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Carnegie-Mellon Study on Electric Cars Debunked

by Robert W. Benson, 
Professor of Law, Loyola Law School, Los Angeles
rbenson@icg.apc.org   Tel. 213/736-1094


The Christian Science Monitor of Friday, June 9, 1995 carries 
my article challenging the Carnegie-Mellon study on electric 
cars (Lester B. Lave, Chris T. Hendrickson, Francis C. 
McMichael, "Environmental Implications of Electric Cars," 
Science  magazine, May 19, 1995 (vol. 268, p. 993).  

These are the bases of my challenge: 

%   Carnegie-Mellon's connections to the auto and oil
industries for this research raise questions about 
ethics and bias. 

% The study lacks intellectual integrity in drawing the 
"conclusion" that electric cars "do not deliver the promised 
environmental benefits" without making any attempt to 
calculate the costs and benefits.

%  The authors make mistakes such as confusing kilograms for 
pounds (Table 1, row 1) and miscalculating the weight of the 
GM ImpactUs battery pack at 500 kg instead of 420 kg.

% They commit at least five major methodological errors in 
arriving at their statement that, "A 1998 model electric car 
is estimated to release 60 times more lead per kilometer of 
use relative to a comparable car burning leaded gasoline."  I 
was not able to describe the five errors in the Christian 
Science Monitor piece.  I have put these together from 
analyses done by David Goldstein of Program Development 
Associates, by the Union of Concerned Scientists, and by the 
EPA.   This is my synthesis:  

1.  The efficiency of available battery technology is grossly 
underestimated by including very outdated technology, by 
including heavy van data in an article devoted to "cars," by 
miscalculations, by incorrect estimates of the cycle life of 
current batteries, and by ignoring newer technology that is 
now being marketed. 

2.  The "60 times more lead" figure is calculated on the 
basis of virgin-mined lead, when in fact about 95 to 98% of 
lead batteries are recycled and very few are manufactured 
from virgin lead.

3.  The "60 times more lead" figure is compared to a car 
burning leaded gasoline, but the authors artificially reduce 
the gasoline car's lead releases by 25% for lead "retained in 
the engine and exhaust of the car."    This is improper since 
that lead too is ultimately released to the environment when 
the car is scrapped. 

4.  The "60 times more lead" figure underestimates pollution 
from leaded gasoline by omitting contamination from the 
mining and processing of lead for the gasoline, while it is 
the mining and processing alone that the authors point to as 
the source of danger from lead-acid batteries. 

5.  Selection of a Geo Metro getting 45 miles per gallon for 
comparison underestimates by more than 100% the amount of 
lead we would have from actually running our cars today on 
leaded gasoline since today's fleet average is about 22 mpg. 
It was even less in the 1970s when leaded gasoline was in 
full use.  The authors say a Geo Metro is  "comparable" to an 
electric car because of size and weight. They are wrong, 
since a Geo is much lighter.  But more to the point, it is 
simply not logically relevant to look to a Geo as the 
standard of comparison.  The thing we want to know is whether 
electric cars are putting more lead into the environment than 
the old cars of the 1970s did when they ran on leaded gas, or 
more than today's average car getting 22 mpg would if it ran 
on leaded gas.  It is hard to resist the conclusion that the 
authors chose the Geo in order to get a figure showing the 
smallest possible amount of pollution from leaded gasoline, 
so that the electric car batteries would look worse in 
comparison. 

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