|
 iesel fuel made from natural renewable sources such
as vegetable oils or animal fats lowered air-polluting emissions
of heavy trucks in a trial study, according to researchers. They
say the so-called "biodiesel" fuel can be used in regular
diesel engines without modifying them.
 The
finding is reported in the March 1 print edition of the journal
Environmental Science & Technology by researchers
from West Virginia University (WVU) in Morgantown, WV, and the
National Renewable Energy Laboratory in Golden, CO. It was initially
published on the journal's web site on Feb. 9. The peer-reviewed
journal is published by the American Chemical Society, the world's
largest scientific society.
"Biodiesel
fuel may have the potential to reduce our nation's reliance on
imported oil and to improve air quality," said Mridul Gautam,
PhD, a professor in the university's Department of Mechanical
and Aerospace Engineering and one of the authors of the study.
The scientists studied a blend of 35 percent biodiesel fuel and
65 percent conventional diesel fuel. They found that this emitted
significantly less carbon monoxide and moderately less hydrocarbons
and particulate matter, compared to 100 percent petroleum diesel.
"The
potential of biodiesel to reduce emissions is quite significant,"
says Gautam. "There is a 25 percent reduction in particulate
emissions alone." Emissions of carbon monoxide declined
by 12 to 14 percent, and hydrocarbons by 10 percent, he added.
Biodiesel
fuel is made by a reaction of vegetable oils with methanol or
ethanol. The result is a less viscous, more volatile fuel. The
truck engines ran just as efficiently on the biodiesel mix as
on conventional diesel fuel (i.e., the average miles per gallon
were essentially the same). The research team found slightly
elevated levels of nitrous oxide (NOX) emissions with the biodiesel
blend. Changing the ignition timing of the engines reduced NOX
emissions.
The reduction
in carbon monoxide emissions is probably due to the higher oxygen
content of the biodiesel fuel, the researchers say. More oxygen
means the fuel is burned more completely. More complete burning
also helps reduce hydrocarbon emissions.
The researchers
attributed the 25 percent reduction in particulate emissions
to the lower aromatic and sulfur content of biodiesel fuel, and
its greater oxygen content.
The biodiesel
study at West Virginia University was funded by the United States
Department of Energy's Office of Transportation Technologies.
The research team also included WVU scientists Donald W. Lyons,
Nigel N. Clark and Wen-Guang Wang (now at Ford Motor Company
in Dearborn, Mich.) and Paul Norton from the National Renewable
Energy Laboratory. 
|
