The environmental mid and long-term targets for the EU energy system are undoubtedly challenging. The aim of this study was to provide a quantitative policy assessment of what could happen if the transition of the transport and the power generation sector towards decarbonisation fails to progress as anticipated during the decade 2020-2030. The study considered policy and market failures which were related to the development of the recharging infrastructure, the rate of the technological progress and the availability of new alternative energy carriers during this decade. The study utilized the suite of PRIMES and PRIMES-TREMOVE models for the quantitative part of the analysis. The modelling analysis was based on the quantification of alternative scenarios and variants up to the 2050 horizon. The study scoped to emphasize to policy makers how critical the period 2020-2030 is for the transition of the energy and transport systems towards meeting the long-term climate objectives. Continuous policy intervention for the horizon up to 2030 was needed to mitigate the risk of market failures and to ensure the successful interplay between the relevant market actors.