EDMONTON, (Aug. 8, 2005) — As part of its ongoing interest in exploring ways to reduce vehicle emissions in urban areas, the Clean Air Strategic Alliance has just completed a comprehensive pilot project on the effectiveness of diesel particulate filters in chilly Edmonton.

CASA — a non-profit association composed of government, industry, and environmental groups — conducted a one-year test of the filter on two diesel buses in Edmonton Transit System’s fleet between January 2003 and January 2004.

The objectives of the Diesel Particulate Filter Project were to: Demonstrate effectiveness of diesel engine emission reduction technology in an Alberta; Provide an opportunity for Alberta’s transportation and transit industries to acquire hands-on experience with the installation, use and performance characteristics of CRT technology; Stimulate the transportation industry’s interest in and adoption of air pollution reduction devices; and improve urban air quality.

The project’s main conclusion was that the DPF — specifically the Johnson Matthey Continuously Regenerating Technology — worked in Alberta’s climate. Although DPF technology is being used in a number of jurisdictions throughout North America and the world, there is little practical experience with cold weather applications of this technology, says CASA.

The results showed specifically that there were major reductions in emissions of three main pollutants, but no significant change in the emission rate of nitrogen oxides: Total hydrocarbons reductions of 51-87 percent; Carbon monoxide reductions of 67-89 percent; and total particulate matter reductions of 60-75 percent.

Before beginning actual emissions testing of the project, the equipment was subjected to dry runs to ensure it was operating as it should. A route was chosen to simulate the normal operating conditions for a typical city bus, including numerous stops and starts, travel at various speeds, and idling periods.

Operationally, the filters require ultra low sulphur diesel fuel (ULSD), which is mandated at 15 ppm for all diesel engines next year — and are applicable in modern engines with high combustion temperatures. By using diesel particulate filters, it is possible to advance emissions reductions that would otherwise take longer to occur through fleet turnover. The filters work mainly by converting CO and HC into carbon dioxide and water and then trapping soot on the walls of the filter, where it is destroyed.

“The test was very useful to ETS in evaluating the performance of the DPF technology and gaining experience with installing and maintaining the device,” the report stated. “The filter did not impair bus performance, in terms of fuel economy and driving performance, but it does require annual cleaning to ensure proper continued operation; the cleaning process will add about three hours to the annual maintenance inspection for each bus.”