According to an article recently printed in The Industrial Physicist in order for everyone in the world to be adequately powered by 2050, an electric output 3-5 times greater than what is available now must be produced (roughly 20 terawatts), and it must be provided at 1/10 the current cost (about $.004.) The author David Criswell states that current means of power are not only too expensive, but also too polluting and unsafe. Nuclear power faces too much political and social opposition, and nobody much likes the idea of nuclear material getting in the wrong hands. Also, it is unlikely fusion power will be around by then. Solar power is too subject to the weather, and tide and geothermal systems will not be in high enough abundance. Wind power would take up too much land area. So what is it we can do to solve this problem? Criswell says solar power from space may be the answer.

Although he mentions the older idea of orbital satellites that receive solar power and transmit it to earth, he argues against such a proposal as inefficient compared to his plan. It would be both too expensive and would require way too much material being shipped into space. Instead he says, we must look to the moon for our source of power.

Strategically placed receiving stations around the world would receive power equaling 200 Watts per sqaure meter of receiving area. The power would be beamed from collection stations on the moon via 12-cm microwaves that would be able to pass through clouds and provide power during the night, things natural light is incapable of. The microwave would be harmless to both people and animals; anyone entering the beam would merely feel slightly warm, although people would not be permitted into the power grid on a regular basis and workers could be easily shielded. The only shortcoming is the microwave frequency would interfere with some wireless communication sources (especially cellular phones) which would have to be relegated to another frequency.

The power itself would be collected on the moon by a system of 10-20 pairs of bases, each of which consinsts of solar cells to collect sunlight, and buried wires to transmit it to the microwave generators. The technology to pull off such an operation already exists and it would be much more cost effective than building such a system in orbit as most of the materials could be built on the moon after an initial investment of machinery and personnel. The moon is also a more friendly enviorment for solar panels-no corrosive air, errosive wind, or rain and hail. Criswell vouches that moonquakes and micrometeors would have a negligable effect on the panels themselves. A limited working system could be produced in as little as ten years, and satellites could deflect microwaves to areas that are in too high or low a latitude, or that are not facing the moon at a given time.

David R. Criswell. "Solar Power via the Moon." The Industrial Physicist April/May 2002.

Criswell's idea is not a new one by any stretch of the imagination, such ideas have been bandied around concept labs for decades now. I have read a great number of articles on alternative power generation, and there seems to be a recurring problem with 'beam of ____ energy from space down to earth' ideas.

Consider this. Sphere A (the earth) is orbited sphere B, the moon. Sphere B rotates in such a way that one plane constantly faces A, while A rotates quite quickly. If you direct a laser beam from B to A, the laser will transit across the surface of A due to A's rotation. Even if you attenuate your antenna to track the receiving station, the circular locus of the beam will slowly become a very long ellipse, quickly covering a larger area than any practical receiving station could. Assume then that you want to 'turn off' the beam and switch to a different station. Easy enough, but space-based installations are notorious for breaking after long periods of time. Cosmic rays and micrometeorites will degrade the transmitter arrays, and inevitably one of them will lock on a particular beam vector. This could cause havoc depending on the type of beam used.

If it's plain sunlight, you'll create a laser-like beam that will scorch vegetation (you've used a magnifying glass on ants right?), heat-crack concrete and burn people alive. If at a lower intensity, people will still be blinded by the beam, and in the long term end up with skin cancer. If you're using microwaves, the problems (surprisingly) get exponentially worse. Although microwaves dont (seem) to affect humans much at the intensities we're talking about, they do have a habit of frying the hell out of anything electronic. Anything passing through that beam (which incidentally will be invisible, and moving at about 1000mph with respect to the earth's surface) will have it's electronics damaged or destroyed. This includes watches, pacemakers, cars, buildings and passenger jets.

Although the technology certainly is viable, the question is it's practicality. For such a station to ever be allowed, there would have to be a permanent moon-based maintenance crew (or several), to prevent what I have just described. This would multiply the costs by a hundred, as humans permanently on the moon need food, water, entertainment and shift changes. You cant exactly car-pool a quarter of a million miles. There will always be public opposition to any remote, unmanned facility beaming energy directly to earth - too much can go wrong. It conjures up old images of laser death rays from space ala Independence Day. Really what the world needs to do is stop using so much energy, but try telling that to the guy with the shiny new PC.

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