Warning Issued on Cashew Shell Fuel Due to Engine Room Issues

Shipowners have been cautioned against using fuel blended with cashew nutshell liquid (CNSL), a niche alternative fuel linked to significant operational problems in engine rooms.

Bunker fuel testing firm CTI-Maritec has reported that vessels refueling in Singapore and Rotterdam have experienced issues such as fuel sludging, injector failures, clogged filters, system deposits, and corrosion of turbocharger nozzle rings.

Through gas chromatography mass spectrometry testing, CTI-Maritec analyzed very low sulphur fuel oil (VLSFO) samples and discovered the presence of CNSL. The liquid, derived from undeclared source materials or production methods, had been blended into the fuel.

CNSL, a cost-effective renewable fuel, is a substituted phenol known for its high reactivity and instability due to elevated iodine values. It also has high acid levels, making it extremely corrosive. Additionally, high potassium content in CNSL blends contributes to post-combustion deposits and turbocharger corrosion.

It’s important to note that fuel containing cashew nutshell liquid is not approved as a drop-in biofuel by equipment manufacturers, classification societies, or flag administrations.