This special section of New Political Economy demonstrates the value of critical environmental political economy for our understanding of energy, and possibilities for, just energy transformations. In the following essay, I identify key themes from the special issue papers addressing the political economy of decarbonisation strategies and potentially deeper green transformations in capitalist economies. These are: (1) the historicity of energy-society relations; (2) the crisis tendencies of energy capital; (3) the spatial re-configurations associated with energy transitions, and (4) the generative and contradictory dynamics of political contestation. By foregrounding these analytic themes, political economic analyses challenge much of the existing energy transition literature that describes fuel switches and technological innovation without thematising relations of power or the historical significance of capitalist eco-social relations of energy. In order to advance the critical political economy contributions to our understanding of energy transition, I discuss key analytic insights from this tradition into agency, structure, space and process.