Through its just-announced Cleaner Trucks Initiative (CTI), the U.S. Environmental Protection Agency aims to further decrease nitrogen oxide (NOx) emissions from on-highway heavy-duty trucks and update a current engine exhaust standard in an early-2020 rulemaking. Set in 2001, the standard culminated in 2010 with a 0.2-gram brake-horsepower-hour NOx threshold for which engine manufacturers deployed selective catalytic reduction (SCR) equipment and urea-based diesel exhaust fluid (DEF). SCR injects DEF into the engine exhaust stream; the ensuing chemical reaction converts NOx into nitrogen, water vapor and traces of carbon dioxide.
|The post-EPA 2010 era has yielded single exhaust aftertreatment packages combining nitrogen oxide-treating selective catalytic reduction and diesel exhaust fluid dosing devices with diesel particulate filters. Volvo Trucks North America offers the One-Box Exhaust Aftertreatment System for VHD and companion models.|
CTI will see EPA streamline compliance and certification requirements tied to any new NOx threshold through a “deregulatory” focus on onboard diagnostic requirements; cost-effective means of reassuring compliance by using modern and advanced technologies; deterioration factor testing process; and, concerns regarding annual engine family recertification.
|Although geared to off-highway machines, the new Caterpillar C13 engine exhibits similar methodology to the Volvo One-Box (page 10): It utilizes SCR and diesel oxidation catalyst, plus a DPF; attains EPA Tier 4 emissions thresholds without the need for exhaust gas recirculation; and, is equipped with NOx sensors to reduce interface connections.|
“The Initiative will help modernize heavy-duty truck engines, improving efficiency and providing cleaner air for all Americans,” said Acting EPA Administrator Andrew Wheeler, who unveiled the CTI in an early-November gathering with the American Trucking Associations, equipment manufacturers and industry stakeholders. “The U.S. has made major reductions in NOx emissions, but it’s been nearly 20 years since EPA updated these standards. Through rulemaking and a comprehensive review of existing requirements, we will capitalize on these gains and incentivize new technologies to ensure heavy-duty trucks are clean and remain a competitive method of transportation.”
“[CTI] makes clear that reducing NOx emissions from heavy-duty vehicles is a clean air priority for this administration,” added EPA Office of Air and Radiation Assistant Administrator Bill Wehrum.
NOx emissions dropped by more than 40 percent from 2007 to 2017, owing partly to the advent of SCR exhaust aftertreatment on heavy-duty trucks. But there is more work to be done, contends EPA, citing estimates that such vehicles will be responsible for one-third of the transportation sector ‘s NOx emissions in 2025. The agency expects that any update to the standards will result in significant mobile source NOx reductions, assisting communities across the country in ozone and particulate matter standards attainment.
DIESEL TECHNOLOGY FORUM CONCURRENCE
The Diesel Technology Forum, Frederick, Md., responded positively to the Environmental Protection Agency Cleaner Trucks Initiative launch, observing:
Diesel has long been the technology of choice for the commercial vehicle sector, thanks to its continuous improvement and unique combination of energy efficiency, power and performance, reliability and durability, and most recently, achievement of near-zero emissions. CTI will help bring today’s generation of diesel even nearer to zero emissions than ever before.
The trucking industry continues to invest in the newest generation of advanced diesel technology in record numbers, sending a strong statement about its commitment to diesel power, even among a growing list of alternatives. As a result, today in the U.S. more than 36 percent of all registered operating diesel-powered commercial vehicles are of the newest generation of technology (2011 and newer model years). This is up from 30 percent in 2016, as confirmed by the Diesel Technology Forum’s recent analysis of 2017 U.S. vehicles in operation data (GVW 3-8). As these newest trucks take to American roads, they rack up significant societal benefits. Today, the more than 4.9 million new-generation diesel trucks on the road have removed more than 26 million tonnes of NOx and 59 million tonnes of carbon dioxide compared to previous generations.
Even as manufacturers explore other fuels and technology options, continued investments in diesel are strong indicators about the future for advanced diesel engines. Diesel remains the most energy-efficient internal combustion engine, one that offers an unmatched number of choices in size and performance for the broadest range of commercial vehicle operations. Along with near-zero emissions performance, choosing diesel ensures endless flexibilities in routing and operations to meet the ever-changing needs of customers. With well-established service and refueling networks across the United States to ensure maximum uptime, diesel is the proven partner in today’s overnight, same-day, just-in-time delivery world.
At this stage of the process, there are many aspects to be developed, but truck and engine makers, government, and user groups have the track record of history on our side to work together to realize this important vision that will drive the commercial trucking sector to even lower emissions, using the most advanced diesel and other technologies.