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22 August 2003
E-Bulletin Backscatter
Sheldon:
The article on wind power by Forrest Mims is a bit too optimistic and deserves some qualification. First he does demolish the fallacious argument about the destruction of birds by windmills. Even the estimates of the number of birds killed by other human activities and structures is suspiciously high. To kill 40 million annually at cell, radio, and TV antennas would result in piles of bodies beneath each; and if 1 billion were killed in collisions with glass windows, then why would cities be employing Falcons to rid themselves of pesky pigeons, blackbirds and sparrows?
Here in the Northwest people are "green" and very interested in wind power. Those in the Portland area have the opportunity to pay an extra surcharge to support its development. They gladly accept the offer to pay extra. I'm all in favor of developing sustainable energy, but before we swoon over wind power, let me point out a couple of enthusiasm-tempering facts.
Mims refers to 1,500kW generators on the Texas windmills. But, the bulk of current installations use generators more in the neighborhood of 500kW. These do not supply this amount of power on a continual basis, but rather only when the wind speed and direction is optimal. Both too much and too little wind is detrimental. The actual wind-to-wire efficiency might be 30-50% on an annual average. A large coal-fired station, like Jim Bridger in southwestern Wyoming has 3 generating units with a total capability of 4,500,000kW. These generate as long as coal goes into the boilers -- being down for perhaps two-weeks each year for maintenance. Therefore, it takes something like 7,000 to 15,000 wind turbines to replace 1 Jim Bridger; and you can plainly see that wind power is more demanding of some environmental resources, such as surface space, than is coal-fired power. It is one thing to smile upon two wind-farms along the road from San Antonio to Los Angeles, it is quite another to view 15 wind turbines per mile along the whole trip. By the time we build enormous wind-farms near cities we have no idea what will be the effect on urban climate, air quality and quality of view. Presently people are making fun of Walter Cronkite for opposing a small wind-farm that will impact his ocean view, but he undoubtedly sees this as the vanguard of a truly intrusive system, and I almost sympathize with him.
Moreover the size of the synchronous machines at Jim Bridger have so much rotational inertia that they produce very accurate 60Hz power independently of variations in demand. The wind power I'm familiar with, and I'm sure it is improving all the time, is not so accurate, and requires a lot of additional equipment and technology to make it comparable.
Finally, despite the final allusion in Mims article, wind power cannot replace the West Texas pump jack. Something like 40% of the demand for petroleum is to run automobiles, trains, and trucks. There are practically zero automobiles that can run on wind power at the present time, and it will be difficult to ever get battery powered cars to compete with gasoline powered ones simply because of the huge disparity in energy density between gasoline and batteries.
Kevin Kilty
Forrest Mims responds:
Kevin Kilty suggests that my column on wind power exaggerates bird kills and benefits derived from wind power. While I appreciate his comments, the facts support my column.
The numbers of birds killed by communication towers has been the subject of various studies, some lasting more than 20 years. I consulted some of these studies before writing my column and am surprised that Kilty seems unaware of them. A good summary of the literature is Avian Mortality at Communication Towers: A Review of Recent Literature, Research, and Methodology , March 2000, Prepared for United States Fish and Wildlife Service, Office of Migratory Bird Management, Paul Kerlinger, Ph.D. See http://migratorybirds.fws.gov/issues/towers/review.pdf
Estimates of the number of communications towers I have seen range from 50,000 to 77,000. The disparity in the numbers is likely due to the very rapid increase in the number of cell antennas and the fact some studies report the number of towers higher than a specific height or only some categories of towers (e.g. those with and without guy wires).
Let's assume there are 60,000 towers. If 40 million birds are killed annually by these towers, then each tower kills 1.8 birds per day. Most kills occurs during the spring and fall migrations. Since there are well documented instances (see above review) of individual towers killing hundreds or even thousands of birds during the migratory season, the 40 million total is not unreasonable.
Kilty writes in praise of coal-fired power plants. I would share his enthusiasm were it not for the fact the plants he praises have caused major ozone problems for the San Antonio region and many other cities. When the plumes of the two coal-power plants southeast of San Antonio blow across the EPA's ozone monitors, ambient ozone increases by from 8 to 21 parts per billion. This has placed San Antonio in violation of the EPA ozone regulation, and now all the surrounding counties, including mine, are faced with possible mandatory emissions testing and many other unworkable control strategies that will have absolutely no impact on those coal plant plumes.
Moreover, those two coal plants emit more than 640 pounds of mercury each year. Coal is a major source of airborne mercury, which has tainted reservoirs and lakes all across the U.S.
The coal problem is why my county appointed me to represent them on a regional air quality committee. The county with the power plants wants to keep the status quo. The surrounding counties don't want to be sanctioned because of their neighbor's dirty air. The government regulators love these kinds of disputes, because they will win in the end.
As for my closing comment about the derelict oil well pump, it's as useless today as when I took the photograph. The wind generators nearby are still spinning. Of course wind power will not solve all our electrical needs. But if it can provide a few percent, as in San Antonio, why complain?
Forrest M. Mims III
Vice-Chairman, Environmental
Science Section
Texas Academy of Science
Guadalupe County representative:
Alamo Area Council of Governments (AACOG) AIR Advisory Committee
AACOG AIR Technical Advisory Committee
Air Quality Advisor
Guadalupe County Commissioners Court
Geronimo Creek Observatory
Measurements of and scientific papers about total ozone, total water vapor, solar ultraviolet, aerosol optical thickness and many other Sun and sky parameters since 1988.
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A Question on Spontaneously Disintegrating Glass
My sister was sitting in her room watching television and a glass cup with a handle spontaneously distintegrated throwing glass pieces up to two feet away. There was nothing in the glass at the time, though she had recently been drinking a cold beer from it. The cup was about 4 inches high and 3 inches in diameter. There must be over 100 pieces, the largest about an inch long. Does anyone have any information about what could have caused this? Was Maxwell's demon at play?
Johan Benson
