SAN ANTONIO, Tex. - Most engine manufacturers have successfully met the 2002 EPA emission standards, but as those trucks continue to be broken in, there are still other hurdles that loom ahead.Dr. Tom...
SAN ANTONIO, Tex. – Most engine manufacturers have successfully met the 2002 EPA emission standards, but as those trucks continue to be broken in, there are still other hurdles that loom ahead.
Dr. Tom Ryan, institute engineer with the Southwest Research Institute (SRI) in San Antonio, addressed a crowd of fleet managers at the American Trucking Associations’ annual conference about what they can expect in 2007, 2010 and beyond.
He prefaced his presentation by stating much of what he was going to say was strictly his own opinion. However, Ryan’s opinion is based on extensive research with diesel engines, both pre- and post-’02 emission engines.
SRI is currently testing seven ’02-compliant engines against each other to determine which ones deliver the best fuel mileage. While Ryan wouldn’t give out the results (that information can be purchased from the institute) he did say the difference between engines was considerable. Ryan also said testing has shown a significant difference in the amount of soot buildup in the various engines.
And he had plenty to say about what’s next for the trucking industry…
In 2007, low-sulfur fuel will be the norm, which should in itself help reduce emissions. In fact, legislation requiring diesel fuel to be no more than 15 PPM (parts per million) of sulfur will be passed in June of 2006, but Ryan thinks low-sulfur diesel will be phased in prior to that date.
“The refiners want to get the return on investment as soon as possible,” he said, noting they’ve invested a lot of money into achieving this new target and the sooner they begin selling it, the better.
As with most new developments, expect to pay a premium when the new diesel is available, warned Ryan. He said the EPA has estimated low-sulfur diesel will cost an extra four to five cents per gallon, however, fuel providers have denied this will be the case.
Low-sulfur fuel does present some new concerns.
“Reducing sulfur typically reduces the lubricating quality of the diesel fuel,” said Ryan, noting additional lubes may be necessary.
He added “You do have to be careful in terms of misfueling these vehicles, as there are issues associated with incorrect fueling.”
It’s not yet clear how well older engines will function on low-sulfur fuel, and vice-versa.
The EPA has also predicted the cost of engines in 2007 will increase by another US$1,200 to US$1,900.
The target for Particulate Matter (PM) for 2007 is .01 g/hp-hr. In order to achieve that, Ryan said he expects each engine will require a Diesel Particulate Trap (DPT). But there are a number of options worth exploring when trying to reduce NOx, each with its own challenges that must be overcome. They include:
Retarded injection timing: This option isn’t likely to be pursued as there is generally a one per cent loss in fuel economy for every five per cent reduction in NOx.
Exhaust Gas Recirculation (EGR): Lower consumption temperatures mean more PM, but use of a DPT could help offset that. This option would result in a zero to slight fuel consumption penalty, depending on the configuration of the EGR system.
Lean NOx catalysts: Ryan said the technology is inefficient and “I don’t think this technology is going to come along fast enough to play a role in 2007.”
Lean NOx Trap (LNT): Diesel engines with this option would have to be run quite rich – about 15 parts of air for one part of fuel. Today’s diesel engines typically run very lean.
Selective Catalytic Reduction (SCR): Challenges include having to add ammonia (urea) to the exhaust stream, which necessitates a separate tank. Access to urea also make this impractical for now, Ryan said.
The options for PM control in 2007 include the following:
Diesel Particulate Filter (DPT): These trap PMs and then burn them off. Soot burns off at a temperature of about 650 C. There will be some maintenance required. “These aren’t going to run a million miles,” said Ryan.
Diesel Oxidation Catalyst: Not a likely option when compared to DPTs, Ryan said.
The favoured route for combating emissions in 2007 will be Massive EGR with a particulate filter, according to Ryan. This will involve high EGR, high boost with the EGR taken downstream of the DPT. This option shouldn’t hinder durability of the vehicle. A DPT weighs between 40 and 60 lbs.
In 2010, emissions must be reduced by 90 per cent of today’s levels, so the industry can once again expect a substantial change – and a substantial cost increase. Ryan said 2010 engines may cost up to US$18,000 more than they do today.
The big battle in 2010 will be SCR vs. LNT. Both options increase displacement by 4-7x, so “either way you end up with more components.”
Ryan said SCR is heavily-favoured as the technology of choice in Europe for emissions control.
However, he’s not so sure it’s the best option. Both SCR and LNT have their challenges.
He said SCR has issues including: cost and complexity; urea infrastructure; extra tank and plumbing required; exhaust temperature control; doesn’t work well at low engine temps; urea handling; fuel consumption expected to be worse than today; extra cost of urea which is about half the cost of diesel.
LNT challenges include: EGR system cost; de-sulfation strategies; durability on 15 PPM fuel; exhaust temperature control; LNT system cost and complexity; regeneration strategies; and performance at low temperatures.
That said, Ryan predicted “LNT is a likely 2010 strategy for most manufacturers. The SCR issues are not likely to be resolved by then.”
Other changes may include things such as multiple turbochargers on some engines, new lubricants and in some cases there may be up to five injections per cycle.
While the 2010 diesel emissions standards will be comparable to gasoline levels, Ryan doesn’t expect the EPA to stop there.
“It’s likely that we’re going to see standards beyond 2010 for heavy-duty engines,” he said.
“The EPA will actively promulgate lower emissions standards for diesel engines. In 2010, they could announce another heavy-duty standard for implementation by 2014.”
He expects that in the post-2010 world, any additional standards will be fuel-neutral but they will be increasingly expensive as they utilize more advanced fuel injection systems.
Also, with more and more components being added under the hood, the weight of the vehicles is inevitably going to increase.
“The emissions standards will be met…I’m not sure we can do that cost-effectively. That’s going to be the issue,” said Ryan.