To the Editor: The Intergovernmental Panel's new report on climate change shows that burning more and more fossil fuel is causing potentially devastating changes. The obvious answer is switching machines. Solar energy can be effectively converted into power. But it is dependent on sunshine. Many installations would be needed to replace even one of today's central power stations running on coal or natural gas. Windmills and other renewables often require a lot of land.

So what other non-fossil choice do we have? The nuclear reactor. But the Chernobyl disaster—and, to a much lesser extent, Three Mile Island—have cast a dark shadow over this choice.

Comparing safety records of the world's four types of large-scale power sources, Switzerland's Paul Scherrer Institute reported deaths from coal power were actually 42 times greater than from nuclear over the period of 1970 to 1992. Indeed, nuclear power had a much better record than even natural gas or hydroelectricity, possibly in part because so much attention is paid to safety.

My guess is that part of coal's dismal record has to do with mine disasters and black-lung disease, although acid rain and mercury belched into the atmosphere are also quite damaging to people's health and the environment. (The listing may or may not include the various causes of death associated with the other energy sources; for example, deaths from mining uranium ore, from hydro-dam failures, and the fires and explosions involving natural gas.)

Since we cannot do much more with hydro, the only other known, reliable, 24/7 major non-fossil power source possibility is nuclear. At the same time, of course, we should do what we can with windmills and other limited-power generators, while drastically reducing our electric power demands. But time is of the essence: Global warming is now accelerating.

Milor- ganite Revisited
William Billett
Fairmont, Minn.

To the Editor: I apologize for the error made in dating the availability of Milorganite (Letters, Sept. 2006). My mother bought a bag of Milorganite during the Second World War from Mr. Stevenson, a hardware store owner at 50th Street and Penn Avenue South in Minneapolis, who told her of its origin. She repeated the information to me.

My brother and I were amazed at the lack of any particular odor from the material, compared to some sheep manure my grandfather had brought from Colorado for the same purpose of fertilizing our lawn.

Editor's note: According to the Milorganite.com Web site, the Milwaukee Sewerage Authority began marketing Milorganite in 1925 to make use of solid byproducts of the city's wastewater treatment plant.

To the Editor: I enjoyed Annette von Jouanne's article on extracting energy from the waves ("Harvesting the Waves," Dec. 2006). Her comment that "interest in extracting power from waves began in earnest in the 1970s" is certainly true. Your readers may be interested to know that two ASME members were involved in this effort: Michael McCormick and the present writer. At the time, we were both members of the faculty at the United States Naval Academy, and in 1974, 1975, and 1976 we each conducted projects for the U.S. Coast Guard.

The Coast Guard was interested in evaluating a device called the Wave Activated Turbine Generator, or WATG. This device was invented in Japan, by Y. Masuda, in the late '60s. It consisted of an air column with an air turbine and generator installed on top of a buoy with a central pipe open to the sea at its lower end and to the air at its upper end. The relative motion of the buoy and the water column forced air through the turbine and thus turned the generator.

The idea of tethered buoys generating electricity from ocean waves seems to go back at least 30 years.

The Coast Guard deployed and serviced many thousands of buoys, most of which had battery-powered navigation aids. If wave energy could be used to keep the batteries charged, significant savings would accrue.

McCormick's project was to conduct an analysis of the buoy-WATG system. He reported his results in the Journal of Hydronautics and presented a paper on this subject at the ASME Winter Annual Meeting in 1974. My project was started in the summer of 1975 and was to extend McCormick's work to include the internal valve system, the turbine, the generator, and the electric load. In addition, I was to include various nonlinear elements and feedback paths previously assumed to be negligible. My report was published by the Coast Guard in January 1976.

My second task was to conduct tests to determine the turbine-generator parameters defined by my model. A report was sent to the Coast Guard in 1977.

The conclusions of all of these efforts were that data from field tests was urgently needed to establish the true energy dissipation mechanisms. I never found out if such tests were conducted.

To the Editor: Please relate my thanks to Prof. Annette von Jouanne for the use of SI units only in her well-written article, "Harvesting the Waves" (Dec. 2006, pages 24–27).

To the Editor: After reading the article by Annette von Jouanne and then looking through my library, I found Kent's Mechanical Engineers Pocket-Book, published by John Wiley & Sons in 1903. Pages 599 and 600 have some interesting information. The article refers to a Mr. Albert W. Stahl, U.S.N. (Trans., A.S.M.E., Xiii. 438). ASME? That sounds familiar.

Apparently, people knew there was energy in the waves even back in 1903. Why then do we have all these nasty polluting fossil fuel power plants? Could it possibly be there isn't any money to be made by producing electricity from the waves? Or the wind?

The question isn't if wave, wind, or solar energy is possible. It's when we will be willing to pay for it. We need a reason to build power plants that lose money. You would have to force people to pay the higher production costs. How do you do that in a democratic free trade society? Through political change; get them to vote for it.

E=1/2 M V². It's the V² that does it. High-pressure steam coming out of a turbine nozzle has a lot more velocity than the wind. Water falling from the Hoover Dam has a lot more velocity than water falling from the crest of an ocean wave.

To the Editor: In the article "Harvesting the Waves" by Annette von Jouanne in the December 2006 issue of Mechanical Engineering, I draw your attention to the mistake in using the unit of MW when referring to the "energy consumption" on page 25.

This journal being intended for the engineering public (as opposed to "popular" science) should assure better quality in reviewing its articles.

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