Wednesday, October 17, 2007

Space Based Solar Power

A new Pentagon study lays out the roadmap for a multibillion-dollar push to the final frontier of energy: a satellite system that collects gigawatts’ worth of solar power and beams it down to Earth.

Step-by-step explanation of how it works:
* A network of satellites would be constructed in space with arrays of lightweight mirrors extending for several miles (kilometers) on each side.
* Those mirrors would focus sunlight on solar cells, generating electrical power. The electricity would be converted into microwaves suitable for transmitting through Earth's atmosphere, at frequencies of 2.45 or 5.8 GHz.
* The microwaves would be directed down to antenna arrays on Earth, as a beam of radiation about one-sixth as intense as noon sunlight. The antennas would convert the radiation back into electricity for distribution via conventional grids.
Darn, only 1/6 as intense as noon sunlight. There goes my Bond villain idea of using it as a death ray.

The real question is how the economics of such an endeavor would work and if this would be a better option than land based photovoltaics. I am skeptical, but it might work when you see the value to the military:
Those factors still don't make space solar power attractive for commercial users, but a better case could be made for the Defense Department. The U.S. military pays a premium for its power in the battlefield, when you consider the cost of shipping oil out of the Middle East, refining it, then shipping the fuel back to the combat zone and burning it in electrical generators, Miller said. All that brings the current power price tag to $1 or more per killowatt-hour, compared with 5 to 10 cents on the domestic market, the report says.
Could you imagine them using this in Afghanistan? They would be surrounded by people who still use livestock as a form of transportation, and here they would be fueling up their base and gadgets with solar power from a satellite in space.

via MSNBC via Engadget


Rebelfish said...

If the military has such high costs for electricity already, you'd think normal solar would be a good choice for them. True, then they'd hafta carry around all the solar panels insteada just a big energy antenna, but you'd think they'd be able to make all their tents and cargo pods covered in flexible solar panels. Light, and available. I'm still not convinced that between getting these enormous space mirrors in orbit, converting to electricity (and it seems like it'd be harder to reject the heat from concentrated PV in a vacuum), converting to waves, transmitting, receiving, and converting to electricity can really be any more efficient (or cheaper) than earth-based concentrated PV (for homes/installations) or foil PV. Never mind the development cost!

Rebelfish said...

I was also slightly confused how the array could provide 24-hr/day electricity until I realized that their pictures in the article were crap and the satellite would actually orbit some 30 times as far away from the earth as shown in geostationary orbit.

Fat Knowledge said...


Yeah, I don't really understand the economics, but I agree with you that it will be hard to beat land based solar panels.

Post a Comment
