Concentrated Solar Power
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Concentrated solar power (CSP, also known as concentrating solar power, concentrated solar thermal) systems generate
solar power Solar power is the conversion of energy from sunlight into electricity, either directly using photovoltaics (PV) or indirectly using concentrated solar power. Photovoltaic cells convert light into an electric current using the photovoltaic e ...
by using mirrors or lenses to concentrate a large area of sunlight into a receiver.
Electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...
is generated when the concentrated light is converted to heat (
solar thermal energy Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy for use in industry, and in the residential and commercial sectors. Solar thermal collectors are classified by the United St ...
), which drives a
heat engine In thermodynamics and engineering, a heat engine is a system that converts heat to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state ...
(usually a
steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...
) connected to an electrical
power generator Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery ( transmission, distribution, etc.) to end users or its sto ...
or powers a
thermochemical Thermochemistry is the study of the heat energy which is associated with chemical reactions and/or phase changes such as melting and boiling. A reaction may release or absorb energy, and a phase change may do the same. Thermochemistry focuses on ...
reaction. CSP had a global total installed capacity of 6,800  MW in 2021, up from 354 MW in 2005.
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
accounted for almost one third of the world's capacity, at 2,300 MW, despite no new capacity entering commercial operation in the country since 2013. The United States follows with 1,740 MW. Interest is also notable in North Africa and the Middle East, as well as China and India. The global market was initially dominated by parabolic-trough plants, which accounted for 90% of CSP plants at one point. Since about 2010, central power tower CSP has been favored in new plants due to its higher temperature operation – up to vs. trough's maximum of – which promises greater efficiency. Among the larger CSP projects are the Ivanpah Solar Power Facility (392 MW) in the United States, which uses
solar power tower A solar power tower, also known as 'central tower' power plant or 'heliostat' power plant, is a type of solar furnace using a tower to receive focused sunlight. It uses an array of flat, movable mirrors (called heliostats) to focus the sun's ra ...
technology without thermal energy storage, and the
Ouarzazate Solar Power Station Ouarzazate Solar Power Station (OSPS), also called Noor Power Station (نور, Arabic for light) is a solar power complex and auxiliary diesel fuel system located in the Drâa-Tafilalet region in Morocco, from Ouarzazate town, in Ghessat ru ...
in Morocco, which combines trough and tower technologies for a total of 510 MW with several hours of energy storage. As a thermal energy generating power station, CSP has more in common with thermal power stations such as coal, gas, or geothermal. A CSP plant can incorporate
thermal energy storage Thermal energy storage (TES) is achieved with widely different technologies. Depending on the specific technology, it allows excess thermal energy to be stored and used hours, days, months later, at scales ranging from the individual process, ...
, which stores energy either in the form of
sensible heat Sensible heat is heat exchanged by a body or thermodynamic system in which the exchange of heat changes the temperature of the body or system, and some macroscopic variables of the body or system, but leaves unchanged certain other macroscopic vari ...
or as
latent heat Latent heat (also known as latent energy or heat of transformation) is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process — usually a first-order phase transition. Latent heat can be understo ...
(for example, using
molten salt Molten salt is salt which is solid at standard temperature and pressure but enters the liquid phase due to elevated temperature. Regular table salt has a melting point of 801 °C (1474°F) and a heat of fusion of 520 J/g.< ...
), which enables these plants to continue to generate electricity whenever it is needed, day or night. This makes CSP a dispatchable form of solar. Dispatchable
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
is particularly valuable in places where there is already a high penetration of photovoltaics (PV), such as
California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
, because demand for electric power peaks near sunset just as PV capacity ramps down (a phenomenon referred to as
duck curve The duck curve is a graph of power production over the course of a day that shows the timing imbalance between peak demand and renewable energy production. Used in utility-scale electricity generation, the term was coined in 2012 by the Califor ...
). CSP is often compared to
photovoltaic Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially us ...
solar (PV) since they both use solar energy. While solar PV experienced huge growth in recent years due to falling prices, 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. However, CSP can more easily store energy during the night, making it more competitive with dispatchable generators and baseload plants. The DEWA project in Dubai, under construction in 2019, held the world record for lowest CSP price in 2017 at US$73 per MWh 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 Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the east a ...
reached below $50/MWh in 2017 auctions.


History

A legend has it that
Archimedes Archimedes of Syracuse (;; ) was a Greek mathematician, physicist, engineer, astronomer, and inventor from the ancient city of Syracuse in Sicily. Although few details of his life are known, he is regarded as one of the leading scientists ...
used a "burning glass" to concentrate sunlight on the invading Roman fleet and repel them from 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 away. The ship caught fire after a few minutes; however, historians continue to doubt the Archimedes story. In 1866,
Auguste Mouchout Augustin Mouchot (; ; 7 April 1825 – 4 October 1912) was a 19th-century French inventor of the earliest solar-powered engine, converting solar energy into mechanical steam power. Background Mouchot was born in Semur-en-Auxois, France on 7 Ap ...
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 John Ericsson (born Johan Ericsson; July 31, 1803 – March 8, 1889) was a Swedish-American inventor. He was active in England and the United States. Ericsson collaborated on the design of the railroad steam locomotive ''Novelty'', which com ...
and
Frank Shuman Frank Shuman (; January 23, 1862 – April 28, 1918) was an American inventor, engineer and solar energy pioneer known for his work on solar engines, especially those that used solar energy to heat water that would produce steam. Career In 189 ...
developed concentrating solar-powered dеvices for irrigation, refrigеration, and locomоtion. In 1913 Shuman finished a parabolic
solar thermal energy Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy for use in industry, and in the residential and commercial sectors. Solar thermal collectors are classified by the United St ...
station in Maadi, Egypt for irrigation. The first solar-power system using a mirror dish was built by 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. 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 MW with superheated steam at 100 bar and 500 °C. The 10 MW Solar One power tower was developed in Southern California in 1981. Solar One was converted into
Solar Two The SOLAR Project consists of the Solar One, Solar Two and Solar Tres solar thermal power plants based in the Mojave Desert, United States and Andalucía, Spain. The US Department of Energy (DOE) and a consortium of US utilities built the count ...
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. The parabolic-trough technology of the nearby
Solar Energy Generating Systems Solar Energy Generating Systems (SEGS) is a concentrated solar power plant in California, United States. With the combined capacity from three separate locations at 354 megawatt (MW), it was once the world's second largest solar thermal energy g ...
(SEGS), begun in 1984, was more workable. The 354 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 MW
Kimberlina Solar Thermal Energy Plant The 5 megawatt (MW) Kimberlina Solar Thermal Energy Plant in Bakersfield, California is the first commercial solar thermal power plant to be built by Areva Solar. Completed in 2008, the Kimberlina renewable energy solar boiler uses Compact Lin ...
opened in 2009. In 2007, 75 MW Nevada Solar One was built, a trough design and the first large plant since SEGS. Between 2009 and 2013, Spain built over 40 parabolic trough systems, standardized in 50 MW blocks. Due to the success of Solar Two, a commercial power plant, called 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 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 had included several hours of thermal storage. By 2015, prices for photovoltaic plants had fallen and PV commercial power was selling for of recent CSP contracts. However, increasingly, CSP was being bid with 3 to 12 hours of thermal energy storage, making CSP a dispatchable form of solar energy. 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 Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporization ...
). Concentrated-solar technology systems use
mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...
s or
lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
es with
tracking Tracking may refer to: Science and technology Computing * Tracking, in computer graphics, in match moving (insertion of graphics into footage) * Tracking, composing music with music tracker software * Eye tracking, measuring the position of t ...
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 A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many pow ...
(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 Solar air conditioning, or "solar-powered air conditioning", refers to any air conditioning (cooling) system that uses solar power. This can be done through passive solar design, solar thermal energy conversion, and photovoltaic conversion (sunli ...
. Concentrating technologies exist in four optical types, namely
parabolic trough A parabolic trough is a type of solar thermal collector that is straight in one dimension and curved as a parabola in the other two, lined with a polished metal mirror. The sunlight which enters the mirror parallel to its plane of symmetry is foc ...
, dish, concentrating linear Fresnel reflector, and
solar power tower A solar power tower, also known as 'central tower' power plant or 'heliostat' power plant, is a type of solar furnace using a tower to receive focused sunlight. It uses an array of flat, movable mirrors (called heliostats) to focus the sun's ra ...
.Types of solar thermal CSP plants
Tomkonrad.wordpress.com. Retrieved on 22 April 2013.
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.Roland Winston, Juan C. Miñano, Pablo G. Benitez (2004) ''Nonimaging Optics'', Academic Press, . For example, the parabolic-trough concentration gives about of the theoretical maximum for the design 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 Nonimaging optics (also called anidolic optics)Roland Winston et al., ''Nonimaging Optics'', Academic Press, 2004 R. John Koshel (Editor), ''Illumination Engineering: Design with Nonimaging Optics'', Wiley, 2013 is the branch of optics concerned wi ...
. 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.


Parabolic trough

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 For fluid power, a working fluid is a gas or liquid that primarily transfers force, motion, or mechanical energy. In hydraulics, water or hydraulic fluid transfers force between hydraulic components such as hydraulic pumps, hydraulic cylinders, a ...
(e.g.
molten salt Molten salt is salt which is solid at standard temperature and pressure but enters the liquid phase due to elevated temperature. Regular table salt has a melting point of 801 °C (1474°F) and a heat of fusion of 520 J/g.< ...
) is heated to as it flows through the receiver and is then used as a heat source for a power generation system. Trough systems are the most developed CSP technology. The
Solar Energy Generating Systems Solar Energy Generating Systems (SEGS) is a concentrated solar power plant in California, United States. With the combined capacity from three separate locations at 354 megawatt (MW), it was once the world's second largest solar thermal energy g ...
(SEGS) plants in California, the world's first commercial parabolic trough plants, Acciona's
Nevada Solar One Nevada Solar One is a concentrated solar power plant, with a nominal capacity of 64  MW and maximum steam turbine power output up to 72 MW net (75 MW gross), spread over an area of . The projected CO2 emissions avoided is equivalen ...
near
Boulder City, Nevada Boulder City is a city in Clark County, Nevada, United States. It is approximately southeast of Las Vegas. As of the 2020 United States Census, 2020 census, the population of Boulder City was 14,885. The city took its name from Boulder Canyon ( ...
, and
Andasol The Andasol solar power station is a 150-megawatt (MW) concentrated solar power station and Europe's first commercial plant to use parabolic troughs. It is located near Guadix in Andalusia, Spain, and its name is a portmanteau of Andalusia and So ...
, Europe's first commercial parabolic trough plant are representative, along with Plataforma Solar de Almería's SSPS-DCS test facilities in
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
.


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.Deloitte Touche Tohmatsu Ltd
"Energy & Resources Predictions 2012"
2 November 2011
Lightweight curved solar-reflecting mirrors are suspended from the ceiling of the glasshouse by wires. A 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. 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. GlassPoint Solar, the company that created the Enclosed Trough design, states its technology can produce heat for
Enhanced Oil Recovery Enhanced oil recovery (abbreviated EOR), also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. EOR can extract 30% to 60% or more of a reservoir's oil, compared to 20% to 40% using ...
(EOR) for about $5 per in sunny regions, compared to between $10 and $12 for other conventional solar thermal technologies.Goossens, Ehren
"Chevron Uses Solar-Thermal Steam to Extract Oil in California"
"Bloomberg", 3 October 2011


Solar power tower

A solar power tower consists of an array of dual-axis tracking reflectors (
heliostat A heliostat (from ''helios'', the Greek word for ''sun'', and ''stat'', as in stationary) is a device that includes a mirror, usually a plane mirror, which turns so as to keep reflecting sunlight toward a predetermined target, compensating ...
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 Molten salt is salt which is solid at standard temperature and pressure but enters the liquid phase due to elevated temperature. Regular table salt has a melting point of 801 °C (1474°F) and a heat of fusion of 520 J/g.< ...
. Optically a solar power tower is the same as a circular Fresnel reflector. The working fluid in the receiver is heated to 500–1000 °C () and then used as a heat source for a power generation or energy storage system. 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. The
Solar Two The SOLAR Project consists of the Solar One, Solar Two and Solar Tres solar thermal power plants based in the Mojave Desert, United States and Andalucía, Spain. The US Department of Energy (DOE) and a consortium of US utilities built the count ...
in Daggett, California and the CESA-1 in Plataforma Solar de Almeria Almeria, Spain, are the most representative demonstration plants. The Planta Solar 10 (PS10) in Sanlucar la Mayor, Spain, is the first commercial utility-scale solar power tower in the world. The 377 MW Ivanpah Solar Power Facility, located in the
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily in ...
, is the largest CSP facility in the world, and uses three power towers. Ivanpah generated only 0.652 TWh (63%) of its energy from solar means, and the other 0.388 TWh (37%) was generated by burning
natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
.


Fresnel reflectors

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. Fresnel reflectors can be used in various size CSPs. 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.


Dish Stirling

A dish Stirling or dish engine system consists of a stand-alone
parabolic reflector A parabolic (or paraboloid or paraboloidal) reflector (or dish or mirror) is a reflective surface used to collect or project energy such as light, sound, or radio waves. Its shape is part of a circular paraboloid, that is, the surface generated ...
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 and then used by a
Stirling engine A Stirling engine is a heat engine that is operated by the cyclic compression and expansion of air or other gas (the ''working fluid'') between different temperatures, resulting in a net conversion of heat energy to mechanical work. More specif ...
to generate power. 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 (USS) and Science Applications International Corporation (SAIC) dishes at
UNLV The University of Nevada, Las Vegas (UNLV) is a public land-grant research university in Paradise, Nevada. The campus is about east of the Las Vegas Strip. It was formerly part of the University of Nevada from 1957 to 1969. It includes the S ...
, and
Australian National University The Australian National University (ANU) is a public research university located in Canberra, the capital of Australia. Its main campus in Acton encompasses seven teaching and research colleges, in addition to several national academies and ...
's Big Dish in
Canberra Canberra ( ) is the capital city of Australia. Founded following the federation of the colonies of Australia as the seat of government for the new nation, it is Australia's largest inland city and the eighth-largest city overall. The ci ...
, 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. According to its developer, Ripasso Energy, a Swedish firm, in 2015 its Dish Sterling system being tested in the
Kalahari Desert The Kalahari Desert is a large semi-arid sandy savanna in Southern Africa extending for , covering much of Botswana, and parts of Namibia and South Africa. It is not to be confused with the Angolan, Namibian, and South African Namib coastal de ...
in South Africa showed 34% efficiency. The SES installation in Maricopa, Phoenix was the largest Stirling Dish power installation in the world until it was sold to United Sun Systems. Subsequently, larger parts of the installation have been moved to China as part of the huge energy demand.


Solar thermal enhanced oil recovery

Heat from the sun can be used to provide steam used to make heavy oil less viscous and easier to pump. Solar power tower 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.


CSP with thermal energy storage

In a CSP plant that includes storage, the solar energy is first used to heat the molten salt or synthetic oil which is stored providing thermal/heat energy at high temperature in insulated tanks. Later the hot molten salt (or oil) is used in a steam generator to produce steam to generate electricity by steam
turbo generator A turbo generator is an electric generator connected to the shaft of a steam turbine or gas turbine for the generation of electric power. Large steam-powered turbo generators provide the majority of the world's electricity and are also used b ...
as per requirement. 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 A load-following power plant, regarded as producing mid-merit or mid-priced electricity, is a power plant that adjusts its power output as demand for electricity fluctuates throughout the day. Load-following plants are typically in between base lo ...
or solar peaker plant. The thermal storage capacity is indicated in hours of power generation at
nameplate capacity Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity, or maximum effect, is the intended full-load sustained output of a facility such as a power station,
. Unlike
solar PV A photovoltaic system, also PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and co ...
or CSP without storage, the power generation from solar thermal storage plants is dispatchable and self-sustainable similar to coal/gas-fired power plants, but without the pollution. CSP with thermal energy storage plants can also be used as
cogeneration Cogeneration or combined heat and power (CHP) is the use of a heat engine or power station to generate electricity and useful heat at the same time. Cogeneration is a more efficient use of fuel or heat, because otherwise- wasted heat from elect ...
plants to supply both electricity and process steam round the clock. As of December 2018, CSP with thermal energy storage plants generation cost have ranged between 5 c € / kWh and 7 c € / kWh depending on good to medium solar radiation received at a location. Unlike solar PV plants, CSP with thermal energy storage plants can also be used economically round the clock to produce only process steam replacing pollution emitting
fossil fuels A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels ...
. CSP plant can also be integrated with solar PV for better synergy. CSP with thermal storage systems are also available using
Brayton cycle The Brayton cycle is a thermodynamic cycle that describes the operation of certain heat engines that have air or some other gas as their working fluid. The original Brayton engines used a piston compressor and piston expander, but modern gas tur ...
with air instead of steam for generating electricity and/or steam round the clock. These CSP plants are equipped with
gas turbine A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
to generate electricity. These are also small in capacity (<0.4 MW) with flexibility to install in few acres area. Waste heat from the power plant can also be used for process steam generation and
HVAC Heating, ventilation, and air conditioning (HVAC) is the use of various technologies to control the temperature, humidity, and purity of the air in an enclosed space. Its goal is to provide thermal comfort and acceptable indoor air quality. HV ...
needs. In case land availability is not a limitation, any number of these modules can be installed up to 1000 MW with
RAMS In engineering, RAMS (reliability, availability, maintainability and safety)concentrated solar thermal 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. Electricity is generated when ...
storage plants.


Carbon neutral fuels production

Carbon neutral synthetic fuels production using concentrated solar thermal energy at nearly 1500 °C temperature is feasible technically and viable commercially in near future with declining costs of CSP plants. Also carbon neutral hydrogen can be produced with solar thermal energy (CSP) using
Sulfur–iodine cycle The sulfur–iodine cycle (S–I cycle) is a three-step thermochemical cycle used to produce hydrogen. The S–I cycle consists of three chemical reactions whose net reactant is water and whose net products are hydrogen and oxygen. All other che ...
,
Hybrid sulfur cycle The hybrid sulfur cycle (HyS) is a two-step water-splitting process intended to be used for hydrogen production. Based on sulfur oxidation and reduction, it is classified as a hybrid thermochemical cycle because it uses an electrochemical Elect ...
,
Iron oxide cycle For chemical reactions, the iron oxide cycle (Fe3O4/FeO) is the original two-step thermochemical cycle proposed for use for hydrogen production. It is based on the reduction and subsequent oxidation of iron ions, particularly the reduction and oxid ...
,
Copper–chlorine cycle The copper–chlorine cycle (Cu–Cl cycle) is a four-step thermochemical cycle for the production of hydrogen. The Cu–Cl cycle is a hybrid process that employs both thermochemical and electrolysis steps. It has a maximum temperature requirement ...
,
Zinc–zinc oxide cycle For chemical reactions, the zinc–zinc oxide cycle or Zn–ZnO cycle is a two step thermochemical cycle based on zinc and zinc oxide for hydrogen production with a typical efficiency around 40%. Process description The thermochemical two-step wat ...
,
Cerium(IV) oxide–cerium(III) oxide cycle The cerium(IV) oxide–cerium(III) oxide cycle or CeO2/Ce2O3 cycle is a two-step thermochemical process that employs cerium(IV) oxide and cerium(III) oxide for hydrogen production. The cerium-based cycle allows the separation of H2 and O2 in two s ...
, etc.


Deployment around the world

A early plant operated in Sicily at
Adrano Adrano (, scn, Ddirnò), ancient ''Adranon'', is a town and in the Metropolitan City of Catania on the east coast of Sicily. It is situated around northwest of Catania, which was also the capital of the province to which Adrano belonged, no ...
. The US deployment of CSP plants started by 1984 with the
SEGS Solar Energy Generating Systems (SEGS) is a concentrated solar power plant in California, United States. With the combined capacity from three separate locations at 354 megawatt (MW), it was once the world's second largest solar thermal energy g ...
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. In 2013, worldwide installed capacity increased by 36% or nearly 0.9
gigawatt The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3. It is used to quantify the rate of energy transfer. The watt is named after James Wat ...
(GW) to more than 3.4 GW.
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
and the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
remained the global leaders, while the number of countries with installed CSP were growing but the rapid decrease in price of PV solar, policy changes and the global financial crisis stopped most development in these countries. 2014 was the best year for CSP but was followed by a rapid decline with only one major plant completed in the world in 2016. There is a notable trend towards developing countries and regions with high solar radiation with several large plants under construction in 2017.


Efficiency

The efficiency of a concentrating solar power system will depend 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 conversion efficiency of 23-35% for "power tower" type systems, operating at temperatures from 250 to 565 °C, with the higher efficiency number assuming a combined cycle turbine. Dish Stirling systems, operating at temperatures of 550-750 °C, claim an efficiency of about 30%.International Renewable Energy Agency, "Table 2.1: Comparison of different CSP Technologies", i
Concentrating Solar Power, Volume 1: Power Sector
RENEWABLE ENERGY TECHNOLOGIES: COST ANALYSIS SERIES, June 2012, p. 10. Retrieved 23 May 2019.
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.


Theory

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 The laws of thermodynamics are a set of scientific laws which define a group of physical quantities, such as temperature, energy, and entropy, that characterize thermodynamic systems in thermodynamic equilibrium. The laws also use various paramet ...
. Real-world systems do not achieve the Carnot efficiency. The conversion efficiency \eta of the incident solar radiation into mechanical work depends on the
thermal radiation Thermal radiation is electromagnetic radiation generated by the thermal motion of particles in matter. Thermal radiation is generated when heat from the movement of charges in the material (electrons and protons in common forms of matter) is ...
properties of the solar receiver and on the heat engine (''e.g.'' steam turbine).
Solar irradiation Solar irradiance is the power per unit area ( surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre ( ...
is first converted into heat by the solar receiver with the efficiency \eta_ and subsequently the heat is converted into mechanical energy by the heat engine with the efficiency \eta_, using Carnot's principle. 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: :\eta = \eta_\mathrm\cdot\eta_\mathrm \cdot \eta_\mathrm \cdot \eta_\mathrm where \eta_\mathrm represents the fraction of incident light concentrated onto the receiver, \eta_\mathrm the fraction of light incident on the receiver that is converted into heat energy, \eta_\mathrm the efficiency of conversion of heat energy into mechanical energy, and \eta_\mathrm the efficiency of converting the mechanical energy into electrical power. \eta_\mathrm is: :\eta_\mathrm = \frac ::with Q_\mathrm, Q_\mathrm, Q_\mathrm respectively the incoming
solar flux Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...
and the fluxes absorbed and lost by the system solar receiver. The conversion efficiency \eta_\mathrm is at most the Carnot efficiency, which is determined by the temperature of the receiver T_H and the temperature of the heat rejection ("heat sink temperature") T^0, : \eta_\mathrm = 1 - \frac The real-world 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 I (e.g. I = 1000\, \mathrm) concentrated C times with an efficiency \eta_ on the system solar receiver with a collecting area A and an absorptivity \alpha: :Q_\mathrm = I C A , :Q_\mathrm = \eta_\mathrm \alpha Q_\mathrm , 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 The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation. Thermal radiation is electromagnetic radiation that most commonly includes both visible radiation (light) and infrared radiation, which is n ...
\epsilon applying the
Stefan–Boltzmann law The Stefan–Boltzmann law describes the power radiated from a black body in terms of its temperature. Specifically, the Stefan–Boltzmann law states that the total energy radiated per unit surface area of a black body across all wavelengths ...
yields: :Q_\mathrm = A \epsilon \sigma T_H^4 Simplifying these equations by considering perfect optics (\eta_\mathrm = 1) and without considering the ultimate conversion step into electricity by a generator, collecting and reradiating areas equal and maximum absorptivity and emissivity (\alpha = 1, \epsilon = 1) then substituting in the first equation gives :\eta = \left(1 - \frac \right) \cdot \left( 1 - \frac \right) 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 (Qlost) 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), Tmax is: T_\mathrm = \left( \right)^ There is a temperature Topt for which the efficiency is maximum, ''i.e.''. when the efficiency derivative relative to the receiver temperature is null: :\frac(T_\mathrm) = 0 Consequently, this leads us to the following equation: :T_^5-(0.75T^0)T_\mathrm^4-\frac = 0 Solving this equation numerically allows us to obtain the optimum process temperature according to the solar concentration ratio C (red curve on the figure below) 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.


Cost and Value

Few CSP plants in China have reached a tariff of US$ 50 per MWh in the year 2021. As early as 2011, the rapid decline of the price of
photovoltaic system A photovoltaic system, also PV system or solar power system, is an electric power system designed to supply usable solar power by means of photovoltaics. It consists of an arrangement of several components, including solar panels to absorb and co ...
s lead to projections that CSP will no longer be economically viable.Google cans concentrated solar power project
''Reve'', 24 Nov 2011. Accessed: 25 Nov 2011.
As of 2020, the least expensive utility-scale concentrated solar power stations in the United States and worldwide are five times more expensive than utility-scale
photovoltaic power station A photovoltaic power station, also known as a solar park, solar farm, or solar power plant, is a large-scale grid-connected photovoltaic power system (PV system) designed for the supply of merchant power. They are different from most building- ...
s, with a projected minimum price of 7 cents per kilowatt-hour for the most advanced CSP stations against record lows of 1.32 cents per kWh for utility-scale PV. This five-fold price difference has been maintained since 2018. Even though overall deployment of CSP remains limited the levelized cost of power from commercial scale plants has decreased significantly in recent years. With a learning rate estimated at around 20% cost reduction of every doubling in capacity the cost 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: CSP deployment has slowed down considerably as most of the above-mentioned markets have cancelled their support, as the technology turned out to be more expensive on a per kWH basis than solar PV and wind power. CSP in combination with
Thermal Energy Storage Thermal energy storage (TES) is achieved with widely different technologies. Depending on the specific technology, it allows excess thermal energy to be stored and used hours, days, months later, at scales ranging from the individual process, ...
(TES) is expected by some to remain cheaper than PV with lithium batteries for storage durations above 4 hours per day, while
NREL The National Renewable Energy Laboratory (NREL) in the US specializes in the research and development of renewable energy, energy efficiency, energy systems integration, and sustainable transportation. NREL is a federally funded research and d ...
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.


Incentives and Markets


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. The initial requirements for plants in the FiT were: * Systems registered in the register of systems prior to 29 September 2008: 50 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). Because of cost concerns Spain has halted acceptance of new projects for the feed-in-tariff on 27 January 2012 Already accepted projects were affected by a 6% "solar-tax" on feed-in-tariffs, effectively reducing the feed-in-tariff. In this context, the Spanish Government enacted the Royal Decree-Law 9/2013 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. This new retroactive legal-economic framework applied to all the renewable energy systems was developed in 2014 by the RD 413/2014, 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 the intention of adding 5GW of CSP capacity between 2021 and 2030. Towards this end bi-annual auctions of 200 MW of CSP capacity starting in October 2022 are expected, but details are not yet known.


Australia

Several CSP dishes have been set up in remote Aboriginal settlements in the
Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an states and territories of Australia, Australian territory in the central and central northern regions of Australia. The Northern Territory ...
:
Hermannsburg Hermannsburg is a village and a former municipality in the Celle district, in Lower Saxony, Germany. Since 1 January 2015 it is part of the municipality Südheide. It has been a state-recognised resort town since 1971. It is situated on the river ...
,
Yuendumu Yuendumu is a town in the Northern Territory of Australia, northwest of Alice Springs on the Tanami Road, within the Central Desert Region local government area. It ranks as one of the larger remote communities in central Australia, and has a t ...
and
Lajamanu Lajamanu, formerly known as Hooker Creek Native Settlement or just Hooker Creek, is a small town of the Northern Territory of Australia. It is located around from Katherine and approximately from Darwin. At the 2016 Australian census, Lajama ...
. So far no commercial scale CSP project has been commissioned in Australia, but several projects were suggested. In 2017 now bankrupt American CSP developer
SolarReserve SolarReserve was a developer of utility-scale solar power projects which include Concentrated Solar Power (CSP) and Photovoltaic (PV) technology. The company has commercialized solar thermal energy storage technology that enables solar power tow ...
got awarded a
PPA PPA may refer to: Biomedical * ''Palpatio per anum'', Latin medical term for a rectal examination * Parahippocampal place area located within the parahippocampal gyrus * Phenylpropanolamine * Primary progressive aphasia Organizations * Pakistan ...
to realize the 150MW
Aurora Solar Thermal Power Project Aurora Solar Thermal Power Project was a planned solar power tower solar thermal power plant to be located north of Port Augusta in South Australia. It was planned to generate 150 MW of electricity after it was completed in 2020. Storage ca ...
in South Australia at a record low rate of just AUD$0.08/kWh or close to USD$0.06/kWh. Unfortunately the company failed to secure financing and the project got 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 is looking to start construction of a 50MW combines CSP and PV facility in Mt. Isa of North-West Queensland in 2021. 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. At State level,
renewable energy Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most 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 PV (photovoltaic) 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

Of late China has been aggressive in developing CSP technology to compete with other electricity generation methods based on renewable and non-renewable energy sources. In the current 14th Five-Year Plan CSP projects are developed in several provinces along side large GW sized solar PV and wind projects. 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 Plan, with the intention of building up an internationally competitive CSP industry. Since the first plants were completed in 2018, the generated electricity from the plants with thermal storage is supported with an administratively set FiT of
RMB The renminbi (; symbol: ¥; ISO code: CNY; abbreviation: RMB) is the official currency of the People's Republic of China and one of the world's most traded currencies, ranking as the fifth most traded currency in the world as of April 2022. ...
1.5 per kWh. At the end of 2020, China operated a total of 545 MW in 12 CSP plants, seven plants (320 MW) are molten-salt towers; another two plants (150MW) use the proven Eurotrough 150 parabolic trough design, three plants (75 MW) use liner 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 Plan is unknown. Federal support projects from the demonstration batch ran out at the end of 2021.


India

In March 2020, SECI called for 5000 MW tenders which can be combination of Solar PV, Solar thermal with storage and Coal based power (minimum 51% from renewable sources) to supply round the clock power at minimum 80% yearly availability.


Future

A study done by
Greenpeace International Greenpeace is an independent global campaigning network, founded in Canada in 1971 by Irving Stowe and Dorothy Stowe, immigrant environmental activists from the United States. Greenpeace states its goal is to "ensure the ability of the Earth t ...
, the European Solar Thermal Electricity Association, and the
International Energy Agency The International Energy Agency (IEA) is a Paris-based autonomous intergovernmental organisation, established in 1974, that provides policy recommendations, analysis and data on the entire global energy sector, with a recent focus on curbing carb ...
's
SolarPACES {, class="infobox" border="1" cellpadding="4" style="float: right; margin: 0 0 1em 1em; width: 20em; border-collapse: collapse; font-size: 90%; clear: right" , - !SolarPACES member countries , - , ; ; ; ; ; ; ; ; ; ; ; ; ...
group investigated the potential and future of concentrated solar power. The study found that concentrated solar power could account for up to 25% of the world's energy needs by 2050. The increase in investment would be from €2 billion worldwide to €92.5 billion in that time period.Concentrated solar power could generate 'quarter of world's energy'
''Guardian''
Spain is the leader in concentrated solar power technology, with more than 50 government-approved projects in the works. Also, it exports its technology, further increasing the technology's stake in energy worldwide. Because the technology works best with areas of high
insolation Solar irradiance is the power per unit area (surface power density) received from the Sun in the form of electromagnetic radiation in the wavelength range of the measuring instrument. Solar irradiance is measured in watts per square metre (W/m ...
(solar radiation), experts predict the biggest growth in places like Africa, Mexico, and the southwest United States. It indicates that the thermal storage systems based in
nitrates Nitrate is a polyatomic ion with the chemical formula . Salts containing this ion are called nitrates. Nitrates are common components of fertilizers and explosives. Almost all inorganic nitrates are soluble in water. An example of an insoluble ...
(
calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to ...
,
potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...
,
sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable iso ...
,...) will make the CSP plants more and more profitable. The study examined three different outcomes for this technology: no increases in CSP technology, investment continuing as it has been in Spain and the US, and finally the true potential of CSP without any barriers on its growth. The findings of the third part are shown in the table below: Finally, the study acknowledged how technology for CSP was improving and how this would result in a drastic price decrease by 2050. It predicted a drop from the current range of €0.23–0.15/kWh to €0.14–0.10/kWh. The European Union looked into developing a €400 billion (US$774 billion) network of solar power plants based in the Sahara region using CSP technology to be known as Desertec, to create "a new carbon-free network linking Europe, the Middle East and North Africa". The plan was backed mainly by German industrialists and predicted production of 15% of Europe's power by 2050.
Morocco Morocco (),, ) officially the Kingdom of Morocco, is the westernmost country in the Maghreb region of North Africa. It overlooks the Mediterranean Sea to the north and the Atlantic Ocean to the west, and has land borders with Algeria to ...
was a major partner in Desertec and as it has barely 1% of the electricity consumption of the EU, it could produce more than enough energy for the entire country with a large energy surplus to deliver to Europe.Tom Pfeiffer (23 August 2009
Europe's Saharan power plan: miracle or mirage?
''Reuters''
Algeria ) , image_map = Algeria (centered orthographic projection).svg , map_caption = , image_map2 = , capital = Algiers , coordinates = , largest_city = capital , relig ...
has the biggest area of desert, and private Algerian firm
Cevital Cevital () is the largest private conglomerate (company), conglomerate in Algeria, with interests in the agri-food sector, retail, industry and services, created by Issad Rebrab. The company's headquarters are in Kouba, Algeria, Kouba, Algeri ...
signed up for Desertec. With its wide desert (the highest CSP potential in the Mediterranean and Middle East regions ~ about 170 TWh/year) and its strategic geographical location near Europe, Algeria is one of the key countries to ensure the success of Desertec project. Moreover, with the abundant natural-gas reserve in the Algerian desert, this will strengthen the technical potential of Algeria in acquiring Solar-Gas Hybrid Power Plants for 24-hour electricity generation. Most of the participants pulled out of the effort at the end of 2014. Experience with first-of-a-kind CSP plants in the USA was mixed. Solana in Arizona, and Ivanpah in California indicate large production shortfalls in electricity generation between 25% and 40% in the first years of operation. Producers blame clouds and stormy weather, but critics seem to think there are technological issues. These problems are causing utilities to pay inflated prices for wholesale electricity, and threaten the long-term viability of the technology. As photovoltaic costs continue to plummet, many think CSP has a limited future in utility-scale electricity production. In other countries especially Spain and South Africa CSP plants have met their designed parameters CSP has other uses than electricity. Researchers are investigating solar thermal reactors 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 H2O, to create hydrogen (H2) from solar energy with no carbon emissions. By splitting both H2O and CO2, 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.


Very large 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. They include the Euro-Mediterranean Desertec proposal and Project Helios in Greece (10 GW), both now canceled. A 2003 study concluded that the world could generate 2,357,840 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 TWh/year (in 2003). The gigawatt size projects would have been arrays of standard-sized single plants. In 2012, the
BLM BLM most commonly refers to: * Black Lives Matter, an international anti-racism movement and organization * Bureau of Land Management, a U.S. federal government agency BLM may also refer to: Organizations * BLM (law firm), United Kingdom and ...
made available of land in the
southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, Ne ...
for solar projects, enough for between 10,000 and 20,000 GW. The largest single plant in operation is the 510 MW Noor Solar Power Station. In 2022 the 700 MW CSP 4th phase of the 5GW
Mohammed bin Rashid Al Maktoum Solar Park Mohammed bin Rashid Al Maktoum Solar Park is a solar park spread over a total area of 77 km2 in Saih Al-Dahal, about 50 kilometers south of the city of Dubai. It is one of the world's largest renewable projects based on an independent powe ...
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 The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...
. These locations have a higher potential for CSP than areas with less sun. Abandoned
opencast mine Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow. This form of mining ...
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.


Environmental effects

CSP has a number of environmental effects, particularly on water use, land use and the use of hazardous materials. 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.


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. 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 for power tower plants and for trough plants. This was higher than the operational water consumption (with cooling towers) for nuclear at , coal at , or natural gas at . A 2011 study by the National Renewable Energy Laboratory came to similar conclusions: for power plants with cooling towers, water consumption during operations was for CSP trough, for CSP tower, for coal, for nuclear, and for natural gas. The Solar Energy Industries Association noted that the Nevada Solar One trough CSP plant consumes . 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. 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 Barstow is a city in San Bernardino County, California, in the Mojave Desert of Southern California. Located in the Inland Empire region of California, the population was 25,415 at the 2020 census. Barstow is an important crossroads for the I ...
, and the Genesis Solar Energy Project in
Riverside County, California Riverside County is a County (United States), county located in the southern California, southern portion of the U.S. state of California. As of the 2020 United States Census, 2020 census, the population was 2,418,185, making it the fourth-most ...
. 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 , but only (less than one percent) is lost through evaporation. Since the 1970s, the majority of US power plants have used recirculating systems such as cooling towers rather than once-through systems.


Effects on wildlife

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 raptors who hunt the birds. Federal wildlife officials were quoted by opponents as calling the Ivanpah power towers "mega traps" for wildlife. 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. Some of the claims may have been overstated or exaggerated. According to rigorous reporting, in over six months, 133 singed birds were counted at Ivanpah. By focusing no more than four mirrors on any one place in the air during standby, at
Crescent Dunes Solar Energy Project The Crescent Dunes Solar Energy Project is a solar thermal power project with an installed capacity of 110 megawatt (MW) and 1.1 gigawatt-hours of energy storage located near Tonopah, about northwest of Las Vegas. Crescent Dunes is the fir ...
, in three months, the death rate dropped to zero.


See also

* Dover Sun House *
Concentrator photovoltaics Concentrator photovoltaics (CPV) (also known as concentration photovoltaics) is a photovoltaic technology that generates electricity from sunlight. Unlike conventional photovoltaic systems, it uses lenses or curved mirrors to focus sunlight onto ...
(CPV) *
Daylighting Daylighting is the practice of placing windows, skylights, other openings, and Reflective surfaces (climate engineering), reflective surfaces so that sunlight (direct or indirect) can provide effective internal lighting. Particular attention is ...
*
List of solar thermal power stations This is a list of the largest facilities generating electricity through the use of solar thermal power, specifically concentrated solar power. Operational Under construction Announced Cancelled Decommissioned * Eurelios p ...
*
Luminescent solar concentrator A luminescent solar concentrator (LSC) is a device for concentrating radiation, Non-ionizing radiation, solar radiation in particular, to produce electricity. Luminescent solar concentrators operate on the principle of collecting radiation over a ...
*
Salt evaporation pond A salt evaporation pond is a shallow artificial salt pan designed to extract salts from sea water or other brines. The Salt pans are shallow and large of size because it will be easier for sunlight to travel and reach the sea water. Natural sal ...
*
Solar air conditioning Solar air conditioning, or "solar-powered air conditioning", refers to any air conditioning (cooling) system that uses solar power. This can be done through passive solar design, solar thermal energy conversion, and photovoltaic conversion (sunli ...
*
Solar thermal energy Solar thermal energy (STE) is a form of energy and a technology for harnessing solar energy to generate thermal energy for use in industry, and in the residential and commercial sectors. Solar thermal collectors are classified by the United St ...
*
Solar thermal collector A solar thermal collector collects heat by absorbing sunlight. The term "solar collector" commonly refers to a device for solar hot water heating, but may refer to large power generating installations such as solar parabolic troughs and sola ...
*
Solar water heating Solar water heating (SWH) is heating water by sunlight, using a solar thermal collector. A variety of configurations are available at varying cost to provide solutions in different climates and latitudes. SWHs are widely used for residential a ...
*
Thermal energy storage Thermal energy storage (TES) is achieved with widely different technologies. Depending on the specific technology, it allows excess thermal energy to be stored and used hours, days, months later, at scales ranging from the individual process, ...
*
Thermochemical cycle Thermochemical cycles combine solely heat sources (''thermo'') with ''chemical'' reactions to split water into its hydrogen and oxygen components. The term ''cycle'' is used because aside of water, hydrogen and oxygen, the chemical compounds used in ...


References


External links


Concentrating Solar Power Utility

NREL Concentrating Solar Power Program

Plataforma Solar de Almeria, CSP research center

ISFOC (Institute of Concentrating Photovoltaic Systems)
* {{Authority control * Solar architecture Solar power Solar power stations French inventions