Solar Energy Plant Generates Electricity Even When the Sun Goes Down Thanks to Molten Salts
Gemasolar, located in the south of Spain, is the first commercial-scale plant in the world to combine a central tower solar receiver and molten salt heat storage technology. The project is a operated by Torresol Energy, a partnership between Spanish firm SENER and Abu Dhabi renewable energy firm Masdar. The plant which is in operation since 2011 can generate power even when there is no sun, as the collected solar energy is stored in the massive molten salt hot storage tank. The 220 million euro project harnesses the collective power of 2650 heliostats spread out across 185 hectares. Each steel mirror has a surface area of 110 square meters, these mirrors reflect solar radiation towards the giant receiver tower located at the centre of the site. The receiver absorbs roughly 95 percent of the radiation.
This is where the molten salt technology comes into play. The concentrated solar radiation is used to heat and liquefy the cold salts (sodium and potassium nitrates) located in a steel tank, the salts are then pumped to the top of the tower where the temperature shoots up to 565° Celsius. “When heated, the molten salts produce water vapor that runs a steam turbine and produces electricity in a process that is very similar to a conventional thermosolar power plant,” explained Santiago Arias, retired Technical Director at Torresol. This system allows the plant to produce power 24 hours a day, 7 days a week, even when there is no sun. The radiation is stored in the form of the heated salts.