Online Journal of Space Communication


Successfully implementing a Solar Power Satellite Program will take a multi-discipline, multi-national, geopolitical effort. Planning for that level of complexity must begin now. This article gives the principal reasons for going to space for "free power," and seeks to illustrate some of that complexity. Solar energy is "free", just like the water in a hydroelectric system. There is no cost for fuel.

The sun delivers energy to earth at the rate of 1.37 kilowatts per square meter during daylight hours. This amounts to 174 petawatts (one petawatt is 10 to the fifteenth power). About 89 petawatts reach the earth's surface. A satellite positioned in geosynchronous orbit at approximately 22,300 miles above earth (with an area of solar cells of 10 kilometers squared) will be bombarded by 13.7 gigawatts with only brief blackouts twice a year. With cell conversion efficiencies of only 10%, the electricity potentially produced will be 10 gigawatts delivered to the space-based microwave transmitter; somewhat less will be delivered to the receiver and relayed into the modified power distribution networks located near the user on earth.

Not one but several gigawatt-satellites will be required to generate the power needed over the next twenty to twenty five years. The continuing degradation of the environment accelerated by population growth, our inadequate efforts to balance carbon-based fuels with those from "green" sources and the increasing worldwide gross national product is good reason to get started with a program of energy from space.



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