Regarding Bart Jackson’s December 10 Survival Guide story, “Making the Case for Electric Cars:”

Whoever believes, as many people currently do, that storage batteries are a prominent part of the solution to energy independence and global warming should probably read the two articles I had passed on to me recently which highlight the cost, scarcity, and geopolitical inconvenience of the materials now believed to be best for high-performance batteries. The URLs are given below:

http://spectrum.ieee.org/sep07/5490/2

http://www.meridian-int-res.com/Projects/The_Zinc_Air_Solution.pdf

As far as any electric vehicles are concerned, whether powered by batteries or fuel cells (or even hybrids using ultracapacitors) these articles raise a separate set of questions as to the cost, scarcity, and availability of the materials needed for electric-traction motors which can be reversibly used as generators, for regenerative braking and energy recapture.

The only motor I am aware of (I used to be a professional electronic engineer) that can perform such a dual function and which has no slip rings or brushes or commutator, and hence no parts intrinsically subject to wearing out, uses a permanent magnet rotor. The best permanent magnets (last I heard) were made from an alloy generically known as alnico, which originally stood for aluminum, nickel, cobalt. Its predominant ingredient is iron — apparently that goes without saying — but it may also include titanium and copper; the fractional content of the materials other than iron can be quite large, at least 10 percent and upward.

The stationary parts of these motors also will use plenty of ferromagnetic material, plus equal or greater amounts of copper. I have seen no analysis of how these factors would add up — nor would I believe anyone’s projections of how much any scarce material might cost if the world started to depend much more heavily on it than it has up to now — but along with the materials concerns raised regarding batteries in the two articles identified above, there are almost certainly parallel concerns as to the materials used in high-endurance dual-use electric motor-generators.

Mr. Jackson’s concluding paragraphs talk about the Mini E [the all-electric Mini-Cooper being developed by BMW] as though all the problems were solved, or soon to be solved, and appear to accept as established fact that batteries will replace gasoline, and sooner rather than later.

Not likely. The performance batteries are now capable of is quite near the absolute limit of their basic principles — they’ve been under development and study for approximately 240 years, and “we” have been through these flurries of fervor several times in the past. The Mini E is a zippy upscale enclosed golf cart, with room for two people and three grocery bags if the people are small, and it may very well be, as he implies, the ultimate expression of the art.

Its chief designer, I am reliably told by a well-known automotive journalist, is the same guy — American — who “did” the GM EV-1 15 years ago; he’s using everything he learned then and everything anyone else has come up with in the past 15 years, and this is the best that can be done. Its battery weighs 572 pounds, presumably mostly in materials which are subject to the supply constraints discussed in the two Internet postings.

There are about 200 million personal-use vehicles in the U. S. alone; the rest of the world, as time goes on — present-day economic catastrophe permitting — will eventually have several times as many as we now do. As I recall the articles’ conclusions about materials availability, a billion or so all-electric variants of the Mini E will never be remotely possible. Mr. Jackson’s “case closed” final comment may be appropriate, but not with the verdict he had in mind.

John Strother

Grover Avenue, Princeton

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