diesel emmisions

[jkh]

I am in a disussion with my niece about which is worse for the environment... gas or diesel.

I read on here a while back that you could stand in a garage all day with a diesle running, but a gas engine would kill you. Can someone expand on this a little so I make sure i have my info. correct when I see her again.

I think it has something to do with carbonmonoxide, but I don't want to say that till I'm sure.

Thanks.

 

[HBarlow]

Don't waste your time. Your niece has already been propagandized by her teachers and her peers. No amount of factual information is going to overcome her leftist bias until she matures and begins to understand the real world.

 

[rscurtis]

Right now, the exhaust from either is clean enough to breathe. In some locations, the air from the exhaust is cleaner than the air going in.



However, running a vehicle in an enclosed space will eventually use up the oxygen in the air, leading to the formation of CO.

 

[Regcabguy]

The worst pollution factor by far is what China and India spew into the atmosphere daily. Nothing we drive here even compares. It's a non-issue.

 

[ata]

HBarlow has it right. But CO from a gas engine will kill you quick and NOX from a diesel will give cancer and kill you slow. CO from a gas engine will kill plants and animals NOX from a diesel only kills animals. (slow) A diesel has little CO compared to a gas engine but it will get you if you stand there long enough.

 

[jkh]

thats what I thought from what I have read about it. But you guys are right, it is hard to change someones perception with facts when they already think they know everything they need to about the subject.

It will still be fun to try, next time i see her.

 

[MLee]

JkH, she is convinced of her belief and ideas because you can't see the cars exhaust BUT can see the diesel exhaust. So to her it is more dangerous. If you can see it its more dangerous type of idea. How else are we going to get our Diesel fix daily if we can't see it? LOL

 

[MChrist]

Does anybody here know for sure what black soot really is?? I keep hearing that it's carbon, but am not positive.

 

[Simplysmn]

Isn't the Black soot they we see out the tailpipe just Unburnt fuel ?

 

[MChrist]

Isn't the Black soot they we see out the tailpipe just Unburnt fuel ?

No. Unburnt fuel shows up as a light blue haze. Fuel that has gone through the combustion process without enough air to burn it completely is black. My question is: What exactly is the black soot? Carbon seems like a good answer, but I'm just not sure.

 

[BIGNASTY]

over fuel ?

This is just a weeeeeeee bit over fueled :-laf

 

[AABEN]

Black is over fueling that is not burning If it is blue it is oil white is vapor.

 

[MChrist]

Lingering blue smoke is oil, light blue that diminishes quickly is unburnt fuel. I repeat: BLACK SMOKE is fuel that has burnt, it just had a very low air volume to burn completely (thoroughly). I know that everybody says black=unburnt, but it is far more accurate to say it hasn't burned completely.

If black = unburned fuel, why do trucks that blow smoke always have high EGTs? Hmmmmmm? That, among other reasons, shows why that is wrong.

 

[richardcoxid]

Just tell her that in Europe more than 50% of the vehicles are Diesel. The Europe EPA says that a Diesel engine is easier to clean up, here in the USA the EPA says that Gas is easier to clean up.



So to me it is actually anybodys guess when the so called EXPERTS can’t even agree!

 

[rscurtis]

I wouldn't categorize the EPA as "experts". They're obstructionist bureaucrats.

 

[EDankievitch]

Ok, in answer to your question... ... . A diesel engine almost always has a O2 rich fire unlike a gas engine. The speed of the engine is controlled by the amount of and timing of the fuel injected into the cylinder. A gas engine speed is controlled by the throttle plate in the intake. Closing the throttle plate causes the engine to run lean on O2. Not enough O2 causes the fie to make Co (carbonmonixide) An oxygen rich fire will make Co2 carbondioxide, wich is what we exhale when we breathe. The problem with carbonmonixide is that the blood does not release it so it stays and builds up in our body systems until it kills us. Carbondioxide can kill you also if there is no oxergen to beath. It's never a good idea to run any engine in a enclosed space.

 

[jkh]

Don't worry Ed, i'm smart enough to know not to run an engine inside. I was just quoting an analogy that someone used on here years ago to describe how diesels are not as dangerous as every one thinks they are. People see the black smoke and right away it has to be worse than a gas engine because they don't make black smoke. I new I could get more informative answers on here, yours explains what I didn't know about the CO and CO2.

Thanks Ed.

 

[rbattelle]

A gas engine speed is controlled by the throttle plate in the intake. Closing the throttle plate causes the engine to run lean on O2.

That is incorrect. Spark ignition engines run to a constant FAR. Closing the throttle plate reduces fuel flow rate at constant FAR.



The answer to which "pollutes" more is "it depends on the definition of pollution". Gas engines produce more CO2, but diesels produce more NOx and particulates.



In Europe, emissions regulations "credit" the diesel for its reduced CO2, effectively tolerating the increased NOx and particulates in exchange for lower CO2. In the US, the EPA forces the same emissions levels on both engine types.



-Ryan

 

[wxman]

There are objective data which show that the new "clean diesels" have generally lower emissions than equivalent gasoline engines.



For example, certification data of the GM 6. 6 liter diesel engine (http://www.arb.ca.gov/msprog/onroad/cert/mdehdehdv/2012/gm_mdde_a0061801_6d6_0d46-0d01.pdf) has lower emissions than their 6. 0 medium-duty gasoline engine (http://www.arb.ca.gov/msprog/onroad/cert/mdehdehdv/2012/gm_mdoe_a0061797r1_6d0_0d42.pdf) except for NOx (0. 32 g/hp-hr vs. 0. 19 g/hp-hr).



There is also an extensive report on emissions (both regulated and non-regulated) from 4 large 2007-compliant over-the-road diesel engines (http://www.crcao.org/reports/recentstudies2009/ACES Phase 1/ACES Phase1 Final Report 15JUN2009.pdf).



Furthermore, "upstream" (well-to-pump - WTP) emissions of gasoline tends to be much higher than WTP emissions of diesel fuel. Here is a graphic of well-to-wheels (WTW) emissions of the PZEV version of a 2012 Volkswagen Passat and 2012 Passat TDI combining certified exhaust (pump-to-wheels - PTW) emissions and WTP emissions based on Argonne National Laboratory's GREET model. Regulated emissions associated with the TDI are lower across-the-board than the PZEV-certified version...





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[rbattelle]

That's some nice data, wxman. Interesting WTP/PTW ratio for CO and SOx.

Where did they assume the well is? Does "pump" mean the consumer dispenser, or the one at the fuel farm?

-Ryan