Cummins Westport has announced field-testing of a spark-ignited natural gas engine capable of producing near zero NOx emissions ahead of the 2023 California Near Zero NOx schedule for low NOx vehicles.

The testing will begin this year in California on transit buses. The Near Zero NOx technology is being tested in the ISL G engine and will be made available as a first fit engine with transit and refuse OEMs as a replacement for existing ISL G vehicles.

CWI believes its Stoichiometric EGR spark ignited natural gas engine technology is suited to meeting California’s air quality improvement initiatives. The SESI technology was a part of the recently announced ISB6.7 G natural gas engine and is also a part of the ISL G and ISX12 G engines.  

With funding support from South Coast Air Quality Management District, SoCal Gas and California Energy Commission, CWI said it invested significantly on leveraging the SESI platform to develop a new Near Zero NOx technology pathway to reducing emissions by 90% from 0.2 to 0.02 grams per brake horsepower NOx.

The technology will also meet the 2017 EPA greenhouse gas emission requirements, according to CWI. Commercial availability will be announced at a later date.

The new ISL G will also include Three-Way Catalyst passive aftertreatment, packaged as part of the muffler. Cummins Westport natural gas engines do not require active aftertreatment such as a diesel particulate filter or selective catalytic reduction.

The ISL G 8.9-liter engine was introduced in 2007 and has been used primarily in transit buses and refuse trucks.