Diesel vs Gas environmental impact - Fuelly Forums

Android Users - Coming Soon! - Migrating from aCar 4.8 to 5.0

Reply
 
Thread Tools Display Modes
 
Old 09-18-2007, 01:33 PM   #1
Registered Member
 
Join Date: Jan 2007
Posts: 81
Country: United States
Diesel vs Gas environmental impact

I don't want to start a debate about which is the overall cleaner fuel, because that is a huge question with many different factors involved. Suffice to say that diesel advocates often point to reduced CO2 when they suggest that diesel is ultimately the cleaner fuel. Much of their argument, I believe, is based on the inherently better fuel efficiency of the compression ignition engine.

My question concerns the btu content of the two fuels. Diesel has about 13-14% higher btu content per gallon, which is why comparing the efficiency of spark ignition vs compression ignition based on mpg is misleading. So is the claim that diesel is cleaner based on better fuel economy likewise exaggerated? If diesel has 13-14% more btus per gallon, does it emit that much more CO2 per gallon burned? If this is true, then a diesel vehicle would have to get 13-14% better fuel economy than a gasser in order just to have the same CO2 emissions. Or does diesel actually emit less CO2 per gallon (or even per btu)?

Also, how much energy and crude oil goes into producing the two fuels. Again, I know this is a complicated question because diesel is a by product of refining gasoline, so essentially you can't have one without the other I suppose, but which has the greater environmental impact in getting to the pump, if that can be measured?
__________________

__________________
northboundtrain is offline   Reply With Quote
Old 09-18-2007, 01:38 PM   #2
*shrug*
 
Join Date: Sep 2005
Posts: 6,195
Country: United States
Diesel does emit more CO2 per gallon burned, I forget how much, but it can be looked up easily.

I don't know about production though.
__________________

SVOboy is offline   Reply With Quote
Old 09-18-2007, 03:01 PM   #3
Registered Member
 
omgwtfbyobbq's Avatar
 
Join Date: Jul 2006
Posts: 1,516
Country: United States
I think the increase in Carbon is proportional to the difference in energy content, but offload efficiency is much better for diesel drivetrains, so there's also an improvement in thermodynamic efficiency during low power use. For instance, a 05 diesel and gasoline drivetrain in the same car result in 24mpg and 35mpg respectively, with a correction for energy content. Over the new EPA cycle, the diesel is nearly one and a half times more efficient than the gasser, in the same car. The more efficient the car is, the more pronounced this difference can be. At high load, the difference in efficiency is minimal, so if someone's commute consists of 90% highway at 70mph, there won't be a huge difference between diesel and gas. Otoh, if they can cruise to work in top gear on 40mph roads, there will be a much larger difference, maybe even a relative doubling in mileage.
__________________
Quote:
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
omgwtfbyobbq is offline   Reply With Quote
Old 09-18-2007, 03:11 PM   #4
Registered Member
 
omgwtfbyobbq's Avatar
 
Join Date: Jul 2006
Posts: 1,516
Country: United States
Ya really!
__________________
Quote:
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
omgwtfbyobbq is offline   Reply With Quote
Old 09-18-2007, 03:13 PM   #5
*shrug*
 
Join Date: Sep 2005
Posts: 6,195
Country: United States
But there can be so many differences there besides fuel, like weight, gearing, power output, styling packages, blah blah blah!
SVOboy is offline   Reply With Quote
Old 09-18-2007, 03:19 PM   #6
Registered Member
 
omgwtfbyobbq's Avatar
 
Join Date: Jul 2006
Posts: 1,516
Country: United States
Inverse respectively.
__________________
Quote:
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
omgwtfbyobbq is offline   Reply With Quote
Old 09-18-2007, 03:34 PM   #7
Registered Member
 
omgwtfbyobbq's Avatar
 
Join Date: Jul 2006
Posts: 1,516
Country: United States
Quote:
Originally Posted by SVOboy View Post
But there can be so many differences there besides fuel, like weight, gearing, power output, styling packages, blah blah blah!
Not really. At least not for the comparison I used.
__________________
Quote:
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
omgwtfbyobbq is offline   Reply With Quote
Old 09-18-2007, 03:35 PM   #8
*shrug*
 
Join Date: Sep 2005
Posts: 6,195
Country: United States
List the models, punk.
SVOboy is offline   Reply With Quote
Old 09-18-2007, 03:44 PM   #9
Registered Member
 
omgwtfbyobbq's Avatar
 
Join Date: Jul 2006
Posts: 1,516
Country: United States
Same trim level, 115hp gasoline engine compared to 100hp diesel engine. Diesel powered car weighs 2989, gasoline powered car weighs 2743. Manual transmission ratios are
Gasoline-3.300 1.944 1.308 1.029 0.837 (3.938)
Diesel- 3.778 2.118 1.360 0.971 0.756 (3.389)
__________________
Quote:
Originally Posted by FormulaTwo
I think if i could get that type of FE i would have no problem driving a dildo shaped car.
omgwtfbyobbq is offline   Reply With Quote
Old 09-18-2007, 03:48 PM   #10
*shrug*
 
Join Date: Sep 2005
Posts: 6,195
Country: United States
Jetta?
__________________

SVOboy is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Server Time ynpmoose Fuelly Web Support and Community News 2 12-20-2013 12:53 PM
Quick release windshield wiper ideas? MetroMPG Aerodynamics 30 12-10-2006 07:02 AM
PepsiCo Connections? SVOboy General Discussion (Off-Topic) 3 10-12-2006 05:52 PM
An American Perspective on Driving in Canada rh77 General Discussion (Off-Topic) 28 03-24-2006 10:42 PM
"active" aero grille slats on 06 civic concept MetroMPG General Fuel Topics 21 01-03-2006 01:02 PM

Powered by vBadvanced CMPS v3.2.3


All times are GMT -8. The time now is 02:00 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.