and in 2007 the per capita energy consumption was 337 million Btu The energy crisis resulted in no dramatic decrease in per capita energy consumption in the United States these results explain in part the current energy dilemma of the United States In short the United States failed to understand and heed the warnshyings of the first energy crisis Figure 16 represents the energy usage per dollar of gross national product (GNP) Since the 1980s the energy consumed per dollar of GNP has meaningfully declined from nearly 18000 Btu to the 2007 value of 8780 Btu This decline is attributed to increased energy efficiency especially in manufacturing and to structural changes in the economy (the migration of much energy-intensive indusshytry to other countries)
25shy 17 99 in 1970
t 878 in 2007
o i i j bullbullbullbullbull I I iii i i i r i i i bullbull i i i i i Iii i i iii i i bull i i
1950 1960 1970 1980 1990 2000
Figure 16 Historical energy use per dollar of gross domestic product in the United States
6 Chapter 1 Energy Usage in the United States
[E] UNITED STATES ENERGY USAGE IN 2007
The EIA energy flow diagram from the Annual Energy Review 2007 is arguably the most informative graphical representation in the Review and is reproduced as Figure 17 In this figure all energy usages are in quads (10 15 Btu) Energy sources are delinshyeated on the left-hand side of the diagram (coal at 2348 quad for example) The sources are then summed and expressed in terms of domestic production (7171 quad) and imports (3460 quad) The total supply is 10696 quad with exports of 536 quad which yields 1016 quad for consumption TIms in 2007 the United States energy economy was 10696 quad of which 3460 quad was imported
The end-point energy usages (categorized as residential commercial industrial and transportation) are shown on the right-hand side of the figure They are also disshyplayed on a pie chart in Figure 18 Industrial usage accounts for 32 percent of the total energy used followed by 29 percent for transportation TI1e remainder is almost
(Quadrillion Btu)
Includes lease condensate I) Natural gas ~ant Uquids
Other Importse
590
C Conventional hydroelectric power biomass geothermal solarphOtavoltaic and wind d Cru de oil and petroleum products Indudes imports Into the Strategic Petroleum Reserve II Natural gas coal coal coke fuel ethanol and electricity Adjustments losses and unaccounted for e Coal natural gas coal coke and electricity ~ Natural gas only eXdudes supplemental gaseous fuels
Petroleum 293
I Petroleum product s including natural gas planlliquids and crude all burned as fuel InCludes 003 quadrillion Btu of coal coke net imports k Includes 011 quadrillion Btu of electrtdty net Imports bull Primary consumption electridty relat[ sales and electrical system energy losses w11lch are
allocated to the end-use seC10rs In proportion to each sectors share of lolal electridty retail sales See NOle -Electrical Systems Energy Lossesmiddot at end of section 2
Notes Data are preliminary bull Values are derived trom source data prior to rounding for publication bull Tolals may not equal sum of components due to Independent rounding
Sources Tables 11 12 13 14 and 2 1a
Energy Information Admlnlstratlon I Annual Energy Review 2007
Figure 17 United States energy flow diagram for 2007
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
6 Chapter 1 Energy Usage in the United States
[E] UNITED STATES ENERGY USAGE IN 2007
The EIA energy flow diagram from the Annual Energy Review 2007 is arguably the most informative graphical representation in the Review and is reproduced as Figure 17 In this figure all energy usages are in quads (10 15 Btu) Energy sources are delinshyeated on the left-hand side of the diagram (coal at 2348 quad for example) The sources are then summed and expressed in terms of domestic production (7171 quad) and imports (3460 quad) The total supply is 10696 quad with exports of 536 quad which yields 1016 quad for consumption TIms in 2007 the United States energy economy was 10696 quad of which 3460 quad was imported
The end-point energy usages (categorized as residential commercial industrial and transportation) are shown on the right-hand side of the figure They are also disshyplayed on a pie chart in Figure 18 Industrial usage accounts for 32 percent of the total energy used followed by 29 percent for transportation TI1e remainder is almost
(Quadrillion Btu)
Includes lease condensate I) Natural gas ~ant Uquids
Other Importse
590
C Conventional hydroelectric power biomass geothermal solarphOtavoltaic and wind d Cru de oil and petroleum products Indudes imports Into the Strategic Petroleum Reserve II Natural gas coal coal coke fuel ethanol and electricity Adjustments losses and unaccounted for e Coal natural gas coal coke and electricity ~ Natural gas only eXdudes supplemental gaseous fuels
Petroleum 293
I Petroleum product s including natural gas planlliquids and crude all burned as fuel InCludes 003 quadrillion Btu of coal coke net imports k Includes 011 quadrillion Btu of electrtdty net Imports bull Primary consumption electridty relat[ sales and electrical system energy losses w11lch are
allocated to the end-use seC10rs In proportion to each sectors share of lolal electridty retail sales See NOle -Electrical Systems Energy Lossesmiddot at end of section 2
Notes Data are preliminary bull Values are derived trom source data prior to rounding for publication bull Tolals may not equal sum of components due to Independent rounding
Sources Tables 11 12 13 14 and 2 1a
Energy Information Admlnlstratlon I Annual Energy Review 2007
Figure 17 United States energy flow diagram for 2007
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
14 United States Energy Usage in 2007 7
he LIe
10shy
he 71 36 tes
al lisshyhe )st
which ere ietty retail
Jnding for
Commercial
Figure 18 End-use energy utilization in 2007
evenly split between residential and commercial Because no end-use sector domishynates the energy usage alternative sources and applications are needed for all endshyuse sectors if significant reductions in energy usage are to be forthcoming
In 2007 renewable energy from all sources amounted to about 7 percent of the total energy utilized in the United States Figure 19 itemizes the contribution of
SolarlPV 1
Wind 5
Geothermal 5
Waste 6
Nuclear Electric Biofuels 15 Power
Wood 32
Hydroelectric Power
36
lMunicipal solid waste
Figure 19 Percentage contributions of Fuel ethanol and biodiesel 3Conventional hydroelectric
renewable energy sources in 2007 power
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
8 Chapter 1 Energy Usage in the United States
(Million Barrels per Day)
Crude on Rorll1ety
and atender
N~J~
bull Unfinished oils other hydrocarbonslhydrogen and motor gasoline and aviation gasoline blending components b Net imports (141) end adjustments (-O05) minus stock change (002) and product supplied (003) Finished petroleum products liquefied petroleum gases and pentanes plus d Natural gas plant liquids
Refined ProductsC Exports
1 28 Refined ProductsC
Stock Change 014
~~~ 422
pek=d - -2-08 shyJrFOOr1 62
~~ - o)i OtIlsrU6
o Production minus refinery Inpul Noles bull Oata are preliminary bull Values are derived from source data prior 10 rounding for publication bull Totals may not equal sum of components due to independent rounding Sources Tables 51 53 55 56 511 513a-S13d 516 and Perroeum Supply Monfhly February 2008 Table 4
Figure 110 Uoited States petroleum flow diagram for 2007
renewable energy sources in the United States for 2007 Perhaps the most amazing statistic is that wood and conventional hydroelectric power accounted for 73 percent of the total renewable energy that year Solar and wind contributed only 5 percent of the total renewable energy (or just 035 percent of the total consumption) in 2007 Hence in spite of much interest and media hype the penetration of solar and wind energy into the energy mix has not made much progress
Figure 110 is a diagram of petroleum flow in the United States for 2007 The format of Figure 110 is similar to that of Figure 17 except that the numbers in the petroleum flow diagram are in millions of barrels per day (MMBD) Starting at the left-hand side domestic crude oil production is a little more than half the amount of crude oil imported The refinery output is expressed in terms of motor gasoline disshytillate fuel oil liquefied petroleum gases jet fuel residual fuel oil and other Motor gasoline at 929 MMBD accounted for nearly one-half of the total utilization of petroleum products in the United States in 2007 The right-hand side of the petroshyleum flow diagram expresses the end-point petroleum energy usages Transportation accounts for 69 percent of the total petroleum usage Industrial usage is about 25 pershycent with residential commercial and electric power generation responsible for the remaining 9 percent
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
ling for
~onlhfy
ing ent ent 07 ind
lle the the t of jisshy-tor
of 10shy
ion ershythe
14 United States Energy Usage in 2007 9
300shy$285 in 2007 ~
(Nominal)
225shy
L
~ 150shy~ I-~
(5 -~ Jl
o 075- Nominal
0 00 iii iii iii iii ii i i I
1980 1985 1990 1995 2000 2005
Chained dollars basis year of 2000 2Actual cost for a given year
Figure 111 Motor gasoline prices from 1978 to 2007
Transportation the dominant end-point petroleum energy usage warrants furshyther examination Much insight can be gained by tracking the cost of a gallon of motor gasoline in terms of real and nominal dollars Real dollars are the chained dollars based on the dollar in 2000 whereas nominal dollars represent the actual cost during a given year Real dollars thus account for inflation Figure 111 shows the real and nominal cost of a gallon of motor gasoline from 1978 to 2007 In real dollars gasoshyline was $225gallon in 1980 a price not reached again until 2004 As of the summer of 2008 gasoline was more than $400gallon reflecting the disturbingly rapid increase since 2004 Indeed only since 2000 has th e rate of increase of the price of gasoline exceeded that of inflation During the prosperous years of the 1990s relative to inflashytion gasoline prices declined No wonder conservation higher-gas-mileage vehicles and alternative sources failed to arouse much interest in the pUblic
The natural gas flow diagram for 2007 is presented in Figure 112 Natural gas usage in this figure is expressed in trillions of cubic feet As with the other energy flow diagrams (Figures 17 and 110) information proceeds from the left-hand side (sources) to the right-hand side (end-point usages) Imports account for about 18 pershycent of total consumption Industrial usage and electric power generation account for 64 percent of th e total na tural gas utilization with the remainder split between residential commercial and transportation
The coal flow diagram for 2007 is shown in Figure 113 and usage is expressed in millions of short tons In a fashion similar to the other energy flow diagrams (Figures 17 110 and 112) information proceeds from the left-hand side (sources) to the right-h and side (end-point usages) All coal is produced domestically with a small amount exported Virtually all of the coal usage (93 percent) in the United States is for the generation of electricity with some about 8 percent used in industrial
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
10 Chapter 1 Energy Usage In the United States
(Trillion Cubic Feet)
Vented and Flared 012
Repressuring 357
~ 1928
-pIlOn 2305 InduJb1aI
780
Ii Quantities lost and imbalances In data due to differences among data sources tI Natural gas consumed In the operation of pipelines (primarily in compressors) and as fuel in the delivery of natural gas 10 consumers plus a small quantity used as vehicle fuel
Noles bull Oata are preliminary bull Values are derived from source data prior to rounding for publication bull Totals may no equal sum of components due 10 independent rounding Sources Tables 61 62 and 65
Figure 112 United States natural gas flow diagram for 2007
(Million Short Tons)
iSurface 7943
1
1Bituminous
Coal 534 0
+--r-
Anthracite 16
Supplied 1
141
Imports 363
and Unaccounted
for 55
ReSi~ntia(0
Commercial 30
Indudes fina coal coal obtained from a refuse bank or slUrry dam anthracite culm bitumi- Notes Production categories are estimated other data are preliminary bull Values are nous gob and lignite waste that are consumed by the eledr1c power industrial sedors derived from source data prior to rounding for publication bull Totals may nol equal sum of
componenlS due 10 Independent rounding Sources Tables 71 72 and 73
Figure 113 United States coal flow diagram for 2007
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
14 United States Energy Usage in 2007 11
(Quadrillion Btu)
I j b 065
Ge~if[)nC01 Electrielty
r Otherb
lmiddot
lunding for 017 Unaccounted ford
032
t Net
Ger~laUon of~cify
141
l
Fossil Fuelamp 2959
COIIII6Iamp100 Losses 21 15
EnergyConsuJlilaquoj
To Generale Elm~ty
trial 2
Blast fumace gas propane gas and other manufactured and waste gases deri ed from r Transmission and distribution losses (electriCity losses that occur between the point of fossil fuels generation end delivery to the customer) are estimated as g percent of gross generation
D Batteries cnemicals hydrogen pitCh purchased steam sulfur miscellaneous leennalogies g Use of electricity that is 1) selfgenerated 2) produced by 9ilher the same entity thai and non-renewable wasle (municipal solid wasla from non-biogenic sources and lire-deriled consumes the power or an affiliate and 3) used in direct su pport of a service or Industrial fuels) process located within the same facility or group of facilities thai house the generating equipshy
e ESlimated as net generation divided by 095 ment Direct use is exclusive of station use d Data collection frame differences and nonsampling error Derived for the diagram by Notes bull Data are preliminary bull See Note Electrical System Energy Losses~ at the
subtracting Ihe ~ amp D Losses estimate from T amp 0 Losses and Unaccounted for- derived from end of Section 2 bull Values are derived from source data prior to rounding for publication bull Totals may not equal sum of components due to independent rounding Table 8L
Sources Tables 81 84a 89 and A6 (column 4) Electric energy used in the operation of power pfants estimated as 5 pereanl of gross generation
Figure 114 United States electricity flow diagram for 2007
applications Coal is the one energy source that the United States does not have to import However the extensive use of coal for electric generation poses significant environmental problems
Although an end-point energy use rather than an energy source an examinashytion of the electricity flow in the United States is appropriate Figure 114 presents the electricity flow diagram for 2007 the numbers in the figure are in quads (1015
Values are lual sum of
Btu) The conversion factor is 3412 Btu = 1 kWh The left-hand side delineates the input energy including nuclear electric power Coal is the dominant (71 percent) fosshysil fuel source of energy for electricity generation in the United States The right-hand side of the diagram breaks down the end-point energy usages including transmisshysion and distribution losses (about 9 percent) With 4209 quad consumed to genershyate 1494 quad of electricity the overall thermal efficiency of electricity generation is 35 percent Hence of the 4209 quad of energy used to generate electricity in the United States in 20072715 quad represents conversion losses
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
12 Chapter 1 Energy Usage in the United States
J 0 c t co ~ Q ~ a c l c CD ()
12shy
10shy
6shy
4shy
j2-__ ___ ~
~~ ~
Real
Nominal --_1--
o I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I bullbull I I I I I i I I I
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Chained doliars basis year of 2000 2Actual cost lor a given year
Figure 115 Electricity prices from 1960 to 2007
In a fashion similar to Figure 111 Figure 11S tracks the real and nominal cos t (in cents) of 1 kWh of electricity from 1960 until 2007 Real cents are the chained cents based on the cent in 2000 whereas nominal cents are the actual cost during a given year In 1960 the real cos t of 1 kWh of electricity was about 8S cents comshypared to about 8 cents in 2007 Indeed except for a few years in the 1980s the real cost of 1 kWh has been less than in 1960 From 1980 until 1998 the real cos t of 1 kWh of electricity monotonically declined As with motor gasoline the declining real cost of electricity during the prosperous years of the 1990s relative to inflation provided no economic impetus for conservation or exploration of alternative sources
rm WORLDWIDE ENERGY USE
Although this chapter concentrates on the energy scenario in the United States an examination of energy usage on a worldwide basis will enhance understanding of the global nature of the energy problem Figure 116 shows the energy utilization for the world and for the countries with the highest energy consumption from 1996 to 200S All data are presented in quads The increases in energy use worldwide and by China are evident in the figure The energy usage in Russia declined slightly and energy usage by the United States increased but not as rapidly as for China The energy problems of the United States are exacerbated by the increasing demand for energy worldwide and especially in countries with rapidly expanding economies
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
16 Efficiencies 13
500 shy
t d a 1shy
il h t
d
n e e )
a y y y
World 400
J
iii 300 shye pound C 0 co J 200shya
United States 100
China bull _ - bullbullbullbullbullbull ~ussiaO i i
1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Figure 116 World energy utilization from 1996 to 2005
EFFICIENCIES
The usual definition of the thermal efficiency of a heat engine is
Powerout TJ= (1-1)
Powerin
The following three consequences of the Second Law of Thermodynamics are useful for assigning limits to the efficiency of a heat engine
1 No heat engine can be more efficient than an externally reversible engine opershyating between the same temperature limits
2 All externally reversible heat engines operating between the same temperature limits have the same efficiency
3 The efficiency of any externally reversible heat engine operating between temshyperatures of TH (high temperature) and h (low temperature) is given by the Carnot efficiency
(1-2)
The Carnot efficiency TJCarnot thus provides a bound on the maximum efficiency that can be obtained by any heat engine
Tester et al (2005) provide a useful summary of typical efficiencies for a numshyber of components and devices associated with energy use Table 12 adapted from Tester et al (2005) presents the efficiency ranges for a number of energy system comshyponents lighting sources and biological systems Additionally Table 12 indicates the energy conversion path for each entry For example for large gas turbines the energy
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
14 Chapter 1 Energy Usage in the United States
conversion path is chemical to mechanical (c-cgtm) and the nominal efficiency range is 35-40 percent Some large components possess efficiencies above 90 percent but many widely used components-internal combustion engines for example-have efficiencies less than 30 percent From a historical perspective the reason for the demise of the steam locomotive is evident
Much of the electricity generated is used for lighting As Table 12 demonstrates even the most efficient lighting source high-pressure sodium is only 15-20 percent efficient Incandescent lighting is a woeful 2-5 percent efficient Biological systems used for food production-milk or beef for example-also exhibit low efficiencies Locally photosynthesis efficiency does not exceed 5 percent of the incident sunlight but the global mean is much lower
TABLE 12 Efficiencies of selected components and biological systems
Component Energy Conversion Path Efficiency (percent)
Large electric generators m-cgte 98-99 Large power plant boilers c-cgtt 90-98 Large electric motors e-cgtm 90-97 Home natural gas furnaces c-cgtt 90-96 Drycell batteries C-cgt e 85-95 Waterwheels (overshot) m-cgtm 60shy 85 Small electric motors e-cgtm 60-75 Large steam turbines t-cgtm 40-45 Wood stoves c-cgtt 25-45 Large gas turbines c-cgtm 35-40 Diesel engines c-cgtm 30-35 Photovoltaic cells r -cgt e 20-30 Large steam engines c-cgtm 20-25 Internal combustion engines c-cgtm 15-25 Steam locomotives c-cgtm 3-6
Light Sources High-pressure sodium lamps e -cgt r 15-20 Fluorescent lights e -cgt r 10-12 Incandescent light bulbs e-cgtr 2-5 Paraffin candles C-cgt r 1-2
Biological Systems Milk production C-cgt C 15-20 Broiler production c-cgtc 10-15 Beef production c-cgtc 5-10 Local photosynthesis r -cgt C 4-5 Global photosynthesis r -cgt C 03
Energy conversion path labels c =chemical e =electrical m =mechanical r = radiant l = thermal
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
~e
ut ve 1e
~S
nt ns ~s
1t
t)
References 15
What Table 12 ultimately indicates is that much engineering effort is needed to reduce energy utilization by improving the efficiencies of various components
] CLOSURE
The information in this chapter introduces the purpose of this book If we are to meet the increasing energy demands of the United States and the world the use of altershynative energy sources and alternative uses of existing energy sources must be conshysidered The remaining chapters examine fundamental principles and facts concerning a wide variety of alternative energy sources and alternative energy utiliza tion schemes The level of the coverage for a topic is in most instances fundamental To perform detailed engineering work on most topics represented in this book additional techshynicaJ information will be needed However the material presen ted herein provides an introduction to and overview of many alternative energy scenarios
R EVIE W QUESTIONS
1 What is a quad
2 What is the diffe rence between energy and power
3 What was the total energy usage in the United States in 2007
4 In 2007 in the United States what percentage of coal production was used to genshyerate electricity
5 How much renewable energy was used in the United States in 2007 What were the dominant sources of renewable energy
6 How much energy used in the United States in 2007 was imported
7 What has happened to United States energy imports since the 1970s
8 What does EIA stand for
9 In 2007 what percentages of US energy were used in residential commercial industrial and transportation applications
10 From 1980 through 1995 in terms of inflation-adjusted dollars what happened to the prices of gasoline and electricity
11 What has happened to world energy usage since the 1970s
12 What is the Carnot efficiency What is its importance
13 In comparison to most mechanical devices how efficient is photosynthesis
RE FERENCES
Energy Information Administration (EIA) 2008 Annual Energy Review 2007 Washington DC US Dept of Energy
Tester1 W Drake E M Driscoll M 1 Golay M W and Peters W A 2005 Sustainable Energy Cambridge MA MIT Press
