Fuel testing agency CTI-Maritec reported that several ships bunkering in Singapore and Rotterdam reported operational problems including fuel sludging, injector failure, filter clogging, system deposits and corrosion of turbocharger nozzle rings.
CTI-Maritec conducted gas chromatography mass spectrometry testing on samples of very low sulphur fuel oil (VLSFO) used by the ships and found that the fuel oil was adulterated with cashew nutshell liquid (CNSL) from undeclared raw materials or production processes.
CNSL is a low-cost renewable alternative fuel. It is a substituted phenol that is highly reactive and unstable due to its high iodine value. CNSL is also very corrosive due to its high acid value. The high potassium in CNSL fuel blends can cause severe post-combustion deposits and turbocharger nozzle ring corrosion.
Fuel made from cashew nuts is not considered a ready-to-use biofuel approved by equipment manufacturers, classification societies and flag state governments.