Biodiesel is the first alternative fuel to have fully completed the Health Effects testing requirements in the U.S. Clean Air Act Amendments of 1990. The use of biodiesel in a conventional diesel engine results in a substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter.

• Biodiesel use decreases the solid carbon fraction of particulate matter (since the oxygen in biodiesel enables more complete combustion of CO₂)
• Biodiesel reduces net carbon dioxide (CO₂) emissions by 100%
• Biodiesel reduces soot emissions by 40-60%
• Biodiesel reduces carbon monoxide (CO) emissions by 10-50%
• The use of biodiesel reduces sulfur dioxide (SO₂) emissions by 100%
• Biodiesel reduces hydrocarbon (HC) emissions by 10-50%
• Biodiesel effectively eliminates all polycyclic aromatic hydrocarbons (PAHs)
• Biodiesel works well with new technologies such as catalysts, particulate traps, and exhaust gas recirculation
• Emissions of nitrogen oxides are either slightly reduced or slightly increased depending on the age of the vehicle and the tuning of the engine
• Biodiesel replaces the exhaust odor typical of petroleum diesel with the pleasant smell of french fries or donuts

See how pure biodiesel (B100) and biodiesel blend (B20) compare to conventional petroleum diesel in keeping our air breathable:

Information supplied by National Biodiesel Board.

* Biodiesel’s NOx emissions are the focus of current research, and the scientific community is reconsidering NOx contributions to smog. Based upon recently published results, former findings of NOx increases with biodiesel may not be accurate. The most recent research on the subject shows equal or decreased NOx emissions compared to diesel. For the most current findings on biodiesel NOx emissions see the August 2005 NREL Study.

Want to know more about emissions? Check out the EPA report: A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions