Finland-based fuel supply systems provider Auramarine on Tuesday (3 June) announced the launch of its Auramarine Water Content Analyser (AM Water Content Analyser). 

The technology measures and reports the concentration of water in methanol, helping ship operators take preventive action to minimise associated risks and costs when using the fuel. 

The analyser comes in response to growing uptake of methanol as a marine fuel to meet shipping’s decarbonisation targets. Water as a natural contaminant of methanol may be present in the bunkered methanol either by accident or intentionally. Water in fuel decreases the calorific heating value which increases the bunkering costs. In addition, if the water content is too high, operators may have to unload the fuel, leading to delays and additional costs.  

As an example, when a Ro-Ro vessel consumes 27 000 metric tonnes (mt) of green methanol in one year and with an average price per ton of green methanol at EUR 1,196 (USD 1,361), the operator of the vessel may avoid losses of up to EUR 1,614,600 for 5% concentration of water as contaminant. 

The AM Water Content Analyser is an inline measurement device that can be installed directly to the methanol process piping, for example to the main bunker line with the flanged housing. The technology uses a sensor to analyse the concentration of water in the methanol.

John Bergman, CEO of Auramarine, said: “Methanol uptake is increasing across the industry due to its promising Greenhouse Gas (GHG) emissions reduction credentials. At Auramarine, we’ve led the way in developing solutions that support the use of alternative fuels-starting with the industry’s first Methanol Fuel Supply Units in 2022. 

“Now, with the launch of our AM Water Content Analyser, we’re giving ship owners and operators the tools they need to take the next step in their energy transition and bunker methanol with greater confidence, and importantly, at a lower cost.”

Photo credit: Auramarine
Published: 4 June, 2025

Steve Bee, Group Marketing and Strategic Projects Director of marine fuels testing company VPS, on Thursday (29 May) explored if the greater demand for marine gas oils/distillates would lead to poorer fuel quality following the recent implementation of the new Mediterranean ECA, which is already witnessing an increasing demand for marine distillates to satisfy the 0.10% Sulphur limit. 

He also discussed the fuel management concerns and challenges associated with such marine fuels:

Introduction to Distillate Fuels

With the recent implementation on 1st May 2025, of a new Emission Control Area (ECA) in the Mediterranean Sea, the question arises, will we see an increase in demand for marine gas oils/distillates? If so, will a higher demand result in a lower quality product? This article looks to address current marine distillate quality and the test parameters which can be employed to assist in determining fuel quality and the relevant fuel management considerations, required to mitigate any associated risks through the following:

1. Density
2. Viscosity
3. Flash Point
4. Cold-Flow Properties
5. Lubricity
6. FAME
7. Microbial Activity
8. Incompatibility

For decades global shipping has thought of distillate fuels, as problem-free fuels. Yet whilst High Sulphur Residual Fuels and Very Low Sulphur Fuels, offer certain fuel management challenges, marine distillate fuels, are not exempt, they simply have different considerations and challenges.

Within the ISO8217:2024 marine fuel standard, there are four grades of fossil marine distillates, DMA, DMB, DMX, DMZ, plus three Fatty Acid Methyl Esters (FAME) containing distillates, DFA, DFB and DFZ, to support decarbonization compliance.

Today, DMA is the most commonly used marine distillate. Suitable for most marine engines, DMA is known for its cleaner combustion, consistent performance, and ability to reduce emissions when compared to heavier, residual marine fuels. This type of fuel is also commonly referred to as, Low-Sulphur Marine Gas Oil (LSMGO).

• DMA: This is the LSMGO highlighted above. As per its classification, it’s a standard marine distillate suitable for various marine engines.
• DMB: The heaviest fuel among the distillates and is typically used in medium-speed marine engines.
• DMX: Often referred to as a special light distillate, DMX is used primarily for emergency engines and equipment, plus some high-speed engines that require fuels with lower viscosity and density.
• DMZ: This is a clean distillate intended for use with more sensitive engines.

Ultra Low Sulphur Fuel Oil (ULSFO) is another similar fuel type. Marine fuels like DMA are often integrated with specific additive blends, these are designed to address and counter challenges typical of marine environments, for instance, microbial growth in storage tanks. DMA’s cetane number, which indicates the ignition quality of the fuel, usually surpasses 45, whilst ULSFO’s cetane number floats between 40 to 45. While there are premium diesel variants with a higher cetane number, the main objective of ULSFOs is to lower sulphur emissions.

The higher cost of DMA is another differentiating factor and can be swayed by marine-specific rules, the demand it witnesses in ports, and the overarching dynamics of the global marine fuel market. For ULSFO, its pricing hinges mainly on elements like crude oil prices, the capacity of refineries, transportation overheads, and the demand from the road transportation sector.

Marine Distillates (MGO) and ULSFOs account for 14.2% and 1.2% respectively, of all fuel samples sent to VPs for testing:

Whilst distillate deliveries remained stable in Q1-2025 at around 800,000mt, ULSFO deliveries have risen 15% quarter-overquarter.

Fuel Management Concerns relating to Marine Distillates

Minimising Financial Risks: Density Short-lifting – Fuel is delivered by volume but paid for by weight. Overstated density stated in a Bunker Delivery Note (BDN) results in operators paying for fuel that was not actually supplied. VPS data and vast experience indicates that short lifting of distillates significantly exceeds that of HSFO and VLSFO. This fact, together with the premium price of distillates can be a substantial drain on the operating budget of a company.

Currently 39% of MGO samples tested by VPS, fall below 850Kg/m3, where the ISO8217:2024 specification limit is 890Kg/m3.

The BDN values are predominantly higher, indicating such overstatements, result in lost fuel for the vessel.

Even without heating the fuel, a warm engine room can easily heat the fuel to e.g. 50°C. A fuel bunkered as 2cSt at 40°C, will have a viscosity of 1.7cSt at 50°C, below the required minimum 2cSt that is recommended by major engine, boiler and pump manufacturers.

Currently 99.1% of all MGO samples tested by VPS in Q1-2025, have a viscosity >2.0 CSt and less than 6.00 CSt.

Ensuring Compliance with Statutory Regulations: Low Flash Point – Flash point is the temperature at which the vapours of a fuel ignite when a test flame is applied. It is considered to be a useful indicator of the fire hazard associated with the storage of marine fuels. The Safety of Life at Sea (SOLAS) convention and ship classification society rules, require all fuels to have a flash point of more than 60°C, with the exception of Emergency Equipment (eg lifeboat engines). Yet, the Flash Point of marine distillates is an on-going issue. In 2024, the Flash Point cases relating to MGO fuels, accounted for 22% of the Bunker Alerts issued by VPS.

Poor Cold-Flow Properties: Poor cold flow properties, indicated through pour point (PP), cold filter plugging point (CFPP) and cloud point (CP), can lead paraffinic wax precipitation from the fuel. This wax can then lead to clogged filters and pipe lines and in the worst case, complete solidification of the fuels in vessel tanks if not heated sufficiently.

In Q1-2025 the average Pour Point of MGO dropped to -7°C:

Insufficient Fuel Lubricity: Marine engine fuel pumps are self-lubricated. If the lubricity of the distillate is poor, high wear may be caused usually within a short period of time. The risk of encountering poor lubricity is higher when sulphur is below 0.05% (500ppm). Therefore, in such cases testing the fuel for its lubricity level is a key requirement. This is undertaken via laboratory test method ISO12156-1, with a specification limit of 526µm Corrected Wear Scar Diameter.

Many people believe it is sulphur which actually provides the distillate with its natural lubricity. This is incorrect. The process to remove sulphur from fuel is termed, “hydrodesulphurization” and it is this process to remove sulphur which also removes polyaromatics present, which do provide the natural lubricity to fuels.

Fatty Acid Methyl Esters (FAME): It now seems ironic that prior to ISO8217:2010, FAME was seen as a contaminant if found within marine fuels. Then the 2010 revision, allowed “de-minimus” levels of FAME to be present in marine fuels. The ISO8217:2017 went a step further by including three new distillate grades, DFA, DFB and DFZ, with a FAME limit of 7% in each. Now the ISO8217:2024 allows up to 100% FAME in relation to marine biofuel blends.

Although FAME has good ignition, combustion and lubricity properties, as well as providing a reduction in GHG emissions, it can reduce oxidation stability and increase the risk of microbial growth. The risks increase if the fuel is to be stored for a prolonged period of time, e.g. more than 3 months.

Microbial Contamination: Bacteria, yeast and fungi can live and thrive in distillate fuel tanks in the presence of water and elevated temperatures. Such conditions provide an ideal environment for microbial growth. Such microbes, if allowed to grow can lead to operational issues such as clogged filters/nozzles and corrosion in fuel tanks and pipework. This situation can be further complicated by the presence of Fatty Acid Methyl Esters (FAME), which can provide a further source of nutrients for bugs to feed upon. To monitor this microbial activity it is recommended to carryout BYF-testing. Good onboard house-keeping, ensuring a water-free environment will reduce the risks of bug-growth. However, should the situation deteriorate, then biocides can be used to kill the microbes.

Incompatibility Issues: Loss of propulsion and/or fuel incompatibility during fuel change-over from HSFO or VLSFO to a distillate fuel when entering an emission control area (ECA) is another problem that ship operators should be aware of. Changing between residual-based fuels and distillate fuels can inevitably result in mixing in the fuel system. The result may be incompatible mixtures and in the worst case, a loss of propulsion.

Note: The full article by VPS can be read here. 

Photo credit: VPS
Published: 30 May, 2025

Maritime protection and indemnity (P&I) club Gard recently published an insight on Cashew Nut Shell Liquid (CNSL) and several cases it has handled involving the detection of phenolic compounds originating from CNSL in conventional fuels, which has resulted in operational problems or machinery damage for vessels.

Capt. Rahul Choudhuri of VPS assisted with this article:

Growing demand for low to zero carbon fuels across transport sectors to meet environmental regulations has increased interest in alternative sources. Fatty Acid Methyl Esters (FAME) are popular for biofuels, but high demand across various transport sectors exceeds supply. Cashew Nut Shell Liquid (CNSL), a byproduct of the cashew industry, is considered an alternative source of biofuels. 

What is CNSL?

Cashew Nut Shell Liquid, a cost-effective renewable fuel, differs from FAME biofuels. As a substituted phenol, its high reactivity and lower stability are attributed to its elevated iodine value. Beyond its fuel potential, CNSL is already used in the production of plastics, resins, adhesives, laminates, and surface coatings. Its high acid value (> 3mgKOH/g) also makes it significantly corrosive. CNSL’s key phenolic compounds that tend to polymerize, forming gums and fuel deposits include: 

• Anacardic Acid is a major contributor to CNSL’s high acidity. Thermal decarboxylation converts this to cardanol, reducing acidity and enhancing stability.
• Cardanol, also known as Ginkgol, is a stable phenolic compound derived from anacardic acid with improved combustion and lubricity properties.
• Cardol, also referred to as Olivetol, is a dihydroxybenzene derivative with surfactant-like behaviour.

Cases of CNSL causing operational problems

Cashew Nut Shell Liquid, despite its benefits of increased lubricity and energy content, poses challenges due to high acidity, poor combustion, and corrosiveness. Widespread contamination of conventional fuels with CNSL was reported in the ARA region in 2022, leading to operational problems such as fuel sludging, fuel injector failure, engine part corrosion, filter clogging, fuel system deposits, turbocharger nozzle ring corrosion, fuel pump plunger and barrel wear, and damage to Selective Catalytic Reactor (SCR) units. Since these incidents, Gard has handled several cases involving the detection of phenolic compounds originating from CNSL in varying concentrations.

Case study 1

A vessel bunkered HSFO in Southeast Asia. Despite passing initial ISO 8217, Table 2 testing and preliminary GCMS screening, the fuel soon caused main engine exhaust temperature alarms, followed by leaking injectors and stuck fuel valves. The vessel required an 800nm tow to safety. Subsequent GCMS revealed over 10,000 ppm of Cardonol. Costs incurred exceeded USD 800,000.

Case study 2

A vessel experienced significant operational issues shortly after using ULSFO that initially passed ISO 8217, Table 2 testing. Fuel was stemmed at a port in Northern Europe. Problems included high main engine exhaust temperatures, auxiliary engine failure and fuel leaks, fouled nozzles, and damaged high-pressure fuel pipes, necessitating replacement of all fuel pumps and valves. GCMS analysis revealed high levels of Cardanol (> 30,000 ppm), Cardol (> 5,000 ppm), and Anacardic Acid (> 1,000 ppm) totalling 1.24% by mass of the fuel composition. The cost of repairs exceeded USD 400,000.

We are aware of several vessels having been impacted by the same bunker delivery.

It is worth noting that there have been instances where CNSL-blended conventional fuels have been stored and combusted without any operational issues being reported.

Testing of CNSL as biofuel – VPS’s experience

VPS, in their recently published article ‘Cashew Nut Shell Liquid – Biofuel Saviour or Concerning Contaminant?’ shared the results of their testing of CNSL products, blended with marine gas oil (MGO), very low sulphur fuel oils (VLSFO) and high sulphur fuel oils (HSFO). Fuel Combustion Analysis (FCA) revealed a spectrum of outcomes for estimated cetane number, ignition delay, and rate of heat release (ROHR), with CNSL blends showing a performance gradient: the HSFO blend performed particularly poorly, the VLSFO blend showed improvement, and the MGO blend yielded the most favourable results.

Whether the blends were 80/20, 70/30 or 50/50 Fossil/CNSL, the blends using HSFO consistently gave the poorest FCA results. This may be due to a negative interaction between the asphaltenic content of the HSFO and the acidic nature of the CNSL. Each of the CNSL blends gave poorer FCA results when compared with the 100% fossil fuels, HSFO, VLSFO, MGO and 100% FAME.

They have also shared a B100 case study, where the fuel was assumed to be 100% FAME, but the analysis revealed that it was 40% FAME, 10% FAME Bottoms and 50% CNSL. Technically, the fuel was still B100, but with the Biomass comprising of different components. This emphasizes the importance of due diligence regarding fuel procurement for charterers and owners.

CNSL and ISO 8217

One of the experts Gard consulted reported that “CNSL is not a permissible component in bunker fuels, on the basis that same is not a hydrocarbon derived from petroleum refining, nor is it derived from an alternative permissible hydrocarbon source and thus falls foul of Clause 5 of ISO 8217.” VPS comments along the same lines in their alert “For the purposes of ISO 8217:2024 and all preceding versions, CNSL is not recognized as a standard fuel component. Accordingly, its presence in a marine fuel may be considered a contaminant and potentially classified as off-specification when assessed against the ISO 8217 standard”.

It’s important to note that Annex B of ISO 8217:2024 acknowledges that various chemical species or materials (though not exhaustively listed) can cause operational issues. Consequently, fuel oil purchasers might need to conduct advanced testing to identify substances that could render the fuel unsuitable for the engines. Moreover, although ISO 8217:2024 addresses biofuels, its scope does not extend to all forms of biomass

Note: The full article by Gard including key recommendations can be found here. 

Related: VPS on Cashew Nut Shell Liquid: Biofuel saviour or concerning contaminant?

Photo credit: Shaah Shahidh on Unsplash and Gard
Published: 29 May, 2025