New white paper explores key considerations on biofuels

Wallem Group has published a new whitepaper to ensure ships, ships systems and crews are fully prepared to load, store and use biofuels in everyday vessel operations.

The “Marine Biofuels: Adoption, use, and best practice” report recognises the contribution that biofuels can make to maritime decarbonisation, while also offering comprehensive guidance on the precautions owners and crew need to consider before and during use.

Key observations and lessons learned

Based on experience so far in biofuel usage, Wallem shares the following observations:

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Challenge faced: FAME biodiesel’s hygroscopic nature caused microbial growth (Pseudomonas), leading to sludge and blocked pipelines, impacting tank cleaning costs and causing voyage delays.

Lessons learned: Mandatory use of biocides and tank coatings for FAME storage.
Challenge faced: A 20% biofuel blend caused injector fouling and fuel pump wear due to oxidised deposits, necessitating unplanned dry-docking for component replacements.

Lessons learned: OEMs mandate maximum blend ratios (e.g., B30) and upgraded elastomer materials. These must be adhered to.
Challenge faced: Hydrotreated Vegetable Oil’s (HVO) high cloud point led to wax crystallisation in sub-zero temperatures, blocking fuel filters, causing propulsion loss, and requiring emergency tug assistance.

Lessons learned: Cold-flow improvements and heated fuel lines are essential in cold climates.
Challenge faced: Improper FAME/High Sulphur Fuel Oil (HSFO) blending caused phase separation, clogging separators, resulting in engine shutdown and costly repairs.

Lessons learned: Pre-blending compatibility testing and segregated storage tanks are necessary.
Challenge faced: Uncertified palm-oil biofuel failed EU RED II requirements due to missing RSB certification, leading to fines and retroactive carbon levies.

Lessons learned: Only RSB/ISCC-certified biofuels are accepted in EU ports.
Challenge faced: The vessel’s Hull and Machinery claim was denied due to biofuel acidity exceeding OEM limits, resulting in substantial repair costs borne by the owner.

Lessons learned: Insurers require pre-approved biofuel specifications and OEM compatibility statements. These are mandatory before trials or operational use.

However, with a lower calorific value than fossil fuels, biofuels also present adoption challenges that require close attention from procurement, technical and vessel operating personnel, notes Abhijit Ghosh, Head of Maritime Technology and Innovation, Ship Management, Wallem Group.

The combination of a centralised digital system for real-time tracking and analysis of biofuel consumption and a skilled and well-trained crew can be transformative for enabling the future-ready maritime fleet

… said Ghosh.

Best practice tips for marine engine biofuel combustion

Check fuel lubricity, acid number, and biofuel properties based on potential impacts on fuel system components, fuel injection equipment, common rail systems, and control units.

(As per ISO 8217:2024 standards, biofuels must meet strict lubricity (<460 µm wear scar) and TAN limits (<2.5 mg KOH/g) to ensure compatibility with modern engines.)
Check the solvent effect of biofuels on fuel system deposits and coatings.

(Some makers recommend 10 μm filters for biofuels.)
Check the suitability and potential impacts of using low-viscosity biofuels.

Limit: 2–10 cSt at 40°C.
Check the impact on trunk piston engine lubricating oil from biofuel combustion.

(For B30 biodiesel blends, specialised lubricants with higher detergency and dispersancy are often prescribed.)
Check thermal management of the biofuel, including required heating (or cooling) and fuel drain arrangements.
Check the influence on exhaust emissions abatement systems, including operation, monitoring, and control.

(Monitor NOx conversion rate (%) and ammonia slip (ppm) via continuous emissions monitoring.)
Check the materials of fuel system components, especially seals exposed to biofuels.

Elastomer Swelling Limit: ≤10% volume change (e.g., MAN ES for Viton/FKM seals).
Check biofuel against blending limits provided by OEMs.