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Flower power (no, not that kind…)

29/10/2010

At three feet (11 meters) tall, the SunCatcher is almost four times bigger than the world’s largest biological flower, the Sumatran titan arum. It has parabolic petals that appear virtually flat, like those of a buttercup. The device is made up of 40 mirrors, tightly arranged into a 3,400-square-foot (315-square-meter) dish that, like a real flower, angles toward the sun.

The SunCatcher is an enormous solar dish made of mirrors and metal, but it’s best thought of as a giant silver flower.

 

At three feet (11 meters) tall, the SunCatcher is almost four times bigger than the world’s largest biological flower, the Sumatran titan arum. It has parabolic petals that appear virtually flat, like those of a buttercup. The device is made up of 40 mirrors, tightly arranged into a 3,400-square-foot (315-square-meter) dish that, like a real flower, angles toward the sun. Unlike flora, however, the SunCatcher utilizes heat rather than light, transforming it into electricity. And there’s very little watering required.


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Arizona-based Stirling Energy Systems makes the SunCatchers, which have shown great promise in the increasingly competitive renewable energy market. South of Phoenix, Arizona, 60 SunCatchers are programmed to rise in the morning and spend the rest of the day following the sun’s rays. The array produces 1.5 megawatts of energy for customers of Salt River Project, a utility company. The system is part of a pilot project meant to prove the technology’s potential as a utility-grade energy source. Stirling engines like the SunCatcher could deliver a big boost to the search for clean, renewable sources of energy.

 

Stirling engines would be perfect power sources for the developing world, except for one problem—the cost. No low-priced Stirling engines exist, nor is there any government interest in funding them. Craig Kinzelman and William Beale discovered this the hard way. Kinzelman produced Stirlings in Bangladesh 20 years ago; when his financial backers dropped out, he set up a joint venture with an Indian company in Madras, producing more than 100 engines before running out of cash.

 

Ericsson not only predicted the importance of solar power; he anticipated how the reliance on fossil fuel could stymie innovation, too.

 

Ericsson devoted tremendous effort to developing a solar-powered engine, but didn’t succeed because of crude solar collectors. He singled out places like the equatorial regions and “lower California,” though, as special solar power hotspots. And in fact, the western U.S. is one of the places where a version of Ericsson’s Stirling-inspired invention is already cranking out energy.


Then there’s the water, an increasingly crucial issue in the driest climates. According to figures from Arizona Department of Water Resources industrial planner Laura Grignano, coal and nuclear plants use 400 to 750 gallons (1,500 to 2,800 liters) per megawatt hour to cool the plants and produce the steam that propels the turbines. Natural gas plants use 200 gallons (750 liters) to produce steam, while other solar systems use 100 to 450 gallons (375 to 1,700 liters) for steam. Stirling dishes sip just 20 gallons (75 liters) per megawatt hour; the only water needed is to clean the silver mirrors. In fact, Tessera Solar’s plant consumes less water than the farmer who previously occupied the land the company leases from Salt River Project.

 

More recently, Stirling’s evolution from an enthusiasts’ hobby to a utility-grade power source has been aided by government funding, new legislation and the imperative to find replacements for fossil fuels. In 2008 and 2009, Irish multinational NTR invested heavily—to the tune of $150 million—in Stirling Energy Systems. Tessera Solar has some heavyweight backing, too, including long-term deals that will give the company time to bring the price of Stirling energy down so it can compete with coal-fired plants. These kinds of investments show that Stirling engines are definitely moving out of the hobbyists’ basements and into the mainstream.

 

The answer may be unfolding right now in the garden of SunCatchers just south of Phoenix, Arizona.

 

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