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Old 02-18-2012, 08:08 AM   #141 (permalink)
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Originally Posted by mechman600 View Post
Diesel exhaust temps are lower nowadays because of this high amount of EGR (30-50%) used to significantly lower NOx. An older, non-EGR diesel will have much higher exhaust temps (at full load) than a gas engine. Gas engine exhaust temps remain fairly constant because of near stoiciometric mixtures. Diesel engine exhaust varies wildly, as you've stated above. An older (dirty) diesel can be >1200F at full load on its own.

Gas engine CAT: 3-way cat. Converts HC, CO, NOx to "nicer" things. Works whenever the engine is running and is hot enough to do so. Requires stoiciometric.

Diesel engine CAT: 2-way cat. Only oxidizes HC in order to regenerate the DPF. Cannot remove NOx because of lean diesel operation. To elevate exhaust temp at light loads, the ECM closes the VGT to create back pressure, stops all EGR flow and retards the timing to get turbo out temps above 550F. Then it either injects fuel in-cylinder during the exhaust stroke or uses an HC doser on the turbo outlet to spray raw fuel into the CAT (called a DOC, diesel oxidation catalyst). It doses enough HC to maintain 1000-1100F to allow the DPF (attached to the DOC) to regenerate. Regeneration only occurs once every 8-15 hours of operation, otherwise the CAT is basically doing NOTHING but going along for the ride.
What you described is DPF regeneration, but my turbodiesel doesn't have a DPF, yet it has a catalyst. What for?

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Old 02-19-2012, 07:05 PM   #142 (permalink)
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Originally Posted by Piwoslaw View Post
What you described is DPF regeneration, but my turbodiesel doesn't have a DPF, yet it has a catalyst. What for?
Oxidizing CO and HC, to CO2 and H20 .

Some of the particles also get oxidized (read : burned).
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Old 02-20-2012, 01:34 PM   #143 (permalink)
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I'm about to close the book on my P&G chapter. I built and managed legal cases for a living. IMO, we have a preponderance of evidence proving EOC P&G pollutes the air we breath. Ergo, I'm not going to do it, just as I don't litter and I don't steal.

I took my wife to her college today, and out to Valentine's Day lunch. The drive is poor city driving that used to average low 40s mpg. I got mid 30s mpg.
I recommend doing some lite reading.

http://southdakota.sierraclub.org/Li...refineries.pdf

I attempted to do something I rarely do, group evidence I've encountered over the years into a nice neat package for you to read (actually I've wanted to do it for a while) Sadly I get an
EPIC fail, some of the nice papers on ocean going ships so an nox pollution isn't at my fingers.

Anyway Over the last 10 years all the info I have read is that the pollution as you define it (aka not CO2) emitted from refineries and transport of fuel on a per gallon basis likely exceeds what your car even running dirty emits.

No6 bunker fuel has tremendous sulphur QTYs and the ocean going ships make as much Nox on a per gallon basis as a 70's benz out of tune. Much of it in the ocean but I believe still worth tallying against the supply side.

Refineries also emit tremendous amounts of benezene, NOX, sulphur and other compounds that are very high if referenced on a per gallon basis of gasoline out.

Now I will shut up until I can find a nice cookie cutter set of data for somebody to look at.

I am still surprized no one has put something together on this regard, they only look at the energy efficiency but not the pollution output on a nox, so2, benezene, etc basis to put next to your pollution chart from your car.

Then again we live in the guilded age of looking like we are green so long as we don't do the numbers on all the stuff upstream from us.

I prefer to not be nieve, ah well.
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Old 02-20-2012, 08:17 PM   #144 (permalink)
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Thanks very much for not giving up on me!

I am revisiting the issue after reading this article, which states "April 23, 2009 The Guardian has reported on new research showing that in one year, a single large container ship can emit cancer and asthma-causing pollutants equivalent to that of 50 million cars," and "15 of the world's biggest ships may now emit as much pollution as all the world's 760m cars."

Certainly my paltry 226 gallons of gasoline burned last year and 11,650 miles driven aren't even a hiccup of a giant cargo ship's pollution: 1/50,000,000 of that cargo ship's pollution, if it runs its engines 24/7, is .63 seconds. It emits more in .63 seconds,\ than the average car does in a year. Even if my car emits 75X more HCs than the average car, its annual HC output isn't a minute of the cargo ship's annual pollution.

If someone could quantify the claims about the amount of air pollution the refineries produce to produce my 226 gallons of gasoline, or other examples of how insignificant my personal pollution is, I'm teetering on the brink of coming back.

I'm still trying to wrap my mind around how much of a problem 80 million pounds of unreported volatile organic compounds is. If my 226 gal. of gasoline = 1356 lbs of VOC, that's one thing, but if we're talking about those 226 gallons equaling 25,764 lbs of CO2, with 40 million cars in CA, 80 million pounds isn't that much.
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Old 02-20-2012, 08:27 PM   #145 (permalink)
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darrell,
life is full of trade offs.

at the same time you don't want to feel like your being stupid in doing one thing because of your acute awareness of something else.

An extreme example of that is howard hughes !!

You certainly have increase our awareness of the tradeoffs!
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Old 02-20-2012, 09:54 PM   #146 (permalink)
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SentraSE-R -

Quote:
Originally Posted by SentraSE-R View Post
...

If someone could quantify the claims about the amount of air pollution the refineries produce to produce my 226 gallons of gasoline, or other examples of how insignificant my personal pollution is, I'm teetering on the brink of coming back.

...
I think we need to at least find the *range* of min/max pollution being claimed in all these studies and go from there. Maybe there's something to find at Rocky Mountain Institute :

Rocky Mountain Institute

For instance, here is an article :

ABATING AIR POLLUTION AT NEGATIVE COST VIA ENERGY EFFICIENCY
Abating Air Pollution at Negative Cost

With reference at the back of the article.

CarloSW2
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Old 02-21-2012, 12:06 AM   #147 (permalink)
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Thanks Mark y Carlos,

I found a fairly comprehensive analysis here. There are 67 pages in the transportation chapter, and the Transportation Life Cycle Analysis proves that diesel is ~20% less costly in life cycle costs. Unfortunately, I couldn't find a separation of production/shipping cost (upstream cost) v. on-road cost (downstream cost) in the life cycle analysis.

Just a WAG tells me you LCA guys are right. If we're employing fleets of supertankers to import millions of barrels of crude oil from the middle east annually, what is the cost? 160 million bbls/yr from Saudi Arabia alone = >160 shiploads X 6000 miles each way (at 20 mph X 24 hrs/day) X 25 days RT each. That's 4000 days of supertanker operation, or 10.95 supertankers' annual pollution - as much as 547 million cars would produce in that same year. Add other middle east exporters we buy from, and it's easy to see transportation pollution just for middle east crude exceeding all our US car-produced pollution.
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Last edited by SentraSE-R; 02-21-2012 at 12:13 AM..
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Old 02-21-2012, 12:37 PM   #148 (permalink)
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Quote:
Originally Posted by SentraSE-R View Post
I am revisiting the issue after reading this article,
I wonder why the article targets Maersk - a company that's doing more than it officially needs to, to reduce the impact of its operations.

But their fuel use and emissions needs to be reduced, that's for sure.
Both the US and EU are actually doing just that.

If a company tries to do a lot better, it'll price itself out of the market - a market driven by all of us, wanting our stuff cheap even if it comes from the other side of the world.

Quote:
Certainly my paltry 226 gallons of gasoline burned last year and 11,650 miles driven aren't even a hiccup of a giant cargo ship's pollution
No, but there's lots of cars, and they don't do what these ships do : moving massive amounts of stuff over huge distances.
Do that using trucks, and the picture would be even bleaker.

These ships need like 85% loading or they're operating at a loss.
How many trucking companies have 80+ % loading ratios ?
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Old 02-21-2012, 08:07 PM   #149 (permalink)
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I could imagine refineries, shipping, etc. of fuel to release more pollutants than the cars themselves, but those operate further from populated areas, so the health risks are smaller.

Does anyone have comparisons between HC emissions and NOx? Knowing how toxic HC emissions can be, the emphasis on NOx is a bit surprising to me when NOx is less persistent in the environment.
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Old 02-21-2012, 08:18 PM   #150 (permalink)
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Another interesting read
http://www.jernkontoret.se/energi_oc..._fuel_2015.pdf

up to 4.5% of the fuel is sulphur, the low sulphur bunker fuel @ .5% is still a factor of 10000 times more than typical auto fuel.

no telling what ppm that actually translates to but its astronomical.

i can only image what the pollution profile really looks like.

Quote:
Originally Posted by serialk11r View Post
I could imagine refineries, shipping, etc. of fuel to release more pollutants than the cars themselves, but those operate further from populated areas, so the health risks are smaller.

Does anyone have comparisons between HC emissions and NOx? Knowing how toxic HC emissions can be, the emphasis on NOx is a bit surprising to me when NOx is less persistent in the environment.
yes I agree with the above, the trouble with NOx is that it is highly reactive and if presented with HIGH VOC forms nasties and smog, however modern cars should not have High levels of VOC like the cars of the 60's but it could still be an issue in heavily populated urban areas, I figured if they would mist the exhaust the NOx would react with the water and not be able to interact with VOC relagating it to eventually form fertalizer, might eat cement roads with enough traffic though.

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