MadSci Network: Engineering

Re: The Electronic car, is it a wise use of our energy resources?

Area: Engineering
Posted By: Matthew Buynoski, Senior Member Technical Staff,Advanced Micro Devices
Date: Mon Oct 6 21:04:07 1997
Area of science: Engineering
ID: 875047825.Eg
The 'electronic car' is a vague term, which could mean anything from a 
computer controlled standard internal combustion engine to a hybrid IC/
electric motor car, to a full battery/electric to a solar powered test

Use of electronics to control the engine of a standard car has made 
possible lower exhaust emissions levels and better fuel economy. In this
case it is a win.

Solar powered cars are presently impractical in my view, and suitable only
for contest test vehicles. Perhaps some solar panels could be added to 
other electric designs as an additional power source, but it is not at this
time worth major development.

The full-battery, electric-motor-only car I have reservations about. It 
certainly pollutes less at the tailpipe, but the overall gain is not so 
certain. Battery manufacture and recycling (they don't last forever) take 
back some of the advantage gained and involve a fair amount of lead 
processing (At least the way things are today, lead-acid is the only viable 
battery. This could change.). Also, the power plant that made the 
electricity does create emissions. Large power plants are more efficient 
than internal combustion engines, and the emissions are probably better 
controlled at a major power plant, where (for instance) it is possible to 
install electrostatic precipitators against particulate emissions. The 
transmission losses of the electricity from plant to auto-charging station 
are a dead loss, although they may not be that large (5%? I'm 
guessing...better have a power engineer deal with that aspect of it). 
However, my main reservation about full-battery electric-only cars is that 
I don't think the public will accept their limited range and capabilities. 
This will mean that most of the design and development resources put into 
these vehicles is likely to be wasted.

Hybrid cars, with a small IC engine running at peak efficiency only to run 
an alternator or  recharge a (much smaller) battery pack and with wheels 
driven by electric motor, seems to me to be the best current engineering 
solution. From what I have read they are almost as low in total emissions 
as full-battery (when the power plant emissions are figured in), avoid the 
weight problems and lead processing problems of full-battery systems, and 
have far fewer limitations as to range. Moreover, they don't require the 
creation of a system of recharging stations; present gas stations can 
continue to be used. This avoids obsolescene of a huge infrastructure in 
our society.

I might add that to really gain the benefit of electric motors, the vehicle
should be set up so that during braking, mechanical motion of the car is
reconverted back into power in the battery or stored into a spinning 
flywheel. This applies to either full-battery or hybrid types. 

Hybrid electric cars strike me as a viable development objective and one 
that is likely to produce a useable product that will be superior to the
standard IC engine car in emissions and fuel economy, and still deliver 
performance adequate to the buying public. 

Scientific American magazine recently published a long article on electric
cars; you should read that for further information and references. I can
not find (Arrrgh!) my copy of that issue, unfortunately, so I can't give 
you the month.

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