The European energy market remains heavily reliant on imported fossil fuels and fragmented across Member States. This leaves the EU exposed to high and volatile energy prices, posing risks to its growth outlook and its international competitiveness. As the EU advances its energy security and climate neutrality objectives, the role of electricity and renewable energy is set to increase at the expense of fossil fuels. This paper argues that achieving a genuine European Energy Union would help to reach these goals and identifies five key policy priorities to support this process: strengthening cross-border infrastructure; mobilising innovative green finance; investing in tools to support flexibility and matching of supply and demand; improving the efficiency and harmonisation of energy taxation; and establishing a coherent industrial policy for clean tech.