We're just about a year away from the next EPA emissions standard and fleet owners are faced with a familiar challenge: competing technologies, conflicting claims and a war of words that can only get ...
We’re just about a year away from the next EPA emissions standard and fleet owners are faced with a familiar challenge: competing technologies, conflicting claims and a war of words that can only get hotter.
What to do?
First, let’s quickly get familiar with the basics. Then let’s isolate the main claims being made, and finally determine the questions that need asking.
EPA’s 2010 emissions standard will reduce NOx (nitrogen oxides) down to 0.2 g/bhp-hr. There are two major approaches to achieve this. One is through an exhaust aftertreatment process called Selective Catalytic Reduction (SCR).These systems, commonly employed in Europe, consist of a catalyst, a separate tank which houses urea and the associated plumbing. A small amount of urea is introduced into the exhaust stream, causing a chemical reaction that breaks NOx down into harmless water and nitrogen. One highly touted benefit of SCR is the ability to reduce fuel consumption by about 3-5%. Cummins said the business case for delivering fuel economy performance simply proved too compelling to overlook when it dropped a shocker this August with its decision to join Volvo, Mack, Detroit Diesel and Paccar on the SCR front after initially supporting Exhaust Gas Recirculation (EGR).
That’s everybody except for Caterpillar, which also shocked the market this summer by announcing it would no longer supply heavy-duty on-highway engines for North America in 2010, and Navistar (parent company of International Truck and Engine). Navistar does not like SCR for a variety of reasons, and has instead focused on becoming EPA 2010-compliant by simply employing higher levels of EGR. The fuel in the new engine will be injected in five stages, which reduces the explosive effect of combustion and allows for a more efficient burn, creating less NOx in the first place, according to Navistar. The company is developing a high-pressure common rail fuel system that will boost pressures above 30,000 psi. As well, Navistar says its compacted-graphite iron engine block will allow it to withstand the higher firing pressures created.
The conflicting claims being made by the two camps are difficult to substantiate, even with an engineering degree. For example, Volvo has questioned whether an EGR solution will be able to achieve passive Diesel Particulate Filter (DPF) regenerations, pointing out that NOx plays an important role in facilitating passive DPF regens and having to actively regenerate the DPF would consume about 2.5 litres of diesel. With SCR, on the other hand, engine manufacturers can produce as much NOx as necessary within the cylinder, take advantage of its chemical properties to conduct an efficient passive DPF regeneration and then eliminate the NOx downstream in the SCR catalyst.
No so, counters Navistar, which insists its engines will continue to achieve passive regenerations. It points out that the common rail fuel system will produce less NOx than today’s engines in the first place and so the regeneration process should not be impacted.
Navistar, although not disputing the fuel-saving potential of SCR, questions the overall savings because what’s saved by burning less fuel may be offset by the cost of urea and the added complexity of urea systems.
That’s the technological capabilities, claims and concerns of engine manufacturers in a nutshell. Now some questions I think remain to be fully answered:
1. For SCR folks: Are concerns about urea valid? Urea will be consumed at an approximately 2% or 3% urea to diesel ratio, so for every 100 gallons of diesel burned, a truck will require three gallons of urea.
Concerns about urea pricing (expected to be below diesel pricing) and widespread availability of urea come 2010 (shortages would cause price spikes) must be addressed. Also, EPA requires that engines using SCR be downgraded if the urea tank runs dry, meaning the driver will have to monitor tank levels and replace the fluid when required. Are fleets ready and willing to involve their drivers in this manner?
2. For the “mature EGR” folks: Navistar will be using “credits”to be EPA 2010-compliant with its engine. Engine manufacturers in the US have earned credits for surpassing previous emissions standards, and Navistar acknowledges it will be cashing in some of those credits in 2010 to bring its engine into compliance.Will fleets, particularly those interested in appealing to shippers with the strictest environmental standards, be satisfied with that? And what fuel savings, if any, will Navistar’s engine provide?
3.For both:What will be the additional cost to the buyer for 2010 and are either of these technology platforms robust enough to take their respective supporters to the next emissions standards after 2010 or is yet another technological change on the way? MT
“There is a new four letter ‘f’ word in the trucking industry. It is called fuel.”
– Dan Goodwill, president, Dan Goodwill & Associates