Environmental Engineering Reference
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scale, since the antenna can be obtained at nearly constant mass just by spacingmore
widely a
fixed number of elements. Although the transmitter element mass is not
known to us, it may well amount to the 4
10
6
kg mass we just obtained. This rough
10
6
estimate can be presented as 1GW/(4
240W/kg.
For comparison, an estimate of the mass of a 4 GW space station as 80 000
tons
þ
168 000) kg
¼
10
6
kg has been presented (http://en.wikipedia.org/wiki/Space-base-
d_solar_power.) corresponding to 50W/kg. This mass is larger in part because it
assumed conventional solar panels, not thin-
lm solar cells.
Our estimates suggest that the mass of one power satellite to deliver 1GW to areas
on earth, the size of two football
fields, is at least 10 times the mass of the
International Space Station. If we take the cost as proportional to mass, then the
cost of the proposed 1GW power satellite is at least 10 times the cost of the ISS,
10
¼
80
$135 billion, with cost at least $1350/W. This is a thousand times more
expensive than solar power on earth, wind power on earth, or a conventional coal-
or gas-powered electrical plant. In fact, a constellation of at least four such satellites
would be needed to extend the 2 h above a given location to the peak power of the
working day. If four were in orbit, then any part of the country could obtain power but
the total power available would still only be 4GW.
From an entrepreneurial viewpoint, there may be organizations willing to pay
much higher prices for reliable electrical power literally at the ends of the earth.
Power could be in this way reliably be provided at the poles of the earth, anywhere at
sea, or in remote mountainous locations to support perhaps drilling or mining
operations. The polar regions of the earth are much easier to colonize than the moon,
and interested groupsmight
nd solar power beamed from the sky a reason to build a
colony at the South Pole. The military might use this as they have used the global
positioning system (GPS): it is dif
cult to protect oil tanker trucks from harassment
by even a minimally equipped group of determined attackers, while invisible power
from the sky would be hard to obstruct.
In the larger picture of world energy supply, all of these analyses mean that space power
satellites are not in any way economically competitive
.
A similar conclusion was reached by Dr. Simon Peter Worden (http://www.
thespaceshow.com/detail.asp?q
1127, http://www.nasa.gov/centers/ames/about/
centerdirector.html.) (Brigadier General, USAF, retd.), Director of the NASA Ames
Research Center (ARC), who stated on March 23, 2009, Space based solar power is
about 5 orders of magnitude more expensive than solar power in the Arizona desert.
This is an estimate of $10
5
/W. Dr.Worden cited the high cost of puttingmaterials into
orbit.
¼
