Cummins Westport’s new ultra-low emission heavy duty natural gas vehicle (NGV) engine has passed a series of “cleanliness” tests under various driving conditions.

A study by the University of California, Riverside’s College of Engineering Center for Environmental Research and Technology (CE-CERT) and Southern California Gas Co. (SoCalGas) demonstrated that the 11.9-liter engine achieved California’s lowest smog-forming emissions standard and maintained low emissions in all types of driving. The engine is the only heavy-duty engine in the category to exceed the California Air Resources Board (CARB) standards.

Similar testing on an 8.9-liter near-zero NGV engine last year found the smaller engine had even lower emissions than CARB standards will require in the near future, and in some driving conditions the emissions were almost zero, according to CE-CERT’s Kent Johnson, assistant research engineer.

Johnson said the smaller engine’s intended use is in school buses and refuse trucks, which are only about 30% of the heavy-duty inventory. The new, larger engine “is good not only for the smaller workforce applications of transit and refuse, but also for hauling loads around Southern California,” Johnson said.

SoCalGas, which has been working with the California Energy Commission (CEC) and others to help fleet operators switch to NGVs, emphasized that the transportation sector accounts for 80% of the smog-forming emissions in California.

“This type of near-zero pollution engine adds to the growing number of clean energy technologies being developed to reduce pollution in efforts to meet California’s clean air standards,” said CEC’s Janea Scott.

The study noted that additional nitrogen oxide (NOx) reductions of another 90% are desired by California’s South Coast Air Quality Management District (SCAQMD) to meet its 2023 inventory requirements. Generally, it is expected that NGVs “could play a significant role” in achieving the SCAQMD inventory goals, “given the near-zero emission factors demonstrated” by the research.

“To meet our air quality goals, we must continue to see improvements in the transportation sector, which contributes the most air pollution in our region,” said SCAQMD executive officer Wayne Nastri.

In other developments, trade group NGVAmerica noted that a smaller NGV low-NOx engine, Agility Fuel Solutions’ 6-liter engine, has received its first engine certification.

With General Motors assistance, the Agility 366NG engine with an Agility NGV fuel system was certified by the CARB Optional Low NOx Emissions Standards and greenhouse gas emissions standards. Agility also received the CARB heavy-duty on-board diagnostics certification with full compliance.

Agility’s engine is said to be suited for school bus, walk-in van, cutaway chassis, cabover, terminal tractor and medium-duty work truck applications in all 50 states, according to NGVAmerica President Dan Gage.

The engine is available to original equipment manufacturers on a standalone basis, or as a fuel system only and can be combined with Agility’s compressed natural gas storage solutions for Class 4-6 medium-duty vehicles.

Meanwhile, the Renewable Natural Gas (RNG) Coalition is hosting a technical workshop and trade exposition on Sept. 11-12 in Denver to discuss various applications, from transportation to the feedstock (livestock, agriculture and food processing) industry.