Energy from Space to Be Explored

by Medindia Content Team on  December 24, 2007 at 2:48 PM Environmental Health   - G J E 4
Energy from Space to Be Explored
As global warming mounts and fossil fuels are getting exhausted anyway, man seems to be looking up to the skies - no, not for divine intervention, but to tap the solar power from the space itself.

The US defence establishment is already exploring the possibility of beaming energy down from satellites, something that could be clean, safe, reliable and sustainable.

The Pentagon recently issued a 75-page study conducted for its National Security Space Office concluding that space power — collection of energy by vast arrays of solar panels aboard mammoth satellites — offers a potential energy source for global U.S. military operations.

It could be done with today's technology, experts say. But the prohibitive cost of lifting thousands of tons of equipment into space makes it uneconomical.

In September, American entrepreneur Kevin Reed had proposed at the 58th International Astronautical Congress in Hyderabad, India, that Palau, a tiny western Pacific island nation could be an ideal spot for a small demonstration project, a 260-foot-diameter "rectifying antenna," or rectenna, to take in 1 megawatt of power transmitted earthward by a satellite orbiting 300 miles above Earth.

That's enough electricity to power 1,000 homes, but on that empty island the project would "be intended to show its safety for everywhere else," Reed told news agency AP in a telephone interview from California.

Reed said he expected his U.S.-Swiss-German consortium to begin manufacturing the necessary ultralight solar panels within two years, and to attract financial support from manufacturers wanting to show how their technology — launch vehicles, satellites, transmission technology — could make such a system work. He estimates project costs at $800 million and completion as early as 2012.

At the U.N. climate conference at Bali this month, a Reed partner discussed the idea with the Palauans who, Reed said,  could benefit from beamed-down energy if the project was expanded to populated areas.

"We are keen on alternative energy," Palau's president Tommy Remengesau Jr said. "And if this is something that can benefit Palau, I'm sure we'd like to look at it."

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 would be converted into microwaves for transmission to Earth, where it would be transformed into direct-current electricity.

Low-orbiting satellites, as proposed for Palau, would pass over once every 90 minutes or so, transmitting power to a rectenna for perhaps five minutes, requiring long-term battery storage or immediate use — for example, in recharging electric automobiles via built-in rectennas.

Most studies have focused instead on geostationary satellites, those whose orbit 22,300 miles above the Earth keeps them over a single location, to which they would transmit a continuous flow of power.

The scale of that vision is enormous: One NASA study visualized solar-panel arrays 3 by 6 miles in size, transmitting power to similarly sized rectennas on Earth.

Each such mega-orbiter might produce 5 gigawatts of power, more than twice the output of a Hoover Dam.

But how safe would those beams be?

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. The beams from giant satellites would likely require precautionary no-go zones for aircraft and people on the ground, he said.

But 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 Feb. 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 future energy with the U.N.'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 space — and maybe sooner."

Source: Medindia

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