Biodiesel Exhaust

Recent figures released by the National Biodiesel Board show that the use of biodiesel fuel has increased from 500,000 gallons in 1999 to 250 million gallons in 2006. Such dramatic increase raises the question as to how safe biodiesel exhaust emissions are. According to Biodiesel.org, "a 1998 biodiesel lifecycle study, jointly sponsored by the US Department of Energy and the US Department of Agriculture, concluded biodiesel reduces net CO2 emissions by 78 percent compared to petroleum diesel. This is due to biodiesel's closed carbon cycle. The CO2 released into the atmosphere when biodiesel is burned is recycled by growing plants, which are later processed into fuel."

Biodiesel exhaust emissions contain less particulate matter, carbon monoxide, and polycyclic aromatic hydrocarbons while sulfur-containing compounds appear to be undetectable. Nonetheless, the combustion of biodiesel in a diesel engine typically does increase the release in nitrogen oxides, which, in addition to inducing potential health effects, have been identified as an ozone precursor.

The U.S. Environmental Protection Agency (EPA) has established a series of biodiesel exhaust emission standards for various on-road and off-road diesel engine types. These standards are intended to reduce specific components of diesel exhaust (such as nitrogen oxide and particulate matter concentrations) by decreasing fuel sulfur content and particle traps, among other methodologies; however, it is unclear how much decrease will be observed for many gas-phase components derived from petroleum and biodiesel combustion. With the knowledge we have now, it is safe to believe that biodiesel exhaust is a lot less harmful to the environment and the living beings in it than petroleum diesel and that it is very desirable that the latter gets off the road as soon as possible. After all, the original diesel engine was actually designed to run on peanut oil. In terms of health, there is scientific evidence that diesel exhaust has a less harmful impact than petroleum diesel fuel, with little effect on human cells. In contrast, petroleum diesel exhaust has been found to kill throat cells and other cell cultures. However, there's a consensus that more research is necessary into the effect that biodiesel exhaust can have on biologic systems.