Can I use Biodiesel in my generator?

While biodiesel is certainly appealing in some ways, in its current state of refinement it is totally unsuitable for long range cruisers, sailboats, boats with very large tanks and standby generators.

Here's the short version of why:

1. Biodiesel degrades quickly, like milk. It must be used within 90 days of manufacture, a near impossibility in marine applications and standby generators.
2. Biodiesel's strong solvent-like properties do a great job of cleaning normal accumulations of asphaltenes from tanks and fuel lines; the freshly loosened debris plugs the filters.
3. Most of the flexible hose components, gaskets, seals, diaphragms and O-rings will be gradually softened and/or dissolved by biodiesel. The problem is insidious because the engine will run extremely well until the problems begin.
4. Once the dissolved materials begin to enter the fuel system, fuel injection system failures and upper cylinder failures can occur - these materials were never designed to be burned in the combustion chamber. External leaks and filter plugging are the least of your worries. The longer term fuel system and engine component failures are likely to be much more oppressive and expensive.

Without debating the merits or challenges of biodiesel, I hope that these challenges are overcome in the not too distant future. The reality for now is that it really only works well in some highway vehicles and agriculture/ construction equipment where all the fuel is consumed in a few days.

• Engine oil and filters (oil and fuel) must be changed after the first 25 hours of operation using biodiesel due to the danger of blockage caused by loosened deposits.
• Reduce engine oil change to 30% of the interval required for operation with fossil diesel, replacing all oil and fuel filters at each oil change.
• Prior to any extended period out of operation the fuel system must be flushed by running the engine for at least 30 minutes on fossil diesel.

Other interesting information.

• Biodiesel is an extremely effective solvent so contact with painted surfaces should be avoided.
• Biodiesel will deliver 8-10% less power and therefore result in a corresponding increase in fuel consumption.
• A certain amount of fuel always finds its way into the engine oil via pistons and cylinders. Its high boiling point means that biodiesel does not evaporate but remains in the engine oil in its entirety. Under certain conditions chemical reactions may take place between biodiesel and engine oil. This can lead to engine damage.
• Biodiesel may be referred to as 'FAME' (Fatty Acid Methyl Ether.)

Clearly, after arriving at a location with fossil diesel one may choose to remove any remaining biodiesel from onboard tanks or at least flush the engine from a 5 gallon can if removal is not an option