Lloyd’s Register Fuel Oil Bunkering Analysis and Advisory Service (FOBAS) on Thursday (8 May) released a bulletin regarding its testing on a number of fuels that have a high tested Ash content, above the 0.100%m/m limit for an RMG380 grade:

In recent days FOBAS has tested a number of fuels that have a high tested Ash content, above the 0.100%m/m limit for an RMG380 grade. These fuels were bunkered in the second half of April from ports in the ARA (Antwerp, Rotterdam, Amsterdam) region with tested Ash ranging from 0.102 to 0.127%m/m.

These fuels are all high sulphur residual fuels (>0.50% mass) with very similar properties and appear to be from the same source.

One common factor in all is the high Calcium which is a main contributor to the off-spec Ash in each case. Calcium ranged from 116mg/kg up to 181mg/kg. Sodium was also relatively high ranging from 50 to 86mg/kg., The fuels also had high acid numbers (TAN) ranging from 2.20 to 3.40mgKOH/g.

Often when we see high acid numbers (>2.00mgKOH/g) and high Calcium together this is due to naphthenic acids. These are present in the original crude oil and generally not considered any operational concern. Initial testing on some of these recent fuels show naphthenic acids to be present.

There are some additional points to clarify on the above:

• Firstly, in relation to Calcium, it may be noted that ISO8217 lists a 30mg/kg limit for Calcium. It is important to note the full clarification in the standard however, where the Calcium limit only applies in conjunction with the Phosphorus or Zinc limits of 15mg/kg, used as a measure of ULO (Used Lubricating Oil) presence, rather than to limit the Calcium content on its own.
• Sodium levels, although relatively high are all still below the 100mg/kg RMG380 grade limit.
• On any high acid number fuel, it should also be noted that just because naphthenic acids are present, it does not rule out any other contamination or potential issues with the fuel. Additional attention should be given to the performance of the fuel injection equipment and component conditions during the use of such fuels
• Although Calcium on its own is not a problem, at high levels where it increases the total Ash content as seen here, it can be an issue with increased Ash potentially leading to an increase in post combustion fouling and surging of turbocharger. This should not be allowed to accumulate in particular in the turbocharger, inlet grids, nozzle and blading.

So far we have not had any operation problems reported on the use of these fuels, however caution should be taken in particular to dealing with any increase in post combustion fouling as mentioned, and if further investigation into the nature of the acidic components present is required to confirm they are only naphthenic acids then detailed GCMS forensic testing could be carried out.

Photo credit: Louis Reed from Unsplash
Published: 9 May, 2025

David Browbank, Fuel Chemist at global technical and scientific consultancy Brookes Bell and scientific analyst, recently dived into the complexities of using Cashew Nutshell Liquid (CNSL) in marine fuel blends.

He noted that inconsistent engine performance and varying CNSL grades point to the need for more comprehensive testing and better data to ensure safe and efficient operations:

As industry stakeholders look for quick and available ways of embracing more sustainable bunker fuel sources, driven by an urgent need to reduce carbon emissions and comply with stringent IMO regulations, many are turning to Cashew Nut Shell Liquid (CNSL) as a biofuel blend option. 

Despite its growing popularity, ongoing trials continue to reveal that integrating CNSL into marine fuels as a blend component may pose operational challenges that could potentially disrupt vessel performance. 

However, due to its plentiful supply, green credentials, and the requirement to achieve short-term emission gains, many are overlooking the potential long-term operational risks associated with CSNL.

“Since CNSL comes from the cashew nut process, it is an easily accessible renewable resource.  Its extraction is efficient, and it has a smaller environmental footprint compared to traditional fossil fuels, making it a viable candidate for reducing carbon emissions.  Moreover, a robust cashew crop can ensure a plentiful and affordable supply for biofuel production,” said David Browbank, Fuel Chemist at Brookes Bell and a respected scientific analyst.   

Despite these benefits, the use of CNSL in marine fuel blends has not been without complications.  Early field reports indicate a host of operational issues that have raised concerns among maritime engineers and fuel chemists.  Many vessels using CNSL-enriched fuels have experienced problems such as fuel sludging, filter clogging, and deposits within the fuel system.  More alarmingly, there have been cases of corrosion affecting critical components like fuel pumps, injectors, and turbocharger nozzle rings.  These issues have led to increased maintenance requirements and unplanned operational disruptions for ship owners globally.

David noted that these issues are primarily due to CNSL still being in early development. 

“There’s limited research on using CNSL directly as a bunker fuel blend.  We’ve seen that some engines struggle with the raw blend, while one trial using a highly refined CNSL mix with a large proportion of Marine Gas Oil (MGO) produced good results.  However, performance varied greatly between engines, suggesting that differences in CNSL concentration or quality in various blends could affect outcomes.  Ship operators should be cautious given these potential issues,” he added.

He further emphasised the inherent uncertainties when working with new fuel blends.  “Every fuel possesses its own unique chemical signature, so predicting how each blend will interact within different engine systems remains challenging.  This is precisely why expertise from fuel chemists, marine engineers, and metallurgists is indispensable.  The current uncertainty around CNSL, along with other novel biofuel components, is posing significant hurdles for vessels trying to meet environmental standards.”

The existing fuel standards are further complicating the situation.  The latest edition of ISO 8217 permits the use of biofuel blends, but these are generally limited to Fatty Acid Methyl Ester (FAME) blends, which have clearly defined characteristics and performance limits.  CNSL, in its current form, falls outside these established parameters.  As a result, its adoption without rigorous and standardised testing protocols could lead to an increased number of disputes over fuel quality and performance between ship owners and fuel suppliers. 

Maritime operators are facing a dual challenge: balancing the environmental benefits of renewable fuels with the practical realities of fuel performance and engine safety.  While CNSL offers a pathway to reducing carbon emissions, the operational risks—such as increased maintenance costs and potential engine damage—need greater consideration.  The situation calls for comprehensive research and extensive field trials to establish reliable data on CNSL’s performance under various operating conditions.

David noted that Brookes Bell has seen an increase in the number of CNSL-related cases it handles.  As a result, the company’s team of fuel scientists have had to deepen their understanding of the commercial and operational risks associated with cashew nuts as a biofuel blend.

 “Our team is really putting in the effort to understand how CNSL reacts in different fuel blends.  By understanding the chemical fingerprint of CNSL and how it interacts with different fuel blends and engine configurations, we aim to build a robust data foundation that not only confirms its potential but also guides safe adoption.  This isn’t just about CNSL – it’s about creating a solid groundwork for new biofuels we might use, so we can meet environmental goals without risking engine performance.”

Looking ahead, industry stakeholders understand that a cautious and methodical approach is essential for CNSL use in bunker fuels.  The increasing availability of biofuel blends will require ship owners to invest in regular fuel testing and quality assurance measures.  Enhanced collaboration among fuel suppliers, researchers, and maritime operators will also be vital to ensuring that renewable fuels can be integrated into the global shipping fleet without compromising operational reliability.

Whilst CNSL represents a promising step toward a more sustainable maritime industry, its integration into marine fuel blends is fraught with challenges.  The initial setbacks, ranging from fuel system blockages to component corrosion, highlight the importance of rigorous testing and the development of standardised fuel quality parameters.  As the industry continues to pursue renewable alternatives, the path forward may be complex, but the lessons learned from CNSL trials will be instrumental in guiding future innovations. 

Photo credit: Brookes Bell
Published: 6 May, 2025

Bunker fuel testing and marine surveying business Maritec Pte Ltd (CTI-Maritec) on Wednesday (30 April) said its laboratory previously known as ‘CTI-MARITEC Maritime Services China Fuel Oil Laboratory’ has been now officially renamed as ‘CTI-Shanghai Center Fuel Oil Laboratory’.

The facility has also been further equipped to provide customers with a broader range of testing services, including marine Methanol Biofuel testing.

“In light of ongoing market expansion and the evolving demands of our clients, the decision to rename our laboratory represents a strategic initiative aimed at remaining at the forefront of fuel oil testing services,” stated CTI-Maritec.

“The new name embodies a fresh start and reflects our commitment to enhancing our service offerings through the implementation of industry-leading practices and advanced technology.”

New features of the CTI-Shanghai Center Fuel Oil Laboratory’ include:

Deepening of Marine Fuel Oil Testing: Building upon our established marine fuel oil testing protocols, the integration of advanced equipment and enhanced testing methodologies results in improved efficiency and precision, facilitating more effective oversight of the quality of vessel fuel oil.

Marine Methanol Biofuel Testing: In light of the increasingly rigorous global standards for decarbonization and the reduction of Greenhouse Gas (GHG) emissions within the shipping sector, marine Methanol is garnering heightened interest as a clean alternative bio-fuel. The CTI-Shanghai Center Fuel Oil Laboratory has taken proactive measures by providing testing services for marine Methanol. In accordance with ISO 6583 and GB/T42416 Methanol standards, our laboratory conducts precise assessments of purity, moisture content, impurities, and other critical parameters of marine Methanol. Our comprehensive and dependable testing services assist the maritime industry in making consistent progress towards decarbonization.

Expansion of Automotive Urea Testing Capabilities: Several new parameters for testing automotive urea have been introduced, encompassing full capacity assessments in accordance with GB 29518-2013 and ISO 22241-1 standards, as well as full capacity evaluations based on ISO 18611-1. These parameters thoroughly address the quality metrics for both automotive urea and marine urea aqueous solutions, facilitating robust and efficient management of exhaust treatment systems in automotive and marine applications.

Extensive Gasoline and Diesel Testing Parameters: A comprehensive array of tests is available for gasoline, including key metrics such as Motor Octane Number, Research Octane Number, anti-detonation index, distillation range, vapor pressure, and gel content. For diesel, testing services encompass density, cetane number, cetane index, distillation range, and oxidative stability, among others. Together, these extensive testing capabilities comply with the rigorous standards for gasoline and diesel fuel quality across various regions, ensuring the necessary safeguards to mitigate air pollution.

Photo credit: Maritec Pte Ltd
Published: 2 May 2025