Solar Thermal Plants Go Back to the Future

By Martin LaMonica
September 9, 2007

Solar thermal technology, which uses heat to generate electricity,
is on its comeback tour.

Like a rock band that took an extended hiatus, solar thermal technology was
essentially abandoned in the 1990s after a handful of power plants were
constructed in the 1980s.

But on Monday, solar thermal start-up Ausra is expected to announce that it has
attracted $40 million in funding from venture capital firms Kleiner Perkins
Caufield & Byers and Khosla Ventures.

The company is also expected to disclose that it has begun the permit process to
build a 175-megawatt power plant in California that should be operating in about
three years.

Ausra, which has sought to keep a low profile, said that its product design will
make its power plants competitive with fossil fuel-based electricity in the next
few years.

"We're talking about the U.S. producing its electricity and electricity for
vehicles entirely within its borders. The implications for this are enormous,"
said David Mills, Ausra's founder and chief scientific officer who spent several
years doing the basic research for the company's technology.

Ausra's plants are made up of hundreds of glass-covered metal "collectors" that
concentrate sunlight on a tube filled with water. The water becomes steam which
turns a conventional steam turbine.

High-pressure water storage tanks allow the company's solar thermal power plants
to keep several hours' worth of electricity on tap, addressing one of the
biggest hurdles of large-scale renewable energy, according to company executives.

"Energy storage is the key to enabling renewable sources of power to move from
10 to 20 percent of electricity generation to 90-plus percent," said Ausra
Executive Vice President John O'Donnell.

Ausra executives said that the system can now deliver electricity at 10 cents
per kilowatt hour, more than the 9 cents per kilowatt hour that natural gas
power plants cost.

Once Ausra's manufacturing operations are working on a large scale, its
production costs and cost of capital will go down below the price of coal-fired
plants which are 6 cents per kilowatt hour, he said.

Because of regulations that require renewable sources of electricity, a number
of companies are now pursuing utility-scale solar thermal power plants. Another
start-up, Green Volts, recently signed a supply deal with Pacific Gas & Electric
in California.

The U.S. National Renewable Energy Laboratories estimates that solar thermal
technology can supply hundreds of gigawatts of electricity, or more than 10
percent of demand.


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