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Author Topic: Should limits on vehicle pollutants be averaged thru driving cycle, not max PPM?  (Read 20134 times)

Offline peppercorn

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IIRC, at present the parts-per-million counts for CO, HCs and NOx in exhaust emissions are legislated to remain below maximum limits (in normal driving).

But, due to catalytic-converters being ineffective during their warm-up period, the PPM exempts a certain amount of running time.  Also, I assume that cold weather conditions, etc can lengthen this period further.

In a similar way to the take up of the combined-cycle in measuring fuel consumption, would it not be logical to develop a similar approach to particulate pollutants?

NB: I'm not saying completely remove an upper limit for instantaneous PPM counts (Big puffs of black smoke from diesels is not good!), but it could be backed off slightly in favour of a better overall full-cycle average.


 

SteveFish

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I think that the whole pollution question needs to be evaluated by an independent scientific body that would consider both vehicle lifetime and embodied energy and pollution for construction (e.g. what does it take to make a catalytic converter). The harm from each of the pollutants should be considered when setting relative and absolute limits.
 

Offline CliffordK

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I agree that the vehicle emissions need to be re-evaluated, and it should be more comprehensive than just targeting the lowest possible concentration.

There are issues of cumulative concentration of pollutants, especially in urban areas.  Thus, while a Catalytic Converter or similar device may be energy intensive to manufacture, it may be effective with displacing CO and NOx out of the urban areas.  Perhaps it isn't a big issue for Rural residents, but still potentially an issue for suburbanites and those living in satellite communities.

However, other issues should also be considered including whether the emissions equipment adversely affect fuel efficiency including the burnoff cycles with the DPF.  Of course, noting that efficient emissions often uses a combination of excellent engine tuning plus the devices such as a CAT.

Also, rather than just basing everything on relative concentration, the standards should also take into account overall output.  Thus, a Diesel Hummer wouldn't be favored over a Diesel Smart Car due to emission concentration while the Smart puts out only a fraction of the total emissions of the Hummer.

More effort needs to be put into merging global emission and Safety standards.
It is ludicrous that it is illegal for an American to buy or import European cars that are built to excellent standards, and get over 70 MPG.

As far as maintenance on aging vehicles.  It can become astronomically expensive to repair the emission system on a 20+ yr old car that only gets driven a few thousand miles a year.  St. Louis has exempt all pre-ODB II vehicles which is a step forward.  But, the 20+ yr old vehicles are the minority of the vehicles on the road, and they usually get driven less than the newer vehicles.  Standards should be made not to put undue hardship on the owners.  One might have to look at it, but I don't believe the older vehicles are a major contribution to the overall emissions output.
 

Offline peppercorn

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Also, rather than just basing everything on relative concentration, the standards should also take into account overall output.  Thus, a Diesel Hummer wouldn't be favored over a Diesel Smart Car due to emission concentration while the Smart puts out only a fraction of the total emissions of the Hummer.

Agreed. This is a good point indeed, if PPM is based on overall consumption (more specifically air/fuel through-put), then there is (relatively) much more room for manoeuvre for large displacement vehicles than for small.  This seems counter to where we should be heading.


As far as maintenance on aging vehicles.  It can become astronomically expensive to repair the emission system on a 20+ yr old car that only gets driven a few thousand miles a year.  St. Louis has exempt all pre-ODB II vehicles which is a step forward.  But, the 20+ yr old vehicles are the minority of the vehicles on the road, and they usually get driven less than the newer vehicles.

I should say that I suspect that the majority of emissions-linked service costs are roughly dependent on miles driven, so the costs to the owner are fair.  However I do agree (very strongly - having a classic motor myself) that encouraging drivers to, blindly, move to replace their 10+ year old cars, is not always the best thing it terms of carbon.

In the UK older vehicles have been except from emission testing since its introduction (beyond a visual 'black-smoke' check) and this seems a fair balance.  I have heard that emission tests may be phased out altogether, but am not sure of the thinking behind this (if true - It won't change my MOT test either way).

I do think aspects like DPF burn-off cycles should be factored in as part of a proposed full driving-cycle calculation for particulate count.  I don't suppose these cycles are a particularly regular occurrence (unless some engine component is faulty), but it does seem bazaar that current legislation is only concerned with normal running conditions (not warm-up or purge cycles) in producing the figures.

I believe their are also separate rules on commercial vehicles (even those used for purely private motorists) w.r.t. PPM and CO2 counts - Again illogical IMO.  Especially since, for say a small van, the entire drive-train is identical to the factory's cars.
 

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Offline yor_on

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Heh :)

Stop using cars
But.
Let the bikes be :)

The 'Real ones' of course, not those black ugly ones..
 

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Offline yor_on

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Big black ugly ones I meant..

heh.

.. Censured at last :)

Tells you what bike he drives :)
« Last Edit: 03/12/2010 02:20:42 by yor_on »
 

SteveFish

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peppercorn:

In this thread you are questioning parts per million (PPM) as a valid measure of auto exhaust pollution, which I also think is not just invalid, but just plain stupid. However, on your other post in Physical> Tech> "Do our cars really need CATs" (catalytic converters) you were talking about the regulations as specifying grams of pollutants per mile GPM). PPM is a ratio such that a small engine that measures the same as a large engine, would actually be releasing much less pollution. GPM is an absolute measure where engines would be fairly rated on the basis of the total pollution they release. Please explain.

Steve
 

Offline peppercorn

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...Please explain.
Steve

Would that I could Steve :D
I guess I had better go check my sources!
Can someone confirm what the -US- EPA uses in their standards?
GPM is obviously the better descriptor, but I had thought I'd also read limits in PPM. ???
 

Offline CliffordK

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Here is a chart of Diesel Fuel Standard Changes over the last fuel years.
Both EPA, and European Union. 
(posted on a Ford website earlier, I think).
http://www.slideshare.net/FordMotorCompany/diesel-forum-presentation

Height of the bar is NOx.
Width of the bar is Particulate Matter.

They are listing them in g/HP-hr or g/KW-hr

So, this seems to be based on the instantaneous HP output of the engine, which may actually be somewhat fair, although it does set a very low bar for the low HP vehicles, especially those running with a small engine near max HP output.

Oh... Man...  Now my head is spinning   ::):o [B)] [xx(]

I'm pretty sure my previous EPA testing reports were all in PPM.  However, the actual "requirements" are essentially impossible to track down so perhaps they are being dynamically calculated for each vehicle.  So that if one went to a mechanic, the ppm would be easy enough for the mechanic to measure.  I'll see if I can find some old reports later.

Previous tests were always done on a dynamo rollers...  but the last time I had my car tested, it was done only at idle.  I've never had a car that was newer than 1991 tested though.  Perhaps things have changed.

It looks like there are standards in:
    gm/HP-hr or gm/KW-hr
    As well as gm/mile

Cars are also broken down into the categories:
    Low Emission Vehicles
    Ultra Low Emission Vehicles
    Super Low Emission Vehicles
    Partial Zero Emission Vehicle
    Advanced Technology Partial Zero Emission Vehicle
    Zero Emission Vehicles (Electric)

With all of those categories, they have weights of
    < 8500 lbs
    8501 to 10,000 lbs
    10,000 to 14,000 lbs
    (and I assume heavier)

They also seem to have values for a "Durability Basis" of vehicle miles with slightly more lenient values for cars over 120,000 miles:
    50,000 miles
    120,000 miles
    150,000 miles

Anyway, here are all the California Testing Standards which seem to be the basis for most of the EPA SMOG testing, at least in Oregon too.

http://www.arb.ca.gov/msprog/levprog/cleandoc/cleancompletelevregsasof8-14-04.pdf

Here is a book on Google Books, "Air Pollution for Motor Vehicles"
Chapter 1 summarizes the emission standards by country.
http://books.google.com/books?id=Hqsyv_KD0lgC&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
 

SteveFish

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I am also frustrated by trying to figure this out. The fact that this should not be difficult in contrast to the fact that it is, is the reason I have a very suspicious attitude about US pollution standards and the potential nefarious lobbyist input into our laws. Grams/hp or KWh is just a way to scale a small, lightweight car as equal to a giant, heavy one, when actually the larger car is releasing many times the amount of actual pollution.

The people who want to have their monster car should have to pay for the extra damage to all the rest of us they cause.
« Last Edit: 03/12/2010 16:05:35 by SteveFish »
 

Offline Bored chemist

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The efficiency of the engine tallies quite well with the ppm of pollutants in the exhaust.*
Since they are seeking to improve efficiency that's what they measure.
The fact is that mopeds and 4by4s simply aren't the same thing. You cannot directly compare miles per gallon for the two.

Don't forget that the gas guzzlers already pay more tax because they use more fuel (which is heavily taxed).

* an ideal, lean-burn engine would produce about 140000 ppm CO2, 0 ppm NOx, 0ppm CO, 0ppm hydrocarbons and zero ppm SOx no matter whether it was diesel or gasoline and whatever the engine capacity.
 

Offline peppercorn

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The efficiency of the engine tallies quite well with the ppm of pollutants in the exhaust.*
Since they are seeking to improve efficiency that's what they measure.
The fact is that mopeds and 4by4s simply aren't the same thing. You cannot directly compare miles per gallon for the two.

Don't forget that the gas guzzlers already pay more tax because they use more fuel (which is heavily taxed).

* an ideal, lean-burn engine would produce about 140000 ppm CO2, 0 ppm NOx, 0ppm CO, 0ppm hydrocarbons and zero ppm SOx no matter whether it was diesel or gasoline and whatever the engine capacity.

I was under the impression that keeping NOx down was the hardest thing in lean-burn due to peak cylinder temps.  A lean-burn with hybrid could potentially only need a single 'one-way' cat.... ?

I think that, although you're right about comparing mopeds with 4x4s, it's no bad thing to add a further incentive to downsize displacement (providing it's a fair incentive going back to my OP).  Currently the US & others still have very lenient taxation for 'gas' and, although (in a world of only rational consumers) tax at the pump is by far the fairest, I think other ways (inc. legislating at manufacture) are required for fast and effective change.
« Last Edit: 03/12/2010 17:46:21 by peppercorn »
 

Offline Bored chemist

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I didn't say that an ideal lean burn engine (or anything close to it) exists ;-)  .

I worry about the idea that only rich people will be able to afford to poison poor people. However, tax at the pump sees to be the least bad option.
 

SteveFish

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To clarify what I am saying- Percent pollution doesn't mean squat, it is the amount that counts and this is what should be taxed whether it be a moped or a large truck. This is the only way to represent the real cost of using fossil fuels.
 

Offline Geezer

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Currently the US & others still have very lenient taxation for 'gas'


A typical Eurocentric view IMHO. Tax the heck out of it, and if that doesn't work, tax it even more  ;D

Considering the UK is a net exporter of oil, I'm a bit surprised there hasn't been a blinking revolution over the ridiculous amount of tax that's levied on petrol.
 

SteveFish

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Geezer:

My view is very definitely of the US. There are some in my country who think, like (hopefully decreasing numbers of) economists, that such things as water depletion, pollution damage, resource depletion, and any other cost to the commons should be ignored. These costs are called "externalities" by old time economists, but this practice cannot continue. This rapacious attitude allows large business to do major cost shifting to all the rest of us for their own benefit. I am very patriotic and am very concerned about this anti American attitude.

Steve
« Last Edit: 04/12/2010 21:55:21 by SteveFish »
 

Offline Geezer

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Steve:

Who said anything about encouraging the depletion of natural resources? All I said was taxation is not a very effective tool. It's not working very well in your home state (I've lived there and in Europe BTW) which is about to go bust despite (or perhaps because of) the enormous burden it places on its productive citizens, which is not unlike the typical European model.

Geezer
 

Offline peppercorn

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This is going a bit 'off topic', don't ya think guys?
The point is taxation (of whatever flavour or mix) doesn't appear to work alone.
Redefining the air-quality and emissions laws should ensure that car manufactures are 'encouraged' to make and sell cars with efficient (and non-bloated) engines without the need of complex bolt-on (hidden-) tax incentives (that just cause bureaucratic waste).
 

Offline Geezer

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This is going a bit 'off topic', don't ya think guys?

Sheesh! You started it with the tax stuff  ;D  ;D
 

SteveFish

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I don't really care about how important realities are dealt with. What I do care about is resource depletion and environmental degradation. I am especially concerned that nobody wishes to put a cost on using the rapidly diminishing commons. We are approaching another tragedy of the commons and problems with automobile emissions and fuel usage are a sizable component. (Geezer, my taxes are really quite reasonable).
 

Offline Geezer

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I don't really care about how important realities are dealt with. What I do care about is resource depletion and environmental degradation. I am especially concerned that nobody wishes to put a cost on using the rapidly diminishing commons. We are approaching another tragedy of the commons and problems with automobile emissions and fuel usage are a sizable component. (Geezer, my taxes are really quite reasonable).

I agree Steve (except for the tax bit  :D) What we really need to do is re-engineer the whole process. A very significant amount of fossil fuel is being spent by people simply going to and from their places of work. We might say that can be solved by the use if public transport, but, actually that's not necessarily true. For example, the real energy costs associated with rail transport are actually a lot higher than some people think (I'll probably need to dig up some data to justify that statement!)

I think figuring out methods to eliminate a lot of commuting entirely ought to be a high priority. That's just one example of course. Now I'll probably get beaten up by Peppercorn for derailing his thread again  ;) 
 

Offline peppercorn

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Lol! - 'derailing', what are you like?!
I would like to see these figures on Rail, but even if they are high right-now I can't think of any good reason why that has to be the case - if it's down to running lots of trains too empty then it;s time to do something about that.

I'm always amazed by how many vehicles are whizzing around during the middle of the day, and not just delivery vans, etc.  In short it;s not just work traffic (although this cases the majority of jams [or is it the school run?!]) - people don;t think twice about using the motor vehicle, but I agree that changing peoples behaviour is not just about levying ever higher taxes.
 

Offline Geezer

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I'll see what I can did up on the rail thing. I seem to remember it's not just the underutilization of capital equipment, but the actual energy consumed per person mile is really quite high. I was quite surprised when I read it myself. Unfortunately, I've no idea where I saw it now.

It's an interesting example of how it's always a good idea to challenge the conventional wisdom. (You may have noted a certain tendency to do that on my part.)
 

Offline CliffordK

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Wikipedia had a good article on the costs of public transportation vs cars.  Obviously one of the big issues it the typical 1.5 people per car.

http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation

I think it is heavily US modeled, but down at the bottom there are also some UK links.

http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation#UK_Public_transport

The problem is that for public transportation to be practical, there has to be access.  I.E.  A bus should go within 1/4 or 1/2 mile of every place in the city, and should do it from about 5AM to 2AM.  Doing so, one ends up with a lot of buses circling the city empty. 

The public transportation companies don't seem to like to have a mix of, say typical 15 passenger vans, plus large buses.  Run the small vans on off-peak hours, and the big buses during rush hour.

Same thing for commuter trains.  They are worthless if you don't have access.  So the average ridership is low.  Although, this would vary a lot from community to community.  In many parts of the world, there aren't other "alternatives", and they also make schedules to try to keep the trains full.

One efficient "commuter" train system that I've been on was the Seattle Tacoma "Sounder"

http://www.soundtransit.org/x71.xml

What is unique about it is that it only has northbound trains in the morning and southbound trains in the evening (it looks like there are a couple more options now for reverse commuting).  When I was on it, the train was packed for most of the trip.  And it appears as if they've added several more trains in the last couple of years. 

I assume they have "train barns" at either end so with the exception of the reverse commutes, most of the trains run one way twice a day, with perhaps one or two trains running 3 ways.

Sorry, I don't have actual ridership and efficiency figures for the Seattle Sounder system.  It just seemed packed when I was on one of the trains a couple of years ago, and it appears as if the system has expanded since then.
 

Offline Geezer

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Thanks Clifford.

The one that's very significant is the "efficient hybrid" from the US Passenger Transportation in the Wiki page. If these figures are to believed, it's almost twice as energy efficient as commuter rail links in the US.

I do have a personal bias in favor of all forms of rail transport, but I suspect these figures don't even take into account the depressingly low capital utilization of commuter trains and rail infrastructure. Apart from rush hours, most of the stuff is grossly underutilized.
 

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