III. ABOUT THE ENVIRONMENTAL EFFECTS III.I A prominent concern is the microwave bio-effects of the SPS power transmission system. What happens to people and ecosystems outside the rectenna site should control of beam directionality be lost? Microwave power densities have been calculated for the case of total failure of the phase control system.27 if the uplink pilot beam transmitter at the rectenna is shut off, for example, the sub-arrays on the satellite antenna will no longer be phased together and the total beam will be defocused. The peak intensity of the beam at ground level drops to 0.003 mW/cm^ and the beam width greatly increases. The power density of a defocused beam is less than the ambient level for television transmissions within the average city and is significantly less than the U.S. and the U.S.S.R. guidelines (10 and 0.01 mW/cnr respectively). Under normal operations, the general population and off-site ecosystems would be exposed to power densities ranging from 100 to 100,000 times below the U.S. standard limit (up to 100 times below the U.S.S.R. standard limit). Preliminary investigations in several priority areas <e.g., immunology and hematology, mutagenesis, carcinogenesis, reproduction, teratology and growth) reveal no expectation of impairment of the general population or animal and avian members of ecosystems outside the rectenna site.28 Further investigations are planned in these and other areas. For example, a very extensive experiment to study the effect of low-level microwave radiation on the European honey bee has been conducted at the University of California at Davis. The results are now under analysis and a report is expected in the near future. Should a second pilot beam be set up (e.g., by terrorists) to re-direct the beam, the beam will also defocus. This is a failsafe feature of the phasing system. In addition, the rectenna design includes sensors to detect any large changes to incident power density; this information would immediately be transmitted to the antenna to cease operations.27 III.2 What are the atmospheric heating effects of decentralized solar energy systems compared to the SPS? All of the waste heat generated by decentralized solar energy systems on earth would be dissipated in the atmosphere near the earth's surface. The amount of waste heat would depend upon the size and design features of individual systems. Undesirable effects produced by this waste heat would depend upon the characteristics of the environmental surroundings. Technical information on the microwave power transmission system is taken from the SPS Reference System Report, #D0E/ER-0023, October 1978, pp. 30,33, 45 28Briefing by John Allis of EPA on SPS Microwave Bioeffects Studies, presented at a June 1979 SPS Review in Washington, D. C.
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