Abstract
Moving beyond the combination of adoption subsidies, standards, and (albeit limited) attempts at carbon pricing that largely characterized US climate policy over the past decade, recent climate-related legislation has transformed not only the scale of US climate activities but also the policy mechanisms adopted. Newly scaled policy instruments—including demonstration projects, loan guarantees, green banks, and regional technology hubs—are motivated not only by unpriced carbon externalities but also by innovation market failures. This paper maps the economics literature on innovation market failures and other frictions to the stated goals of these policy instruments, with the goal of focusing discussions about how to implement these policies as effectively as possible. The paper also discusses how program evaluation can help to illuminate which market failures are most relevant in a particular context and which policy instruments are most targeted to them.