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All the articles that I have read about plug-in electric cars ignore the cost of electricity to charge the on-board battery ["Take This Car and Plug It," News, July Could it be that in some areas where electricity costs US 15 cents per kilowatthour, the operating cost of an efficient gasoline-powered car may be less per mile, even at $2.50 per gallon of gas?
Thomas Deutsch
IEEE Life Member
Hartsdale, N.Y.
The article implicitly assumes that energy for "plugging in the car" will be limitless and nonpolluting. However, in reality it will come from augmenting the electric power grid, which generates most of its electricity with petroleum and other fossil fuels, thus resulting in the use of more petroleum. Because both the car engine and the power plants operate at similar efficiencies, the net gain is zero.
Ivan Bekey
IEEE Member
Annandale, Va.
I would like very much to see a comparison of the fuel efficiency of running a car on gasoline alone, on battery-stored electricity from the grid, and at various points along the spectrum of hybrid-electric technology. The comparison should consider all environmental and societal costs, including resources used in manufacturing the car, environmental effects of centrally generating the electric power the hybrid car takes from the grid, and environmental costs of disposing of its components when the car wears out.
Rick Thomas
IEEE Member
Warren, N.J.
The editor replies: Comparing hybrids on a system basis with vehicles powered by internal combustion engines and alternative fuels is immensely complicated. In an extreme case, suppose a hybrid in the United States obtained all its energy from the electric grid; there would be no reduction in greenhouse gases. This is because roughly half the energy would come from coal, and burning coal produces about twice as much carbon dioxide per unit of energy as oil combustion. But oil imports, for that car, would of course fall 100 percent.
If, more realistically, the car ran on a combination of electricity from the grid and alternative fuels from crops, both greenhouse gases and oil imports would be reduced. Fuels from crops are carbon-neutral—carbon dioxide emitted in combustion is taken from the atmosphere when the crop is grown. For every gallon of imported oil the biofuel replaced, there would be a 100 percent reduction in greenhouse gases.
Accordingly, any assessment of hybrid-electric and gasoline-powered cars in terms of oil and carbon dioxide savings depends on what combination of electricity, ethanol, and gasoline an average hybrid would likely use. For previous discussion of this subject in IEEE Spectrum, see "Hybrid Vehicles Are Worth It!" [May 2001
There is no need to resort to Alan Turing's computer and Alonzo Church's lambda calculus to argue that a line cannot be drawn between software and mathematical expression [Invention, July This is obvious.
Unlike copyright, which protects the concrete expression of an idea, such as a program's source code, patents grant a monopoly on the very idea, regardless of the terms or language used to express it. If you look for the idea behind a piece of software or a program, you end up with an algorithm—that is, mathematics. Thus, using patents to establish intellectual property rights on software boils down to society's granting a 20-year monopoly on the use of mathematical algorithms. And as long as investors perceive specific algorithms as market differentiators, they will push for software patents. Whether that makes for the common good is another story.
Richard Sietmann
IEEE Member
Berlin
I enjoyed your June issue on China but was surprised by your conventional thinking on intellectual property (IP). A college student is mentioned who downloads a pirated Windows operating system because a legal copy would cost him a semester's tuition. This seems like an intelligent decision to me—few in the United States would pay a semester's tuition for a Windows OS. It sounds overpriced for that market.
In the article about electric bicycles, a manager says he responds to IP infringement by innovating more to stay ahead. As IEEE Spectrum has reported, U.S. companies patent increasingly ridiculous items and seek revenues by suing others for infringement, rather than by innovating. Perhaps our assumptions about the usefulness of IP patent protection don't make sense anymore. Spectrum usually thinks out of the box; I hope you can lead us to a new paradigm if one is needed.
Jo Gent
IEEE Member
Brookline, Mass.
Monroe Postman's suggestion that the relays in the New York City subway tunnels are "fail-safe" simply is not true [Forum, July While they display a low probability of failure, relays are not immune to jamming or to other mechanical problems.
To Postman's question, "... what is the final fail-safe component?," my answer is that there is no fail-safe component and there never will be one. Designs must cater to failure, with the realization that failure is something that cannot be avoided. Can we call this unavoidable failure a law?
Richard Grier
IEEE Member
Lakewood, Colo.
Readers are invited to comment on material published in IEEE Spectrum and on matters of interest to engineering and technology professionals. Letters do not represent the opinions of the IEEE. They may be edited for space and clarity. For additional letters, see "And More Forum..." at http://www.spectrum.ieee.org Contact: Forum, IEEE Spectrum, 3 Park Ave., 17th floor, New York, NY 10016, U.S.A.; fax, +1 212 419 7570; e-mail, n.hantman@ieee.org.