[en] This report provides an independent and forward-looking assessment of EU's energy infrastructure needs in order to support its global energy ambitions. In order to better understand the role of energy infrastructure and to obtain insights into about the investment challenge Europe faces, we have aimed at optimising the level of infrastructure for several sets of assumptions. This study is based on a joint power-gas-hydrogen model inspired by the LTS 1.5TECH scenario. The simulations have been performed with Artelys Crystal Super Grid, a multi-energy modelling solution enabling joint power-gas-hydrogen simulations with an hourly time resolution and investment optimisation in infrastructure and flexibility solutions. The interlinkages between countries is explicitly modelled for electricity, methane and hydrogen, and the investments in new infrastructure and repurposing of methane pipelines are optimised. In order to assess the robustness of our conclusions, sensitivity analyses have been undertaken to explore the role of key assumptions: hydrogen demand levels, RES localisation, biomethane production and technology choices for space heating. The key findings can be translated into recommendations for the revision of the TEN-E regulation: Given the magnitude of the investment challenge, procedures (e.g. related to permitting) should be streamlined and simplified; Scenarios and guidelines for cost-benefit analysis should favour a consistent deployment of renewable technologies and hydrogen consumption centres in order to avoid unnecessary investments in pipes and wires; The assessment of system needs at the 2050 horizon should be conducted jointly for the electricity and gas systems (including an explicit distinction between hydrogen and methane); There is no need for additional investments in methane infrastructure to ensure security of supply within the EU. Further investments in CH₄ infrastructure should be ruled out so as to avoid creating stranded assets, unless they set forward the repurposing of existing pipelines in line with demonstrated future hydrogen needs.