A major complaint about renewable energy sources, including solar power, is that they don’t generate energy all the time. At night or during cloudy weather, solar arrays don’t produce electricity.
But it’s never nighttime or cloudy in space, and the U.S. military is taking steps toward creating a solar array larger than the International Space Station to orbit the Earth absorbing solar radiation and beaming down electricity through radio waves.
The Naval Research Laboratory has built a compact solar module capable of capturing and transmitting solar power from space. One side of the tile-shaped satellite features a photovoltaic panel. Inside the tile are the electronics that convert the resulting direct current to a radio frequency for transmission, and the other side supports an antenna to beam the power to Earth.
The panels performed well when tested under space-like conditions.
But they are just the building blocks of a much larger plan. Enough panels to stretch 9 football fields would be launched into space and assembled and attached by robots. Supported by a module to collect and reflect sunlight, the array would convert direct current into a radio frequency and send it to massive receivers on the ground.
The massive scale of the project makes it a gamble.
“The scale of things is where it starts to get really difficult,” said Mark Bünger, research director at Lux Research, because “the biggest problem is the cost of getting to space.” That’s why NRL has honed in on modular tiles that could be assembled by robots once in orbit.
The Navy lab is also at work on space robots, and the technology to build the earth-bound receivers already exists. But the project would still face questions about safety.
“People might not associate radio waves with carrying energy because they think of them for communications, like radio, TV, or cell phones. They don’t think about them as carrying usable amounts of power,” said lead engineer Paul Jaffe in a news release.
But there would also be some big benefits. The U.S. could call its wars for oil a thing of the past. And instead of sending diesel generators on trucks all around the world, or even, sometimes, dropping fuel canisters with parachutes, the military could power its remaining operations with a solar receiver.
The lower the frequency of the beam carrying the power, the more reliable it would be in extreme weather.
“At 2.45 gigahertz, you’ll get power in a monsoon,” Jaffe said.
With cleaner energy sources, climate change would be attenuated. For that reason, the Navy isn’t alone in taking concrete steps toward beaming power from space. The California utility company, PG&E, has committed to buying such power from space from the company Solaren by 2016. According to the International Academy of Astronautics, space solar power could be viable within 30 years.
Still, there could be a simpler solution to our energy woes: Build out the renewable infrastructure here on Earth. According to a recent Stanford report, it would be feasible and even cost-effective to do so.
