JAPAN plans to build an orbiting power station to harvest solar energy and
beam it back to Earth. The newly formed Ministry of Economy, Trade and Industry
(METI) wants to start research into the Space Solar Power System this year and
begin operations in 2040.
The proposed satellite would weigh around 20,000 tonnes, be lifted to
geostationary orbit in several stages and have two solar panels each measuring
three kilometres by one kilometre. The station would convert solar energy into
microwaves and beam them back to Earth from a one-kilometre antenna. Osamu
Takenouchi of METI says the microwaves would not interfere with cellphones or
other communications on Earth.
METI estimates that it will have to spend around 拢11.5 billion on
construction at today鈥檚 prices. NASA shelved a similar project because of the
huge costs involved. Once in place, the station would produce 1 gigawatt of
power at a cost of 13.5 pence per kilowatt hour, compared to around 5 pence for
conventional power sources in Japan today.
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Tests on the energy-delivery system have already been completed by an airship
that beams microwaves to Earth. Researchers are now trying to make cheaper and
more efficient solar cells. 鈥淭his kind of energy source will also become more
important as global warming increases,鈥� says Takenouchi.
Molly Macauley at Resources for the Future in Washington DC, author of the
NASA report, 鈥淐an power from space compete?鈥� says the possible long-term health
effects of such high power densities at ground stations could be a problem.
鈥淓ven if there turned out to be little or no scientific data to support possible
harm, public 鈥榩erception鈥� may hinder deployment,鈥� she warns.