How do discount rates for renewable and low-carbon electricity generation technologies differ, and what drives investors’ perceptions of the riskiness of these technologies? On behalf of the Committee on Climate Change, we investigated these and related questions. Taking into account technological, market, and policy risks, our analysis showed how discount rates for low-carbon generation technologies currently differ, and provided an outlook for how they might evolve. The analysis was based on a survey of investors, project sponsors and financial analysts, and the results were supplemented by a review of the literature and analysis of capital markets data.