1.05.2009

Space Tech of the Week: Solar Power Satellite

What is it?: Large assemblage of solar cells in space that collect sunlight, convert it into electricity, then beam the electricity to receiving stations on Earth using microwave beams.

This technology was first invented by Peter Glaser in 1968 (for which he received a patent).
Today, all the technology needed to make this invention a reality already exists. The greatest challenge in building these mile long satellites is comparable to the challenge of constructing the International Space Station (i.e. lots of launches to haul the parts up and lots of spacewalks putting the pieces together). The microwave receiving stations on Earth could be built in unpopulated areas like deserts or on sea platforms (although they really could be built anywhere because the microwaves being sent down are not at dangerous levels. Read here for more info on this topic) . According to an opinion piece by
Ben Bova (president emeritus of the National Space Society and fiction/non-fiction author) the cost for building a full size satellite would be on the order of $1 billion. One of the main reasons for this high cost is the current cost of space launches. A technology demonstrator (such as the launch of just one operating piece) would be significantly cheaper. According to Bova a single full-size SPS could deliver 5 to 10 Gigawatts of energy to the ground continually (compare this to the total generation capacity of the state of California which today is 4.4 Gigawatts).

So what are the advantages of this technology?: From the extensive wikipedia article:

"The SPS concept is attractive because space has several major advantages over the Earth's surface for the collection of solar power. There is no air in space, so the collecting surfaces would receive much more intense sunlight, unaffected by weather. In geostationary orbit, an SPS would be illuminated over 99% of the time. The SPS would be in Earth's shadow on only a few days at the spring and fall equinoxes; and even then for a maximum of 75 minutes late at night when power demands are at their lowest. This characteristic of SPS based power generation systems to avoid the expensive storage facilities (eg, lakes behind dams, oil storage tanks, coal dumps, etc) necessary in many Earth-based power generation systems. Additionally, an SPS will have none of the polluting consequences of fossil fuel systems, nor the ecological problems resulting from many renewable or low impact power generation systems (eg, dam retention lakes).

Economically, an SPS deployment project would create many new jobs and contract opportunities for industry, which may have political implications in the country or region which undertakes the project. Certainly the energy from an SPS would reduce political tension resulting from unequal distribution of energy supplies (eg, oil, gas, etc). For nations on the equator, SPS provides an incentive to stabilise and a sustained opportunity to lease land for launch sites.

Developing the industrial capacity needed to construct and maintain one or more SPS systems would significantly reduce the cost of other space endeavours. For example, a manned Mars mission might only cost hundreds of millions, instead of tens of billions, if it can rely on an already existing capability."


Animation showing how it works (1:03):


Ad promoting this technology (4:29):


European Space Agency video discussing the technology (4:53):


1975 NASA Demonstration of high power long distance wireless power transmission (2:15):
Recently, a former NASA researcher was able to wirelessly transfer electricity 92 miles from one Hawaiian island to another (Read Wired article here). This distance is 100 times larger than the NASA demonstration seen above.

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