The Andasol 3 solar-thermal power plant is located in the province of Granada in southern Spain. It was built by innogy and the municipal utility of Munich in collaboration with Ferrostaal, RheinEnergie and Solar Millennium.
The power plant has an installed capacity of around 50 megawatts and is jointly operated by the project partners. The neighbouring projects Andasol 1 and Andasol 2, each with around 50 megawatts of capacity, are already in operation. Almost identical in their construction, the power plants have a total collector surface of over 1.5 million square metres – equivalent to an area of 210 football fields.
Solar power around the clock
205,000 parabolic reflectors gather sunlight at the Andasol 3 facility. Each parabolic reflector segment measures 12 times 6 square metres. The thermal energy is transferred to a water/steam cycle via heat exchangers. Like in conventional power plant, this steam drives a turbine. The generator connected to this produces power. A thermal storage facility then allows the energy to be made available when it’s needed. This storage unit holds 30,000 tonnes of a special salt mixture. It has sufficient capacity for over seven hours operation at full load. Andasol 3 can thus provide a reliable supply of energy even after the sun has set. The power plant generates around 165 million kilowatt hours of power each year.
How a solar power plant works
If you’ve ever used a magnifying glass to concentrate the sun’s rays you’ll be familiar with the effect: enough heat is generated to set a piece of paper alight. Parabolic trough power plants such as Andasol 3 use the same effect. They concentrate the sun’s rays by using huge concave mirrors. These parabolic mirrors direct the sunrays onto an absorber pipe called a receiver. The thermal oil that flows through this vacuum-insulated pipe is then heated by the concentrated solar energy to up to 400 degrees. The hot thermal oil converts the water to steam in a heat exchanger – and the steam drives a turbine, just like in a conventional power plant. Finally, the generator connected to the turbine produces power.
What makes solar-thermal power plants such as Andasol 3 special is the heat storage facility. This makes the solar power available even in bad weather conditions and during the night. Liquid salt serves as the storage medium, balancing out fluctuations in production and ensuring power supply can continue after sunset. When the sun is shining, the salt is heated and poured into the storage tank. When it’s cloudy or at night, the hot salt releases its energy to the thermal oil. In order to guarantee capacity of over seven hours of full load operation, 28,500 tonnes of a special salt mixture are required. This enables the plants to produce almost twice as much power as a solar power plant without a storage unit.
Who is involved in Andasol 3?
The Andasol 3 solar-thermal power plant is operated by project company Marquesado Solar S.L. The municipal utility of Munich holds 48.9 percent of this company. innogy and RheinEnergie hold 25.1 percent via a joint holding company (Andasol AS 3 Beteiligungs GmbH: innogy: 51 percent, RheinEnergie: 49 percent). The remaining 26 percent of the project company is held in equal shares by Ferrostaal Industrial Projects GmbH and Andasol 3 Kraftwerks GmbH.
Andasol 3 solar-thermal plant at a glance
|Location||Around 10 km south east of Guadix in the province of Granada|
Area of solar field:
|Number of mirrors:||204,288|
|Dimensions of the parabolic mirror segments used:||Length: around 12 m, width: around 6 m|
|Number of receivers (absorber pipes):||21,888 pipes, each 4 m long|
|Storage capacity of heat storage unit:||28,500 t of salt over 7 hours at full load|
|Power plant capacity|
|around 50 MW|
|Annual operating hours:||3,700 hours at full load|
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