Electricity is a key area in climate mitigation. The sector needs to significantly expand while transitioning to renewable production, all in an extremely short timeframe. This paper focuses on ownership and control in the electricity sector in an era of climate change. Borrowing substantially from classical American Institutionalism, heterodox theories and histories of the firm, and legal institutionalism, this paper discusses the historically constituted nature of the categories of property, capital, and the firm and how these literatures provide helpful frameworks for analyzing the recent history and possible futures of electricity sectors. A short discussion of the recent history of the German electricity sector, particularly the large utility RWE, will briefly illustrate the approach. Demands of warming mitigation will require revised notions of ownership and an updated theory of the firm, property, and corporate governance for the Anthropocene.