Are Diesel cleaner than Gas cars?

croppz · Nov 3, 2015

VW admitting that CO2 and MPG figures on 800,000 gas powered cars could be wrong as well...

diesel55 · Nov 3, 2015

To add to wxman's super analysis, gasoline emissions get worse over time compared to diesel emissions. This factor pushes gasoline CO much higher than diesel over time.

RalphVa · Nov 3, 2015

I'd like to see gasoline and diesel emissions compared on an equal basis, e.g. by looking at the total emissions from crude to road. We should have the technology to do this now.

I'll bet diesel comes out a winner because I'll bet it still takes a whole lot less processing than does gasoline.

Might be different for USA vs. Europe. Probably depends on ratio between diesel and gasoline that has to be processed.

Got Haggis? · Nov 4, 2015

croppz said:
VW admitting that CO2 and MPG figures on 800,000 gas powered cars could be wrong as well...

apparently quite a few of those are diesels as well (euro only)

Perry01 · Nov 6, 2015

My neighbor, who drives a Prius asked me how I felt driving our Golf TDI because it pollutes so much. She said I would be better off driving my Touareg because it uses gasoline.

If she only knew that it has a V8 FSI under the hood that only has to meet emissions standards of a light duty truck &#55357;&#56887;

VeeDubTDI · Nov 7, 2015

I'd like to know how you feel about having such an ignorant (and vocal) neighbor.

Perry01 · Nov 7, 2015

I'm used to her being outspoken but until now, I didn't know how ignorant she really is

.

jhinsc · Nov 9, 2015

I wonder what the total 'emissions' footprint is of diesel vs gasoline, when you start from the point of pulling a barrel of oil out of the ground, going through the refining process of creating a gallon of diesel vs gasoline, and adding the comparison of diesel mileage in similar cars - let's say between a Passat TSI and a Passat TDI. Maybe it was already done, but I'd be curious to see the whole picture.

wxman · Nov 9, 2015

jhinsc said:
I wonder what the total 'emissions' footprint is of diesel vs gasoline, when you start from the point of pulling a barrel of oil out of the ground, going through the refining process of creating a gallon of diesel vs gasoline, and adding the comparison of diesel mileage in similar cars - let's say between a Passat TSI and a Passat TDI. Maybe it was already done, but I'd be curious to see the whole picture.

Based on the latest version of the GREET model (GREET_2015) for "upstream" emissions (well-to-pump - WTP) and the vehicle emissions (PTW) of the Passat TDI based on the ICCT/WVU study, here is a comparison of the Passat TDI vs. the Passat 1.8T (using certified emissions of the PZEV version)...

Based strictly on the certified emissions...

wxman · Nov 9, 2015

Based strcitly on EPA emission factors (well-to-pump and pump-to-wheels), here is a comparison of generic gasoline vs. diesel WTW emissions...

jhinsc · Nov 9, 2015

jhinsc said:
I wonder what the total 'emissions' footprint is of diesel vs gasoline, when you start from the point of pulling a barrel of oil out of the ground, going through the refining process of creating a gallon of diesel vs gasoline, and adding the comparison of diesel mileage in similar cars - let's say between a Passat TSI and a Passat TDI. Maybe it was already done, but I'd be curious to see the whole picture.

I've seen the charts comparing certified emissions, but I was curious to see the total emissions created from pumping a barrel of oil out of the ground, the refining process to diesel and gas, and the number of barrels per year consumed, sort of like a 'cradle to grave' comparo for a barrel of oil between a TDI and non-TDI.

wxman · Nov 9, 2015

The yellow portion of those bars in the graphics includes emissions generated from the drilling of the well, well infrastructure, processing the fuel, and distributing the fuel.

If you want to compare by gallon or barrel, multiply the diesel WTP emissions by 1.2 (WTP emissions assume the diesel is 20% more efficient per unit of energy than the gasoline vehicle; the WTP emissions are a function of fuel consumption).

Edit: If you are really interested, the GREET model is available at https://greet.es.anl.gov/ . It can be downloaded to your PC (Excel based). Requires registration, but it's free.

wxman · Nov 9, 2015

According to GREET1_2015, here are the well-to-pump emissions in grams per million BTU of fuel available at the fuel pumps (including drilling the well, well infrastructure, and pipeline construction)...

Emission................................Gasoline (E10)...........................Diesel (ULSD)

GHG........................................19,751.....................................18,125
VOC........................................31.567......................................9.615
CO..........................................30.197......................................24.416
NOx.........................................44.983.....................................35.327
PM10........................................ 4.334.......................................2.985
SOx.........................................42.522......................................27.646

B25guy · Nov 11, 2015

Is "diesel" becoming a bad word?

This may not be the correct forum but reading a press release from Airbus today (they bought Eurocopter) regarding flight testing "...high-compression engine...piston engine uses widely-available kerosene fuel." The rest of the article goes on to describe 50% lower fuel consumption,double the range as well as an advanced "self-ignition" engine.

Is it me or did this press release go out of its way to not say Turbo Diesel or TDI???

www.rotor.org/rotornews/nov15/airbuspiston.pdf

or this one

http://www.rotor.org/Publications/R...ests-with-High-Compression-Piston-Engine.aspx

bizzle · Nov 11, 2015

I'm not sure if you think it did, but TDI doesn't stand for "Turbo Diesel"

and those engines are running on kerosene, not diesel.

cevans · Nov 11, 2015

Perry01 said:
My neighbor, who drives a Prius asked me how I felt driving our Golf TDI because it pollutes so much. She said I would be better off driving my Touareg because it uses gasoline.

If she only knew that it has a V8 FSI under the hood that only has to meet emissions standards of a light duty truck ��

Right, this is the thing that makes me the most upset about this whole thing: the regulations are meaningless.

If cars can only pollute X but trucks can pollute XXX and there is no restriction on trucks sold vs. cars then this isn't a system that encourages emissions reductions.

Being at TDIParts/IDParts now for almost a decade, I cannot count how many long time customers are workmen and use their Sportwagens as "trucks" instead of an F150 etc.

So, in this system, those who choose to get the Sportwagen to save $$ on fuel are punished versus those who choose to buy the truck. Its actually WORSE - due to CAFE standards they need to sell the fuel-efficient cars, and those who purchase the fuel efficient cars are in a sense subsidizing the sales of pickup trucks. The Sportwagens have been labeled as "polluters" and are required to have complicated and expensive emission systems to meet some arbitrary NOx numbers. Gasoline powered trucks, nope.

What kind of system is this? This isn't a democrat vs. republican thing - if the administration is serious about pollution, be serious about it, don't set up a paper swiss cheese system. Otherwise, just get out of the way and stop punishing the wrong people.

meerschm · Nov 13, 2015

cevans said:
Right, this is the thing that makes me the most upset about this whole thing: the regulations are meaningless.

If cars can only pollute X but trucks can pollute XXX and there is no restriction on trucks sold vs. cars then this isn't a system that encourages emissions reductions.

Being at TDIParts/IDParts now for almost a decade, I cannot count how many long time customers are workmen and use their Sportwagens as "trucks" instead of an F150 etc.

So, in this system, those who choose to get the Sportwagen to save $$ on fuel are punished versus those who choose to buy the truck. Its actually WORSE - due to CAFE standards they need to sell the fuel-efficient cars, and those who purchase the fuel efficient cars are in a sense subsidizing the sales of pickup trucks. The Sportwagens have been labeled as "polluters" and are required to have complicated and expensive emission systems to meet some arbitrary NOx numbers. Gasoline powered trucks, nope.

What kind of system is this? This isn't a democrat vs. republican thing - if the administration is serious about pollution, be serious about it, don't set up a paper swiss cheese system. Otherwise, just get out of the way and stop punishing the wrong people.

The laws are written by congress.

the president then signs and then applies the laws.

(so put the blame where it belongs)

roflwaffle · Nov 14, 2015

Perry01 said:
My neighbor, who drives a Prius asked me how I felt driving our Golf TDI because it pollutes so much. She said I would be better off driving my Touareg because it uses gasoline.

If she only knew that it has a V8 FSI under the hood that only has to meet emissions standards of a light duty truck ��

LDT4 emissions are ~4x LDV/LDT1 emissions, which is bad, but they aren't VW with emissions cheat enabled bad (~5x-35x).

https://www.dieselnet.com/standards/us/ld_t2.php

VeeDubTDI · Nov 15, 2015

cevans said:
Right, this is the thing that makes me the most upset about this whole thing: the regulations are meaningless.

If cars can only pollute X but trucks can pollute XXX and there is no restriction on trucks sold vs. cars then this isn't a system that encourages emissions reductions.

Being at TDIParts/IDParts now for almost a decade, I cannot count how many long time customers are workmen and use their Sportwagens as "trucks" instead of an F150 etc.

So, in this system, those who choose to get the Sportwagen to save $$ on fuel are punished versus those who choose to buy the truck. Its actually WORSE - due to CAFE standards they need to sell the fuel-efficient cars, and those who purchase the fuel efficient cars are in a sense subsidizing the sales of pickup trucks. The Sportwagens have been labeled as "polluters" and are required to have complicated and expensive emission systems to meet some arbitrary NOx numbers. Gasoline powered trucks, nope.

What kind of system is this? This isn't a democrat vs. republican thing - if the administration is serious about pollution, be serious about it, don't set up a paper swiss cheese system. Otherwise, just get out of the way and stop punishing the wrong people.

Passenger car and light duty truck emissions standards have been aligned for several years, with the exception being CO2 since that is tied directly to fuel consumption. A carbon tax would level the playing field for CO2, although at the expense of great squawking by pickup truck and SUV commuters.

makattack · Nov 16, 2015

I've seen mentioned in other threads about gasoline engines going with higher compression ratios and lean fuel/air ratios, like diesels, which is provides the conditions for NOx to be generated, but here's an interesting thing: Mazda seems to be going towards bringing back the Wankel rotary engine using HCCI as a EV range extender:

From 2013:
http://articles.sae.org/12696/

More recently:
http://www.foxnews.com/leisure/2015/11/16/mazda-rotary-engine-may-lose-its-spark/

tadawson · Nov 16, 2015

The wankel was not a bad concept, they just had fits getting sliding seals in the thing that would hold up. Perhaps the advances in material technologies will help that now . . . Otherwise, a lot of power is a small package, since 3 combustion pulses per rotor per rotation, as opposed to 1/2 per cylinder with pistons, and zero reciprocating mass . . .

- Tim

Are Diesel cleaner than Gas cars?

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