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Research in Biodiesel Utilization

tour d
  Jonathon McCrady
Research Assistant
Department of Agricultural
and Biological Engineering
217-333-2969
mccrady@illinois.edu
Alan Hansen Alan Hansen
Associate Professor
Department of Agricultural
and Biological Engineering
217-333-2969
achansen@illinois.edu

With ever-rising fuel prices and an increasing dependence upon foreign oil, research into alternative fuel has become extremely important. Ethanol has quickly become a well-researched and known additive for conventional gasoline engines. For diesel engines, however, alternative fuels are just becoming more intensely researched. A potential replacement for petroleum diesel fuel that has come to the forefront in recent years is biodiesel. Biodiesel is a renewable fuel comprised of esters derived from vegetable oils. The vegetable oils can be from almost any oilbearing seed, such as soybean, corn or sunflower. The oil reacts with an alcohol such as methanol, but ethanol, another valuable product from crop production, can be used as well.

fig 1

Biodiesel fuels offer several advantages. Research has shown that the performance of biodiesel fuels in diesel engines is quite similar to using straight petroleum fuels. The total power loss from using biodiesel fuels is approximately 10-15%. Enhanced lubricity and better combustion characteristics have been show to promote quieter and smoother engine operation. Compared to diesel fuel, biodiesel has significant reductions in the emissions of carbon monoxide, unburned hydrocarbons, and particulate matter. These emissions are highly regulated and contribute to the total greenhouses gases already present in the atmosphere.

There are also several disadvantages to using biodiesel fuels. Overall, biodiesel has lower energy content than diesel fuel, causing a reduction in fuel economy. Current production costs keep biodiesel slightly more expensive than diesel fuel. The cold flow properties of biodiesel prevent it from being used in colder climates or in winter conditions. The flow characteristics of biodiesel have been shown to not work well in some diesel fuel injection systems. Though significant reductions in other emissions exist, biodiesel produces higher nitrous oxide emissions. The exact cause of this phenomenon is not exactly known. This greenhouse gas is becoming more strictly regulated by the government and more research needs to be completed to better understand how it is produced so it can be more effectively controlled.

fig 2

Current research activities are being conducted to understand the physical properties and combustion of biodiesel fuels. The physical properties of biodiesel fuels are highly dependent upon the composition of the fuel. Recently models have been developed that can predict the physical properties based solely upon the composition of the fuel. These models have had a significant impact on the ability to accurately model the combustion of the fuel. Newer combustion models are being used to look at the effects of the different properties of biodiesel and its effect upon combustion quality and emissions production. These models are based upon laboratory engines so that the combustion analysis can be calibrated exactly to what is seen in real-world application. Being able to simulate engine operation allows for a quicker analysis of different engine operating schemes that can handle the different properties of biodiesel to provide reduced emissions and high performance while offsetting the need for petroleum diesel fuel.