Unpleasent article from the AP on Yahoo...

Dana D.

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Scientists Blame Soot for Global Warming

By JOHN HEILPRIN, Associated Press Writer

WASHINGTON - NASA (news - web sites) scientists say soot, mostly from diesel engines, is causing as much as a quarter of all observed global warming by reducing the ability of snow and ice to reflect sunlight.

Here's the Yahoo article.

<font color="brown"> This wasn't friendly to wake up to. Response? </font>
 

saGhost

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Umm... Funny that through much of the 19th century big cities like London were turned gray with soot [from coal - this is the height of the industrial revolution] - to the point that it is still in historical pieces about the period - and yet 1913 and 1932 are the years for most of our record lows - and the winters of 1941-2 and 1942-3 were some of the worst on record, enough to freeze the Germans out of Russia. I don't buy it. [And I also don't buy the 'mostly from diesel engines' part - but that's another story]
Walter
 

nh mike

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I posted this over at biodieselnow in response to the same article. I'm just pasting it here:

Some articles to read:
http://www.findarticles.com/cf_dls/m0CYH/17_7/109443861/p1/article.jhtml
(gasoline and CNG emissions contain as much (and as bad) PM or more than diesel vehicles with DPFs (diesel particulate filters)).

Our current VW TDIs do not have these DPFs (actually, the 2004s might, I'm not sure). They make a huge difference in the soot/PM output.

An excellent report to read is this one:
http://www.vv.se/publ_blank/bokhylla/miljo/2002_62/2002_62.pdf
It's a study done by the Swedish Road Transportation Agency, taking data for comparison between modern diesel and gasoline vehicles. They looked at both regulated and unregulated emissions. The diesel vehicles used were a VW Golf TDI without a DPF (so the kind we currently have over here), and one of the newer Peugot 307 diesels with common rail injection and a DPF, to see the impact of these new diesel technologies. They were compared to the gasoline versions of the same vehicles.

The paper linked is in both Swedish and English - they do a section in Swedish first, then English, so you'll have to skip over the Swedish sections (unless you know Swedish).

Neither of the diesel vehicles tested included NOx adsorbing catalysts, since those will only be included on new vehicles once ULSD is mandated (in 2006 in the US). So, the NOx emissions were of course higher on the diesels as expected.

But, the HC emissions were considerably lower on the diesels - by an order of magnitude or more. They did the testing at two ambient temperatures - 22C (roughly 70F) and -7C (roughly 20F). At 20F, the gasoline vehicles both emitted 20 times more HCs than their diesel counterparts. At 70F, the difference was only roughly a factor of 5 - but still far more HCs for the gasoline vehicles.

From a health standpoint, HC emissions are VERY important - they contain a lot of the possible carcinogens, plus are the most critical component in smog formation (which requires HC and NOx). The EPA is wrongly focusing on reducing NOx emissions, which will probably result in an increase in smog (since without HC emissions, NOx destroys smog. California is having a weekend smog issue that goes completely against the EPA's thinking. On the weekend, there is far less diesel traffic (no delivery trucks, etc.), so much lower NOx emissions, but roughly the same amount of HC emissions (which mostly come from the gasoline vehicles). If the EPA were right about reducing NOx resulting in a decrease in smog, then California should see lower smog levels on the weekend. In fact, it's the opposite. Smog is much worse on the weekends in Calfornia - due to the lack of an excess of NOx emissiosn which destroy smog.

Next, PM emissions. The diesel vehicle without the DPF (the Golf TDI) did have considerably higher PM emissions than the petrol version. But, the diesel vehicle WITH the DPF had LOWER PM emissions than either of the gasoline vehicles tested. The DPFs make that much of a difference. Yes, biodiesel reduces PM emissions around 30-80% or so, depending on the vehicle, but the DPF can reduce those emissions roughly 99%. The gasoline version of the Peugot emitted PM levels 10 times as high as the diesel version with the DPF!!

If you look at graph ES.5, which shows particulate emissions for the US06 cycle test and an overtaking test, the gasoline vehicles emitted roughly the same level of PM as the TDI without the DPF! The Peugot with the DPF was then around 3-4 orders of magnitude lower than either of the gasoline vehicles.

The gasoline vehicles showed a higher ozone forming potential (due to the much higher HC emissions), and higher HC emissions (than the DPF diesel). What this shows is that with the new diesel technologies coming to market, they are actually CLEANER than gasoline vehicles - even on the issue of particulate matter.

All of these graphs are on pages 20-23 of the pdf.

Yes, old diesel vehicles will still emit more soot, especially if they use petro diesel. But, the skies are getting clearer.
 

wxman

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I'd also like to know upon what the assumption "soot, mostly from diesel engines" is based? Just the connotation of soot with diesels?


In addition to the sources cited by nh mike:

"...Even if these factors were reasonably accurate, SCAQMD left unaccounted 67% of the residual particulate carbon captured at air monitoring stations for PM2.5. This begs the question of what other sources contribute to the PM2.5 collected at the air monitoring stations. For example, the NFRAQS work indicated that light-duty gasoline vehicles contributed about 60% of the PM2.5 carbon measured at urban Denver sites and that these contributions were 2.5-3.0 times those from diesel."

Source: DOE


Furthermore, DPFs are effective enough that diesel PM emissions are/will become a non-issue:

"…DPF “cleans” room air [US06 cycle]…"

Source: Comparison of Direct Exposure of Human Lung Cells to Modern Engine Exhaust Particles, John Storey, ORNL, 2003 DEER Conference


"…Prof. J. Czerwinski, University of Applied Science Biel, reported on minutely done evaluations of the filter system (Faurecia), installed in the Peugeot 607 Diesel passenger car. Somewhat surprising, and from the viewpoint of measuring even an unexpected challenge, was the fact that the exhaust contained less aerosols than the ambient air…."

Source: http://www.akpf.org/pub/2002_eth_summ.pdf


"…Filters are considered effective enough such that tailpipe emissions are less than ambient levels in laboratory…."

Source: Tim Johnson (Corning), Symposium on Particulate Matter, August 12-13, 2003


If these unfounded assumptions that "soot, mostly from diesel engines" continue to be propagated (by the scientific community, no less), this "global warming" issue won't be adequately addressed, in my opinion.
 

Powder Hound

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I agree. It is unfortunate that the reactionaries quote (or make up) alarming headlines and neglect critical details. In the first article that was posted, there were 3 words at the tail end of the article, "...if we're right...". I wonder if anybody will check on this stuff.

I also noted mentions of brown haze. Isn't soot black? I've seen crud on snow in high mountains in the summer. It was made of all kinds of stuff - from dirt to algae. To find soot in that crud would have taken a gas chromatography analysis.

I noted once a couple of years ago there were a couple of weeks in Utah where the air was brown. The source was a dust storm in Mongolia that made it completely across the Pacific and across the US. It was dust. Simply brown dust. Not soot, not burning yak dung, not 10 million Monglians driving diesel Rovers. Sometimes natural phenomena do things for years before us humans get around to noticing them. (OK, the dust was noticed quickly, but it was really dramatic!)

The particulate filters available for diesels sound very promising. With the coming ULSD diesel, they ought to be available. That'll help.

Screaming about diesels and soot is sounding like R-12 scares and ozone. Many years ago, there was a scientist that found a direct correlation between an erupting volcano in the southern hemisphere and the thinning ozone layers - a coefficient better than .9 (coupled with seasonal variation in sunlight) I believe. Coefficients better than .5 are unheard of in statistical analysis, and for natural phenomena are about impossible. The study was ignored and buried because it didn't fit with crazies who wanted to do what - manipulate the economy? I don't know why it was buried, but there are those with ulterior motives.

I really hope the soot issue doesn't become an excuse for the US to become the one country in the world that hates diesels.
 

AndyBees

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Don't misunderstand me, I am really for cleaning up the environment everywhere its possible, practical, politically correct, etc. But, there is a "saying" that has been around for a few years ..... something like this .... "let the b_ stards freeze in the dark." I say that to ask this question: Should we stop the diesel powered trains, the semi-trucks, the many stationary diesel generators around the world, the buses, the heavy earth moving equipment, the jet planes, etc.? ...... well, should we? And, there are still numerous homes heated with coal stoves, wood burning stoves, fireplaces, etc., that add to the "soot" floating around in the air. Consider this, it takes particulate matter in the atmosphere for cloud formation. Check out any good science or physical geography book. Yes, it takes "dirty" air in order to rain water! .....LOL

I believe the bunk about global warming being a result of modern man ..... well, its bunk until there is solid proof. Oh, of course there are those who say that it would be too late by them ......well! /images/graemlins/grin.gif
 
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