How do biodiesel emissions compare to petroleum diesel?

Biodiesel is the only alternative fuel to have fully completed the health effects testing requirements of the Clean Air Act. The use of biodiesel in a conventional diesel engine not equipped with new diesel aftertreatment results in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from diesel fuel. In addition, the exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are essentially eliminated compared to higher sulfur diesel.

Biodiesel emissions compare to petroleum diesel

Of the major exhaust pollutants, both unburned hydrocarbons and nitrogen oxides are ozone or smog forming precursors. The use of biodiesel in diesel engines not equipped with new diesel aftertreatment results in a substantial reduction of unburned hydrocarbons. Emissions of nitrogen oxides are either slightly reduced or slightly increased depending on the duty cycle of the engine and testing methods used. Based on engine testing, using the most stringent emissions testing protocols required by EPA for certification of fuels or fuel additives in the US, the overall ozone forming potential of the speciated hydrocarbon emissions from biodiesel was nearly 50 percent less than that measured for diesel fuel. New Technology Diesel Engines (i.e. those with PM traps and SCR technology required for on-road applications in the US after 2010) reduce emissions of BOTH PM and NOx with B20 over 90% than 2004 model year and make NTDEs as clean or cleaner than either gasoline or natural gas fueled engines. And use of low carbon B20 in NTDEs make them the clean, green technology of the future.