(339a) The Current Status Of Biodiesel Application Technology

Biodiesel is a renewable fuel for diesel engines that is derived from natural oils and fats (e.g., vegetable oils, recycled cooking greases or oils and animal fats) and that specifically meets the specifications of ASTM D 6751. It is composed of monoalkyl esters of long-chain fatty acids, produced by the transesterification with alcohol of the above natural oils. Biodiesel is a DOE designated alternative fuel and is registered as a fuel and fuel additive with the Environmental Protection Agency (EPA). Biodiesel offers many benefits over conventional petroleum diesel. It burns cleaner, with net emissions reductions in particulates, hydrocarbons, and carbon monoxide (and with zero to slight increases in NOx). Biodiesel also possesses a high cetane number (averaging over 50) and improves petroleum diesel cetane performance when blended. Since it is naturally low in sulfur content, it also lowers sulfur emissions when blended with petroleum diesel. Biodiesel blending also imparts improved lubricity to petroleum diesel.

Since it is domestically produced, biodiesel shows great potential for reducing U.S. dependence on foreign energy supplies. It provides a ?closed economic loop? in that the feedstock can be grown locally, the biodiesel can be produced locally, and the fuel can be used locally. Furthermore, it is evident that very minimal to no infrastructure change is necessary to implement widespread biodiesel use. Biodiesel blends can be used in any diesel engine and can be transported and stored using existing infrastructure. Moreover, pure biodiesel is environmentally non-toxic and biodegradable. With its high energy balance of 3.2 to 1, biodiesel provides a beneficial 78% life cycle CO2 reduction.

In the US, over 80% of the feedstock for biodiesel production is soybean oil. However the biodiesel made from soybean oil is significantly less stable against oxidation than the rapeseed oil-based biodiesel produced in Europe. Oxidation of biodiesel results in increased viscosity, gum formation, increased acidity, increased peroxide value, and all of these changes can be problematic for the fuel delivery system and engine/transmission. Moreover, problems such as filter plugging, corrosion, hardening of rubber components, fusion of moving components, and engine deposits have been observed with low-quality (i.e., out-of-spec) biodiesel.

This presentation will give an overview of the properties of biodiesel, the production process, and the technical barriers facing the application technology of biodiesel in the United States. The effects of metals and antioxidants on the oxidative stability, and the formation of insolubles after low temperature treatment of soy-based biodiesel will be discussed. The formation of insolubles in biodiesel blends may have serious implications to the automotive fuel delivery system in terms of filter plugging and deposits on injectors and critical fuel pump components.