Introduction to solar electric power from space
It is extremely difficult to gather diffuse, irregular solar power on Earth and make it available as a dependable source of commercially competitive standalone power. The challenges increase as irregular terrestrial solar power becomes a larger fraction of total regional or global commercial electric power. Research indicates that terrestrial solar may provide 5% to 17% of renewable power to conventional small power grids. Fifty percent supply of power by terrestrial solar, and wind, is conceivable. However, an increasing fraction of renewable power is limited by the higher cost of renewable sources, high costs of storage and transmission of renewable power, institutional resistance, and regulator effects (Wan and Parsons, 1993).
Conversely, above the atmosphere of Earth and beyond Earth's cone of shadow the sunlight is constant. In space, very thin structures that would be destroyed by water vapor, oxygen, winds, and other hostile elements of Earth's biosphere, can be deployed, collect the dependable sunlight (1.35 GWs/km2 near Earth), and convert it to electric power. The electric power is then converted into microwave beams and directed to receivers on Earth at the relatively low intensity of —0.2 GWe/km2. Microwaves of — 12 cm wavelength, or —2.45 GHz, are proposed because they travel with negligible attenuation through the
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