[Vwdiesel] negative aspects of burning water

[Terry Briggs]

Considering the truck I'm speaking of gets 18 mpg cross country {that 
means off road cross country} and weighs over 15000lbs, I'd say that's 
a pretty significant advantage. Now apply the same technology to a car 
that weighs in at around 3000 lbs, and you can just about figure the 
fuel mileage increase, yep, pretty darn easy to imagine.
On Sep 18, 2007, at 2:54 AM, James Hansen wrote:

> Terry Briggs wrote:
>> the advantage of a diesel-electric hybrid, thats an easy one, you can
>> use a much less powerful diesel engine and still have the torque of an
>> engine 3 times the size of what you are using and still get great
>> mileage {comparatively}. It's being used now for that very reason
>>
>
> Is it really an easy one?
>
> Have you considered the efficiency losses Terry?  If you can't do 
> 100mpg
> with a hybrid, it really isn't worth the extra energy footprint to make
> assemble and carry around all the stuff to have the hybrid.  A lupo 
> does
> in the 90's with a simple 3 cylinder tdi, so a diesel hybrid better do
> more than that, or you're just chasing your tail.
>
> Diesels only use as much fuel as needed to make the power required at
> the time, unlike a gas engine.  To expound on that, cause it seems to 
> be
> falling on deaf ears at present... all the air going through a gas
> engine has to be at stoich mix fuel to air ratio, or the motor grenades
> eventually.  Diesels have no such constraint, so they will run very
> efficiently throughout the range of power requirements and rpm.  If you
> run a diesel at low power requirements, you essentially HAVE a much 
> less
> powerful motor, until you stomp on it- if you design a car to need 10hp
> at 60mph, your diesel motor will be making 10hp, and using a
> corresponding amount of fuel. The only loss in a diesel over a gas is
> the pumping losses of moving the unthrottled air through the motor.
>    A gas motor cannot run at much less than stoich mix, hence the
> tremendous gains in efficiency in running it at a constant speed at max
> efficiency to generate power a la hybrid.
>
> Trick is, each step in the hybrid train has efficiency losses.
> Generation, storage, regulation, transmission, usage, do not have 100%
> efficiency.
>
> I'm curious if anyone has run the numbers in this.  Roger, you're a
> clever fellow.  If you're following along, do you have any top of the
> head guestimates on losses in each of the steps a hybrid goes through
> with it's energy production, regulation, storage, sharge control, etc?
>
> thanks
> -james
>
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