The EU energy strategy is hard-poised to ensure energy security for the Union, mainly due to its fixation on fossil energy imports. This paper argues that energy security can holistically be addressed only in case sustainability becomes a priority goal. Such a re-conceptualisation does not only pave the way for a radical restructuring of the energy systems in Europe that can cater for the EU’s energy needs in a sustainable way, but also theorises energy as a scarce resource that hence should be highly priced. On the basis of a thorough ecological tax reform, energy prices can convey accurate signals to households and enterprises and allow for a smooth function of the economy that is today frequently upset by energy price hikes and slumps. The paper aims to make a timely contribution to the current debate on the shape and priorities of the Energy Union by making a strong case for a re-ordering of priorities in EU energy strategy.