With stringent decarbonisation regulations already in force within the EU/EEA, the European authorities are now focusing on greenhouse gas  emissions from ships sailing in EU/EEA waters and on the GHG intensity of the fuels burnt on board. Once the measures of the 2023 IMO Strategy on Reduction of GHG Emissions from Ships are adopted, this focus will eventually stretch over a larger geographical area. 

The shipping industry needs to shift to low—to zero-carbon emission fuels, including various biofuels.Cashew Nutshell Liquid (CNSL) is an example of the explored options for ‘drop-in’ fuels alongside other alternative fuels. 

CNSL is a byproduct of the cashew nut and acts as a low-cost alternative renewable fuel. Its characteristics include high levels of acidity, which makes it highly corrosive and has poor combustion properties. However, it does improve lubricity and the energy content of the fuel blend. CNSL typically contains phenolic compounds, which have a high chance of polymerisation and can become unstable.

Recently, Skuld has seen several covered vessels reporting operational problems, mainly related to the fuel system, like injector failure, filter and heater clogging, fuel sludging, and deposit buildup due to fuel contamination. These issues were detected by extended Gas Chromatography Mass Spectrometry (GCMS) testing of Heavy Fuel Oil (HFO) and Very Low Sulphur Fuel Oil (VLSFO) samples from the vessels. The tests showed a high presence of phenolic compounds of cardol, cardanol and anacardic acid.

CNSL-blends can cause serious problems to the engine components, such as accelerated wear and tear of the fuel pump components, cracks in the fuel systems, and poor engine performance, resulting in loss of power.

Skuld advises its members and assureds always to perform due diligence when ordering or procuring bunkers.

• It is very important always to conduct a vetting procedure when selecting a good bunker supplier.  

• The latest version of ISO 8217:2024 should be used when testing the bunkered fuel. The latest version has Table 3 for Bio-Residual Marine Fuel specifications. 

• The sales terms of bunker fuels and the warranty regarding the fuel’s fitness should always be checked. 

• A Certificate of Quality should be requested prior to bunkering. 

• A fuel analysis should always be carried out before using the bunkered fuel. As these phenolic compounds cannot be detected in the standard ISO 8217 test, an extended advanced GCMS test from a reputable fuel laboratory is recommended.  

• It is also advised not to use untested or unestablished biofuel products for marine diesel engines.

Members may contact Skuld’s Loss Prevention department for any clarification on this advisory.