Biodiesel

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Comparison of Biodiesel to Ultra Low Sulfur Diesel

Biodiesel and ultra low sulfur diesel (15ppm) are both options to address emissions from diesel vehicles and are particularly valuable for use in existing vehicles.

Engine Modification/Equipment Requirements: Both biodiesel and ultra low sulfur diesel can be used in existing diesel vehicles, typically without modification to the engine or other vehicle components.  To achieve significant emissions reductions from ultra low sulfur diesel, additional emissions control equipment must be installed on existing diesel vehicles. The combination of the ultra low sulfur fuel and the emissions equipment results in very low emissions compared to standard diesel engines operating on low sulfur diesel. With the implementation of the new heavy-duty vehicle emissions standards in 2006, the need for additional equipment will be eliminated, as this equipment will be standard on all new vehicles.  Biodiesel can be used in virtually all existing diesel engines without the installation of additional equipment, but is compatible with this equipment and can also be used in the new, 2006 compliant engines.

Emissions Reductions: The following chart provides a general emissions reduction comparison of biodiesel and ultra low sulfur diesel (ULSD) (15ppm sulfur content). This information is not intended to represent a detailed scientific analysis. The information has been compiled from a variety of sources, including the Environmental Protection Agency, Department of Energy, the National Biodiesel Board and emissions control equipment manufacturers. Actual emissions reductions may vary from the data provided. 

* Toxics: Reports vary in their description of toxics tested. Some refer to Toxic HCs, while others refer to PAHs and NPAHs.  For simplification, data for each of these has been included under the toxics category.
** Information not available.
*** Additional information on emissions reductions from retrofit equipment can be found at: http://www.epa.gov/otaq/retrofit/retroverifiedlist.htm 

Fuel Costs: The price of these fuels is dependent on the location and quantity of fuel delivered. For delivery to a fleet, ultra low sulfur diesel in the Puget Sound region ranges from $.05 to $.15 more per gallon compared to standard petroleum diesel. The price is anticipated to move to the lower end of this range for most users in the near future. There is currently no retail sale of ultra low sulfur diesel. Fleets taking delivery of biodiesel as a B20 blend typically pay $.12 to $.20 cents more per gallon compared to standard petroleum diesel. The retail price of pure biodiesel ranges from approximately $2.50 to $3.25 per gallon. The price of biodiesel is expected to continue to decrease as additional distributors and retail sellers compete in the market and with the development of in-state production facilities.

Equipment Costs: Significant emissions reductions from the use of ultra low sulfur diesel are achieved through the use of emissions control equipment. New diesel vehicle emissions standards will require emissions control equipment on all heavy-duty diesel vehicles beginning in 2006, likely resulting in increased vehicle cost. Emissions control equipment can be installed on existing diesel vehicles using ultra low sulfur diesel, with an estimated average cost of $6,000 for particulate filters and a cost of $1,000 to $4,000 for oxidation catalysts, plus installation. The use of biodiesel generally does not require any engine modification. The use of biodiesel, even at a 20% blend, provides greater emissions reductions than the use of ultra low sulfur diesel in pre 2006 engines without emissions control equipment. Biodiesel is compatible with emissions control equipment, though real-world experience is currently limited.

Energy Policy Act: Biodiesel qualifies as an alternative fuel under the mandates of the Energy Policy Act (EPAct), thereby allowing fleets to meet EPAct mandates with existing vehicles. 

Greenhouse Gas Emissions: Lifecycle analyses show that the use of biodiesel reduces CO₂ emissions.

Carbon Offsets and Credits: Because the use of biodiesel results in reductions in CO₂, some users may be able to offset carbon emissions from other sources or may be able to sell carbon reduction credits to other entities, thereby gaining regulatory and economic incentives for their biodiesel use.

Energy Independence and Sustainability: Biodiesel is domestically produced, providing energy independence from our nation’s current reliance on imported sources of oil. Biodiesel also promotes environmental sustainability, as it is made from renewable resources, such as soybean oil and the recycling of used frying oils.

Energy Balance: Biodiesel has the best energy balance of any liquid fuel. Every unit of energy needed to produce biodiesel results in 3.24 units of fuel energy. In contrast, diesel has a negative energy balance, requiring more energy to produce than is generated by the diesel fuel.

Cold Weather Issues: The cloud point of ultra low sulfur diesel and biodiesel is higher than that of standard petroleum diesel, requiring some precautions with the use of either fuel. 

Lubricity: The use of ultra low sulfur diesel results in a loss of lubricity, which can result in high rates of fuel system component wear.  Lubricity additives can overcome this problem.  Biodiesel actually improves lubricity, even as a low percentage additive to ultra low sulfur diesel.

Safety/Spill Hazard: Biodiesel, particularly in its pure form, provides the safety benefit of a higher flash point than petroleum diesel. Biodiesel also provides the benefits of being biodegradable and non-toxic, reducing concerns related to leaking storage tanks and spills.

Compatibility: Biodiesel can be blended with ultra low sulfur diesel. As noted above, even at low percentage blends, this can have a positive impact on the lubricity of ultra low sulfur diesel. While test results are not currently available, a blend of these two fuels may result in greater emissions reductions than a blend of biodiesel with standard petroleum diesel and greater emissions reductions than ultra low sulfur diesel alone, without the use of additional emissions control equipment.

Additional Resources:

• The Puget Sound Clean Air Agency has developed the Diesel Solutions Program to bring ultra low sulfur diesel fuel in to the region and encourage the installation of emissions control equipment on existing diesel vehicles. 
• New Regional Study Confirms Air Toxics Concern The public health risks from toxic air pollutants are a significant problem for our region, according to a draft final research report released by the Puget Sound Clean Air Agency. At least 70 percent of the toxic risk is attributable to diesel exhaust.
• EPA Releases Diesel Exhaust Health Assessment The U.S. Environmental Protection Agency's  Health Assessment for Diesel Engine Exhaust states that long-term exposure to diesel exhaust is likely to cause lung cancer.