BioDiesel

**Biodiesel: **
Produced through a process in which organically derived oils are combined with alcohol (ethanol or methanol) in the presence of a catalyst to form ethyl or methyl ester. Biodiesel can be made from soybean or Canola oils, animal fats, waste vegetable oils, or microalgae oils.

=__ 5 Reasons for Encouraging the Development of Biodiesel in the US:  __= It is obvious that biodiesel is not going to completely replace petroleum-based diesel fuel in the near future. If all of the vegetable oil and animal fat were used to produce biodiesel, we could only replace about 15% of the current demand for on-highway diesel fuel. So, why bother with biodiesel?
 * **On-highway Diesel (billion gallons**) ||
 * 1996 || 26.96 ||
 * 1997 || 28.61 ||
 * 1998 || 30.15 ||
 * 1999 || 32.06 ||
 * 2000 || 33.13 ||

There are five primary reasons for encouraging the development of biodiesel in the United States. 1. It provides a market for excess production of vegetable oils and animal fats. There is increasing demand around the world for soybean meal to provide the protein for human and animal consumption. If new markets are not found for the soybean oil, then the price will be low and farmers will have even more difficulty producing a profit. The animal by-products industry also has a problem with more supply than the current market can absorb. This is compounded by the potential for even greater restrictions on the use of animal fats in animal feeds because of concerns about the spread of [|**BSE (Bovine Spongiform Encephalopathy - Mad Cow Disease)**].

2. It decreases the country's dependence on imported petroleum. Obviously, this reason should not be overemphasized since the percentage of the country's fuel supply that can be replaced with biodiesel will be small. However, petroleum markets tend to be sensitive to small fluctuations in supply so an additional source of fuel can have a surprising impact on keeping fuel prices stable.

3. Biodiesel is renewable and contributes less to global warming than fossil fuels due to its closed carbon cycle. Because the primary feedstock for biodiesel is a biologically-based oil or fat, which can be grown season after season, biodiesel is renewable. And, since most of the carbon in the fuel was originally removed from the air by plants, there is very little net increase in carbon dioxide levels. However, some fossil carbon is contained in the methanol used to make methyl esters, and some fossil fuel is used during the production process. A life cycle study on biodiesl use in an urban bus conducted by the National Renewable Energy Laboratory [1] found that CO2 emissions were reduced by 79% for pure biodiesel compared with petroleum diesel fuel. Again, this reason should not be overemphasized because biodiesel does not have the potential to make a major impact on the total carbon dioxide production.

4. The exhaust emissions from biodiesel are lower than with regular diesel fuel. Biodiesel provides substantial reductions in carbon monoxide, unburned hydrocarbons, and particulate emissions from diesel engines. While the carbon monoxide and unburned hydrocarbons from diesels are already very low compared with gasoline engines, biodiesel reduces them further. Particulate emissions, especially the black soot portion, are greatly reduced with biodiesel. Unfortunately, most emissions tests have shown a slight increase in oxides of nitrogen (NOx) emissions with biodiesel. This increase in NOx can be eliminated with a small adjustment to the engine's injection timing while still retaining a particulate decrease.

5. Biodiesel has excellent lubricating properties. Even when added to regular diesel fuel in an amount equal to 1-2%, it can convert fuel with poor lubricating properties, such as modern ultra-low-sulfur diesel fuel, into an acceptable fuel.

//Reference: Sheehan, J., V. Camobreco, J. Duffield, M. Graboski, and H. Shapouri, Life Cycle Inventory of Biodiesel and Petroleum Diesel for Use in an Urban Bus," Report from the National Renewable Energy Laboratory for the U.S. Department of Energy's Office of Fuels Development and for the U.S. Department of Agriculture's Office of Energy, NREL/SR-580-24089, May//

=** Biodiesel Uses **=

There are many ways to use alkyl esters including as solvents and as chemical intermediates for the formation of detergents. However, the application of most interest to us is as fuel. Fuel applications can be divided into 3 categories.

Biodiesel can be used in its pure form, also known as //neat// biodiesel, or B100. This is the approach that provides the most reduction in exhaust particulates, unburned hydrocarbons, and carbon monoxide. It is also the best way to use biodiesel when its non-toxicity and biodegradability are important. Marine applications may be important for B100. Although neat biodiesel would not be expected to cause any operational problems, its solvent properties will be at their highest intensity and may cause problems with loosening of varnish deposits in fuel tanks and lines, degradation of fuel lines because some elastomers are not compatible with biodiesel (such as BUNA rubbers), and paint removal near fuel fill ports. Concrete can also be degraded if it is subjected to chronic exposure to biodiesel. These topics will be discussed later in the section on material compatibility. B100 will also have the most severe problems with cold flow properties. These problems are discussed in detail later in this course.
 * 1.** **Pure fuel (B100)**

Biodiesel will blend with petroleum-based diesel fuel in any proportion so it is common to use blends of 20 to 50% biodiesel in 80 to 50% No. 2 diesel fuel. Blends reduce the cost impact of biodiesel while retaining some of the emissions reduction. Most of the emissions reductions appear to be proportional to the percentage of biodiesel used. The cold flow and solvency problems noted with B100 are less of a concern when blends are used.
 * 2. Blends (typically 20-50%)**

Tests for lubricity have shown that biodiesel is a very effective lubricity enhancer. Even as little as 0.25% can have a measurable impact and 1-2% is enough to convert a very poor lubricity fuel into an acceptable fuel. Although these levels are too low to have any impact on the cetane number of the fuel or the emissions from the engine, the lubricity provides a significant advantage at a modest cost.
 * 3. As an additive, 1-2% (B02)**

All three of the applications described above relate to diesel engines. Biodiesel has also been considered for use in [|spark-ignited engines], but without much success. Biodiesel is being used in a variety of non-engine applications such as solvents and paint remover.
 * Other applications:**