This study is a review of current EU energy policy and its implementation, in order to determine the lessons that can be learned in terms of developing an energy policy that meets the objective of sustainability (i.e. meeting the CO2 reduction targets set in the light of the EU’s Paris commitments) but at the same time delivers on competitiveness (generating competitive prices and creating jobs, fairness (ensuring fair prices for citizens and sharing fairly any burden between citizens across the EU) as well as energy security. In addition, the role of energy technologies has been analysed across different energy scenarios aiming at complying with Paris agreement targets and supported by detailed modelling. Having verified the discrepancies of these energy scenarios in terms of technological decarbonisation potential and needed investments, we provide evidence of the future costs of certain strategic energy technologies towards a cost-effective EU decarbonisation. In particular, we focus on the future costs of renewable electricity and hydrogen technologies. We first analysed the potential future uses of electricity and hydrogen across scenarios and then the assumptions on future costs of these technologies (e.g. levelized costs, technical potential), drawing conclusions on their cost-competitiveness and on the need for further policy support.