Energy System Implications of Demand Scenarios and Supply Strategies for Renewable Transportation Fuels

Abstract

Transport sector greenhouse gas (GHG) emission reduction is among the hardest challenges in transforming energy systems to zero emissions. Its energy demands stem from an interplay of social behavioral, technical factors, political decisions and economic conditions. This necessitates detailed sub-sector demand modeling to scrutinize the evidence base of energy planning. Energy supply of climate neutral transportation services is expected to challenge electricity supply infrastructure expansion. Additionally, studies assume large shares of imported gaseous and liquid energy carriers and proclaim global renewable fuel import potentials mostly neglecting local societies' needs without sufficiently justifying this premise. Simultaneously, sustainable biofuels' impacts on required electricity supply infrastructure is yet not very well understood. Combining bottom-up and top-down energy modeling approaches, we address recent shortcomings designing a set of eight scenarios varying in climate ambition, the share of indirect electrification of transport final energy demand, and biofuel availability. We find that bottom-up demand modeling of transport final energy demand significantly narrows down ranges of top-down-assumed renewable fuel energy demands. Higher hydrogen and derivative fuel demands do not affect renewable energy capacity expansion, moderately impact grid expansion and largely influence electrolysis (75-150~GW) and fuel production capacities (7-10~GW/a). Biofuel availability may significantly reduce e-fuel demand, which reduces high energy infrastructure expansion gradients, distributing renewable energy expansions across the next 25 years, significantly reducing cost-optimal hydrogen production capacity in the medium term and necessary grid expansion within Germany beyond 2030. Although we focus on Germany, the lessons learned here can be applied to other regions of the world.

Keywords: Energy system analysis, transport sector, synthetic fuels, biofuels, fuel imports