Near-Millimeter Wave Issues for a Space Power Grid

This paper reports continuing work on an evolutionary revenue-generating approach to Space Solar Power. The 220 GHz atmospheric transmission window is chosen, leaving open the option of using millimeter wave or laser wavelengths. The progression from frequency to system business case is laid out, seeking the performance figures needed for a self-sustaining system and to open up Space Solar Power in 15 to 17 years from first launch. An overall transmission efficiency in excess of 30 percent is required, from DC to beamed power and back to DC or high-voltage AC, to meet a delivered free-market price target of 30 cents per KVM, or 20 percent if a price of 45 cents per KWH. Climate data show that rain obscuration is a non-issue for many of the renewable-power sites that comprise the market. The technology of direct solar conversion to DC and to beamed power would satisfy the needed efficiencies but requires advances in nano-scale fabrication with dielectrics.