Cost comparisons of solar power satellites versus lunar based power systems

A comparison is made between projected electricity costs of an optimized space solar power station (SPS) in GEO and a moon-based SPS (LPS). A single SPS would receive sunlight on an almost uninterruptible basis. The LPS would be illumined 50 percent of the time, thus requiring two stations on opposite sides of the moon as well as three terrestrial rectennas spaced 120 deg apart. The 5 percent efficient LPS cells would be manufactured from lunar materials and built into arrays mounted on tall mounds. The steerable GEO SPS would have 15 percent efficient cells. Construction costs would be significantly lower on the moon, but the total antenna area would need to be two orders of magnitude larger to produce the same output as the SPS. It is estimated that the LPS would therefore deliver 5 GW electricity to earth stations at a cost of 511.3 mills/kW, compared to 46.8 mills/kW from the SPS. It is concluded that lunar materials are suitable for building an SPS, not a LPS.