New results from the EU-backed Project CLEANSHIP trials in Denmark have demonstrated that running a vessel on pure biodiesel can cut black carbon emissions by as much as 81 per cent compared with conventional marine gas oil. CLEANSHIP is led by the Danish Technological Institute and its partners, Uni-Tankers, Green Instruments A/S, the Maersk Mc-Kinney Møller Center for Zero Carbon Shipping, Danish Maritime, and Danish Shipping.
Black carbon has emerged as a priority pollutant for regulators and environmental groups as a short-lived but highly potent climate forcer that is particularly damaging in the Arctic, where deposited particles accelerate ice melt. It also has direct public health impacts through degraded air quality in coastal and port communities. Unlike CO2, reductions in black carbon deliver almost immediate climate benefits.
The CLEANSHIP data were gathered during normal commercial operations on the Uni-Tankers product tanker Falstria Swan. Over a three-day voyage, the vessel was operated on B100 FAME biodiesel and the results were compared with baseline measurements using marine gas oil. An advanced online sensor developed by Green Instruments in collaboration with the Danish Technological Institute enabled real-time tracking of black carbon emissions across different engine loads.
The findings point to particularly strong performance at low engine loads, where reductions of up to 81 per cent were observed. Even at higher loads, where combustion conditions are already more efficient, emissions were cut by around 61 per cent. For an industry accustomed to incremental improvements in air-pollutant control, the scale of the reduction is notable.
The results are scheduled for discussion at the IMO’s Sub-Committee on Pollution Prevention and Response in February. Black carbon is rising up the regulatory agenda, especially in relation to Arctic shipping, but the sector still lacks robust, real-world data on the performance of different fuels and technologies.
Biodiesel is already being used by several shipping groups to cut lifecycle greenhouse gas emissions, particularly under European carbon pricing and fuel-mandate regimes. The CLEANSHIP data show that the climate case is broader than carbon accounting alone and extends to local and regional environmental impacts.
The deployment of high-resolution, onboard sensors demonstrates that black carbon can be monitored with a level of precision that was previously difficult to achieve in operational settings. That capability will be essential if regulators decide to move towards formal reporting or control measures for soot emissions.
However, global production capacity remains small relative to the energy needs of the international fleet, and competition with road transport, aviation and industrial users is intensifying. Even under optimistic scenarios, biodiesel can only cover a fraction of shipping’s total fuel demand. Feedstock sustainability, price volatility and regional availability also remain unresolved issues.
