Carbon-neutral future with sector-coupling; relative role of different mitigation options in energy sector

Many studies have analyzed the energy mix at national and continental scales, suggesting different low-carbon mixes for future energy systems. While there is abundant literature on the energy mix for different sectors, fewer studies deal with achieving the goal of deep decarbonization using sector-coupling. Moreover, they suffer from limited representation of emerging low-carbon options and incomplete coverage of the main energy sectors. We develop an integrated optimization of dispatch and investment model for the whole energy sector, enabling full sector-coupling and applying this model to the French energy system we study the synergies of sector-coupling among different energy vectors, as well as the role of each low-carbon energy supply technology and the impact of the social cost of carbon in reaching an optimal carbon-neutral or negative CO2-emitting energy mix of France in 2050. Our results suggest that a social cost of carbon of 200 euros/tCO2 will achieve carbon-neutrality, and accounting for unfavorable future conditions, 300 euros/tCO2 can assure this target. In the presence of the social cost of carbon renewables become the main source of the primary energy supply (up to more than 80% of the primary energy supply). Exclusion of nuclear energy from the energy supply side has a minor impact on both emission reduction and cost-optimality. A fully electrified heat sector and a highly gas-dependent transport sector fueled with renewable gas help reaching carbon-neutrality at the lowest cost.