California Pushes EPA to Lower NOx Limit as Part of GHG Rule for Heavy Trucks
California environmental regulators said they plan to begin development of tougher nitrogen oxide standards for heavy trucks, possibly as early as 2017.
The disclosure was included in written comments on the federal government’s Phase 2 greenhouse-gas proposal, which the California Air Resources Board said may actually cause NOx emissions to increase at a time the state is struggling to meet national ambient air quality standards.
“CARB expected the proposal to include commitment from the Environmental Protection Agency to begin efforts to develop lower mandatory NOx standards for heavy-duty engines and vehicles,” CARB wrote in its more than 150-page document.
If EPA and the National Highway Traffic Safety Administration fail to include NOx reduction strategies in its final Phase 2 rule, CARB said it will continue its efforts to establish a California-only standard and petition EPA to make the California standard a national requirement.
CARB already is offering incentives to researchers and manufacturers to demonstrate the feasibility of low-NOx emissions in natural gas- and diesel-powered heavy trucks without incurring a GHG penalty.
“Aftertreatment system manufacturers are also conducting research to develop technologies that would significantly improve the performance of the aftertreatment systems to reduce emissions during cold start, light load and high-speed steady-state operations, and the developments are showing promising signs that NOx can be reduced significantly below current standards,” CARB said. “Emissions from heavy-duty diesel engines can be significantly reduced utilizing a systems approach combining advanced aftertreatment systems with engine management strategies.”
CARB’s technology-assessment report concluded it is possible to require trucks in California to reduce the current 0.2 gram per brake horsepower-hour NOx emissions- level standard by as much as 70% by 2023 and 80% by 2031 to meet national air standards in several areas of the state. Ideally, CARB would like to see a 90% reduction by 2031.
“NOx emissions are real important to us because NOx is a main component in smog,” CARB spokesman Dave Clegern told Transport Topics. “We have two areas in the state, the San Joaquin Valley and the Los Angeles Basin, that have some of the worst air in the country, if not the worst air in the country. And NOx is a big factor there.”
Mike Tunnell, California-based director of environmental affairs for American Trucking Associations, said some areas of California have yet to meet EPA’s national ambient air quality standard for ozone at 75 parts per billion. EPA recently announced it is transitioning to a tougher standard — 70 ppb.
Ground level or “bad” ozone is not emitted directly into the air but is created by chemical reactions between NOx and volatile organic compounds in the presence of sunlight, EPA said.
“CARB is saying we need 80% NOx reductions to get there, and they’re looking to heavy-truck components to help reduce those emissions,” Tunnell said. “The million-dollar question is what levels can we get to?”
To answer that question, Tunnell said CARB is awaiting the results of NOx reduction testing by the Southwest Research Institute. The contractor is expected to report to CARB by the end of 2016 on what technologies would best achieve the targeted results.
Both CARB and Tunnell said those goals may be challenging since there typically is a trade-off between improved fuel economy — a goal of EPA’s greenhouse-gas rule — and NOx emissions.
In joint Phase 2 comments, heavy-truck makers expressed similar concerns.
“There is a well-established inverse relationship between carbon dioxide and oxides of nitrogen emissions from an engine,” the manufacturers wrote. “If engine CO2 emissions and fuel-economy consumption are to decrease, as is the intent of Phase 2 regulations, the engine-out NOx level must increase.”
EPA did not respond to a request for comment by press time.
