A dispatching model based exploration of the post-nuclear phase-out Belgian energy mix

While a possible nuclear phase-out for the Belgian energy system has long been the subject of both political and societal debate, prevailing government policy at the beginning of 2021 is to enact a full nuclear phase-out by 2025. While the Belgian government is committed to the phase-out, an evaluation moment is foreseen by the end of 2021, where the final decision on the prospective nuclear phase-out will be made. This is the backdrop against which this paper uses a dispatching model, based on the urbs modelling framework, to estimate possible post-phase-out Belgian energy mixes. The obtained results show an increased reliance on gas-fired plants, or, if CO2 emissions are constrained to pre-phase-out levels, a marked increase in the amount of imported electricity and a fivefold increase in needed installed storage capacity. Total system costs increase as well, due to the additional storage required to allow for the increased penetration of renewable energy sources. These results show that there are important trade-offs between CO2 emissions reductions, energy independence and energy system costs which will have to be navigated after the Belgian nuclear phase-out. Although not a priori part of the scope of the research, the results highlight several signicant vectors for increased blackout risk, such as constrained electricity imports, the failure to realise the needed storage capacity explosion or transmission grid failures.