Most diesel vehicles can also run on biodiesel blends without engine modification. Biodiesel is made from vegetable oil through a refining process called transesterification. Alcohol (e.g. methanol or ethanol) is used in the presence of a catalyst, such as sodium hydroxide or potassium hydroxide, to break the oil into methyl or ethyl esters of the oil, with glycerol as a derivative. The methyl ester of vegetable oil, or biodiesel, is similar to diesel fuel. It can be used alone or mixed with petroleum-based diesel. Biodiesel in its pure form is known as “neat biodiesel” or B100. The most common blends are B5 (5% percent biodiesel and 95% conventional diesel) and B20 (20% biodiesel and 80% conventional diesel).
Biodiesel more than tripled from 2010 to 2011.
Biodiesel has many characteristics that differentiate it as superior to petroleum-based diesel. To begin with, it runs in any diesel engine, thus, no engine modifications are needed prior to using the fuel. A second characteristic of biodiesel is that it can be stored anywhere that petroleum diesel can be stored. In addition, biodiesel is environmentally friendly because it does not give off any toxic emissions and foul odors.
Biodiesel has higher lubrication than petroleum-based diesel, thus it extends the life of an engine. Moreover, biodiesel is non-toxic, biodegradable, and safer to handle than petroleum-based diesel. Transporting biodiesel is easy because its flash point is 300° F, while the flashpoint of petroleum-based diesel is 125° F.
Biodiesel-powered engines deliver similar torque, horsepower, and miles-per-gallon than petroleum-based diesel. However, biodiesel has slightly lower energy content than conventional diesel. This means Biodiesel can provide better engine performance and lubrication, with a small decrease in fuel economy between 2-8%.
All of the benefits of biodiesel lend the product well to centrally (private onsite) fueled fleets such as transit buses and airport shuttles, as well as State and Federal government fleets.
One criticism of biodiesel is that biodiesel vehicles can have problems starting at very cold temperatures. However, this is more of an issue for higher percentage blends such as B100.
Another issue with biodiesel is availability. As of December 2014, there were only 296 public fueling stations that served biodiesel. This is not a large amount considering there is an estimated 160,000 gasoline serving stations in the United States. The distribution of fueling stations that supply biodiesel is far from uniform throughout the United States. In fact, 23 states in the U.S. have 5 or fewer fueling stations that serve biodiesel in their entire state.
Additionally, many consumers have concerns with the price of biodiesel. In April of 2013 the national average price of a conventional diesel equivalent gallon of B20 was $0.20 more expensive than conventional diesel. Blends with higher biodiesel content are even more expensive. B100 posted a national average price of $4.72 per conventional diesel equivalent gallon, which is $0.73 more expensive than conventional diesel.
The final concern with using biodiesel is that it can cause some minor maintenance problems if not properly monitored. When used for the first time, biodiesel can release deposits accumulated on tank walls and pipes from previous diesel fuel, initially causing filter clogs. Also, biodiesel can degrade rubber fuel system components, such as hoses and pump seals. This is especially true with higher-percentage blends and older vehicles, as many new vehicles have biodiesel-compatible components.
Fleet managers that want more information on the availability and costs of biodiesel fuel on a more local level should visit the U.S. Department of Energy’s Alternative Fuels Data Center. There fleet managers can find the DOE Alternative Fueling Station Locator and the Clean Cities Alternative Fuel Price Report.,
Additionally, the Alternative Fuels Data Center allows fleet managers to view their State’s incentives and laws related to alternative fuel and advanced vehicle use.