To the Editor: I just wanted to let you know that I enjoyed your editorial, "Remembering the Shuttle Columbia" (March) very much. It seems that everything you hear or read of late concerning Columbia deals with the technical side of the accident and what went wrong.
Your editorial was awesome and heartfelt. Tragedies like Columbia and Challenger shake the world, but mainly the engineering community, to the core. Things like this remind us that, even though we engineers strive for perfection, we are only human. Thanks again for the great editorial.
Scott Cline, P.E.
To the Editor: Just a short note to say that the articles in the April issue were really interesting and very readable. Good job.
I particularly enjoyed the article on "Powering Down," which I knew nothing about. Being a Columbia alumnus, I would have thought I would see this in the Engineering Times from the school.
"The Planetary Crankshaft" is something new and revolutionary, and nice to see.
"Giving Vent" was third, although I don't see it as a major player the way it is designed, but that may change as the concept improves. Anyway, well done.
Old Bethpage, N.Y.
To the Editor: Our nation's real need for a viable long-term solution to renewable energy, especially for private transportation, is not well served by articles such as that by Michael von Spakovsky in the June issue, which paint a fanciful picture of the promise of fuel cells.
The total cost (without subsidy) of proton exchange membrane fuel cell engines (fuel cells, power conditioning, electric motors, etc.) with mass low enough to be practical in a vehicle is in the range of $4,000 to $8,000 per kilowatt—40 times that of the advanced diesel engine.
It is worth noting that PEM fuel cells have been in use and development for 40 years, and costs have not yet begun to drop significantly.
The huge mass penalty associated with economical hydrogen storage seems likely to keep the mileage of fuel cell-powered automobiles (of acceptable range, acceleration, cost, and cargo capacity) quite low for many decades.
It is most interesting to note that seven years ago, the Department of Energy expected fleets of fuel cell-powered vehicles to be in use by now. Today, they are projecting that will occur seven years from now.
I expect to still see that "seven year" projection 20 years from now.
It's time we start putting some serious money into real options for our future transportation needs.
F. David Doty
To the Editor: I read "Stacking Up" in the June issue.
Everyone speaks about low emissions and shows numbers for fuel cells. They also say that some systems use petroleum as a fuel. Michael von Spakovsky speaks of a methanol-based system.
Methanol is only made up of carbon, oxygen, and hydrogen (CH3OH). So what happens to the carbon? In the other systems, what happens to the stuff that isn't oxides of nitrogen, carbon monoxide, and volatile organics?
Are we going to have to get rid of this stuff eventually, or is it nothing to worry about? I'd like to know. No one has really said, and I am a strong believer in the saying, "There's no such thing as a free lunch."
Another question on fuel cells: It would be interesting to find the efficiency of a reciprocating gasoline engine from the pump that takes it out of the ground, refining, etc., to draw bar and compare it to the efficiency of the fuel cell from hydrogen generation plant to draw bar.
Petroleum isn't just black stuff pumped out of the ground. It's canned, concentrated sunlight. We will run out of it and, yes, we need to find an alternative. But let's make sure the alternative is better before we jump on the bandwagon.
Me? I hope the guys in "Tracking Fusion" get lucky because that's the only way I can see of making hydrogen without needing some sort of fossil fuel in the process.
York Valley, Ariz.
Burn Your Veggies
To the Editor: In the Letters section of the February issue, Lawrence Kamm stated, "There is no known way to generate any adequate gasoline, or even diesel, equivalent other than by refining petroleum ..." which I believe is not true.
For example, biodiesel is produced by refining vegetable oil, runs cleaner than petroleum diesel, and is already available to consumers at some marinas and card lock fueling stations.
Here in Berkeley, Calif., the city's recycling trucks run on it. (If the simple chemical reaction required to produce biodiesel doesn't appeal, Rudolph Diesel's original engines ran on un- adulterated peanut oil. With a fuel system modified to preheat vegetable oil and lower its viscosity, so can most current diesel engines.)
Biodiesel is much closer to being viable on a large scale than hydrogen, is carbon neutral, can be made in the United States, and is simple enough to make so you can do it yourself in your garage (see www.veggievan.org for information). It sometimes seems that energy policy (and the money that goes with it) is aimed at nurturing long-shot "high-tech" dreams while maintaining the status quo, rather than achieving practical energy solutions.
William David Lubitz
To the Editor: In the article "Carbon Underground" by Jeffrey Winters in February, Prof. Klaus Lackner of Columbia University reported a figure for wind energy being 600 watts passing through a square meter. I assume that is for a ground-based wind turbine site.
At high altitude, the wind energy passing through a square meter is higher by more than an order of magnitude at most locations in the United States. The energy in the summer months is much less, but still not bad.
The question is not, "Is the energy there?" but, "Can it be captured practically and economically?"
We are convinced that it can be, and intend to prove it. The technology is described on our Web site, skywindpower.com. Our figures show that, long range, we should be able to generate all the electrical power the U.S. will need at about one cent per kWh, and produce hydrogen by electrolysis of water in quantity to supply our other energy needs from additional electricity generation.
In our view, this whole subject of meeting U.S. energy needs and global warming is incomplete without considering this technology. We'd be glad to go into much greater detail about this technology and the implementation we are undertaking if it is of interest.
David H. Shepard
Sky WindPower Corp.
San Diego, Calif.
Clearing the Air
To the Editor: I was intrigued by the article "Giving Vent" (April). I personally have suggested such systems for HVAC projects I have worked on in the past, only to have those ideas turned down by my employer, or the owner, on the basis that it was too radical or it did not satisfy the design criteria. A couple of comments, however.
A paragraph begins, "One of the more common ways to do this involves mixing recycled air from the exhaust stream with fresh air drawn from outdoors." "Exhaust air" is an incorrect term; it should be "return air." Exhaust air is typically air that is removed from the building toilets, janitor closets, and other spaces required by building codes to be ventilated directly to the outdoors. No HVAC system ever recycles exhaust air.
The second issue I have is with the idea of utilizing the building plumbing sprinkler system as the cooling medium for the radiant cooling panels. The typical fire sprinkler system is closed—that is, no flow. According to physics, "goes into must equal goes out of."
Unless the water in the plumbing sprinkler system is mechanically cooled, the heat removed from the building for cooling will gradually heat up the water in the piping until the temperature of the water approaches the space temperature. Cooling capability will therefore also gradually diminish.
I was pleased to see that the radiant cooling panel condensation concern was acknowledged and discussed, from a "been there, done that" perspective.
Siddhartha Kamath, P.E.