Energy system implications of demand scenarios and supply strategies for renewable transportation fuels

Reducing greenhouse gas emissions in the transport sector is among the hardest challenges in transforming energy systems to zero emissions. Transport energy demands are driven by an interplay of social behavioral, technical factors, political decisions and economic conditions, motivating detailed transport demand modeling. In Germany, transport energy supply - increasingly from electricity - is expected to challenge the energy supply infrastructure. Recent studies assume large shares of imported clean energy carriers and proclaim global renewable fuel import potentials. Simultaneously, sustainable biofuels' impacts on required electricity supply infrastructure is yet not well understood. We assess the impact of climate ambition, indirect electrification shares and biofuel availability on energy supply infrastructure in 8 demand scenarios. Coupling the European energy system model REMix with the biofuel allocation model BENOPTex, we calculate cost-minimal energy supply infrastructure for each scenario. This high detail of integrated transport sector and biofuel modeling is novel to energy system analysis. We find that incorporating user preferences in sales decisions clearly narrows the range of transport energy demand. As the German renewable energy potential is exhausted, higher clean fuel demand is covered by imports. Still, the use of these fuels drives the required power grid expansion, and especially electrolysis and fuel production capacities. Biofuel availability may significantly reduce e-fuel demand reducing cost-optimal hydrogen production capacity in the medium term and necessary grid expansion within Germany beyond 2030. The model outcome is limited by assumptions on costs and availability of import options. Future work should further address modal shift transport scenarios.