Winnipeg, Canada-based bus manufacturer New Flyer of America will offer the Cummins Westport ISL G Near Zero (ISL G NZ) compressed natural gas (CNG) engine on its Xcelsior line of transit vehicles. The first installation of the low-NOx engine will be on a New Flyer Xcelsior XN40 bus to be delivered to the Los Angeles County Metropolitan Transportation Authority (LA Metro), which operates a large natural gas-powered transit vehicle fleet.

Cummins Westport says the ISL G NZ will be one of the first mid-range engines in North America to receive certification to meet the 0.02 g/bhp-hr optional near-zero NOx emissions standards from both the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board. According to the company, this certification represents a 10-fold emissions reduction below current EPA nitrogen oxide (NOx) emissions standards.

The ISL G Near Zero engine features closed-crankcase ventilation to reduce engine-related methane emissions. Image credit: Cummins Westport. The ISL G NZ's emissions are 90% below the U.S. federal particulate matter (PM) standard and 16% below the C02 emissions standard, the company says. The engine features closed-crankcase ventilation, which Cummins Westport says reduces engine-related methane emissions by 70%.

In addition to CNG, the ISL G NZ can operate on liquefied or renewable natural gas (RNG). Also known as biomethane, RNG is chemically identical to fossil natural gas, but yields fewer greenhouse emissions during the production process.

“RNG is a pipeline-quality gas that’s fully interchangeable with conventional natural gas, yet can be produced by reusing waste products," says Chris Stoddart, New Flyer vice president of engineering and customer services. It can be produced from landfills, livestock operations and wastewater treatment.