The Power and Transportation Future - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 273

Peter Glaser was granted a patent for his method of transmitting the pow-
er to Earth using microwaves from a small antenna on the satellite to a
much larger one on the ground, known as a rectenna. Glaser's work took
place at Arthur D. Little. NASA granted them a contract to lead four other
companies in a broader study in 1972. They found that while the concept
had several major problems, chiefly the expense of putting the required
materials in orbit and the lack of experience on projects of this scale in
space, it showed enough promise to merit further investigation and re-
search. Most major aerospace companies then became briefly involved in
some way, either under NASA grants or on their own. At the time the
needs for electricity were soaring, but when power use leveled off in the
1970s, the concept was shelved.
Recently the concept is of interest, due to increased energy demands
and costs. At some point the high construction costs of the SPS become fa-
vorable due to their low-cost delivery of power and the rising costs of elec-
tricity. Continued advances in material science and space transport reduce
the projected costs of the SPS.
Using solar panels on Earth is far less expensive, so much of the fo-
cus on solar energy is not on satellite systems. A major barrier is the high
cost of launching. A significant investment would be needed to get a so-
lar power satellite into orbit. Launch costs will need to come down before
generating solar power in space makes economic sense. There may not be
a financial reason to start building a solar power system unless we include
the environmental costs of our current non-renewable sources of energy. A
problem in opening any contemporary frontier is not usually a lack of en-
gineering imagination or insight, but a lack of capital to finance the initial
construction which makes the subsequent development possible.
A solar power system must also compete with other options which is
a challenge for all renewable energy solutions. Among the barriers hold-
ing back solar power satellites are a lack of political will and insight to
make the money available for further development.
There are also only a limited number of available slots in geosyn-
chronous orbit where a satellite would be able to continuously beam pow-
er to a specific receiver. In areas with plenty of sun and available land, sat-
ellites may not compete with generating solar power locally. There would
be more demand for beaming solar power to locations that couldn't gener-
ate it otherwise.
Some designs use solar arrays that are several kilometers long on each
side. The largest solar panels in space are being used on the International