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| Fig. 1: Photograph of the Ivanpah CSP facility in the Mojave Desert, taken from an airplane. (Image Source: N. Lutz) |
To generate most electricity worldwide, steam is used to turn a turbine that is connected to a generator. By pushing against the turbine blades, the steam transforms its thermal energy into mechanical energy of the turbine, which the generator then converts into electrical energy. To make the steam used in this process, a heat source is needed. Traditionally, the heat comes from the combustion of fossil fuels such as coal and natural gas. However, there are other lower carbon heat source options, including concentrating solar power (CSP), in which sunlight is concentrated onto a fluid to heat it. In one of the more common CSP designs, power tower CSP (Fig. 1), surrounding mirrors reflect sunlight to the top of a central tower to heat fluid within it. The fluid, often a molten salt, can then be used to boil water, creating steam that turns a turbine. Alternatively, water can be directly used as the fluid.
Despite both CSP and photovoltaic (PV) solar panels harvesting energy from the sun, the two technologies differ greatly. Solar panels directly convert photon energy from the sun into electricity, while CSP converts sunlight into thermal energy of the working fluid and then into electricity through the process discussed above. The electricity created from solar panels must be used immediately or stored in systems such as pumped hydropower (converted to water potential energy) and batteries (converted to chemical energy) until use. In contrast, CSP allows for energy storage in the form of thermal energy prior to electricity generation, which helps alleviate the issue of solar intermittency.
The International Renewable Energy Agency (IRENA) reported CSP to have a global power capacity of around 6.9 GW in 2023, less than 1% of PV's 2021 global power capacity of 843 GW, reported by BP. [1,2] To put this into perspective, solar PV supplied 3.5% of global electricity in 2021. [2] Clearly, CSP currently contributes little electricity to the grid overall, likely due to its high cost compared to PV and other sources. Average capital costs for PV installed in 2023 were 758 USD per kW, according to IRENA. [3] In contrast, the three CSP plants built globally between 2021 and 2023 cost 9,728 USD/kW (Chile), 4,431 USD/kW (China), and 6,689 USD/kW (United Arab Emirates) to install. [3,4] From these prices, it is clear that the typical installation price of CSP is currently much higher than of solar PV. Furthermore, Khan et al. found that operation and maintenance costs of CSP are 2-4 times higher than PV. [5] Therefore, for CSP to compete with PV and other energy sources on a significant scale, it is imperative that the price of CSP drop drastically.
© Naomi Lutz. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "Renewable Energy Statistics 2024," International Renewable Energy Agency, 2024.
[2] "BP Statistical Review of World Energy," British Petroleum, June 2022.
[3] "Renewable Power Generation Costs in 2023," International Renewable Energy Agency, 2024.
[4] "Renewable Power Ggeneration Costs in 2022," International Renewable Energy Agency, 2023.
[5] M. I. Khan et al., "The Economics of Concentrating Solar Power (CSP): Assessing Cost Competitiveness and Deployment Potential," Renew. Sustain. Energy Rev. 200, 114551 (2024).