Advances in diesel technology point to cleaner air

Published August 1, 2001

On May 8, International Truck and Engine Corporation (ITEC) released “Performance, Environment, Safety, Health: The Facts About New Diesel Technology.” According to the report, ITEC’s new Green Diesel Technology reduces particulate emissions to levels at or below emissions produced by environmentalist-championed natural gas.

Green Diesel Technology makes possible the nation’s first smokeless, odorless diesel school bus, entering the market this year.

Central to the success of Green Diesel Technology is ultra-low-sulfur diesel fuel. BP, Equilon, and Tosco have committed to producing the fuel, which is already commercially available in California. ITEC expects ultra-low-sulfur diesel fuel to soon be commercially available across the nation as a whole.

According to the report, the new diesel bus engine emits just one-fifth the particulate matter and one-fourth the hydro-carbon of natural gas engines. The new engine also results in lower greenhouse gas emissions due to its greater fuel mileage (diesel engines use between 40 and 60 percent less fuel per mile than natural gas engines, according to the report) and its lack of methane emissions during refueling.

The bane of diesel engines has traditionally been their heightened release of nitrogen oxide (NOx). Natural gas engines in the past have produced 25 to 75 percent fewer NOx emissions than diesel engines. However, the new diesel bus engine has gained approximate parity with natural gas engines, producing only 11 percent more NOx than its natural gas counterparts. When this small differential is placed in the context of the diesel engine’s significant advantages regarding other pollutants, the new engine is clearly the “greener” technology, asserts ITEC.

While natural gas advocates have in the past attacked diesel engines as risky to human health, due to their particle emissions, research has failed to support that assertion. ITEC notes the significantly reduced emissions in its new Green Diesel Technology makes any such attacks obsolete.

Greener automobiles

Researchers at the U.S. Department of Energy’s Pacific Northwest National Laboratory (PNNL) have developed a way to cut in half the NOx emissions from diesel automobile engines. The reduction is achieved by combining an electrically charged gas, called plasma, with a specialized catalyst. The process converts harmful NOx emissions to pure nitrogen–a component of clean air.

“Our scientists began looking at various materials and found a specialized catalyst that selectively reduces oxides of nitrogen,” stated Chuck Peden, principal investigator for the project, in a press release issued by PNNL. Those initial laboratory studies showed the process reduced NOx by 70 percent. “But our lab results over the past six months now show that greater than 90 percent reduction can be achieved,” Peden said.

“We continue to make progress toward achieving the goals with this technology,” said Peden. “There is more work to be done to reduce the amount of electrical power required to operate the reactor and to increase the overall NOx reduction from 50 to 90 percent on a real engine.”

“Clean diesel technology shows exceptional promise in improving the environmental performance of cars and trucks,” notes Joseph Bast, president of The Heartland Institute and coauthor of a Heartland Policy Study on fuel and engine technologies. “Diesel vehicles can match or exceed the environmental achievements of alternatives while maintaining a significant edge in terms of cost, safety, and performance.”

With ongoing advances in clean diesel technology, consumers may not have to sacrifice performance and price for a healthy environment.

For more information . . .

The full text of International Truck and Engine Corporation’s “Performance, Environment, Safety, Health” report is available on the Internet at

Heartland Policy Study No. 95, “The Increasing Sustainability of Cars, Trucks, and the Internal Combustion Engine,” is available on the Internet at