London-based Johnson Matthey Technology has launched a demonstration of its advanced diesel retrofit technology with a fleet of 16 older trucks owned by the Ralph's supermarket chain in southern California.

Johnson Matthey and its partner, Cummins Emissions Solutions, retrofitted 16 older Class 8 grocery trucks used in the Ralphs' delivery fleet with the new SCRT four-way control system. The trucks range in age from 1998 to 2004.

The demonstration program involved a local partnership between Ralphs, the South Coast AQMD and Johnson Matthey. Johnson Matthey will collect data on the vehicle's emissions performance by measuring back pressure, temperature and nitrogen oxides (NOx), a key smog-forming pollutant.

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 percent) with a selective catalytic reduction (SCR) catalyst that reduces NOx by some 60 to 80 percent. 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 Ralphs trucks with this system could potentially remain in compliance with existing and proposed air quality regulations until 2020.

In a previous test using a similar fleet of grocery trucks in the Sacramento area, Johnson Matthey found that the SCRT system reduced NOx by an average of 84 percent compared to pre-retrofit levels. Those trucks had 2005 Cummins, 400-horsepower ISM engines with an EGR (exhaust gas recirculation) system.