July 24, 2008
Harvest the Sun – From Space Alternative Energy Source
By O. Glenn Smith
As America faces $4.50 a gallon gas, we also know that alternative energy sources - coal, oil shale, ethanol, wind and ground-based solar - are either of limited potential, very expensive, require huge energy storage systems or harm the environment. There is, however, one potential future energy source that is environmentally friendly, has essentially unlimited potential and can be cost competitive with any renewable source: space solar power.
Science fiction? Actually, no - the technology already exists. A space solar power system would involve building large solar energy collectors in orbit around the Earth. These panels would collect far more energy than land-based units, which are hampered by weather, low angles of the sun in northern climes and, of course, the darkness of night.
Once collected, the solar energy would be safely beamed to Earth via wireless radio transmission, where it would be received by antennas near cities and other places where large amounts of power are used. The received energy would then be converted to electric power for distribution over the existing grid. Government scientists have projected that the cost of electric power generation from such a system could be as low as 8 to 10 cents per kilowatt-hour, which is within the range of what consumers pay now.
In terms of cost effectiveness, the two stumbling blocks for space solar power have been the expense of launching the collectors and the efficiency of their solar cells. Fortunately, the recent development of thinner, lighter and much higher efficiency solar cells promises to make sending them into space less expensive and return of energy much greater.
Much of the progress has come in the private sector. Companies like Space Exploration Technologies and Orbital Sciences, working in conjunction with NASA's public-private Commercial Orbital Transportation Services initiative, have been developing the capacity for very low cost launchings to the International Space Station. This same technology could be adapted to sending up a solar power satellite system.
Still, because building the first operational space solar power system will be very costly, a practical first step would be to conduct a test using the International Space Station as a "construction shack" to house the astronauts and equipment. The station's existing solar panels could be used for the demonstration project, and its robotic manipulator arms could assemble the large transmitting antenna. While the station's location in orbit would permit only intermittent transmission of power back to Earth, a successful test would serve as what scientists call "proof of concept."
Over the past 15 years, Americans have invested more than $100 billion, directly and indirectly, on the space station and supporting shuttle flights. With an energy crisis deepening, it's time to begin to develop a huge return on that investment. (And for those who worry that science would lose out to economics, there's no reason that work on space solar power couldn't go hand in hand with work toward a manned mission to Mars, advanced propulsion systems and other priorities of the space station.)
In fact, in a time of some skepticism about the utility of our space program, NASA should realize that the American public would be inspired by our astronauts working in space to meet critical energy needs here on Earth.
O. Glenn Smith is a former manager of science and applications experiments for the International Space Station at NASA's Johnson Space Center.
Originally published by The New York Times Media Group.
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