[Vwdiesel] Honda Diesel

[Roger Brown]

I recall reading a report a few years ago stating that "cleaning up" diesel engines may 
have double negative impact on climate change.  The older engines/fuel that burned with 
more visible soot output put that soot in the air and that actually reduced heat gain to 
the atmosphere.  So now you refine the fuel more to clean it up (more refining = more 
energy input = more CO2 output) then it takes more of that same fuel in a given engine to 
produce the same output (your 12% - 20% increase) so more fuel burned = more CO2 output. 
And then you have reduced the soot, which looks good to the average citizen, but that soot 
was helping reduce temperature rise.  And it is the fuel efficiency of the highest 
efficiency (diesel) engines that is being reduced.

It is kind of like the cholesterol story, you have good cholesterol (HDL) and bad 
cholesterol (LDL, etc.).  Now you have reduced the good cholesterol (soot) and raised the 
bad cholesterol (CO2) and what is the gain?  Seems if that were a patient, that patient's 
doctor would be doing something to reverse that trend.


On 1/31/2012 10:31 AM, James Hansen wrote:
> Oh, man, I know.  Diesel makes the world go round, but gas drives those that
> think the world revolves around them.
>
> To an end user (me for instance), it would seem that great pains have been
> taken to improve air quality almost solely at the sacrifice of efficiency...
> to the tune of about a 12 TO 25% increase in fuel usage moving from tier 2
> to tier 3 compliance in ag engines.  Pretty much the same for other on and
> off road users with a wide variability in how the increased costs get passed
> on.  Now that we are in tier 4 transitional compliance, different technology
> is being used (urea) which should bring fuel efficiency back up... maybe for
> some anyway (not JD).  But no matter how you look at it, efficiency is
> certainly not high on the want list of the rule makers.  Kind of like
> natural selection, if you don't select for it, you don't get it, and nobody
> in the north american engine market has been big on efficiency because it
> all hangs on nitrogen emissions. Some players have a lot of European
> exposure, which influences their engine design quite a bit it would seem.
> (fiat group- case, NH, etc)
>
> Reasons vary, but mainly it was using EGR.  It's like we are now replaying
> the "smog rules" engines cars used in the 1970's in offroad engines.  They
> use EGR to keep the combustion chamber cool to not make NOX compounds, and
> surprise surprise, you have to use more fuel to get the same power. I
> distinctly remember the parents 1978 bronco that made a whopping 8mpg
> IMPERIAL right out of the box. You could quite easily confuse the
> speedometer with the gauge for the enormous fuel tank, both moved in
> concert, but different directions.
>
> At least those that are now using urea cat in tier 4 engines are able to
> bump timing and durations with high boost to get really hot combustion, hot
> combustion chambers make more efficient power, it makes the particle trap
> work better too, then fix the nox with a urea cat.  Overall efficiency is
> much much higher.  Guys that I know that have bought the 350K new tractor
> are quite happy with them- they HAD to get rid of the fuel guzzler tier 3
> junk that it replaced.  A big acre farmer can make a tractor payment on the
> difference in fuel use between tier 3 and 4 transitional engines.
>
> I wonder Travis, since the EPA has been used as a trade manipulator for so
> long with air quality being the saw, if they would know what is good for the
> environment even if it jumped up and bit them in the ass. Personally, I kind
> of doubt it, it's still more enviropolitics than good intelligent use of
> resources in some kind of sustainable manner.
> -james
>
> -----Original Message-----
> From: vwdiesel-bounces at vwfans.com [mailto:vwdiesel-bounces at vwfans.com] On
> Behalf Of Travis Gottschalk
> Sent: January-31-12 11:42 AM
> To: vwdiesel at vwfans.com
> Subject: Re: [Vwdiesel] Honda Diesel
>
>
> You mean all the "verage fuel efficiency decreasing in ag equipment -
> various politico-environmental reasons" isn't good for the environment? I
> always wondered how is it that they seem to think that more cleaner (but not
> completely clean) air/fuel is better then a little "dirty" air. Isn't being
> truely "green" just making things more efficient? It has to be self
> sustaining. Also as to the fuel in the US-just because there isn't a lot of
> cars that burn diesel there is plenty of ships, trains, Heavy equipment
> (mines, road construction) and over the road trucks. There is more Diesel in
> the US then you think and the funny thing is because it is more effecient
> then gas. But the individual consumer still chooses gas.
>
> 	 	   		
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-- 

   Roger