Low NOx Natural Gas Engine Development for Heavy-Duty Vehicles

The first production heavy-duty engine certified to near-zero NOx emission levels

South Coast Air Quality Management District


Diamond Bar, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

Work for this agreement was completed on June 30, 2016. The 8.9 liter engine was certified at the low NOx level and has been made commercially available.

The Issue

Natural gas vehicle technology currently has a high potential for greenhouse gas reductions of 11 to 23 percent on a well-to-wheels basis in heavy-duty vehicles using conventional natural gas. The on-road demonstration of these prototype natural gas engines is an important step toward commercialization of near-zero emission technology. The reductions in NOx emissions from heavy-duty vehicles is necessary for California’s worst air basins to attain National Ambient Air Quality Standards for ozone and will support the state’s climate change policies.

Project Innovation

This project supported the development a Near Zero 8.9-Liter natural gas engine suitable for use in various heavy-duty vehicle applications that achieve a 90% reduction in NOx emissions. This project also supported the development of a low-NOx design concept for a 15-Liter natural gas engine. While the 15-liter engine has not been commercialized, design concepts can be utilized for future advanced low-NOx natural gas engine development.

Project Benefits

This project successfully exceeded the target goal of 90% emissions reductions achieved 0.01 g/bhp-hr of NOx. This near-zero 8.9-liter engine was certified at the optional low-NOx level of 0.02 g/bhp-hr. CWI's 8.9-liter NG currently accounts for 46% and 33% of the refuse and transit markets respectively, and NOx emissions will be reduced by approximately 2.2 tonnes per day in the South Coast Air Basin alone.

Consumer Appeal

Consumer Appeal

CARB has found that low-NOx trucks are the most viable approach to meet California’s goals to attain NAAQS for NOx and PM2.5. It is technically and economically feasible to deploy 400,000 near zero-emission HDVs by 2030, and large-scale deployment of low-NOx goods movement will provide the largest health benefit of any single new strategy.

Environmental & Public Health

Environmental Sustainability

This project will result in the deployment of new near-zero natural gas engines with lower emissions, including a 90% reduction in smog forming NOx emissions. This will contribute to an improvement in air quality as these engines are deployed and replace the existing 8.9-liter engines.

Key Project Members

Project Member

Jeff Cox

Project Manager & Administrator



Cummins Westport, Inc.


Cummins Inc.


Match Partners


Southern California Gas Company (SoCalGas)


South Coast Air Quality Management District


Contact the Team