WorldÂ’s First Solar Plant To Generate Electricity Even At Night

Gemasolar Molten Salt CSP concentrates solar energy with a central tower and mirrors in Seville, Spain, using thermal storage to power steam turbines at night, delivering firm, low-carbon electricity and high capacity factors.

The most obvious criticism of solar energy is that it doesn’t work very well when the sun is down. The new Gemasolar heliostatic plant doesn’t have that problem, on account of a vat of molten salt that keeps it running through 15 hours of dark.

More than 2600 concentrically arranged mirrors at the Gemasolar installation just outside of Seville, Spain concentrate solar energy towards a centrally located molten nitrate salt tank. As the rays converge, they super-heat the salt to over 900C, causing water around the tank to boil and drive steam turbines. In addition, any superfluous heat generated during the day is stored within the liquefied salt. It acts like a giant thermal battery for driving the turbines at night and during overcast days — highlighting the future of solar storage — up to 15 hours at a time with no sunlight. Seville, Spain, however, is one of the sunniest areas in Europe, for solar power in Spain projects, so that doesn’t happen very often.

The $US410 million Gemasolar plant just opened and has a potential output of 20 megawatts, and similar in concept to a 50 MW solar thermal plant in Spain now underway, though it is currently operating below that capacity officials expect it could reach 70 per cent capacity by 2012. It’s the largest solar site in Europe of its type, and it has an annual production total or roughly 110 GWh/year — enough to power 25,000 homes and reduce atmospheric CO2 emissions by more than 30,000 tons a year.

The combination of thermal energy storage and sunny weather guarantees that the Gemasolar plant can operate for at least 6500 hours a year, supporting Spain’s plan to add 6,700 green megawatts nationwide by 2012, up to three times longer than other renewable sources.

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