One of the largest solar power plants in the world is the Andasol plant situated on a barren, high-altitude site in the Andalucia region of Spain. The plant provides electricity for up to 500,000 people in the region.
The Andasol plant does not use photovoltaic technology to produce electricity. It is a solar thermal plant. 620,000 curved mirrors focus sunlight onto tubes filled with a synthetic oil and heat the oil to an incredible 750 degrees Fahrenheit. The hot oil is then used to produce steam that drives turbines to generate electricity.
An added feature of the Andasol plant is that some of the energy from the hot oil heats the contents of a tank containing thousands of tons of a molten salt that can retain the heat for many hours. Storing the heat in this way and using it to run the turbines when desired allows the plant to operate for about 7 ½ hours when the sun isn’t shining. This means that cloudy periods during the day don’t have to shut the plant down and the plant usually can keep making electricity long after sundown.
Solar thermal plants like this one only really make sense in places with strong and abundant year-round sunshine. But there are plenty of such places around the globe. The largest solar thermal plants in the world, built in recent years, are in our own southwest deserts. There may end up being many gigawatts of solar thermal plants added to the world’s energy resources over time. Estimates are that with sufficient investment, all forms of solar energy could be the world’s largest energy source by the year 2050.
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Even after dark, vast Spanish solar plant harnesses sun’s power
Photo, posted May 12, 2008, courtesy of Jumanji Solar via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio.