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VPS: Shipowners turn to ‘highly reactive’ Cashew Nut Shell Liquid (CNSL) biofuel blends for marine fuel

Competition for FAME from aviation and road transportation sectors have resulted in some shipowners resorting to adopt more readily available CNSL blends as biofuel for vessels, explains Steve Bee.

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The drive towards decarbonisation has lately brought shipowners to adopt Cashew Nut Shell Liquid (CNSL) as a biologically renewable resource for marine fuel, learned bunkering publication Manifold Times.

“One of the latest biofuels to come into the marine market is CNSL,” said Steve Bee, Group Commercial Director, VPS at the VPS Biofuels Seminar on Wednesday (15 February).

“CNSL is a bio component used instead of FAME and is a naturally occurring byproduct of the cashew nut industry. It’s a substituted phenol, a low-cost renewable substance, and chemically reactive.”

Competition for Fatty Acid Methyl Esters (FAME), a traditional component of biodiesel, from the aviation and road transportation sectors have resulted in some shipowners resorting to adopt more readily available CNSL blends as biofuels for their vessels, explained Bee.

He highlighted properties of CNSL seemed to conform with the ISO 8217:2012 standard for marine distillate and marine residual fuels, but warned CNSL-blended fuels with MGO, VLSFO or HSFO have shown mixed reactions to vessel operations.

“Some CNSL-blends have been stored and burnt without issue, whereas others have given rise to operational problems including fuel sludging, injector failure, filter clogging, system deposits, corrosion of turbocharger nozzle rings, and damage to SCR units, amongst others,” he shared.

“The thing to remember is CNSL, though not corrosive to copper or steel, is a reactive phenolic compound which can polymerise forming gums while also creating fuel deposits.”

According to Bee, CNSL is used as an effective monomer in many industrial plastic applications such as resin manufacturing, adhesives, laminates, and surface coatings production due to its ability to polymerise when heated above 200°C.

“CNSL is a long chain substituted phenol, which as a monomer is highly reactive,” he highlighted.

“The thing to be aware of for CNSL is it exhibits very high acid values usually greater than 3mg KOH/g; and considering the ISO 8217 limit is 2.5mg KOH/g, pure CNSL is highly corrosive.

“In terms of its iodine value, these are also very high at greater than 300 g I2/100g so it’s highly reactive and less stable.

“Further, potassium levels within CNSL are typically high leading to potential post-combustion deposits and corrosion of turbocharger nozzle rings.”

Bee recommended shipowners to not use 100% CNSL as a marine fuel and advised stakeholders to initiate discussions with their OEMs on the material compatibility of CNSL-based biodiesel blended products.

“Though blending 100% CNSL will reduce its high acid number, reactivity and potassium levels while increasing energy content, the operation may increase sulphur, cold-flow and sediment potential issues instead,” he pointed out.

“CNSL blends can also significantly reduce hydrocarbon, CO/CO2 and smoke emissions, although they raise NOx emissions slightly.

“Absence of sulphur in CNSL will require marine engine lubrication oils with low TBN and high detergency in order to provide efficient engine lubrication and prevent scuffing.

“Don’t try and store this material for longer than three months. And if that is unavoidable, then tests every couple of months for acid number, iodine value, plus obviously ISO 8217 parameters will have to be done.”

Moving forward, Bee was keen to introduce an Additional Protection Service for biofuels based on VPS’ experience of having tested more than 1,000 biofuels as marine fuels.

“Biofuels will certainly reduce carbon dioxide emissions from ships and certainly help towards a reduction in pollution from the global fleet,” he stated.

“But they do come with their own individual considerations in terms of transfer, storage and use. Good fuel management and understanding of the pros and cons of biofuels should mitigate the risks of using this particular material.

“My final message is please use VPS’ experienced expertise to support you, in your use of biofuels, to protect your assets, to protect the crew, and protect the environment.”

Related: VPS organises seminar on biofuel bunkers in Singapore
Related: VPS launches APS-BIO offering biofuels protection service against potential damage

 

Photo credit: Manifold Times
Published: 17 February, 2023

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Alternative Fuels

ICS report: LNG and biofuels seen as most viable marine fuels over next decade

This was followed closely by HFO combined with abatement technologies while methanol ranked in fourth place, according to ICS’s new Maritime Barometer Report.

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A new report by the International Chamber of Shipping (ICS), published on Tuesday (23 June) found that  LNG and biofuels are seen as the most viable marine fuels over the next decade.

This was followed closely by HFO (Heavy Fuel Oil) combined with abatement technologies while methanol ranked in fourth place. 

The report found that in 2025 to 2026, maritime leaders are displaying a preference for traditional fuels that have established supply mechanisms. 

The ICS Maritime Barometer Report 2025–2026 surveyed C-suite level leaders, shipowners, and operators worldwide to identify the key risk areas shaping shipping. 

Despite slight decline, LNG shared top spot with biofuels as one of three most viable future fuels over the next decade. 

LNG maintained its position as a joint leading fuel in the Barometer, with roughly 51.35% of leaders naming it as one of the most viable fuels over the next decade. 

“This is despite a marginal softening in sentiment amongst maritime leaders compared to last year’s survey, reflecting its continued role as the most immediately scalable alternative within the current fuel mix,” the report said. 

However, the report noted that this positioning is increasingly shaped not just by infrastructure maturity, but by how geopolitical instability translates into fuel-specific perceptions of security, routing exposure, and price volatility across global trade flows.

This is particularly evident in Asia-Pacific and the Middle East, where LNG’s role is reinforced through continued investment in import and bunkering infrastructure.

Singapore remains the world’s leading LNG bunkering hub, supported by expanding small-scale supply chains and vessel availability, while South Korea and China are rapidly scaling receiving and bunkering capacity to support both shipping and power demand growth.

Biofuels record one of the sharpest increases in sentiment across the future fuels landscape to match LNG at 51.35% in this year’s report.

“This could reflect a shift driven less by structural conviction and more by operational response to heightened uncertainty in global energy and trade systems,” it said. 

Their growing prominence could be closely linked to the increasing attractiveness of low-friction compliance options in a context where alternative fuels remain constrained by uneven infrastructure development, fragmented regulatory alignment, and delayed capital deployment across key regions.

Compared with LNG, which is shaped by infrastructure lock-in and geopolitical price exposure, biofuels offer immediate operational flexibility.

Japan has emerged as a key driver of marine biofuel adoption, with government-backed trials involving major shipping lines such as NYK testing biofuel blends on international routes. China has also expanded pilot programmes using biodiesel and waste-derived fuels in coastal shipping, reflecting a pragmatic approach to emissions reduction in regional trade flows.

Note: The ‘ICS Maritime Barometer Report 2025–2026’ can be viewed here

 

Photo credit: william william on Unsplash
Published: 26 June, 2026

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Biofuel

ExxonMobil completes first sea trial of bio bunker fuel blend made from FAME

Firm supplied a B30 VLSFO, made using FAME Distillation Residue, to Wallenius Wilhelmsen’s vehicle carrier “Titus” in Zeebrugge.

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ExxonMobil completes first sea trial of bio bunker fuel blend made from FAME

US oil major ExxonMobil on Tuesday (23 June) said it has successfully supplied a B30 0.50% sulphur marine residual fuel blend (B30 VLSFO), made using fatty acid methyl ester (FAME) Distillation Residue, to Wallenius Wilhelmsen. 

The bio marine fuel blend was bunkered by the vehicle carrier Titus in Zeebrugge ahead of the sea trial, marking a significant milestone in ExxonMobil’s journey towards supplying the marine industry with lower GHG emission fuels. 

The B30 VLSFO fuel meets the RMG380 residual fuel oil classification and complies with ISO 8217:2017 with the exception of the bio blend component. It shares similar drop-in properties to a B30 VLSFO made with FAME produced from used cooking oil (UCOME). 

The fuel has the potential to reduce lifecycle GHG emissions compared to conventional fuels. 

Importantly, marine fuels made with FAME Distillation Residue have a major advantage over FAME itself, as there is currently no competition for this material from other transport sectors. 

Additionally, when compared to FAME in VLSFO blends, several key properties of the FAME Distillation Residue are closer to the VLSFO component, such as density and viscosity. This is beneficial as users will see a lower reduction in viscosity than that of a FAME in VLSFO blend, which makes it comparatively easier to handle onboard ships. Further, extensive lab testing has shown good compatibility between petroleum-based VLSFOs and this B30 VLSFO made with FAME Distillation Residue. 

The sea trial was successfully completed with no operational concerns. The B30 VLSFO batch was bunkered without issue. The onboard storage and handling of B30 VLSFO did not result in any filtration or purification issues. Engine performance remained stable, as confirmed by comparing key parameters recorded in the performance and condition monitoring reports before, during and after the trial. 

“This successful sea trial highlights a practical, cost-effective pathway for customers to reduce their lifecycle greenhouse gas emissions while maintaining operational performance. By leveraging FAME Distillation Residue, ExxonMobil can offer a drop-in solution that supports compliance with evolving EU regulations and helps operators advance their lower GHG emission goals confidence,” said Gideon Simmelink, Account Manager Marine Fuels, ExxonMobil. 

“Wallenius Wilhelmsen has a long-standing collaboration with ExxonMobil. This trial supports our efforts to assess new fuel options and advance our decarbonization ambitions,” said Kari Haugen, Senior Manager Energy Sourcing, Wallenius Wilhelmsen. 

Subject to regional availability, ExxonMobil offers a range of bio marine fuel blends (Bio VLSFO, Bio ULSFO, Bio MGO and Bio HSFO), which we have supplied into the ARA (Amsterdam-Rotterdam-Antwerp) region (VLSFO and USLFO), the UK (MGO and HSFO) and Singapore (VLSFO). 

These solutions are designed to help meet the diverse needs of the shipping industry while helping support GHG emission reductions. Always consult with engine manufacturers as OEMs may limit bio blend percentages or specific bio components for certain engine designs.

 

Photo credit: ExxonMobil
Published: 25 June, 2026

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Biofuel

G2 Ocean rolls out book-and-claim service backed by biofuel voyages

Company has launched Emission Reduction Certificates, a new service enabling customers to reduce emissions associated with their transportation services through the use of marine biofuel.

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G2 Ocean rolls out book-and-claim service backed by biofuel voyages

Ship operator G2 Ocean on Wednesday (24 June) said it has launched Emission Reduction Certificates, a new service enabling customers to reduce emissions associated with their transportation services.

The service allows cargo owners and transport buyers to reduce their emissions from transportation by purchasing verified emission reductions generated from the use of biofuel in G2 Ocean’s operations.

The service is available to any company with emissions from transportation (Scope 3). It does not require cargo to be transported on specific low-emission G2 Ocean voyages.

For most companies, emissions from shipping are classified as indirect emissions (Scope 3) and sit outside their direct control. Reducing these emissions requires collaboration across the value chain.

Emission Reduction Certificates use a book-and-claim model, enabling customers to invest in emission reductions linked directly to maritime transport and to account for them in their climate reporting. The revenue will be reinvested in new biofuel voyages, helping create a cost-sharing model for biofuel and narrowing the gap between biofuel and regular fuel.

“Supply chain decarbonisation requires practical solutions. With our new service, Emission Reduction Certificates, customers can take immediate action to reduce their transport emissions while supporting the increased use of lower-emission fuels,” says Arthur English, Chief Executive Officer at G2 Ocean.

The emission reductions come from the use of certified biofuels on G2 Ocean voyages. They are verified and documented before being issued as digital certificates in a blockchain-connected registry. This registry tracks ownership and establishes a clear chain of custody for each certificate, ensuring that every certificate is unique and not double-counted or double-claimed.

“The certificates can be purchased and used by any company with emissions from transportation. The verified reductions are supported by audit documentation that enables credible climate reporting and emission accounting,” says Sigrid Bakken, ESG and Communications Director at G2 Ocean.

This ensures transparency, traceability and safeguards against double counting, providing customers with credible claims for decision-making, reporting and stakeholder communication.

 

Photo credit: G2 Ocean
Published: 25 June, 2026

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