Solar power towers have maker beaming

www3.signonsandiego.com
August 6, 2009

As California and the nation seek to make electricity without burning fossil fuels, a new entrant jumped on the grid yesterday by focusing sunlight from 24,000 mirrors on a pair of towers north of Los Angeles. The 850-degree heat atop the 160-foot towers boiled water, and when the resulting steam spun a turbine on the ground, the plant built by Pasadena-based eSolar became the first commercial solar tower project in the United States. By utility standards, the Sierra SunTower is small – enough to power about 4,000 homes at its peak 5-MW production.

But eSolar has deals in place to build larger plants, about 600 MWs of peak power production in California and the Southwest, plus a GW in India. To produce more power, each plant would have more towers, up to 16 for each steam turbine. The company sells the equipment, other firms own the plants and sell the power. Two of California's biggest utilities, Southern California Edison and Pacific Gas and Electric, have signed deals to buy their power. San Diego Gas & Electric Co, has not.

eSolar is one of several companies racing for the answer of how to power American life without burning fossil fuels, and it's focusing on one of the two proven ways to make electricity from the sun: Photovoltaic panels, which make power from the light itself. Thermal systems, which harness the sun's heat, using fluids – ranging from hydrogen to steam to molten salt – to turn it into mechanical energy to drive generators. Neither method, so far, has proved as cost-effective as traditional power plants, and experts doubt there will be a one-size-fits-all solution.

In urban areas – and hazy or cloudy climates – photovoltaics can make sense because they're less complicated, smaller and can make power even with diffuse light. But for power sellers with access to large spaces with direct sunlight, the thermal systems can offer benefits because they can turn more of the sunlight into electricity and stop producing power more gradually when the sun goes away. Companies, with a big push from government, are working on ways to lower costs.

Some, such as FirstSolar, an Arizona company that has teamed up with San Diego-based Sempra Energy, are focusing on making a lot of inexpensive photovoltaic panels and spreading them on cheap desert land. Sempra says the power it produces at a plant outside Las Vegas is the cheapest solar energy on the market, but it won't reveal the cost, and says it is still more expensive than natural gas.

Others, such as Stirling Energy Systems, which has signed a deal with SDG&E, are focusing on efficiency. At a plant in the Imperial Valley, Stirling plans to have thousands of dishes pointed at the sun. In the middle of each dish, a solar engine driven by sun-heated hydrogen would drive a small generator. Other companies try to get more power from photovoltaic technology, or use tubes full of oil in solar troughs, mirrors in the shape of half-pipes, to drive steam turbines.

Bill Gross, the man behind eSolar, said he started thinking about solar energy as a teenager in suburban Los Angeles during the 1973 energy crisis. Trained as an engineer, he made solar devices before making a fortune in the software industry and founding Idealab in 1996 as a place to test ideas and build companies. The venture pioneered selling toys on the Internet and the search-engine advertising, and of late has been focused on green technology, including Vista electric car maker Aptera.

eSolar has attracted funding from Silicon Valley and Hollywood, including Google and Stephen Spielberg. "I've been dreaming of this day for more than 35 years," he said while unveiling the eSolar plant for investors, supporters, journalists and local politicians. "Up to now, solar electricity has remained a novelty because it failed a math test," he said. It is too expensive. His plant, he said, can produce electricity cheaper because it is made from mass-produced elements, quickly assembled on site and controlled by powerful computers.

Southern California Edison has agreed to buy all the electricity produced at the Lancaster plant. eSolar wouldn't say at what price it sells electricity, nor would it say how much the plant cost to build. But when PG&E asked state regulators to approve a deal for the output of a proposed 92-MW eSolar plant, it did not request a rate increase. It said the power is cheaper than other power available when the plant produces electricity. Utilities pay more for power when demand is high, such as on hot summer days.

Tom Mancini has been looking at a variety of technologies for Sandia National Labs, which does energy research for the government. "Who are going to be the winners and losers? We really don't know at this point," he said.