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Credit: Reuben Wu © 2016

Electricity Generation

Concentrated Solar

The Crescent Dunes Solar Energy Project is a 110-megawatt solar thermal plant located near Tonopah, Nevada. It also is a molten salt storage plant, capable of holding 1.1 billion kilowatt-hours of energy. 10,347 heliostats circle a 640-foot tower at the center and have a combined surface area of 1.28 million square feet. The $1 billion plant produces electricity at 13.5 cents per kilowatt-hour, higher than wind and solar farms to be sure. However, Tonopah provides steady baseload power, which in turn enables intermittent energy from renewable wind and solar to be seamlessly integrated into the grid.

Concentrated solar power (CSP), also known as solar thermal electricity, has been around since the 1980s. Instead of converting sunlight directly into electricity like photovoltaics (PV) do, it relies on the core technology of fossil-fuel generation: steam turbines. The difference is that rather than using coal or natural gas, CSP uses solar radiation as its primary fuel—free and clear of carbon.

Mirrors, the essential component of any CSP plant, are curved or angled in specific ways to concentrate incoming solar rays to heat a fluid, produce steam, and turn turbines. Because CSP relies on immense amounts of direct sunshine, it is best suited to hot, dry regions where skies are clear.

A critical advantage of CSP is energy storage. Unlike PV panels and wind turbines, CSP makes heat before it makes electricity, and heat is easier to store. When equipped with molten salt tanks for heat storage, CSP plants can continue to produce electricity well after the sun goes down.

As of 2014, CSP was limited to just 4 gigawatts worldwide. As the technology becomes more effective and less expensive, the central benefit of reliability will hasten its growth.


“tale of two countries, Spain vs. the U.S.”: IEA. Technology Roadmap: Solar Thermal Electricity. Paris: International Energy Agency, 2014.

California in the 1980s: Perlin, John. Let It Shine: The 6,000-Year Story of Solar Energy. Novato, California: New World Library, 2013.

2014…4 gigawatts worldwide: IEA. Solar Thermal.

[generation] in Spain: IEA. Solar Thermal.

Morocco…Noor Ouarzazate Solar Complex: Nelsen, Arthur. “Morocco to Switch on First Phase of World's Largest Solar Plant.” The Guardian. February 4, 2016; Hicks, Celeste. “Morocco Lights the Way for Africa on Renewable Energy.” The Guardian. November 17, 2016.

direct normal irradiance…latitudes: IEA. Solar Thermal.

Optimal locales [for CSP]: IEA-ETSAP and IRENA. Concentrating Solar Power—Technology Brief. Paris and Abu Dhabi: International Energy Agency Energy Technology Systems Analysis Programme and International Renewable Energy Agency, 2013.

Mediterranean basin…Kalahari Desert…potential: Pfenninger, Stefan, et al. “Potential for Concentrating Solar Power to Provide Baseload and Dispatchable Power.” Nature Climate Change, 4, no. 8 (2014): 689-692.

heat can be stored…more cheaply: Romm, Joe. “Why You Should Be Paying Attention to the ‘Other’ Form of Solar Power.” Think Progress. June 10, 2015.

Efficiency of…[t]echnologies…under development: Barbee, Jeffrey. “Could This Be the World’s Most Efficient Solar Electricity System?” The Guardian. May 13, 2015.

Solar Reserve…strategy to stop bird deaths: Kraemer, Susan. “One Weird Trick Prevents Bird Deaths at Solar Towers.” Clean Technica. April 16, 2015.

[History of using] mirrors to start fires: Perlin, Shine.

view all book references

Technical Summary

Concentrated Solar

Project Drawdown defines concentrated solar as: an electricity generation technology that uses heat provided by direct normal solar irradiance concentrated on a small area, with and without storage. This solution replaces conventional electricity-generating technologies such as coal, oil, and natural gas power plants.

Presently, there are four main concentrated solar power (CSP) technologies competing for the market: 1) Parabolic Trough Collectors; 2) Parabolic Dish Collectors; 3) Heliostat Field Collectors (Tower); and 4) Linear Fresnel Reflectors. Though the Parabolic Trough is the oldest and has the most widespread use, the newest (Tower) is the most likely to succeed, since it is the most economically viable technology that incorporates storage—increasingly a requirement of CSP. This analysis models all CSP technologies, with and without storage.


Total Addressable Market [1]

The total addressable market for concentrated solar is based on projected global electricity generation in terawatt-hours from 2020-2050, with current adoption [2] estimated at only 0.04 percent of generation (IRENA, 2016).

Concentrated solar is particularly promising in regions with more than 2500 kilowatt-hours per meter squared per year of sunlight radiation, such as in the southwestern United States, Central and South America, Northern and Southern Africa, the Mediterranean countries of Europe, the Near and Middle East, Iran, and the desert plains of India, Pakistan, the former Soviet Union, China, and Australia (ESTELA, 2016). This regional potential is accounted within the external sources projections.

Adoption Scenarios [3]

Impacts of increased adoption of concentrated solar from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

  • Plausible Scenario: Based on the evaluation of scenarios from seven global energy systems models,[4] the Plausible Scenario follows a low growth trajectory, capturing 4.28 percent of the market share in 2050.
  • Drawdown Scenario: This scenario follows a medium growth trend derived from these same models, representing 8.05 percent of the electricity generation mix in 2050.
  • Optimum Scenario: This scenario projects the most aggressive growth potential and is aligned with the Greenpeace Advanced Energy [R]evolution Scenario,[5] resulting in an 8.29 percent share of the market.

Concentrated solar is particularly promising in regions with more than 2500 kilowatt-hours per meter squared per year of sunlight radiation, such as in the southwestern United States, Central and South America, Northern and Southern Africa, the Mediterranean countries of Europe, the Near and Middle East, Iran, and the desert plains of India, Pakistan, the former Soviet Union, China, and Australia (ESTELA, 2016). This regional potential is accounted within the external sources projections.

Financial Model

The financial inputs used in the model assume an average installation cost of US$6,603 per kilowatt[6] (IPCC, 2014; IRENA, 2016; REN21, 2016; Lazard, 2016) with a learning rate of 14.6 percent (Hayward and Graham, 2013), reducing the cost to US$3,780 per kilowatt in 2030 and to US$2,372 in 2050. An average capacity factor of 47 percent is used for concentrated solar, compared to 55 percent for conventional technologies such as coal, natural gas, and oil power plants. Variable operation and maintenance costs of US$0.033 per kilowatt-hour and fixed costs of US$96.2 per kilowatt are considered for CSP, compared to US$0.005 and US$33.0, respectively, for the conventional technologies.

Integration [7]

Through the process of integrating concentrated solar with other solutions, the total addressable market for electricity generation technologies was adjusted to account for reduced demand resulting from the growth of more energy-efficient technologies,[8] as well as increased electrification from other solutions like electric vehicles and high-speed rail. Grid emissions factors were calculated based on the annual mix of different electricity-generating technologies over time. Emissions factors for each technology were determined through a meta-analysis of multiple sources, accounting for direct and indirect emissions.


The results for the Plausible Scenario show that the net cost compared to the Reference Scenario would be US$1,319.7 billion from 2020-2050, with nearly US$413.85 billion in savings over the same period. Increasing the use of concentrated solar from about 0.04 percent in 2014 to 4.3 percent of world electricity generation by 2050 would require an estimated US$2.2 trillion in cumulative first costs. With its low greenhouse gas emissions, under the Plausible Scenario, CSP could reduce 10.9 gigatons of carbon dioxide-equivalent greenhouse gas emissions from 2020-2050.

Both the Drawdown and Optimum Scenarios are more ambitious in the growth of CSP technologies, with impacts on greenhouse gas emission reductions over 2020-2050 of 26 gigatons and 22.4 gigatons carbon dioxide-equivalent, respectively, for both scenarios.



The results of the Plausible Scenario are more conservative than those of the 2°C Scenario of IEA ETP (2016), which estimates the growth of CSP to reach 6.7 percent of the market. Compared to the Greenpeace Energy [R]evolution Scenario (Greenpeace, 2016), our results are also significantly less ambitious.


Despite still being in its infancy, concentrated solar has significant potential for helping reverse global warming in an affordable way. However, the competition and growth of other more mature and less expensive renewable energy sources, such as onshore wind and solar photovoltaic, might delay the short-term adoption of CSP. The main advantages of CSP with storage is the possibility of providing firm and dispatchable power. Nevertheless, when compared to other solar technologies, CSP is heavily dependent on location, due to the size of the projects and the irradiance radiation needed.

The amount of new concentrated solar power capacity is projected to continue growing, but its pace is dependent on policy support schemes, either through stringent greenhouse gas mitigation policies or through financial and regulatory mechanisms for its adoption. Cost reductions will be driven by increasing economies of scale, more competitive supply chains, and technology improvements that will raise capacity factors and/or reduce installation costs.

[1] For more about the Total Addressable Market for the Energy Sector, click the Sector Summary: Energy link below.

[2] Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.

[3] To learn more about Project Drawdown’s three growth scenarios, click the Scenarios link below. For information on Energy Sector-specific scenarios, click the Sector Summary: Energy link.

[4] GEM-E3 450 scenario, MESSAGE-Macro 450 scenario, IMAGE-Timer 450 scenario (AMPERE, 2014); IEA ETP 2°C Scenario (2016); Greenpeace Energy [R]evolution Scenario (2015); Advanced Scenario from the Greenpeace Solar Thermal Electricity Global Outlook 2016 (Greenpeace et al., 2016).

[5] It represents an ambitious pathway towards a fully decarbonized energy system in 2050, with significant additional efforts compared to the Energy [R]evolution Scenario. The Advanced Energy [R]evolution Scenario needs strong efforts to transform the energy systems of all world regions towards a 100 percent renewable energy supply.

[6] All monetary values are presented in US2014$.

[7] For more on Project Drawdown’s Energy Sector integration model, click the Sector Summary: Energy link below.

[8] For example: LED lighting, heat pumps.

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