Warning: Marine Engines May Also Be “Allergic” to Cashew Nutshell Biofuel

Among the alternative fuel blends being tested is liquid from cashew nutshells

Published Nov 22, 2024 2:11 PM by The Maritime Executive

 

Fuel suppliers and shipping companies continue to look at a wide range of non-FAME biofuels, but a leading testing firm is warning against Cashew Nutshell Liquid biofuel. Singapore-based CTI-Maritec which provides marine environmental services and fuel testing solutions issued the warning after finding high concentrations of detrimental compounds in fuels from undeclared source materials or production processes it sampled.

The alert says that ships fueling in Singapore and Rotterdam have reported a range of operational issues that led it to launch the tests on VLSFO (Very Low Sulfur Fuel Oil) samples from the vessels that had bunkered in those ports. They received reports of operational issues including fuel sludging, injector failure, filter clogging, system deposits, and corrosion of turbocharger nozzle rings.

CTI-Maritec reports it carried out extensive Gas Chromatography Mass Spectrometry (GC-MS) testing on fuel samples from these vessels. It found “the presence of high concentrations” of compounds indicating the fuel was blended with Cashew Nutshell Liquid (CNSL) from undeclared source materials or production processes.

“CTI-Maritec recommends that shipowners should not use 100 percent CNSL as a marine fuel or use CNSL as a blending component in marine fuel,” it writes in a Bunker Flash report issued on November 21. They note this “is contrary to the guidance by IMO on best practices for suppliers on the quality of fuel oil delivered to ships.”

The IMO specifies the accepted BioFuels such as FAME-based biofuels, Hydrotreated Vegetable Oil (HVO), and those fuels are now established and acknowledged by equipment manufacturers, class societies, and flag administrations as “drop-in” fuels. CTI-Maritec says however that there is no specification available for CNSL from any authorized body similar to those for the other fuels.

CNSL they explain 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 is a substituted phenol, which is highly reactive and less stable says CTI-Maritec 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,” according to the alert. 

They are recommending that ships not use unestablished bioproducts in marine diesel engines. They also recommend that blend compounds should be tried and tested to create an understanding of their typical properties and suitability for bunker products. How they combine with other components also needs to be well understood.