Insurer Skuld Cautions Against Risks of Cashew Nutshell Biofuels in Shipping

by Ship & Bunker News Team
Wednesday February 19, 2025

Marine insurer Skuld has warned that while cashew nutshell liquid (CNSL)-based biofuels are a low-cost alternative fuel, they have characteristics including high levels of acidity, which make them highly corrosive, as well as poor combustion properties.

CNSL does improves lubricity and the energy content of the marine fuel blend, but it contains phenolic compounds that have a high likelihood of polymerisation and can become unstable, Skuld said in an emailed statement on Tuesday.

Skuld advises its members and shipowners to exercise caution and conduct due diligence when ordering or procuring biofuel bunkers.

It states that there have been cases where vessels have reported operational problems, including injector failure, filter and heater clogging, fuel sludging, and deposits 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, Skuld said.

"The tests showed a high presence of phenolic compounds of cardol, cardanol and anacardic acid."

Skuld adds that cashew nutshell liquid biofuels can cause serious problems to a vessel's engine components, including wear and tear of fuel pump components, cracks in the fuel system, and poor engine performance.

In 2022, CNSL-blended fuels caused operational challenges, particularly in the Amsterdam-Rotterdam-Antwerp (ARA) region, VPS said.

Ship & Bunker News Team
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