LAS VEGAS — When the topic of 2010 emission solutions was still in its infancy, selective catalytic reduction (SCR) seemed to be a pretty good bet to win the approval of the EPA and most truckmakers for meeting the stringent environmental standards. Now … well, not so much.

Part of the reason SCR was highly touted for Class 8 highway applications early on was because it is cost effective and a proven technology. In fact, Europe has for years employed SCR to battle NOx for its own truck emission regulations.

Not surprisingly, then, it’s the two European-based OEMs — Volvo and DaimlerChrysler-Freightliner –that have declared SCR the solution of choice for 2010 North American heavy-duty engines.

International said months
ago it will not go with SCR for 2010.

Other engine makers were once expected to follow suit, but that hasn’t happened. International and Cummins (the latter will use SCR in medium-duty, at least in the short term) announced they will go with an evolution of existing cooled exhaust gas recirculation (EGR) technology and diesel particulate filter (DPF) for on-highway trucks.

They believe the EPA standards can be achieved by in-cylinder means, through an advanced fuel system, air management, combustion and controls. Nor, it is claimed, will they need any other form of NOx aftertreatment.

Critics of SCR are scared off by its requirement for urea, which is a
Nitrogen-based reducing agent that, when injected into the exhaust gas upstream of the catalyst, eliminates NOx by 90 percent. The main concern is that North America will never be able to establish a mature delivery infrastructure in time for the 2010 vehicles.

When asked about the future of SCR by TodaysTrucking.com at this week’s Heavy Duty Dialogue in Las Vegas, International Truck & Engine President Dee Kapur answered pointedly: “We don’t like it.”

Kapur pointed out that SCR needs vast continental infrastructure to replenish urea tanks. The liquid is known to gel up in cold climates and evaporate when heated — not exactly ideal in North America where temperatures range from -40 to over +40 Celsius. Tanks therefore would need to be fitted with automatic heating and cooling solutions.

Also, the issue of enforcement for urea compliance is a big question. Kapur says even in Europe officials have had a tough time ensuring urea tanks are topped up when they’re supposed to be.

Critics of SCR worry that enforcement of urea tank
compliance will be unenforceable in North America.

According to New York transportation market analysts at Bear Stearns, a consultant who specializes in designing and developing urea dispensing systems told the firm that while he’s pleased with how the European-based OEMs are helping truckstops build the urea infrastructure, he too is concerned that there is “still much work that needs to be done in a fairly short amount of time.”

He said the urea delivery system needs to be a joint effort by truck dealerships, the fuel distribution network, and the chemical distribution network; but at the heart of the problem is cost and the question of who will ultimately be responsible for bearing the brunt of the for the getting urea to the dispensing locations.

When asked which technology he thought would likely win the day — SCR or EGR — the Bear Stearns source said he thinks that for the most part the long-haul market will stay with EGR, while in certain operations in cities and various vocational settings, SCR could be in demand as the needs of those markets are addressed.

Cummins, he notes, is a good example, as the engine maker is offering two solutions for different markets.

Kapur acknowledges that in the short-term there will likely be a two-tired market. But over time, the availability and portability problems of urea will be too daunting.

Furthermore, Kapur points out that a byproduct of ammonia when extracted from urea is carbon dioxide, which will undoubtedly be the next so-called pollutant truck manufacturers will be mandated to eliminate from exhaust pipes sometime over the next decade.

“There may be some applications for SCR, but if so, we think it’s a stop-gap solution, and it will be marooned in the future,” he says. “After 2012 or 2014, it’s done. After that, who’s going buy (those) vehicles?”