Seite - 117 - in Water, Energy, and Environment - A Primer

the rectenna, but presumably amicrowave frequencywould be chosen with minimal atmospheric absorption. It should also be noted that every step of SPS technology is technically feasible and well established – solar radiation conversion to electricity, microwave generation, microwave transmission through air, microwave collection and conversion to electricity, andgrid transmission. What are the arguments against SPS? • Putting anything into orbit is expensive, and until these costs are reduced significantly SPS will not be cost competitive. • Economicsdictatethat largeindividualSPSunits(hundreds to thousands of megawatts) be placed in orbit. One suggestionwas to place a 10GWunit in geosynchronous orbit to supply the electrical needs of NewYork City. In myopinion this is highly problematic since youwould be putting all your eggs in one highly vulnerable basket. (These vulnerabilities include exposure in space to higher-than-usual levels of damaging radiationwhichwill shorten expected equipment lifetimes; the possibility of collisionswithmicrometeorites and space debris; ordinary technical failures with a large amount of electricity potentially at risk; and vulnerability to sabotage/attack in the event of international tensions). • Aircraft will need to avoid the beams passing through the atmosphere to avoid any possible impacts on humans from exposure to relatively high-strength microwave signals.Birds are another potentially impacted species. • The large land areas required for rectennas which would ideally be located in close proximity to cities with large electricity demand. It is therefore reasonable to ask: isSSPaviableoption for future electricity supply? Inmy opinion, not in the near- tomid-term. Long-termmay be a more optimistic story. Solar PV costs are Renewableenergy 117