May 14, 2011

Biodiesel leading the way on cleaning up diesel exhaust

In advance of a congressional hearing on diesel emissions Thursday, the National Biodiesel Board (NBB) is highlighting the significant health and air quality improvements from blending biodiesel with petroleum diesel.

Emissions from traditional diesel - primarily from trucking fleets, school buses and other vehicles - are a significant health and air quality concern. In an update to its National-Scale Air Toxics Assessment earlier this year, the Environmental Protection Agency (EPA) cited diesel exhaust as one of the nation's most dangerous pollutants, saying it is "among the substances that may pose the greatest risk to the U.S. population."

Biodiesel is a clean-burning replacement fuel that can be used in existing diesel engines. Made from renewable sources such as vegetable oils, recycled cooking grease and animal fats, it is the first and only commercial-scale fuel widely used today that meets the Environmental Protection Agency's definition as an Advanced Biofuel. Along with significant reductions in greenhouse gas emissions, it dramatically reduces nearly every major toxic air pollutant, according to the EPA.

"Thousands of trucks and buses hit the road every day burning traditional diesel fuel, and using larger amounts of diesel fuel blended with biodiesel is the simplest, most effective way to immediately improve emissions," said Ben Evans, NBB's director of federal communications. "Along with creating U.S. jobs and reducing our reliance on foreign oil, improving air quality is a major reason why domestically produced biodiesel must play a critical role in the nation's fuel mix."

According to the EPA, biodiesel has the following emissions properties compared with petroleum diesel:

  • Carbon Monoxide - The exhaust emissions of carbon monoxide (a poisonous gas) from biodiesel are on average 48 percent lower than carbon monoxide emissions from diesel.

  • Particulate Matter - Breathing particulate has been shown to be a human health hazard. The exhaust emissions of particulate matter from biodiesel are about 47 percent lower than overall particulate matter emissions from diesel.

  • Hydrocarbons - The exhaust emissions of total hydrocarbons (a contributing factor in the localized formation of smog and ozone) are on average 67 percent lower for biodiesel than diesel fuel.

  • Sulfur emissions - The exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are essentially eliminated compared to diesel.

  • Nitrogen Oxides - NOx emissions from biodiesel increase or decrease depending on the engine family and testing procedures. NOx emissions (a contributing factor in the localized formation of smog and ozone) from pure (100%) biodiesel increase on average by 10 percent. However, biodiesel's lack of sulfur allows the use of NOx control technologies that cannot be used with conventional diesel. Additionally, some companies have successfully developed additives to reduce NOx emissions in biodiesel blends. Biodiesel reduces the health risks associated with petroleum diesel.

  • Biodiesel emissions show decreased levels of polycyclic aromatic hydrocarbons (PAH) and nitrated polycyclic aromatic hydrocarbons (nPAH), which have been identified as potential cancer causing compounds. In Health Effects testing, PAH compounds were reduced by 75 to 85 percent, with the exception of benzo(a)anthracene, which was reduced by roughly 50 percent. Targeted nPAH compounds were also reduced dramatically with biodiesel, with 2-nitrofluorene and 1- nitropyrene reduced by 90 percent, and the rest of the nPAH compounds reduced to only trace levels.

Visit the National Biodiesel Board website for the full written testimony submitted to the Senate Committee on Environment and Public Works.

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