Yanmar vessel engines compatible with biofuels

Yanmar Power Technology has confirmed its engines used on tugs, commercial vessels and workboats built at its Japanese factories are compatible with biofuels and gas-to-liquid (GTL) fuels.

These sustainable, alternative fuels can be used with the EY, NY and N series of diesel engines built at the Amagasaki factory and the engine series manufactured at the Tsukaguchi factory.

Biodiesel, hydrotreated vegetable oil (HVO) and GTL drop-in fuels should be used with these engines under conditions recommended by Yanmar to remain in warranty. All have benefits and disadvantages in terms of engine performance, emissions, and power, while some can increase NOx output, which could impact IMO Tier class emissions.

Biodiesel fuel is mainly made from vegetable oils such as soya beans, rapeseed, palm oil, and from bio-derived oil such as animal fats. It is used by mixing petroleum-based fuel oil with fatty acid methyl ester from which glycerine, catalyst and methanol have been removed by transesterification.

According to Yanmar, biofuels have a higher flash point than diesel and reduce exhaust smoke, particulate matter, carbon monoxide and carbohydrates in the exhaust gas. But biofuels density can adversely affect the engine performance and durability and could lead to oxidation, corrosion to aluminium, brass, bronze, copper and zinc, and damage seals, gaskets, hoses, adhesive agents and plastics.

They can cause deposition inside engines and reduce output by 2% and specific fuel consumption could increase by 3% when compared with diesel gas oil. Its higher pour point may cause fuel clogging at low temperatures.

Yanmar recommends using B50 biofuels and cutting the service interval in half for maintaining or replacing fuel filters, checking fuel pressure, sampling and replacing lubricant oil, checking fuel injection valves and replacing seals and rubber materials.

Before starting the engine, vessel operators need to drain the fuel service tank and when shutting down the engine for a long period, drain the biodiesel fuel fully.

HVO from animal fats oils or waste edible oils has oxygen removed and can be used by mixing it with petroleum-based fuel oil by any mixing density up to 100%. Yanmar says it can be used without any modification or special operation or handling in engines, since it is a drop-in fuel.

Its density is lower than diesel, causing a drop-in engine output of 2-3% and a rise in fuel consumption by 2-3%, but less NOx emissions, and HVO viscosity and lubricity are less than diesel.

Yanmar says HVO could cause excessive wear or a seizure in fuel pumps or fuel injectors due to deterioration of fuel lubricity and recommends refraining from using unrefined fuel to reduce possible sludging.

Its engines do not need any special preparations and operation conditions, but operators should strictly adhere to the operations manual.

GTL fuels are produced from chemical conversion and hydro-treatment of natural gas and are similar to HVO and diesel in storage and performance but produce fuel bleeding or leakage when mixed with other fuels.

Its density is lower, causing a reduced engine output of 2-4% and fuel consumption increase of 3-5% and its viscosity and lubricity are lower than diesel. Yanmar says there could be excessive wear or a seizure in fuel pumps or fuel injectors. It recommends independent storage and fuel lines to prevent fuel mixing.

Yanmar has a long-term vision to develop solutions with a minimal CO2 footprint for vessel owners and operators.