The United States Environmental Protection Agency says a West Virginia University study raised questions about emissions levels from light-duty diesel Volkswagen vehicles during on-the-road testing.
Results of the study conducted by WVU’s Center for Alternative Fuels, Engines and Emissions, or CAFEE, found that nitrogen oxide emissions – one of the top six common air pollutants – from two Volkswagen light-duty diesel engines exceeded the EPA’s Tier 2-Bin 5 standard. One vehicle exceeded the standard by a factor of 15 to 35 and the other by a factor of 5 to 20.
“CAFEE’s faculty, engineers, technicians and graduate students are conducting high-level research on emissions reduction,” said Daniel Carder, CAFEE’s interim director. “This study shows how data-driven, independent research can have real-world impact.”
In 2014, the International Council on Clean Transportation contracted WVU to perform on-road emissions testing in order to study off-cycle emissions performance and fuel economy from three diesel light-duty vehicles under typical driving conditions in the U.S.
Arvind Thiruvengadam, research assistant professor of mechanical and aerospace engineering in the Statler College of Engineering and Mineral Resources, carried out the real-word emissions testing.
In-use emissions testing is conducted by using a portable emissions measurement system and small generator or battery pack used to power the instruments. The system is a scaled-down version of laboratory-grade measurement equipment, the size of couple shoe boxes.
The PEMS is capable of characterizing carbon dioxide, carbon monoxide, oxides of nitrogen and hydrocarbon emissions from the tailpipe of a vehicle. In addition, the data broadcasted by the electronic control unit of the engine is also collected.
The test vehicle is driven like normal day-to-day operation or on specific routes of interest to evaluate the effect of traffic, road conditions, atmospheric conditions and terrain on emissions.
The test plan covered a wide variety of topological, road and ambient conditions as well as traffic densities over three major urban areas along the west coast – San Diego, Los Angeles and San Francisco.
“Real-world emissions evaluation is very important, because it provides a unique window into the operation of sophisticated engine controls, after-treatment technology and software strategies of modern vehicles during normal day-to-day operation that is seldom available from a controlled laboratory environment,” Thiruvengadam said.
As part of the project, the California Air Resources Board performed traditional laboratory testing to assess compliance with certification standards. The findings from in-use testing and laboratory testing were disseminated publicly.
Click below to hear the WVUToday radio spot about WVU's emissions research.
This is not the first time researchers at CAFEE have been involved in off-cycle emissions research. In the late 1990s, CAFEE was contracted to conduct in-use emissions testing for heavy-duty engines. As part of this work the center developed the world’s first mobile on-board diesel emissions testing system and pioneered the development of associated testing protocols necessary for accurate in-use emissions testing.
CAFEE’s research team of faculty, students, and technical staff is one of the most experienced in the nation in the characterization of emissions and the performance of heavy-duty vehicles.
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