My blog about Cummins’ flip-flop on using selective catalytic reduction (SCR) and urea in its 2010 heavy-duty diesels has spurred some interesting comments about urea, the mysterious blue liquid that will soon become as much a part of the heavy trucking industry as EGR and DPF have. A few of those concerns I can comment on here, but a few will have to remain open questions until we have some real-world experience with urea.

Going back to the conference call in which Cummins announced its new product plans, there were a lot of questions about urea, and a lot of tacit admissions that using urea in heavy trucks may not be a walk in the park. Back when Cummins had previously announced that it would only use an SCR/urea system in its medium-duty product, company executives explained that the system was well-suited to the medium-duty market because those vehicles traditionally returned to home base after completing their duty cycle, and therefore it would be easy for fleets to maintain urea levels in the trucks. Heavy-duty engines, not so much, according to Cummins execs.

Of course, with Cummins’ new plans that argument has gone up in a puff of smoke, so to speak, and so those same execs, two weeks ago, were suddenly being asked to address certain sticky questions about urea. One was about the rising cost of urea, which, one reporter claimed, could cost just as much as diesel fuel by the time 2010 rolls around. Cummins’ reply was that even if urea does cost that much, “there are cost benefits” in the form of a potential five percent improvement in fuel economy. Another question concerned the frequency with which urea tanks would need to be refilled, to which Cummins responded that a two- to three-week interval would be “typical” for a Class-8 truck. Ok, that may be a reasonable time frame, but if the urea refilling doesn’t sync with filling the fuel tanks, how many mistakes are going to be made?

Now, I want this urea system to work, because… well, because it has to. But there are a lot of questions, and, in truth, none of the answers that engine OEM execs have been coming up with are completely reassuring to me, and I doubt that they will be to most fleet maintenance managers. Do they reassure you?

Do you buy Cummins’ engines in your heavy-duty vehicles? Were you counting on avoiding the whole SCR/urea issue in 2010 buy spec’ing Cummins ISX engines with enhanced EGR? Hate to break it to you, but you’re going to have to rethink your plans.

Yesterday Cummins announced that it is changing its strategy for meeting the Environmental Protection Agency (EPA) 2010 diesel emissions requirements for lower NOx levels. The company had previously announced that it would meet the 2010 standards for its medium-duty engines using selective catalytic reduction (SCR) and urea, while its heavy-duty engines would rely solely on enhanced EGR and therefore avoid the use of SCR and liquid urea, which many consider cumbersome and inconvenient.

The beauty of Cummins’ original plan, of course, was that users would not have to refill a urea tank on their trucks, something the company was not shy about promoting. But yesterday that all changed. The company announced that, due to rising fuel prices and technological advances in the construction of SCR aftertreatment devices, it will now equip its 11.9 and 15 liter ISX engines for 2010 with SCR devices. That means that any truck with one of these engines will have to have a urea tank, and the drivers of those vehicles will have to fill those urea tanks regularly, or risk damaging their trucks and being in violation of the law.

What made the difference? Well, the Cummins folks explained that new materials being used to make SCR devices have made it possible to switch to this technology and actually save fuel. Seems that $4 a gallon really has been the tipping point…

Since every other engine maker is already planning to use SCR and urea, it simply means that Cummins is joining the crowd, and there’s no harm in that. Of course, you lose an option, and that’s never good. And, if you were planning your 2010 purchases based on Cummins’ previous plans, you might not be too happy about that.