Conventional wisdom holds that newer is better -- or in the case of vehicles -- cleaner, but that adage is being challenged by new diesel exhaust technology that can make older big-rig trucks cleaner than even the most modern clean diesel trucks.
Johnson Matthey's latest diesel emissions technology, the SCRT system, has demonstrated in a trial, using a fleet of 16 older trucks owned by a Northern California grocery store chain, that it is possible to create a new adage: older can be cleaner.
Results were released today of a demonstration using a number of older Class 8 grocery trucks retrofitted with Johnson Matthey's new SCRT four-way control system. Working with partner Cummins Emissions Solutions, the Johnson Matthey emissions system was tested for more than 1,000 hours as the trucks traveled throughout Northern California hauling grocery products to Raley's family of grocery stores.
The demonstration program involved a local partnership between Raley's, the Sacramento Metropolitan Air Quality Management District (SMAQMD), and the Sacramento Emergency Clean Air and Transportation program (SECAT).
The 4-way SCRT exhaust emission control system combines Johnson Matthey's patented two-stage CRT particulate filter system (to reduce particulate matter by more than 85%) with a selective catalytic reduction (SCR) catalyst that reduces oxides of nitrogen (NOx) between 60 - 80%, a key smog-forming pollutant. It also reduces carbon monoxide (CO) and hydrocarbons (HC) by more than 90 percent. The result is a four-year-old truck with NOx emissions lower than those of a brand-new 2008 truck.
The findings of the 1,000-hour test were that the SCRT system reduced NOx in Raley's trucks by an average of 84 percent compared to pre-retrofit levels. The trucks involved had 2004 Cummins, 400-horsepower ISM engines with an EGR (exhaust gas recirculation) system. The ISM is a commonly used engine in Class 8 trucks hauling heavy loads.
"Johnson Matthey is extremely pleased with the real world results that the SCRT system has shown," said Marty Lassen, Johnson Matthey's Director of Commercial Development and Marketing. "This will literally give a new lease on life to many older trucks that are capable of providing ongoing service, but in stock form cannot meet new ARB private fleet emissions standards. This will provide California and the rest of the nation another tool to help meet clean air goals."
The next stage for this technology is verification by the California Air Resources Board and the U.S. Environmental Protection Agency, which is underway now that the 1,000 hours of real-world use has been completed. Johnson Matthey has nearly 50 demonstration units running in California and Texas. After thousands of hours of operation, the SCRT system retrofits on both EGR and non-EGR engines has reduced NOx emissions by as much as 84%.