Solar Power Plant Operates At Night

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In southern Spain, the Gemsolar solar plant opened earlier this month and is expected to provide residents with 20 megawatts of power – enough to supply over 6,000 homes. However, the plant’s output generation isn’t what makes it stellar but rather how it generates that electricity.

Solar power without sunlight
When most people think of a solar plant, we envision acres upon acres of solar panels that work hard from dawn to dusk, harvesting the sun’s rays and turning them into electricity. While Gemsolar’s plant sprawls across the Spanish landscape, it doesn’t shut off when the sun goes down. This is due to the fact that Gemsolar doesn’t use photovoltaic solar panels. Instead they use heliostatics – leveraging heat energy from sunlight to create electricity.

How it works
Gemsolar’s plant consists of 2,650 mirrors used to redirect sunlight to a centrally located tower containing salt tanks.  Heat from the sun is concentrated to 1652oF and used to melt the salt, a combination of sodium nitrate and potassium nitrate, in the tower. The heat is then transferred to a pool of water surrounding the tower to generate steam. Steam from the water turns a turbine and generates electricity. The absorbed heat can stay in the melted salt for up to 15 hours, which allows the plant to continue operating long after the sun goes down.

The solar plant started operations earlier this year and is expected to hit 70% output capacity by 2012.