Sustainable energy
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'''Sustainable energy''' is the provision of energy such that it meets the needs of the present without compromising the ability of future generations to meet their needs. A broader interpretation may allow inclusion of [[fossil fuel]]s and [[nuclear fission]] as transitional sources while technology develops, as long as new sources are developed for future generations to use. A narrower interpretation includes only energy sources which are not expected to be depleted in a timeframe relevant to the human race.
Sustainable energy sources are most often regarded as including all [[renewable energy|renewable]] sources, such as [[biofuels]], [[solar power]], [[wind power]], [[wave power]], [[geothermal power]] and [[tidal power]]. It usually also includes technologies that improve [[energy efficiency]]. Conventional [[nuclear power]] and [[fusion power]] may be included, but they are controversial politically due to concerns about waste disposal and the risks of disaster due to accident, terrorism, or natural disaster.
==Distinction from other terms==
Some ways in which ''sustainable energy'' has been defined are:
*"Effectively, the provision of energy such that it meets the needs of the future without compromising the ability of future generations to meet their own needs. ...Sustainable Energy has two key components: renewable energy and energy efficiency." – ''Renewable Energy and Efficiency Partnership'' (British)<ref>{{cite web |url=http://www.reeep.org/file_upload/296_tmpphpXkSxyj.pdf |title=Glossary of terms in sustainable energy regulation |author=Renewable Energy and Efficiency Partnership |month=August |year=2004 |accessdate=2008-04-19 |format=pdf}} </ref>
*"Energy which is replenishable within a human lifetime and causes no long-term damage to the environment." – ''Jamaica Sustainable Development Network''<ref>{{cite web |url=http://www.jsdnp.org.jm/glossary.html |title=Glossary of terms |author=Jamaica Sustainable Development Network |accessdate=2008-04-19}}</ref>
This sets ''sustainable energy'' apart from other [[renewable energy]] terminology such as ''[[alternative energy]]'' and ''[[green energy]]'', by focusing on the ability of an energy source to continue providing energy. Sustainable energy can produce some pollution of the environment, as long as it is not sufficient to prohibit heavy use of the source for an indefinite amount of time.
==Renewable energy technologies==
{{Renewable energy sources}}
{{Main|Renewable energy commercialization}}
[[Renewable energy]] technologies are essential contributors to sustainable energy as they generally contribute to world [[energy security]], reducing dependence on [[fossil fuel]] resources, and providing opportunities for mitigating [[greenhouse gases]].<ref name="IEA">International Energy Agency (2007).
[http://www.iea.org/textbase/papers/2006/renewable_factsheet.pdf ''Renewables in global energy supply: An IEA facts sheet''], OECD, 34 pages.</ref> The [[International Energy Agency]] has defined three generations of renewable energy technologies, reaching back more than 100 years:<ref name="IEA"/>
*''First-generation technologies'' emerged from the [[industrial revolution]] at the end of the 19th century and include [[hydropower]], [[biomass]] combustion, and [[geothermal power]] and heat. Some of these technologies are still in widespread use.
*''Second-generation technologies'' include [[solar heating]] and cooling, [[wind power]], modern forms of [[bioenergy]], and [[solar photovoltaics]]. These are now entering markets as a result of research, development and demonstration (RD&D) investments since the 1980s. The initial investment was prompted by [[energy security]] concerns linked to the [[oil crises]] of the 1970s but the continuing appeal of these renewables is due, at least in part, to environmental benefits. Many of the technologies reflect significant advancements in materials.
*''Third-generation technologies'' are still under development and include advanced [[biomass gasification]], [[biorefinery]] technologies, concentrating [[solar thermal]] power, [[hot dry rock geothermal energy]], and [[ocean energy]]. Advances in [[nanotechnology]] may also play a major role.<ref name="IEA"/>
First- and second-generation technologies have entered the markets, and third-generation technologies heavily depend on long term research and development commitments, where the public sector has a role to play.<ref name="IEA"/>
===First-generation technologies===
[[Image:Hydroelectric dam.png|thumb|right|230px|Hydroelectric dam in cross section]]
[[Image:West Ford Flat Geothermal Cooling Tower.JPG|thumb|right|250px|West Ford Flat Geothermal Cooling Tower.JPG|thumb|right|230px|One of many power plants at [[The Geysers]], a geothermal power field in northern California, with a total output of over 750 MW.]]
First-generation technologies are most competitive in locations with abundant resources. Their future use depends on the exploration of the available resource potential, particularly in developing countries, and on overcoming challenges related to the environment and social acceptance. Among sources of renewable energy, hydroelectric plants have the advantages of being long-lived -- many existing plants have operated for more than 100 years. Also, hydroelectric plants are clean and have few emissions. Criticisms directed at large-scale hydroelectric plants include: dislocation of people living where the reservoirs are planned, and release of significant amounts of carbon dioxide during construction and flooding of the reservoir.<ref>[http://www.newscientist.com/article.ns?id=dn7046 Hydroelectric power's dirty secret revealed] ''New Scientist'', 24 February 2005.</ref> However, it has been found that high emissions are associated only with shallow reservoirs in warm (tropical) locales. Generally speaking, hydroelectric plants produce much lower life-cycle emissions than other types of generation. Hydroelectric power, which underwent extensive development during growth of electrification in the 19th and 20th centuries, is experiencing resurgence of development in the 21st century. The areas of greatest hydroelectric growth are the booming economies of Asia. China is the development leader; however, other Asian nations are installing hydropower at a rapid pace. This growth is driven by much increased energy costs -- especially for imported energy -- and widespread desires for more domestically-produced, clean, renewable, and economical generation.
[[Geothermal power]] plants can operate 24 hours per day, providing base-load capacity, and the world potential capacity for geothermal power generation is estimated at 85 GW over the next 30 years. However, geothermal power is accessible only in limited areas of the world, including the United States, Central America, Indonesia, East Africa and the Philippines. The costs of geothermal energy have dropped substantially from the systems built in the 1970s.<ref name="IEA" /> [[Geothermal heat]] generation can be competitive in many countries producing geothermal power, or in other regions where the resource is of a lower temperature.
===Second-generation technologies===
Markets for second-generation technologies are strong and growing, mainly in countries such as Germany, Spain, the United States, and Japan. The challenge is to broaden the market base for continued growth worldwide. Strategic deployment in one country not only reduces technology costs for users there, but also for those in other countries, contributing to overall cost reductions and performance improvement.<ref name="IEA"/>
[[Solar heating]] systems are a well known second-generation technology and generally consist of solar thermal collectors, a fluid system to move the heat from the collector to its point of usage, and a reservoir or tank for heat storage and subsequent use. The systems may be used to heat domestic hot water, swimming pool water, or for space heating.<ref>[http://www.rmi.org/sitepages/pid705.php Solar water heating]</ref> The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment.<ref>[http://www.iea-shc.org/task25/index.html Solar assisted air-conditioning of buildings]</ref> In many climates, a solar heating system can provide a very high percentage (50 to 75%) of domestic hot water energy.
[[Image:SolarPowerPlantSerpa.jpg|300px|right|thumb|11 MW solar power plant near Serpa, Portugal {{coor dms|38|1|51|N|7|37|22|W|}}]]
In the 1980s and early 1990s, most photovoltaic modules provided [[Remote Area Power Supply]], but from around 1995, industry efforts have focused increasingly on developing [[building integrated photovoltaics]] and power plants for grid connected applications (see [[photovoltaic power stations]] article for details). Currently the largest photovoltaic power plant in North America is the [[Nellis Solar Power Plant]] (15 MW).<ref name=prn1>[http://www.prnewswire.com/cgi-bin/stories.pl?ACCT=ind_focus.story&STORY=/www/story/04-23-2007/0004571089&EDATE=MON+Apr+23+2007,+08:00+AM Largest U.S. Solar Photovoltaic System Begins Construction at Nellis Air Force Base]</ref><ref>[http://www.nellis.af.mil/news/story.asp?id=123079933 Nellis activates Nations largest PV Array]</ref> There is a proposal to build a [[Solar power station in Victoria]], Australia, which would be the world's largest PV power station, at 154 MW.<ref>[http://technology.timesonline.co.uk/tol/news/tech_and_web/article613720.ece Australia advances with solar power] ''The Times'', 26 October 2006.</ref> <ref>[http://www.solarsystems.com.au/projects.html Solar Systems projects]</ref> Other large photovoltaic power stations, which have been proposed or are under construction, include the [[Girassol solar power plant]] (62 MW),<ref>[http://www.renewableenergyaccess.com/rea/news/story?id=39442 62 MW Solar PV Project Quietly Moves Forward] ''Renewable Energy Access'', 18 November 2005.</ref> and the [[Waldpolenz Solar Park]] (40 MW).<ref>[http://www.juwi.de/international/information/press/PR_Solar_Power_Plant_Brandis_2007_02_eng.pdf World’s largest solar power plant being built in eastern Germany]</ref>
[[Image:Wind 2006andprediction en.png|thumb|400px|Worldwide installed capacity and prediction 1997-2010, Source: [http://www.wwindea.org/ WWEA]]]
[[Image:EthanolPetrol.jpg|right||250px|thumb|Information on pump, California.]]
Some of the second-generation renewables, such as wind power, have high potential and have already realised relatively low production costs. At the end of 2006, worldwide capacity of wind-powered generators was 74,223 [[megawatt]]s, and although it currently produces less than 1% of world-wide electricity use, it accounts for approximately 20% of electricity use in [[Wind power in Denmark|Denmark]], 9% in [[Wind power in Spain|Spain]], and 7% in [[Wind power in Germany|Germany]].<ref>[http://www.gwec.net/uploads/media/07-02_PR_Global_Statistics_2006.pdf Global wind energy markets continue to boom – 2006 another record year]</ref><ref>[http://www.ibtimes.com/articles/20070425/european-wind-companies-grow-in-u-s.htm European wind companies grow in U.S.]</ref> However, it may be difficult to site wind turbines in some areas for aesthetic or environmental reasons, and it may be difficult to integrate wind power into electricity grids in some cases.<ref name="IEA"/>
[[Brazil]] has one of the largest renewable energy programs in the world, involving production of [[ethanol fuel]] from [[sugar cane]], and [[ethanol]] now provides 18 percent of the country's automotive fuel. As a result of this, together with the exploitation of domestic deep water oil sources, Brazil, which years ago had to import a large share of the petroleum needed for domestic consumption, recently reached complete self-sufficiency in oil.<ref>[http://www.renewableenergyaccess.com/rea/news/story?id=44896 America and Brazil Intersect on Ethanol] ''Renewable Energy Access'', 15 May 2006. </ref><ref>[http://cesp.stanford.edu/news/oil_addiction_20060417/ How to manage our oil addiction - CESP]</ref><ref>[http://www.washingtonpost.com/wp-dyn/content/article/2006/04/21/AR2006042100139.html New Rig Brings Brazil Oil Self-Sufficiency] ''Washington Post'', 21 April 2006.</ref>
Most cars on the road today in the U.S. can run on blends of up to 10% ethanol, and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. [[Ford Motor Company|Ford]], [[DaimlerChrysler]], and [[General Motors Corporation|GM]] are among the automobile companies that sell “flexible-fuel” cars, trucks, and minivans that can use gasoline and ethanol blends ranging from pure gasoline up to 85% ethanol (E85). By mid-2006, there were approximately six million E85-compatible vehicles on U.S. roads.<ref name="world">Worldwatch Institute and Center for American Progress (2006). [http://images1.americanprogress.org/il80web20037/americanenergynow/AmericanEnergy.pdf ''American energy: The renewable path to energy security'']</ref>
===Third-generation technologies===
Third-generation technologies are still under development and include advanced [[biomass gasification]], [[biorefinery]] technologies, [[solar thermal]] power stations, [[hot dry rock geothermal energy]], and [[ocean energy]].<ref name="IEA" /> Third-generation technologies are not yet widely demonstrated or have limited commercialization. Many are on the horizon and may have potential comparable to other renewable energy technologies, but still depend on attracting sufficient attention and RD&D funding.<ref name="IEA" />
According to the International Energy Agency, new bioenergy (biofuel) technologies being developed today, notably cellulosic ethanol biorefineries, could allow biofuels to play a much bigger role in the future than previously thought.<ref>International Energy Agency (2006). [http://www.worldenergyoutlook.org/summaries2006/English.pdf ''World Energy Outlook 2006''] p. 8.</ref> Cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants. Crop residues (such as corn stalks, wheat straw and rice straw), wood waste, and municipal solid waste are potential sources of cellulosic biomass. Dedicated energy crops, such as switchgrass, are also promising cellulose sources that can be sustainably produced in many regions of the United States.<ref>Biotechnology Industry Organization (2007). [http://bio.org/ind/biofuel/CellulosicEthanolIssueBrief.pdf ''Industrial Biotechnology Is Revolutionizing the Production of Ethanol Transportation Fuel''] pp. 3-4.</ref>
[[Image:Smallsketch.jpg|250px|thumb|right|Sketch of a Parabolic Trough Collector]]
Solar thermal power stations have been successfully operating in [[California]] commercially since the late 1980s, including the largest solar power plant of any kind, the 350 MW [[Solar Energy Generating Systems]]. [[Nevada Solar One]] is another 64MW plant which has recently opened.<ref>[http://www.lvbusinesspress.com/articles/2007/03/05/news/iq_12851348.txt Solar One is "go" for launch]</ref> Other parabolic trough power plants being proposed are two 50MW plants in [[Spain]], and a 100MW plant in [[Israel]].<ref>[http://www.isracast.com/Articles/Article.aspx?ID=71 Israeli company drives the largest solar plant in the world]</ref>
In terms of [[Ocean energy]], another third-generation technology, [[Portugal]] has the world's first commercial [[wave farm]], the ''Aguçadora Wave Park'', under construction in 2007. The farm will initially use three [[Pelamis Wave Energy Converter|Pelmis P-750]] machines generating 2.25 MW.<ref>[http://news.bbc.co.uk/1/hi/scotland/4805076.stm Sea machine makes waves in Europe] ''BBC News'', 15 March 2006.</ref> <ref>[http://news.bbc.co.uk/1/hi/scotland/4563077.stm Wave energy contract goes abroad] ''BBC News'', 19 May 2005.</ref> and costs are put at 8.5 million [[euro]]. Subject to successful operation, a further 70 million euro is likely to be invested before [[2009]] on a further 28 machines to generate 525 MW.<ref>[http://jn.sapo.pt/2006/05/12/economia_e_trabalho/primeiro_parque_mundial_ondas_povoa_.html Primeiro parque mundial de ondas na Póvoa de Varzim]</ref> Funding for a wave farm in [[Scotland]] was announced in February, 2007 by the [[Scottish Executive]], at a cost of over 4 million [[pound sterling|pounds]], as part of a £13 million funding packages for [[Renewable energy in Scotland#Wave power|ocean power in Scotland]]. The farm will be the world's largest with a capacity of 3 MW generated by four Pelamis machines.<ref>[http://news.bbc.co.uk/2/hi/uk_news/scotland/6377423.stm Orkney to get 'biggest' wave farm] ''BBC News'', 20 February 2007.</ref> (see also [[Wave farm]]).
In 2007, the world's first turbine to create commercial amounts of energy using [[tidal power]] was installed in the narrows of [[Strangford Lough]] in Ireland. The 1.2 MW underwater tidal electricity generator takes advantage of the fast tidal flow in the lough which can be up to 4[[m/s]]. Although the generator is powerful enough to power up to a thousand homes, the [[turbine]] has a minimal [[Environmental degradation|environmental impact]], as it is almost entirely submerged, and the rotors turn slowly enough that they pose no danger to [[wildlife]].<ref>[http://www.timesonline.co.uk/tol/news/environment/article3694859.ece Turbine technology is turning the tides into power of the future]</ref><ref>[http://www.renewableenergyworld.com/rea/news/story?id=52536 SeaGen Turbine Installation Completed]</ref>
Solar power panels that use [[nanotechnology]], which can create circuits out of individual silicon molecules, may cost half as much as traditional photovoltaic cells, according to executives and investors involved in developing the products. [[Nanosolar]] has secured more than $100 million from investors to build a factory for nanotechnology thin-film solar panels. The company's plant has a planned production capacity of 430 megawatts peak power of solar cells per year. Commercial production started and first panels have been shipped<ref>[http://www.nanosolar.com/blog3/2007/12/18/nanosolar-ships-first-panels/ Nanosolar ships first panels]</ref> to customers in late 2007.<ref>[http://www.azcentral.com/news/articles/0622-nanotech.html Solar power nanotechnology may cut cost in half, executives say]</ref>
==Energy efficiency==
Moving towards energy sustainability will require changes not only in the way energy is supplied, but in the way it is used, and reducing the amount of energy required to deliver various goods or services is essential. Opportunities for improvement on the demand side of the energy equation are as rich and diverse as those on the supply side, and often offer significant economic benefits.<ref>InterAcademy Council (2007). [http://www.interacademycouncil.net/Object.File/Master/12/053/Executive%20Summary.pdf ''Lighting the way: Toward a sustainable energy future'']</ref>
Renewable energy and [[efficient energy use|energy efficiency]] are sometimes said to be the “twin pillars” of sustainable energy policy. Both resources must be developed in order to stabilize and reduce carbon dioxide emissions. Efficiency slows down energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too fast, renewable energy development will chase a receding target. Likewise, unless clean energy supplies come online rapidly, slowing demand growth will only begin to reduce total emissions; reducing the carbon content of energy sources is also needed. Any serious vision of a sustainable energy economy thus requires commitments to both renewables and efficiency.<ref>American Council for an Energy-Efficient Economy (2007).
[http://aceee.org/store/proddetail.cfm?CFID=2957330&CFTOKEN=50269931&ItemID=432&CategoryID=7 ''The Twin Pillars of Sustainable Energy: Synergies between Energy Efficiency and Renewable Energy Technology and Policy''] Report E074.</ref>
Renewable energy (and energy efficiency) are no longer niche sectors that are promoted only by governments and environmentalists. The increased levels of investment and the fact that much of the capital is coming from more conventional financial actors suggest that sustainable energy options are now becoming mainstream.<ref>United Nations Environment Programme and New Energy Finance Ltd. (2007), p. 17.</ref>
[[Climate change]] concerns coupled with [[Oil price increases since 2003|high oil prices]] and increasing government support are driving increasing rates of investment in the sustainable energy industries, according to a trend analysis from the [[United Nations Environment Programme]]. According to [[UNEP]], global investment in sustainable energy in 2007 was higher than previous levels, with $148 billion of new money raised in 2007, an increase of 60% over 2006. Total financial transactions in sustainable energy, including acquisition activity, was $204 billion.<ref name=invest>[http://sefi.unep.org/fileadmin/media/sefi/docs/publications/Global_Trends_2008.pdf Global Trends in Sustainable Energy Investment 2008] p. 8.</ref>
Investment flows in 2007 broadened and diversified, making the overall picture one of greater breadth and depth of sustainable energy use. The mainstream capital markets are "now fully receptive to sustainable energy companies, supported by a surge in funds destined for clean energy investment".<ref name=invest/>
==Nuclear power==
It is said that nuclear has the potential to be sustainable, however, this is often qualified with the argument that there are serious challenges that must be dealt with before it can drastically increase its role.<ref>World Nuclear Association. [http://www.world-nuclear.org/sym/1997/bourd.htm Nuclear Power and Sustainable Development].</ref>
There are two types of nuclear power. "Fission" is used in all current nuclear power plants. [[Fusion power]] is the reaction that powers stars, including the sun, which is still being researched for use on earth. Both types create radioactive waste in the form of [[neutron activation|activated]] structural material, which is one of the sustainability issues.
Fission power's long-term sustainability depends on the amount of uranium and thorium that are available to be mined. Estimates for fuel reserves vary widely, but if [[breeder reactor]]s and fuel reprocessing are assumed, estimates tend to be tens of thousands of years or longer{{Fact|date=February 2008}} (uranium is approximately as common in Earth's crust as [[tin]] or [[zinc]] (2 ppm), and thorium as common as [[lead]] (6 ppm)).{{Fact|date=February 2008}}
Fusion power's long-term sustainability depends on whether or not affordable technology can be developed, and on the amount of [[lithium]] that is available to be mined (for deuterium-tritium fusion), or the amount of [[deuterium]], a hydrogen isotope, available in "[[heavy water]]" (for deuterium-deuterium fusion). Lithium is a reasonably common component of [[Earth]]'s crust, being about 10 times as common as [[thorium]] (65 ppm). Deuterium occurs in small concentrations wherever hydrogen is found (principally in [[water]]), at about 150 ppm. It can be extracted easily from seawater. Given the size of earth's [[ocean]]s, economically viable reserves of deuterium are for practical purposes unlimited.
===Technical sustainability of nuclear power===
Proponents, such as environmentalists [[James Lovelock]], [[Patrick Moore (environmentalist)|Patrick Moore]] ([[Greenpeace]] co-founder), [[Stewart Brand]] (creator of The [[Whole Earth Catalog]]), and [[Norris McDonald]] (president of the [[African American Environmentalist Association|AAEA]]), also claim that nuclear power is at least as environmentally friendly as traditional sources of renewable energy, making it part of the solution to [[global warming]] and the world's growing need for energy. They note that nuclear power plants produce little carbon dioxide emissions and point out that the radioactive waste produced is minimal and well-contained, especially compared to fossil fuels.<ref>Nuclear Energy Institute. [http://web.archive.org/web/20060425113422/http://www.nei.org/index.asp?catnum=2&catid=322 Prominent Environmentalists Support Nuclear Energy]</ref>
== See also ==
{{portal|Energy}}
{{Portal|Sustainable development|Sustainable development.svg}}
* [[Avoiding Dangerous Climate Change]]
* [[Ashden Awards]]
* [[Climate Change and Sustainable Energy Act 2006]]
* [[Energy Globe Awards]]
* [[Global warming]]
* [[Greasestock]]
* [[International Sustainable Energy Agency]]
* [[INFORSE]], International Network for Sustainable Energy
* [[Kyoto Protocol]]
* [[Institute for Sustainable Energy]]
* [[World energy resources and consumption]]
==References==
{{reflist|2}}
==External links==
*[http://www.spiegel.de/international/business/0,1518,druck-503701,00.html Europe: No. 1 in Sustainable Energy?]
*[http://www.ceem.unsw.edu.au/content/userDocs/NuclearMacGilletAl_IEEEPE0607.pdf IEEE power and energy magazine] - ''Is there a Sustainable Future for Nuclear Power?''
{{Environmental technology}}
[[Category:Energy economics]]
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