MadSci Network: Engineering
Query:

Re: Do we really need longer-life batteries for electric cars?

Date: Fri Mar 17 07:06:55 2000
Posted By: Lawrence Skarin, Faculty, Electrical Engineering, Monroe Community College, Rochester, New York.
Area of science: Engineering
ID: 951726323.Eg
Message:

Your attitude is commendable, but I'm afraid what is "well enough" for you 
will not suit the average driver.  Drivers have "expectations."  One is at 
least 500 kilometers between stops for energy.  A second is acceleration 
adequate to get onto high-speed thruways safely.  A third is enough 
carrying capacity.  And once these specifications are met, drivers never 
like to "go backwards."

With gasoline having an energy density of 14 kilowatt-hours/kilogram, and 
a lead-acid battery having about 0.04 kilowatt-hours/kilogram, it is clear 
batteries have a disadvantage in the amount of "dead weight" and "dead 
volume" a 500 kilometer car would carry.  A site that elaborates on this 
is:  http://whyfiles.org/005electcar/4.html

There is much written on what technologies automobiles may be moving 
toward.  Hybrid (gasoline/electric) vehicles like the Honda Insight or the 
Toyota Prius promise excellent fuel economy and low pollution offset by 
higher initial cost.  And both cars meet the "expectations" I mentioned 
previously.
  
The Economist magazine, in a recent article on these hybrids, suggested 
these vehicles may be only transitional because something "better" is 
coming  the fuel cell.  Not an ordinary fuel cell using hard-to-handle 
hydrogen    this one's based on liquid fuel (like gasoline and alcohol) 
with a "reforming" technology doing the hydrogen extraction.   

Under the battery-power electric car scenario, the current automobile 
energy distribution system using pipelines, rail, tanker boats and trucks 
would have to be scrapped.  And (here's the fun part) car makers would 
have to standardize the battery packs in order to make for efficiency in 
the swapping you suggest.

But a reforming fuel cell electric car would use gasoline or alcohol.  And 
the existing energy distribution network could be used with modest 
modification.  Here's an article optimistic on the technology:
 http://www.wired.com/wired/5.10/hydrogen.html

I make no bets myself.  But whatever we move toward has to meet some 
economic criteria and political pressures from the parties concerned and I 
hope will address pollution and conservation concerns.

Larry Skarin


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