Photovoltaic panels convert sunlight directly into electricity. But they aren’t the only way to get electricity from the sun. Concentrating solar power, known as CSP technologies, use arrays of mirrors to reflect and concentrate sunlight onto receivers that collect the energy and convert it to heat. The heat then produces electricity using a steam turbine or heat engine to run a generator.
CSP makes the most sense where there is abundant sunshine. Thus, it is being deployed in places like the deserts in the southwestern United States, in Spain, and in the Middle East.
Economics makes CSP a utility-level technology rather than a distributed technology. One significant advantage it has over photovoltaics is that it is readily combined with storage technology. CSP systems heat up a working fluid – often a molten salt – that can retain its heat long after the sun has set. As a result, CSP plants can operate far longer than photovoltaic plants each day. And with appropriate methods of storing the heated fluid, they can actually dispatch electricity on demand.
There are quite a few CSP plants already in operation around the world, but we are now in the midst of a rapid expansion of the technology. Three huge plants in the U.S. are coming on line over the next year: the Mohave Solar Project near Barstow, California, the Ivanpah Solar Power Facility near Las Vegas, and the Solana Generating Station in Arizona. These three plants alone will provide nearly a gigawatt of electricity.
In deserts around the world, concentrating solar power is heating up.
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Web Links
For information on this technology, please visit:
http://www.eere.energy.gov/basics/renewable_energy/csp.html
Photo, taken on May 13, 2009, courtesy of Alex Lang via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY, with partial support from the Field Day Foundation.