Renewable fuels for hard-to-abate transportation: Exploring the impact of biomass availability and variable renewable potentials

Decarbonising the hard-to-abate maritime and aviation transport sectors will be challenging. Alternative renewable fuels, such as biofuels and E-fuels, show promising potential for substituting traditional fossil fuels, but carry challenges regarding the expansion of variable renewable energy (VRE) and the availability of sustainable biomass. This study assesses these challenges and regional impacts using a comprehensive sector-coupled energy system modelling framework applied to Europe. Under high biomass availability, a documented substitution effect allows the share of E-kerosene and biokerosene to shift with VRE accessibility, whereas this flexibility declines under biomass scarcity. These differences are reflected in fuel costs: aviation fuel prices are more sensitive to biomass scarcity, while maritime fuel prices are more sensitive to VRE restrictions. Regional resource availability reshapes renewable fuel production and trade. Under the modelling assumptions, accessible VRE resources favour E-fuel supply-chains from Spain, while lower VRE accessibility increases the role of biomass-rich countries, including Germany and Poland, as exporters. Constrained VRE deployment results in increased infrastructure needs, lowers average renewable capacity factors, and raises total system costs by up to 9%. Finally, increasing scarcity increases the importance of carbon management. Biomass is prioritised for fuel production and industrial applications coupled with carbon capture, while direct air capture and carbon reuse become increasingly important for meeting fuel demand. These results highlight the need for coordinated policies on biomass utilisation, VRE deployment, carbon management, and infrastructure planning to achieve cost-efficient decarbonisation of Europe's hard-to-abate transport sectors.