In space solar power concepts, solar panel arrays would gather sunlight in orbit, then beam it to Earth (Illustration: Mafic Studios)

Energy beamed down from space is one step closer to reality, now that California has given the green light to a deal involving its sale. But some major challenges will have to be overcome if the technology is to be used widely.

On Thursday, the California Public Utilities Commission gave its blessing to an agreement that would see the Pacific Gas and Electric Company buy 200 megawatts of power beamed down from solar-power satellites beginning in 2016.

A start-up company called Solaren is designing the satellites, which it says will use radio waves to beam energy down to a receiving station on Earth.

The attraction of collecting solar power in space is the virtually uninterrupted sunshine available in geosynchronous orbit. Earth-based solar cells, by contrast, can only collect sunlight during daytime and when skies are clear.


Launch costs

But space-based solar power must grapple with the high cost per kilogram of launching things into space, says Richard Schwartz of Purdue University in West Lafayette, Indiana. Schwartz chaired a US National Academies committee that in 2001 wrote up an assessment of NASA’s space-based solar power research. “If you’re talking about it being economically viable for terrestrial power, it’s a tough go,” he says.

Cal Boerman, Solaren’s director of energy services, says the company designed its satellites with a view to keeping launch costs down. “We knew we had to come up with a different, revolutionary design,” he says. A patent the company has won describes ways to reduce the system’s weight, including using inflatable mirrors to focus sunlight on solar cells, so a smaller number can collect the same amount of energy.

Stay cool

But using mirrors introduces other challenges, including keeping the solar cells from overheating, says Schwartz. “You have to take care of heat dissipation because you’re now concentrating a lot of energy in one place,” he says.

According to the company’s patent, Solaren’s solar cells will be connected to radiators to help keep them cool.

Though Boerman says the company believes it can make space-based solar power work, it is not expecting to crowd out other forms of renewable energy. Laws in California and other states require increasing use of renewable energy in coming years, he points out. “To meet those needs, we’re going to need all types of renewable energy sources,” he says.