Tuesday, February 18, 2014

Who needs sunlight? In Arizona, solar power never sleeps

Ars visits the Solana solar thermal power plant, newly online in October.

That’s why most power suppliers diversify, using electricity from different sources to meet local needs. Solar power is abundant in the middle of sunny, clear days, but energy from other sources—coal, nuclear, or hydroelectric power for example—is necessary at night or when the weather is bad.

But increasingly efficient technology is allowing solar plants to contribute for a longer period of time each day and produce energy even in cloudy conditions. The key is a design that allows them to store the sun’s energy to be used later. And new facilities, such as the Solana power plant that recently came online in Gila Bend, Arizona, are increasing solar energy’s niche by producing electricity several hours after the sun sets.

Decked out in a too-large hard hat, neon yellow vest, and some very trendy safety goggles, Ars recently had the opportunity to visit Solana and find out precisely how these plants power cities after dark. 

A solar primer

Unlike traditional photovoltaic systems, which directly convert the sun’s energy to electricity by liberating electrons, these new plants use “concentrated solar power,” or CSP. As the name suggests, CSP relies on either mirrors or lenses to collect and focus the sun’s heat, which is then used to generate power.

CSP isn’t exactly novel. According to legend, Archimedes used giant hexagonal mirrors to create a “death ray” to set fire to Roman ships, saving the city of Syracuse from invasion more than 2,000 years ago (whether or not this scenario actually happened is hotly debated). In a more recent era, I remember watching my brother perform small-scale mass murder with a magnifying glass, concentrating the sun’s rays onto the delicate bodies of insects.

For the rest of the story: http://arstechnica.com/science/2014/02/making-solar-power-even-after-the-sun-goes-down/

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