Mirrors in Dawn Dusk Orbit for Low-Cost Terrestrial Solar Electric Power in the Evening
Herein, a constellation of mirror satellites in a dawn dusk polar orbit is desciibed with the mirrors deflecting sunbeams down to terrestrial solar electric power fields producing additional solar energy in the early morning and evening hours. A specific mirror satellite design is described where each satellite is comprised of a lightweight thin aluminized mirror membrane stretched flat by three radial spokes telescoping out from a central body. 'When deployed, each mirror satellite is about twice the size of the International Space Station (ISS). Control moment gyros similar to those used in the ISS are mounted inside the central body of the mirror satellite for attitude control and sunbeam pointing. The three spokes collapse and the mirror membrane is folded such that several of these mirror satellites can potentially be stowed inside the failing of either a SpaceX Falcon 9 or a Boeing Delta IV rocket for launch and deployment. If this dawn dusk mirror satellite constellation is implemented, the additional solar energy produced at the terrestrial solar fields can reduce the cost of solar electricity at the ground sites to less than 6 cents per kWh.
There are two problems limiting solar electric power. The amount of sunlight is limited and there is no sunlight during peak demand in the evening hours. Herein, we note that these problems can be addressed by placing light weight mirror (heliostat) satellite constellations in sun synchronous dawn to dusk low earth orbits in space at an altitude of 1000 km . These satellites can deflect sunbeams dawn to an array of solar power stations distributed near major population centers around the earth. These solar PV or trough C SP earth stations are already being built. If we assume that there can be 40 such stations generating 5 GW each ten years from now, then the solar energy available to these ground sites can be increased from an average of 7 kWh per sq m per day without the space mirrors to 12 kWh per sq m per day with the space mirrors. The additional 5 kWh per sq m per day will be provided in the early morning and evening hours. See Fig. 1. The additional solar energy can reduce the cost of solar electricity at the ground sites to less than 6 cents per kWh. We shall explore this big and challenging idea here.