MARITEC: Cashew Nut Shell Liquid Biofuel Blended in Marine Fuel

Image Credit: CTI-Maritec

In the recent-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 swiftly 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 Cashew Nutshell Liquid (CNSL) from undeclared source materials or production processes.

CNSL is a non-FAME BioFuel, which is a naturally occurring byproduct of the cashew nut industry and acts as a low-cost alternative renewable fuel. It's 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 highly corrosive as well. 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 equipment manufacturers (OEM), Classification Societies (Class) and flag Administrations as 'drop-in' fuels. There is no specification available for CNSL from any authorised body like above.

CTI-Maritec Recommendations

CTI-Maritec recommends that shipowners should not use 100% 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.

MEPC.1 /Circ. 875/Add.1 section '5' – where it states that:

5.3 Blend components should be tried and tested so that their typical properties and suitability for bunker production and how they combine with other components is well understood...... and

5.4 Where there are any uncertainties as to the nature and quality of blend component, any issue should be identified and resolved before its use in the production of bunkers.

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 1 and 2 parameter limits but may not fulfil general requirements of compliance as per Clause 5 of ISO:8217.

CTI-Maritec can assist you with further information on the quality of bunkers tested in different regions. For further information or assistance please do not hesitate to Contact us.