20-10-02 In the not-too-distant future, the moon could light up the Earth day and night. University of Houston researchers at the World Space Congress proposed ways to harness sunlight energy from the moon: Power plants constructed of native lunar materials that operate using simple microwave technology. They said it could solve the global energy crisis and cheaply power the planet indefinitely.
"The very things that make the moon bad for life -- a lack of air, water and atmosphere -- make it great for materials that could collect and beam to Earth the sun's rays," says UH physicist David Criswell, designer of the lunar solar power system. "Why bother building satellites? The moon is the perfect satellite."

Criswell, a self-described space cadet, has been dreaming lunar dreams since the 1970s. But his design may have a better chance of becoming a 21st century breakthrough than a 22nd century one thanks to recent advances by UH colleagues Alex Freundlich and Charles Horton. They're developing methods to manufacture huge solar cell arrays on the moon using materials in the lunar soil.
If the technology works, the UH team envisions it providing power not only to an energy-starved Earth but energizing a mining camp or industrial base on the moon. Criswell envisions the moon, much like mountains once thought too faraway and unliveable, drawing adventurous folks looking to get rich. But it is on Earth that the idea would be most revolutionary.

By 2050, a projected population of 10 bn might need four times the amount of electricity used now, Criswell says. But he says if a lunar power station harnessed just 1 % of the 13,000 TW of solar energy that strikes the moon, it could satisfy the planet's future appetite. One TerraWatt is equal to one trillion watts. And because it would make energy so cheaply, it could redistribute wealth.
Criswell says once the station is in place, it likely would drop people's energy bills to $ 200 a year, suddenly making energy affordable in the undeveloped world. Prosperity could follow. To make it happen, Freundlich, Horton and NASA scientists studied actual moon soil and simulated lunar dirt. Their conclusion: A robotic rover could melt surface lunar material into a thin glass sheet, upon which a thin film of solar cells could be applied. An extensive panel of such arrays could generate electricity from incoming solar rays.
"The raw materials, such as silicon, needed to make solar cells are present in the regolith, the moon's upper crust," says Freundlich. "And we should be able to make them more efficient than those used to power satellites and more resistant to the sun's radiation."

Of course, solar power is hardly a new idea. In the 1970s, environmentally sensitive engineers designed solar-powered cars and solar-heated homes. But the idea seemed impractical and never caught fire. The problem with terrestrial solar power is that the sun doesn't shine at night.
And even during the daytime, some sunlight gets blocked by clouds, bad weather, smog and otherthings. But except for once a year -- for about three hours during a full lunar eclipse -- the moon is exposed 24 hours a day to steady sunlight, which is 10 times stronger than it is by the time it reaches Earth. Plus, the moon has no weather.

Freundlich and Horton also are working on a variation of their solar cell technology, called thermo-photovoltaics, which directly converts heat into electricity. Their modifications will make the technology operate at much lower temperatures, which would be useful in deep space or on Earth.
"Using this technology to capture the heat generated at the heart of the coals in your barbecue grill, you could generate enough electricity to run kitchen appliances," says Horton.

But Criswell, who's published some 200 articles on an Earth-moon connection, remains most excited about what the solar cells can do for his lunar design. He envisions crews of thousands of people working six-month shifts on the moon and, at 61, he wants to be the first among them.
The solarcells would be less efficient than devices currently used on Earth, so those moon crews would have to lay down a singularly large number. Even so, they'd only have to cover 0.2 % of the moon's surface to meet all of Earth's power needs. That's as it should be, says Freundlich. Not only would a lunar surface entirely covered with cells produce far more power than needed, but the cells' violet anti-reflection coating would mean that from the Earth, the moon wouldn't look so bright.