Using Modeling All Alternatives to explore 55% decarbonization scenarios of the European electricity sector.

Climate change mitigation is a global challenge that, however, needs to be resolved by national-level authorities, resembling a "tragedy of the commons". This paradox is reflected at the European scale, as climate commitments are made by the EU collectively, but implementation is the responsibility of individual Member States. Here, we investigate a suite of near-optimal effort-sharing scenarios where the European electricity sector is decarbonized between 55% and 75% relative to 1990, in line with 2030 ambitions. To this end, we use a brownfield electricity system optimization model in combination with the Modeling All Alternatives methodology. Results show that only very particular effort-sharing schemes are able to reach the theoretical minimum system cost. In most cases, an additional cost of at least 5% is incurred. Results reveal large inequalities in the efforts required to decarbonize national electricity sectors.