To achieve the deep decarbonization goals of Paris agreement, France has set a zero net CO2 emissions target by 2050. This ambitious target can only be achieved by massive reduction of fossil fuels' share in the primary energy supply side. While the energy mix for different sectors has been studied abundantly in the literature, less studies have dealt with the impact of sector-coupling in deep decarbonization goal.

To this end, we develop a detailed model of French energy sector, leaving the vector choice for different sectorial end-use demands endogenous. 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 (SCC) in reaching an optimal carbon neutral or negative CO2 emitting energy mix of France in 2050.

Our results show that (1) a nearly carbon neutral energy sector can be reached for a SCC value of 200€/tCO2, in case of availability of renewable gas, (2) and without renewable gas even a SCC of 500€/tCO2 can't lead to a carbon neutral energy sector. (3) While for a zero SCC fossil gas dominates the primary energy production, for a SCC value as low as 100€/tCO2 renewables become the main source of the primary energy supply and the share of renewable energy can reach up to more than 80% of the primary energy supply. (4) Unlike the existing literature, we find that a very big proportion of transport demand is satisfied by gas-powered internal combustion engine vehicles and the share of electric vehicles in the final light transport demand never exceeds 9%. (5) While the existing heat network in France accounts for a very small proportion of heat demand, our findings suggest that central heat pumps can play an important role to satisfy heat demand in regions with high population density. (6) For social cost of carbon values of more than 100€/tCO2, the heat sector is fully electrified by individual and central heat pumps.

This study suggests further development of gas charging network (for transport end-use) and heat network. Another central suggestion of this study is to invest in renewable electricity and gas production technologies, as well as negative emission technologies to reach climate goals in cost-optimal ways.