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UCRL-ID-129990-99
U.S. Energy Flow—1999
Gina V. Kaiper
March 2001
LawrenceLivermoreNationalLaboratory
U.S. Department of Energy
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UCRL-ID-129990-99
U.S. Energy Flow—1999
Gina V. Kaiper
March 2001
Contents• U.S. Energy Flow—1999 (chart in quads)• U.S. Energy Flow—1999 (in exajoules)• Notes on the U.S. Energy Flow Chart for
1999• Other Ways to View This Data• Comparison to 1997 and 1998• U.S. Energy Flow—1998 (flow chart, in
exajoules)• U.S. Energy Flow—1997 (flow chart in
quads)• Credits and Web Locations
March 2001Lawrence Livermore National Laboratory
U.S. Energy Flow – 1999Net Primary Resource Consumption 97 Quads
Source: Production and end-use data from Energy Information Administration, Annual Energy Review 1999*Biomass/other includes wood and waste, geothermal, solar, and wind.
3.24.6
4.5
20.7
Rejectedenergy
53.2
23.4Electrical systemenergy losses
2.2
5.2
1.0
Net Imports3.5
Imports
3.2
3.2
0.06
Nuclear 7.7
Export1.5
0.7
0.1
0.8
0.5
0.1
7.5
11.0Hydro 3.2
Biomass/other* 4.0
Net electrical imports 0.1
Bal. no. 0.3
Natural gas19.3
Electricitygeneration
34.4
Bal. no. 0.7
0.2
Coal23.3
19.3
Non–fuel6.6
Transpor-tation25.9
Distributedelectricity 11.1
Residential/Commercial
18.3
Industrial22.3
Export2.0
Bal. no. 2.1
3.6
0.02
3.2
0.1
4.64.5
20.7
Rejectedenergy
53.2
23.4
17.9
Usefulenergy
36.8
13.7
5.93.62.1
25.2
U.S. petroleumand NGPL 15.1
Imports 22.5
Electrical systemenergy losses
8.09.5
March 2001Lawrence Livermore National Laboratory
U.S. Energy Flow – 1999Net Primary Resource Consumption 102 Exajoules
Source: Production and end-use data from Energy Information Administration, Annual Energy Review 1999*Biomass/other includes wood and waste, geothermal, solar, and wind.
3.44.8
4.7
21.9
Rejectedenergy
56.1
24.7Electrical systemenergy losses
2.4
5.5
1.0
Net Imports3.7
Imports
3.4
3.3
0.06
Nuclear 8.2
Export1.6
0.7
0.1
0.8
0.6
0.1
8.0
11.6Hydro 3.3
Biomass/other* 4.2
Net electrical imports 0.1
Bal. no. 0.4
Natural gas20.4
Electricitygeneration
36.3
Bal. no. 0.7
0.2
Coal24.6
20.4
Non–fuel7.0
Transpor-tation27.3
Distributedelectricity 11.7
Residential/Commercial
19.3
Industrial23.6
Export2.1
Bal. no. 2.2
3.8
0.02
3.4
0.1
4.84.7
21.9
Rejectedenergy
56.1
24.7
18.8
Usefulenergy
38.8
14.5
6.23.82.2
26.6
U.S. petroleumand NGPL 15.9
Imports 23.8
Electrical systemenergy losses
8.510.0
U.S. Energy Flow—1999, page 3
Notes on the U.S. Energy Flow Chart for 1999
General Notes
BackgroundLawrence Livermore National Laboratory (LLNL) hasprepared similar flow charts of U.S. energy consumption since1972. The chart follows the flow of individual fuels andcompares these on the basis of a common energy unit ofquadrillion British thermal units (Btu). A quadrillion, or“quad,” is 1015. One Btu is the quantity of heat needed to raisethe temperature of 1 pound of water by 1°F at or near 39.2°F.
The width of each colored line across this chart is inproportion to the amount of quads conveyed. (Exception: linesshowing extremely small amounts have been made wideenough to be clearly visible.)
In most cases, the numbers used in this chart have beenrounded to the nearest tenth of a quad, although the originaldata was published in hundredths or thousandths of a quad.As a consequence of independent rounding, some of thesummary numbers may not appear to be a precise total oftheir various components.
The first chart in this document uses quadrillion Btu’s toconform with data from the U.S. Department of Energy’sEnergy Information Administration (EIA). However, thesecond chart is expressed in exajoules. A joule is the metricunit for heat. One Btu equals 1,055.06 joules; and onequadrillion Btu’s equals 1.055 exajoules (an exajoule is 1018
joules).
Data SourcesThe chart incorporates production and end-use data compiledby the Energy Information Administration, as published in theEIA’s Annual Energy Review 1999 [DOE/EIA-0384(99),Washington, D.C., July 2000]. This report is available on theWeb at http://www.eia.doe.gov/aer .
In the Annual Energy Review 1999 (AER99), summary data onenergy production, imports, exports, and consumption isprovided in Diagram 1, “Energy Flow, 1999” (p. 3) and Table1.1., “Energy Overview, 1949–1999” (p. 5). These show that96.60 quads of energy were consumed in the United States in1999.
Table 1.2, “Energy Production by Source, 1949–1999” (AER99,p. 7) gives additional details about the 72.523 quads of energyproduced within the United States.
Table 1.3, “Energy Consumption by Source, 1949–1999”(AER99, p. 9) indicates the amounts of various fossil fuels andrenewable energy sources consumed, as well as nuclearenergy.
Table 1.4, “Energy Imports, Exports, and Net Imports,1949–1999” (AER99, p. 11) shows that the United States hadnet energy imports of 23.10 quads in 1999. (Note that thisrepresents about 24% of total energy consumed and thatpetroleum accounts for about 89% of U.S. imported energy.)
U.S. Energy Flow—1999, page 4
Table 2.1, “Energy Consumption by End-Use Sector,1949–1999” (AER99, p. 37) gives the amounts and types ofenergy consumed by the three end-use sectors: (1)Residential/Commercial, (2) Industrial, and (3)Transportation.
End-Use SectorsThe Residential/Commercial sector includes private andinstitutional residences; business establishments not engagedin transportation or manufacturing; commercialestablishments; religious and nonprofit organizations; health,social, and educational institutions; and federal, state, andlocal governments. Electricity used for public street andhighway lighting is also included.
The Industrial sector includes manufacturing industries (thelargest part of the sector), mining, construction, agriculture,fisheries, and forestry. Establishments range from large steelmills to small farms. In LLNL’s energy flow chart, fossils fuelsused by industry in a non-fuel capacity have been treated as aseparate data stream; however, most of the AER99 tablesincorporate non-fuel consumption in the data for theindustrial sector.
The Transportation sector includes all types of public andprivate vehicles that transport people and commodities. Thissector also includes the energy used to transport natural gas inpipelines.
Energy ContentThe energy flow chart shows all energy streams in terms of acommon energy unit: quadrillion Btu. The EIA typically usesconversion factors that represent the gross heat content of thefuel, which is the total amount of heat released when fuel isburned (i.e., the “higher heating value”).
Appendix A of AER99 (pp. 327–337) gives the thermalconversion factors used in that report. These factors arecomputed annually from the best available data, weighted asappropriate. The heat content depends on source, type, year ofproduction, and use of fuel. For example, the relatively smallamount of coal consumed by the residential/commercialsector has an average heat content of approximately 22.783million Btu per short ton of coal, but the coal used to generateelectricity has an average heat content of approximately 20.479million Btu per short ton. (AER99, T. A5, p. 331).
Some conversion factors, useful for estimation, include:
Fuel Energy content (Btu)Short ton of coal 21,400,000Barrel (42 gallons) of crude oil 5,800,000Cubic foot of natural gas 1,027Kilowatt-hour of electricity 3,412
Conversion Efficiency FactorsFor the sake of consistency with LLNL’s previous energy flowcharts, the U.S. chart for 1999 assumes the same conversionefficiencies as in previous years to determine the proportion of“useful” to “rejected” energy.
For electricity generation, losses are assumed to be about two-thirds of the energy consumed. The energy flow chart for 1999shows “electrical system energy losses” of 23.4 quads, as givenin Table 2.1 of AER99 (p. 37). This includes the amount ofenergy lost during the generation, transmission, anddistribution of electricity, including plant and unaccounted-foruses (AER99, p. 357). Transmission and distribution losses,which are not spelled out separately on this chart, areestimated to be about 9% of the gross generation of electricity.
U.S. Energy Flow—1999, page 5
For the residential/commercial sector, we have again assumedan efficiency of 75%. This is a weighted average between spaceheating at approximately 60% efficiency and motors and otherelectrical uses at about 90% efficiency.
For the industrial sector, we have continued to assume aconversion efficiency of 80%.
For transportation, we assume a generous 20% efficiency,which corresponds to the approximate efficiency of theinternal combustion engines as measured on Federal DrivingSchedules.
Balancing NumbersFor visual clarity, the 1999 energy flow chart eliminates someof the smaller lines that appeared in previous versions (e.g.,storage, stocks, and strategic reserve amounts, as well as fielduse of natural gas.) Instead, three “balancing numbers” havebeen indicated, which together add about 1 quad of energybetween the left-hand (or “production”) side of the chart andthe right-hand (or “consumption”) side. This correspondsapproximately to the 0.98 quad “adjustments” amount givenin AER99 on Diagram 1 (p. 3) and Table 1.1 (p. 5).
Electricity GenerationLLNL’s earlier energy flow charts had separate lines for“utility consumption of electricity” and “cogeneration.” This1999 version does not distinguish between utility andnonutility generation.
The nonutility power producers include cogenerators whoprovide both electricity and steam or heat for industrial orother purposes. In addition, nonutility power producers
include small power producers (which use renewables for atleast 75% of their output) and independent power producers(which are unaffiliated with franchised utilities, do not possesstransmission facilities, and do not sell power in the retailservice area where they have a franchise).
Diagram 5 in AER99 (p. 209) shows the very complicatedelectricity flow of both electric utilities and nonutility powerproducers. This diagram shows net generation of 10.86 quadsby the utilities and 1.69 quads by the nonutility powerproducers—thus 13% of the net electricity generated in theUnited States in 1999 came from nonutility power producers.The nonutilities made direct use of 0.46 quads of thiselectricity but sold 0.85 quads to the utilities, where it becamepart of the 11.1 quads of electricity sold to the end-user sectors.
Nonfuel UseThe data on fossil fuel consumption for nonfuel use is fromAER, Table 1.15 (p. 33). Petroleum products account for 5.85quads of nonfuel use and include asphalt and road oil,liquefied petroleum gases, pentanes plus, lubricants,petrochemical feedstocks, special naphthas, and otherproducts.
Nonfuel consumption in 1999 accounted for 6.9% of theprimary energy resources consumed in the United States;however, because these resources were not used for energypurposes, LLNL’s energy flow chart does not assign “rejected”and “useful” designations.
U.S. Energy Flow—1999, page 6
Notes on Primary Resources
Biomass/OtherBy far the largest portion in this category comes from “woodand waste,” which accounted for 3.514 quads of energyproduced in 1999. Geothermal energy accounted for 0.327quads; solar for 0.076 quads; and wind for 0.038 quads.(AER99, Table 1.2, p. 7).
CoalIn 1999, coal represented almost a third of the energyproduced within the United States. About 90% of U.S. coalconsumption went for the generation of electricity and fueledabout 58% of the United States’ generation of electricity.
More details about the production and consumption of coalare given in AAER99 in Diagram 4 (p. 189) and Table 7.1(p. 191). The approximate heat content of coal is given in TableA5 (p. 331).
Hydroelectric PowerThis involves the production of power from falling water.Almost all of this energy goes for the generation of electricity,although a tiny fraction (about 0.1 quad) goes directly intoindustrial consumption.
Natural GasIn AER99, details about natural gas production andconsumption are included in Diagram 3 (p. 167) and Table 6.1(p. 169). The approximate heat content of natural gas is givenin Table A4 (p. 330).
Net imports of natural gas in 1999 amounted to 3.48 quadsand accounted for about 15.8% of the natural gas consumed in
the United States (AER99, Table 6.3, p. 173). About 94% of thegross natural gas imports came from Canada.
Of the natural gas withdrawn from U.S. wells in 1999, about22% came from offshore locations (AER99, Table 6.4, p 175).
Nuclear EnergyThis is generated by the 104 operable nuclear generating unitsin the United States. Nuclear energy accounted for 19.8% ofelectricity net generation in the United States in 1999 (AER99,Table 9.2, p. 247).
Petroleum and NGPLThis category includes both crude oil and natural gas plantliquids (i.e., hydrocarbons in natural gas that have beenseparated as liquids). In AER99, details about petroleum arefound in Diagram 2 (p. 117) and Tables 5.1 (p. 119). Theapproximate heat content of various petroleum products andof crude oil and NGPL can be found in AER99, Tables A1, A2,and A3 (pp. 327–329).
Petroleum, at 37.7 quads, accounted for 39% of the UnitedStates’ 1999 energy consumption. Motor gasoline was 43% ofthe total petroleum products supplied in 1999 (AER99, Fig.5.11, p. 138).
The net petroleum imports of 20.6 quads accounted for about55% of the 37.7 quads of petroleum consumed in 1999. Bycomparison, in 1990 only about 46% of petroleum consumedcame from imports. During that same interval (1990 to 1999),total U.S. energy consumption increased almost 15% (84.2quads to 96.6 quads), but petroleum consumption increasedonly about 12% (33.6 quads to 37.7 quads). (AER99, Tables 1.3and 1.4 )
U.S. Energy Flow—1999, page 7
Other Ways to View This Data
Rejected energy
55%
Useful energy
38%
The U.S. Consumed 96.6 Quads of Energy in 1999
Nonfuel use
7% Biomass and other
4.1%
Hydroelectric 3.5%
Petroleum
39%
Natural gas
22.8%
Coal
22.5%
Nuclear
8%
Source: AER99, Table 1.3
1999 Energy Consumption by Source
U.S. Energy Flow—1999, page 8
Industrial
(includes nonfuel use)
38%
Residential/Commercial
35%
Transportation
27%
1999 Energy Consumption by End-Use Sector
Source: AER99, Table 2.1
U.S. Energy Flow—1999, page 9
Comparison to 1997 and 1998
For comparison, the U.S. energy flow charts for 1997 and 1998are included in this document. The 1998 chart is in exajoulesinstead of quads. One quad equals 1.055 exajoules, so thenumbers on the 1998 chart are about 5.5% larger than if theywere given in quads.
The United States consumed 94.32 quads of energy in 1997and 94.57 quads in 1998, an increase of only 0.25%. In 1999,however, total U.S. energy consumption was 96.60 quads, anincrease of 2.1% over the previous year. (AER99, T1.1, p. 5.) Asshown below in Table 1, the largest growth occurred in thetransportation sector.
The numbers in the tables here are from AER99 and may havebeen revised since LLNL prepared the U.S. energy flow chartsfor 1997 and 1998.
Table 1. Energy consumption by end-use sector, 1997–1999.1997 1998 1999 Change
(quads) (quads) (quads) 1997–99
Residential/Commercial 33.64 33.68 34.17 1.6%
Industrial (incl.non-fuel) 35.85 35.54 36.50 1.8%
Transportation 24.82 25.36 25.92 4.4%
Total consumption 94.32 94.57 96.60 2.4%
Source: AER99, T. 2.1
Energy ImportsDuring those same three years, the amount of energyproduced in the United States remained almost constant, butthe net imports increased. As Table 2 indicates, petroleumaccounts for the majority of U.S. energy imports.
Table 2. U.S. energy production and imports, 1997–1999.1997 1998 1999 Change
(quads) (quads) (quads) 1997–99
U.S. production 72.532 72.550 72.523 (0.001%)
Net imports 20.94 22.51 23.10 10.3%
Net petroleumimports 19.64 20.94 20.57 4.7%
Source: AER99, T1.2 and 1.4
Resource ConsumptionVariations in resource consumption can be affected bydifferences in supply, cost, and weather. For example, theamount of rainfall in certain regions of the United Statesaffects the amount of hydroelectricity that can be produced.Colder winters increase the demand on fuels for space heating,while hotter summers lead to greater consumption ofelectricity and thus of the resources used in electricitygeneration.
U.S. Energy Flow—1999, page 10
Table 3. U.S. energy consumption by resource, 1997–1999.1997 1998 1999 Change
(quads) (quads) (quads) 1997–99
Biomass/other 3.418 3.432 3.956 15.7%
Hydro 3.940 3.552 3.417 (13.3%)
Nuclear 6.678 7.157 7.733 15.8%
Natural gas 22.530 21.921 22.096 (1.9%)
Coal* 21.490 21.660 21.756 1.2%
Petroleum &NGPL 36.266 36.934 37.706 4.0%
Source: AER99, T1.3*Includes coal coke net imports.
Factors Affecting ConsumptionBoth the U.S. population and per-capita energy use have beenincreasing, leading to growth in overall U.S. energyconsumption.
Although the U.S. Gross Domestic Product (GDP) increasedsteadily from 1997 to 1999, the amount of energy consumedper dollar of GDP dropped. Economic fluctuations particularlyimpact energy use in the industrial sector and also in thetransportation sector.
Weather conditions especially affect energy use in theresidential/commercial sector. For example, the number of“heating degree days” in winter or “cooling degree days” insummer affect the demand for space heating fuels or for theelectricity required for air-conditioning, respectively.
Table 4. Factors affecting U.S. energy consumption,1997–1999.
Change1997 1998 1999 1997–99
U.S. population(million) 267.8 270.2 272.7 1.8%
Energy consumptionper person (millionBtu) 352 350 354 0.6%
GDP (billionchained 1996dollars) 8,144.8 8,495.7 8,848.2 8.6%
Energy consumptionper $ of GDP (1000Btu per chained1996 dollar) 11.58 11.13 10.92 (5.7%)
Total heatingdegree days 4,542 3,951 4,244 —
Total coolingdegree days 1,156 1,410 1,228 —
Source: AER99, T1.5, 1.7, and 1.8. Chained 1996 dollars are a measure used toexpress real prices—i.e., prices adjusted to remove the effects of changes inthe purchasing power of the dollar—relative to 1996. Heating and coolingdegree days are relative measurements of outdoor air temperature. Thesedays indicate deviations of mean daily temperature: “heating degree days”are below 65°F and “cooling degree days” are above 65°F.
US En. Flow 98
3.8
0.01
0.03
5.2
Imports3.4
Imports
0.1
3.5
Nuclear 7.5
Export2.1
1.4Field use
0.8
0.1
0.8
0.6
<0.1
2.6
2.6
0.6
0.5
0.1
Export0.2
Storage0.6
7.8
1.111.6Hydro 3.4
Biomass+ other 3.4
Net electrical imports 0.3
U.S. Energy Flow – 1998Net Primary Resource Consumption 100 Exajoules
H. Miller
Prelim. 5/99
Stocks 0.5
Unacct'd 0.3
Natural gas20.5
4.64.3
21.0
Conversion and plant losses Rejectedenergy
54.9
23.9
4.64.3
21.0
Conversion and plant losses Rejectedenergy
54.9
23.9
Utilityconsumptionfor electricity
generation35.5
Unacct'd 0.10.2
Unacct’d crude0.5
17.2
Usefulenergy
36.2
13.8Coal24.9
5.44.1
2.2
25.4
Petroleumand NGL 16.5
Non–fuel6.2
Transpor-tation26.2
Distributed 12.5
ResidentialCommercial
18.4
Industrial21.6
Export2.1
1.2
Imports 23.4
8.28.3
Cogeneration 1.2
Other: geothermal, solar, wind, waste
Transmission losses
Stocks0.1
Strategic reserve0.1
19.8
US En. Flow 97
3.5
0.01
0.03
5.0
0.8
Imports3.0
Imports
3.0
3.5
0.1
Nuclear 6.7
Export2.2
Field use 1.3
0.7
0.1
0.7
0.6
0.2
2.4
2.4
0.90.6
2.40.1
Export0.2
Storage0.02
7.1
1.010.7Hydro 3.7
Biomass+ other 3.2
Net electrical imports 0.4
U.S. Energy Flow – 1997Net Primary Resource Consumption 94 Quads
H. Miller
Final 8/98
Stocks 0.3
Unacct'd 0.1
Natural gas19.5
4.64.2
19.9
Conversion and plant losses Rejectedenergy
51.8
22.1
4.64.2
19.9
Conversion and plant losses Rejectedenergy
51.8
22.1
Utilityconsumptionfor electricity
generation32.8
Unacct'd 0.040.2
16.9
Usefulenergy
35.8
13.9Coal23.2
18.4
5.43.9
2.2
24.0
Petroleumand NGL 16.1
Non–fuel
6.1
Transpor-tation24.9
Distributed 12.0
ResidentialCommercial
18.5
Industrial21.1
Export2.1
Imports 21.2
8.58.3
Cogeneration 1.4
Other: geothermal, solar, wind, waste
Transmission losses
Stocks0.3
Strategic reserve0.02
U.S. Energy Flow—1999, page 13
Credits and Web Locations
The production and end-use data in this chart were derived from:U.S. Department of Energy, Energy Information Administration, AnnualEnergy Review 1999, DOE/EIA-0384(99), Washington, D.C., July 2000.The report is available on the Web at http://www.eia.doe.gov/aer
The U.S. energy flow charts for 1998 and 1997 were prepared by HollyMiller of Lawrence Livermore National Laboratory. The 1998 chart givesenergy consumption in exajoules, the metric unit for heat. In 1998, theU.S. consumed 94.6 quads of energy, compared to 94.3 quads in 1997.
The energy flow charts prepared by Lawrence Livermore NationalLaboratory are available on the Web athttp://energy.llnl.gov/Analysis.html
Graphic artists: Lee Dravidzius and Helen Magann
University of CaliforniaLawrence Livermore National LaboratoryTechnical Information DepartmentLivermore, CA 94551
