Clean-diesel retrofit lessons winning more audiences

Diesel Fuel News, March 18, 2002 by Jack Peckham

More U.S. fleets are finally starting to hear the voice of experience on clean-diesel retrofit technologies -- and learning that this option is far cheaper than "alternative fuels" solutions.

Example: New Hampshire-based transportation management consultant Heaney, Edelstein is taking its real-world experience with ultra-low sulfur diesel (ULSD) and diesel particulate filter (DPF) retrofits gained at Boston's Massachusetts Bay Transit Authority (MBTA) to show more public and private fleets how they can do likewise.

A recent Heaney, Edeistein seminar for a variety of fleet operators (transit buses, trash trucks, school buses, highway department heavy vehicles) at New Hampshire Department of Transportation gave managers first-hand accounts about what's involved with clean-diesel retrofits, what technologies are available, and what new systems are about to become available over the next year or two.

The message: Clean-diesel can achieve "CNG-like" emissions by combining ULSD with suitable engines and exhaust aftertreatment, such as catalyzed DPFs.

Low-pressure exhaust gas recirculation (EGR) and selective catalytic reduction (SCR) are in development now -- and demonstrations are sought, as spokesman Steve Edelstein says.

The STT long-loop EGR system can deliver upward of 50% NOx reduction, Edelstein showed at the recent seminar, and integrated with a DPF gives combined PM/NOx control (see Diesel Fuel News 2/4/02, p9).

Meantime, testing and engine mapping are underway for this application on several DDC, Cummins and Navistar engines, and plans are in the works to obtain U.S. EPA retrofit program verification, Edelstein says. The system should be "commercially available soon" and "pilot projects are needed," he told fleets.

Meantime, the Johnson-Matthey "SCRT" system combining SCR with a DPF is moving into pilot demonstrations in the U.S., including a project in Houston. Another project in the Northeast states with truck maker Mack uses the Siemens SCR system, he said. At least five of eight heavy-duty Class 8 trucks will combine SCR with DPFs or oxidation catalysts in test projects, he said.

At the same time, ULSD is becoming more widely available in the U.S. (see Diesel Fuel News 2/4/02, PL; 2/19/200], p1), typically with a 30 ppm sulfur cap in the Northeast, and lubricity levels are being maintained, he said.

DPF installations are becoming "smarter" thanks to experience at a growing number of fleets, and high-tech advances. Sophisticated electronic diagnostic modules mounted on-board vehicles can provide fleets with up to two months of key operating data.

Smart planning also can combine the matching of a DPF during repower of a vehicle with an appropriate engine, as in the MBTA experience, he said. For these installations, MBTA matched a DDC "reliabuilt" rebuilt Series 50 engine with a DPF during installation, Edelstein tells fleet managers.

Insulation around turbo pipe can help solve minimum-temperature issues to ensure regular DPF regeneration, he explains.