Marine biodiesel

An onboard trial explored biodiesel’s impact on vessel operation

Background

Annex A of ISO 8217:2017 for Marine Fuels addresses potential marine applications of bio-derived fuels and blends of bio-derived fuels, since they are renewable and can result in reduced emissions. Current land application sees regular usage of bio-blends in automotive diesel fuel for commercial, emission and regulatory requirements. Due to the lack of generalized experience with respect to storage, handling and treatment of these fuels in the marine environment, previous versions of ISO 8217 took a precautionary approach and limited the amount of these products in marine fuel.

Because of the wide use of these products in the supply infrastructure and experience in marine applications, the current version of ISO 8217 allows for increased de minimis levels in all grades. Three new distillate grades have been created allowing fatty acid methyl ester (FAME) content. De minimis allowable levels of FAME have been increased from 0.10 per cent to 0.50 per cent. Grades DFA, DFZ and DFB have been created mimicking DMA, DMZ and DMB characteristics, except allowing up to 7 percent FAME.

Trial objectives

Prior to including FAME in any of our marine products, ExxonMobil conducted onboard trials to investigate the application of bio-derived fuels. The trial was designed to ensure that vessels’ storage and handling, as well as product consumption, has no adverse effects on vessel operation.

4,000+data points were collected to monitor onboard operations.

Trial details

More than 50,000 gallons (190k litres) of B5 biodiesel (marine diesel with 5 per cent bio-components) were used. The trial utilised two different vessels, one with 16V149s diesel engines by Detroit, and the other with Caterpillar 35-12s diesel engines. The vessels were not fitted with any special equipment or systems to consume the biodiesel. Each vessel had one engine consuming B5 biodiesel, and the other two engines onboard consumed conventional diesel with no bio components.

Trial protocol was developed to specifically monitor key aspects of biodiesel usage that have been identified as potential concerns for the marine environment. These areas include long-term storage and product stability, water affinity and microbial growth, as well as onboard handling and treatment. More than 4,000 data points were collected to monitor onboard operations. A long-term storage tank was tested to monitor stability and oxidation. Filtration systems onboard were opened and inspected to monitor possible adverse conditions.

Trial data while operating with biodiesel yielded positive results. Engine operation remained consistent, with a slight reduction in stack opacity noted. Water affinity was not seen at these bio levels. Onboard water separation in filtration systems continued to operate as designed, and marine environment generate moisture could be separated from the biodiesel. Internal surfaces of fuel systems did not display any additional material deposits such as sediment, sludging or lacquering. Product in long-term storage showed no significant degradation, including oxidation, stability and microbial growth.