Investigation of Equatorial Medium Earth Orbits for Space Solar Power

Most existing space solar power concepts place one or more power stations in geosynchronous Earth orbit (GEO). However, due to the limited availability of GEO orbital slots, it may not be feasible to locate a power station in GEO. To overcome this limitation, this article presents a system analysis for a space solar power system that incorporates a constellation of power stations in a 20184 km altitude equatorial medium Earth orbit (MEO). The orbiting power stations are based on the Caltech Space Solar Power Project architecture. The constellation consists of multiple power stations in a shared equatorial MEO each transmitting to a nonequatorial receiving station. The analysis assumes a one-to-one correspondence between the number of power stations and the number of ground stations. Like a GEO-based system, this constellation architecture enables a MEO-based system to provide near continuous power (outside of eclipse) to each ground station. It is shown that a MEO constellation with three or more power stations provides comparable transmission efficiency to a GEO-based system. The levelized cost of electricity (LCOE) is then computed for MEO systems with three, four, and five power stations and compared to the LCOE for the GEO-based system. Ground station area is identified as a significant contributor to the LCOE for the MEO-based systems. The system analysis shows that a MEO constellation with as few as four power stations has an LCOE comparable to GEO, and hence, it is concluded that MEO is a viable alternative to GEO for space solar power.