TCS Daily

Serious Solar Power

By Kenneth Silber - May 30, 2002 12:00 AM

It has become increasingly clear that solar power can play only a limited role in solving the world's energy problems - if the solar energy is collected on Earth. But there is an alternative that has received less attention than it deserves, including (indeed especially) from environmentalists. That alternative is space solar power, in which the sun's energy is collected by satellites or on the moon and then transmitted for use on Earth.

The idea has been around for several decades. In 1968, Peter E. Glaser of Arthur D. Little Inc. sketched out the concept of solar power satellites in an article in Science magazine. Glaser envisioned vast arrays in orbit that would collect solar energy, unimpeded by the atmosphere, and beam it to ground antennas in the form of microwaves. Unlike terrestrial solar arrays, such satellites could collect energy 24 hours a day and regardless of weather.

A second approach is lunar solar power, in which the solar arrays are placed on the surface of the moon. This idea has been developed by advocates such as physicist David R. Criswell of Houston's Institute for Space Systems Operations. A chief advantage of lunar solar power is that it limits the amount of material that must be launched from Earth; the solar arrays would be constructed, in substantial part, from lunar materials.

Space solar power, whether in its satellite or lunar form, has the potential to generate pollution-free electricity on a scale suitable to the needs of an industrialized society. According to an estimate published by the Electric Power Research Institute, photovoltaic cells in geostationary orbit (22,300 miles up) would collect about eight times as much sunlight as they would on Earth's surface. Moreover, space solar arrays would eliminate the environmental and esthetic blight of covering vast tracts of land with solar panels.

The technological and economic hurdles are high, however. Space solar power would involve assembling structures in space far larger than the International Space Station. (In the case of lunar solar power, it would also likely involve permanent human bases on the moon.) Moreover, launch costs must be reduced sharply for space solar power to be commercially competitive. A solar power satellite built and launched with today's technology would produce electricity at costs perhaps 10 times greater than what most electricity costs today. But this economic picture could change drastically in the coming decades, due to technological improvements (including cheaper launch vehicles serving various commercial purposes) and an expected burgeoning of global electricity demand.

For space solar power to become a reality, however, there will need to be significant research and development efforts by government and industry. (Government might have to play a major role in the early phases, since commercial viability is decades away.) Space solar power has been the subject of numerous studies and conferences, and attention has grown since the mid-1990s.

Yet U.S.-based activity has been limited mainly to conceptual analyses, and neither NASA nor the Energy Department has put substantial funds into research. (By contrast, the Energy Department spends hundreds of millions of dollars per year trying to develop another long-term energy prospect, nuclear fusion.) A more focused effort in space solar power has emerged in energy-poor Japan, where the National Space Development Agency seeks to place an experimental solar power satellite in orbit later this decade.

Space advocacy groups, and a few politicians such as Rep. Dana Rohrabacher (R.-Calif.), have pressed for stepped-up efforts in space solar power. Space enthusiasts note that the technology, besides addressing some energy and environmental needs, would give new momentum to the space program and spur the development of solar-powered spacecraft. However, popular support for space solar power has been limited - in major part, no doubt, because a very large portion of the public has never heard of space solar power.

The environmental lobby, which has long been quite vocal in advocating terrestrial solar power, has shown a general lack of interest in space solar power. A lack of awareness of the subject may be much of the reason. Still, it seems likely that, if space solar power projects were to move closer to reality, there would be a great deal of opposition from environmentalists worried about the supposed health effects of microwave beaming (or that the low-intensity beams could somehow be used as military weapons).

The long-term possibility of space solar power today presents an interesting challenge, and opportunity, for environmental groups. Environmentalists who have a broad dislike of technology (or space exploration or any kind of large-scale industry) will likely refrain from advocating or even analyzing space solar power. However, there may be many environmentalists who are serious about using solar energy on a large scale, to power an industrialized society. They should start thinking beyond the confines of this planet.

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