Reducing air pollution with biodiesel

Biodiesel can result in significant reductions in a number of air pollutants. In general, reductions are greater as more biodiesel is used, depending on the type of biodiesel (soybean, rapeseed or animal fats) and on the conventional diesel used in the blend. Emission impacts of biodiesel do not appear to vary by engine model year.

• Particulate matter dropped by almost half when using B100 (100% biodiesel), and by 12 percent when using B20 (20% biodiesel).
• Global warming impact from CO₂ dropped by almost 80 percent using B100.
• Hydrocarbons were reduced by nearly 70 percent using B100 and 21 percent using B20. Hydrocarbons include many different individual toxic compounds.
• Carbon monoxide decreased 48 percent with B100, 12 percent using B20.

Biodiesel - Diesel Emissions Comparison (EPA Data)

EPA research shows that biodiesel reduces most emissions from unmodified diesel engines; reduction depends on the blend and type (source) of biodiesel. Pure biodiesel offers the greatest reduction benefit, but a 20% blend of biodiesel (B20) can also substantially improve air quality.

	% Change from Regular Diesel
	B20	B100
Particles (also called particulates)	-12%	-47%
Total Unburned Hydrocarbons	-20%	-67%
Carbon Monoxide	-12%	-48%
Nitrogen Oxides	+2% to +4%	+10%
Greenhouse gases/ global warming		-~80%
Sulfates	-20%*	-100%
Polycyclic Aromatic Hydrocarbons	-13%**	-80%

* Estimated from B100 result;
**Average reduction across all compounds measured

Advantages

• Renewable. Diesel comes from petroleum, a non-renewable resource whose supplies are dwindling. Biodiesel is produced from oilseed crops, animal fats and waste cooking oils.
• Cleaner. Emissions from biodiesel are far cleaner than diesel. Pure biodiesel is nontoxic and spills biodegrade easily in soil and water.
• Reduces waste. Biodiesel reduces waste oils that otherwise would have to be disposed.
• Locally produced. Diesel is refined from petroleum oil, much of it is imported from other countries. Biodiesel can be grown and produced in Oregon, supporting local farmers and local economies.
• Energy Efficient. It takes energy to produce fuels like diesel and biodiesel. A life cycle analysis of diesel conducted by the US Department of Energy and US Department of Agriculture shows that it takes more energy to drill, transport and refine diesel than it produces when combusted. Petroleum diesel use results in a net energy loss of 19.5%. Biodiesel produces 3.2 units of fuel for every unit of energy consumed throughout its life cycle, creating a net energy gain of 220%.
• Easy to use. Biodiesel can be used with current fueling infrastructure and in all diesel vehicles with few or no engine modifications.

Disadvantages

• Cold weather. Some users report problems getting biodiesel to "flow" in close to freezing temperatures.
• There is a slight increase (2-4% depending on the blend) in NOx (forms smog). Researchers are working on additives to address the problem.

Solvent properties: Solvent properties of higher biodiesel blends can either be an advantage, as an additive to lower sulfur conventional diesel for biodiesel's lubricity, or a disadvantage as higher biodiesel blends may cause premature wear of natural rubber parts such as engine seals and hoses and clog fuel filters.

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