Correction on solar power info page

Your organization provides a lot of useful information about renewable
energy technologies - congratulations!

However, on the solar power introduction page:
http://solstice.crest.org/solar/solar_intro.html

while there is a lot of good and accurate information there, the
one question:

Why don't we build a solar plant on the moon and beam the
energy back to Earth?

has an answer that is completely incorrect. "Beaming" electricity
is in fact perfectly feasible, has been demonstrated on a small
scale, and has been discussed extensively by physicists and engineers
for decades; there is no real mystery about it. It is in fact the
same process used by communications satellites to send information encoded
in electromagnetic energy to Earth, but with a tighter beam to allow
full capture of the beamed power.

Just as with communications satellites, the reason information is
not "beamed" around the world is a line-of-sight issue: you can
"beam" signals from a tall tower or mountain to surrounding areas,
but the Earth's curvature prevents information beaming over any
great distance. But via a satellite, we can beam information to
anywhere on the planet. The same process applies for beaming power.

The correct answer to your question is, again, economic. Building
solar plants on the Moon requires a huge capital expenditure and
launch of many thousands of tons of equipment; overall costs might
end up as low as the $2 to $3/Watt of ground-based solar systems,
but the minimum scale for an economic plant is on the order of
one hundred GigaWatts, so 200 to 300 billion dollars in capital
expense. Nobody's willing to put up that money for a system with
so many unknowns at this time.

If launch costs to space were lower (and there is some hope that
advances in private markets will bring down costs by a factor of
5 to 10 over the next decade) then in-orbit power satellites become
economical at the 1 to 2 GW scale; these could be built for less
than $10 billion, and are in a range that may be feasible for utility
development. But orbital launch costs have to drop significantly
first; perhaps the potential market for solar power systems in space
could be a motivator for that process, but it is all quite uncertain
at this time.

I can provide a large number of scientific references on this subject
if you are interested. See for example the following articles:

* "Solar power via the moon", David Criswell, The Industrial Physicist,
Volume 8, Number 2, p. 12, (April/May 2002) http://www.aip.org/tip/0402.html

* "Advanced Technology Paths to Global Climate Stability: Energy for a
Greenhouse Planet", M. Hoffert et al., Science Vol. 298, p. 981 (2002).

* "Laying the Foundation for Space Solar Power: An Assessment of NASA's
Space Solar Power Investment Strategy" (2001)
http://www.nap.edu/execsumm/0309075971.html

* "The Case for Space Based Solar Power Development", Arthur Smith,
August 2003: http://www.spacedaily.com/news/ssp-03b.html

Arthur Smith, PhD
President, Long Island Space Society