SACRAMENTO — Pacific Gas & Electric Co. for decades has generated power for its customers by splitting atoms, burning natural gas and capturing the force of falling water. More recently, the San Francisco utility began turning to the sun, wind, boiling geysers and even fermented cow manure to produce electricity.
Now, PG&E wants to turn to outer space.
A Manhattan Beach start-up called Solaren Corp. seeks to launch an array of giant solar power collectors into orbit 23,000 miles above Fresno and beam the energy to Earth. PG&E has signed a contract to buy the power -- if Solaren can make the technology work.
The proposal is a potential energy game-changer, supporters say. But, critics dismiss it as pie in the sky.
The scheme highlights a growing dispute as utilities struggle to meet ambitious requirements for energy from renewable sources: Should electricity come from big, bold projects such as huge desert fields of sunlight-reflecting mirrors or should it come from smaller, close-to-the-user efforts such as rooftop solar panels? Should big power companies handle electron delivery or do-it-yourselfers?
Solaren won't discuss the details or costs of its plan, other than to give a ballpark price tag at more than $2 billion, to generate enough electricity for 150,000 homes across much of Northern and Central California. It has asked utility regulators to keep the information confidential, for now.
But executives say that by 2016 they can put together the technology to harness energy that constantly bathes Earth from 93 million miles away.
"If our numbers are anywhere near where we think they will be, we will be able to provide power at a cost that's comparable with anything on Earth, that is much cleaner and all from space," says Gary Spirnak, Solaren's chief executive.
Spirnak points to a 2007 study by the National Security Space Office as evidence that a such a space-based power system is feasible:
"There is enormous potential for energy security, economic development, improved environmental stewardship, advancement of general space faring and overall national security for those nations who construct and possess a space-based solar power capability."
He acknowledges that raising more than $2 billion during a recession won't be easy, but says having a guaranteed power purchase agreement with PG&E should carry some weight with potential investors.
The Public Utilities Commission is reviewing Solaren's contract with PG&E, a unit of PG&E Corp. Regulators are charged with ensuring that the deal helps the utility meet a requirement to get one-fifth of its power from renewable sources by 2012. PG&E has asked for a ruling before Oct. 29.
Consumer advocates and more Earth-bound proponents of renewable energy are extremely skeptical.
California will be unable to meet its looming 20% renewable energy requirement, let alone a more ambitious 30% goal by 2030, if utilities and regulators continually embrace expensive, flashy and unproven technologies, they say. Policymakers, instead, should stick with reliable alternative sources -- such as geothermal, wind and centralized solar, sunlight concentrated by mirrors -- that have been operating commercially for decades.
"There are a lot of speculative plays," says V. John White, director of the Center for Energy Efficiency and Renewable Technology in Sacramento. "We have a lot of PowerPoints floating around that I don't think will turn into power plants."
The concept behind space-based solar power is simple, Solaren says.
Four or five rocket launches would be needed to put enough solar collectors into a stationary orbit to produce 200 megawatts of power, about half the output of a modern natural-gas-fired plant. The solar energy would be converted radio waves and beamed to a receiving station in Fresno, leaving unscathed any birds or airplanes that get in the way of the highly diffused beam. There, it would be converted to either alternating or direct electric current and dispatched to customers via high-voltage transmission lines.
Spirnak acknowledges that nothing on this scale has been attempted, but the basic technology is proven. Commercial communications satellites have been powered by solar energy for more than four decades. The satellites use the sun's power, available 24 hours a day in space, to make electricity. The electricity is turned into radio waves to bounce television, telephone and other signals around the globe.
Experience with larger scale, experimental radio transmissions converted to electrical power is limited, PG&E wrote in the regulatory filing. In 1975, NASA's Jet Propulsion Laboratory transmitted 34 kilowatts of energy about a mile. Last year, a former JPL scientist, John Mankins, transmitted a small amount of power generated by ground-based solar cells 92 miles between two Hawaiian islands.
"The challenge," PG&E spokesman Jonathan Marshal says, is "putting enough hardware up in space and doing it economically."