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Prospects for Light-Duty Diesels in the US

On paper, clean advanced technology diesel passenger cars and light-duty trucks should be charging into the US market. The changeover to Ultra Low Sulfur Diesel that takes affect this year—a profound change akin to the removal of lead from gasoline, according to the EPA—opens the door to advanced emissions aftertreatment controls that can meet tough US emissions regulations.

The torque and power of diesels should appeal to US drivers, and the increased fuel economy of diesels compared to current gasoline counterparts should appeal to drivers as well.

But while acknowledging all of the above and stating that they are planning diesel introductions into the US market, a panel at DEER 2006 comprising GM, DaimlerChrysler, BMW, Honda, Volkswagen the EPA and the Martec Group also noted some major hurdles to a rapid proliferation of diesel models in the US.

A common worry shared by the automakers is that the costs associated with overcoming some of the issues will further increase the price of diesels, reducing the economic incentive for buyers. Should the price of oil collapse, they worry about the potential for a repeat of the diesel boom and bust of the 1980s.

The technical hurdles can be grouped into two basic categories which are inter-related:

  • Emissions compliance, specifically the NOx limits; and
  • Fuel quality.

Emissions. The US Tier 2 regulations—which are converging with California LEV regulations—are the toughest in the world. A future Euro-5 diesel passenger car won’t qualify for Tier 2 Bin 5. Automakers are developing advanced combustion regimes with associated reductions in engine-out NOx and aftertreatment systems to hit the target.

On the NOx front, Lean NOx traps (LNT) and urea SCR systems are the leading approaches automakers are exploring. LNT has limitations in efficiency that make it less suited for larger vehicles and in durability, and urea SCR faces the fundamental issue of getting the EPA on board with its use, given potential issues with compliance. (How, in other words, do you ensure that drivers replenish the urea to ensure that the emissions aftertreatment system continues to work?)

Fuel quality. The variable range and threshold of some properties of US diesel fuel raises a number of issues for the automakers. For example, US diesel cetane numbers range from 38-58; European numbers range from 50-60. US aromatics can range from 13% to 50%.

The wide range and lower threshold of centane numbers drives a need for a variety of engine modifications, including more EGR, and more cold starting aids on the engine, according to Ford’s Brien Fulton in a separate presentation at DEER. High aromatics also increase engine deposits, EGR deposits and exhaust system deposits. These, and other factors, limit the synergies with European diesel powertrain technologies for the US.

The automakers. Of the automakers participating in the panel, GM was the least committal toward a product direction.

Diesel powertrains satisfy unique vehicle requirements in utility and large vehicles, but the economic payback diminishes as you go down in vehicle class...the proportion of the financial improvement diminishes, and it becomes more of a challenge to bear the cost of powertrain additions that go along with the diesel technology.

Not seeing a clear solution to meeting Tier 2 Bin 5 requirements, GM has been reluctant to introduce a vehicle.

In principle, if diesel is ever going to be widely accepted as a fuel solution in North America, it needs to be seen as comparable to its gasoline counterparts [in terms of emissions]. That ultimately is where we need to be. As long as there is a perception that diesel is an exception, it will never be widely accepted by the regulatory community or consumers.

—Michael Potter, Chief Engineer, Diesel Technology, GM Powertrain-Europe

DaimlerChrysler, which is outspoken about its BLUETEC technology framework as being the “Tier 2 Bin 5” enabler (earlier post), is nonetheless primarily relying on Bin 8-compliant introductions over the next year. A big consumer factor for DaimlerChrysler is the image of diesel.

For an expanded diesel market, the image has to be right. If we are going to go into the mainstream, we’re looking at regular sedans and SUVs...it’s very important to get the image right.

—Simon Godwin, DaimlerChrysler Manager for Regulatory Affairs

BMW is planning on diesels in both its sedans and SUVs for North America, and has sketched out a Tier 2 Bin 5 approach that relies on modified combustion, an advanced EGR system, an adapted fuel injection system, new control devices, additional sensors, OBD functions, a DPF and urea SCR system.

Wolfgang Mattes, BMW’s director of functional development, was particularly concerned about the problem of On-Board Diagnostics that meet US requirements.

We need some compromises to get diesel in [to the US market], such as the phase-in period for OBD.

—Wolfgang Mattes

Honda, given its recently announced strategic direction to use diesel powertrains for fuel-efficiency in its larger vehicles, was very bullish about its technical approach (earlier post) as well as on the potential benefits of diesel.

We want to contribute for clean diesel technology as we have for the gasoline engine.

—Yasuyuki Sando, Honda Senior Manager Advanced Powertrain

Volkswagen has been selling diesels in the US for more than 25 years. Diesels currently constitute about 15% of its US sales.

[Diesel] will succeed by delivering increased efficiency, reduced CO2 emissions, high levels of performance, and being the best platform for renewable fuels including biodiesel, sunfuel and sundiesel.

—Klaus-Peter Schindler, Volkswagen

Schindler noted that diesels will compete against and have to coexist with other technologies, including advances in gasoline engine technology, the success of hydrogen, and the potential public focus on long-term solutions, such as hydrogen.

Comments

Carl

"First of all, no one has the certain answers."

That's true (virtually all of the dissension is from CARB). There's also some dissension about anthropogenically-linked global climate change.

This is from a graduate-level environmental engineering course I completed:


"…The atomic oxygen produced by the photolysis of NO2 is very reactive and readily combines with O2 in the air to form O3. In the presence of NO, however, the O3 will immediately decompose, regenerating the nitrogen dioxide. This nitrogen dioxide photolytic cycle is summarized in the following three reactions.

NO2 + hv --> NO + O
O + O2 --> O3
O3 + NO --> NO2 + O2

Hence, while the presence of NO2 is required to form O3, the nitrogen dioxide photolytic cycle by itself does not generate net ozone, and cannot explain ozone accumulation….

...ROG [VOC] reductions (with constant NOx) always lead to a slowing of the ozone production process and lower peak ozone concentrations. NOx reductions (with constant ROG) can lead to a speeding up of the ozone process, and can increase or decrease peak ozone values depending on the ROG-to-NOx ratio.

Thus, whereas ROG control is never detrimental, NOx control can be detrimental, particularly in the central cores of urban areas...."

Source: Air Pollution Control, A Design Approach; Cooper, D. C.; Alley, F. C.; Third Edition, pages 595 and 600


From another graduate environmental engineering textbook, Air Pollution, It's Origin and Control; Wark, Warner, Davis (page 476):

[O3] = kI[NO2]/[NO] (I is the intensity of the sunlight; brackets [ ] represent "the concentration of")

so, if [NO2] = [NO] (i.e., NO and NO2 are in equilibrium), [NO2]/[NO] = 1 and [O3] = kI

Empirical data show that kI = ~25 micrograms/m3 or about 0.015 ppm (15 ppb), so if [NO2] = [NO], O3 = 15 ppb, far below the NAAQS one-hour standard of 124 ppb or 84 ppb eight-hour standard (about what would occur in natural background (pre-industrial) conditions).


I don't think this phenomenon is that unexpected or "weird".

Carl

"Did you see the word "TOWARDS" that I used?

Try again, please."

OK - you're NEVER going to even approach zero, roughly a third of NOx in non-anthropogenic.

Joseph Willemssen

Carl, we've had this debate before. Were you not satisfied with the first iteration of it? You're simply rehashing what you said then, and in addition, aren't really addressing anything I said except to resort to "appeal to authority" fallacies.

Within the pollutant level bands we currently live with, it is obviously possible that decreasing NOx can increase smog. The point I made then and still make is that once you move out of the band downwards, there will be a different dynamic. In either case, there's far from any consensus on this issue - not anything along the lines of climate change theory, so to assert some sort of equivalence is also inaccurate.

Accepting your worldview means that more emissions makes the air better, in general. That's ridiculous.

Joseph Willemssen

OK - you're NEVER going to even approach zero, roughly a third of NOx in non-anthropogenic.

I see. So smog is "natural". Then why isn't there smog everywhere? Did ancient humans live trapped in clouds of smog?

Let's be real here.

Carl

"Accepting your worldview means that more emissions makes the air better, in general. That's ridiculous."

Where did I say more emissions will make air quality better? I'm saying VOC/CO emissions need to be limited relatively more than NOx, exactly 180 degrees from what the current regs (Tier 2/LEV II) do.

Can you point to any sources other that the regulatory agencies that disagree with lower NOx emissions on weekend being the cause of higher ozone (smog) on weekends in urban areas?

I live/work about 45 miles downwind (statistically speaking) from a large urban area in the southeasten U.S. in which three busy interstates converge Based on my own studies, weekend ozone levels are no different from weekday levels. If what you say is correct, why aren't weekend ozone levels lower in this downwind rural area? Another aberration?

If I thought the current on-road emission regs would significantly improve air quality, I can assure you that I'd be all for them. But I really don't based on the empirical data provided by the weekend ozone effect studies.

Joseph Willemssen

Where did I say more emissions will make air quality better?

Um, the whole "weekend effect" notion states that lower emissions during the weekend create more pollution, ergo more emissions means better air quality. Again, possibly true within certain pollution level bands, but the general logic behind such thinking, extended rationally, creates a ridiculous conclusion.

Can you point to any sources other that the regulatory agencies that disagree with lower NOx emissions on weekend being the cause of higher ozone (smog) on weekends in urban areas?

Like I thought, you want a repeat of our last exchange on this. You have the links I gave you last time.

I live/work about 45 miles downwind (statistically speaking) from a large urban area in the southeasten U.S. in which three busy interstates converge Based on my own studies, weekend ozone levels are no different from weekday levels. If what you say is correct, why aren't weekend ozone levels lower in this downwind rural area? Another aberration?

Why are you dodging my question? You're the one asserting that a good chunk of NOx is "natural", therefore to try and reduce human output of it is not only pointless, it creates MORE pollution (apparently forever and ever, in your view). The point is that your view is essentially we shouldn't try to lower NOx levels. Indeed, they should be higher in some cases, for the sake of clean air.

If you can't see the fundamental flaws with that whole line of thinking (including the fact that smog is a modern phenomenon, even though you say much of NOx is "natural" so we shouldn't try to deal with it).

If I thought the current on-road emission regs would significantly improve air quality, I can assure you that I'd be all for them. But I really don't based on the empirical data provided by the weekend ozone effect studies.

Well, bully for you. Thankfully you're not in charge of decisions about such things.

Carl

"Um, the whole "weekend effect" notion states that lower emissions during the weekend create more pollution, ergo more emissions means better air quality."

No, the RELATIVE reductions on weekends is about 50% for NOx and about 15% for VOC/CO. This leads to about 50% higher ozone levels. The point of these studies is that we need to reduce VOC/CO relatively more/faster than NOx.

Actually, purely from a ozone perspective in urban locations, raising NOx WOULD reduce smog, but then problems with the NO2 NAAQS would become an issue.


"You're the one asserting that a good chunk of NOx is "natural","

It is. Lightning is a large source (lightning heats the column of air through which it passes to hotter than the surface of the sun). Some "natural" NOx (and ozone) comes from stratosphere intrusions into the troposphere cause by strong mid-latitude cyclones. The average concentration of ozone in the stratosphere is 15 ppm (15,000 ppb).


"The point is that your view is essentially we shouldn't try to lower NOx levels."

We need to decrease anthropogenic VOC/CO faster than we decrease anthropogenic NOx. I don't disagree that ZERO anthropogenic emissions should be the goal, but we need to be smart about how we approach doing that.


"Well, bully for you. Thankfully you're not in charge of decisions about such things."

I don't see why we can't have a civil discussion without resorting to condescension. Beside, how do you know I'm not?

Chingy

Joe, its time for your time-out. You are being nutty and living up to your status of local anti-diesel zealot. You're acting like the fool you so love to be. Like I tell my dog "knock it off". Oh, and if you think for a moment that your little alter-ego "George" was fooling anyone, you might want to at least try to modify your writing style and catch phrases.

See, people, Joe is a zealot. No matter how much common sense, data, and anecdotal evidence you throw his way, he ain't gonna change his mind. Soon enough he'll be some lonely old guy, locked up in his pathetic apartment, muttering about the children and their scarred lungs...while the rest of the world drives efficient diesels and DHEVs, burning domestic and carbon neutral fuel. Pity him.

Joseph Willemssen

I don't see why we can't have a civil discussion without resorting to condescension.

Carl, you started that process with the "appeal to authority" responses upthread. I also asked why you wanted to repeat a discussion we've already had. Are you changing your mind? Learning anything new? I'm not. I'm just seeing a discussion repeated almost verbatim.

Beside, how do you know I'm not?

I don't. But since you're complaining about it, then it is reasonable to assume you're not having influence in a way that you want.

When I see these "weekend effect" arguments I just scratch my head because the underlying logic is that less emissions is bad. If you feel CARB "isn't being smart about it", then it's probably best that you bring it up with them. Somehow I think they've thought about these things in depth and are well aware of the science and tradeoffs involved.

Joseph Willemssen

"ARB Report on the Ozone Weekend Effect in California - Executive Summary"

Chingy

Joe, hello? Your meds run out again? Like my dog, you just can't stop barking. If you were here in person, a little spritz of lemon juice in the snout would work wonders. Although you might very well need a full on shock collar. :)

george

Carl wrote: This nitrogen dioxide photolytic cycle is summarized in the following three reactions.

NO2 + hv --> NO + O
O + O2 --> O3
O3 + NO --> NO2 + O2

Hence, while the presence of NO2 is required to form O3, the nitrogen dioxide photolytic cycle by itself does not generate net ozone, and cannot explain ozone accumulation….

Carl, I question this analysis. The rate of the third reaction should be exceedingly low, because it is a second order process in two species (O3 & NO) that are present at very low concentrations. Unless the rate constant of the third reaction is many orders of magnitude greater than the second (which I think is improbable), the O3 concentration is going to have to go up. The reaction sequence may be OK thermodynamically, but kinetically it looks bogus. In other words, it looks to me like the book may have gotten it wrong. Is there something I'm missing here?

Later you say:
so, if [NO2] = [NO] (i.e., NO and NO2 are in equilibrium), [NO2]/[NO] = 1 and [O3] = kI

Why would we expect [NO2] = [NO] at equilibrium? The photodissociation is facile, but where are the equally rapid processes for the back reaction (NO -> NO2)? The most plausible pathway is via atomic oxygen, but it's not like there's a lot of .O. hanging around near ground level. The kI of 25 ug/m3 is probably OK, but [NO2]/[NO] is going to be very small; I just don't think this NOx eats ozone hypothesis holds water.

umm, Chingy, I'm not Joseph's little alter ego. I'm a whole 'nother guy. Your last couple of posts are starting to sound a little creepy, btw.

Chingy

Okee-dokee there "George" (with the multiple return email addresses). I guess I just fell off the turnip truck so I'll go along with your roll-play.

Joe, you do amuse me so! :D

Joseph Willemssen

That troll's a trip, isn't he, George?

I'm flattered that in his addled little mind he thinks I'm you. Last time I took chemistry was in high school, so what you were saying about the reactions is beyond what I could possibly write.

Drop the owner of this website an email and he'll get around to cleaning up the trolling.

Chingy

Joe, you're talking to yourself. As for referrals to the admin, you're right, I think I should bring the admins here up to speed on your antics on Treehugger.

Here's a great string where the admin admonishes you nicely:

http://www.treehugger.com/files/2006/03/epa_test_confir.php

In fact, a search of Treehugger shows a bizarre number of rapid-fire, rambling posts by you. It also shows you bullying and being generally unpleasant to anyone who disagrees with you.

I may be a bit abrasive, but so far I have not been shut down by an admin.

One common thread is that you generally are at your height of unpleasantness when it comes to diesel. Hence my labeling you our local anti-diesel zealot. Again, searching Treehugger and Greencarcongress shows this to be true.

Now, how exactly am I trolling?

Carl

Carl, I question this analysis. The rate of the third reaction should be exceedingly low, because it is a second order process in two species (O3 & NO) that are present at very low concentrations. Unless the rate constant of the third reaction is many orders of magnitude greater than the second (which I think is improbable), the O3 concentration is going to have to go up. The reaction sequence may be OK thermodynamically, but kinetically it looks bogus. In other words, it looks to me like the book may have gotten it wrong. Is there something I'm missing here?

George,

I suppose the book could be wrong. I copied verbatim from it (pages 595 and 600). I have a graduate degree in atmospheric chemistry (masters), but that was nearly 20 years ago, so my recollection of third order reaction rates is pretty fuzzy now.

However, that's not the only reference to the chemistry:


"…Near the earth's surface, small amounts of ozone are continuously created and destroyed in ongoing natural cycles. When nitrogen oxides (pollutants formed from the burning of fossil fuels), are added to the air more ozone is created, but then is quickly destroyed again. The balance of ozone creation and destruction shifts drastically, however, when hydrocarbons are added to the atmospheric mix.

Hydrocarbons --vapors from solvents, gasoline, dry cleaning fluids and hundreds of other common substances--actually add to the creation phase of the ozone cycle, while circumventing the destruction phase. Summer heat and the increase in sunlight intensity speed the rate of these chemical reactions, triggering rapid formation of ozone. This is why ozone "health advisories" often are issued during the summer, but never during the winter. …"
http://www.dec.state.ny.us/website/dar/bts/ozone/ozrpt.html


"…Simplified chemistry:

UV radiation (hv), acting on atmospheric NO2 creates ozone (O3):

NO2 + hv ---> NO + O

O + O2 ---> O3

But ozone is also destroyed (titrated) if NO is still present:

O3 + NO ---> NO2 + O2

Why does O3 build up? If volatile organic compounds (VOCs) are also present, NO is consumed by other reactions and is not available to titrate the O3: VOC + NO ---> NO2 + other products …"

http://www.nws.noaa.gov/ost/air_quality/Davidson.pdf


"…NO2 splits under the sunlight to produce NO + O. Then O reacts with O2 to produce O3. O3 reacts with NO to produce NO2 and O2. At the end of this reaction there is neither net gain nor loss for ozone. However, in the presence of hydrocarbons, HO2 and RO2 radicals are produced. These will convert NO to NO2, without losing ozone; thus, ozone concentrations will increase…."

http://www.baaqmd.gov/brd/advisecouncil/tec_min_060304.pdf (page 7)


The kI of 25 ug/m3 is probably OK, but [NO2]/[NO] is going to be very small; I just don't think this NOx eats ozone hypothesis holds water.

If [NO2]/[NO] is very small, then you'd have a lot of NO and very little NO2, right? A lot of NO would titrate the O3, right?

I'm an operational meteorologist involved in air quality forecasting, so if you have any insights, I'd appreciate hearing them.

Joseph Willemssen

Wow, someone's still hung up on the fact that they plagiarized something 6 months ago and was busted for it.

Seems like someone needs to move on.

George

Carl, I don't think that I have any great insights- smog is a pretty complex chemical problem. While I may question the NO2 pathway, the presence of NO in the original exhaust stream and any VOCs in the mix are confounding factors. The weekend effect appears to be real and we need to get a handle on the cause of it.

a lot of NO would titrate the O3, right?

Yes, ultimately, but is the rate of that reaction sufficient to overcome the rate of O3 production in the short (hours) term? It will be great when we can accurately quantitate all of the pertinent species in e.g. the LA basin with high spatial and temporal resolution and really nail things down with good data from the field rather than simplified systems in chambers.

Mike

Chingy and Joe, take it elsewhere.

Carl

George - according to some class notes I have from an atmospheric chemistry course, the "atmospheric lifetime of NO due to reaction with O3" is one minute.

Gerry

I wonder how the ULSD switch will affect the diesel prices. There were recently reports about shortage in Oregon, 3,52/gal in Washington and higher diesel prices in Canada. Does anybody have an idea how much ULSD might push the price? I mean in refining not due to (artificial?) shortage.

fred@dzlsabe.com

STFU bitches...MB 6cyl misses NOx by .01g/m WITHOUT Adblue

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