VPS has seen very few technical issues with B100. Image Credit: VPS

The 2026 Middle East conflict, including the closure of the Strait of Hormuz, through which 25% of the world’s oil & 20% of LNG flows, has triggered one of the largest global energy supply disruptions in modern history. This narrow waterway is the world’s most critical energy chokepoint, with over 80% of its oil and natural gas shipments bound for Asia.

The closure of the Strait has caused supply shortages and transport paralysis with tanker traffic nearly halted. Although the Middle East conflict situation remains fluid, if this continues to worsen, then commentators have suggested that crude oil could reach record levels.

Marine Distillates are particularly exposed, with roughly 1.15 million b/d of middle distillates being impacted by the Hormuz disruption, coupled with further price drivers such as insurance premiums making distillate supply a premium.

With distillates now at historically high levels, this has given rise to attractively priced alternative Marine Fuel sources, which are not as directly affected by Middle East crude disruptions. As Biodiesel pricing is driven in part by agricultural feedstocks, the pricing gap between B100 FAME and distillates has reduced. Thus, even if B100’s nominal price per tonne remains slightly higher than distillate, the effective cost per voyage is now materially lower or near-parity. The added environmental and legislative benefits of CO2 reduction by using B100 also leads to reduced carbon taxation due to emissions pooling under FuelEU maritime regulation.

Effectively Shipowners now see a smaller economic penalty – and in some cases a net benefit for switching to B100.

Recommended Approach for Introducing B100 FAME
VPS is seeing an increase in B100 FAME usage, although fossil fuels remain the dominant marine fuels. The use of B100 has however increased in response to the aforementioned dynamics. As the standard blend configuration, we see Bio-blends in the form of B30 being used with 70% fossil fuels, such as distillate, very low sulphur fuel oil (VLSFO) and heavy fuel oil (HSFO). These fuel blends present limited risk in terms of operational use and handling. However, Biofuels including B100, require specific fuel management considerations, which VPS has highlighted in past articles available at: Articles | VPS.

These challenges include:

• Lower energy value compared to fossil fuels.
• Susceptibility to Oxidation, making prolonged storage unsuitable and future condition uncertain.
• Oxidation can also result in increased Acid Number which increases the risk of corrosion within the fuel system, including components such as fuel pumps and injectors, in addition to potential storage tank corrosion.
• B100 FAME, has a natural hygroscopic tendency which can increase water absorption. This, in turn provides a suitable breeding ground for Microbial growth.
• A final point of consideration is the  behaviour of B100 FAME in fuel/lubricant interaction. While distillate fuels generally have a lower viscosity than FAME, FAME is less volatile due to its heavier molecular structure and higher boiling range (typically around 272°C compared to approximately 170°C for distillates). As a result where fuel ingress occurs due to leakage or incomplete combustion, B100 is more likely to remain in the lubricating oil rather than evaporate. This can lead to dilution of the lubricating oil, particularly in 4-stroke engines, resulting in a reduction in oil viscosity and potential operational problems.
• That said, B100 (FAME) is already in use by many clients, and we have seen very few technical issues. This indicates that with appropriate fuel management and handling practices, B100 can be successfully used as a drop-in fuel.

To support successful implementation and operation, VPS recommends the following:

Ideally, B100 should be introduced after tanks have been drained and flushed to minimise the presence of water that could promote, fuel instability and microbial activity. Where possible thorough tank cleaning is recommended, as there is a likelihood that tanks may contain unpumpable residues from previous fossil fuel bunkers. These residues can become mobilised due to the relatively high solvency properties of FAME, lifting tank-bottom deposits when first introduced and potentially overloading purifiers during the initial stages.

Where possible, VPS recommends compatibility (spot) analysis prior to use. Onboard blending is not recommended. However, if operationally unavoidable, B100 should be bunkered and stored in a separate tank, blended in small portions, with performance and fuel quality being evaluated before progressing to higher ratios.

Verify compatibility of the fuel system components, including seals, gaskets, hoses & coatings. Pay particular attention to elastomers and painted surfaces. Confirm suitability with the OEM for main and auxiliary engines. Ensure any required changes are reflected in the Ship Technical File (SEEMP).

When B100 must be bunkered directly into tanks containing existing MGO, the following guidance should be followed:

Operational Guidance for Changeover from MGO to B100 (100% FAME)

• Monitor engine performance: B100 (FAME) has a lower calorific value than MGO, so adjustments will be required to maintain power output. This can be noticed through elevated exhaust gas temperatures, requiring the fuel rack to be adjusted.
• Minimise water in fuel tanks: Drain tanks regularly, especially considering condensation from weather variations. Water promotes microbial growth.
• If fuel is not consumed within 3-4 months: take a representative tank sample for a quality assessment including Oxidation Stability, Iodine Value, Total Acid Number, Water Content, Cloud Point and Bacteria, Yeast and Fungi.
• Carryout the VPS recommended APS-FAME test suite, as it covers the key analyses required to assess FAME quality in line with EN14214, which is referenced under ISO8217:2024. A summary of the APS key test parameters is discussed later in this paper.
• Monitor for fuel degradation. As a bio derived product, B100 degrades faster than MGO which can oxidise quickly resulting in increasing Acid Number & Iodine value over time which is a common indicator. Where possible, check gaskets and O rings for signs of wear.
• Continuous operation on B100 may increase the likelihood of fuel dilution in the used engine oil, due to fuel ingress that remains entrained in the lubricating oil, particularly in four-stroke engines. This may result in reduction in engine oil viscosity and premature degradation of the oil, leading to reduced running hours between oil changes.
• Avoid excessive heating of fuel. Ensure fuel is suitable for ambient conditions (cold flow considerations).
• Operate separators and filters as per normal procedures. During initial use, increase monitoring of filter condition and differential pressure and separator performance.
• VPS Support through Additional Protection Service - APS-FAME

VPS additional protection service was established to provide greater understanding and insight of marine biofuel quality. Whilst the introduction of ISO8217:2024 now caters for Biofuel & Bio-blends, it is still not an all-encompassing test slate, as it places the onus on suppliers to ensure that the FAME component used for blending, or supplied as B100, complies with EN14214 or ASTM D6751. APS-FAME is therefore recommended to provide a more comprehensive assessment of fuel quality.

APS-FAME – Key Analytical Parameters Overview for B100/FAME

APS-FAME provides deeper insight beyond the ISO8217:2024 specification with respect to the quality, stability, and suitability of FAME-based marine biofuels through the following parameters:

• Corrosion @ 50°C (Steel)
• Assesses the corrosive potential of the fuel system on metallic components such as fuel pumps & fuel injectors at elevated temperatures. This helps to spot early signs of corrosivity
• Iodine Value
• Indicates the level of unsaturation (double bonds) in fatty acid chains.  A higher iodine value reflects greater unsaturation, which can reduce fuel stability and affect storage behaviour.
• Oxidation Stability
• FAME can break down overtime; this test evaluates how resistant the fuel is to degradation during onboard storage.
• Net Heat of Combustion
• For blends greater 10% FAME, the D240 method provides the only means to accurately determine the fuel’s energy content.
• Total Contamination (Particulates)
• Measures particulate levels that may lead to:
  • Filter plugging
  • Injector wear
  • System fouling
• Bacteria, Yeast, and Fungi
• A crucial parameter for FAME, due to its affinity to water, which creates favourable conditions for microbial growth.

The ongoing Middle East conflict is giving rise to serious concerns for many shipowner-operators. The significant volatility in Marine Gas Oil and Distillate pricing, as well as a potential impact on product availability, are factors driving vessel operators to seek alternative solutions.

In this environment, the commercial case for B100/FAME is expected to strengthen. Supported by a narrowing fuel price differential, plus a positive contribution towards both emerging and existing regulatory requirements, this drop-in fuel is gaining momentum as a viable marine fuel option.

While the use of B100/FAME requires more cautious fuel handling and operational considerations in order to mitigate operational risks, customers can rely upon VPS  to provide insightful support throughout this transition. Our market-leading experience and expertise in marine fuel testing provides detailed fuel quality analysis, supported by sound scientific and marine engineering advice. All of this will help our customers make more informed decisions and operate with more confidence.

For further information on B100/FAME fuel management, please contact your local VPS Account Manager, or marketing@vpsveritas.com