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THE ABCS of DEF
by Marco Beghetto
Engine makers must virtually eliminate particulate matter (PM) and nitrogen oxide (NOx) emissions from diesel engines as of next January. Time's almost up. All engine manufacturers with the exception of Navistar will use selective catalytic reduction (SCR) exhaust aftertreatment to meet the ‘010 standard, combined with a milder form of exhaust gas recirculation (EGR). SCR is the most common emissions solution in Europe, and 500,000 trucks now use it. Their regs aren't as rigorous as ours, so things aren't exactly the same. What's common on either side of the Atlantic is an SCR engine's need for DEF, or diesel exhaust fluid. It's often referred to as urea, but while that's indeed a key component, DEF is actually a 32.5% solution of chemically pure urea in deionized water. It reacts with smog-forming NOx in an SCR catalyst, turning that NOx into safe nitrogen and water. Drivers of 2010 International trucks equipped with the company's own Maxxforce engines won't need to deal with DEF, because they'll just use an advanced version of EGR. Cummins ISX engines won't be available in next year's Internationals, by the way, because the Indiana engine-maker decided last year to switch gears and opt for SCR instead of EGR. So at the start of 2010 the biggest engine you'll be able to get in an International truck is the 13-liter Maxxforce 13. But never fear, the company is about to announce the Maxxforce 15, and you'll be surprised to know that it's actually going to be a Caterpillar C15 made under licence by Navistar – a much reworked C15, with the troublesome ACERT technology replaced by a more or less straightforward EGR system. The engine won't be ready for sale until some time in 2011 if not later. Caterpillar, you'll remember, announced last year that it was getting out of the onhighway truck engine business altogether. It stopped production last month. Warring Words So on one side of the emissions fence we have Navistar, and on the other we've got Cummins, Detroit Diesel, Mack, PACCAR, and Volvo amongst the heavyduty engine makers. This is not a peaceful barnyard. Navistar says that EGR is a proven system that requires no aftertreatment and thus no DEF. That means no extra tank to hold the fluid, no dependence on you drivers to routinely fill it up, and a lighter truck by about 300 lb. Company spokesmen have also been very vocal about DEF, claiming it's toxic and volatile and bound to be expensive. The opposition calls that "misinformation". Among the DEF "myths" that Detroit Diesel sought to counter at a recent press conference is that notion about DEF's toxicity. In fact, they said, it's not toxic at any temperature. And while it will freeze at something like 11 degrees F, Detroit says small immersion heaters in DEF tanks will prevent that. Nor will DEF be as expensive as some have claimed (like US$19.05 per gallon). In fact, DEF can be had for as little as US$2.50 a gallon in bulk. Supporters point out that SCR technology is the first since 2002 to reduce emissions while at the same time providing up to 5% in fuel savings compared to their previous EGR engines. Nor will their 2010 offerings require anywhere near as many DPF regenerations DEF will be injected into the system at the rate of two or three gal for every 100 gal of diesel, out of on-board tanks ranging from six to 23 gallons, depending on the application. Dave Siler, marketing chief at Detroit Diesel, says heavy Freightliner and Western Star trucks with 2010 Detroit engines will have 23-gal DEF tanks, good for 5000 to 7000 miles between fills. There's no real likelihood of fitting larger tanks. It seems about as burdensome as topping up windshield-washer fluid. And while packaging constraints can exist on some complicated vehicle layouts, truckmakers seem able to use chassis real estate and a variety of DEF tank shapes to solve most space issues. Things can get a little hairy with exotic trucks like twin-steers and such. Def Distribution Today, it seems only Navistar is expressing doubts that the supply and sales infrastructure for DEF might not be ready to meet 2010 demands. Pilot Travel Centers and Travelcenters of America are two truckstop chains leading the way in over-the-road retail. The latter chain is committed to equipping every one of its locations with DEF pumps, while Pilot will start off with dispensers at about 100 sites. Most truckstops will at least offer pre-packaged or top-off containers. In Canada some folks think the lack of a vast truckstop network and dependence on unmanned cardlocks could lead to isolated DEF shortages for some rural truckers a little too far north of the 49th parallel. David McKenna isn't particularly concerned, though. As a former Torontonian, the powertrain marketing manager for Mack Trucks says he spends a lot of time thinking what the impacts might be in Canada. "Weather, weights, distances and isolated areas always spring to mind," he says. "What I see unfolding as EPA 2010 chassis hit the road, is that DEF is scalable, meaning that depending on the location and amount of DEF consumed, there will be a right-sized dispenser and system available." McKenna and Siler both confirm that truck dealers here will sell DEF as stock material, including an abundance of 2.5-gal ‘tote' jugs, which alone can carry a truck 800 miles. There's more to know about DEF, so we'll continue this next month.
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