Environmental Engineering Reference
In-Depth Information
generation in Granada, Spain, provided progress reports from groups
in Europe, the U.S., and Japan who are working on concepts and plans
for building solar power plants in orbit that would beam power down
for use on Earth. These concepts including building parts of the Solar
Power Satellite from lunar and asteroidal materials while the confer-
ence focused the technological and political developments required to
construct and employ a multi-gigawatt power satellite. It provided per-
spectives on the cost savings achieved by using extraterrestrial materials
in the construction of the satellite. There were proposals and feasibility
studies of lunar and high-orbital solar power stations, including assess-
ments of the cost factors.
Power from space using solar power satellites would reduce reli-
ance on burning hydrocarbons and would be one solution to our future
energy needs. The Sun is constantly sending energy to the Earth. Any
point on land is in the dark half of the time and during the day clouds
can also block sunlight and power production. In orbit, a solar power
satellite would be above the atmosphere and could be positioned so that
it received almost constant direct sunlight.
There is no air in space, so the satellites receive intense sunlight,
unaffected by weather. In a geosynchronous orbit an SPS would be illu-
minated over 99% of the time. The SPS would be in Earth's shadow for a
few days at the spring and fall equinoxes. This would be for a maximum
of an hour and a half late at night when power demands are at their low-
In many ways, the SPS is simpler than most power systems on
Earth. This includes the structure needed which in orbit can be consider-
ably lighter due to the lack of weight.
Some early studies considered solar furnaces to drive convention-
al turbines, but as the efficiency of the solar cell improved, this concept
seemed less practical.
Another advantage is that waste heat is re-radiated back into space,
instead of warming the biosphere as occurs with conventional sources.
Some energy is lost in transmitting power to stations on the Earth, but this
would not offset the advantages of an orbiting solar power station over
ground based solar collectors.
The concepts of solar power satellites were being worked on in the
1960s, but there were a number of problems impeding them. The SPS con-
cept was considered impractical due to the lack of an efficient method of
sending the power down to the Earth for use. This changed in 1974 when
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