Group enlightens EPA on new diesel engines’ indispensable role in cleaner air

During the first of three hearings on updated national air quality standards for ground-level ozone, Diesel Technology Forum Executive Director Allen Schaeffer told U.S. Environmental Protection Agency officials that new engine technology and accelerated upgrades to existing vehicles and equipment will be important in meeting future thresholds. EPA has proposed to strengthen ozone standards to a level within a range of 65 to 70 parts per billion to further reduce national air quality issues, while also taking comments on a level as low as 60 ppb.


Reserving comment on the proposed changes, Schaeffer highlighted how the cooperative working relationship between EPA, national environmental and health organizations and manufacturers had resulted in significant improvements to diesel efficiency and reduced emissions. “Diesel engines are a declining contributor to the national inventory of nitrogen oxides, a key ozone precursor,” he says. “The increasing utilization of new technology clean diesel engines will play the most important role in assuring continued progress toward both clean air and climate objectives … The diesel industry is building on these clean air accomplishments and now increasingly focused on producing near-zero emissions technology that also is more efficient and has lower greenhouse gas emissions as well.”

Clean Air Progress

Impressive NOx emissions reductions accrue from over a decade of collaboration between technology leaders and the EPA in establishing a regulatory pathway for the introduction of clean diesel engines in on- and off-road applications, Schaeffer observes, adding: “Since 2000, manufacturers have been working to meet the challenge of virtually eliminating emissions from diesel engines. Today, manufacturers have met that challenge. First along the pathway were strict NOx emissions standards promulgated for the heavy-duty on-road fleet beginning in model year 2007, and further tightened for model year 2010.”

Diesel Technology Forum-commissioned research indicates how the growing share of clean diesel-equipped, heavy-duty vehicles account for significant NOx emissions reduction. More than one-third of all commercial heavy-duty trucks nationwide are 2007 and newer, and about 16 percent are 2011 or later. “As of 2013, we estimate that these vehicles have reduced NOx by one million tons nationwide,” Schaeffer says. “In some regions and localities, the NOx emission reduction from clean diesel trucks has been even more substantial.

“Engine manufacturers and emissions control technology manufacturers have invested billions of dollars to reduce the formation of nitrogen oxide emissions through controlling of the combustion process itself as well as the use of selective catalytic reduction systems (SCR).”


Schaeffer informed the EPA panel of a number of unique approaches to reducing nitrogen oxide emissions from existing engines and equipment: “As of 2010, the Ports of Los Angeles and Long Beach require all of the roughly 16,000 trucks transiting through America’s largest port complex every day be deployed with an engine that meets the EPA model year 2007 emissions standard. The ports estimate that 90 percent of port trucks are powered with a diesel engine.

“Since that requirement, both ports estimate that NOx emissions attributable to port trucks have fallen by 92 percent since 2005. As a share of all NOx emissions in the region, port trucks’ [contribution] has fallen from a peak of about 42 percent in 2006 to about 17 percent in 2012, when the emissions inventory was completed. These are significant real world emission reductions that will benefit communities surrounding the port.

“Nationwide, as more of the truck fleet is turned over to new and newer vehicles deployed with a clean diesel engine, we can expect significant improvement in air quality attributable to the heavy-duty diesel powered fleet, similar to that experienced in southern California.”

Tier 4 Final

Schaeffer characterized 2014 as a “milestone year” for clean diesel in other applications, namely Tier 4 final requirements for off-road diesel technology. “Similar NOx emissions standards promulgated for the heavy-duty vehicles are now required of new engines found in most off-road applications, including construction, agricultural and other applications,” he says. “Construction equipment at work on a road or other public works project deployed with a Tier 4 final engine may contribute to NOx emissions reduction for a region or locality.”

In concluding thoughts, he cited the Diesel Emissions Reduction Act (DERA), which since its 2005 inception “has played a key role in catalyzing the move to new and cleaner diesel engines and equipment, and the modernizing and upgrading of existing engines and equipment. According to the most recent EPA Report to Congress, emissions of nitrogen oxide emissions have been slashed by over 203,000 tons thanks to funding provided by the DERA program between 2008 and 2010.”

— Diesel Technology Forum, Frederick, Md.;