Long-term operational performance confirmed for B24 blend

Launched in 2024, a six-month trial of B24 FAME blended with VLSFO on a 25-year-old pure car and truck carrier (PCTC) confirmed main engines and gensets, which ran on B24 for 2,888 and 1,813 hours respectively, performed comparably to when they operated on VLSFO.

The trial was undertaken because, over the past decade, biodiesel trials onboard vessels have primarily focused on combustion characteristics and the extent of emissions abatement. Publicly available data on how their continuous use has impacted the integrity of onboard fuel delivery systems and engine performance remains limited.

The PCTC used for the trial, owned by NYK Line and classed by ClassNK, has a J-ENG 8UEC60LS 2-stroke propulsion engine, Daihatsu 6DK-26 generators and Mitsubishi Kakoki Kaisha SJ40F fuel oil purifiers.

The vessel operated on a short-sea route in Southeast Asia and bunkered in Singapore. For the study, 4,000 metric tonnes (MT) of B24 used cooking oil derived FAME in VLSFO was bunkered four times over the six months.

Laboratory testing, comprising 94 fuel and 91 lubricating oil samples, along with engine inspections and measurements, confirmed that the continuous use of a B24 blend did not adversely impact the vessel’s engine performance or fuel delivery system.

There was no excessive sludge in fuel injection valves, no scratches in fuel injection pump plungers, and no liner or piston wear beyond OEM specifications. Scavenge drain and engine oil analyses also showed no excessive wear elements.

While the acid value of B24 blends increased 2.5-fold after six months of storage, the fuel quality remained within ISO 8217 specifications. Density and viscosity remained stable, and water content remained consistently low at an average of 0.2% v/v. The maximum allowable limit is 0.5% v/v. No microbial growth was observed in fuel samples.

Acid number increased gradually indicating chemical changes over time, likely due to auto-oxidation. However, it remained well below the maximum allowable limit as specified in ISO 8217. This could change if the storage tank was heated or if storage was extended beyond six months. The researchers therefore recommend monitoring of fuel quality.

Biodiesel has a 10% lower calorific value than VLSO, so the use of B24 was expected to increase fuel oil consumption (FOC). Testing showed FOC increased 17% at 12 knots and 3% at 16 knots. The increase at low speeds was higher than expected, and the researchers concluded that other factors may be involved which require further investigation.

As a preventative measure when using biodiesel, engine OEMs currently recommend maintenance be conducted at a frequency at least double that of standard fuels.

GCMD trials show promise of tracers in combating marine biofuel fraud

The Global Centre for Maritime Decarbonisation (GCMD) has evaluated biofuel tracer technologies and confirmed they can be integrated into existing marine biofuel supply chain practices without disrupting operations or compromising fuel quality.

Current sustainability certification schemes for FAME and HVO lack physical, field-level verification, leaving biofuel supply chains vulnerable to adulteration, and their emissions reduction double-counted to support false subsidy claims. GCMD’s trials therefore addressed this gap by deploying tracers and assessing their capability for providing physical proof to both identify authenticity and quantify biofuel volumes.

GCMD trialled three extrinsic tracer candidates, synthetic DNA (Tracer A), element-based metalloid (Tracer B), and non-fluorescent organic (Tracer C), across six supply chain trials, deploying them at the earliest feasible upstream points and tracking them through to storage and use onboard receiving vessels.

Tracer A was detected at most sampling points in its initial trials, but detection downstream was inconsistent, particularly on receiving vessels. Tracer B was successfully detected at all sampling points and showed the highest tolerance to harsh operating conditions typical of marine fuel environments. However, discrepancies of 30-40% between expected and detected concentrations were found.

Tracer C was consistently detected at all sampling locations. At deployment concentrations below five parts-per-million (ppm), detected values closely matched expected concentrations, with discrepancies less than 5%. Its robustness, combined with cost competitiveness and detectability with commonly administered Gas Chromatography-Mass Spectrometry (GC-MS) tests, suggests that Tracer C holds significant potential as both a reliable identifier and quantifier in marine fuel supply chains, says GCMD.

Using data collected from these trials, GCMD developed an actionable comparative benchmarking framework to guide stakeholders in tracer deployment.

NYK tests viability of bio-residue

NYK is reusing a generator that had been installed on the tugboat Sakigake before its conversion into an ammonia-fueled tugboat to evaluate the safety of using biofuels.

The testing includes the use of bio-residue, a lower-grade fuel derived from standard biofuels that is produced as a byproduct during the refining process of biofuels.

Kanefumi Uematsu, manager of the Marine Group’s Marine Engineering Team, stated, “Bio-residue is expected to be more cost-effective than conventional biofuels while maintaining a similar GHG intensity (GHG emissions per unit of energy). Our immediate goal is to ensure that bio-residue can be safely and effectively used in actual operations.”

Some types of bio-residues can cool and solidify in tanks or pipelines, he says. Fuels that solidify easily also tend to produce more soot during combustion.

“Biofuels are considered organic matter and are prone to deterioration. When biofuels degrade, they can produce acids, leading to corrosion issues with components.” To address this, soot collected from the fuel and exhaust is analyzed. Key factors such as onboard storage, blending stability, equipment impact, and exhaust emissions are also being evaluated.