veedub_tdi
Well-known member
- Joined
- Jun 29, 2001
- Location
- Scarborough, Ontario
<font size="2" face="Verdana, Helvetica, sans-serif">On last count NO TDI-vehicles had soot-filters... So thereQuote from the article:
The CARB study says that diesel engines WITH soot filters emit fewer and less-toxic compounds than "clean" CNG engines.
<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...).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!
<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.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.
<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.On last count NO TDI-vehicles had soot-filters... So there
Originally posted by MITBeta:
<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.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.
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 ]
<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.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.