New rays of hope for solar power’s future
High cost of fossil fuel and advanced technology improve this energy source’s prospects.
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To stimulate development, Spain has deployed hefty, long-term feed-in tariffs. But in the US market, solar thermal is hanging by a thread. The investment tax credit, which covers 30 percent of a CSP facility’s cost, will expire at year’s end unless renewed by Congress. But bills to renew the ITC have been blocked eight times this year by Senate Republicans.Skip to next paragraph
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“What we’re seeing with all these companies lining up for solar thermal is hugely promising,” says Monique Hanis, spokeswoman for the SEIA. “But without the ITC, all of these solar thermal plants will be put on hold.”
That would pour cold water on a raft of potential breakthrough solar-thermal technologies promoted by US companies. So far this year, five US-based start-up CSP companies have gotten $419 million in private funding for their technologies, Emerging Energy Research reports.
BrightSource Energy, Stirling Energy Systems, eSolar, Skyfuel, and Infinia Corp. are start-up US companies pursuing refinements of existing technologies – and major new ones – and the funding to prove them. One of the key goals is to make mirrors and receivers more efficient in order to achieve higher temperatures – which tend to make for greater efficiency and lower cost.
BrightSource Energy, funded by Google and others, received $100 million in May to proceed with its advanced “central receiver” approach. It has refined 1990s technology to develop simpler, cheaper to manufacture mirrors that focus the sun’s rays on a tower receiver, heating water to nearly 1,000 degrees F.
By contrast, Stirling Energy Systems in April received $100 million to further develop its “SunCatcher” approach – a relatively small system in which a 38-foot dish supporting 82 curved glass mirrors automatically tracks the sun. The solar heat is focused onto a high-efficiency four-cylinder reciprocating Stirling engine. The Stirling engine uses solar heat to expand (not burn) hydrogen gas to move its pistons, which spin an electric motor with no fuel cost or pollution.
Each SunCatcher dish generates about 25,000 watts, turning about 30 percent of the sun power that strikes it into electricity, compared with about 20 percent for parabolic-mirror systems.
Although the technology has yet to be proven on a commercial scale, Stirling Energy Systems announced in June that it had applied for permits to build a 750-megawatt “Solar Two” facility on 6,500 acres of desert in California’s Imperial Valley about 100 miles east of San Diego. When complete, the plant could supply power for about 500,000 homes.
Another technology called “linear fresnel” is being pursued by Ausra, which has opened a factory in Las Vegas to build inexpensive mirrors mounted on rolling platforms. Though operating at lower temperatures, the technology could operate at costs well below current levels, some observers say.
Back at Nevada Solar One, Mr. Kabel looks out across the desert to a hulking building on the horizon – a natural gas fired turbine power plant – an arch rival power producer. But maybe not for too much longer.
“The way things are going, with our costs coming down, this valley is going to see a lot more of these,” he says, gesturing to the rows of mirrors. “Fossil fuel generation is headed one way – like the dinosaurs.”