Re: [Phys-l] gasoline

[Rick Tarara <rtarara@saintmarys.edu>]

The gasohol at 10% should not be responsible for the large mileage drop. 
While the ethanol does have a lower energy content (70-80% of gasoline as I 
remember), it is only 10% of the mixture.  The actual drop in energy content 
is only about 2% and that drop is compensated by the lower cost of the 
fuel--supposedly!  Now with E85 (85% ethanol) you would expect a 15-20% drop 
in mileage, so E85 (requires special engines) needs to be considerably 
cheaper than gasoline to be worthwhile.  Then there is the whole debate 
about the energy needed to produce the fuel.  For gasoline, the NET output 
is about 80% but for ethanol the numbers go from 40% down to negative 
depending on who you listen to.  25% seems to be the number the government 
is going with, but that ultimately means that the useful energy density of 
ethanol is too low (read that as excessive land use) to be practical as a 
real energy resource.  As a way to reduce dependency on foreign oil or to 
subsidize farmers, it may work just fine, but we are are really can't afford 
the farm land needed to replace our gasoline use with ethanol use.

(I think the 45 mpg for a Prius is pretty much the norm.)

Rick (whose '06 gasoline powered Civic does get 40 mpg for 60 mph highway 
travel, but

***************************
Richard W. Tarara
Professor of Physics
Saint Mary's College
Notre Dame, IN
rtarara@saintmarys.edu
******************************
Free Physics Software
PC & Mac
www.saintmarys.edu/~rtarara/software.html
*******************************
----- Original Message ----- 
From: "Sheron Snyder" <snyders@cablespeed.com>
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Sent: Friday, September 01, 2006 11:01 AM
Subject: Re: [Phys-l] gasoline


> Re: the Insight's 70 MPG report
>
> Is that miles per gallon for the fuel we can purchase today?
>
> I know the quoted mpg in the past was for gasoline not the gasohol (10%
> ethanol) which is pumped today.
> The gas stations are not required to tell us the mixture, so the figures
> quoted may not be actual experience.
>
> We own a Prius.  We watch the mpgs very closely.  The PRE- gasohol mpgs in
> the summer was 62 mpg,  Now we are experiencing 45 to 47 mpg.
>
> This driving is done over the same course with the same driver and the 
> same
> passengers and the same tire inflation and the car is regularly serviced.
>
> Thought some would like the data.
>
> Sheron
> LCC Integrated Sciences
>
> ----- Original Message ----- 
> From: "Rick Tarara" <rtarara@saintmarys.edu>
> To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
> Sent: Friday, September 01, 2006 7:55 AM
> Subject: Re: [Phys-l] gasoline
>
>
> > ----- Original Message ----- 
> > From: "Brian Whatcott" <betwys1@sbcglobal.net>
> >
> >
> > > > In the September 2006 issue of Popular Science, there is an interesting
> > > > article on starting on page 50: "The Race To 100 MPG." A prize of $25
> > > > million will be given to the first group to bring a 100-mpg car to
> > > > market.
> > > > And the race is on! >
> >
> > > In annual fuel economy competitions, vehicles which might loosely be
> > >  called cars make fuel economies in the thousands of MPG on a
> > > flat track,  using any and every fuel reduction technique known.
> >
> > Which is why the competition is 'to bring a 100-mpg car to market.'  I am
> > assuming the vehicle has to carry at least 2 people (4 would be more
> > useful)
> > and of course has to meet all safety regulations.  That makes a big
> > difference between the somewhat meaningless fuel economy competitions 
> > that
> > Brian notes, and something useful for the driving public.  The Honda
> > Insight
> > nominally gets 70 mpg, so it would seem that the goal is not out of 
> > reach,
> > but then again you don't see many Insights driving around -- can be a
> > scary
> > sight to see one surrounded by H2 Hummers!   ;-)
> >
> > Rick
> >
> > ***************************
> > Richard W. Tarara
> > Professor of Physics
> > Saint Mary's College
> > Notre Dame, IN
> > rtarara@saintmarys.edu
> > ******************************
> > Free Physics Software
> > PC & Mac
> > www.saintmarys.edu/~rtarara/software.html
> > *******************************
> >
> > _______________________________________________
> > Forum for Physics Educators
> > Phys-l@carnot.physics.buffalo.edu
> > https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
>
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l