Electric Energy Production

An aerial view of the PS10 and PS20 central tower solar power plants near Seville, Spain.

In most concentrating solar power plants, concentrated solar radiation is used to produce thermal energy at temperatures of several hundred degrees Celsius. This energy is then used to generate steam, which drives a turbine in a conventional Rankine cycle. In some systems, a heat-transfer fluid transfers the collected heat to water in a heat exchanger, while others generate steam directly in the solar receiver. This system requires cooling, which can be difficult to provide in desert regions. Wet-cooled parabolic trough power plants typically consume around 3,000 litres of water per MWh of electricity generated. Dry cooling can greatly reduce this consumption, although at the cost of somewhat lower efficiency. Parabolic dish systems are generally air-cooled.

Some concentrating solar power plants are equipped with thermal energy storage, allowing surplus heat collected during periods of high solar irradiation to be stored for later use. The storage medium can be solid material, thermal oil or, most commonly, molten salts. The stored heat can be used to generate electricity after sunset or during periods of reduced solar radiation, making the power output less dependent on instantaneous sunlight than that of photovoltaic systems. A central tower solar power plant without thermal energy storage may have an annual capacity factor of around 25%, while plants with large thermal storage systems can achieve around 65% or more.

Some concentrating solar power plants are designed as hybrid systems in which natural gas or biomass can provide additional heat when insufficient solar energy is available. Other plants rely solely on solar energy combined with thermal energy storage.

Depending on grid requirements, CSP plants with thermal energy storage can be operated in several ways:

The output of solar photovoltaic power plants is strongly dependent on the intensity of sunlight.

• A power plant has little or no thermal energy storage and generates electricity mainly when the Sun is shining.
• A power plant has a large thermal energy storage system and a medium-output turbine. Part of the collected heat is stored during the day, allowing electricity generation to continue for several hours after sunset and to be shifted towards periods of higher demand.
• A power plant has a large thermal energy storage system and a relatively low-output turbine, allowing it to generate electricity continuously for extended periods.
• A power plant has a large thermal energy storage system and a high-output turbine, allowing stored energy to be used to generate high power during periods of peak demand.

Solar Power Plants On-line interactive 3D model

The Largest Concentrating Solar Power Plants in the World

The table lists some of the world’s largest operating concentrating solar power plants and complexes by installed CSP capacity. Photovoltaic capacity in hybrid solar projects is not included.

* Scheduled for closure in 2026

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4 pictures