[SGVLUG] OT: Hybrid efficiency (was:New Linux Lug)

[David Lawyer]

On Fri, Mar 03, 2006 at 04:43:32PM -0800, Dustin Laurence wrote:
> On Fri, Mar 03, 2006 at 04:02:44PM -0800, David Lawyer wrote:
> 
> > I'm back.  From what I recall, Dustin didn't study good "Brake
> > Specific Fuel Consumption Maps", nor plot load lines on them.  If he
> > had done this, he would understand what I'm talking about and not have
> > raised all the objections he did.
> 
> No, the problem is that no one in the world, except for you, wants to do
> what you are doing 
Well, I found this on the Internet:

Pulse And Glide - Getting Maximum Fuel Economy In A Prius

   From [53]Eric Powers,
   Your Guide to [54]Hybrid Cars.
   FREE Newsletter. [55]Sign Up Now!

A Special Technique For Certain Hybrid Cars

   On August 7, 2005 five men took an unmodified Prius nearly 1400 miles
   on a single 12.87 gallon tank of gas. That's 109 mpg! They did it by
   using a technique called "Pulse and Glide".

   General Notes About Pulse And Glide
   The Pulse and Glide technique alternates between periods of Pulsing and
   periods of Gliding while trying to avoid using the Prius' large hybrid
   car battery.

"http://hybridcars.about.com/od/ownership/a/pulseandglide.htm">Pulse And Glide - Getting Maximum Fuel Economy In A Prius

So you see the way to save energy in the Prius is to use it like they
did as a non-hybrid without use of the battery ;-).

> (anyone can get better mileage at highway speeds
> simply by slowing down to your average speed and driving steadily),

See www.fueleconomy.gov (US DOE).  The curve shows that 55 mi/hr gives
the highest fuel economy for reasons I already explained.  Now you
would save a lot more energy using "pulse and glide".  It's kind of
tragic that as you speed up, your engine becomes more efficient
but if the engine slowed down and you increased torque (by
flooring the accelerator), it would be even more efficient.  But cars
don't have a high enough gear to utilize this.

> and  that you have some erroneous ideas about certain areas of physics.  I
> don't feel like trying to figure out which parts are misunderstandings
> of mechanics and which parts are simply perverse terminology, but both
> are present (for example, by definition coasting can't be a method of
> energy *recovery,* and your actual arguments amount to a claim is that
> it is a method of energy *conservation*--these two terms do *not* mean
> the same thing).

I thought I already explained this.  Coasting does recover the kinetic
energy by using it at 100% efficiency of conversion to power the car
(by overcoming rolling resistance).  Its something like storing
the car's kinetic energy in flywheels and then using the flywheel
energy to propel the car.  But if the flywheel uses and electric
motor/generator to exchange energy, it recovers only say 70% of the
kinetic energy (better than batteries).  So when you coast, the car
loses kinetic energy due to vehicle resistance and all of this kinetic
energy lost is used to propel the car, so it's recovered at 100%
efficiency and not wasted.  There is no way to avoid vehicle
resistance in a given situation and thus it's useful work.  
If it's a waste of energy then all the fuel used in auto engines is
wasted energy (except for the energy used for car audio).  You stated
that the energy used in overcoming vehicle resistance is turned into
heat.  Well then, isn't the car audio energy turned into heat also?
:-)
> 
> You also ignored the very real objections that your driving method is
> probably not safe, not clearly legal to me (it is guaranteed to be
> illegal in every juridiction I've heard of for any vehicle with enough
> torque to break a driving wheel free, "demonstration of speed" I think
> is the term, or perhaps "drag racing" when done from a stoplight), and
> even if legal vulnerable to (deserved, IMO) harassment from police who
> are likely to suspect you of driving while intoxicated, sleepy, or
> carelessly.  Nor does it scale--a freeway full of people driving that
> way would not only be unsafe but would have a much lower traffic
> capacity, so the very last thing in the world any urban planner wants is
> to encourage that kind of driving.
Perhaps lower capacity would discourged travel and thus save energy.
Also as gasoline prices increase, travel is likely to decrease so the
lower traffic capacity will not be restrictive.
> 
> Without addressing the latter problems it wouldn't even matter if you
> were right.
> 
> Dustin
I addressed it by proposing change.  If I'm right, shouldn't we change
the laws?

Actually the major problem as I see it is Jevon's Law (1865):
Increasing energy efficiency only results in using more energy.  Hence
it's counterproductive.  At first glance, it seems absurd, but history
is on it's side.  For example, Jevon was right about coal, because
increasing efficiency of steam engines, rather than saving energy in
the 19th century, resulted in much more coal being used.

In 1900 trains and streetcars (no autos) were only 1/5 as efficiency
as our travel today in mostly autos and airplane.  But we now use 40
times as much fuel.  Government mandates to improve auto efficiency
only resulted in more fuel being used.  So what's the solution?  I
think it's mainly less travel and lower population.  Thus I'm
supporting the forming of a LUG in Azusa (for purposes of less
travel), which is the "On Topic" which led us into this "Off Topic"
discussion.

			David Lawyer