View source for Concentrated solar power

{{Short description|Use of mirror or lens assemblies to heat a working fluid for electricity generation}}
{{Distinguish|concentrator photovoltaics}}
{{Use dmy dates|date=January 2021}}
[[File:Crescent Dunes Solar December 2014.JPG|thumb|A [[solar power tower]] at [[Crescent Dunes Solar Energy Project]] concentrating light via 10,000 mirrored [[heliostat]]s spanning {{convert|13000000|sqft|km2|2|abbr=on|round=|spell=in}}.|alt=An areal view of a large circle of thousands of bluish mirrors in a tan desert]]
[[File:Ivanpah Solar Power Facility (2).jpg|thumb|The three towers of the [[Ivanpah Solar Power Facility]] ]]
[[File:Solar Plant kl.jpg|thumb|Part of the 354&nbsp;MW [[SEGS]] solar complex in northern [[San Bernardino County, California]] ]]
[[File:KhiSolarOneBirdView.jpg|thumb|Bird's eye view of [[Khi Solar One]], [[South Africa]] ]]'''Concentrated solar power''' ('''CSP''', also known as '''concentrating solar power''', '''concentrated solar thermal''') systems generate [[solar power]] by using mirrors or lenses to concentrate a large area of sunlight into a receiver.<ref name=":0">{{Cite web|url=https://www.solarpaces.org/how-csp-works/|title=How CSP Works: Tower, Trough, Fresnel or Dish|date=June 12, 2018|website=SolarPACES|access-date=November 29, 2019}}</ref>  [[Electricity]] is generated when the concentrated light is converted to heat ([[solar thermal energy]]), which drives a [[heat engine]] (usually a [[steam turbine]]) connected to an electrical [[power generator]]<ref>{{cite journal |last1=Boerema |first1=Nicholas |last2=Morrison |first2=Graham |last3=Taylor |first3=Robert |last4=Rosengarten |first4=Gary |date=1 November 2013 |title=High temperature solar thermal central-receiver billboard design |journal=Solar Energy |volume=97 |pages=356–368 |doi=10.1016/j.solener.2013.09.008|bibcode=2013SoEn...97..356B }}</ref><ref>{{cite journal |last1=Law |first1=Edward W. |last2=Prasad |first2=Abhnil A. |last3=Kay |first3=Merlinde |last4=Taylor |first4=Robert A. |date=1 October 2014 |title=Direct normal irradiance forecasting and its application to concentrated solar thermal output forecasting – A review |journal=Solar Energy |volume=108 |pages=287–307 |doi=10.1016/j.solener.2014.07.008|bibcode=2014SoEn..108..287L }}</ref><ref>{{cite journal |last1=Law |first1=Edward W. |last2=Kay |first2=Merlinde |last3=Taylor |first3=Robert A. |date=1 February 2016 |title=Calculating the financial value of a concentrated solar thermal plant operated using direct normal irradiance forecasts |journal=Solar Energy |volume=125 |pages=267–281 |doi=10.1016/j.solener.2015.12.031|bibcode=2016SoEn..125..267L }}</ref> or powers a [[thermochemical]] reaction.<ref name="Sunshine to Petrol">{{cite web |title=Sunshine to Petrol |url=http://energy.sandia.gov/wp/wp-content/gallery/uploads/S2P_SAND2009-5796P.pdf |publisher=Sandia National Laboratories |access-date=11 April 2013 |archive-date=19 February 2013 |archive-url=https://web.archive.org/web/20130219194404/http://energy.sandia.gov/wp/wp-content/gallery/uploads/S2P_SAND2009-5796P.pdf }}</ref><ref name="SunShot">{{cite web |title=Integrated Solar Thermochemical Reaction System |url=http://www1.eere.energy.gov/solar/sunshot/csp_sunshotrnd_pnnl.html |archive-url=https://web.archive.org/web/20130415082843/http://www1.eere.energy.gov/solar/sunshot/csp_sunshotrnd_pnnl.html |archive-date=2013-04-15 |website=U.S. Department of Energy |access-date=11 April 2013}}</ref><ref name="NYT41013">{{cite news |title=New Solar Process Gets More Out of Natural Gas |url=https://www.nytimes.com/2013/04/11/business/energy-environment/new-solar-process-gets-more-out-of-natural-gas.html |access-date=11 April 2013 |newspaper=The New York Times |date=10 April 2013 |first=Matthew L. |last=Wald }}</ref>

As of 2021, global installed capacity of concentrated solar power stood at 6.8 GW.<ref name="chinCSP"/> As of 2023, the total was 8.1 GW, with the inclusion of three new CSP projects in construction in China<ref name="auto">{{Cite web |title=China |url=https://www.solarpaces.org/worldwide-csp/csp-potential-solar-thermal-energy-by-member-nation/china/ |access-date=2023-08-12 |website=SolarPACES |language=en-US}}</ref> and in Dubai in the UAE.<ref name="auto"/> The U.S.-based National Renewable Energy Laboratory (NREL), which maintains a global database of CSP plants, counts 6.6 GW of operational capacity and another 1.5 GW under construction.<ref>{{Cite web |title=CSP Projects Around the World |url=https://www.solarpaces.org/csp-technologies/csp-projects-around-the-world/ |access-date=2023-05-15 |website=SolarPACES |language=en-US}}</ref>

== Comparison between CSP and other electricity sources ==
As a thermal energy generating power station, CSP has more in common with [[thermal power station]]s such as coal, gas, or geothermal. A CSP plant can incorporate [[thermal energy storage]], which stores energy either in the form of [[sensible heat]] or as [[latent heat]] (for example, using [[molten salt]]), which enables these plants to continue supplying electricity whenever it is needed, day or night.<ref name=chcsp>{{cite web |url=https://www.solarpaces.org/wp-content/uploads/2024/02/Blue-Book-of-Chinas-Concentrating-Solar-Power-Industry-2023.pdf |title=Blue Book of China's Concentrating Solar Power Industry 2023|access-date=6 March 2024}}</ref> This makes CSP a [[Dispatchable generation|dispatchable]] form of solar. Dispatchable [[renewable energy]] is particularly valuable in places where there is already a high penetration of photovoltaics (PV), such as [[solar power in California|California]],<ref>{{cite web |url=http://www.solarpaces.org/chance-csp-california-outlaws-gas-fired-peaker-plants/ |title=New Chance for US CSP? California Outlaws Gas-Fired Peaker Plants|date=13 October 2017 |access-date=23 February 2018}}</ref> because demand for electric power peaks near sunset just as PV capacity ramps down (a phenomenon referred to as [[duck curve]]).<ref>{{cite web |last=Deign |first=Jason |title=Concentrated Solar Power Quietly Makes a Comeback |url=https://www.greentechmedia.com/articles/read/concentrated-solar-power-quietly-makes-a-comeback |website=GreenTechMedia.com |date=24 June 2019}}</ref>

CSP is often compared to [[Growth of photovoltaics|photovoltaic]] solar (PV) since they both use solar energy. While solar PV experienced huge growth during the 2010s due to falling prices,<ref>{{cite web |url=http://helioscsp.com/as-concentrated-solar-power-bids-fall-to-record-lows-prices-seen-diverging-between-different-regions/ |title=As Concentrated Solar Power bids fall to record lows, prices seen diverging between different regions|access-date=23 February 2018}}</ref><ref>{{cite web |url=http://www.kcet.org/news/redefine/rewire/solar/concentrating-solar/are-solar-power-towers-doomed-in-california.html |title=Are Solar Power Towers Doomed in California? |author=Chris Clarke |work=KCET|date=25 September 2015 }}</ref> solar CSP growth has been slow due to technical difficulties and high prices. In 2017, CSP represented less than 2% of worldwide installed capacity of solar electricity plants.<ref>{{cite web |url=https://www.ethz.ch/en/news-and-events/eth-news/news/2017/09/concentrating-solar-power.html |website=ETH Zurich |first1=Johan |last1=Lilliestam  |title=After the Desertec hype: is concentrating solar power still alive?|date=24 September 2017 |access-date= 24 September 2017}}</ref> However, CSP can more easily store energy during the night, making it more competitive with [[dispatchable generation|dispatchable generators]] and baseload plants.<ref>{{cite web|url=http://www.solarpaces.org/csp-competes-with-natural-gas-not-pv/ |first1=Susan |last1=Kraemer |website=SolarPACES |title=CSP Doesn't Compete With PV – it Competes with Gas|date=11 October 2017 |access-date=4 March 2018 |url-status=live |archive-url=https://web.archive.org/web/20180310042614/http://www.solarpaces.org/csp-competes-with-natural-gas-not-pv/ |archive-date= Mar 10, 2018 }}</ref><ref>{{cite web |url=https://cleantechnica.com/2019/06/04/concentrated-solar-power-costs-fell-46-from-2010-2018/ |website=CleanTechnica |date=June 4, 2019 |last1=smiti |title=Concentrated Solar Power Costs Fell 46% From 2010–2018|access-date=3 June 2019}}</ref><ref name="dub">{{cite web |url=http://helioscsp.com/uaes-push-on-concentrated-solar-power-should-open-eyes-across-world/ |first1=Robin |last1=Mills |website=HELIOSCSP |date=2017-09-25 |title=UAE's push on concentrated solar power should open eyes across world|access-date=29 October 2017 |url-status=dead |archive-url= https://web.archive.org/web/20170926235527/http://helioscsp.com/uaes-push-on-concentrated-solar-power-should-open-eyes-across-world/ |archive-date= Sep 26, 2017 }}</ref><ref>{{cite web |url=http://helioscsp.com/concentrated-solar-power-dropped-50-in-six-months/ |website=HELIOSCSP |date=30 October 2017 |first1=Susan |last1=Kraemer |title=Concentrated Solar Power Dropped 50% in Six Months|access-date=31 October 2017 |url-status=dead |archive-url= https://web.archive.org/web/20171107015833/http://helioscsp.com/concentrated-solar-power-dropped-50-in-six-months/ |archive-date= Nov 7, 2017 }}</ref>

The DEWA project in Dubai, under construction in 2019, held the world record for lowest CSP price in 2017 at US$73 per MWh<ref>{{Cite web|url=https://analysis.newenergyupdate.com/csp-today/acwa-power-scales-tower-trough-design-set-record-low-csp-price|title=ACWA Power scales up tower-trough design to set record-low CSP price|date=September 20, 2017|website=New Energy Update / CSP Today|access-date=November 29, 2019 |url-status=live |archive-url=https://web.archive.org/web/20191005092959/https://analysis.newenergyupdate.com/csp-today/acwa-power-scales-tower-trough-design-set-record-low-csp-price |archive-date= Oct 5, 2019 }}</ref> for its 700 MW combined trough and tower project: 600 MW of trough, 100 MW of tower with 15 hours of thermal energy storage daily. Base-load CSP tariff in the extremely dry [[Atacama region]] of [[Chile]] reached below $50/MWh in 2017 auctions.<ref name="chile">{{cite web |url=http://www.solarpaces.org/solarreserve-bids-csp-5-cents-chilean-auction/ |website=SolarPACES  |title=SolarReserve Bids CSP Under 5 Cents in Chilean Auction|date=29 October 2017 |access-date=29 October 2017}}</ref><ref name="Kraemer">{{cite web|url=https://cleantechnica.com/2017/03/13/solarreserve-bids-24-hour-solar-6-3-cents-chile/ |last1=susan |title=SolarReserve Bids 24-Hour Solar At 6.3 Cents In Chile|date=13 March 2017|publisher=CleanTechnica|access-date=14 March 2017}}</ref>

== History ==
[[File:1901 solar motor.jpg|thumb|upright|Solar steam engine for water pumping, near Los Angeles circa 1901]]

A legend has it that [[Archimedes]] used a "burning glass" to concentrate sunlight on the invading Roman fleet and repel them from [[Syracuse, Sicily#Greek period|Syracuse]]. In 1973 a Greek scientist, Dr. Ioannis Sakkas, curious about whether Archimedes could really have destroyed the Roman fleet in 212 BC, lined up nearly 60 Greek sailors, each holding an oblong mirror tipped to catch the sun's rays and direct them at a tar-covered plywood silhouette {{convert|160|ft|m|abbr=on|order=flip}} away. The ship caught fire after a few minutes; however, historians continue to doubt the Archimedes story.<ref>{{cite journal |author=Thomas W. Africa |jstor=4348211 |title=Archimedes through the Looking Glass |date=1975 |journal=The Classical World |volume=68 |issue=5 |pages=305–308 |doi=10.2307/4348211}}</ref>

In 1866, [[Auguste Mouchout]] used a parabolic trough to produce steam for the first solar steam engine. The first patent for a solar collector was obtained by the Italian Alessandro Battaglia in Genoa, Italy, in 1886. Over the following years, invеntors such as [[John Ericsson]] and [[Frank Shuman]] developed concentrating solar-powered dеvices for irrigation, refrigеration, and locomоtion. In 1913 Shuman finished a {{convert|55|hp|kW}} parabolic [[solar thermal energy]] station in Maadi, Egypt for irrigation.<ref>Ken Butti, John Perlin (1980) ''A Golden Thread: 2500 Years of Solar Architecture and Technology'', Cheshire Books, pp. 66–100, {{ISBN|0442240058}}.</ref><ref>{{cite web |first=CM |last=Meyer |url=http://eepublishers.co.za/article/from-troughs-to-triumph-segs-and-gas.html |title=From Troughs to Triumph: SEGS and Gas |website=EEPublishers.co.za |access-date=22 April 2013 |archive-url=https://web.archive.org/web/20110807122351/http://eepublishers.co.za/article/from-troughs-to-triumph-segs-and-gas.html |archive-date=7 August 2011 }}</ref><ref>Cutler J. Cleveland (23 August 2008). [http://www.eoearth.org/article/Shuman,_Frank Shuman, Frank]. Encyclopedia of Earth.</ref><ref>Paul Collins (Spring 2002) [http://www.cabinetmagazine.org/issues/6/beautifulpossibility.php The Beautiful Possibility]. Cabinet Magazine, Issue 6.</ref> The first solar-power system using a mirror dish was built by [[Robert H. Goddard|Dr. R.H. Goddard]], who was already well known for his research on liquid-fueled rockets and wrote an article in 1929 in which he asserted that all the previous obstacles had been addressed.<ref>[https://books.google.com/books?id=FSgDAAAAMBAJ&pg=PA22 "A New Invention To Harness The Sun"] ''Popular Science'', November 1929</ref>

Professor Giovanni Francia (1911–1980) designed and built the first concentrated-solar plant, which entered into operation in Sant'Ilario, near Genoa, Italy in 1968. This plant had the architecture of today's power tower plants, with a solar receiver in the center of a field of solar collectors. The plant was able to produce 1&nbsp;MW with superheated steam at 100 bar and 500&nbsp;°C.<ref>Ken Butti, John Perlin (1980) ''A Golden Thread: 2500 Years of Solar Architecture and Technology'', Cheshire Books, p. 68, {{ISBN|0442240058}}.</ref> The 10&nbsp;MW [[The Solar Project|Solar One]] power tower was developed in Southern California in 1981. [[The Solar Project#Solar One|Solar One]] was converted into [[The Solar Project#Solar Two|Solar Two]] in 1995, implementing a new design with a molten salt mixture (60% sodium nitrate, 40% potassium nitrate) as the receiver working fluid and as a storage medium. The molten salt approach proved effective, and Solar Two operated successfully until it was decommissioned in 1999.<ref>{{Cite web|url=http://large.stanford.edu/courses/2015/ph240/dodaro2/|title=Molten Salt Storage|website=large.stanford.edu|access-date=2019-03-31}}</ref> The parabolic-trough technology of the nearby [[Solar Energy Generating Systems]] (SEGS), begun in 1984, was more workable. The 354&nbsp;MW SEGS was the largest solar power plant in the world until 2014.

No commercial concentrated solar was constructed from 1990, when SEGS was completed, until 2006, when the [[Compact linear Fresnel reflector]] system at Liddell Power Station in Australia was built. Few other plants were built with this design, although the 5&nbsp;MW [[Kimberlina Solar Thermal Energy Plant]] opened in 2009.

In 2007, 75&nbsp;MW Nevada Solar One was built, a trough design and the first large plant since SEGS. Between 2010 and 2013, Spain built over 40 parabolic trough systems, size constrained at no more than 50&nbsp;MW by the support scheme. Where not bound in other countries, the manufacturers have adopted up to 200&nbsp;MW size for a single unit,<ref>{{cite web |url=https://www.solarpaces.org/power-china-has-begun-construction-of-the-worlds-only-200mw-tower-csp/ |title=Power China has begun construction of the world's only 200MW Tower CSP |date=22 March 2024 | website=www.solarpaces.org |url-status=live |archive-url=https://web.archive.org/web/20240322023607/https://www.solarpaces.org/power-china-has-begun-construction-of-the-worlds-only-200mw-tower-csp/ |archive-date=22 March 2024 |access-date=27 October 2024}}</ref> with a cost soft point around 125&nbsp;MW for a single unit.

Due to the success of Solar Two, a commercial power plant, called [[Gemasolar Thermosolar Plant|Solar Tres Power Tower]], was built in Spain in 2011, later renamed Gemasolar Thermosolar Plant. Gemasolar's results paved the way for further plants of its type. [[Ivanpah Solar Power Facility]] was constructed at the same time but without thermal storage, using natural gas to preheat water each morning.

Most concentrated solar power plants use the parabolic trough design, instead of the power tower or Fresnel systems. There have also been variations of parabolic trough systems like the [[Combined cycle#Integrated solar combined cycle (ISCC)|integrated solar combined cycle (ISCC)]] which combines troughs and conventional fossil fuel heat systems.

CSP was originally treated as a competitor to photovoltaics, and Ivanpah was built without energy storage, although Solar Two included several hours of thermal storage. By 2015, prices for photovoltaic plants had fallen and PV commercial power was selling for {{frac|1|3}} of contemporary CSP contracts.<ref>{{cite web|url=http://ww2.kqed.org/news/2015/12/15/nrg-ivanpah-faces-chance-of-default-PGE-contract|title=Ivanpah Solar Project Faces Risk of Default on PG&E Contracts|work=KQED News|archive-url=https://web.archive.org/web/20160325144752/http://ww2.kqed.org/news/2015/12/15/nrg-ivanpah-faces-chance-of-default-PGE-contract|archive-date=25 March 2016}}</ref><ref>{{Cite web|url=http://guntherportfolio.com/2013/04/esolar-sierra-suntower-a-history-of-concentrating-solar-power-underperformance/|title=eSolar Sierra SunTower: a History of Concentrating Solar Power Underperformance &#124; Gunther Portfolio|website=guntherportfolio.com|date=5 April 2013 }}</ref> However, increasingly, CSP was being bid with 3 to 12 hours of thermal energy storage, making CSP a dispatchable form of solar energy.<ref>{{Cite news|url=https://www.greentechmedia.com/articles/read/why-concentrating-solar-power-needs-storage-to-survive#gs.zD6uAiA|title=Why Concentrating Solar Power Needs Storage to Survive|access-date=21 November 2017}}</ref> As such, it is increasingly seen as competing with natural gas and PV with batteries for flexible, dispatchable power.

== Current technology ==
CSP is used to produce electricity (sometimes called solar thermoelectricity, usually generated through [[steam]]). Concentrated solar technology systems use [[mirror]]s or [[lens (optics)|lens]]es with [[Optical motion tracking|tracking]] systems to focus a large area of sunlight onto a small area. The concentrated light is then used as heat or as a heat source for a conventional [[power plant]] (solar thermoelectricity). The solar concentrators used in CSP systems can often also be used to provide industrial process heating or cooling, such as in [[solar air conditioning]].

Concentrating technologies exist in four optical types, namely [[parabolic trough]], [[dish Stirling|dish]], [[Compact Linear Fresnel Reflector|concentrating linear Fresnel reflector]], and [[solar power tower]].<ref name=tomkonrad>[http://tomkonrad.wordpress.com/2006/12/07/they-do-it-with-mirrors-concentrating-solar-power/ Types of solar thermal CSP plants]. Tomkonrad.wordpress.com. Retrieved on 22 April 2013.</ref> Parabolic trough and concentrating linear Fresnel reflectors are classified as linear focus collector types, while dish and solar tower are point focus types. Linear focus collectors achieve medium concentration factors (50 suns and over), and point focus collectors achieve high concentration factors (over 500 suns). Although simple, these solar concentrators are quite far from the theoretical maximum concentration.<ref name="IntroNio2e">{{cite book |first=Julio |last=Chaves |title=Introduction to Nonimaging Optics, Second Edition |url=https://books.google.com/books?id=e11ECgAAQBAJ |publisher=[[CRC Press]] |year=2015 |isbn=978-1482206739}}</ref><ref name="NIO">Roland Winston, Juan C. Miñano, Pablo G. Benitez (2004) ''Nonimaging Optics'', Academic Press, {{ISBN|978-0127597515}}.</ref> For example, the parabolic-trough concentration gives about {{frac|1|3}} of the theoretical maximum for the design [[Acceptance angle (solar concentrator)|acceptance angle]], that is, for the same overall tolerances for the system. Approaching the theoretical maximum may be achieved by using more elaborate concentrators based on [[nonimaging optics]].<ref name="IntroNio2e"/><ref name="NIO"/><ref>{{cite book |last=Norton |first=Brian |title=Harnessing Solar Heat |date=2013 |publisher=Springer |isbn=978-94-007-7275-5}}</ref>

Different types of concentrators produce different peak temperatures and correspondingly varying thermodynamic efficiencies due to differences in the way that they track the sun and focus light. New innovations in CSP technology are leading systems to become more and more cost-effective.<ref>[http://www.popularmechanics.com/science/research/4288743.html?page=1 New innovations in solar thermal] {{Webarchive|url=https://web.archive.org/web/20090421165638/http://www.popularmechanics.com/science/research/4288743.html?page=1 |date=21 April 2009 }}. Popularmechanics.com (1 November 2008). Retrieved on 22 April 2013.</ref><ref name="Yogender Pal Chandra">{{cite journal|last1=Chandra|first1=Yogender Pal|title=Numerical optimization and convective thermal loss analysis of improved solar parabolic trough collector receiver system with one sided thermal insulation|journal=Solar Energy |date=17 April 2017|volume=148|pages=36–48|doi=10.1016/j.solener.2017.02.051|bibcode=2017SoEn..148...36C}}</ref>

In 2023, Australia’s national science agency [[CSIRO]] tested a CSP arrangement in which tiny ceramic particles fall through the beam of concentrated solar energy, the ceramic particles capable of storing a greater amount of heat than molten salt, while not requiring a container that would diminish heat transfer.<ref name=Freethink_20231112>{{cite news |last1=Houser |first1=Kristin |title=Aussie scientists hit milestone in concentrated solar power They heated ceramic particles to a blistering 1450 F by dropping them through a beam of concentrated sunlight. |url=https://www.freethink.com/energy/concentrated-solar-power-ceramic-particles |work=Freethink |date=12 November 2023 |archive-url=https://web.archive.org/web/20231115055619/https://www.freethink.com/energy/concentrated-solar-power-ceramic-particles |archive-date=15 November 2023 |url-status=live }}</ref>

=== Parabolic trough ===
{{Main|Parabolic trough}}
[[File:Parabolic trough at Harper Lake in California.jpg|thumb|right|Parabolic trough at a plant near Harper Lake, California]]
[[File:Linear Parabolic Reflector Diagram (Concentrated Solar Power).svg|thumb|Diagram of linear parabolic reflector concentrating sun rays to heat working fluid]]
A parabolic trough consists of a linear parabolic reflector that concentrates light onto a receiver positioned along the reflector's focal line. The receiver is a tube positioned at the longitudinal focal line of the parabolic mirror and filled with a working fluid. The reflector follows the sun during the daylight hours by tracking along a single axis. A [[working fluid]] (e.g. [[molten salt]]<ref>{{cite journal |last1=Vignarooban |first1=K. |last2=Xinhai |first2=Xu |year=2015 |title=Heat transfer fluids for concentrating solar power systems – A review |journal=Applied Energy |volume= 146|pages= 383–396|doi=10.1016/j.apenergy.2015.01.125|bibcode=2015ApEn..146..383V }}</ref>) is heated to {{convert|150|–|350|C|F}} as it flows through the receiver and is then used as a heat source for a power generation system.<ref name="Martin 2005">{{cite book |author1=Christopher L. Martin |author2=D. Yogi Goswami |title=Solar energy pocket reference |url=https://books.google.com/books?id=tIFUAAAAMAAJ |date=2005 |publisher=Earthscan |isbn=978-1-84407-306-1 |page=45}}</ref> Trough systems are the most developed CSP technology. The [[Solar Energy Generating Systems]] (SEGS) plants in California, some of the longest-running in the world until their 2021 closure;<ref name=":1">{{Cite web |title=Solar thermal power plants - U.S. Energy Information Administration (EIA) |url=https://www.eia.gov/energyexplained/solar/solar-thermal-power-plants.php |access-date=2024-10-22 |website=www.eia.gov}}</ref> Acciona's [[Nevada Solar One]] near [[Boulder City, Nevada]];<ref name=":1" /> and [[Andasol]], Europe's first commercial parabolic trough plant are representative,<ref>{{Cite news |title=Earthprints: Andasol solar power station |url=https://widerimage.reuters.com/story/earthprints-andasol-solar-power-station |access-date=2024-10-22 |work=Reuters |language=en}}</ref> along with [[Plataforma Solar de Almería]]'s SSPS-DCS test facilities in [[Solar power in Spain|Spain]].<ref name="Plataforma">{{cite web |title=Linear-focusing Concentrator Facilities: DCS, DISS, EUROTROUGH and LS3 |publisher=Plataforma Solar de Almería |url=http://www.psa.es/webeng/instalaciones/parabolicos.html |access-date=29 September 2007 |archive-url=https://web.archive.org/web/20070928042703/http://www.psa.es/webeng/instalaciones/parabolicos.html |archive-date=28 September 2007}}</ref>

==== Enclosed trough ====
The design encapsulates the solar thermal system within a greenhouse-like glasshouse. The glasshouse creates a protected environment to withstand the elements that can negatively impact reliability and efficiency of the solar thermal system.<ref name="deloitte">Deloitte Touche Tohmatsu Ltd, [http://www.deloitte.com/energypredictions2012 "Energy & Resources Predictions 2012"] {{Webarchive|url=https://web.archive.org/web/20130106174132/http://www.deloitte.com/energypredictions2012 |date=6 January 2013 }}, 2 November 2011</ref> Lightweight curved solar-reflecting mirrors are suspended from the ceiling of the glasshouse by wires. A [[Solar tracker|single-axis tracking system]] positions the mirrors to retrieve the optimal amount of sunlight. The mirrors concentrate the sunlight and focus it on a network of stationary steel pipes, also suspended from the glasshouse structure.<ref>Helman, [https://www.forbes.com/forbes/2011/0425/features-glasspoint-greenhouses-green-energy-oil-from-sun.html "Oil from the sun"], "Forbes", 25 April 2011</ref> Water is carried throughout the length of the pipe, which is boiled to generate steam when intense solar radiation is applied. Sheltering the mirrors from the wind allows them to achieve higher temperature rates and prevents dust from building up on the mirrors.<ref name="deloitte"/>

[[GlassPoint Solar]], the company that created the Enclosed Trough design, states its technology can produce heat for [[Enhanced Oil Recovery]] (EOR) for about $5 per {{convert|1000000|BTU|kWh|abbr=on|order=flip}} in sunny regions, compared to between $10 and $12 for other conventional solar thermal technologies.<ref name="ehren chevron">Goossens, Ehren, [https://www.bloomberg.com/news/2011-10-03/chevron-using-solar-thermal-steam-at-enhanced-oil-recovery-plant.html "Chevron Uses Solar-Thermal Steam to Extract Oil in California"], "Bloomberg", 3 October 2011</ref>

=== Solar power tower ===
{{Main|Solar power tower}}
[[File:Brigthsource Tower Ashalim.jpg|thumb|upright|[[Ashalim Power Station]], Israel, on its completion the tallest solar tower in the world. It concentrates light from over 50,000 heliostats.]] 
[[File:PS10 solar power tower.jpg|thumb|The [[PS10 solar power plant]] in [[Andalusia]], Spain concentrates sunlight from a field of [[heliostat]]s onto a central solar power tower.]]

A solar power tower consists of an array of dual-axis tracking reflectors ([[heliostat]]s) that concentrate sunlight on a central receiver atop a tower; the receiver contains a heat-transfer fluid, which can consist of water-steam or [[molten salt]]. Optically a solar power tower is the same as a circular Fresnel reflector. The working fluid in the receiver is heated to 500–1000&nbsp;°C ({{convert|773|-|1273|K|F|disp=or}}) and then used as a heat source for a power generation or energy storage system.<ref name="Martin 2005"/> An advantage of the solar tower is the reflectors can be adjusted instead of the whole tower. Power-tower development is less advanced than trough systems, but they offer higher efficiency and better energy storage capability. Beam down tower application is also feasible with heliostats to heat the working fluid.<ref>{{Cite web |url=http://helioscsp.com/three-solar-modules-of-worlds-first-commercial-beam-down-tower-concentrated-solar-power-project-to-be-connected-to-grid/ |title=Three solar modules of world's first commercial beam-down tower Concentrated Solar Power project to be connected to grid |access-date=18 August 2019 }}</ref> CSP with dual towers are also used to enhance the conversion efficiency by nearly 24%.<ref>{{Cite web |url=https://www.world-energy.org/article/43580.html |title=World's First Dual-Tower Concentrated Solar Power Plant Boosts Efficiency by 24% |access-date=22 July 2022}}</ref>

The [[Solar Two]] in [[Daggett, California|Daggett]], California and the CESA-1 in [[Plataforma Solar de Almeria]] Almeria, Spain, are the most representative demonstration plants. The [[PS10 solar power tower|Planta Solar 10]] (PS10) in [[Sanlucar la Mayor]], Spain, is the first commercial utility-scale solar power tower in the world. The 377&nbsp;MW [[Ivanpah Solar Power Facility]], located in the [[Mojave Desert]], was the largest CSP facility in the world, and uses three power towers.<ref>{{cite web|url=http://www.brightsourceenergy.com/ivanpah-solar-project|title=Ivanpah - World's Largest Solar Plant in California Desert|website=BrightSourceEnergy.com}}</ref> Ivanpah generated only 0.652&nbsp;TWh (63%) of its energy from solar means, and the other 0.388&nbsp;TWh (37%) was generated by burning [[natural gas]].<ref>{{cite web|url=http://www.eia.gov/electricity/data/browser/#/plant/57073|title=Electricity Data Browser|website=EIA.gov}}</ref><ref>{{cite web|url=http://www.eia.gov/electricity/data/browser/#/plant/57074|title=Electricity Data Browser|website=EIA.gov}}</ref><ref>{{cite web|url=http://www.eia.gov/electricity/data/browser/#/plant/57075|title=Electricity Data Browser|website=EIA.gov}}</ref>

[[Supercritical carbon dioxide]] can be used instead of steam as heat-transfer fluid for increased [[Electricity generation|electricity production]] efficiency. However, because of the high temperatures in [[arid]] areas where solar power is usually located, it is impossible to cool down carbon dioxide below its [[Critical point (thermodynamics)|critical temperature]] in the [[compressor]] inlet. Therefore, [[supercritical carbon dioxide blend]]s with higher critical temperatures are currently in development.

=== Fresnel reflectors ===
{{Main|Compact linear Fresnel reflector}}

Fresnel reflectors are made of many thin, flat mirror strips to concentrate sunlight onto tubes through which working fluid is pumped. Flat mirrors allow more reflective surface in the same amount of space than a parabolic reflector, thus capturing more of the available sunlight, and they are much cheaper than parabolic reflectors.<ref>{{cite journal|title=Land-Use competitiveness of photovoltaic and concentrated solar power technologies near the Tropic of Cancer |date=September 2022|doi=10.1016/j.solener.2022.07.051 |last1=Marzouk |first1=Osama A. |journal=Solar Energy |volume=243 |pages=103–119 |bibcode=2022SoEn..243..103M |s2cid=251357374 |doi-access=free }}</ref> Fresnel reflectors can be used in various size CSPs.<ref>[http://www.physics.usyd.edu.au/app/research/solar/clfr.html Compact CLFR]. Physics.usyd.edu.au (12 June 2002). Retrieved on 22 April 2013.</ref><ref>[https://web.archive.org/web/20110721150750/http://www.ese.iitb.ac.in/activities/solarpower/ausra.pdf Ausra's Compact Linear Fresnel Reflector (CLFR) and Lower Temperature Approach]. ese.iitb.ac.in</ref>

Fresnel reflectors are sometimes regarded as a technology with a worse output than other methods. The cost efficiency of this model is what causes some to use this instead of others with higher output ratings. Some new models of Fresnel reflectors with Ray Tracing capabilities have begun to be tested and have initially proved to yield higher output than the standard version.<ref>{{cite journal |last1=Abbas |first1=R. |last2=Muñoz-Antón |first2=J. |last3=Valdés |first3=M. |last4=Martínez-Val |first4=J.M. |title=High concentration linear Fresnel reflectors |journal=Energy Conversion and Management |date=August 2013 |volume=72 |pages=60–68 |doi=10.1016/j.enconman.2013.01.039|bibcode=2013ECM....72...60A }}</ref>

=== Dish Stirling ===
{{see also|Solar thermal energy#Dish designs}}
[[File:SolarStirlingEngine.jpg|thumb|[[Solar thermal energy#Dish designs|A dish Stirling]] ]]

A dish Stirling or dish engine system consists of a stand-alone [[parabolic reflector]] that concentrates light onto a receiver positioned at the reflector's focal point. The reflector tracks the Sun along two axes. The working fluid in the receiver is heated to {{convert|250|–|700|C|F}} and then used by a [[Stirling engine]] to generate power.<ref name="Martin 2005"/> Parabolic-dish systems provide high solar-to-electric efficiency (between 31% and 32%), and their modular nature provides scalability. The [[Stirling Energy Systems]] (SES), [[United Sun Systems International|United Sun Systems]] (USS) and [[Science Applications International Corporation|Science Applications International Corporation (SAIC)]] dishes at [[University of Nevada, Las Vegas|UNLV]], and [[Australian National University]]'s [[The Big Dish (solar thermal)|Big Dish]] in [[Canberra]], Australia are representative of this technology. A world record for solar to electric efficiency was set at 31.25% by SES dishes at the [[National Solar Thermal Test Facility]] (NSTTF) in New Mexico on 31 January 2008, a cold, bright day.<ref>[https://newsreleases.sandia.gov/releases/2008/solargrid.html Sandia, Stirling Energy Systems set new world record for solar-to-grid conversion efficiency], Sandia, Feb. 12, 2008. Retrieved on 21 October 2021.{{Webarchive|url=https://web.archive.org/web/20130219193847/https://share.sandia.gov/news/resources/releases/2008/solargrid.html |date=19 February 2013 }}.</ref> According to its developer, Ripasso Energy, a Swedish firm, in 2015 its dish Stirling system tested in the [[Kalahari Desert]] in South Africa showed 34% efficiency.<ref name="Guardian51315">{{cite news |first=Jeffrey |last=Barbee |title=Could this be the world's most efficient solar electricity system? |url=https://www.theguardian.com/environment/2015/may/13/could-this-be-the-worlds-most-efficient-solar-electricity-system |access-date=21 April 2017 |work=The Guardian |date=13 May 2015 |quote=34% of the sun's energy hitting the mirrors is converted directly to grid-available electric power}}</ref> The SES installation in Maricopa, Phoenix, was the largest Stirling Dish power installation in the world until it was sold to [[United Sun Systems International|United Sun Systems]]. Subsequently, larger parts of the installation have been moved to China to satisfy part of the large energy demand.

== CSP with thermal energy storage ==
{{See also|Thermal energy storage|Solar thermal energy}}

In a CSP plant that includes storage, the solar energy is first used to heat molten salt or synthetic oil, which is stored providing thermal/heat energy at high temperature in insulated tanks.<ref>{{Cite news|url=http://www.solarpaces.org/how-csp-thermal-energy-storage-works/|title=How CSP's Thermal Energy Storage Works - SolarPACES|date=10 September 2017|work=SolarPACES|access-date=21 November 2017}}</ref><ref>{{cite web|url=http://www.solarreserve.com/en/technology/molten-salt-energy-storage|title=Molten salt energy storage|access-date=22 August 2017|archive-url=https://web.archive.org/web/20170829132011/http://www.solarreserve.com/en/technology/molten-salt-energy-storage|archive-date=29 August 2017}}</ref> Later the hot molten salt (or oil) is used in a steam generator to produce steam to generate electricity by steam [[turbo generator]] as required.<ref>{{cite web |url=http://www.powermag.com/the-latest-in-thermal-energy-storage/|title=The Latest in Thermal Energy Storage |date=July 2017 |access-date= 22 August 2017}}</ref> Thus solar energy which is available in daylight only is used to generate electricity round the clock on demand as a [[load following power plant]] or solar peaker plant.<ref>{{cite web |url=https://www.greentechmedia.com/articles/read/is-csp-viable-without-storage#gs.9UN2YLg|title=Concentrating Solar Power Isn't Viable Without Storage, Say Experts |access-date= 29 August 2017}}</ref><ref>{{cite web |url=http://www.solarpaces.org/study-solar-peaker-compete-with-gas/|title=How Solar Peaker Plants Could Replace Gas Peakers |date=19 October 2017 |access-date= 2 April 2018}}</ref> The thermal storage capacity is indicated in hours of power generation at [[nameplate capacity]]. Unlike [[photovoltaics|solar PV]] or CSP without storage, the power generation from solar thermal storage plants is [[ancillary services (electric power)|dispatchable and self-sustainable]], similar to coal/[[gas-fired power plant]]s, but without the pollution.<ref>{{cite web |url=http://reneweconomy.com.au/aurora-what-you-should-know-about-port-augustas-solar-power-tower-86715/|title=Aurora: What you should know about Port Augusta's solar power-tower |date=21 August 2017 |access-date= 22 August 2017}}</ref> CSP with thermal energy storage plants can also be used as [[cogeneration]] plants to supply both electricity and process steam round the clock. As of December 2018, CSP with thermal energy storage plants' generation costs have ranged between 5 c&nbsp;€&nbsp;/ kWh and 7 c&nbsp;€&nbsp;/ kWh, depending on good to medium solar radiation received at a location.<ref>{{cite web |url=http://helioscsp.com/2018-the-year-in-which-the-concentrated-solar-power-returned-to-shine/|title=2018, the year in which the Concentrated Solar Power returned to shine |access-date= 18 December 2018}}</ref> Unlike solar PV plants, CSP with thermal energy storage can also be used economically around the clock to produce process steam, replacing polluting [[fossil fuels]]. CSP plants can also be integrated with solar PV for better synergy.<ref>{{Cite news |url=https://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151_read-34003/#/gallery/28711|title=Controllable solar power – competitively priced for the first time in North Africa |access-date= 7 June 2019}}</ref><ref>{{Cite news |url=https://www.solarpaces.org/morocco-breaks-new-record-with-800-mw-midelt-1-csp-pv-at-7-cents/|title=Morocco Breaks New Record with 800 MW Midelt 1 CSP-PV at 7 Cents |access-date= 7 June 2019}}</ref><ref>{{Cite news |url=https://www.solarpaces.org/morocco-pioneers-pv-with-thermal-storage-at-800-mw-midelt-csp-project/|title=Morocco Pioneers PV with Thermal Storage at 800 MW Midelt CSP Project |access-date= 25 April 2020}}</ref>

CSP with thermal storage systems are also available using [[Brayton cycle]] generators with air instead of steam for generating electricity and/or steam round the clock. These CSP plants are equipped with [[gas turbine|gas turbines]] to generate electricity.<ref name="helioscsp.com">{{cite web |url=http://helioscsp.com/247solar-and-masen-ink-agreement-for-first-operational-next-generation-concentrated-solar-power-plant/|title=247Solar and Masen Ink Agreement for First Operational Next Generation Concentrated Solar Power Plant|access-date= 31 August 2019}}</ref> These are also small in capacity (<0.4 MW), with flexibility to install in few acres' area.<ref name="helioscsp.com"/> Waste heat from the power plant can also be used for process steam generation and [[HVAC]] needs.<ref>{{Cite web |url=http://helioscsp.com/247solar-modular-scalable-concentrated-solar-power-tech-to-be-marketed-to-mining-by-rost/ |archive-url=https://web.archive.org/web/20191028184401/http://helioscsp.com/247solar-modular-scalable-concentrated-solar-power-tech-to-be-marketed-to-mining-by-rost/ |url-status=dead |archive-date=28 October 2019 |title=247 solar modular & scalable concentrated solar power tech to be marketed to mining by Rost|access-date=31 October 2019}}</ref> In case land availability is not a limitation, any number of these modules can be installed, up to 1000 MW with [[RAMS]] and cost advantages since the per MW costs of these units are lower than those of larger size solar thermal stations.<ref>{{Cite web |url=http://helioscsp.com/capex-of-modular-concentrated-solar-power-plants-could-halve-if-1-gw-deployed/ |title=Capex of modular Concentrated Solar Power plants could halve if 1 GW deployed|access-date=31 October 2019 }}</ref>

Centralized district heating round the clock is also feasible with [[Solar thermal energy|concentrated solar thermal]] storage plants.<ref>{{Cite web |url=http://helioscsp.com/tibets-first-solar-district-heating-plant/ |title=Tibet's first solar district heating plant|access-date=20 December 2019 }}</ref>

== Deployment around the world ==
{{Main|List of solar thermal power stations|Solar power by country}}

<!-- bar-chart of worldwide CSP capacity -->
{{Image frame
| width = 260
| align=left
| pos=bottom
| content=<div style="margin:15px 0 -45px -60px; font-size:80%;">{{ #invoke:Chart | bar-chart
  | width = 320
  | height = 350
  | group 1 = 14 : 74 : 74 : 74 : 74 : 274 : 354 : 354: 354: 354: 354: 354: 354: 354: 354: 354: 354: 354: 354: 354: 354: 354 : 355 : 429 : 484 : 663 : 969 : 1598 : 2553 : 3425 : 4335 : 4705 : 4815 : 4915 : 5465 : 6451
  | colors = maroon
  | group names =
  | units suffix = _MW
  | x legends = 1984 : : : : : : 1990: : : : : 1995 : : : : : 2000 : : : : : 2005 : : : : : 2010 : : : : : 2015 : : : : 
  }}</div>
| caption = '''Worldwide CSP capacity since 1984 in MW<sub>p</sub>'''
}}

{| class="wikitable sortable floatright" style="text-align: right;" 
|+ National CSP capacities in 2023 (MW<sub>p</sub>)
|-
! Country !! Total !! Added
|-
| align=left| [[Spain]] || 2,304 || 0
|-
| align=left| [[United States]] || 1,480 || 0
|-
| align=left| [[South Africa]] || 500 || 0
|-
| align=left| [[Morocco]] || 540 || 0
|-
| align=left| [[India]] || 343 || 0
|-
| align=left| [[China]] || 570 || 0 
|-
| align=left| [[United Arab Emirates]] || 600 || 300
|-
| align=left| [[Saudi Arabia]] || 50 || 0
|-
| align=left| [[Algeria]] || 25 || 0
|-
| align=left| [[Egypt]] || 20 || 0
|-
| align=left| [[Italy]] || 13 || 0
|-
| align=left| [[Australia]] || 5 || 0
|-
| align=left| [[Thailand]] || 5 || 0
|-
| colspan=3 style="font-size: 0.85em; padding: 6px 0 4px 2px; text-align:left;" | ''Source'': [[REN21]] Global Status Report, 2017 and 2018<ref name=ire/><ref name="ren21-gsr-2017">[http://www.ren21.net/wp-content/uploads/2017/06/170607_GSR_2017_Full_Report.pdf Renewables Global Status Report], REN21, 2017</ref><ref name=REN2018>[http://www.ren21.net/gsr-2018/chapters/chapter_03/chapter_03/#sub_6 Renewables 2017: Global Status Report], REN21, 2018</ref><ref name="HeliosCSP">{{cite web |title=Concentrated Solar Power increasing cumulative global capacity more than 11% to just under 5.5 GW in 2018 |url=http://helioscsp.com/concentrated-solar-power-increasing-cumulative-global-capacity-more-than-11-to-just-under-5-5-gw-in-2018/ |access-date=18 June 2019}}</ref>
|}

An early plant operated in Sicily at [[Adrano]]. The US deployment of CSP plants started by 1984 with the [[Solar Energy Generating Systems|SEGS]] plants. The last SEGS plant was completed in 1990. From 1991 to 2005, no CSP plants were built anywhere in the world. Global installed CSP-capacity increased nearly tenfold between 2004 and 2013 and grew at an average of 50 percent per year during the last five of those years, as the number of countries with installed CSP was growing.<ref name="ren21-gsr-2014" />{{rp|51}} In 2013, worldwide installed capacity increased by 36% or nearly 0.9 [[gigawatt]] (GW) to more than 3.4&nbsp;GW. The record for capacity installed was reached in 2014, corresponding to 925 MW; however, it was followed by a decline caused by policy changes, the global financial crisis, and the rapid decrease in price of the photovoltaic cells. Nevertheless, total capacity reached 6800 MW in 2021.<ref name="chinCSP">{{cite web |title=Blue Book of China's Concentrating Solar Power Industry, 2021 |url=https://www.solarpaces.org/wp-content/uploads/Blue-Book-on-Chinas-CSP-Industry-2021.pdf |access-date=16 June 2022}}</ref>

[[Solar power in Spain|Spain]] accounted for almost one third of the world's capacity, at 2,300&nbsp;MW, despite no new capacity entering commercial operation in the country since 2013.<ref name="HeliosCSP" />
The United States follows with 1,740&nbsp;MW. Interest is also notable in North Africa and the Middle East, as well as China and India. There is a notable trend towards developing countries and regions with high solar radiation with several large plants under construction in 2017.

{| class="wikitable" style="text-align: right;"
|+ Worldwide Concentrated Solar Power (MW<sub>p</sub>)
|-
! Year || 1984 || 1985 || 1989 || 1990 || 1991-2005 || 2006 || 2007 || 2008 || 2009 || 2010 || 2011 || 2012 || 2013 || 2014 || 2015 || 2016 || 2017 || 2018|| 2019 || 2020 ||2021||2022||2023
|-
| style="text-align:left; padding-left:8px;"| Installed || 14 || 60 || 200 || 80 || 0 || 1 || 74 || 55 || 179 || 307 || 629 || 803 || 872 || 925 || 420 || 266 || 101 || 740 || 566 ||38 || -39||199||300
|-
| style="text-align:left; padding-left:8px;"| Cumulative || 14 || 74 || 274 || 354 || 354 || 355 || 429 || 484 || 663 || 969 || 1,598 || 2,553 || 3,425 || 4,335 || 4,705 || 4,971 || 5,072|| 5,812 || 6,378||6,416 || 6,377||6,576||6,876<ref name=ire>{{Cite web|url=https://mc-cd8320d4-36a1-40ac-83cc-3389-cdn-endpoint.azureedge.net/-/media/Files/IRENA/Agency/Publication/2024/Mar/IRENA_RE_Capacity_Statistics_2024.pdf?rev=50a4c39fd14c4274b246cd51150a0aa1|title=Renewable Energy Capacity Statistics 2024, Irena|access-date=30 March 2024}}</ref>
|-
| colspan="22" style="background:#f2f2f2; font-size:0.85em; padding:6px 0 4px 4px; text-align:left;"| ''Sources'': [[REN21]]<ref name="ren21-gsr-2017" /><ref name="ren21-gsr-2016">{{cite book|url= http://www.ren21.net/wp-content/uploads/2016/10/REN21_GSR2016_FullReport_en_11.pdf |title=Renewables 2016: Global Status Report|author=((REN21))|date=2016 |publisher=REN21 Secretariat, UNEP |isbn=978-3-9818107-0-7 }}</ref>{{rp|146}}<ref name="ren21-gsr-2014">{{cite book |url=http://www.ren21.net/Portals/0/documents/Resources/GSR/2014/GSR2014_full%20report_low%20res.pdf |title=Renewables 2014: Global Status Report |author=((REN21)) |archive-url=https://web.archive.org/web/20140915214208/http://www.ren21.net/Portals/0/documents/Resources/GSR/2014/GSR2014_full%20report_low%20res.pdf |archive-date=15 September 2014 |isbn=978-3-9815934-2-6 |date=2014 |access-date=14 September 2014 }}</ref> {{rp|51}}<ref name=REN2018/> {{·}}CSP-world.com<ref>{{cite web |url=http://www.csp-world.com/resources/4-csp-facts-figures |title=CSP Facts & Figures |publisher=csp-world.com |date=June 2012 |access-date=22 April 2013 |archive-url=https://web.archive.org/web/20130429051148/http://www.csp-world.com/resources/4-csp-facts-figures |archive-date=29 April 2013 }}</ref>{{·}}[[International Renewable Energy Agency|IRENA]]<ref>{{cite web |url=http://www.irena.org/DocumentDownloads/Publications/RE_Technologies_Cost_Analysis-CSP.pdf |title=Concentrating Solar Power |publisher=International Renewable Energy Agency |page=11 |date=June 2012 |access-date=9 September 2012 |archive-date=22 November 2012 |archive-url=https://web.archive.org/web/20121122074056/http://www.irena.org/DocumentDownloads/Publications/RE_Technologies_Cost_Analysis-CSP.pdf }}</ref>{{·}} HeliosCSP<ref name="HeliosCSP" />
|}The global market was initially dominated by parabolic-trough plants, which accounted for 90% of CSP plants at one point.<ref name="saw2011">{{cite web |last1=Sawin |first1=Janet L. |last2=Martinot |first2=Eric |name-list-style=amp |date=29 September 2011 |title=Renewables Bounced Back in 2010, Finds REN21 Global Report |url=http://www.renewableenergyworld.com/rea/news/article/2011/09/renewables-bounced-back-in-2010-finds-ren21-global-report |archive-url=https://web.archive.org/web/20111102183605/http://www.renewableenergyworld.com/rea/news/article/2011/09/renewables-bounced-back-in-2010-finds-ren21-global-report |archive-date=2 November 2011 |work=Renewable Energy World}}</ref> 
Since about 2010, central power tower CSP has been favored in new plants due to its higher temperature operation – up to {{Convert|565|C|F|abbr=}} vs. trough's maximum of {{Convert|400|C||abbr=}} – which promises greater efficiency.

Among the [[List of solar thermal power stations|larger CSP projects]] are the [[Ivanpah Solar Power Facility]] (392&nbsp;MW) in the United States, which uses [[solar power tower]] technology without thermal energy storage, and the [[Ouarzazate Solar Power Station]] in Morocco,<ref>Louis Boisgibault, Fahad Al Kabbani (2020): [http://www.iste.co.uk/book.php?id=1591 ''Energy Transition in Metropolises, Rural Areas and Deserts'']. [[Wiley - ISTE]]. (Energy series) {{ISBN|9781786304995}}.</ref> which combines trough and tower technologies for a total of 510 MW with several hours of energy storage.

== Cost ==
On purely generation cost, bulk power from CSP today is much more expensive than solar PV or Wind power, however, PV and Wind power are [[Variable renewable energy|intermittent sources]]. Comparing cost on the electricity grid, gives a different conclusion. Developers are hoping that CSP with energy storage can be a cheaper alternative to PV with [[Battery energy storage system|BESS]]. Research found that PV with BESS is competitive for short storage durations, while CSP with TES gains economic advantages for long storage periods. Tipping point lies at 2–10 hours depending on cost of the composing blocks: CSP, PV, TES and BESS.<ref>{{cite web |url=https://www.rifs-potsdam.de/en/output/publications/2021/making-sun-shine-night-comparing-cost-dispatchable-concentrating-solar |title=Making the sun shine at night: comparing the cost of dispatchable concentrating solar power and photovoltaics with storage |date=2021 | publisher=[[Helmholtz Centre for Environmental Research]] |url-status=live |archive-url=https://web.archive.org/web/20240616045746/https://www.rifs-potsdam.de/en/output/publications/2021/making-sun-shine-night-comparing-cost-dispatchable-concentrating-solar |archive-date=16 June 2024 |access-date=28 October 2024}}</ref>
As early as 2011, the rapid decline of the price of [[photovoltaic system]]s led to projections that CSP (without TES) would no longer be economically viable.<ref name="googone">[http://www.evwind.es/noticias.php?id_not=14860 Google cans concentrated solar power project] {{Webarchive|url=https://web.archive.org/web/20120615142019/http://www.evwind.es/noticias.php?id_not=14860|date=2012-06-15}} ''Reve'', 24 Nov 2011. Accessed: 25 Nov 2011.</ref> As of 2020, the least expensive utility-scale concentrated solar power stations in the United States and worldwide were five times more expensive than utility-scale [[photovoltaic power station]]s, with a projected minimum price of 7 cents per kilowatt-hour for the most advanced CSP stations (with TES) against record lows of 1.32 cents per kWh<ref>{{cite news |last1=Shahan |first1=Zachary |date=30 August 2020 |title=New Record-Low Solar Price Bid — 1.3¢/kWh |url=https://cleantechnica.com/2020/08/30/new-record-low-solar-price-bid-1-3%C2%A2-kwh/ |access-date=8 January 2021 |publisher=CleanTechnica}}</ref> for utility-scale PV (without BESS).<ref>{{citation |title=NERL Annual Technology Baseline |year=2020 |access-date=23 April 2021 |archive-url=https://web.archive.org/web/20210421212708/https://atb.nrel.gov/electricity/2020/index.php?t=sc |archive-date=21 April 2021 |url-status=dead |chapter=Concentrating Solar Power |chapter-url=https://atb.nrel.gov/electricity/2020/index.php?t=sc}}</ref> This five-fold price difference has been maintained since 2018.<ref>{{citation |title=NERL Annual Technology Baseline |year=2018 |access-date=23 April 2021 |archive-url=https://web.archive.org/web/20210423082515/https://atb.nrel.gov/electricity/2018/index.html?t=sc |archive-date=23 April 2021 |url-status=dead |chapter=Concentrating Solar Power |chapter-url=https://atb.nrel.gov/electricity/2018/index.html?t=sc}}</ref> Some PV-CSP plants in China have sought to operate profitably on the regional coal tariff of 5 US cents per kWh in 2021.<ref name="chintar">{{cite web |title=Three Gorges Seeks EPC Bids for 200 MW of Concentrated Solar Power Under 5 cents/kWh |url=https://helioscsp.com/three-gorges-seeks-epc-bids-for-200-mw-of-concentrated-solar-power-under-5-cents-kwh/ |access-date=15 June 2022}}</ref>

Even though overall deployment of CSP remains limited in the early 2020s, the levelized cost of power from commercial scale plants has decreased significantly since the 2010s. With a learning rate estimated at around 20% cost reduction of every doubling in capacity,<ref>{{cite journal |author=Johan Lilliestam |display-authors=etal |year=2017 |title=Empirically observed learning rates for concentrating solar power and their responses to regime change |journal=Nature Energy |volume=2 |page=17094 |bibcode=2017NatEn...217094L |doi=10.1038/nenergy.2017.94 |s2cid=256727261 |number=17094}}</ref> the costs were approaching the upper end of the fossil fuel cost range at the beginning of the 2020s, driven by support schemes in several countries, including Spain, the US, Morocco, South Africa, China, and the UAE:

[[File:LCOE of Concentrating Solar Power from 2006-2019.jpg|LCOE of Concentrating Solar Power from 2006 to 2019|center|500px]]

CSP deployment has slowed down considerably in [[OECD]] countries, as most of the above-mentioned markets have cancelled their support, but CSP is one of the few renewable electricity technologies that can generate fully dispatchable or even fully baseload power at very large scale. Therefore, it may have an important role to play in the decarbonization of power grids as a dispatchable electricity source to balance the intermittent renewables, such as wind power and PV.<ref>{{cite journal |author=Johan Lilliestam |display-authors=etal |year=2020 |title=The near- to mid-term outlook for concentrating solar power: mostly cloudy, chance of sun |journal=Energy Sources, Part B |volume=16 |pages=23–41 |doi=10.1080/15567249.2020.1773580 |doi-access=free|url=https://zenodo.org/records/5519991/files/15567249.2020.pdf }}</ref> CSP in combination with [[Thermal Energy Storage]] (TES) is expected by some to become cheaper than PV with lithium batteries for storage durations above 4 hours per day,<ref>{{cite journal |last=Schöniger |first=Franziska |display-authors=etal |year=2021 |title=Making the sun shine at night: comparing the cost of dispatchable concentrating solar power and photovoltaics with storage |journal=Energy Sources, Part B |volume=16 |issue=1 |pages=55–74 |bibcode=2021EneSB..16...55S |doi=10.1080/15567249.2020.1843565 |doi-access=free |hdl-access=free |hdl=20.500.12708/18282}}</ref> while [[NREL]] expects that by 2030 PV with 10-hour storage lithium batteries will cost the same as PV with 4-hour storage used to cost in 2020.<ref>{{citation |author=Andy Colthorpe |title=US National Renewable Energy Lab forecasts rapid cost reduction for battery storage to 2030 |date=July 14, 2021 |url=https://www.energy-storage.news/news/us-national-renewable-energy-lab-forecasts-rapid-cost-reduction-for-battery |publisher=Solar Media Limited}}</ref> Countries with no PV cell production capability and low labour cost may reduce substantially the local CSP/PV cost gap.

== Efficiency ==
The efficiency of a concentrating solar power system depends on the technology used to convert the solar power to electrical energy, the operating temperature of the receiver and the heat rejection, thermal losses in the system, and the presence or absence of other system losses; in addition to the conversion efficiency, the optical system which concentrates the sunlight will also add additional losses.

Real-world systems claim a maximum thermal to electrical conversion efficiency of 23-35% for "power tower" type systems, operating at temperatures from 250 to 565&nbsp;°C, with the higher efficiency number assuming a combined cycle turbine. Dish Stirling systems, operating at temperatures of 550-750&nbsp;°C, claim an efficiency of about 30%,<ref name=IRENA2012>International Renewable Energy Agency, "Table 2.1: Comparison of different CSP Technologies", in [https://www.irena.org/documentdownloads/publications/re_technologies_cost_analysis-csp.pdf Concentrating Solar Power, Volume 1: Power Sector] {{Webarchive|url=https://web.archive.org/web/20190523203125/https://www.irena.org/documentdownloads/publications/re_technologies_cost_analysis-csp.pdf |date=23 May 2019 }}, Renewable energy technologies: Cost analysis series, June 2012, p. 10. Retrieved 23 May 2019.</ref> with the record solar-to-grid conversion efficiency of 31.25%, "the highest recorded efficiency for any field solar technology" set by [[Sandia National Laboratories|Sandia]] in 2008,<ref>Andraka, C. E. and Powell, M. P., (2008). “Dish Stirling Development for Utility-Scale Commercialization,” 14th Biennial CSP SolarPACES Symposium, Las Vegas, NV.  See: https://newsreleases.sandia.gov/releases/2008/solargrid.html. Also reported in https://www.osti.gov/servlets/purl/1431429 (2016)</ref> and a slightly slightly higher record of 31.4% solar-to-electric system efficiency reported by the U.S. Deparment of Energy.<ref>[https://www.energy.gov/eere/solar/dish-engine Dish Engine], U.S. Department of Energy (2017). Retrieved 31 January 2025.</ref>

Due to variation in sun incidence during the day, the average conversion efficiency achieved is not equal to these maximum efficiencies, and the net annual solar-to-electricity efficiencies are 7-20% for pilot power tower systems, and 12-25% for demonstration-scale Stirling dish systems.<ref name=IRENA2012 />

===Theory===
The solar energy to electrical power conversion efficiency is the product of several factors: the fraction of solar energy captured (accounting for optical losses in the solar concentration system), the heating efficiency (accounting for thermal losses in the element receiving the solar energy), and the thermal conversion efficiency (the efficiency of converting heat energy to electrical power).

The maximum conversion efficiency of any thermal to electrical energy system is given by the [[Carnot efficiency]], which represents a theoretical limit to the efficiency that can be achieved by any system, set by the [[laws of thermodynamics]]. Real-world systems do not achieve the Carnot efficiency.

The conversion efficiency <math>\eta</math> of the incident solar radiation into mechanical work depends on the [[thermal radiation]] properties of the solar receiver and on the heat engine (''e.g.'' steam turbine). 
[[Solar irradiation]] is first concentrated onto the receiver by an optical system and converted into heat by the solar receiver with the efficiency <math>\eta_{Receiver}</math>, and subsequently the heat is converted into mechanical energy by the heat engine with the efficiency <math>\eta_{mechanical}</math>, using [[Carnot's theorem (thermodynamics)|Carnot's principle]].<ref>{{cite journal |author=E. A. Fletcher |date= 2001 |title= Solar thermal processing: A review |doi=10.1115/1.1349552 |journal=Journal of Solar Energy Engineering |volume=123 |issue=2 |page=63}}</ref><ref>{{cite journal |author=Aldo Steinfeld |author2=Robert Palumbo |name-list-style=amp |date=2001 |title=Solar Thermochemical Process Technology |journal=Encyclopedia of Physical Science & Technology, R.A. Meyers Ed. |publisher=Academic Press |volume=15 |pages=237–256 |url=http://pre.ethz.ch/publications/0_pdf/books/Solar_Thermochemical_Process_Technology.pdf |archive-url=https://web.archive.org/web/20140719132827/http://www.pre.ethz.ch/publications/0_pdf/books/Solar_Thermochemical_Process_Technology.pdf |archive-date=19 July 2014 }}</ref> The mechanical energy is then converted into electrical energy by a generator.
For a solar receiver with a mechanical converter (''e.g.'', a turbine), the overall conversion efficiency can be defined as follows:

:<math>\eta = \eta_\mathrm{optics}\cdot\eta_\mathrm{receiver} \cdot \eta_\mathrm{mechanical} \cdot \eta_\mathrm{generator} </math>

where <math>\eta_\mathrm{optics} </math> represents the fraction of incident light concentrated onto the receiver, <math>\eta_\mathrm{receiver}</math> the fraction of light incident on the receiver that is converted into heat energy, <math>\eta_\mathrm{mechanical} </math> the efficiency of conversion of heat energy into mechanical energy, and <math>\eta_\mathrm{generator} </math> the efficiency of converting the mechanical energy into electrical power.

<math>\eta_\mathrm{receiver}</math> is:
:<math>\eta_\mathrm{receiver} = \frac{Q_\mathrm{absorbed}-Q_\mathrm{lost}}{Q_\mathrm{incident}}</math>
::with <math>Q_\mathrm{incident}</math>, <math>Q_\mathrm{absorbed}</math>, <math>Q_\mathrm{lost}</math> respectively the incoming [[solar flux]] and the fluxes absorbed and lost by the system solar receiver.

The conversion efficiency <math>\eta_\mathrm{mechanical} </math> is at most the Carnot efficiency, which is determined by the temperature of the receiver <math>T_H</math> and the temperature of the heat rejection ("heat sink temperature") <math>T^0</math>,
: <math>\eta_\mathrm{Carnot} = 1 - \frac{T^0}{T_H} </math>

The real-world thermal-conversion efficiencies of typical engines achieve 50% to at most 70% of the Carnot efficiency due to losses such as heat loss and windage in the moving parts.

===Ideal case===
For a solar flux <math>I</math> (e.g. <math>I = 1000\, \mathrm{W/m^2}</math>) concentrated <math>C</math> times with an efficiency <math>\eta_{Optics}</math> on the system solar receiver with a collecting area <math>A</math> and an [[Absorbance|absorptivity]] <math>\alpha</math>:
:<math>Q_\mathrm{solar} = I C A </math>,
:<math>Q_\mathrm{absorbed} = \eta_\mathrm{optics} \alpha Q_\mathrm{solar} </math>,
For simplicity's sake, one can assume that the losses are only radiative ones (a fair assumption for high temperatures), thus for a reradiating area ''A'' and an [[emissivity]] <math>\epsilon</math> applying the [[Stefan–Boltzmann law]] yields:
:<math>Q_\mathrm{lost} = A \epsilon \sigma T_H^4 </math>

Simplifying these equations by considering perfect optics (<math>\eta_\mathrm{Optics}</math> = 1) and without considering the ultimate conversion step into electricity by a generator, collecting and reradiating areas equal and maximum absorptivity and emissivity (<math>\alpha</math> = 1, <math>\epsilon</math> = 1) then substituting in the first equation gives
:<math>\eta = \left(1 - \frac {\sigma T_H^4 }{IC} \right) \cdot \left( 1 - \frac{T^0}{T_H} \right)</math>

[[File:Solar concentration efficiency.png|400px]]

The graph shows that the overall efficiency does not increase steadily with the receiver's temperature. Although the heat engine's efficiency (Carnot) increases with higher temperature, the receiver's efficiency does not. On the contrary, the receiver's efficiency is decreasing, as the amount of energy it cannot absorb (Q<sub>lost</sub>) grows by the fourth power as a function of temperature. Hence, there is a maximum reachable temperature. When the receiver efficiency is null (blue curve on the figure below), T<sub>max</sub> is:
<math> T_\mathrm{max} = \left({\frac {IC}{\sigma}} \right)^{0.25} </math>

There is a temperature T<sub>opt</sub> for which the efficiency is maximum, ''i.e.''. when the efficiency derivative relative to the receiver temperature is null:
:<math>\frac{d\eta}{dT_H}(T_\mathrm{opt}) = 0 </math>
Consequently, this leads us to the following equation:
:<math>T_{opt}^5-(0.75T^0)T_\mathrm{opt}^4-\frac{T^0IC}{4\sigma} = 0 </math>
Solving this equation numerically allows us to obtain the optimum process temperature according to the solar concentration ratio <math>C</math> (red curve on the figure below)

{| class="wikitable floatright" style="text-align: center; width: 25%;"
|-
! scope=row|C
| 500 || 1000 || 5000 || 10000 || 45000 <small>(max. for Earth)</small>
|-
! scope=row|T<sub>max</sub>
| 1720 || 2050 || 3060 || 3640 || 5300
|-
! scope=row|T<sub>opt</sub>
| 970 || 1100 || 1500 || 1720 || 2310
|}

[[File:SolarConcentration max opt temperatures.png|400px]]

Theoretical efficiencies aside, real-world experience of CSP reveals a 25%–60% shortfall in projected production, a good part of which is due to the practical Carnot cycle losses not included in the above analysis.

== Incentives and markets ==
=== Spain ===
[[File:Andasol 5.jpg|thumb|Andasol Solar Power Station in Spain]]
In 2008, Spain launched the first commercial scale CSP market in Europe. Until 2012, solar-thermal electricity generation was initially eligible for feed-in tariff payments (art. 2 RD 661/2007) – leading to the creation of the largest CSP fleet in the world which at 2.3 GW of installed capacity contributes about 5TWh of power to the Spanish grid every year.<ref>[https://www.solarpaces.org/generation-from-spains-existing-2-3-gw-of-csp-showing-steady-annual-increases/] Generation from Spain's Existing 2.3 GW of CSP Showing Steady Annual Increases.</ref>
The initial requirements for plants in the FiT were:
* Systems registered in the register of systems prior to 29 September 2008: 50&nbsp;MW for solar-thermal systems.
* Systems registered after 29 September 2008 (PV only).
The capacity limits for the different system types were re-defined during the review of the application conditions every quarter (art. 5 RD 1578/2008, Annex III RD 1578/2008). Prior to the end of an application period, the market caps specified for each system type are published on the website of the Ministry of Industry, Tourism and Trade (art. 5 RD 1578/2008).<ref>[https://web.archive.org/web/20120427001457/http://res-legal.de/en/search%2Dfor%2Dcountries/spain/single/land/spanien/instrument/price%2Dregulation%2Dregimen%2Despecial/ueberblick/foerderung.html?bmu%5BlastPid%5D%3D97%26bmu%5BlastShow%5D%3D1%26cHash%3D0eefe5ac972c28a4b783b540f3d49b3d#91%3BlastPid%26 Feed-in tariff (Régimen Especial)]. res-legal.de (12 December 2011).</ref> Because of cost concerns Spain has halted acceptance of new projects for the feed-in-tariff on 27 January 2012<ref>[http://www.solarserver.com/solar-magazine/solar-news/current/2012/kw05/spanish-government-halts-pv-csp-feed-in-tariffs.html Spanish government halts PV, CSP feed-in tariffs] {{webarchive|url=https://web.archive.org/web/20120805025439/http://www.solarserver.com/solar-magazine/solar-news/current/2012/kw05/spanish-government-halts-pv-csp-feed-in-tariffs.html |date=5 August 2012 }}. Solarserver.com (30 January 2012). Retrieved on 22 April 2013.</ref><ref>[http://www.instituteforenergyresearch.org/2012/04/09/spain-halts-feed-in-tariffs-for-renewable-energy/ Spain Halts Feed-in-Tariffs for Renewable Energy]. Instituteforenergyresearch.org (9 April 2012). Retrieved on 22 April 2013.</ref> Already accepted projects were affected by a 6% "solar-tax" on feed-in-tariffs, effectively reducing the feed-in-tariff.<ref>[http://www.evwind.es/2012/09/14/spain-introduces-6-energy-tax/23453/ Spain introduces 6% energy tax]. Evwind.es (14 September 2012). Retrieved on 22 April 2013.</ref>

In this context, the Spanish Government enacted the Royal Decree-Law 9/2013<ref>Royal Decree-Law 9/2013, of 12 July, BOE no. 167, July 13; 2013. https://www.boe.es/eli/es/rdl/2013/07/12/9</ref> in 2013, aimed at the adoption of urgent measures to guarantee the economic and financial stability of the electric system, laying the foundations of the new Law 24/2013 of the Spanish electricity sector.<ref>Law 24/2013, of 26 December, BOE no. 310, December 27; 2013. https://www.boe.es/eli/es/l/2013/12/26/24/con</ref> This new retroactive legal-economic framework applied to all the renewable energy systems was developed in 2014 by the RD 413/2014,<ref>Royal Decree 413/2014, of 6 June, BOE no. 140, June 10; 2014. https://www.boe.es/eli/es/rd/2014/06/06/413</ref> which abolished the former regulatory frameworks set by the RD 661/2007 and the RD 1578/2008 and defined a new remuneration scheme for these assets.

After a lost decade for CSP in Europe, Spain announced in its National Energy and Climate Plan with the intention of adding 5GW of CSP capacity between 2021 and 2030.<ref>{{cite web|url=https://ec.europa.eu/energy/sites/ener/files/documents/ec_courtesy_translation_es_necp.pdf |archive-url=https://web.archive.org/web/20200318000154/https://ec.europa.eu/energy/sites/ener/files/documents/ec_courtesy_translation_es_necp.pdf |archive-date=18 March 2020 |title=Spanish National Energy and Climate Plan|url-status=dead}}</ref> Towards this end bi-annual auctions of 200 MW of CSP capacity starting in October 2022 are expected, but details are not yet known.<ref>{{Cite web|url=https://www.miteco.gob.es/es/prensa/ultimas-noticias/el-miteco-aprueba-la-orden-para-iniciar-el-calendario-de-subastas/tcm:30-518261|title=El Miteco aprueba la orden para iniciar el calendario de subastas|website=Miteco.gob.es}}</ref>

=== Australia ===
{{Main|Solar power in Australia}}
Several CSP dishes have been set up in remote Aboriginal settlements in the [[Northern Territory]]: [[Hermannsburg, Northern Territory|Hermannsburg]], [[Yuendumu]] and [[Lajamanu]].

So far no commercial scale CSP project has been commissioned in Australia, but several projects have been suggested. In 2017, now-bankrupt American CSP developer [[SolarReserve]] was awarded a [[Power purchase agreement|PPA]] to realize the 150 MW [[Aurora Solar Thermal Power Project]] in South Australia at a record low rate of just AUD$ 0.08/kWh, or close to USD$ 0.06/kWh.<ref>Kraemer, S. (2017). SolarReserve Breaks CSP Price Record with 6 Cent Contract, Solarpaces [http://www.solarpaces.org/solarreserve-breaks-csp-price-record-6-cent-contract]</ref> Unfortunately the company failed to secure financing, and the project was cancelled. Another promising application for CSP in Australia are mines that need 24/7 electricity but often have no grid connection. Vast Solar, a startup company aiming to commercialize a novel modular third generation CSP design,<ref>Kraemer, S. (2019). Sodium-based Vast Solar Combines the Best of Trough & Tower CSP to Win our Innovation Award, Solarpaces [https://www.solarpaces.org/sodium-based-vast-solar-combines-the-best-of-trough-tower-csp-to-win-our-innovation-award/]</ref><ref>New Energy Update (2019). CSP mini tower developer predicts costs below $50/MWh [https://www.reutersevents.com/renewables/csp-today/csp-mini-tower-developer-predicts-costs-below-50mwh]</ref> is looking to start construction of a 50 MW combined CSP and PV facility in [[Mt. Isa]] of North-West Queensland in 2021.<ref>PV magazine (2020). Vast Solar eyes $600 million solar hybrid plant for Mount Isa [https://www.pv-magazine-australia.com/2020/07/21/vast-solar-eyes-600-million-solar-hybrid-plant-for-mount-isa/]</ref>

At the federal level, under the Large-scale Renewable Energy Target (LRET), in operation under the Renewable Energy Electricity Act 2000, large-scale solar thermal electricity generation from accredited RET power stations may be entitled to create large-scale generation certificates (LGCs). These certificates can then be sold and transferred to liable entities (usually electricity retailers) to meet their obligations under this tradeable certificates scheme. However, as this legislation is technology neutral in its operation, it tends to favour more established RE technologies with a lower levelised cost of generation, such as large-scale onshore wind, rather than solar thermal and CSP.<ref>[https://ssrn.com/abstract=1408345 A Dangerous Obsession with Least Cost? Climate Change, Renewable Energy Law and Emissions Trading] Prest, J. (2009). in ''Climate Change Law: Comparative, Contractual and Regulatory Considerations'', W. Gumley & T. Daya-Winterbottom (eds.) Lawbook Company, {{ISBN|0455226342}}</ref>
At state level, [[renewable energy]] feed-in laws typically are capped by maximum generation capacity in kWp, and are open only to micro or medium scale generation and in a number of instances are only open to solar photovoltaic (PV) generation. This means that larger scale CSP projects would not be eligible for payment for feed-in incentives in many of the State and Territory jurisdictions.

=== China ===
[[File:50 MW molten-salt power tower in hami.jpg|thumb|right|The China Energy Engineering Corporation 50 MW Hami power tower has 8 hours of molten-salt storage]]
{{Main|Solar power in China#Concentrated solar power}}
In 2024, China is offering second generation CSP technology to compete with other on-demand electricity generation methods based on renewable or non-renewable fossil fuels without any direct or indirect subsidies.<ref name=chcsp/> In the current 14th [[Five-year plans of China|five-year plan]] CSP projects are developed in several provinces alongside large GW sized solar PV and wind projects.<ref name=chintar/><ref name=chinCSP/>

In 2016, China announced its intention to build a batch of 20 technologically diverse CSP demonstration projects in the context of the 13th [[Five-year plans of China|five-year plan]], with the intention of building up an internationally competitive CSP industry.<ref>The dragon awakens: Will China save or conquer concentrating solar power? https://doi.org/10.1063/1.5117648</ref> Since the first plants were completed in 2018, the generated electricity from the plants with thermal storage is supported with an administratively set [[Feed-in tariff|FiT]] of [[Renminbi|RMB]] 1.5 per&nbsp;kWh.<ref>{{cite web| url=http://www.cspfocus.cn/en/market/detail_1231.htm |title=2018 Review: China concentrated solar power pilot projects' development |access-date=15 January 2019}}</ref> At the end of 2020, China operated a total of 545 MW in 12 CSP plants:<ref>Johan Lilliestam, Richard Thonig, Alina Gilmanova, & Chuncheng Zang. (2020). CSP.guru (Version 2020-07-01) [Data set]. Zenodo. http://doi.org/10.5281/zenodo.4297966</ref><ref name=Thonig2022>{{cite journal|last1=Thonig|first1=Richard|last2=Gilmanova|first2=Alina|last3=Zhan|first3=Jing| last4=Lilliestam|first4=Johan |title=Chinese CSP for the World?|journal=AIP Conference Proceedings|series=Solarpaces 2020: 26th International Conference on Concentrating Solar Power and Chemical Energy Systems |date=May 2022|volume=2445 |issue=1 |page=050007 |doi=10.1063/5.0085752|bibcode=2022AIPC.2445e0007T |s2cid=248768163 |doi-access=}}</ref> seven plants (320 MW) are molten-salt towers, another two plants (150 MW) use the proven Eurotrough 150 parabolic trough design,<ref>Solarpaces (2021),
EuroTrough Helped Cut Ramp-Up Time of China's 100 MW Urat CSP https://www.solarpaces.org/eurotrough-cut-ramp-up-in-china-100-mw-urat-csp%E2%80%A8</ref> and three plants (75 MW) use linear Fresnel collectors. Plans to build a second batch of demonstration projects were never enacted and further technology specific support for CSP in the upcoming 14th [[Five-year plans of China|five-year plan]] is unknown. Federal support projects from the demonstration batch ran out at the end of 2021.<ref>HeliosCSP (2020) China mulls withdrawal of subsidies for concentrated solar power (CSP) and offshore wind energy in 2021 http://helioscsp.com/china-mulls-withdrawal-of-subsidies-for-concentrated-solar-power-csp-and-offshore-wind-energy-in-2021/</ref>

===India===
In March 2024, [[Solar Energy Corporation of India|SECI]] announced that a [[Request for quotation |RfQ]] for 500 MW would be called in the year 2024.<ref>{{cite web |url=https://energy.economictimes.indiatimes.com/news/renewable/seci-to-issue-tender-for-500-mw-concentrated-solar-thermal-power-project/108189940?utm_source=most_read&utm_medium=sectionListing|title=SECI to issue tender for 500-MW concentrated solar-thermal power project
|date=4 March 2024 |access-date= 7 March 2024 }}</ref>

== Solar thermal reactors ==
CSP has other uses than electricity. Researchers are investigating [[Water splitting#Solar-thermal|solar thermal reactor]]s for the production of solar fuels, making solar a fully transportable form of energy in the future. These researchers use the solar heat of CSP as a catalyst for thermochemistry to break apart molecules of H<sub>2</sub>O to create hydrogen (H<sub>2</sub>) from solar energy with no carbon emissions.<ref>{{Cite news|url= https://www.solarpaces.org/csp-efficient-solar-split-h2o-hydrogen/ |title=CSP is the Most Efficient Renewable to Split Water for Hydrogen|last=Kraemer|first=Susan|date=21 December 2017|work=SolarPACES.org|access-date=3 August 2018}}</ref> By splitting both H<sub>2</sub>O and CO<sub>2</sub>, other much-used hydrocarbons – for example, the jet fuel used to fly commercial airplanes – could also be created with solar energy rather than from fossil fuels.<ref>{{Cite news|url= https://www.eurekalert.org/pub_releases/2017-11/s-dst111517.php |title=Desert solar to fuel centuries of air travel|last=EurekAlert! |date=15 November 2017|work=EurekAlert!|access-date=3 August 2018}}</ref>

Heat from the sun can be used to provide steam used to make heavy oil less viscous and easier to pump. This process is called [[solar thermal enhanced oil recovery]]. Solar power towers and parabolic troughs can be used to provide the steam, which is used directly, so no generators are required and no electricity is produced. Solar thermal enhanced oil recovery can extend the life of oilfields with very thick oil which would not otherwise be economical to pump.<ref name=":0" />

Carbon neutral synthetic fuel production using concentrated solar thermal energy at nearly 1500&nbsp;°C temperature is technically feasible and will be commercially viable in the future if the costs of CSP plants decline.<ref>{{Cite web |date=July 2022 |title=A solar tower fuel plant for the thermochemical production of kerosene from H<sub>2</sub>O and CO<sub>2</sub> |url=https://www.researchgate.net/publication/362150113 |access-date=7 March 2024}}</ref> Also, carbon-neutral hydrogen can be produced with solar thermal energy (CSP) using the [[sulfur–iodine cycle]], [[hybrid sulfur cycle]], [[iron oxide cycle]], [[copper–chlorine cycle]], [[zinc–zinc oxide cycle]], [[cerium(IV) oxide–cerium(III) oxide cycle]], or an alternative.
== Gigawatt-scale solar power plants ==
Around the turn of the millennium up to about 2010, there have been several proposals for gigawatt-size, very-large-scale solar power plants using CSP.<ref>{{cite web |url=https://www.power-technology.com/features/sahara-solar-battery-europe/ |title=The Sahara: a solar battery for Europe? |date=20 December 2017 |access-date=21 April 2018}}</ref> They include the Euro-Mediterranean [[Desertec]] proposal and Project Helios in Greece (10&nbsp;GW), both now canceled. A 2003 study concluded that the world could generate 2,357,840&nbsp;TWh each year from very large-scale solar power plants using 1% of each of the world's deserts. Total consumption worldwide was 15,223&nbsp;TWh/year<ref>[http://www.geni.org/globalenergy/library/energytrends/currentusage/renewable/solar/solar-systems-in-the-desert/Solar-Systems-in-the-Desert.pdf A Study of Very Large Solar Desert Systems with the Requirements and Benefits to those Nations Having High Solar Irradiation Potential]. geni.org.</ref> (in 2003). The gigawatt size projects would have been arrays of standard-sized single plants. In 2012, the [[Bureau of Land Management|BLM]] made available {{convert|97,921,069|acres|abbr=off}} of land in the [[southwestern United States]] for solar projects, enough for between 10,000 and 20,000&nbsp;GW.<ref>[http://solareis.anl.gov/maps/resource/ Solar Resource Data and Maps]. Solareis.anl.gov. Retrieved on 22 April 2013.{{Dubious|reason=Figure of 10,000 to 20,000&nbsp;GW not found in citation. Figure is purely hypothetical and needs to be presented as such|date=February 2015}}</ref> The largest single plant in operation is the 510&nbsp;MW [[Ouarzazate Solar Power Station|Noor Solar Power Station]]. In 2022 the 700&nbsp;MW CSP 4th phase of the 5GW [[Mohammed bin Rashid Al Maktoum Solar Park]] in Dubai will become the largest solar complex featuring CSP.

=== Suitable sites ===
The locations with highest direct irradiance are dry, at high altitude, and located in the [[tropics]]. These locations have a higher potential for CSP than areas with less sun.

Abandoned [[opencast mine]]s, moderate hill slopes, and crater depressions may be advantageous in the case of power tower CSP, as the power tower can be located on the ground integral with the molten salt storage tank.<ref>{{cite web |url=http://www.rechargenews.com/solar/837655/solar-heads-for-the-hills-as-tower-technology-turns-upside-down |title=Solar heads for the hills as tower technology turns upside down |date=30 January 2012 |access-date=21 August 2017}}</ref><ref>{{cite web |url=https://helioscsp.com/beam-down-demos-first-direct-solar-storage-at-1-2-mwh-scale/ |title=Beam-Down Demos First Direct Solar Storage at 1/2 MWh Scale |access-date=10 July 2021}}</ref>

== Environmental effects ==
CSP has a number of environmental impacts, particularly by the use of water and land.<ref>{{Cite web|url=https://www.ucsusa.org/resources/environmental-impacts-solar-power|title=Environmental Impacts of Solar Power &#124; Union of Concerned Scientists|website=UCSUSA.org}}</ref>
Water is generally used for cooling and to clean mirrors. Some projects are looking into various approaches to reduce the water and cleaning agents used, including the use of barriers, non-stick coatings on mirrors, water misting systems, and others.<ref>{{Cite web|url=https://www.euronews.com/2019/05/20/quenching-the-thirst-of-concentrated-solar-power-plants|title=Smart cooling and cleaning for concentrated solar power plants|first=Andrea|last=Bolitho|date=20 May 2019|website=euronews}}</ref>
 
===Water use===
Concentrating solar power plants with wet-cooling systems have the highest water-consumption intensities of any conventional type of electric power plant; only fossil-fuel plants with carbon-capture and storage may have higher water intensities.<ref>Nathan Bracken and others, Concentrating Solar Power and Water Issues in the U.S. Southwest, National Renewable Energy Laboratory, Technical Report NREL/TP-6A50-61376, March 2015, p.10.</ref> A 2013 study comparing various sources of electricity found that the median water consumption during operations of concentrating solar power plants with wet cooling was {{convert|810|usgal/MWh|m3/MWh|order=flip}} for power tower plants and {{convert|890|usgal/MWh|m3/MWh|order=flip|abbr=on}} for trough plants. This was higher than the operational water consumption (with cooling towers) for nuclear at {{convert|720|usgal/MWh|m3/MWh|order=flip|abbr=on}}, coal at {{convert|530|usgal/MWh|m3/MWh|order=flip|abbr=on}}, or natural gas at {{convert|210|usgal/MWh|m3/MWh|order=flip|abbr=on}}.<ref name="iopscience.iop.org">{{Cite journal|last1=Meldrum|first1=J.|last2=Nettles-Anderson|first2=S.|last3=Heath|first3=G.|last4=MacKnick|first4=J.|date=March 2013|title=Life cycle water use for electricity generation: A review and harmonization of literature estimates|journal=Environmental Research Letters|volume=8|issue=1|page=015031|bibcode=2013ERL.....8a5031M|doi=10.1088/1748-9326/8/1/015031|doi-access=free}}</ref> A 2011 study by the National Renewable Energy Laboratory came to similar conclusions: for power plants with cooling towers, water consumption during operations was {{convert|865|usgal/MWh|m3/MWh|order=flip|abbr=on}} for CSP trough, {{convert|786|usgal/MWh|m3/MWh|order=flip|abbr=on}} for CSP tower, {{convert|687|usgal/MWh|m3/MWh|order=flip|abbr=on}} for coal, {{convert|672|usgal/MWh|m3/MWh|order=flip|abbr=on}} for nuclear, and {{convert|198|usgal/MWh|m3/MWh|order=flip|abbr=on}} for natural gas.<ref>John Macknick and others, [http://www.nrel.gov/docs/fy11osti/50900.pdf A Review of Operational Water Consumption and Withdrawal Factors for Electricity Generating Technologies] {{webarchive|url=https://web.archive.org/web/20150406000614/http://www.nrel.gov/docs/fy11osti/50900.pdf |date=6 April 2015 }}, National Renewable Energy Laboratory, Technical Report NREL/TP-6A20-50900.</ref> The Solar Energy Industries Association noted that the Nevada Solar One trough CSP plant consumes {{convert|850|usgal/MWh|m3/MWh|order=flip|abbr=on}}.<ref>Utility-Scale Solar Power: Responsible Water Resource Management, Solar Energy Industries Association, 18 March 2010.</ref> The issue of water consumption is heightened because CSP plants are often located in arid environments where water is scarce.

In 2007, the US Congress directed the Department of Energy to report on ways to reduce water consumption by CSP. The subsequent report noted that dry cooling technology was available that, although more expensive to build and operate, could reduce water consumption by CSP by 91 to 95 percent. A hybrid wet/dry cooling system could reduce water consumption by 32 to 58 percent.<ref>[https://www1.eere.energy.gov/solar/pdfs/csp_water_study.pdf Concentrating Solar Power Commercial Application Study] {{webarchive|url=https://web.archive.org/web/20171226021735/https://www1.eere.energy.gov/solar/pdfs/csp_water_study.pdf |date=26 December 2017 }}, US Department of Energy, 20 Feb. 2008.</ref> A 2015 report by NREL noted that of the 24 operating CSP power plants in the US, 4 used dry cooling systems. The four dry-cooled systems were the three power plants at the [[Ivanpah Solar Power Facility]] near [[Barstow, California]], and the [[Genesis Solar Energy Project]] in [[Riverside County, California]]. Of 15 CSP projects under construction or development in the US as of March 2015, 6 were wet systems, 7 were dry systems, 1 hybrid, and 1 unspecified.

Although many older thermoelectric power plants with once-through cooling or cooling ponds ''use'' more water than CSP, meaning that more water passes through their systems, most of the cooling water returns to the water body available for other uses, and they ''consume'' less water by evaporation. For instance, the median coal power plant in the US with once-through cooling uses {{convert|36,350|usgal/MWh|m3/MWh|order=flip|abbr=on|sigfig=3}}, but only {{convert|250|usgal/MWh|m3/MWh|order=flip|abbr=on}} (less than one percent) is lost through evaporation.<ref>John Macknick and others, [https://www.nrel.gov/docs/fy11osti/50900.pdf A Review of Operational Water Consumption and Withdrawal Factors for Electricity Generating Technologies] {{webarchive|url=https://web.archive.org/web/20170809222054/http://www.nrel.gov/docs/fy11osti/50900.pdf |date=9 August 2017 }}, NREL, Technical Report NREL/TP-6A20-50900.</ref>

=== Effects on wildlife ===
[[File:Warbler burned mid-air by solar thermal power plant.jpg|thumb|Dead warbler burned in mid-air by solar thermal power plant]]

Insects can be attracted to the bright light caused by concentrated solar technology, and as a result birds that hunt them can be killed by being burned if they fly near the point where light is being focused. This can also affect [[Bird of prey|raptors]] that hunt the birds.<ref>{{cite web |url=http://www.nbcnews.com/science/environment/burned-birds-become-new-environmental-victims-energy-quest-n184426 |title=Burned birds become new environmental victims of the energy quest |first=John |last=Roach |work=NBC News|date=20 August 2014 }}</ref><ref>{{cite web |url=http://www.esquire.com/blogs/news/solar-plant-dead-birds-081914 |title=Solar thermal plants have a PR problem, and that PR problem is dead birds catching on fire |first=Michael |last=Howard |date=20 August 2014|work=Esquire}}</ref><ref>{{cite web |url= https://www.foxnews.com/science/emerging-solar-plants-scorch-birds-in-mid-air/ |title=Emerging solar plants scorch birds in mid-air |work=Fox News|date=24 March 2015 }}</ref><ref>{{cite web|url=http://bigstory.ap.org/article/emerging-solar-plants-scorch-birds-mid-air|title=Associated Press News|website=bigstory.ap.org|access-date=8 September 2014|archive-date=8 September 2014|archive-url=https://web.archive.org/web/20140908235404/http://bigstory.ap.org/article/emerging-solar-plants-scorch-birds-mid-air|url-status=dead}}</ref> Federal wildlife officials were quoted by opponents as calling the Ivanpah power towers "mega traps" for wildlife.<ref>{{cite web |url= http://www.natureworldnews.com/articles/12918/20150223/solar-farm-set-hundreds-birds-ablaze.htm |title=How a solar farm set hundreds of birds ablaze |work=Nature World News}}</ref><ref>{{Cite web|url=https://spectrum.ieee.org/ivanpah-solar-plant-turns-birds-into-smoke-streamers|title=Full Page Reload|website=IEEE Spectrum: Technology, Engineering, and Science News|date=20 August 2014 }}</ref><ref>{{cite web |url=http://www.kcet.org/news/redefine/rewire/Avian-mortality%20Report%20FINALclean.pdf |title=Avian Mortality at Solar Energy Facilities in Southern California: A Preliminary Analysis |website=www.kcet.org |access-date=17 January 2022 |archive-url=https://web.archive.org/web/20150303225011/http://www.kcet.org/news/redefine/rewire/Avian-mortality%20Report%20FINALclean.pdf |archive-date=3 March 2015 }}</ref>

Some media sources have reported that concentrated solar power plants have injured or killed large numbers of birds due to intense heat from the concentrated sunrays.<ref>{{cite web|date=18 August 2014|title=Solar plant's downside? Birds igniting in midair|url=http://www.cbsnews.com/news/calif-solar-power-plants-scorching-birds-in-midair/|url-status=live|archive-url=https://web.archive.org/web/20140819082723/http://www.cbsnews.com/news/calif-solar-power-plants-scorching-birds-in-midair/|archive-date=19 August 2014|publisher=CBS News|df=dmy-all}}</ref><ref>{{cite web|date=20 August 2014|title=California's new solar power plant is actually a death ray that's incinerating birds mid-flight|url=http://www.extremetech.com/extreme/188328-californias-new-solar-power-plant-is-actually-a-death-ray-thats-incinerating-birds-mid-flight|url-status=live|archive-url=https://web.archive.org/web/20141019003407/http://www.extremetech.com/extreme/188328-californias-new-solar-power-plant-is-actually-a-death-ray-thats-incinerating-birds-mid-flight|archive-date=19 October 2014|publisher=ExtremeTech.com|df=dmy-all}}</ref> Some of the claims may have been overstated or exaggerated.<ref>{{cite web|author=Jake Richardson|date=22 August 2014|title=Bird deaths from solar plant exaggerated by some media sources|url=http://cleantechnica.com/2014/08/22/bird-deaths-solar-plant-exaggerated-media-sources/|publisher=Cleantechnica.com}}</ref>

According to rigorous reporting, in over six months of its first year of operation, 321 bird fatalities were counted at Ivanpah, of which 133 were related to sunlight being reflected onto the boilers.<ref>{{cite web |url=https://www.renewableenergyworld.com/storage/for-the-birds-how-speculation-trumped-fact-at-ivanpah |title=For the birds: How speculation trumped fact at Ivanpah |website=RenewableEnergyWorld.com |date=3 September 2014 |access-date=4 May 2015}}</ref> Over a year, this figure rose to a total count of 415 bird fatalities from known causes, and 288 from unknown causes. Taking into account the search efficiency of the dead bird carcasses, the total avian mortality for the first year was estimated at 1492 for known causes and 2012 from unknown causes. Of the bird deaths due to known causes, 47.4% were burned, 51.9% died of collision effects, and 0.7% died from other causes.<ref>{{cite journal |url=https://www.osti.gov/servlets/purl/1364837 |title=Review of Avian Mortality Studies at Concentrating Solar Power Plants |last1=Ho |first1=Clifford K. |journal=[[AIP Conference Proceedings]] |volume=1734 |issue=1 |pages= |doi=10.1063/1.4949164 |date=31 May 2016 |bibcode=2016AIPC.1734g0017H |access-date=11 November 2024 }}</ref> Mitigations actions can be taken to reduce these numbers, such as focusing no more than four mirrors on any one place in the air during standby, as was done at [[Crescent Dunes Solar Energy Project]].<ref>{{cite web |url=http://cleantechnica.com/2015/04/16/one-weird-trick-prevents-bird-deaths-solar-towers/ |title=One weird trick prevents bird deaths at solar towers |website=CleanTechnica.com |date=16 April 2015 |access-date=4 May 2015 }}</ref> Over the 2020-2021 period, 288 bird fatalities were directly accounted for at Ivanpah, a figure consistent with the ranges found in previous annual assessments.<ref>{{cite report |author=California Energy Commission |date=1 April 2023 |title=IVANPAH SOLAR ELECTRIC GENERATING SYSTEM AVIAN & BAT MONITORING PLAN 2020 – 2021 Annual Report Year 8 |url=https://efiling.energy.ca.gov/GetDocument.aspx?tn=248302&DocumentContentId=82662 |access-date=11 November 2024}}</ref> To put this in perspective, alone in Germany, every year up to 2 million birds die interacting with overhead [[Overhead power line|power lines]].<ref>{{cite web |url=https://www.euronatur.org/en/what-we-do/news/power-lines-fatal-for-migratory-birds |title=Power lines: Fatal for migratory birds  |date=19 August 2019 | publisher=EuroNatur Foundation  |access-date=27 October 2024}}</ref> In more general terms, a 2016 preliminary study assessed that the annual bird mortality per [[Watt#Megawatt|MW]] of installed power was similar between U.S. concentrated solar power plants and wind power plants, and higher for fossil fuel power plants.<ref>{{cite journal |last1=Walston |first1=Leroy J. |last2=Rollins |first2=Katherine E. |date=July 2016 |title=A preliminary assessment of avian mortality at utility-scale solar energy facilities in the United States |journal=[[Renewable_Energy_(journal)|Renewable Energy]] |volume=92 |issue= |pages=405–414 |doi=10.1016/j.renene.2016.02.041 |bibcode=2016REne...92..405W |doi-access=free }}</ref>

== See also ==
{{Portal|Renewable energy|Energy}}
{{div col|colwidth=30em}}
* [[Dover Sun House]]
* [[Concentrator photovoltaics]] (CPV)
* [[Daylighting (architecture)|Daylighting]]
* [[List of concentrating solar thermal power companies]]
* [[List of solar thermal power stations]]
* [[Luminescent solar concentrator]]
* [[Salt evaporation pond]]
* [[Solar air conditioning]]
* [[Solar thermal energy]]
* [[Solar thermal collector]]
* [[Solar water heating]]
* [[Thermal energy storage]]
* [[Thermochemical cycle]]
*[[Particle receiver]]
{{div col end}}

== References ==
{{Reflist}}

== External links ==
* [http://concentratingsolarpowerutility.com/ Concentrating Solar Power Utility] 
* [http://www.nrel.gov/csp NREL Concentrating Solar Power Program]
* [http://www.psa.es Plataforma Solar de Almeria, CSP research center]
* [http://www.isfoc.es ISFOC (Institute of Concentrating Photovoltaic Systems)]
* {{Cite web|url=https://medium.com/luszol/innovations-on-concentrated-solar-thermal-power-43fba525fc29|title=Innovations on Concentrated Solar Thermal Power|last=Baldizon|first=Roberto|date=2019-03-05|website=Medium|language=en|access-date=2020-01-18|ref=none}}

{{Solar energy}}
{{Emerging technologies|energy=yes}}
{{Renewable energy by country}}

{{Authority control}}

[[Category:Solar thermal energy|*]]
[[Category:Solar architecture]]
[[Category:Solar power]]
[[Category:Solar power stations]]
[[Category:French inventions]]