California's new power source a solar farm ENERGY

Space-based solar power plants have been discussed for decades and could take many shapes. In this artist's rendering, mirrors focus sunlight on solar panels. Solaren has not yet revealed the design of its orbiting power plant, which will sell power to PG&E. less Space-based solar power plants have been discussed for decades and could take many shapes. In this artist's rendering, mirrors focus sunlight on solar panels. Solaren has not yet revealed the design of its ... more Photo: ©Mafic Studios, Inc. Photo: ©Mafic Studios, Inc. Image 1 of / 1 Caption Close California's new power source a solar farm 1 / 1 Back to Gallery

California's next source of renewable power could be an orbiting set of solar panels, high above the equator, that would beam electricity back to Earth via a receiving station in Fresno County.

Pacific Gas and Electric Co. has agreed to buy power from a startup company that wants to tap the strong, unfiltered sunlight found in space to solve the growing demand for clean energy.

Sometime before 2016, Solaren Corp. plans to launch the world's first orbiting solar farm. Unfurled in space, the panels would bask in near-constant sunshine and provide a steady flow of electricity day and night. Receivers on the ground would take the energy - transmitted through a beam of electromagnetic waves - and feed it into California's power grid.

The idea has been discussed for decades. It appeared in science fiction as far back as 1941 and later received serious study by NASA and the Pentagon. At times, it has been dismissed as fantasy.

But San Francisco's PG&E considers it realistic enough to support. The company asked the California Public Utilities Commission on Friday for permission to buy 200 megawatts of electricity from Solaren's orbiting power plant when and if it's built. That's enough electricity for 150,000 homes.

"We're convinced it's a very serious possibility that they can make this work," said PG&E spokesman Jonathan Marshall. "It's staggering how much power is potentially available in space. And I say 'potentially' because a lot remains unknown about the cost and other details."

Many of the project's details remain under wraps, and others haven't been decided yet, said Cal Boerman, Solaren's director of energy services. For example, Solaren still hasn't decided whether to use crystalline silicon solar cells or newer, thin-film cells that weigh less than silicon but aren't as efficient.

But the young company, a collection of aerospace engineers based in Manhattan Beach (Los Angeles County), has the technology and expertise to make it work, Boerman said.

"We'd all read about it, thought about it, and it seemed to be a good, next challenging project for the space industry," he said. "The timing is right."

Not a 'laser death ray'

He also dismissed fears, raised in the past, that the transmission beam could hurt birds or airline passengers who stray into its path. The beam would be too diffuse for that.

"This isn't a laser death ray," Boerman said. "With an airplane flying at altitude, the sun is putting about four or five times more energy on the airplane than we would be."

Placing solar panels in orbit would solve two of the biggest problems facing the solar industry.

Terrestrial large-scale solar farms only generate electricity during the day, and their output varies with the seasons. They also require large tracts of land, often hundreds of acres for a single installation.

Those problems vanish in space. The Solaren project would experience constant sunlight except for brief interruptions during the spring and fall equinox periods. Obviously, land wouldn't be an issue. And the sunlight hitting Solaren's facility would be eight to 10 times more powerful than the light reaching Earth through the planet's atmosphere.

Failure to launch

But orbiting solar installations face their own difficulties, problems that have kept the idea Earth-bound for decades.

Space is a harsh environment, and equipment sent there must be able to operate year after year without repairs. Lifting the gear into orbit is expensive and a bit risky, since some rocket launches fail. Boerman said the solar installation would require four rocket launches. It would not, however, require assembly by astronauts, instead unfolding on its own in space.

"Obviously, there are going to be a lot of very hard questions," said Ralph Cavanagh, head of the energy program at the Natural Resources Defense Council. "My prediction is this is going to be much more about economics than the environment."

PG&E has not disclosed how much money it has agreed to spend on Solaren's electricity, money that would come from the utility's customers.

"I can say it will be comparable to other renewable energy that's been approved recently by the California Public Utilities Commission," Marshall said.

Global crunch

Like California's other utilities, PG&E is under state orders to expand its use of renewable power as part of California's fight against global warming. By the end of 2010, 20 percent of the electricity PG&E sells must come from renewable sources. The utility has been signing contracts with companies planning wind farms and large solar arrays, but some of those projects have been stalled by the global credit crisis.

Mark Toney, head of The Utility Reform Network watchdog group, fears that the difficulty of meeting the state's requirements has pushed PG&E into supporting an expensive distraction.

"It really seems like an act of desperation," he said. "We really think PG&E should be spending more time on proven technologies closer to home that we can really count on. This just seems so remote, in more ways than one."

Cavanagh said, however, that given the world's problems of global warming and rising demand for energy, utilities need to explore some unconventional ideas.

"You want to encourage them to try lots of different things," he said. "But the caution is that some of these things won't work."