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Letters.

WELCOME BACK, NUCLEAR

To the Editor: I read your article "Reactor Backers" in Mechanical Engineering magazine (August 2001). I am a long-standing member of ASME. "Nuclear energy is gathering political support in the U.S. Congress" -- a wonderful sentence, which expresses a wonderful thought! In fact, it is a wonderful article.

In my view, the main benefit of your article is the summary of the positive political happenings regarding nuclear power in the United States. Mentioning the senators involved by name is a wonderful idea! They are from New Mexico, a state indebted to nuclear power. Bingaman and Crapo are herewith heroes of mine as is Judy Biggert of Illinois.

When I graduated from Texas A&M, I went to work for Westinghouse in Pittsburgh. Initially I worked at the Bettis Lab, then went into commercial nuclear power. I worked my way up to manager of mechanics and materials engineering, supervising the work of seismic analysis of nuclear power plants. I held this job until I left Westinghouse to open my own company, Robert L. Cloud and Associates Inc.

I am looking forward to the recovery of nuclear power in the United States.

Robert Lea Cloud

Staunton, Va.

SOLAR OBJECTIONS

To the Editor: A half aspirin per day, lots of exercise, a low-fat diet, and living in a constant state of total outrage keeps this 83-year-old in great health and spirits. But my memory slips and, at times, I can't remember what it is that I am outraged about.

Then along comes Barbara Wolcott's piece on "Solar Gains," (October 2001) and I am back in business. Try this arithmetic on the back of an envelope: one million solar roofs, each 100 square feet in area; five hours each day of high-noon clear sun; solar flux 100 watts per square foot; 10 percent efficiency; and take 400 days per year to avoid use of a calculator.

What do you get? Two billion kilowatt-hours per year.

The United States is pushing electric energy consumption to about four trillion kWh per year. One million solar roofs will supply one kWh for every two thousand needed. By some journalistic osmosis, pieces like "Solar Gains" find their way into the public press. The impression: We do not need to face another generation of nukes; we can do it with sunshine. What a mistake.

Richard C. Hill

Old Town, Maine

To the Editor: In "Solar Gains," Barbara Wolcott quotes Terry Peterson of EPRI as saying, "It is difficult to compare the cost of power produced by a natural gas facility and that of photo-voltaics." I find this hard to believe.

Although I am now retired, I worked in the field of solar energy and energy conservation for the last 15 years of my active service. One of the first things I learned in this work was that any energy avoidance system, including solar conversion systems intended to be used in a commercial market, such as those for power generation or in domestic applications, needed to be evaluated on the basis of an economic-technical analysis.

Accordingly, I, as well as others, developed such models for this purpose. In fact, it became evident that the only way to determine the optimum configuration of these systems was to use economic factors with technical parameters in the analyses. These models were very comprehensive, including the influence of monetary inflation and cost escalation, capital investment costs, initial system costs, taxes, insurance, value of avoided fuel, etc. The results could be presented in various ways: annual, n-year, and lifecycle dollar saving (loss) expressed in either current (inflated) or discounted (present value) results.

My own feeling is that the preferred form for these analyses was to present the results as life-cycle, present value, return-on-investment (ROI), in percent. In this way, the value of an investment in an energy avoidance system could be evaluated in comparison with a wide variety of other financial investments.

John A. Clark, Life Fellow

Ann Arbor, Mich.

To the Editor: "Solar Gains" does a good job of highlighting the benefits of electric power to off-grid consumers in developing countries. However, the picture of solar's effectiveness on-grid is very misleading.

At today's quoted price of $7,000/ kW installed, and using a typical Californian load factor for solar PV of 18 percent (1,577 kWh energy produced per year per peak kW installed), solar PV power would cost 22 cents/kWh just to pay back capital costs over 20 years. If a 7 percent annual return was required, the price would have to increase to 39 cents/kWh--rather different from the 8 to 20 cents/kWh quoted.

At today's prices, there are many more cost-effective ways to cur power consumption or reduce [CO.sub.2] emissions than solar PV. Efficient appliances and lighting, insulation, and better heating and cooling equipment all save power (or gas, which is efficiently converted to power) at far lower cost than solar PV creates it.

Consider an energy-efficient bulb, costing perhaps $12 retail. If this runs for 18 percent of the time (4 hours, 20 minutes a day), saving 75 W compared to a conventional bulb, it will have the same effect on the environment and your power bill as 75 W of solar PV--which would cost $7x75, or $525.

One final good reason to do all the inexpensive things first: Solar PV seems to be getting significantly cheaper--but huge cost reductions will be required before PV can compete with energy efficiency, particularly in less benevolent climates than California.

Rick Jefferys

Berkhamsted, Hertfordshire, UK.

DATES OF INFAMY

To the Editor: Your editorial on 9/11/01 was well taken, and I trust it will be remembered as we develop ever more sophisticated systems. But, at first I was distracted by your lead-in paragraph. Even though I had some small part in the moon program, I better remember what I was doing when JFK was assassinated and what I was doing on 12/7/41, to say nothing of 9/3/39 as a schoolboy in England, events more akin to 9/11/01.

Allen J Curtis

Palos Verdes Estates, Calif.

THE JUNK LEFT OVER

To the Editor: I recently wrote a letter saying that fuel cells were not the answer to the world's energy problems because of the availability of hydrogen. Well I've been shot down. I saw an article in Popular Science about an auto manufacturer having built a truck powered by a fuel cell that gets its hydrogen from gasoline.

According to the article, the truck uses the gasoline much more efficiently than a "normal" auto does (that is, more miles per gallon). I said to myself as I threw the magazine in disgust at my cat, "Yeah, but what kind of sludge does it leave when it's done extracting the hydrogen from the gasoline, and how do we get rid of that?"

I think my concern is not so much the new technologies we come up with, but that sometimes we forget about the consequences of the new technologies in our quest for "really neat stuff."

Maybe I should not worry about it and feel secure in the knowledge that what I think of others will think of.

Quentin Hilpert

Morenci, Ariz.

GAS VS. GASOLINE

To the Editor: In response to Quentin Hilpert's plea for the Btu value of hydrogen ("Hydrogen From Where?") in the September 2001 issue, the lost is found.

My old thermo book gives the lower heating value at 51,571.4 Btu/lb., and the higher hearing value at 60,957.7 Btu/lb. Assuming that the combustion products are going to be gaseous, let's do the calculation based on the LHV. Dusting off Boyles and Charles Law gives the density of hydrogen as 0.00519 lbs./[ft.sup.3]) at 14.7 psia and 68[degrees]F, and applying that to the lower heating value gives a Bru content of 35.8 Btu/gal. (7.48 gal./[ft.sup.3]).

The same thermo book gives the LHV of gasoline as 18,800 Btu/lb., and at about 7 lbs./gal., that is 131,600 Btu/gal. If the gasoline tank size is 25 gallons to go 400 miles (We're talking SUV, cowboys), it appears that a hydrogen tank size would be 91,900 gallons (they build houses smaller than that).

Of course, this size assumes that the tank is operated at atmospheric pressure, which would require a vacuum pump to get the fuel out. But take heart. If the tank is operated at 3,000 psig, it could be reduced to approximately 450 gallons.

Troy Knffin

Wildwood, Mo.
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Publication:Mechanical Engineering-CIME
Date:Mar 1, 2002
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