Diesel cleaner than Natural Gas

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troy_heagy

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Feb 23, 2001
I almost bought a Civic CNG car... now I'm glad I didn't!

Figures... the EPA claims to know what is "clean" but this proves that they have no idea. They push CNG as the cleanest car you can buy (next to electric), but now we find out the TRUTH.

Troy
 
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weedeater

Top Post Dawg
Joined
Mar 17, 2001
Location
Reston, VA
TDI
Jetta, 2001, Baltic Green
Interesting. Last year, DC decided to replace part of its fleet of diesel busses with CNG busses because they were 'less polluting' than the diesel busses they would have bought. Never mind the fact that the CNG busses cost more. Never mind the fact that they had to pay hundreds of thousands of dollars to build the specialized CNG fueling and engine servicing facilities.

Your tax dollars at work...
 
M

mickey

Guest
And troy's march toward Realistic Environmentalism marches on!

-mickey
 
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Manny

Active member
Joined
Apr 14, 2002
Location
Ohio, USA
Technology for CNG still way behind, big problems and extra expense keep it from being viable for most applications. Only way its successful in city bus fleets is due to very heavy subsidation by gov't. Buses themselves are extrordianarily expensive, have far more maintenance requirements and don't have the reliability or longevity of diesels. Our local transit authority went with them, built the fueling system and got rid of them after just 2 years when it became evident that they would bankrupt their budget to keep them running after warranty expired. Once the gov't money goes away you can't afford them.
Manny
 
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henryp

Veteran Member
Joined
Oct 31, 1999
Location
The Great White North
TDI
1998 NB TDI
I considered converting my ride to Natural Gas a number of years ago. The big draw was the convenience of home fuelling. The gas company has a nice compact compressor that can fill up your car overnight as it sits in the driveway.

Now - I have a couple of nice home heating fuel tanks for my oil (converted to gas) furnace that would be great for storing some nice Biodiesel (BD100 of course). Home fuelling is an awesome concept.


henry
 
T

troy_heagy

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Joined
Feb 23, 2001
Neighbor: "Nice oil burner."
Me: "No... it's not oil. It's 100% soybean-derived biodiesel. :)"

I wonder if Natural Gas electrical plants *also* emit large amounts of toxic chemicals and soot? If environmentalists were wrong about "clean" natural gas buses, they are probably wrong about "clean" natural gas plants too!

Grrrr....

Troy
 
D

Diesel-Bear

Veteran Member
Joined
Dec 25, 2000
Location
Denmark
Before You all get to hysterical about our much beloved TDIs:

Quote from the article:
The CARB study says that diesel engines WITH soot filters emit fewer and less-toxic compounds than "clean" CNG engines.
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<font size="2" face="Verdana, Helvetica, sans-serif">On last count NO TDI-vehicles had soot-filters... So there


But TDI holds plenty of other advantages over most any CNG car. Safety not being the least. Try to imagine what will happen if Your CNG-car is rear-ended some evening, and the offender is unable to turn off his smashed headlights.
 
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MITBeta

Top Post Dawg
Joined
Feb 24, 2001
Location
Boston's Metro South-West
TDI
2001 Jetta TDI, 2004 Sprinter CDI Passenger (Mid/High), former: 1996 Passat TDI Variant
I wonder if Natural Gas electrical plants *also* emit large amounts of toxic chemicals and soot? If environmentalists were wrong about "clean" natural gas buses, they are probably wrong about "clean" natural gas plants too!
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<font size="2" face="Verdana, Helvetica, sans-serif">Just like our TDIs, Natural Gas plants are VERY efficient. Combined cycle gas plants easily achieve thermal efficiencies of 70% or more. So while they may put out some dirties, it's unlikely that they are TWICE as dirty as a 30% efficient plant of any kind (expect nuclear, but that's a different story...).

Try to imagine what will happen if Your CNG-car is rear-ended some evening, and the offender is unable to turn off his smashed headlights.
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<font size="2" face="Verdana, Helvetica, sans-serif">I spoke with some engineers from Cummins who were demonstrating their 7.3L 6 cylinder turbocharged CNG engine at an alternative fuel vehicle exposition. The fuel tanks were made of kevlar, with no "sparking" materials. It takes an armor piercing bullet to break through the kevlar, and if that happens, the tank has two defense mechanisms: 1. the high pressure tank in a well ventilated area makes it very hard to keep a flame lit. The speed of the gas exiting the container literally blows out any flames. 2. If a flame does start, the tank is equipped with a large venting device that vents the contents of the tank up and away from the vehicle.

Given this, I don't think CNG is any more dangerous than gasoline. Probably more dangerous than diesel still, but the safety issues have been seriously blown out of proportion.

On last count NO TDI-vehicles had soot-filters... So there
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<font size="2" face="Verdana, Helvetica, sans-serif">Most CNG engines today are designed to fit into buses, and MANY diesel buses are being retro-fit with NOx and Particulate traps AND being run on ULSD. The MBTA in Boston announced last week that its whole fleet is now running on ULSD and over the course of the next few years the fleet will be fitted with particulate and NOx traps.

When ULSD is avialable, diesel cars will also get these traps. So CNG might be slightly cleaner today, but won't be in the long run, especially if fleets start using biodiesel as well.
 
D

Diesel-Bear

Veteran Member
Joined
Dec 25, 2000
Location
Denmark
Originally posted by MITBeta:
Most CNG engines today are designed to fit into buses, and MANY diesel buses are being retro-fit with NOx and Particulate traps AND being run on ULSD. The MBTA in Boston announced last week that its whole fleet is now running on ULSD and over the course of the next few years the fleet will be fitted with particulate and NOx traps.

When ULSD is avialable, diesel cars will also get these traps. So CNG might be slightly cleaner today, but won't be in the long run, especially if fleets start using biodiesel as well.
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<font size="2" face="Verdana, Helvetica, sans-serif">Let's all hope You're right on this note. Experience within he EU is so far, that even though we already have ULSD, VW has chosen not to fit them to their TDIs.

Peugeot ARE fitting then to Their more expensive CDIs. But even so, Citroën is still on the fence about this (all though they are Using the same PSA diesel engines).

We probably won't see soot filters on other diesels before it is a mandatory by law.

Still: Until soot filters have become mandatory, I would much more prefer to breathe the exhaust of CNG cars than TDIs.

On a third note: CNG-prduction in large scale uses a fossil fuel. In the TDI, You are able to run on 100 % bio-fuel. Here in Denmark, we have seen large scaled test-installations that was supposed to produce Propane from garbage. Only, it turns out, that the total amount of energy You could gain this way was much has lower than if You burn the garbage directly (and use the heat to warm houses in the region).

There never seem to be any one answer to our energy- and pollution-problems. But it *have* been proven time and time again, that gas (petrol) is the least efficient engine fuel.

[ April 28, 2002, 11:55: Message edited by: Diesel-Bear ]
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T

troy_heagy

BANNED
Joined
Feb 23, 2001
Originally posted by Diesel-Bear:
Let's all hope You're right on this note. Experience within he EU is so far, that even though we already have ULSD, VW has chosen not to fit them to their TDIs.

Still: Until soot filters have become mandatory, I would much more prefer to breathe the exhaust of CNG cars than TDIs.
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<font size="2" face="Verdana, Helvetica, sans-serif">(1) If VW doesn't add PM traps, Ford will. They are still planning to introduce a ULEV-2 diesel truck in 2004-5.

(2) CNG emits soot too. (read the article)
 
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Luis

Veteran Member
Joined
Aug 23, 2000
Location
México City, D.F.
Just a story from someplace else in the world...

I live in Mexico City, we have an average altitude above sea level of 6,700 ft. We get LOTS of smog from diesel burning buses. It has become a major concern and the EPA equivalent SMADF is thinking of banning diesel powered trucks and "stimulate" the use of CNG powered transports instead.

As a TDI owner, I do contribute as well to my city's smog level.

I still believe that diesel engines are much more thermically efficient than CNG, but definitely a turbodiesel is not the best option on a stop and go situation, heavy traffic, and very high altitude.

I would say a supercharged diesel with a 20 psig (notice psig instead of psi) idling charge pressure is a must around here....coupled with an efficient cat converter, of course... is this arrangement any common at all?

Does anyone from this TDI club live in a high altitude city as well?

Luis
 
T

troy_heagy

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Joined
Feb 23, 2001
Salt Lake City (temporarily) I believe it's 5000 feet here and during the winter we had smog inversions that caused skin rashes.

Troy
 
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BillW

Veteran Member
Joined
Jan 22, 2001
Location
SLC, UT, USA
Salt Lake City is about 4,300 feet above sea level. I believe Denver, Colorado is about 5,000 feet above sea level. If you go to Park City or Heber, Utah they are about 7,000 to 8,000 feet above sea level.
 
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