Comparing sustainable fuel adoption in the energy transition for maritime and aviation transport

Maritime and aviation transport are widely recognised as sectors where reducing greenhouse gas emissions is particularly challenging due to their reliance on energy-dense fuels and the challenges associated with direct electrification. These sectors face increasing pressure to defossilise and reduce emissions in line with global climate goals, while simultaneously facing unique technological, operational, and economic uncertainties. This study addresses a key research gap by comparing the maritime and aviation sectors for common factors and sector-specific differences in their transition to green e-fuels produced from renewable electricity and sustainable CO₂. A techno-economic assessment is conducted to evaluate alternative fuel and propulsion options using the levelised cost of mobility framework. The analysis also incorporates the pricing of non-CO₂ greenhouse gases and air pollutant emissions. Results show that e-ammonia or e-LNG combustion is the most cost-effective option for maritime transport, when emission costs are excluded, whereas hydrogen fuel cells become more economical when these costs are internalised. In aviation, e-kerosene use in conventional aircraft presents the lowest costs, regardless of the year or emission pricing. The findings highlight the importance of considering unique characteristics of each sector and tailored defossilisation and decarbonisation strategies that consider sector-specific constraints. To sustainably meet the growing demand for transport fuels, rapid investments in renewable electricity generation, electrolysers, and e-fuel synthesis are essential. Development of strong regulatory frameworks and financial instruments will be critical to support early deployment of e-fuels and minimise the risks.