Biodiesel: an Alternative Fuel

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Hotline, Spring 2003

by Rachel Filippini, GASP Executive Assistant

Soybeans being ground into burgers or roasted for a healthy snack, jojoba added to shampoo and make-up, and waste cooking oil discarded from fast food restaurants… what do all of these things have in common? They can also be turned into fuel, known as biodiesel.

Biodiesel is a cleaner-burning diesel replacement fuel made from natural, renewable sources such as new and used vegetable oils and animal fats. Just like petroleum diesel, biodiesel operates in internal combustion engines, with little or no modification to the engine. The vegetable oil or animal fat must first go through a process called transesterification before being used. Transesterification is the process of using either ethanol or methanol in the presence of a catalyst, such as potassium hydroxide, to chemically break the molecule of an oil or fat into an ester and glycerol.

Biodiesel can be used as a pure fuel or blended in different percentages with petroleum diesel. B20 (20% biodiesel, 80% petroleum diesel) has shown significant environmental benefits with a minimum increase in cost for consumers. Using biodiesel in a conventional diesel engine has been shown to substantially lower emissions of unburned hydrocarbons, carbon monoxide, and particulate matter. These reductions increase as the amount of biodiesel blended into diesel fuel increases. The best reductions in emissions are seen with B100 (100% biodiesel). In addition, the exhaust emissions of sulfur oxides, a major component of acid rain, are essentially eliminated with biodiesel. Biodiesel can work with new emission control technologies, such as catalysts, particulate traps, and exhaust gas recirculation, all making biodiesel even cleaner. Nitrogen oxide emissions from biodiesel can increase or decrease depending on the engine family and testing procedures. Generally NOx emissions from B100 increase on average by 10%.

The US Department of Energy and the US Department of Agriculture have concluded that biodiesel reduces net CO2 emissions by 78% compared to petroleum diesel. This is due to biodiesel’s closed carbon cycle.1 Biodiesel may even reduce CO2 levels in the atmosphere. Consider this: growing soybeans consumes nearly four times as much CO2 as the amount of CO2 produced in the exhaust from soybean oil biodiesel.2 According to a comparative life-cycle study by the US Department of Energy’s National Renewable Energy Laboratory, biodiesel requires only 0.31 units of fossil energy to make 1 unit of fuel; by contrast, it takes 1.2 units of fossil resources to produce 1 unit of petroleum diesel.

The Energy Policy Act of 1992 (EPAct) was passed by Congress to reduce our nation’s dependence on imported petroleum by requiring certain fleets to acquire alternative fuel vehicles, which are capable of operating on nonpetroleum fuels. EPAct has authorized the following as alternative fuels: methanol, ethanol, and other alcohols, blends of 85% or more of alcohol with gasoline, natural gas and liquid fuels domestically produced from natural gas, liquefied petroleum gas (propane), coal-derived liquid fuels, hydrogen and electricity and biodiesel. The Energy Policy Act was amended in 1998 to include biodiesel fuel use as a way for federal, state, and public utility fleets to meet requirements for using alternative fuels. Then in January 2001, the Biodiesel Final Rule made it possible for fleets to earn EPAct credits for use of biodiesel blends of at least 20%. This rule does not make B20 an alternative fuel, but gives one credit for every 450 gallons of pure biodiesel used in biodiesel blends.3 There has been an increase in biodiesel users, including the US Postal Service, US Department of Energy and Agriculture, some school districts, transit authorities, national parks, garbage and recycling companies and even Pennsylvania’s own Turnpike Commission.

In 1996, the Pennsylvania Turnpike Commission was the first agency in the commonwealth to use biodiesel. In Spring 2001 the Pennsylvania Turnpike Commission implemented the conversion of the entire diesel powered fleet at all three maintenance facilities which service the Philadelphia region. One hundred and four diesel-powered vehicles are assigned to this area. The three maintenance facilities use approximately 100,000 gallons of fuel annually.

Low level blends of biodiesel (20% and less) don’t seem to require any engine modifications and can provide the same payload capacity and range as diesel. Higher blends and even pure biodiesel (B100) can be used in many engines built since 1994 with little or no modifications. However, in higher blends, attention must be paid to material compatibility and warranty issues. Pure biodiesel does not do well in cold weather because of thickening; special systems are required to compensate for this. Diesel fuels blended with biodiesel are better lubricators, which reduces engine wear and tear, making the engine components last longer. Biodiesel blends have also been shown to clean fuel systems.

The biodiesel industry is still new, but growing. On average, biodiesel sells for $1.50-$2.25 per gallon wholesale (pre-tax); taxes add another $.50 per gallon. This is why most consumers still prefer B20 over B100; it’s less expensive. The US Department of Energy is working with the biodiesel industry to reduce the cost of biodiesel to less than $1 per gallon over the next five years.4 In the future, as refineries are required to make cleaner petroleum diesel fuel, the cost difference between the two will be reduced. According to the American Biofuels Association, with government incentives comparable to those provided for ethanol, biodiesel sales could reach about 2 billion gallons per year, or about 8% of highway diesel consumption.

As we look for ways to increase our oil independence, biodiesel seems to be a clear alternative. Biodiesel promotes sustainability, local farmers’ economic livelihood, and the environment.

1. National Biodiesel Board,
3. U.S. Department of Energy,
4. U.S. Department of Energy, Biodiesel Fact sheet