Saturday, October 13, 2007

Solar Power from Space

Illustration: Mafic Studios

A report released by the National Security Space Office recommends that the US government sponsor projects to demonstrate solar-power-generating satellites and provide financial incentives for further private development of the technology.

Space-based solar power would use kilometre-sized solar panel arrays to gather sunlight in orbit. It would then beam power down to Earth in the form of microwaves or a laser, which would be collected in antennas on the ground and then converted to electricity. Unlike solar panels based on the ground, satellites placed in geostationary orbit above the Earth can operate at night and during cloudy conditions.

The NSSO report (pdf) recommends that the US government spend $10 billion over the next 10 years to build a test satellite capable of beaming 10 megawatts of electric power down to Earth.
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At the same press conference, over a dozen space advocacy groups announced a new alliance to promote space solar power – the Space Solar Alliance for Future Energy. These supporters of space-based solar power say the technology has the potential to provide more energy than fossil fuels, wind and nuclear power combined.

The NSSO report says that solar-power-generating satellites could also solve supply problems in distant places such as Iraq, where fuel is currently trucked along in dangerous convoys and the cost of electricity for some bases can exceed $1 per kilowatt-hour. The report also touts the technology's potential to provide a clean, abundant energy source and reduce global competition for oil.

The US abandoned the idea as economically unfeasible in the 1970s. Advances in photovoltaics, electronics and robotics will bring the size and cost down to a fraction of the original schemes, and eliminate the need for humans to assemble the equipment in space.

Several technical challenges remain to be overcome, including the development of lower-cost space launches. A satellite capable of supplying the same amount of electric power as a modern fossil-fuel plant would have a mass of about 3000 tonnes – more than 10 times that of the International Space Station. Sending that material into orbit would require more than a hundred rocket launches. The US currently launches fewer than 15 rockets each year.

In spite of these challenges, the NSSO say no fundamental scientific breakthroughs are necessary to proceed with the idea and that space-based solar power will be practical in the next few decades.

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