Biodiesel: The New Kid On The Dock
Those of us who run diesel engines in our boats have by now heard the term biodiesel. The popular press would have us believe that biodiesel is made from old french fry oil, chicken fat and melted vaseline, but there’s more to the story than that. Here’s what boatsforboaters.com has learned about biodiesel, both from personal experience and available literature.
What is bio-diesel?
Biodiesel is the name given to a clean burning fuel produced from domestic, non-petroleum renewable resources. These sources include soybeans and rendered animal and vegetable fats. Although it contains no petroleum itself, it can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in compression-ignition (diesel) engines with no major modifications. It is biodegradable, nontoxic, and essentially free of sulfur and aromatics. Biodiesel is registered as a fuel and fuel additive with the Environmental Protection Agency (EPA) and meets clean diesel standards established by the California Air Resources Board (CARB).
Blending simply means that not only can biodiesel be used as a pure fuel but it can be blended with petroleum in any percentage. B20 (a blend of 20 percent biodiesel with 80 percent petroleum diesel) is a typical blend but you will see anywhere from B5 to B20 at fuel stations. One boatsforboaters.com staff member has a cruising trawler that routinely uses B20 from a local marina. He reports that the engine runs smoothly with significantly lower diesel "smell", and with no apparent change in fuel use per hour. We are also aware of a major national retailer that fuels its freight trucks with blended biodiesel, and a research and educational institution that makes its own biodiesel and uses it full strength in its tractors.
According to the National BioDiesel Board (www.biodiesel.org) the use of biodiesel in a conventional diesel engine results in a substantial reduction of unburned hydrocarbons, carbon monoxide, and soot compared to emissions from diesel fuel. In addition, the exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are essentially eliminated compared to diesel. Of course, burning a blended bio-diesel will not have the same environmental benefits as pure biodiesel.
If you are switching your boat to bio-diesel you should not need to make any engine nor fuel system modifications. However, biodiesel does act as a solvent and its use may release petroleum related fuel deposits that have naturally built up in fuel tanks and plumbing. These deposits will likely end up in your fuel filter, so the filter(s) should be checked frequently at first until several tanks of biodiesel have been run through. Modern fuel tanks are not affected in any way by biodiesel; however, if you for some strange reason are using copper, lead, tin, zinc or brass tanks, biodiesel should be avoided. You should also be on the lookout for any fuel seals or hoses on older engines that might be affected by the fuel, but we’ve heard of no anecdotal evidence in that regard.
In summary, biodiesel offers a number of benefits with little or no downside. It is clean burning, generates low pollution emissions, is easily blended at different ratios with petroleum diesel, is biodegradable and made from renewable resources. Minor concerns relative to possible issues with petroleum deposits and older fuel systems have not deterred boaters and marinas from increasingly using this fuel. So, do as some of us do and give it a try. It’s not french fry oil or chicken fat but your boat may smell just as good for using it.