This study, commissioned by the European Parliament’s Policy Department for Citizens’ Rights and Constitutional Affairs at the request of the AFCO Committee, considers the legal space for an EU Climate and Energy Union. It assesses the major limits at the EU and national level, as well as the question if (informal) Treaty change is possible and necessary to create the space needed. It also assesses if an individual right to clean energy exists, or can and should be legally construed. It pays special attention to the challenge of funding and the role that the emerging principle of solidarity might play.