2nd May 2001
©2001, Environmental News Network
Permission obtained on 1st August 2001. Jerry Kay (news@enn.com). E-mail message.

A breakthrough in pollution emissions technology at a U.S. national laboratory signals the day when a new class of vehicles will travel up to 80 miles on a gallon of fuel while meeting reduced emissions levels for nitrogen oxides, carbon dioxide and hydrocarbons. 

By combining an electrically charged gas with a specialized catalyst, researchers at the Department of Energy's Pacific Northwest National Laboratory have successfully reduced harmful oxides of nitrogen in a diesel engine by 50 percent. 

A patent is pending on a class of zeolite catalyst materials that appear to be the key to nitrogen oxide, or NO_x, reduction in this novel approach to the control of harmful vehicle exhaust emissions. 

"This technology, if successful, will reduce NO_x and particulate emissions and enable the use of high-fuel economy diesel vehicles that will help relieve our dependence on foreign oil," said Kathi Epping, program manager for Combustion and Emission Control Program in the DOE Office of Energy Efficiency and Renewable Energy's Office of Transportation Technologies, which is funding this research.

As part of the United States Council for Automotive Research's Low Emissions Technologies Research and Development Partnership, the scientists are helping to develop a vehicle envisioned by the Partnership for a New Generation Vehicle. 

Ford, General Motors and DaimlerChrysler, under the umbrella of USCAR, are working together on technological and environmental concerns. 

USCAR formed Partnership for a New Generation Vehicle with the federal government in 1993 to develop technologies for a new generation of fuel-efficient, cleaner vehicles. 

The foundation for this research began several years ago when PNNL scientists showed that an electrically charged gas, called plasma, along with a catalyst, could convert nitrogen oxides to nitrogen, a component of clean air. They developed a small reactor to house the plasma reaction and quickly discovered that the packing material used in the reactor affected the chemical reaction. 

"Our scientists began looking at various materials and found a specialized catalyst that selectively reduces oxides of nitrogen," said Chuck Peden, principal investigator for the project. The initial laboratory studies showed that 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. 

Ground-level ozone, or smog, is formed when nitrogen oxide and volatile organic compounds such as gasoline vapors react in the presence of heat and sunlight. Inhaling smog results in lung damage, aggravation of existing heart disease and premature death, according to the U.S. Environmental Protection Agency. 

Laboratory tests also have shown the new technology has the potential for significant soot reduction. The soot portion of exhaust consists of tiny particles of carbon and organics that are potentially harmful to human health because they lodge deep in the lungs where they contribute to respiratory disease.

New hybrid, light-duty diesel engines, such as those used in passenger cars and small trucks, already meet target fuel economy requirements and emit less of the greenhouse gas carbon dioxide than gasoline engines. 

But unlike gasoline engines, there is no technology that can sufficiently reduce nitrogen oxides in the lean-burn exhaust typical of diesel vehicles. Nitrogen oxides cause air pollution. 

"Combining the plasma reactor concept with a catalyst was considered to be a left-field approach, but it is now moving to the top of the PNGV list," said Steve Barlow, a chemical physicist at Pacific Northwest National Laboratory in Richland, Washington.

"Six years ago, this field of non-thermal plasma activated catalysis didn't exist, but it appears to have many advantages over competing technologies. For example, our catalysts aren't poisoned by sulfur in the exhaust, which is a challenge for other catalytic technologies," Barlow explained.

Recent prototype reactor tests conducted on a diesel engine at DOE's Oak Ridge National Laboratory show a 50 percent reduction of NOx. Researchers are continuing to refine the plasma reactor system, which received a patent in 1999, to achieve an even greater reduction of NOx. PNGV targets are a 90 percent reduction in NOx emissions at 80 miles per gallon. 

"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."

One proposed timeline for integrating the emission reducing reactors comes from PNGV. The company hopes to have a prototype vehicle by 2004.