Navigating the IMO's new greenhouse gas fuel intensity (GFI) regulation: A fleet-based analysis of compliance strategies

This study provides, to the best of our knowledge, one of the first fleet-level empirical assessments of the operational and economic implications of the International Maritime Organization's (IMO) newly introduced Greenhouse Gas Fuel Intensity (GFI) regulation. Using a well-to-wake life cycle assessment framework, the analysis evaluates four similarly sized container vessels operating within the same fleet. Conventional fuels, heavy fuel oil and marine diesel oil, are compared with alternative options, including hydrotreated vegetable oil, fatty acid methyl esters, green hydrogen, and green ammonia, with respect to GFI compliance, regulatory penalties, and fuel costs. To capture the influence of regulatory stringency, penalty cost scenarios are examined. Beyond vessel-level analysis, the study introduces and evaluates an intra-fleet GFI credit transfer mechanism, assessing its potential to support strategic compliance management across ships. The results reveal a divergence between environmental and economic performance. Green ammonia exhibits the lowest greenhouse gas intensity, while conventional fuels remain the most economically attractive option at the individual vessel level. However, under a fleet-wide credit transfer strategy, converting a single vessel to green ammonia can generate sufficient compliance surplus to offset the deficits of up to three conventionally fueled ships during the 2028–2032 period. Beyond 2033, as GFI targets become more stringent, ammonia emerges as the most effective fleet-level compliance option. Sensitivity analysis confirms robustness across key parameters. Overall, the findings demonstrate the feasibility of a phased compliance strategy that balances environmental objectives with economic considerations, offering shipowners practical guidance for navigating the implementation of the GFI regulation.