Study: Ultra-Low NOx Natural Gas Engines Exceed Federal, State Emission Standards

By Lauren Tyler, NGT News.

The University of California, Riverside College of Engineering Center for Environmental Research and Technology (CE-CERT) and SoCalGas have announced the results of a new study on ultra-low emission natural gas heavy-duty engines.

According to UC Riverside, the study found that a Los Angeles County Metropolitan Transit Agency (Metro) bus equipped with an ultra-low emission natural gas engine performs significantly cleaner than its certification standards across all duty cycles.

Specifically, researchers tested the Cummins Westport ISL G near zero natural gas engine in a variety of conditions typical of a Metro bus. In all conditions, the engine performed even better than California’s toughest in the nation standard for smog-forming emissions.  In some driving conditions, the report finds, emissions were practically zero.

“We have tested two of the ISL G near-zero 8.9 liter engines, one in a refuse hauler and one in a Metro bus. In both cases, the NOx emissions were surprisingly low and 99 percent cleaner than the current standard and 99.96 percent cleaner than the 2004 standard,” says Kent Johnson, associate research engineer for CE-CERT and lead researcher on this study.

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