How to harvest solar power? Beam it down from space!

The satellites would electromagnetically beam gigawatts of solar energy back to ground-based receivers, where it would then be converted to electricity and transferred to power grids. And because in high Earth orbit, satellites are unaffected by the earth's shadow virtually 365 days a year, the floating power plants could provide round-the-clock clean, renewable electricity. NASA and the United States Department of Energy studied the concept throughout the 1970s, concluding that although the technology was feasible, the price of putting it all together and sending it to outer space was not.

Skyrocketing oil prices, a heightened awareness of climate change and worries about natural resource depletion have recently prompted a renewed interest in beaming extraterrestrial energy back to Earth, Miller explained.

And so has a 2007 report released by the Pentagon's National Security Space Office, encouraging the U.S. government to spearhead the development of space power systems.

"A single kilometer-wide band of geosynchronous Earth orbit experiences enough solar flux in one year to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today," the report said.

The study also concluded that solar energy from satellites could provide power for global U.S. military operations and deliver energy to disaster areas and developing nations.

"The country that takes the lead on space solar power will be the energy-exporting country for the entire planet for the next few hundred years," Miller said.

Russia, China, the European Union and India, according to the Pentagon report, are interested in the concept. And Japan, which has been pouring millions of dollars into space power studies for decades, is working toward testing a small-scale demonstration in the near future.