Astrium Hopes To Test Grabbing Solar Energy From Orbit

goldaryn writes "Word from the BBC today is that Europe's biggest space company is seeking partners to help get a satellite-based solar power trial into orbit: 'EADS Astrium says the satellite system would collect the Sun's energy and transmit it to Earth via an infrared laser, to provide electricity. Space solar power has been talked about for more than 30 years as an attractive concept because it would be 'clean, inexhaustible, and available 24 hours a day.' However, there have always been question marks over its cost, efficiency and safety. But Astrium believes the technology is close to proving its maturity.'"

Comments

Re:Why use lasers?

[bughunter]

Why use lasers?

Conversion efficiency. Lifetime. Environmental suitability. Potential for technology insertion and incremental improvements.

The magnetron, while efficient at converting electrical power to microwave, is being surpassed by the VECSEL solid-state IR laser in efficiency. Both are about 70-75% efficient, but magnetrons are a rather old, very mature technology whereas solid state lasers are still maturing. Magnetrons are at their limit; solid-state lasers still have room for improvement.

And solid state devices can more easily be made to have a long service lifetime and to tolerate being shaken nearly to death on top of a rocket than magnetrons can. These are satellite applications, so reliability, service life and ruggedness are very important requirements.

For conversion back to electrons, I'm not so sure of that trade, but I trust they factored that in. IR is quite suitable mainly because a microwave transducers have some fundamental drawbacks. A microwave receiver is a bolometer, or bolometer array, which works best when incident power is focused on a nonlinear element, so some sort of refractive "lens" element will be needed, most likely an array of refractive concentrators. In the infrared, however, photovoltaic cells can be distributed over a wide area - and again, they are a maturing technology that is getting cheaper and more efficient with time... all in all I'm not surprised they chose IR.