Hawaiian firm shrinks solar thermal power

It's not as common as solar photovoltaic panels, but Hawaiian start-up Sopogy thinks small-scale solar thermal makes sense. Photos: Concentrating on solar power in Hawaii

Perhaps it's not surprising that balmy Hawaii is home to a company that's pushing the envelope of solar thermal technology.

Start-up Sopogy, based in Honolulu, has taken the basic design of large solar thermal power plants and shrunk it down so it can fit on a building's roof.

Demo models of its electricity-generating solar collectors--essentially metal half-pipes with a reflective coating--are now being tested with a Fortune 500 company and a few utility customers, according to company president and CEO Darren Kimura.

To expand, this fall the venture-funded company intends to raise an additional $9 million, which it hopes to secure by the end of the year, he said.

Concentrating solar power, or CSP, uses reflective troughs or dishes to concentrate sunlight to heat a liquid that flows through a pipe above the troughs. That heated liquid, which can be oil or water, is converted into steam to turn an electric turbine.

On Monday, start-up Ausra announced that it has received $40 million in venture funding to finance product development and construction of a large-scale 175-megawatt solar thermal power plant in California.

That's one of many projects, such as Nevada Solar One, now being pursued in desert areas around the world. The customers are utilities, which need to boost the amount of renewable energy they generate to meet government regulations.

But Sopogy's thinking small. Each individual collector produces 500 watts. That's roughly what a house consumes, but strung together in an array on the ground or on a roof, these panels could supply a chunk of a commercial building's needs, for example.

In a project in Hawaii, the company will be connecting several of its MicroCSP units together to generate one megawatt, according to Kimura. That plant, now in the permitting phase, is expected to go online in January of next year and be completed by late summer.

Last month Sopogy signed on Avista Utilities, based in Spokane, Wash., to test the system in northern Idaho scheduled to be operating by next summer.

Coal or natural gas-fired power plants can generate tens or hundreds of megawatts. But utilities are looking at different options for power generation during peak times, such as the middle of a hot day, when the demand--and price--of electricity is highest.

"On balance, CSP has a huge advantage in most cases over say, wind, because it produces power when people need it the most," said Alex Klein, an analyst at Emerging Energy Research. "CSP projects are effectively competitive at higher prices because they are generating electricity at peak times."

Solar systems--both thermal and photovoltaic--also have the advantage of being modular, so as they are scaled up, the price per kilowatt tends to go down, Klein added.

Corporations such as Wal-Mart, which is installing solar systems in Hawaii and California, invest in renewable energy to lock in to a fixed electricity rate over several years, while spiffing up their "green" credentials.

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