The Pentagon issued a report indicating that space-based solar power "has the potential to help the United States stave off climate change and avoid future conflicts over oil by harnessing the Sun's power to provide an essentially inexhaustible supply of clean energy." The report, from the Pentagon's National Security Space Office, calls for funding the development of space-based solar power culminating in 'a platform in geosynchronous orbit bigger than the international space station and capable of beaming 5-10 megawatts of power to a receiving station on the ground.' The Pentagon's interest in such an effort stems from the need to acquire energy on the battlefield, which today often comes at a painful premium."
Space-based solar power would use kilometre-sized solar panel arrays to gather sunlight in orbit: "A kilometer-wide geosynchronous solar panel could collect as much energy in one year as the amount contained within all known recoverable conventional oil reserves on Earth today". 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, solar power satellites placed in geostationary orbit above the Earth could operate at night and during cloudy conditions.
Why Space-Based Solar Power is Not a Great Idea ?
Billions of dollars to send to space what could be done on earth at a fraction of the price: Even if the sunlight is more intense in outer space, for the price of a kilometer wide collector you could build a terrestrial collector several times larger, more than enough to compensate for any light loss through the atmosphere.
Not to forget that terrestrial solar energy collectors are cheaper and faster to repair and maintain.
Space-based solar power collector or powerful weapon ? : Imagine a powerful solar powered satellite, capable of shooting a multi megawatt laser or microwave beam down to Earth.. (Let's pray they can hold focus)
10 billion dollars for only 10 Mega Watts is very expensive. We could (just for example) build more nuclear power plants and get 100,000 Mega Watts or invest funds in the Bussard's Polywell reactor. The Polywell is a nuclear fusion reactor that could generate several megawatts of energy and its radioactive wastes would be dangerous for about one hundred years, unlike fission reactors whose wastes remain dangerous for thousands of years.
"SBSP cannot be constructed without safe, frequent (daily/weekly), cheap, and reliable access to space and ubiquitous in-space operations": a satellite capable of supplying the same amount of electric power as a modern fossil-fuel plant would have a mass of about 4000 tonnes, almost 10 times that of the International Space Station. Sending that material into orbit would require more than a hundred rocket launches. Perhaps we should build a space elevator first.
