Tuesday, January 13, 2009

Space Solar Power: Beam It Down, Scotty

It's feasible but for the cost

In the Dec. 4 edition of The Economist, a case was made for the ultimate in energy efficiency, space solar power (SSP). Light from the sun is the cleanest and most abundant for of energy; about 1.3 gigawatts (GW) of energy pours through to every square kilometer on the planet. In SSP, sunlight could be captured by vast arrays of photovoltaic cells mounted on a satellite in orbit around the Earth. (See full article: http://www.economist.com/science/tq/displaystory.cfm?story_id=12673299)

Ideally, arrays would be placed on a geostationary satellite about 36,000 kilometers up resulting in 24-hours of microwave transmission to receiving arrays on Earth as the planet spins (see Illustration). Unlike ground-based panels, SSP panels don't have to contend with weather and are illuminated constantly. Better yet, because there is no atmosphere to deal with (microwave beams pass straight through) the solar radiation is five times more than it is on the ground. Power density of the beam at the receiver would be slightly more than what leaks from a typical home microwave oven so nothing is incinerated on Earth, as one might think. Microwaves are currently used by the telecommunications industry worldwide with no damage to humans or wildlife.

Explaining the importance of SSP, the National Space Society online says most spacecraft already use solar power and when taken to a larger scale, combined with already demonstrated wireless power transmission, can supply nearly all the electrical needs of our planet. The article continues...

"Another need is to move away from fossil fuels for our transportation system. While electricity powers few vehicles today, hybrids will soon evolve into plug-in hybrids which can use electric energy from the grid. As batteries, super-capacitors, and fuel cells improve, the gasoline engine will gradually play a smaller and smaller role in transportation - but only if we can generate the enormous quantities of electrical energy we need. It doesn't help to remove fossil fuels from vehicles if you just turn around and use fossil fuels again to generate the electricity to power those vehicles. Space solar power can provide the needed clean power for any future electric transportation system." (See full story: http://www.nss.org/settlement/ssp/)

This form of space solar power can be implemented with today's technology but the cost is exorbitant. For comparison's sake, hydropower produces the cheapest cost per kilowatt hour at about four cents wholesale; coal-produced power is about ten cents; standard solar power 15-25 cents per kWH and SSP would be 50 cents! The reason is the sheer mass of such a project; the planning, engineering, international coordination, hardware construction, launch and assembly of the system could make it financially impossible. However, once in place, the space panels could produce as long as 50 years so the cost could amortize over time and actually could be a bargain when greenhouse gases/global warming reductions are factored in.

During the new Obama Administration clean energy innovations could prove to be the answer to reducing global warming, adding non-exportable jobs and making the U.S. the world's technological leader once again. "Clean Energy Now" must be our mantra.


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