Low-NOx rebuilds fall short; SCR test programs moving

Diesel Fuel News, July 21, 2003 by Jack Peckham

The seven diesel engine makers that signed consent decrees with U.S. EPA to reprogram "defeat devices" that increased nitrogen oxides (NOx) on certain 1990's-era engines now report rather slow "fix rates" for supplying low-NOx reprogramming kits.

Here's what EPA shows for low-NOx kits supplied, by engine maker:

Company        Number of         Affected
               kits supplied     engines

Caterpillar    29,823 installed  288,967

Cummins        5787 installed    351,387

DDC            12,846 installed  294,445

Mack           927 installed     60,506

International  384 installed     37,201

Volvo          49 installed      9,707

Renault        Included in       (claimed
               Mack's numbers    confi-
                                 dentiality)

So, while Cat seems to have fixed over 10% of its allegedly non-complying engines, the industry-wide "fix rate" is about 4.8%, the report indicates.

EPA concedes these low-NOx "fix rates" are lower than it expected. But in response to a question at a "consent decree" review hearing last week, the agency said it hasn't yet developed new modeling or revised estimates of emissions reductions.

Other highlights from last week's EPA review of emissions mitigation projects:

-- Volvo now has 23 trucks fitted with selective catalytic reduction (SCR) systems, and is about to complete the fitment of diesel particulate filters (DPFs) in combination. All the trucks are running on ultra-low sulfur diesel (ULSD).

-- Mack reports that all 10 of its SCR-equipped test trucks have been running in real-world service since mid-2002, eight at UPS and two at New York Dept. of Sanitation.

Meantime, another 35 Mack trucks are being fitted with DPFs, following tests on six trucks with "mixed success," Mack says. Two of the six DPFs failed when they were installed on trucks using regular diesel fuel (not ULSD), so next test may switch to exclusive ULSD.

-- Cummins reports it will retrofit 260 New York City garbage trucks, 300 Washington, DC, transit buses, 45 Sacramento and 30 Los Angeles school buses, and 40 King County (Wash.) transit buses with DPFs, plus help pay for ULSD in King County.

-- DDC has installed combined DPF/SCR systems on three class-8 line-haul trucks, for real-world fleet testing. One truck is running about 5,000 miles/week.

-- Cat is setting up an evaluation project to demonstrate SCR, DPF, and NOx adsorber technologies, plus combustion technology development.