Solar Power from Space

By Virginia Prescott on Tuesday, September 8, 2009.

Isaac Asimov was one of the first to dream up the idea of getting solar power from space in his short story "Reason." Two engineers are assigned to a space station that uses microwave beams to supply solar energy to distant planets. The concept seems logical: after all, the sun never sets in space.

Now private companies, the Pentagon and even the Japanese government are interested in making solar power from space a reality.

California-based Solaren aims to collect solar power and then sent it back to earth via a satellite launched into orbit 22,000 miles above the earth’s equator. When deployed, the solar station would collect the sun’s rays and convert them into electricity, and then convert them into microwaves. Those waves will be beamed back to a receiving station, currently planned for construction outside of Fresno, Calif.

The cost of launching a solar satellite into space is significant. The National Security Space Office estimates that space-based solar power would cost as much as one billion dollars per megawatt.

This technology has not been widely tested, so there’s no way of knowing if it’s actually possible to convert solar power into microwaves and beam it through space. But there was a small but successful terrestrial experiment in Hawaii last year.

As part of our "next green thing" series, we’re joined by Michael Lemonick to discuss how feasible this technology is and whether it's worth the multi-billion dollar price tag. He’s a lecturer at Princeton University and a senior writer for Climate Central. He recently wrote about the possibility of space-based solar power for Yale Environment 360.

Yale Environment 360: Solar Power from Space: Moving Beyond Science Fiction

(Photo via Ethan Hein via Flickr/Creative Commons)

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A ridiculous figure. Most of the cost is the lift to GEO. Even using current rockets it would take only $100 B to lift a 5,000 ton, 1 GW power satellite to GEO. A B/MW is ten times too high.

For power satellites to make sense, they would have to under price coal at 1-2 cent per kWh. That requires a lift cost of $100/kg or less to GEO.

The investment is high, but it's not hard to get the cost down. A 300 ton mass ratio 3 rocket will give a laser stage 4 km/sec. Of the takeoff mass, 25 tons gets to GEO. At a million dollars, the cost is $40/kg.

The laser stage needs 8GW. At ten dollars a watt $80 billion. Written off over ten years, 8 billion. Running it at 100 tons per hour, 800,000 tons per year or 0.8 B kg, or $10/kg. So before labor and overhead, the cost of getting 100 t/hr to GEO is only $50.

There is a good deal of engineering development required, but if you want a solution to carbon and energy problems, this will do it. Google Henson oil drum for more.

Keith Henson

Submitted by Keith Henson on Wed, 09/09/2009 - 02:01.

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Word of Mouth is all about what's new. Online and on-air, the show looks at our fascinating and ever-changing world, and puts the latest ideas under a microscope. Word of Mouth investigates everything from science and technology, to health and the environment, to new trends in popular culture. The show airs Monday through Thursday at noon and is hosted by Virginia Prescott.