Alternative Energy

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Solar Company Says Its Tech Can Power 90 Percent of Grid AND Cars

By Alexis Madrigal March 06, 2008 - Wired Blog Network

The solar power plant company, Ausra, has released a paper claiming that solar thermal electric technology can provide 90% of US grid electricity, with enough left over to power a fleet of plug-in hybrids. The company estimates that change over would eliminate 40% of the country's greenhouse gas emissions with a land footprint of 9600 square miles (thanks, Kent).

The key to the scenario, however, is developing the ability to store energy for 16 hours to create a stable power source through cloudy periods and the night, a feat which has so-far eluded engineers.

"If we can do storage," Ausra CEO Bob Fishman said, "We can take on coal."

The paper says that Ausra expects to commercialize their energy storage technology within two years. A prototype of that system will go into the prototype plant the company will finish this summer in Bakersfield, California, the company's founder David Mills, who is also author of the paper, told Wired.com. The research was presented at the IEA SolarPACES conference in Las Vegas, and is described as peer-reviewed. It is available here for your inspection.

Solar thermal power is gaining adherents, including Google.org who cut a deal with another player eSolar, as a way to cleanly generate cost-competitive, city-scale amounts of power. Unlike traditional photovoltaics, which use panels to convert sunlight into electricity, solar thermal plants focus the sun's rays on liquids to make steam which powers turbines. Solar thermal is flat-out more efficient at 20-40 percent than photovoltaics, which in the field convert sunlight to electricity at about 15-22 percent. And solar thermal fits into the industrial model of power production, meaning that it works in big plants, not distributed across a bunch of houses and buildings.

Mills paper reveals some interesting statistics about the construction cost of solar thermal technologies: $3000 per kilowatt of capacity, but estimated to drop to $1500 per kW over the next "several" years. Last year, The New York Times quoted GE Energy executives giving construction costs for coal plants at $2,000 to $3,000 per kilowatt.

Ausra says they can generate electricity for 10 cents a kilowatt hour, which is close to the cost of natural gas, and they expect the price to drop even further. The company has received a lot of attention because of their compact linear fresnel reflector technology, and because they lined up two big-name VC early: Vinod Khosla and Kleiner Perkins, where Al Gore is a partner. They've received $43 million in venture capital, and an additional $30 million at least in venture debt. Later this year, they are planning a $100-150 million funding round.

Ausra, for now, sells power to utilities. In total, they have announced real commitments for 1,500 megawatts of solar power deployments from PG&E (1000 MW) and Florida Power and Light (500 MW). Fishman, however, says they have several thousand more megawatts of deals in the pipeline. A recent deal between a different solar player, Abengoa, and Arizona Public Services, for a 280 megawatt plant had the following terms: 30 years, $4 billion.

Still, there are reasons to be skeptical. For one, companies have been piling into the solar concentrating space. Stirling Energy Systems, SkyFuel, Solel, BrightSource, Rocketdyne, Abengoa, and the aforementioned eSolar are all working on using mirrors to concentrate the sun's energy in one way or another. That's a lot of competition for a still-small chunk of the energy business.

Perhaps a more fundamental question is: can all these prospective plants actually get built? Conceptually, solar thermal is a real bright spot in an otherwise depressing renewable energy landscape, but until there are dozens of functional plants, it will be hard to know what kind of engineering costs these facilities are going to run into. And that's assuming that the storage technologies being discussed turn out to work. There's a long road from a prototype plant in Bakersfield to providing 90% of the nation's electric needs. For one, the nation's electricity transmission infrastructure would have to change considerably as well, but that's a topic for another post.

In the near term, these companies will be feeding off states in the Southwest that have built solar requirements into their renewable energy dictums. Nevada, Arizona, New Mexico, and Colorado all require between 15 and 20 percent of their power to come from solar sources. Solar thermal is the only technology that could realistically deliver that type of power. Any sort of system that puts a price on emitting carbon dioxide -- either a carbon tax or a cap-and-trade framework -- would be helpful because it would penalize coal and aid cleaner technologies.

Ultimately, though, these companies want to dominate the grid, as Mills wrote in the paper, solar thermal "is probably the only currently available technology which can be considered for a globally dominant role in the electricity sector over the next 40 years." To achieve a dominant role globally, including China and India in the picture, they'll have to fulfill Google's dream of making renewable energy less expensive than coal.

http://blog.wired.com/wiredscience/2008/03/solar-company-s.html