The European Maritime Safety Agency has published research examining biodiesel blends with conventional marine bunker fuels as potential marine pollutants, addressing gaps in knowledge about spill response measures as the shipping industry transitions to alternative fuels.

The study, conducted jointly by the World Maritime University and French response organisation Cedre, focuses on blends based on fatty acid methyl esters (FAME), hydrotreated vegetable oil (HVO) and Fischer-Tropsch fuels. The final report was dated December 2025.

According to EMSA, biodiesel blends such as B20, B30 and B50 — used with marine gas oil or very low sulphur fuel oil — represent a near-term solution compatible with existing marine engines and infrastructure, enabling emissions reductions without requiring major technical modifications.

However, the agency noted that the behaviour of these blends as marine pollutants and the suitability of existing response measures for accidental spills are not yet comprehensively documented.

The research team, led by Anish Arvind Hebbar and including Stéphane Le Floch, Ronan Jézéquel and others from WMU and Cedre, conducted experimental recovery tests to provide evidence-based assessment of spill response techniques.

The study examined physicochemical properties of biodiesel blends, including viscosity, density, evaporation rates and water content. Testing covered the evolution of B30 FAME/VLSFO and B30 HVO/VLSFO blends under various weathering conditions, as well as their dispersibility and adhesion to oleophilic surfaces.

Recovery tests evaluated multiple response techniques including aerial surveillance, in situ burning, chemical dispersion, containment and recovery systems, surface nets and trawls, and sorbents. The research assessed the effectiveness of various skimmer types on fresh and emulsified biodiesel blends.

The regulatory review identified gaps in existing International Maritime Organization regulations, including MARPOL Annex I and II, regarding biodiesel blend classification and spill response frameworks. The analysis also highlighted deficiencies in ISO and ASTM technical standards, operational preparedness among oil spill response organisations, and training programmes.

The study examined biodegradation rates of FAME compounds in marine environments through GC/MS chromatogram analysis, tracking the evolution of bioluminescence and polycyclic aromatic hydrocarbon concentrations in water samples.

According to the research, biodiesel blend sales have increased in the ports of Rotterdam and Singapore, with the study documenting bunkering trials conducted between 2022 and 2024.

The report includes recommendations for developing legal frameworks to clarify fuel classification, expanding technical standards, updating operational manuals and training, and conducting further research on the environmental fate and behaviour of biodiesel blends.

EMSA stated the study aims to support the maritime sector by strengthening spill contingency planning, preparedness and response as the transition to alternative fuels accelerates.