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Chapter 15

Sources and Uses

We consume energy in dozens of forms. Yet virtually all of the energy we use originates in the power of the atom.

Nuclear reactions energize stars, including our sun. The energy we capture for use on Earth comes largely from

the sun or from nuclear forces local to our own planet.

Sunlight is by far the predominant source, and it contains a surprisingly large amount of energy. On average, even

after passing through hundreds of kilometers of air on a clear day, solar radiation reaches Earth with more than

enough energy in a single square meter to illuminate five 60-watt lightbulbs if all the sunlight could be captured

and converted to electricity.

The sun's energy warms the planet's surface, powering titanic transfers of heat and pressure in weather patterns

and ocean currents. The resulting air currents drive wind turbines. Solar energy also evaporates water that falls as

rain and builds up behind dams, where its motion is used to generate electricity via hydropower.

Most Americans, however, use solar energy in its secondhand form: fossil fuels. When sunlight strikes a plant,

some of the energy is trapped through photosynthesis and is stored in chemical bonds as the plant grows. We can

recover that energy months or years later by burning wood, which breaks the bonds and releases energy as heat

and light. More often, though, we use the stored energy in the much more concentrated forms that result when

organic matter, after millions of years of geological and chemical activity underground, turns into fossil fuels,

such as coal, oil, or natural gas. Either way, we're reclaiming the power of sunlight.

The only other original source of energy on Earth's surface is found in more local nuclear reactions, where atoms

of radioactive elements such as uranium split apart into smaller atoms and liberate energy in the process.

Harnessed as heat, the released energy boils water, producing steam that turns turbines, thereby being converted

to mechanical energy that generates electricity. Nuclear energy currently provides 20% of total electricity

generation in the United States.3

Finally, the heat of Earth's molten interior, itself largely the result of the nuclear decay of radioactive elements,

provides geothermal energy. At present, it is chiefly used in only a few places, such as California and Iceland,

where proximity to high temperature geothermal fields makes it practical.[*]

The High Cost of Change

By the time energy is delivered to us in a usable form, it has typically undergone several conversions. Every time

energy changes forms, some portion is lost. It doesn't disappear, of course. In nature, energy is always

conserved. That is, there is exactly as much of it around after something happens as there was before. But with

each change, some amount of the original energy turns into forms we don't want or can't use, typically as so-

called waste heat that is so diffuse it can't be captured.

Reducing the amount lost also known as increasing efficiency is as important to our energy future as finding

new sources because gigantic amounts of energy are lost every minute of every day in conversions. Electricity is a
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good example. By the time the energy content of electric power reaches the end user, it has taken many forms.

Most commonly, the process begins when coal is burned in a power station. The chemical energy stored in the

coal is liberated in combustion, generating heat that is used to produce steam. The steam turns a turbine, and

that mechanical energy is used to turn a generator to produce the electricity.

In the process, the original energy has taken on a series of four different identities and experienced four

conversion losses. A typical coal-fired electrical plant might be 38% efficient, so a little more than one-third of the

chemical energy content of the fuel is ultimately converted to usable electricity. In other words, as much as 62%

of the original energy fails to find its way to the electrical grid. Once electricity leaves the plant, further losses

occur during delivery. Finally, it reaches an incandescent lightbulb where it heats a thin wire filament until the

metal glows, wasting still more energy as heat. The resulting light contains only about 2% of the energy content of

the coal used to produce it. Swap that bulb for a compact fluorescent and the efficiency rises to around 5%

better, but still a small fraction of the original.4

Example of energy lost during conversion and transmission. Imaginethat the coal needed to illuminate an incandescent light bulb contains100 units of energy when it enters the power plant. Only two units of

that energy eventually light the bulb. The remaining 98 units are lost along the way,primarily as heat.

Another familiar form of conversion loss occurs in a vehicle's internal combustion engine. The chemical energy in

the gasoline is converted to heat energy, which provides pressure on the pistons. That mechanical energy is then

transferred to the wheels, increasing the vehicle's kinetic energy. Even with a host of modern improvements,

current vehicles use only about 20% of the energy content of the fuel as power, with the rest wasted as heat.

Electric motors typically have much higher efficiency ratings. But the rating only describes how much of the

electricity input they turn into power; it does not reflect how much of the original, primary energy is lost in

generating the electricity in the first place and then getting it to the motor.
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Efficiencies of heat engines can be improved further, but only to a degree. Principles of physics place upper limits

on how efficient they can be. Still, efforts are being made to capture more of the energy that is lost and to make

use of it. This already happens in vehicles in the winter months, when heat loss is captured and used to warm the

interior for passengers. In natural gas combined cycle, or NGCC, power plants, we now have technology that takes

the waste heat from a natural gas turbine and uses it to power a steam turbine, resulting in a power plant that is

as much as 60% efficient.5Similar technologies are being developed for use in coal power plants.

The energy sources that power our most indispensable devices often reflect convenience as much as efficiency.

Energy can take many forms, but modern society prefers those that are easily produced, distributed, and stored.

For example, American passenger cars are designed to hold enough onboard energy to travel 300 miles or so at a

reasonable rate of speed. That's easy to do with the relatively high chemical energy content of gasoline or diesel

fuel, despite the inefficiency of the engines.

If a car is powered by electricity, however, the energy has to be stored in batteries that have a much lower energy

density than gasoline does. To carry 300 miles' worth of energy, an electric car would need a lot of very heavy

batteries. Furthermore, it is difficult to deliver the energy needed to power an electric car in an acceptably short

time. Modern battery-powered cars charge at a rate roughly a thousand times slower than the rate of refueling

with gasoline, meaning overnight charging is required to store enough energy for a day's worth of driving. For

most Americans in the fast-paced 21st century, that's an unacceptably long time span.

Measuring Energy

Energy exists in many forms, so there are many ways to quantify it. Two of the most widely used for general

purposes are the British Thermal Unit (BTU), which is a measure of energy content, and the watt, which is a

measure of power, or how fast energy is used.One BTU is the amount of energy needed to raise a pound of water by one degree Fahrenheit. That's not a very

large amount. One cubic foot of natural gas contains around 1,000 BTUs. A gallon of gasoline is about 124,000

BTUs, and a ton of coal represents about 20 million BTUs. Enormous quantities, such as total U.S. energy

consumption in a year, are expressed in quads. One quad is a quadrillion that is, a million billion, or 1015

BTUs. America consumed about 100 quads in 2006.

One watt of power is equal to one ampere (a measure of electric current) moving at one volt (a measure of

electrical force). Again, this is a fairly small unit. U.S. household electricity is provided at 120 volts. So a 60-watt

lightbulb needs half an ampere of current to l ight up. For larger quantities, watts are usually expressed in

multiples of a thousand (kilowatt), million (megawatt), or billion (gigawatt). A big coal, natural gas, or nuclear

electrical plant can produce hundreds of megawatts; some of the largest generate one or more gigawatts. A

typical wind turbine has a one megawatt rating, and the largest are now four megawatts when turning. An

average U.S. household consumes electricity at the rate of a little more than one kilowatt, for an annual total of

about 10,000 kilowatt-hours (kilowatt-hours equal power multiplied by time).6

Energy and the Individual

Energy trade-offs and decisions permeate society, directly affecting everyday quality of life in many ways. Some

effects may be most noticeable at home or at least in household energy bills due to the rising costs of heating oil
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and natural gas. Residential energy use accounts for 21% of total U.S. consumption, and about one-third of that

goes into space heating, with the rest devoted, in decreasing proportions, to appliances, water heating, and air-

conditioning. So our personal preferences are intimately tied to, and immediately affect, the nation's overall

energy budget.

Percentage of energy consumed by each economic sector inthe United States in 2006.*7

* Percentages do not sum to 100% due to independent rounding.

Energy usage in the U.S. residential sector in 2006.8

Our individual automotive and public-transit choices also have a substantial impact, because transportation takes

up 28% of all U.S. energy consumption (and about 70% of all petroleum use). Even the 50% of total U.S. energy

consumption that goes to commercial and industrial uses affects every single citizen personally through the cost

of goods and services, the quality of manufactured products, the strength of the economy, and the availability of

jobs.
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The condition of the enviro

nment also holds consequences for all of us. Carbon dioxide (CO2) concentration in the atmosphere has risen

about 40% since the beginning of the industrial revolution from 270 parts per million (ppm) to 380 ppm and

contributes to global warming and ensuing climate change.9At present, the United States emits approximately

one-fourth of the world's greenhouse gases,10and the nation's CO2 emissions are projected to rise from about 5.9

billion metric tons in 2006 to 7.4 billion metric tons in 2030, assuming no changes to the control of carbon

emissions.11Of course this is not just a national concern. Worldwide, CO2 emissions are projected to increase

substantially, primarily as a result of increased development in China and India. Future decisions about whether

and how to limit greenhouse gas emissions will affect us all.

CO2 emissions by U.S. economic sector and energy source in 2005.12

Before we can consider ways to improve our energy situation we must first understand the resources we currently

depend on, as well as the pros and cons of using each one.

[*] One exception to the solar and local nuclear origins of Earth's energy promises only an exceedingly small contribution to our total

energy picture at present: Some engineers are exploring methods for capturing energy from ocean tides, thus tapping into a gravitational

source of energy.

Next:Supply and Demand

Introduction | Sources and Uses | Supply and Demand | ImprovingEfficiency | Emerging Technologies | Looking Ahead | References and Credits

2008 by the National Academy

Alternative energy is anumbrella termthat refers to any source of usableenergyintended to replace

fuel sources without the undesired consequences of the replaced fuels.[1]

The term "alternative" presupposes a set of undesirable energy technologies against which

"alternative energies" are contrasted. As such, the list of energy technologies excluded is an indicator

of which problems the alternative technologies are intended to address. Controversies regardingdominant sources of energy and their alternatives have a long history. The nature of what was
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regarded alternative energy sources has changed considerably over time, and today, because of the

variety of energy choices and differing goals of their advocates, defining some energy types as

"alternative" is highly controversial.

In a general sense in contemporary society, alternative energy is that which is produced without the

undesirable consequences of the burning offossil fuels, such as highcarbon dioxideemissions, whichis considered to be the major contributing factor ofglobal warmingaccording to theIntergovernmental

Panel on Climate Change. Sometimes, this less comprehensive meaning of "alternative energy"excludesnuclear energy(e.g. as defined in the Michigan Next Energy Authority Act of 2002).[2]

Contents

[hide]

1 Definitions

2 History

o 2.1 Coal as an alternative to wood

o 2.2 Petroleum as an alternative to whale oil

o 2.3 Alcohol as an alternative to fossil fuels

o 2.4 Coal gasification as an alternative to petroleum

3 Most common types of alternative energy

o 3.1 Solar energy

o 3.2 Wind energy

o 3.3 Geothermal energy

o 3.4 Biofuel and ethanol

o 3.5 Hydrogen

4 Renewable energy vs non-renewable energy

o 4.1 Ecologically friendly alternatives

5 Relatively new concepts for alternative energy

o 5.1 Algae fuel

o 5.2 Biomass briquettes

5.2.1 Biogas digestiono 5.3 Biological Hydrogen Production

o 5.4 Floating wind farms

6 Investing in alternative energy

o 6.1 Alternative energy in transportation

7 Making Alternative Energy Mainstream

8 Disadvantages

9 See also

10 References
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/Alternative_energy#Disadvantageshttp://en.wikipedia.org/wiki/Alternative_energy#Making_Alternative_Energy_Mainstreamhttp://en.wikipedia.org/wiki/Alternative_energy#Alternative_energy_in_transportationhttp://en.wikipedia.org/wiki/Alternative_energy#Investing_in_alternative_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Floating_wind_farmshttp://en.wikipedia.org/wiki/Alternative_energy#Biological_Hydrogen_Productionhttp://en.wikipedia.org/wiki/Alternative_energy#Biogas_digestionhttp://en.wikipedia.org/wiki/Alternative_energy#Biomass_briquetteshttp://en.wikipedia.org/wiki/Alternative_energy#Algae_fuelhttp://en.wikipedia.org/wiki/Alternative_energy#Relatively_new_concepts_for_alternative_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Ecologically_friendly_alternativeshttp://en.wikipedia.org/wiki/Alternative_energy#Renewable_energy_vs_non-renewable_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Hydrogenhttp://en.wikipedia.org/wiki/Alternative_energy#Biofuel_and_ethanolhttp://en.wikipedia.org/wiki/Alternative_energy#Geothermal_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Wind_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Solar_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Most_common_types_of_alternative_energyhttp://en.wikipedia.org/wiki/Alternative_energy#Coal_gasification_as_an_alternative_to_petroleumhttp://en.wikipedia.org/wiki/Alternative_energy#Alcohol_as_an_alternative_to_fossil_fuelshttp://en.wikipedia.org/wiki/Alternative_energy#Petroleum_as_an_alternative_to_whale_oilhttp://en.wikipedia.org/wiki/Alternative_energy#Coal_as_an_alternative_to_woodhttp://en.wikipedia.org/wiki/Alternative_energy#Historyhttp://en.wikipedia.org/wiki/Alternative_energy#Definitionshttp://en.wikipedia.org/wiki/Alternative_energyhttp://en.wikipedia.org/wiki/Alternative_energy#cite_note-1http://en.wikipedia.org/wiki/Nuclear_powerhttp://en.wikipedia.org/wiki/Intergovernmental_Panel_on_Climate_Changehttp://en.wikipedia.org/wiki/Intergovernmental_Panel_on_Climate_Changehttp://en.wikipedia.org/wiki/Global_warminghttp://en.wikipedia.org/wiki/Carbon_dioxidehttp://en.wikipedia.org/wiki/Fossil_fuel


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11 Further reading

[edit]Definitions

Source Definition

Oxford Dictionaryenergy fuelled in ways that do not use up natural resources or harm the

environment.[3]

Princeton WordNetenergy derived from sources that do not use up natural resources or harm

the environment.[4]

Responding to Climate

Change 2007

energy derived from nontraditional sources (e.g., compressed natural gas,

solar, hydroelectric, wind).[5]

Natural Resources

Defense Council

energy that is not popularly used and is usually environmentally sound, such

as solar or wind energy (as opposed to fossil fuels).[6]

Materials Management

Services

Fuel sources that are other than those derived from fossil fuels. Typically

used interchangeably forrenewable energy. Examples include: wind, solar,biomass, wave and tidal energy.[7]

TorridgeDistrict

CouncilEnergy generated from alternatives to fossil fuel. Need not be renewable.[8]

[edit]History

Historians of economies have studied the key transitions to alternative energies and regard thetransitions as pivotal in bringing about significant economic change.[9][10][11]Prior to shift to an

alternative energy, supplies of the dominant energy type became erratic, accompanied by rapid

increases in energy prices.

[edit]Coal as an alternative to wood

HistorianNorman F. Cantordescribes how in the late medieval period, coal was the new alternative

fuel to save the society from overuse of the dominant fuel, wood:

"Europeans had lived in the midst of vast forests throughout the earlier medieval centuries.

After 1250 they became so skilled at deforestation that by 1500 AD they were running short of

wood for heating and cooking... By 1500 Europe was on the edge of a fuel and nutritional
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disaster, [from] which it was saved in the sixteenth century only by the burning of soft coal

and the cultivation of potatoes and maize. "[12]

[edit]Petroleum as an alternative to whale oil

Whale oilwas the dominant form of lubrication and fuel for lamps in the early 19th century, but

thedepletion of the whale stocksby mid century caused whale oil prices to skyrocket setting thestage for the adoption of petroleum which was first commercialized inPennsylvaniain 1859.[13]

[edit]Alcohol as an alternative to fossil fuels

Main article:Ethanol fuel

In 1917,Alexander Graham Belladvocatedethanolfrom corn, wheat and other foodstuffs as an

alternative to coal and oil, stating that the world was in measurable distance of depleting these

fuels. For Bell, the problem requiring an alternative was lack of renewability of orthodox energy

sources.[14]Since the 1970s,Brazil has had an ethanol fuel programwhich has allowed the

country to become the world's second largest producer ofethanol(after the United States) and

the world's largest exporter.[15]Brazils ethanol fuel program uses modern equipment andcheapsugar caneas feedstock, and the residual cane-waste (bagasse) is used to process heat

and power.[16]There are no longer light vehicles in Brazil running on pure gasoline. By the end of2008 there were 35,000 filling stations throughout Brazil with at least one ethanol pump.[17]

Cellulosic ethanolcan be produced from a diverse array of feedstocks, and involves the use of

the whole crop. This new approach should increase yields and reduce thecarbon

footprintbecause the amount of energy-intensive fertilizers and fungicides will remain the same,

for a higher output of usable material.[18][19]As of 2008, there are ninecommercial cellulosic

ethanol plantswhich are either operating, or under construction, in the United States.[20]

Second-generation biofuelstechnologies are able to manufacture biofuels from inedible biomassand could hence prevent conversion of food into fuel."[21]As of July 2010, there is onecommercial second-generation (2G) ethanol plantInbicon Biomass Refinery, which is operating in

Denmark.[22]

[edit]Coal gasification as an alternative to petroleum

In the 1970s, PresidentJimmy Carter's administration advocatedcoal gasificationas analternative to expensive imported oil. The program, including theSynthetic Fuels Corporationwas

scrapped when petroleum prices plummeted in the 1980s. The carbon footprint and

environmental impact ofcoal gasificationare both very high.

[edit]Most common types of alternative energy

[edit]Solar energy

Solar energyis generating of electricity from the sun. It is split up into two types, thermal and

electric energy.

[edit]Wind energy

Wind energyis generating of electricity from the wind

[edit]Geothermal energy

Geothermal energyis using hot water or steam from the Earths interior for heating buildings or

electricity generation.[edit]Biofuel and ethanol
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ikipedia.org/wiki/Coal_gasificationhttp://en.wikipedia.org/wiki/Synthetic_Fuels_Corporationhttp://en.wikipedia.org/wiki/Synthetic_Fuels_Corporationhttp://en.wikipedia.org/wiki/Synthetic_Fuels_Corporationhttp://en.wikipedia.org/wiki/Coal_gasificationhttp://en.wikipedia.org/wiki/Coal_gasificationhttp://en.wikipedia.org/wiki/Coal_gasificationhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=7http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=7http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=7http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=8http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=8http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=8http://en.wikipedia.org/wiki/Solar_energyhttp://en.wikipedia.org/wiki/Solar_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=9http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=9http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=9http://en.wikipedia.org/wiki/Wind_energyhttp://en.wikipedia.org/wiki/Wind_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=10http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=10http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=10http://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=11http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=11http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=11http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=11http://en.wikipedia.org/wiki/Geothermal_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=10http://en.wikipedia.org/wiki/Wind_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=9http://en.wikipedia.org/wiki/Solar_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=8http://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=7http://en.wikipedia.org/wiki/Coal_gasificationhttp://en.wikipedia.org/wiki/Synthetic_Fuels_Corporationhttp://en.wikipedia.org/wiki/Coal_gasificationhttp://en.wikipedia.org/wiki/Jimmy_Carterhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=6http://en.wikipedia.org/wiki/Alternative_energy#cite_note-21http://en.wikipedia.org/w/index.php?title=Inbicon&action=edit&redlink=1http://en.wikipedia.org/wiki/Alternative_energy#cite_note-20http://en.wikipedia.org/w/index.php?title=Second-generation_biofuels&action=edit&redlink=1http://en.wikipedia.org/wiki/Alternative_energy#cite_note-19http://en.wikipedia.org/wiki/Cellulosic_ethanol_commercializationhttp://en.wikipedia.org/wiki/Cellulosic_ethanol_commercializationhttp://en.wikipedia.org/wiki/Alternative_energy#cite_note-17http://en.wikipedia.org/wiki/Alternative_energy#cite_note-17http://en.wikipedia.org/wiki/Carbon_footprinthttp://en.wikipedia.org/wiki/Carbon_footprinthttp://en.wikipedia.org/wiki/Cellulosic_ethanolhttp://en.wikipedia.org/wiki/Alternative_energy#cite_note-Wilson-16http://en.wikipedia.org/wiki/Alternative_energy#cite_note-MLA_2004-15http://en.wikipedia.org/wiki/Bagassehttp://en.wikipedia.org/wiki/Sugar_canehttp://en.wikipedia.org/wiki/Alternative_energy#cite_note-RFA1E-14http://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Ethanol_fuel_in_Brazilhttp://en.wikipedia.org/wiki/Alternative_energy#cite_note-13http://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Alexander_Graham_Bellhttp://en.wikipedia.org/wiki/Ethanol_fuelhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=5http://en.wikipedia.org/wiki/Alternative_energy#cite_note-12http://en.wikipedia.org/wiki/Titusville,_Pennsylvaniahttp://en.wikipedia.org/wiki/History_of_whalinghttp://en.wikipedia.org/wiki/Whale_oilhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=4http://en.wikipedia.org/wiki/Alternative_energy#cite_note-11


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Biofuelandethanolare plant-derived substitutes of gasoline for powering vehicles.

[edit]Hydrogen

Hydrogenis used as clean fuel for airplanes, spaceships, and vehicles.

Hydrogen alternative energy and nuclear energy are also frequently mentioned as the alternative

sources of energy; however, they are surrounded by growing disputes on their safety for theenvironment, so it is still unclear how long those energy sources will remain marked as alternative

and environment friendly energy sources.[23]

[edit]Renewable energy vs non-renewable energy

Main article:Renewable energy

Renewable energy is generated fromnatural resourcessuch

assunlight,[24]wind,rain,tidesandgeothermal heatwhich are renewable (naturally

replenished). When comparing the processes for producing energy, there remain severalfundamental differences between renewable energy and fossil fuels. The process of producing

oil, coal, or natural gas fuel is a difficult and demanding process that requires a great deal of

complex equipment, physical and chemical processes. On the other hand, alternative energy can

be widely produced with basic equipment and naturally basic processes. Wood, the mostrenewable and available alternative energy, burns the same amount of carbon it would emit if it

degraded naturally.[25]

[edit]Ecologically friendly alternatives

Renewable energy sources such asbiomassare sometimes regarded as an alternative to

ecologically harmful fossil fuels. Renewables are not inherently alternative energies for this

purpose. For example, theNetherlands, once leader in use ofpalm oilas a biofuel, has

suspended all subsidies for palm oil due to the scientific evidence that their use "may sometimescreate more environmental harm than fossil fuels".[26]The Netherlands government and

environmental groups are trying to trace the origins of imported palm oil, to certify which

operations produce the oil in a responsible manner.[26]Regarding biofuels from foodstuffs, the

realization that converting the entire grain harvest of the US would only produce 16% of its autofuel needs, and the decimation of Brazil's CO2 absorbing tropical rain forests to make way for

biofuel production has made it clear that placing energy markets in competition with food markets

results in higher food prices and insignificant or negative impact on energy issues such as global

warming or dependence on foreign energy.[27]Recently, alternatives to such undesirablesustainable fuels are being sought, such as commercially viable sources of cellulosic ethanol.

[edit]Relatively new concepts for alternative energy[edit]Algae fuel

Algae fuelis abiofuelwhich is derived from algae. During photosynthesis, algae and other

photosynthetic organisms capture carbon dioxide and sunlight and convert it into oxygen and

biomass. The benefits of algal biofuel are that it can be produced industrially, thereby obviating

the use of arable land and food crops (such as soy, palm, and canola), and that it has a very high

oil yield as compared to all other sources of biofuel.

[edit]Biomass briquettes

Biomass briquettesare being developed in the developing world as an alternative to charcoal.

The technique involves the conversion of almost any plant matter into compressed briquettes that
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dia.org/wiki/Tidal_energyhttp://en.wikipedia.org/wiki/Rainhttp://en.wikipedia.org/wiki/Windhttp://en.wikipedia.org/wiki/Alternative_energy#cite_note-23http://en.wikipedia.org/wiki/Sunlighthttp://en.wikipedia.org/wiki/Natural_resourcehttp://en.wikipedia.org/wiki/Renewable_energyhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=13http://en.wikipedia.org/wiki/Alternative_energy#cite_note-22http://en.wikipedia.org/wiki/Hydrogenhttp://en.wikipedia.org/w/index.php?title=Alternative_energy&action=edit&section=12http://en.wikipedia.org/wiki/Ethanolhttp://en.wikipedia.org/wiki/Biofuel


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typically have about 70% the calorific value of charcoal. There are relatively few examples of

large scale briquette production. One exception is in North Kivu, in easternDemocratic Republic

of Congo, where forest clearance for charcoal production is considered to be the biggest threat to

Mountain Gorilla habitat. The staff ofVirunga National Parkhave successfully trained and

equipped over 3500 people to produce biomass briquettes, thereby replacing charcoal produced

illegally inside the national park, and creating significant employment for people living in extremepoverty in conflict affected areas.[28]

[edit]Biogas digestion

Biogasdigestion deals with harnessing the methane gas that is released when waste breaks

down. This gas can be retrieved from garbage or sewage systems. Biogas digesters are used to

process methane gas by having bacteria break downbiomassin an anaerobicenvironment.[29]The methane gas that is collected and refined can be used as an energy source

for various products.

[edit]Biological Hydrogen Production

Hydrogen gas is a completely clean burning fuel; its only by-product is water.[30]It also containsrelatively high amount of energy compared with other fuels due to its chemical structure.[31]

2H2 + O2 2H2O + High Energy

High Energy + 2H2O 2H2 + O2

This requires a high-energy input, making commercial hydrogen very inefficient.[32]Use of a

biological vector as a means to split water, and therefore produce hydrogen gas, would allow for

the only energy input to be solar radiation. Biological vectors can include bacteria or more

commonly algae. This process is known asbiological hydrogen production.[33]It requires the useof single celled organisms to create hydrogen gas through fermentation. Without the presence of

oxygen, also known as an anaerobic environment, regular cellular respiration cannot take placeand a process known as fermentation takes over. A major by-product of this process is hydrogen

gas. If we could implement this on a large scale, then we could take sunlight, nutrients and waterand create hydrogen gas to be used as a dense source of energy.[34]Large-scale production has

proven difficult. It was not until 1999 that we were able to even induce these anaerobic conditions

by sulfur deprivation.[35]Since the fermentation process is an evolutionary back up, turned on

during stress, the cells would die after a few days. In 2000, a two-stage process was developedto take the cells in and out of anaerobic conditions and therefore keep them alive.[36]For the last

ten years, finding a way to do this on a large-scale has been the main goal of research. Careful

work is being done to ensure an efficient process before large-scale production, however once a

mechanism is developed, this type of production could solve our energy needs.[37]

[edit]Floating wind farms

Floatingwind farmsare similar to a regular wind farm, but the difference is that they float in the

middle of the ocean. Offshore wind farms can be placed in water up to 40 metres (130 ft) deep,

whereas floating wind turbines can float in water up to 700 metres (2,300 ft) deep.[38]The

advantage of having a floating wind farm is to be able to harness the winds from the open ocean.

Without any obstructions such as hills, trees and buildings, winds from the open ocean can reach

up to speeds twice as fast as coastal areas.[39]

[edit]Investing in alternative energy

Over the last three years publicly traded alternative energy have been very volatile, with some

2007 returns in excess of 100%, some 2008 returns down 90% or more, and peak-to-trough
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returns in 2009 again over 100%.[citation needed] In general there are three subsegments of

alternative energy investment: solar energy, wind energy and hybrid electric vehicles.

Alternative energy sources which are renewable, free and have lower carbon emissions than

what we have now are wind energy, solar energy, geothermal energy, and bio fuels. Each of

these four segments involve very different technologies and investment concerns.

For example, photovoltaic solar energy is based on semiconductor processing and accordingly,

benefits from steep cost reductions similar to those realized in the microprocessor industry (i.e.,driven by larger scale, higher module efficiency, and improving processing technologies). PV

solar energy is perhaps the only energy technology whose electricity generation cost could be

reduced by half or more over the next 5 years. Better and more efficient manufacturing process

and new technology such as advanced thin film solar cell is a good example of that helps to

reduce industry cost.[40]

The economics of solar PV electricity are highly dependent on silicon pricing and even companies

whose technologies are based on other materials (e.g., First Solar) are impacted by the balance

of supply and demand in the silicon market.

[citation needed]

In addition, because some companies sellcompleted solar cells on the open market (e.g., Q-Cells), this creates a low barrier to entry for

companies that want to manufacture solar modules, which in turn can create an irrational pricing

environment.

In contrast, because wind power has been harnessed for over 100 years, its underlyingtechnology is relatively stable. Its economics are largely determined by siting (e.g., how hard the

wind blows and the grid investment requirements) and the prices of steel (the largest component

of a wind turbine) and select composites (used for the blades). Because current wind turbines are

often in excess of 100 meters high, logistics and a global manufacturing platform are majorsources of competitive advantage. These issues and others were explored in a research report by

Sanford Bernstein. Some of its key conclusions are shown here.

[26]

[edit]Alternative energy in transportation

Due to steadily rising gas prices in 2008 with the US national average price per gallon of regular

unleaded gas rising above $4.00 at one point,[41]there has been a steady movement towards

developing higher fuel efficiency and morealternative fuelvehicles for consumers. In response,

many smaller companies have rapidly increased research and development into radically differentways of powering consumer vehicles.Hybridandbattery electric vehiclesare commercially

available and are gaining wider industry and consumer acceptance worldwide.[42]

For example, Nissan USA introduced the world's first mass-production Electric Vehicle "Nissan

Leaf".[43]

[edit]Making Alternative Energy Mainstream

Before alternative energy becomes main-stream there are a few crucial obstacles that it must

overcome: First there must be increased understanding of how alternative energies work and why

they are beneficial; secondly the availability components for these systems must increase; and

lastly the pay-off time must be decreased.

For example,electric vehicles(EV) andPlug-in Hybrid Electric Vehicles(PHEV) are on the rise.

These vehicles depend heavily on an effective charging infrastructure such as asmart

gridinfrastructure to be able to implement electricity as mainstream alternative energy for future

transportations.

[44][unreliable source?]
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[edit]Disadvantages

There are a number of issues that would arise from switching to alternative energy. Increasing

the nations use of natural gas for electricity generation could result in adverse economic

consequences, especiallysince natural gas currently costs about four times more than

coal.[45]Furthermore, if there were a widespread switching to natural gas from coal the UnitedStates would become increasingly dependent on international supplies. Also, large-scale fuel

switching would require substantial investments in pipeline storage and storage capacity and newterminals to process imported natural gas.[45]There is also the question of whether to convert

existing coal-burning plants or to construct new ones. Burning natural gas at an existing coal

plant would require a pipeline with the ability to meet the plants fuel supply requirements.[45]It

would also require expansion of interstate and intrastate pipelines to transport increasedvolumes of natural gas[45]Overall it would be more feasible and cost-effective to construct new

natural gas units than to switch coal-burning plants.

EcologyFrom Wikipedia, the free encyclopedia

For other uses, seeEcology (disambiguation).

Ecology
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The scientific discipline of ecology addresses the full scale of life, from

tiny bacteria to processes that span the entire planet. Ecologists study

many diverse andcomplex relationsamong species, such

aspredationandpollination. The diversity of life is organized into

differenthabitats, fromterrestrial(middle) toaquatic ecosystems.

Ecology (fromGreek:, "house"; -, "study of") is thescientificstudy of the relations that

livingorganismshave with respect to each other and theirnatural environment.Variablesof interest to

ecologists include the composition, distribution, amount (biomass), number, and changing states of

organisms within and amongecosystems. Ecosystems are hierarchical systems that are organized into a

graded series of regularly interacting and semi-independent parts (e.g.,species) that aggregate into higher

orders ofcomplexintegrated wholes (e.g.,communities). Ecosystems are sustained by

thebiodiversitywithin them. Biodiversity is the full-scale of life and its processes, including genes, species

and ecosystems forming lineages that integrate into a complex andregenerativespatial arrangementoftypes, forms, and interactions. Ecosystems createbiophysicalfeedback mechanisms between living (biotic)

and nonliving (abiotic) components of the planet. These feedback loops regulate and sustain local

communities,continental climatesystems, and globalbiogeochemical cycles.

Ecology is a sub-discipline ofbiology, the study oflife. The word "ecology" ("kologie") was coined in 1866

by the German scientistErnst Haeckel(18341919). Ancient philosophers of Greece,

includingHippocratesandAristotle, were among the earliest to record notes and observations on

thenatural historyof plants and animals. Modern ecology branched out of natural history and matured into

a more rigoroussciencein the late 19th century. Charles Darwin'sevolutionarytreatise including theconcept of adaptation, as it was introduced in 1859, is a pivotal cornerstone in modernecological theory.

Ecology is not synonymous with environment,environmentalism,natural historyorenvironmental science.

It is closely related tophysiology, evolutionary biology,geneticsandethology. An understanding of how

biodiversity affects ecological function is an important focus area in ecological studies. Ecologists seek to

explain:

Life processes andadaptations

Distribution and abundance oforganisms

The movement of materials andenergythrough living communities
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a.org/wiki/Adaptationshttp://en.wikipedia.org/wiki/Adaptationshttp://en.wikipedia.org/wiki/Adaptationshttp://en.wikipedia.org/wiki/Organismshttp://en.wikipedia.org/wiki/Organismshttp://en.wikipedia.org/wiki/Organismshttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/File:Blue_Linckia_Starfish.JPGhttp://en.wikipedia.org/wiki/File:Bufo_boreas.jpghttp://en.wikipedia.org/wiki/File:Blue_Linckia_Starfish.JPGhttp://en.wikipedia.org/wiki/File:Bufo_boreas.jpghttp://en.wikipedia.org/wiki/Energyhttp://en.wikipedia.org/wiki/Organismshttp://en.wikipedia.org/wiki/Adaptationshttp://en.wikipedia.org/wiki/Ethologyhttp://en.wikipedia.org/wiki/Geneticshttp://en.wikipedia.org/wiki/Physiologyhttp://en.wikipedia.org/wiki/Environmental_sciencehttp://en.wikipedia.org/wiki/Natural_historyhttp://en.wikipedia.org/wiki/Environmentalismhttp://en.wikipedia.org/wiki/Ecological_theoryhttp://en.wikipedia.org/wiki/Evolutionhttp://en.wikipedia.org/wiki/Natural_scienceshttp://en.wikipedia.org/wiki/Natural_historyhttp://en.wikipedia.org/wiki/Aristotlehttp://en.wikipedia.org/wiki/Hippocrateshttp://en.wikipedia.org/wiki/Ernst_Haeckelhttp://en.wikipedia.org/wiki/Lifehttp://en.wikipedia.org/wiki/Biologyhttp://en.wikipedia.org/wiki/Biogeochemical_cycleshttp://en.wikipedia.org/wiki/Continental_climatehttp://en.wikipedia.org/wiki/Abiotichttp://en.wikipedia.org/wiki/Biotic_componenthttp://en.wikipedia.org/wiki/Biophysicshttp://en.wikipedia.org/wiki/Spatial_ecologyhttp://en.wikipedia.org/wiki/Regeneration_(biology)http://en.wikipedia.org/wiki/Biodiversityhttp://en.wikipedia.org/wiki/Community_(ecology)http://en.wikipedia.org/wiki/Complexityhttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Ecosystemshttp://en.wikipedia.org/wiki/Biomasshttp://en.wikipedia.org/wiki/Variable_and_attribute_(research)http://en.wikipedia.org/wiki/Natural_environmenthttp://en.wikipedia.org/wiki/Organismhttp://en.wikipedia.org/wiki/Sciencehttp://en.wikipedia.org/wiki/Greek_languagehttp://en.wikipedia.org/wiki/Aquatic_ecosystemhttp://en.wikipedia.org/wiki/Terrestrial_ecosystemhttp://en.wikipedia.org/wiki/Habitatshttp://en.wikipedia.org/wiki/Pollinationhttp://en.wikipedia.org/wiki/Predationhttp://en.wikipedia.org/wiki/Interspecific_interactions


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Thesuccessionaldevelopment of ecosystems, and

Theabundanceand distribution ofbiodiversityin context of theenvironment.

Ecology is a human science as well. There are many practical applications of ecology in conservation

biology, wetland management,natural resource management(agriculture,forestry,fisheries), city planning(urban ecology),community health,economics,basicandapplied scienceand human social interaction

(human ecology). Ecosystems sustain every life-supporting function on the planet,

includingclimateregulation, water filtration,soilformation (pedogenesis), food, fibers, medicines, erosion

control, and many other natural features of scientific, historical or spiritual value .[1][2][3]

Contents

1 Integrative levels, scope, and scale of organization

o 1.1 Hierarchical ecology

o 1.2 Biodiversity

o 1.3 Habitat

o 1.4 Niche

1.4.1 Niche construction

o 1.5 Biome

o 1.6 Biosphere

o 1.7 Population ecology

1.7.1 Metapopulations and migration

o 1.8 Community ecology

o 1.9 Ecosystem ecology

1.9.1 Food webs

1.9.2 Trophic levels

1.9.3 Keystone species

o 1.10 Soils

2 Ecological complexity

o 2.1 Holism

3 Relation to evolution

o 3.1 Behavioral ecology

o 3.2 Social ecology

o 3.3 Coevolution

o 3.4 Biogeography

3.4.1 r/K-Selection theory

o 3.5 Molecular ecology

4 Human ecology
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