September 16, 2020

Purdue research drives efforts toward cleaner air in California

WEST LAFAYETTE, Ind. — Purdue University research is driving clean air changes in California and could lead to landmark vehicle emissions changes across the United States.

The California Air Resources Board’s new rules phase in tougher standards on emissions to protect communities near heavy truck traffic areas where the heavy-duty vehicles often idle or move slowly, creating increased smog emissions.

Gregory Shaver, a Purdue professor of mechanical engineering, said California’s regulations often drive progressive change across the United States, and around the globe. He is part of a national effort to reduce carbon dioxide, nitrogen oxide and microscopic particle emissions as well as vehicle fuel consumption.

Shaver led the research efforts at the Ray W. Herrick labs. He worked with Purdue industry collaborators Cummins and Eaton, building on a collaboration he started with Cummins dating to 2006.

“Research done here at Purdue was essential to demonstrating that it is possible to simultaneously reduce the fuel consumption and tailpipe emissions of diesel-powered trucks – key findings that helped the California Air Resources Board take this bold step to reduce tailpipe nitrogen oxide emissions by another 90%,” Shaver said.

Shaver’s research collaboration with the U.S. Department of Energy and industry has enabled diesel engine efficiency and emissions control through variable valve actuation (VVA). VVA allows for increased efficiency of diesel engines, also called compression ignition engines, by utilizing cylinder deactivation, and other methods, during engine idling, low-load operation and highway cruise conditions. VVA also enables the faster warm-up of catalysts for effective reduction of engine-out nitrogen oxides and microscopic particle emissions.

California’s new Heavy-Duty Engine and Vehicle Omnibus Regulation is to be phased in from 2024 through 2031. The expected result is the reduction of harmful oxides of nitrogen, a key component of smog, according to the air resources board. The emission reductions in 2031 are estimated at 23 tons per day, the same as removing 16 million light-duty cars per day from the road.

The air resource board reports, Shaver said, describe the efforts and makes direct reference to seven of Purdue’s peer-reviewed research papers on the topic. 

He expects significant positive and long-term impacts for the environment, as industry leaders adopt these standards in their engine technologies and export them globally.

“This will be a fair, but very difficult, emissions regulation for the industry to meet,” Shaver said. “It will save lives, improve air quality and accelerate the development and implementation of advanced technologies.”

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Writer, Media contact: Brian Huchel, 765-494-2084,

Source: Gregory Shaver, 765-494-9342,

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