Testing firm warns against blending of cashew nutshell liquid with bunker fuel
Fuels testing company CTI-Maritec has published findings advising against the use of cashew nutshell liquid (CNSL) as a marine fuel or as a blending component in marine fuel due to reported operational problems.
CTI-Maritec said that, in the past few months, several ships in the Singapore and Rotterdam area reported operational problems including fuel sludging, injector failure, filter clogging, system deposits, and corrosion of turbocharger nozzle rings.
In light of the reported problems, CTI-Maritec immediately carried out extended gas chromatography mass spectrometry (GC-MS) testing for very low-sulphur fuel oil (VLSFO) samples from these said vessels.
GC-MS testing by Solid Phase Extraction (SPE) method showed the presence of high concentrations (>10000 PPM) of cardol, cardanol, anacardic acid, and other alkyl resorcinols. All mentioned compounds, which are substituted long chain phenols, indicated the fuel was blended with CNSL from undeclared source materials or production processes.
CNSL is a non-FAME biofuel, which is a naturally occurring by-product of the cashew nut industry and acts as a low-cost alternative renewable fuel. It is a substituted phenol, which is highly reactive and less stable owing to its high iodine value.
The application of CNSL is known in the production of plastic, resin, adhesives, laminates, and surface coatings. CNSL has high acid values and is therefore also highly corrosive. High potassium found in CNSL blend fuels cause serious post-combustion deposits and corrosion of turbocharger nozzle rings.
The latest version of ISO:8217 specifies the accepted BioFuels such as FAME based biofuels, hydrotreated vegetable oil (HVO), defined by the specifications of EN 14214, ASTM D6751, and EN 15940, respectively. These fuels are now established and acknowledged by original equipment manufacturers, classification societies, and flag administrations as "drop-in" fuels. There is no specification available for CNSL from any authorised body like above.
CTI-Maritec therefore recommends that shipowners should not use 100 per cent CNSL as a marine fuel or use CNSL as a blending component in marine fuel, which is contrary to the guidance by IMO on best practices for suppliers on the quality of fuel oil delivered to ships.
Furthermore, CTI-Maritec recommends not using unestablished bioproducts in marine diesel engines. Blending these substances in a marine fuel might meet specifications as per ISO:8217 tables one and two parameter limits but may not fulfil general requirements of compliance as per Clause 5 of ISO:8217.
