Jul 31, 2009
Drilling Space For Energy sciencetech” />
The Climate Conference in Bali allowed the littlest of UN nations: Palau, to express its desire to harness energy not from Earth resources, but from Space.
Backed by the Pentagon, the western Pacific island was investigating whether space-based solar power – beaming energy down from satellites – would provide affordable, clean, safe, reliable, sustainable and expandable energy for mankind.
Other climate change solutions discussed at the conference included, filling the skies with soot to block the sun, to cultivating oceans of seaweed to absorb the atmosphere’s heat-trapping carbon dioxide. Quietly the U.S. Defence Department 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.
But how do the 20,000 habitants of Palau come into this? Off Palau lies the uninhabited Helen Island. The proposal is to create a small demonstration project, in which a 260-foot-diameter “rectifying antenna,” or rectenna, is to take in 1 megawatt of power transmitted earthward by a satellite orbiting 300 miles above Earth. That would be enough electricity to power 1,000 homes, but on that empty island the project would be intended to show its safety. This mini demonstration is likely to cost $800 million and take till 2012 to complete.
Space power has been explored since the 1960s by NASA, 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.
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.
In response to this the European Space Agency has scheduled a conference on space-based solar power for 29th February 2008. Space Island Group, another entrepreneurial US endeavour, 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 UN’s Intergovernmental Panel on Climate Change, space power does not look like science fiction. The panel’s 2007 reports did not address space power’s potential Schock explained, because his team’s time horizon didn’t extend beyond 2030. However, 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.”
If you want to find out all the latest space news, why not subcribe to our RSS feed