Environmental benefits in comparison to petroleum based fuels include:

• Biodiesel reduces emissions of carbon monoxide (CO) by approximately 50% and carbon dioxide by 78.45% on a net lifecycle basis because the carbon in biodiesel emissions is recycled from carbon that was already in the atmosphere, rather than being new carbon from petroleum that was sequestered in the earth's crust. (Sheehan, 1998)
• Biodiesel contains fewer aromatic hydrocarbons: benzofluoranthene: 56% reduction; Benzopyrenes: 71% reduction.
• It also eliminates sulfur emissions (SO₂), because biodiesel doesn't include sulfur.
• Biodiesel reduces by as much as 65% the emission of particulates (small particles of solid combustion products).
• Biodiesel does produce more NOx emissions than petrodiesel, but these emissions can be reduced through the use of catalytic converters. Petrodiesel vehicles have generally not included catalytic converters because the sulfur content in that fuel destroys the devices, but biodiesel does not contain sulfur. The increase in NOx emissions may also be due to the higher cetane rating of biodiesel. Properly designed and tuned engines may eliminate this increase.

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