This article provides a review and methodological critique of recent influential "first-generation" government-sponsored studies seeking to derive monetary values for the environmental effects of electricity supply technologies. It is observed that environmental valuation suffers from many of the general methodological difficulties faced by other quantitative appraisal techniques. In addition, environmental valuation is found to present its own specific methodological difficulties and theoretical problems. The practical policy efficacy of environmental results is called into question. It is concluded that there exist alternative approaches to the social appraisal of the environmental impacts of generating technologies that warrant greater attention to further development than does environmental valuation.