California to further reduce emissions from heavy-duty engines

23 February 2013

To meet its long-term air quality objectives, California must further reduce emissions from on-road heavy-duty vehicles. The California Air Resources Board (ARB) has been working to develop a “sustainable freight strategy” that would involve additional reductions in greenhouse gas (GHG) and NOx emissions.

While few details on the upcoming regulatory initiatives have been released, the ARB announced a public workshop on March 11, 2013, to discuss several planned regulatory actions related to on-road heavy-duty vehicles. At the workshop, the ARB staff will be soliciting input on the following proposals:

• Adopting a new regulation to harmonize with the GHG emissions standards for medium- and heavy-duty engines and vehicles that the US Environmental Protection Agency (EPA) adopted in 2011;
• Making amendments to ARB’s existing Heavy-Duty Vehicle GHG Emission Reduction Regulation (Tractor-Trailer GHG regulation) to align with the proposed new regulation above;
• Adopting a new set of optional NOx emission standards for heavy-duty vehicle engines more stringent than the current 2010 model year standard; and
• Making amendments to the Airborne Toxic Control Measure (ATCM) to Limit Diesel-fueled Commercial Motor Vehicle Idling to expand compliance responsibility.

In January, the ARB released its Annual Report to the Joint Legislative Budget Committee on Assembly Bill 32 (The California Global Warming Solutions Act of 2006). Commenting on the “upcoming milestones”, the report mentions a public symposium on zero/near-zero emission freight technology to be hosted by the South Coast Air Quality Management District in the Spring 2013. Later in 2013, ARB staff anticipates presenting concepts for development of a sustainable freight strategy to the Board. This activity will be reflected in an update to the AB32 scoping plan, as well as subsequent SIP revisions.

The need for further NOx emission reductions from heavy-duty engines was first signaled in the Vision for Clean Air draft report released in June 2012. The document estimated that for the South Coast Air Basin, NOx must be reduced by around 80% from 2010 levels by 2023, and almost 90% by 2032. Similar levels of emissions reductions are likely needed in the San Joaquin Valley by 2032. To achieve such emission reductions in heavy-duty diesel engines, the NOx emission standard would have to be tightened from the current 0.2 g/bhp-hr to possibly as low as 0.05 g/bhp-hr.

Such ultra-low NOx emission limit would make it very challenging to meet the current and future GHG and efficiency requirements. The anticipated proposals are likely to face opposition from engine manufacturers, the trucking industry and other freight-intensive industry sectors.

Source: California ARB