The maritime industry has undertaken a range of tests exploring the use of biofuels, blending fats with diesel to create a more environmentally friendly transition fuel, with the latest test confirming the long-term operational feasibility of biodiesel. The results conducted using an NYK car and truck carrier (PCTC) further confirm the viability of the fuel.
DNV highlights the potential for biofuels in its new Maritime Outlook report. While it acknowledges the challenges over future availability, DNV notes that biofuel is easy to use. Its case study also showed that biofuel would be more economical for operators than paying the proposed penalties in the pending IMO regulations.
The Singapore-based Global Centre for Maritime Decarbonisation released the report for its Project LOTUS (Long-term impact of continuous use of biofuels on vessel operations) study. Launched in May 2024, it was a six-month trial to assess the impact of continuous use of a B24 blend, comprising 24 percent fatty acid methyl ester (FAME or biodiesel) with very low sulfur fuel oil (VLSFO).
The focus of the study was on engine performance and operations of the fuel oil delivery systems. According to GCMD, until now, the impacts of long-term use of biodiesel on main and generator engines, fuel storage and supply systems, and other shipboard components have not been comprehensively evaluated. Additionally, operational protocols for fuel conditioning, onboard storage, and comprehensive inspection checklists remain limited.
Project LOTUS was designed to address those gaps by implementing a structured monitoring approach to track fuel and lubricant quality at key sampling points across these systems, and inspect engine and fuel system components throughout the trial.
The report highlights that the continuous use of the fuel blend had no adverse impact on engine performance or the operation of the fuel oil delivery system. Further, the project developed a structured monitoring framework tailored for continuous biodiesel use.
“Project LOTUS grounds the conversation around the extended use of biofuels in evidence,” said Professor Lynn Loo, CEO of GCMD. “Our findings show that they can be deployed safely and reliably, providing a concrete pathway for shipping’s decarbonization.”
As part of the project, they tested 94 fuel and lubricating oil samples, along with conducting detailed engine inspections and measurements during the vessel’s dry dock overhaul. At the conclusion of the six-month study, the main engine on the NYK car carrier had operated for 2,888 hours and the auxiliary engine for 1,813 hours.
GCMD reports the engines performed comparably to when they operated in VLSFO. Key observations confirmed no excessive sludge in fuel injection valves, no scratches in fuel injection pump plungers, and no liner or piston wear beyond original equipment manufacturer (OEM) specifications. Scavenge drain and engine oil analyses also showed no excessive wear elements.
Another key concern, the impact of prolonged biodiesel storage, was tested with the report showing that the fuel quality remained within ISO 8217 specifications. They did find that the acid value of B24 blends increased 2.5-fold after six months of storage, but no microbial growth was observed in fuel samples.
OEMs also confirmed engine and hardware compatibility with long-term B24 use, with no significant impact on operational costs, provided appropriate maintenance and handling practices are followed. Further, they conducted interviews with other vessel operators using biodiesel and found similar results.
Further, the report notes that while OEMs and classification societies take an abundance-of-caution stance, the vessel operators surveyed have adopted a more pragmatic, risk-based strategy to adopting biodiesel blends by adapting existing standard operating procedures for VLSFO with recommended technical guidance where practicable. The report concludes that this suggests that when operators carry out appropriate operations in line with such guidance, biodiesel use does not present major issues.