Solar Power Concentrate
Space power has been explored since the 1960s by NASA and the Japanese and European space agencies, based on the fundamental fact that solar energy is eight times more powerful in outer space than it is after passing through Earth's atmosphere.
The energy captured by space-based photovoltaic arrays could be converted into microwaves for transmission to Earth, where the rectennas would transform it into direct-current electricity.
Low-orbiting satellites, as proposed for Palau, would pass over a target area once every 90 minutes or so, taking about five minutes to transmit energy to be stored in batteries or used immediately. Electric cars, for example, could take such a charge via built-in rectennas.
This proposal differs from many other space-power studies, which focus on geostationary satellites that would orbit 22,300 miles (36,000 kilometers) above the Earth and remain over a single location to transmit a continuous flow of power.
The scale of that vision is enormous: One NASA study visualized solar-panel arrays three by six miles (five by ten kilometers) in size, transmitting power to similarly sized rectennas on Earth.
Each such mega-orbiter might produce five gigawatts of power, more than twice the output of a Hoover Dam.
Patrick Collins of Japan's Azabu University, who participated in Japanese government studies of space power, said a lower-power beam, because of its breadth, might be no more powerful than the energy emanating from a microwave oven's door, whereas the beams from giant satellites would likely require precautionary no-go zones for aircraft and people on the ground.
Space Energy's Potential
Rising oil costs and fears of global warming will lead more people to look seriously at space power, boosters believe.
"The climate change implications are pretty clear. You can get basically unlimited carbon-free power from this," said Mark Hopkins, senior vice president of the National Space Society in Washington.
"You just have to find a way to make it cost-effective."
Advocates say the U.S. and other governments must invest in developing lower-cost space-launch vehicles. "It is imperative that this work for `drilling up' vs. drilling down for energy security begins immediately," concludes October's Pentagon report.
Some seem to hear the call. The European Space Agency has scheduled a conference on space-based solar power for next February 29. Space Island Group, another entrepreneurial U.S. endeavor, reports "very positive" discussions with a European utility and the Indian government about buying future power from satellite systems.
To Robert N. Schock, an expert on the UN's Intergovernmental Panel on Climate Change, space power doesn't look like science fiction.
The panel's 2007 reports didn't address space power's potential, Schock explained, because his team's time horizon didn't extend beyond 2030. But, he said, "I wouldn't be surprised at the beginning of the next century to see significant power utilized on Earth from spaceand maybe sooner."
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