As part of a broad-reaching clean air program, California has proposed a low-NOx engine standard for heavy trucks. Another part of its plan is to push the Environmental Protection Agency for a nationwide low-NOx engine standard. But truck and engine makers have said in the past that striving for low NOx in diesels could conflict with federal efforts to reduce greenhouse gas emissions by increasing fuel economy.

The California Air Resources Board’s Proposed 2016 State Strategy for the State Implementation Plan (State SIP Strategy) released this week describes proposed measures needed to meet federal ozone and PM2.5 standards over the next 15 years.

Among its proposed measures is a Low-NOx Engine Standard to be developed between 2017 and 2019 with implementation starting in 2023. The goal, it said, is to introduce near-zero-emission engine technologies to lower oxides of nitrogen (NOx) emissions from on-road heavy-duty vehicles.

CARB said it may also petition the EPA this year to establish new federal heavy-duty engine emission standards.

“While U.S. EPA is reluctant in [GHG] Phase 2 [regulations] to push a low NOx standard, the fact that it's inevitable that California mandates it will place great pressure on the feds to follow suit,” says Joe Rajkovacz, spokesman for the Western States Trucking Association. “In my opinion, manufacturers would rather see a single national standard instead of needing to build two different engines.”

The State SIP Strategy is part of the larger California Sustainable Freight Action Plan, a multi-agency effort unveiled earlier this month. The plan, drafted in response to an executive order by Gov. Jerry Brown, lays a foundation for modernizing California’s multi-billion dollar freight transportation system. 

That executive order called for a target of deploying 100,000 freight vehicles and equipment capable of zero-emission operation and maximize near-zero emission freight vehicles and equipment powered by renewable energy by 2030.

CARB’s part of the plan, among other things, aims to cut smog-forming emissions from mobile sources in the South Coast area by 80% by 2030 compared to today — and to further cut particulate emissions from diesel truck engines by 45%.

California is the only state with the authority to adopt and enforce emission standards for new motor vehicle engines that differ from the federal emission standards.

CARB said its existing mobile-emissions regs will reduce NOx emissions in 2031 by more than 50% from today’s levels. These current programs will also result in significant reductions in PM2.5 emissions. This will bring most of the state into attainment with EPA standards — except for meeting ozone standards in the South Coast, and PM2.5 standards in the San Joaquin Valley.

NOx is the primary component of the smog that plagues the Los Angeles area.

NOx vs. Fuel Economy

HDT has contacted engine makers for comment and will follow up with a more detailed report. However, there has been acknowledgement for some time that this was brewing, and they have expressed concerns in the past.

Dan Kieffer, director of emissions compliance for Paccar, said in a public hearing on federal proposed emissions rules in California last summer, "Technology that reduces the engine work required to complete a mission, such as improved aerodynamics or reduced rolling resistance, inherently results in a proportionate reduction in total NOx output. This is not the case with engine efficiency improvement, where there is a well-documented trade-off between NOx reduction and engine efficiency.”

Kiefer was speaking on behalf of Daimler, Navistar, Volvo and Paccar at a Long Beach, Calif., hearing called by the U.S. Environmental Protection Agency and National Highway Traffic Safety Administration on their jointly proposed greenhouse gas emissions and fuel efficiency standards for medium- and heavy-duty trucks.

Alternative Fuels

The measure likely will provide a boost for natural gas and other alternative fuels and powertrains in the state.

Cummins Westport offers a low-NOx 8.9-liter natural gas engine, for instance. And earlier this year, UK-based Ricardo Inc. announced it will partner with the Gas Technology Institute to design natural gas engines for medium-duty vehicles that will emit less NOx.

In addition, the alternative fuel dimethyl ether, better known as DME, which Volvo is researching as a fuel that can be used in diesel engines without a lot of modification, is said to produce lower levels of NOx.

Electric and electric-hybrid powertrains will also be part of the plan, at the very least through incentive programs.

Beyond NOx

The low-NOx engine standards are only part of what CARB has in mind to meet the goals laid out in the sustainability plan.

Part of the plan also includes the new round of medium and heavy-duty vehicle and engine GHG emission standards, known as Phase 2, which will build upon the Phase 1 standards adopted federally in 2011 and in California in 2013. The federal Phase 2 standards are expected to be finalized this summer and to take effect with model year 2021 for all new Class 2b-8 medium- and heavy-duty trucks.

For the first time, the federal government has included trailers in its GHG regulations. Those are expected to go into effect in model year 2018 for new trailers. This will only apply to box-type trailers, which California has required for some time.

However, CARB said it may propose more stringent, California-only provisions, including layering additional requirements for vocational vehicle aerodynamics. We could see GHG emission reduction requirements for other trailer types, such as flatbed, tanker, container, and curtainside.

Another part of the proposal would put in place standards for low-emissions diesel and require fuel producers to sell steadily increasing volumes of LED until it makes up 50% of total diesel sales by 2031.

CARB also would cut the amount of time that transport refrigeration units operate using internal combustion enginesw while parked at certain California facilities and other locations. Compliance options would include the use of commercially available hybrid electric TRUs, TRUs equipped with electric standby motors, and new cryogenic transport refrigeration systems.

For the first time, California plans to address emissions from “last mile delivery” trucks – fleets, mostly Class 3-6 trucks, but some Class 7s, predominately used in urban areas to deliver freight from warehouses and distribution centers to the final point of sale or use (last mile delivery).

You can find a copy of the draft State SIP Strategy on CARB's website. There is a 45-day public comment period; CARB has scheduled a public board for Sept. 22 to consider the plan.

Related: California Aims to Regulate Sustainability into Freight System