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The solar power stations in space

At some point in the near future a satellite orbiting the Earth will gently open a solar array like an unfolding flower and power from the Sun will pour down from it to both the Earth and the Moon, science fiction?

No, not one bit.

At this very moment a US robotic space craft, known simply as X37B, and powered by  a solar array that unfurled from its cargo bay is completing its 270th day in space and according to Professor Stephen Sweeney it is not only the shape of things to come, it is the way that our future will be powered.

For Professor Sweeney, the Head of Photonics at the UK’s University of Surrey, is an evangelist for a technology that first caught the popular imagination over 30 years ago in the Bond film ‘The man with the Golden Gun,’  the development of an orbiting solar array that can beam the Sun’s power straight down to anywhere it is wanted.

Though as Sweeney is quick to point out the technology he is working on will have one major difference, it will drive the collected solar energy down to its target in a harmless infra-red beam rather than the laser of the Bond film.

“Our power is going to come down in a very narrow beam and we have deliberately picked an infra-red frequency, because we want it to be safe, and to be able to come through the Earth’s atmosphere seamlessly. We want to make sure that it takes advantage of an atmospheric window so we don’t lose power.”

The idea is not new, a point Sweeney quickly concedes, some ten years ago scientists were talking about the possibility of creating space-based solar panels that would be the power stations of the future, but what is new is that much of what was talked about before can now be done.

The reason for some very serious money being pointed in the direction of projects like Sweeney’s and the attraction for that serious investment might seem even more ludicrous to the canny cash strapped, recession hit investor – a space station on the Moon, but for those with their eyes quite literally on the future that is where fortunes will be made.

The logic is simple, though the project is speculative to say the least.  The biggest cost of getting anything into space is the cost of getting it out of the Earth’s gravitational field.

A Moon base, with low gravity would be a perfect place for future space missions it would also present a site for space mining – an operation in which asteroids and other objects could be tethered close to the Moon and exploited for their mineral content the only problem to the plan is a lack of energy.

A prospect that may still be a long way off, but with much of the Moon in shadow and 14,000 km² in permanent darkness a constant source of power will be essential.

Step forward Professor Sweeney, one of the men who might help take the loon out of lunacy, for if the experiments Sweeney is conducting on the theory behind his solar power system work then it will be possible to beam power to the Moon and the Earth.

The idea as always is simple.

Solar energy is much more powerful in space because it is not filtered by the Earth’s atmosphere. A typical Earth-based solar cell is only 10-20% effective in space the yield can be taken up to 50% and converting it into a different more concentrated wave-length will mean that the atmospheric power loss can also be removed.

Even more compelling, is that freed from the Earth’s rotation the satellite can be powering energy down 24 hours a day from a space vacuum that should lower any costs from atmospheric wear and tear.

And as always in space you are never alone, two years ago two Japanese companies announced that they were getting ready to spend £13.4 billion on similar technology that will power 294,000 homes.

Mitsubishi Electric Corporation and IGI Corporation are partnering with the Japanese government on the space initiative, which  aims to generate about a gigawatt of energy from solar panel technology.

“It sounds like a science-fiction cartoon, but solar power generation in space may be a significant alternative energy source in the century ahead as fossil fuel disappears,” said Kensuke Kanekiyo, managing director of the Institute of Energy Economics.

The theory is convincing, but then so was the idea of crashing a rocket into one of the Moon’s poles to release water vapour from ice that scientists said that they had discovered there and kick start an atmosphere on our near neighbour.

But if Sweeney has his head in the stars, his backers are also looking very keenly at the potential spin-offs from such lofty research as the innovations necessary for just the optical tracking and power conversion involved would all be potentially valuable in other more Earth-based technologies.

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