Editing Energy development (section)

== Renewable sources ==
{{Main|Renewable energy commercialization}}
[[File:2011- Renewable energy capacity - International Energy Agency.svg |thumb|Renewable energy capacity has steadily grown, led by [[Photovoltaic system|solar photovoltaic]] power.<ref name=IEA_202306>Source for data beginning in 2017: {{cite web |title=Renewable Energy Market Update Outlook for 2023 and 2024 |url=https://iea.blob.core.windows.net/assets/63c14514-6833-4cd8-ac53-f9918c2e4cd9/RenewableEnergyMarketUpdate_June2023.pdf |website=IEA.org |publisher=International Energy Agency (IEA) |archive-url=https://web.archive.org/web/20230711115355/https://iea.blob.core.windows.net/assets/63c14514-6833-4cd8-ac53-f9918c2e4cd9/RenewableEnergyMarketUpdate_June2023.pdf |archive-date=11 July 2023 |page=19 |date=June 2023 |quote=IEA. CC BY 4.0. |url-status=live}} ● Source for data through 2016: {{cite web |title=Renewable Energy Market Update / Outlook for 2021 and 2022 |url=https://iea.blob.core.windows.net/assets/18a6041d-bf13-4667-a4c2-8fc008974008/RenewableEnergyMarketUpdate-Outlookfor2021and2022.pdf |website=IEA.org |publisher=International Energy Agency |archive-url=https://web.archive.org/web/20230325084025/https://iea.blob.core.windows.net/assets/18a6041d-bf13-4667-a4c2-8fc008974008/RenewableEnergyMarketUpdate-Outlookfor2021and2022.pdf |archive-date=25 March 2023 |page=8 |date=May 2021 |url-status=live |quote=IEA. Licence: CC BY 4.0 }}</ref>]]
{{multiple image | total_width=225px 
| image2= 20211104 Percentage of electricity from fossil fuels, nuclear, renewables - biggest fossil fuel emitters.svg |caption2= The countries most reliant on fossil fuels for electricity vary widely on how great a percentage of that electricity is generated from renewables, leaving wide variation in renewables' growth potential.<ref name=BP-Ember_20211103>{{cite web |author1=Data: BP Statistical Review of World Energy, and Ember Climate |title=Electricity consumption from fossil fuels, nuclear and renewables, 2020 |url=https://ourworldindata.org/grapher/elec-mix-bar |website=OurWorldInData.org |publisher=Our World in Data consolidated data from BP and Ember |archive-url=https://web.archive.org/web/20211103100119/https://ourworldindata.org/grapher/elec-mix-bar |archive-date=3 November 2021 |date=3 November 2021 |url-status=live }}</ref>
}}
[[Renewable energy]] is generally defined as energy that comes from resources which are naturally replenished on a human timescale such as [[sunlight]], [[wind]], [[rain]], [[Tidal power|tides]], [[Wave power|waves]] and [[Geothermal energy|geothermal heat]]. Renewable energy replaces conventional fuels in four distinct areas: [[electricity generation]], [[Solar hot water|hot water]]/[[space heating]], [[Motor fuel|motor fuels]], and [[Stand-alone power system|rural (off-grid)]] energy services.

Including traditional biomass usage, about 19% of global energy consumption is accounted for by renewable resources.<ref>{{Cite web |title=Modern renewables – SDG7: Data and Projections – Analysis |url=https://www.iea.org/reports/sdg7-data-and-projections/modern-renewables |access-date=2024-02-04 |website=IEA |language=en-GB}}</ref> Wind powered energy production is being turned to as a prominent renewable energy source, increasing global wind power capacity by 12% in 2021.<ref>{{Cite journal |date=2022-11-01 |title=Renewable energy for sustainable development |url=https://www.sciencedirect.com/science/article/pii/S0960148122014215 |journal=Renewable Energy |language=en-US |volume=199 |pages=1145–1152 |doi=10.1016/j.renene.2022.09.065 |issn=0960-1481 |last1=Østergaard |first1=Poul Alberg |last2=Duic |first2=Neven |last3=Noorollahi |first3=Younes |last4=Kalogirou |first4=Soteris |bibcode=2022REne..199.1145O |url-access=subscription }}</ref> While not the case for all countries, 58% of sample countries linked renewable energy consumption to have a positive impact on economic growth.<ref>{{Cite journal |last1=Shahbaz |first1=Muhammad |last2=Raghutla |first2=Chandrashekar |last3=Chittedi |first3=Krishna Reddy |last4=Jiao |first4=Zhilun |last5=Vo |first5=Xuan Vinh |date=2020-09-15 |title=The effect of renewable energy consumption on economic growth: Evidence from the renewable energy country attractive index |url=https://www.sciencedirect.com/science/article/pii/S036054422031269X |journal=Energy |volume=207 |pages=118162 |doi=10.1016/j.energy.2020.118162 |bibcode=2020Ene...20718162S |issn=0360-5442}}</ref> At the national level, at least 30 nations around the world already have renewable energy contributing more than 20% of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond.[76]

Unlike other energy sources, renewable energy sources are not as restricted by geography. Additionally deployment of renewable energy is resulting in economic benefits as well as combating climate change. Rural electrification<ref>{{Cite journal |last1=Akbas |first1=Beste |last2=Kocaman |first2=Ayse Selin |last3=Nock |first3=Destenie |last4=Trotter |first4=Philipp A. |date=2022-03-01 |title=Rural electrification: An overview of optimization methods |url=https://www.sciencedirect.com/science/article/pii/S1364032121012004 |journal=Renewable and Sustainable Energy Reviews |volume=156 |pages=111935 |doi=10.1016/j.rser.2021.111935 |bibcode=2022RSERv.15611935A |issn=1364-0321|url-access=subscription }}</ref> has been researched on multiple sites and positive effects on commercial spending, appliance use, and general activities requiring electricity as energy.<ref>{{Cite journal |last1=Østergaard |first1=Poul Alberg |last2=Duic |first2=Neven |last3=Noorollahi |first3=Younes |last4=Kalogirou |first4=Soteris |date=2020-12-01 |title=Latest progress in Sustainable Development using renewable energy technology |url=https://www.sciencedirect.com/science/article/pii/S0960148120315494 |journal=Renewable Energy |volume=162 |pages=1554–1562 |doi=10.1016/j.renene.2020.09.124 |bibcode=2020REne..162.1554O |issn=0960-1481|url-access=subscription }}</ref> Renewable energy growth in at least 38 countries has been driven by the high electricity usage rates.<ref>{{Cite journal |last1=Lu |first1=Zhou |last2=Gozgor |first2=Giray |last3=Mahalik |first3=Mantu Kumar |last4=Padhan |first4=Hemachandra |last5=Yan |first5=Cheng |date=2022-08-01 |title=Welfare gains from international trade and renewable energy demand: Evidence from the OECD countries |url=https://www.sciencedirect.com/science/article/pii/S0140988322003085 |journal=Energy Economics |volume=112 |pages=106153 |doi=10.1016/j.eneco.2022.106153 |bibcode=2022EneEc.11206153L |issn=0140-9883}}</ref> International support for promoting renewable sources like solar and wind have continued grow.

While many renewable energy projects are large-scale, renewable technologies are also suited to [[rural]] and remote areas and [[Renewable energy in developing countries|developing countries]], where energy is often crucial in [[Human development (humanity)|human development]]. To ensure human development continues sustainably, governments around the world are beginning to research potential ways to implement renewable sources into their countries and economies. For example, the UK Government’s Department for Energy and Climate Change 2050 Pathways created a mapping technique to educate the public on land competition between energy supply technologies. <ref>{{Cite journal |last1=Bridge |first1=Gavin |last2=Bouzarovski |first2=Stefan |last3=Bradshaw |first3=Michael |last4=Eyre |first4=Nick |date=2013-02-01 |title=Geographies of energy transition: Space, place and the low-carbon economy |url=https://www.sciencedirect.com/science/article/pii/S0301421512009512 |journal=Energy Policy |volume=53 |pages=331–340 |doi=10.1016/j.enpol.2012.10.066 |bibcode=2013EnPol..53..331B |issn=0301-4215}}</ref> This tool provides users the ability to understand what the limitations and potential their surrounding land and country has in terms of energy production.

=== Hydroelectricity ===

[[File:ThreeGorgesDam-China2009.jpg|thumb| The 22,500 [[Megawatt|MW]] [[Three Gorges Dam]] in China – the [[List of conventional hydroelectric power stations#Hydroelectric power stations|world's largest]] hydroelectric power station]]

[[Hydroelectricity]]  is electric power generated by [[hydropower]]; the force of falling or flowing water. In 2015 hydropower generated 16.6% of the world's total electricity and 70% of all renewable electricity <ref>{{cite web|url=http://www.ren21.net/wp-content/uploads/2016/06/GSR_2016_Full_Report_REN21.pdf|access-date=2017-05-24|title=Renewables 2016: Global Status Report|url-status=live|archive-url=https://web.archive.org/web/20170525173336/http://www.ren21.net/wp-content/uploads/2016/06/GSR_2016_Full_Report_REN21.pdf|archive-date=2017-05-25}}</ref>{{page needed|date=May 2017}} and was expected to increase about 3.1% each year for the following 25 years.

Hydropower is produced in 150 countries, with the Asia-Pacific region generating 32 percent of global hydropower in 2010. China is the largest hydroelectricity producer, with 721 terawatt-hours of production in 2010, representing around 17 percent of domestic electricity use. There are now three hydroelectricity plants larger than 10 GW: the [[Three Gorges Dam]] in China, [[Itaipu Dam]] across the Brazil/Paraguay border, and [[Guri Dam]] in Venezuela.<ref name=wi2012>{{cite web |url=http://www.worldwatch.org/node/9527 |title=Use and Capacity of Global Hydropower Increases |author=Worldwatch Institute |date=January 2012 |url-status=dead |archive-url=https://web.archive.org/web/20140924062448/http://www.worldwatch.org/node/9527 |archive-date=2014-09-24 |access-date=2014-01-11 }}</ref>

The cost of hydroelectricity is relatively low, making it a competitive source of renewable electricity. The average cost of electricity from a hydro plant larger than 10 megawatts is 3 to 5 U.S. cents per kilowatt-hour.<ref name=wi2012/> Hydro is also a flexible source of electricity since plants can be ramped up and down very quickly to adapt to changing energy demands. However, damming interrupts the flow of rivers and can harm local ecosystems, and building large dams and reservoirs often involves displacing people and wildlife.<ref name=wi2012/> Once a hydroelectric complex is constructed, the project produces no direct waste, and has a considerably lower output level of the [[greenhouse gas]] [[carbon dioxide]] than [[fossil fuel]] powered energy plants.<ref name="REN21-2011">[http://www.ren21.net/Portals/97/documents/GSR/REN21_GSR2011.pdf Renewables 2011 Global Status Report, page 25, Hydropower] {{webarchive |url=https://web.archive.org/web/20120409013321/http://www.ren21.net/Portals/97/documents/GSR/REN21_GSR2011.pdf |date=April 9, 2012 }}, ''[[REN21]]'', published 2011, accessed 2011-11-7.</ref>

=== Wind ===
{{multiple image
 |direction = vertical
 |align = right
 |width = 218
 |image2=Global Wind Power Cumulative Capacity.svg
 |image1=Pretty flamingos - geograph.org.uk - 578705.jpg
 |caption2=[[Wind power by country|Global growth]] of wind power capacity
 |caption1=[[Burbo Bank Offshore Wind Farm]] in Northwest England
}}

[[Wind power]] harnesses the power of the wind to propel the blades of [[wind turbine]]s. These turbines cause the rotation of [[magnet]]s, which creates electricity. Wind towers are usually built together on [[wind farm]]s. There are [[List of offshore wind farms|offshore]] and [[List of onshore wind farms|onshore]] wind farms. [[Wind power by country|Global wind power capacity]] has expanded rapidly to 336 [[Gigawatt|GW]] in June 2014, and wind energy production was around 4% of total worldwide electricity usage, and growing rapidly.<ref name="wwea2014-halfyear">{{cite book |author=The World Wind Energy Association |title=2014 Half-year Report |year=2014|pages=1–8 |publisher=WWEA}}</ref>

Wind power is widely used in [[Wind power in the European Union|Europe]], [[Wind power in China|Asia]], and the [[Wind power in the United States|United States]].<ref name="Glob">[http://www.gwec.net/uploads/media/07-02_PR_Global_Statistics_2006.pdf Global wind energy markets continue to boom – 2006 another record year] {{webarchive|url=https://web.archive.org/web/20110407175732/http://www.gwec.net/uploads/media/07-02_PR_Global_Statistics_2006.pdf |date=2011-04-07 }} (PDF).</ref> Several countries have achieved relatively high levels of wind power penetration, such as 21% of stationary electricity production in [[Wind power in Denmark|Denmark]],<ref name="wwea">{{cite web 
 |publisher=[[World Wind Energy Association]]  |title=World Wind Energy Report 2010  |work=Report  |date=February 2011  |url= http://www.wwindea.org/home/images/stories/pdfs/worldwindenergyreport2010_s.pdf  |access-date=8 August 2011  |url-status=dead |archive-url= https://web.archive.org/web/20110904232058/http://www.wwindea.org/home/images/stories/pdfs/worldwindenergyreport2010_s.pdf 
 |archive-date=4 September 2011  }}</ref> 18% in [[Wind power in Portugal|Portugal]],<ref name="wwea"/> 16% in [[Wind power in Spain|Spain]],<ref name="wwea"/> 14% in [[Wind power in Ireland|Ireland]],<ref>{{cite web |url=http://www.eirgrid.com/renewables/ |title=Renewables |publisher=eirgrid.com |access-date=22 November 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110815202535/http://www.eirgrid.com/renewables/ |archive-date=15 August 2011 }}</ref> and 9% in [[Wind power in Germany|Germany]] in 2010.<ref name="wwea"/><ref name=ren212011>{{cite web|url=http://www.ren21.net/Portals/97/documents/GSR/GSR2011_Master18.pdf |title=Renewables 2011: Global Status Report |author=REN21 |year=2011 |url-status=dead |archive-url=https://web.archive.org/web/20110905003859/http://www.ren21.net/Portals/97/documents/GSR/GSR2011_Master18.pdf |archive-date=2011-09-05 |author-link=REN21 }}</ref>{{rp|11}} By 2011, at times over 50% of electricity in Germany and Spain came from wind and solar power.<ref>{{cite web|url=https://www.theguardian.com/environment/2012/may/28/solar-power-world-record-germany|title=This page has been removed - News - The Guardian|work=The Guardian|url-status=live|archive-url=https://web.archive.org/web/20170226071255/https://www.theguardian.com/environment/2012/may/28/solar-power-world-record-germany|archive-date=2017-02-26}}</ref><ref>[http://www.wind-works.org/FeedLaws/Spain/SpainRenewableEnergyandHighPenetration.html Spain Renewable Energy and High Penetration] {{webarchive |url=https://web.archive.org/web/20120609235738/http://www.wind-works.org/FeedLaws/Spain/SpainRenewableEnergyandHighPenetration.html |date=June 9, 2012 }}</ref> As of 2011, 83 countries around the world are using wind power on a commercial basis.<ref name=ren212011/>{{rp|11}}

Many of the [[List of onshore wind farms#Largest operational onshore wind farms|world's largest onshore wind farms]] are located in the [[Wind power in the United States|United States]], [[Wind power in China|China]], and [[Wind power in India|India]]. Most of the [[List of offshore wind farms|world's largest offshore wind farms]] are located in [[Wind power in Denmark|Denmark]], [[Wind power in Germany|Germany]] and the [[Wind power in the United Kingdom|United Kingdom]]. The two largest offshore wind farm are currently the 630 [[Megawatt|MW]] [[London Array]] and [[Gwynt y Môr]].

{| class="wikitable"
|+ Large onshore wind farms
|-
! Wind farm
! Current<br />capacity<br />([[Megawatt|MW]])
! Country
! Notes
|-
| [[Alta Wind Energy Center|Alta (Oak Creek-Mojave)]] || align=center | 1,320 || {{Flagu|USA}} ||<ref name=terragen>[http://www.terra-genpower.com/News/Terra-Gen-Power-Announces-Closing-of-$650-Million-.aspx Terra-Gen Press Release] {{webarchive|url=https://web.archive.org/web/20120510173856/http://www.terra-genpower.com/News/Terra-Gen-Power-Announces-Closing-of-%24650-Million-.aspx |date=2012-05-10 }}, 17 April 2012</ref>
|-
| [[Jaisalmer Wind Park]] || align=center | 1,064 || {{Flagu|India}} ||<ref name=Jaisalmer>{{cite news|url=http://www.business-standard.com/india/news/suzlon-creates-country/s-largest-wind-park/164779/on|title=Suzlon creates country's largest wind park|author=BS Reporter|date=11 May 2012|work=business-standard.com|url-status=live|archive-url=https://web.archive.org/web/20121001062608/http://www.business-standard.com/india/news/suzlon-creates-country/s-largest-wind-park/164779/on|archive-date=1 October 2012}}</ref>
|-
| [[Roscoe Wind Farm]] || align=center | 781 || {{Flagu|USA}} ||<ref>{{cite web|url=http://www.renewableenergyworld.com/rea/news/story?id=53650|title=Top News|website=www.renewableenergyworld.com|access-date=4 May 2018|url-status=live|archive-url=https://web.archive.org/web/20160105145506/http://www.renewableenergyworld.com/rea/news/story?id=53650|archive-date=5 January 2016}}</ref>
|-
| [[Horse Hollow Wind Energy Center]] || align=center | 735 || {{Flagu|USA}} ||<ref name=drilling/><ref name=tex>[http://www.awea.org/projects/Projects.aspx?s=Texas AWEA: U.S. Wind Energy Projects – Texas] {{webarchive |url=https://web.archive.org/web/20071229033413/http://www.awea.org/projects/Projects.aspx?s=Texas |date=December 29, 2007 }}</ref>
|-
| [[Capricorn Ridge Wind Farm]] || align=center | 662 || {{Flagu|USA}} ||<ref name=drilling>{{cite web|url=http://www.renewableenergyworld.com/rea/news/article/2009/02/drilling-down-what-projects-made-2008-such-a-banner-year-for-wind-power|title=Drilling Down: What Projects Made 2008 Such a Banner Year for Wind Power?|work=renewableenergyworld.com|url-status=live|archive-url=https://web.archive.org/web/20110715173218/http://www.renewableenergyworld.com/rea/news/article/2009/02/drilling-down-what-projects-made-2008-such-a-banner-year-for-wind-power|archive-date=2011-07-15}}</ref><ref name=tex/>
|-
| [[Fântânele-Cogealac Wind Farm]] || align=center | 600 || {{Flagu|Romania}} ||<ref name=cez>{{cite web|url=http://www.cez.cz/en/cez-group/media/press-releases/4051.html|title=CEZ Group - The Largest Wind Farm in Europe Goes Into Trial Operation|author1=FG Forrest|author2=a. s.|author3=fg {zavináč } fg {tečka} cz - Content Management System - Edee CMS; SYMBIO Digital, s. r. o. - Webdesign|work=cez.cz|url-status=live|archive-url=https://web.archive.org/web/20150701163434/http://www.cez.cz/en/cez-group/media/press-releases/4051.html|archive-date=2015-07-01}}</ref>
|-
| [[Fowler Ridge Wind Farm]] || align=center | 599 || {{Flagu|USA}} ||<ref name=ind>[http://www.awea.org/projects/Projects.aspx?s=Indiana AWEA: U.S. Wind Energy Projects – Indiana] {{webarchive|url=https://web.archive.org/web/20100918151714/http://www.awea.org/projects/Projects.aspx?s=Indiana |date=2010-09-18 }}</ref>
|}

=== Solar ===
{{Excerpt|Solar Energy|only=paragraphs}}

=== Biofuels ===
{{Main|Biofuel|Sustainable biofuel}}
{{multiple image|direction = vertical | align = right | width = 225 |image1=Soybeanbus.jpg|image2=EthanolPetrol.jpg|caption1=A bus fueled by [[biodiesel]]|caption2=Information on pump regarding [[ethanol fuel]] blend up to&nbsp;10%, [[California]]}}

A biofuel is a [[fuel]] that contains energy from geologically recent [[carbon fixation]]. These fuels are produced from [[living organisms]]. Examples of this [[carbon fixation]] occur in [[plants]] and [[microalgae]]. These fuels are made by a [[biomass]] conversion (biomass refers to recently living organisms, most often referring to [[plants]] or plant-derived materials). This biomass can be converted to convenient energy containing substances in three different ways: thermal conversion, chemical conversion, and biochemical conversion. This biomass conversion can result in fuel in [[solid]], [[liquid]], or [[gas]] form. This new biomass can be used for biofuels. Biofuels have increased in popularity because of rising [[oil prices]] and the need for [[energy security]].

[[Bioethanol]] is an [[Alcohol (chemistry)|alcohol]] made by [[Ethanol fermentation|fermentation]], mostly from [[carbohydrate]]s produced in [[sugar]] or [[starch]] crops such as [[Maize|corn]] or [[sugarcane]]. [[cellulose|Cellulosic biomass]], derived from non-food sources, such as trees and grasses, is also being developed as a [[feedstock]] for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a [[gasoline]] [[Fuel additive|additive]] to increase octane and improve vehicle emissions. Bioethanol is widely used in the [[Biofuel in the United States|USA]] and in [[Ethanol fuel in Brazil|Brazil]]. Current plant design does not provide for converting the [[lignin]] portion of plant raw materials to fuel components by fermentation.

[[Biodiesel]] is made from [[vegetable oil]]s and [[animal fat]]s. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a [[diesel fuel|diesel]] additive to reduce levels of particulates, [[carbon monoxide]], and [[hydrocarbon]]s from diesel-powered vehicles. Biodiesel is produced from oils or fats using [[transesterification]] and is the most common biofuel in Europe. However, research is underway on producing renewable fuels from [[Renewable fuels by decarboxylation|decarboxylation]]<ref>{{cite journal|title = Continuous catalytic deoxygenation of model and algal lipids to fuel-like hydrocarbons over Ni–Al layered double hydroxide|doi=10.1016/j.cattod.2014.12.004|volume=258|pages=284–293|journal=Catalysis Today|author=Santillan-Jimenez Eduardo|year = 2015}}</ref>

In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17% from 2009,<ref name=Biofuels2010>{{cite web|url=http://www.worldwatch.org/biofuels-make-comeback-despite-tough-economy|title=Biofuels Make a Comeback Despite Tough Economy|publisher=[[Worldwatch Institute]]|date=2011-08-31|access-date=2011-08-31|url-status=dead|archive-url=https://web.archive.org/web/20120530232916/http://www.worldwatch.org/biofuels-make-comeback-despite-tough-economy|archive-date=2012-05-30}}</ref> and biofuels provided 2.7% of the world's fuels for [[road transport]], a contribution largely made up of ethanol and biodiesel.{{citation needed|date=September 2012}} Global [[ethanol fuel]] production reached 86 billion liters (23 billion gallons US) in 2010, with the United States and Brazil as the world's top producers, accounting together for 90% of global production. The world's largest biodiesel producer is the [[European Union]], accounting for 53% of all biodiesel production in 2010.<ref name=Biofuels2010/> As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states or provinces.<ref name=ren212011/>{{rp|13–14}} The [[International Energy Agency]] has a goal for biofuels to meet more than a quarter of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal.<ref>{{cite web |url=http://www.iea.org/publications/freepublications/publication/biofuels_roadmap.pdf |year=2011 |title=Technology Roadmap, Biofuels for Transport |url-status=live |archive-url=https://web.archive.org/web/20140722231200/http://www.iea.org/publications/freepublications/publication/biofuels_roadmap.pdf |archive-date=2014-07-22 }}</ref>

=== Geothermal ===
{{Main|Geothermal energy}}
[[File:NesjavellirPowerPlant edit2.jpg|thumb|Steam rising from the [[Nesjavellir Geothermal Power Station]] in [[Iceland]]]]

Geothermal energy is [[thermal energy]] generated and stored in the Earth. Thermal energy is the energy that determines the [[temperature]] of matter. The geothermal energy of the Earth's [[Crust (geology)|crust]] originates from the original formation of the planet (20%) and from [[radioactive decay]] of minerals (80%).<ref name=ucsusa>[http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-geothermal-energy-works.html How Geothermal energy works] {{webarchive|url=https://web.archive.org/web/20140925080922/http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-geothermal-energy-works.html |date=2014-09-25 }}. Ucsusa.org. Retrieved on 2013-04-24.</ref>  The [[geothermal gradient]], which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of [[heat]] from the core to the surface. The adjective ''geothermal'' originates from the Greek roots ''γη (ge)'', meaning earth, and ''θερμος (thermos)'', meaning hot.

[[Earth's internal heat budget|Earth's internal heat]] is thermal energy generated from [[radioactive decay]] and continual heat loss from Earth's formation. Temperatures at the [[core mantle boundary|core-mantle boundary]] may reach over 4000&nbsp;°C (7,200&nbsp;°F).<ref>{{cite journal | author = Lay T., Hernlund J., Buffett B. A. | year = 2008 | title = Core–mantle boundary heat flow | journal = Nature Geoscience | volume = 1 | issue = 1| pages = 25–32 | bibcode = 2008NatGe...1...25L | doi = 10.1038/ngeo.2007.44 }}</ref> The high temperature and pressure in Earth's interior cause some rock to melt and solid [[mantle (geology)|mantle]] to behave plastically, resulting in portions of [[mantle convection|mantle convecting]] upward since it is lighter than the surrounding rock.  Rock and water is heated in the crust, sometimes up to 370&nbsp;°C (700&nbsp;°F).<ref>{{cite web|last=Nemzer|first=J|title=Geothermal heating and cooling|url=http://www.geothermal.marin.org/|url-status=dead|archive-url=https://web.archive.org/web/19980111021839/http://geothermal.marin.org/|archive-date=1998-01-11}}</ref>

From [[hot springs]], geothermal energy has been used for bathing since [[Paleolithic]] times and for [[space heating]] since ancient Roman times, but it is now better known for [[electricity generation]]. Worldwide, 11,400 [[megawatts]] (MW) of geothermal power is online in 24 countries in 2012.<ref>{{cite web |url=http://www.bp.com/en/global/corporate/about-bp/statistical-review-of-world-energy-2013/review-by-energy-type/renewable-energy/geothermal-capacity.html |title=Geothermal capacity &#124; About BP &#124; BP Global |publisher=Bp.com |access-date=2013-10-05 |url-status=live |archive-url=https://web.archive.org/web/20131006185306/http://www.bp.com/en/global/corporate/about-bp/statistical-review-of-world-energy-2013/review-by-energy-type/renewable-energy/geothermal-capacity.html |archive-date=2013-10-06 }}</ref>  An additional 28 gigawatts of direct [[geothermal heating]] capacity is installed for district heating, space heating, spas, industrial processes, desalination and agricultural applications in 2010.<ref name="IPCC">Fridleifsson, Ingvar B.; Bertani, Ruggero; Huenges, Ernst; Lund, John W.; Ragnarsson, Arni; Rybach, Ladislaus (2008-02-11), O. Hohmeyer and T. Trittin, ed., The possible role and contribution of geothermal energy to the mitigation of climate change (pdf), IPCC Scoping Meeting on Renewable Energy Sources, Luebeck, Germany, pp. 59–80, retrieved 2009-04-06</ref>

Geothermal power is cost effective, reliable, sustainable, and environmentally friendly,<ref>Glassley, William E. (2010). ''Geothermal Energy: Renewable Energy and the Environment'', CRC Press, {{ISBN|9781420075700}}.</ref> but has historically been limited to areas near [[tectonic plate boundaries]]. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation. Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels. As a result, geothermal power has the potential to help mitigate [[global warming]] if widely deployed in place of fossil fuels.

The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, [[energy subsidies|subsidies]], and interest rates. Pilot programs like EWEB's customer opt in Green Power Program <ref>[http://www.eweb.org/greenpower Green Power] {{webarchive|url=https://web.archive.org/web/20141015040912/http://www.eweb.org/greenpower |date=2014-10-15 }}. eweb.org</ref> show that customers would be willing to pay a little more for a renewable energy source like geothermal. But as a result of government assisted research and industry experience, the cost of generating geothermal power has decreased by 25% over the past two decades.<ref>{{Citation|last=Cothran|first=Helen|title=Energy Alternatives|year=2002|publisher=Greenhaven Press|isbn=978-0737709049}}</ref> In 2001, geothermal energy cost between two and ten US cents per kWh.<ref>{{cite journal|last=Fridleifsson|first=Ingvar|title= Geothermal energy for the benefit of the people|doi=10.1016/S1364-0321(01)00002-8|volume=5|issue=3|journal=Renewable and Sustainable Energy Reviews|pages=299–312|year=2001|bibcode=2001RSERv...5..299F |citeseerx=10.1.1.459.1779}}</ref>

=== Oceanic ===
{{Main|Marine energy}}


'''Marine Renewable Energy (MRE)''' or marine power (also sometimes referred to as ocean energy, ocean power, or marine and hydrokinetic energy) refers to the energy carried by the mechanical energy of [[Ocean wave|ocean waves]], currents, and [[Tide|tides]], shifts in [[salinity]] gradients, and [[Ocean thermal energy|ocean temperature differences]]. MRE has the potential to become a reliable and renewable energy source because of the cyclical nature of the oceans'''.'''<ref>{{Cite journal |last1=Caballero |first1=Mariah D. |last2=Gunda |first2=Thushara |last3=McDonald |first3=Yolanda J. |date=2023-09-01 |title=Energy justice & coastal communities: The case for Meaningful Marine Renewable Energy Development |journal=Renewable and Sustainable Energy Reviews |volume=184 |pages=113491 |doi=10.1016/j.rser.2023.113491 |issn=1364-0321|doi-access=free |bibcode=2023RSERv.18413491C }}</ref> The movement of water in the world's oceans creates a vast store of [[kinetic energy]] or energy in motion. This energy can be harnessed to [[Electricity generation|generate]] electricity to power homes, transport, and industries.

The term marine energy encompasses both [[wave power]], i.e. power from surface waves, and [[tidal power]], i.e. obtained from the kinetic energy of large bodies of moving water. [[Offshore wind power]] is not a form of marine energy, as wind power is derived from the wind, even if the [[Wind turbine|wind turbines]] are placed over water. The oceans have a tremendous amount of energy and are close to many if not most concentrated populations. Ocean energy has the potential to provide a substantial amount of new [[renewable energy]] around the world.<ref>{{Cite journal |date=2009 |title=Ocean Energy |url=https://doi.org/10.1007/978-3-540-77932-2 |journal=SpringerLink |language=en |doi=10.1007/978-3-540-77932-2|isbn=978-3-540-77931-5 |url-access=subscription }}</ref>

Marine energy technology is in its first stage of development. To be developed, MRE needs efficient methods of storing, transporting, and capturing ocean power, so it can be used where needed.<ref>{{Cite book |last=Thorson |first=J |title=Unlocking the potential of marine energy using hydrogen generation technologies |publisher=National Renewable Energy Laboratory. |year=2022}}</ref> Over the past year, countries around the world have started implementing market strategies for MRE to commercialize. Canada and China introduced incentives, such as [[Feed-in tariff|feed-in tariffs (FiTs)]], which are above-market prices for MRE that allow investors and project developers a stable income. Other financial strategies consist of subsidies, grants, and funding from [[Public–private partnership|public-private partnerships (PPPs)]]. China alone approved 100 ocean projects in 2019.<ref>{{Cite journal |last=Ni |first=Na |date=2023-04-01 |title=The current state on China's marine energy industry policy |journal=IOP Conference Series: Earth and Environmental Science |volume=1171 |issue=1 |pages=012025 |doi=10.1088/1755-1315/1171/1/012025 |issn=1755-1307|doi-access=free |bibcode=2023E&ES.1171a2025N }}</ref> Portugal and Spain recognize the potential of MRE in accelerating [[decarbonization]], which is fundamental to meeting the goals of the [[Paris Agreement]]. Both countries are focusing on solar and offshore wind [[Auction|auctions]] to attract private investment, ensure cost-effectiveness, and accelerate MRE growth. <ref>{{Cite journal |last1=Vieira |first1=Mário |last2=Macedo |first2=Ana |last3=Alvarenga |first3=António |last4=Lafoz |first4=Marcos |last5=Villalba |first5=Isabel |last6=Blanco |first6=Marcos |last7=Rojas |first7=Rodrigo |last8=Romero-Filgueira |first8=Alejandro |last9=García-Mendoza |first9=Adriana |last10=Santos-Herran |first10=Miguel |last11=Alves |first11=Marco |date=January 2024 |title=What future for marine renewable energy in Portugal and Spain up to 2030? Forecasting plausible scenarios using general morphological analysis and clustering techniques |journal=Energy Policy |volume=184 |pages=113859 |doi=10.1016/j.enpol.2023.113859 |issn=0301-4215|doi-access=free |bibcode=2024EnPol.18413859V |hdl=10362/159623 |hdl-access=free }}</ref> Ireland sees MRE as a key component to reduce its carbon footprint. The Offshore Renewable Energy Development Plan (OREDP) supports the exploration and development of the country's significant offshore energy potential. <ref>{{Cite web |title=About |url=https://www.oceanenergyireland.com/about/ |access-date=2024-03-12 |website=Ocean Energy Ireland}}</ref> Additionally, Ireland has implemented the Renewable Electricity Support Scheme (RESS) which includes auctions designed to provide financial support for communities, increase technology diversity, and guarantee [[energy security]]. <ref>{{Cite web |date=2019-12-20 |title=Renewable Electricity Support Scheme (RESS) |url=https://www.gov.ie/en/publication/36d8d2-renewable-electricity-support-scheme/ |access-date=2024-03-12 |website=www.gov.ie |language=en}}</ref>

However, while research is increasing, there have been concerns associated with threats to marine mammals, habitats, and potential changes to [[Ocean current|ocean currents.]] MRE can be a renewable energy source for coastal communities helping their transition from fossil fuel, but researchers are calling for a better understanding of its environmental impacts. <ref>{{Cite journal |last1=Newman |first1=Sarah F. |last2=Bhatnagar |first2=Dhruv |last3=O'Neil |first3=Rebecca S. |last4=Reiman |first4=Andy P. |last5=Preziuso |first5=Danielle C. |last6=Robertson |first6=Bryson |date=2022-09-30 |title=Evaluating the resilience benefits of marine energy in microgrids |url=https://marineenergyjournal.org/imej/article/view/120 |journal=International Marine Energy Journal |language=en |volume=5 |issue=2 |pages=143–150 |doi=10.36688/imej.5.143-150 |issn=2631-5548}}</ref> Because ocean-energy areas are often isolated from both fishing and sea traffic, these zones may provide shelter from humans and predators for some marine species. MRE devices can be an ideal home for many [[fish]], [[crayfish]], [[Mollusca|mollusks]], and [[Barnacle|barnacles]]; and may also indirectly affect [[Seabird|seabirds]], and [[Marine mammal|marine mammals]] because they feed on those species. Similarly, such areas may create an "[[Artificial reef|artificial reef effect]]" by boosting biodiversity nearby. [[Noise pollution]] generated from the technology is limited, also causing fish and mammals living in the area of the installation to return. <ref>{{Cite web |title=Ocean energy: An important ally in the fight against climate change |url=https://impact.economist.com/ocean/ocean-and-climate/ocean-energy-an-important-ally-in-the-fight-against-climate-change |access-date=2024-02-27 |website=impact.economist.com |language=en-gb}}</ref> In the most recent State of Science Report about MRE, the authors claim that there is no evidence for fish, mammals, or seabirds to be injured by either collision, noise pollution, or the electromagnetic field. The uncertainty of its environmental impact comes from the low quantity of MRE devices in the ocean today where data is collected. <ref>{{Cite web |title=Environmental Effects of Marine Renewable Energy: the 2020 State of the Science Report {{!}} Tethys |url=https://tethys.pnnl.gov/stories/environmental-effects-marine-renewable-energy-2020-state-science-report |access-date=2024-02-27 |website=tethys.pnnl.gov}}</ref>

=== 100% renewable energy ===
{{Main|100% renewable energy}}

The incentive to use 100% renewable energy, for electricity, transport, or even total primary energy supply globally, has been motivated by [[global warming]] and other ecological as well as economic concerns. [[Renewable energy commercialization|Renewable energy use]] has grown much faster than anyone anticipated.<ref name=pg11>{{cite web |url=http://www.renewableenergyworld.com/rea/news/article/2013/04/100-percent-renewable-vision-building?amp;buffer_share=fdc06 |title=100 Percent Renewable Vision Building |author=Paul Gipe |date=4 April 2013 |work=Renewable Energy World |url-status=live |archive-url=https://web.archive.org/web/20141006104925/http://www.renewableenergyworld.com/rea/news/article/2013/04/100-percent-renewable-vision-building?amp;buffer_share=fdc06 |archive-date=6 October 2014 }}</ref> The [[Intergovernmental Panel on Climate Change]] has said that there are few fundamental technological limits to integrating a portfolio of renewable energy technologies to meet most of total global energy demand.<ref name="IPCC 2011 17">{{cite web|url=http://srren.ipcc-wg3.de/report/IPCC_SRREN_SPM.pdf |title=Special Report on Renewable Energy Sources and Climate Change Mitigation |author=IPCC |year=2011 |work=Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA |page=17 |url-status=dead |archive-url=https://web.archive.org/web/20140111081913/http://srren.ipcc-wg3.de/report/IPCC_SRREN_SPM.pdf |archive-date=2014-01-11 }}</ref> At the national level, at least 30 nations around the world already have renewable energy contributing more than 20% of energy supply.  Also, [[Stephen W. Pacala]] and [[Robert H. Socolow]] have developed a series of "[[stabilization wedges]]" that can allow us to maintain our quality of life while avoiding catastrophic climate change, and "renewable energy sources," in aggregate, constitute the largest number of their "wedges."<ref name=Pacala>{{cite journal|url=http://www.princeton.edu/mae/people/faculty/socolow/Science-2004-SW-1100103-PAPER-AND-SOM.pdf|title=Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies|author1-link=Stephen W. Pacala|author1=S. Pacala|author2=R. Socolow|journal=Science|year=2004|volume=305|issue=5686|pages=968–972|publisher=Science Vol. 305|doi=10.1126/science.1100103|pmid=15310891|bibcode=2004Sci...305..968P|s2cid=2203046|url-status=live|archive-url=https://web.archive.org/web/20150812230420/http://www.princeton.edu/mae/people/faculty/socolow/Science-2004-SW-1100103-PAPER-AND-SOM.pdf|archive-date=2015-08-12}}</ref>

[[Mark Z. Jacobson]] says producing all new energy with [[wind power]], [[solar power]],  and [[hydropower]] by 2030 is feasible and existing energy supply arrangements could be replaced by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Jacobson says that energy costs with a wind, solar, water system should be similar to today's energy costs.<ref name=enpol2011>{{cite web |url=http://www.stanford.edu/group/efmh/jacobson/Articles/I/DJEnPolicyPt2.pdf |title=Providing all global energy with wind, water, and solar power, Part II: Reliability, system and transmission costs, and policies |author1=Mark A. Delucchi |author2=Mark Z. Jacobson |year=2011 |volume=39 |work=Energy Policy |pages=1170–1190 |publisher=Elsevier Ltd. |url-status=live |archive-url=https://web.archive.org/web/20120616162420/http://www.stanford.edu/group/efmh/jacobson/Articles/I/DJEnPolicyPt2.pdf |archive-date=2012-06-16 }}</ref>

Similarly, in the United States, the independent National Research Council has noted that "sufficient domestic renewable resources exist to allow renewable electricity to play a significant role in future electricity generation and thus help confront issues related to climate change, energy security, and the escalation of energy costs ... Renewable energy is an attractive option because renewable resources available in the United States, taken collectively, can supply significantly larger amounts of electricity than the total current or projected domestic demand." .<ref name=NRC>{{cite book|url=http://www.nap.edu/catalog.php?record_id=12619|title=Electricity from Renewable Resources: Status, Prospects, and Impediments|author=National Research Council|year=2010|pages=4|publisher=National Academies of Science|url-status=live|archive-url=https://web.archive.org/web/20140327124031/http://www.nap.edu/catalog.php?record_id=12619|archive-date=2014-03-27|doi=10.17226/12619|isbn=978-0-309-13708-9}}</ref>

Critics of the "100% renewable energy" approach include [[Vaclav Smil]] and [[James E. Hansen]]. Smil and Hansen are concerned about the [[variable renewable energy|variable output]] of solar and wind power, but [[Amory Lovins]] argues that the [[electricity grid]] can cope, just as it routinely backs up nonworking coal-fired and nuclear plants with working ones.<ref name=lovi12>{{cite journal |url=http://www.foreignaffairs.com/articles/137246/amory-b-lovins/a-farewell-to-fossil-fuels |title=A Farewell to Fossil Fuels |author=Amory Lovins |date=March–April 2012 |journal=Foreign Affairs |volume=329 |issue=5997 |pages=1292–1294 |url-status=live |archive-url=https://web.archive.org/web/20120707031832/http://www.foreignaffairs.com/articles/137246/amory-b-lovins/a-farewell-to-fossil-fuels |archive-date=2012-07-07 |bibcode=2010Sci...329.1292H |doi=10.1126/science.1195449 |pmid=20829473 |s2cid=206529026 |url-access=subscription }}</ref>

Google spent $30 million on their "Renewable Energy Cheaper than Coal" project to develop renewable energy and stave off catastrophic climate change. The project was cancelled after concluding that a best-case scenario for rapid advances in renewable energy could only result in emissions 55 percent below the fossil fuel projections for 2050.<ref>{{cite web|url=https://spectrum.ieee.org/what-it-would-really-take-to-reverse-climate-change|title=What It Would Really Take to Reverse Climate Change|date=2014-11-18|website=[[IEEE]]|access-date=4 May 2018|url-status=live|archive-url=https://web.archive.org/web/20161124081052/https://spectrum.ieee.org/energy/renewables/what-it-would-really-take-to-reverse-climate-change|archive-date=24 November 2016}}</ref>