Posted on 04/16/2002 9:45:39 AM PDT by RightWhale
http://www.spaceref.com/news/viewpr.html?pid=8025
PRESS RELEASE
Date Released: Monday, April 15, 2002
American Institute of Physics
Getting power from the moon
If a physicist in Houston has his way youíll be able to say good-bye to pollution-causing energy production from fossil fuels. In the April/May issue of The Industrial Physicist Dr. David Criswell suggests that the Earth could be getting all of the electricity it needs using solar cells - on the moon.
In the article Criswell proposes a Lunar Solar Power (LSP) System, using arrays of solar cells on the lunar surface to beam energy back to Earth. Criswell estimates that the 10 billion people living on Earth in 2050 will require 20 Terrawatts (TW) of power. The Moon receives 13,000 TW of power from the sun. Criswell suggests that harnessing just 1% of the solar power and directing it toward Earth could replace fossil fuel power plants on Earth.
"The lunar operations are primarily industrial engineering," says Criswell. He and Dr, Robert Waldron first described LSP in 1984 at a NASA symposium on Lunar Bases and Space Activities in the 21st Century. "Adequate knowledge of the moon and practical technologies have been available since the late 1970ís to collect this power and beam it to Earth. The system can be built on the moon from lunar materials and operated on the moon and on Earth using existing technologies," reducing the expenses associated with transporting materials to the moon. He adds that LSP would be even cheaper if parts of the production machinery are designed to be made of lunar materials.
The LSP system consists of 20-40 lunar power bases, situated on the eastern and western edges of the moon, as seen from Earth. Each power base has a series of solar cells to collect energy from the sun, which is sent over buried electric wires to microwave generators that convert the solar electricity to microwaves. The generators then send the energy to screens that reflect the microwave beams toward Earth, where they are received by arrays of special antennas strategically placed about the globe. "Each antenna converts the microwave power to electricity that is fed into the local power grid," says Criswell.
"LSP is probably the only option for powering a prosperous world within the 21st century," says Criswell. "However, it does require a return to the moon." The system depends on some human occupation of the moon to build and run the lunar bases, but Criswell also sees this as an opportunity. "Once we are back and operating at large scale then going down the various learning curves will make traveling to the moon and working there ëroutine."
One problem is going to be the monthly cycle of lunar power available. When there is a new moon none of the solar collection stations on the near side (there is not a dark side of the moon, there is a near and far side) will have any power to transmit. Therefore you would need a transmission network on the moon to ship power to the near side month round.
More basically the solar flux on the moon is only higher then on earth by the atmospheric loss. If solar cells become economic (which is closer then most think, one more halving of cost, cost per watt looks kind of like Moores law) why not just put them on the earth. The duty cycle is no higher on the moon (in the light half the time) and production costs are going to be higher up there short of scifi nanotech.
I don't know if this is true to a measureable degree. They may be partially absorbed by water vapor at some wavelengths. In any case, the intent is to use an infinitesimal portion of the sun's radiation that is now going to waste, which is not power from the moon's gravitational potential. Not to say there isn't considerable power stored in the moon's kinetic energy if it can be released.
Not far-fetched at all. Technology is getting close to being able to build the space elevator. That is based on a long, flexible fiber attached at the equator to the earth and reaching to geosync orbit and somewhat beyond. Getting power down a 20 thousand mile cord might be a chore since high tension power lines have a practical transmission limit of about 300 miles due to line losses, but that might be just another engineering problem.
Not really true. Losses are a function of length, current and the resistance of the lines. But if you have a large enough price difference transmission lines can be any length.
Well, how about doing some extrapolation for us. We just launched a single I-beam, 40 feet long, and 240 miles into space. It cost $600 million, for this one beam. I don't know if launch costs were included in that or not.
Now, how much do you think building a moon based power plant would cost?
I also wonder how solar power would compete with nuclear power on the moon. If a lunar nuclear facility sets up operation on the moon would it not be easier to build than a massive solar array? That power could be transmitted anywhere in cis-lunar space just as easily. If they built a integrated breeder reactor to make a virtually closed-cycle nuclear process, virtually no new material would have to be mined and perhaps the breeder reactor could recieve nuclear waste from Earth for a fee. It could make money recieving nuclear waste and transmitting the power to whoever needs it. From a business perspective, a nuclear power plant may make more sense, especially if it's not subject to a million enviro-luddite regulations.
I don't know. My space development field is asteroid mining; I can give you some numbers for asteroid mining.
I agree totally. A compact nuclear plant versus a huge solar cell array would be no contest.
Doesn't this imply that 1% of the Moon's surface would have to be covered with solar cells? If so, that's an ENORMOUS project, in as much as the Moon's surface area is about equal to that of Africa's (imagine panelling over the entire continent of Africa!). Just guessing, but I doubt that any engineering feat approaching even a fraction of that magnitude has ever been accomplished on Earth (ito man-hours, cost, you name it).
Even more if they want a steady power output throughout the lunar diurnal cycle. It would be a huge project, but it might be manageable if they find efficiencies of scale.
Oops! I meant 1% of Africa. What's that equivalent to, panelling over the entire state of Rhode Island? Still a mighty big project.
Putting a solar array in geosynchronous orbit would not only be much cheaper than putting one on the moon; it would also be much better. A solar array in geosynchronous orbit would produce energy all day long except for a brief time during the night when it was eclipsed by the earth. Much better than the 50% duty cycles available on earth or the Moon. Still probably not worth the extra cost compared with putting one on earth, but at least halfway reasonable.
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