Changes will be coming to diesel truck engines during the next five to 15 years, and a key power player that will guide many of those developments is the California Air Resources Board.
Truck manufacturers, engine makers and drivers will endure the next round of emissions requirements and myriad technological failures and adjustments as new systems are tested on the pavement of the real world.
This week, CARB released a sketch of current NOx emissions from diesel big rigs and projected further development of technology needed for commercial trucks. The information was issued as a draft technology assessment.
Class 8 trucks are currently required to meet 2010 emission limits of 0.2 grams per brake horsepower hour, or bhp-hr NOx emissions, and .01 g/bhp-hr particulate matter. CARB also makes optional low NOx standards of 50 percent, 75 percent and 90 percent lower than 0.2 g/bhp-hr available.
CARB wants to reduce acceptable NOx levels to .02 g/bhp-hr.
Lower NOx emissions can be achieved by addressing cold start emissions and emissions during low speed, low load operations – circumstances that urea-selective catalytic reduction systems currently are ineffective treating. A combination of after-treatment technologies integrating engine control strategies with “advanced catalysts and after treatment system controls,” such as exhaust gas thermal management, ammonia generator, electrically heated catalyst, fuel burners, exhaust gas recirculation and other technologies are undergoing testing.
The use of Exhaust Gas Recirculation, or EGR, may raise eyebrows. CARB and the U.S. Environmental Protection Agency rejected Navistar’s attempts to use a proprietary EGR system for its trucks to meet 2010 emissions standards.
Navistar’s gamble on EGR ultimately cost the company its CEO, a board of directors shakeup, and potentially hundreds of millions in fines.
Natural gas engines for heavy-duty trucks are expected to meet lower NOx standards sooner than diesel engines, the assessment says.
CARB estimated that urea-SCR systems added to 2007 model year engines cost $3,000 to $4,500. Meeting .02 g/bhp-hr would cost an additional $500 per truck, the assessment predicts.
CARB encouraged interested parties to submit comments on the draft assessment within 30 days. Comments can be submitted here.
For California to meet 2023 and 2032 ambient ozone air quality standards, CARB staff estimate it will require a 90 percent reduction in NOx emissions below 2010 baseline levels measured in the South Coast air basin. Meeting a newly proposed federal ozone standard will “be even more challenging,” the assessment said.
The report said truck sales in 2014 were up 17.6 percent compared to 2013 figures, with Freightliner leading market share at 31 percent. Second was International at 14 percent. Cummins led the engine manufacturing market with 47 percent.
Lower NOx requirements aren’t likely to be limited to California. CARB staff recommended that the agency petition the U.S. Environmental Protection Agency to require that the lower NOx standards be applied to all trucks nationally.
“Because trucking emissions are such a significant source of GHG and criteria pollutant emissions, achieving reductions within the trucking sector is a key component in the strategy to meet California’s climate and air quality goals,” CARB said.
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