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Wednesday, 02 September 2009 13:59

The Naturalist's Corner

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What’s good for the goose

In his latest letter to the editor in Smoky Mountain News (8/19/09) the Canary Coalition’s executive director, Avram Friedman admonishes us to “stick to factual information” and calls Tonya Bottomley’s range of 40 to 70 acres per turbine, “grossly inaccurate”

Ms. Bottomley’s range is correct even according to American Wind Energy Association’s own figures. “Wind projects occupy anywhere from 28 to 83 acres per megawatt, depending on local terrain, but only 2 to 5 percent of the project area is needed for turbine foundations, roads or other infrastructure.” – AWEA.

But Avram is right – this is grossly inaccurate. AWEA knows this is inaccurate and one would assume that the director of the Canary Coalition knows this. The reason this is grossly inaccurate is because the “megawatt” AWEA is referring to above is the “rated capacity” – that Oz-like figure that emanates from behind the curtain – that means in the perfect windy world, where the wind blows constantly at around 25 m.p.h. or so a 1.5 megawatt turbine would actually produce 1.5 megawatts of electricity. Pull the curtain and there stands the Wiz with his hand on the 28 percent throttle.

The Energy Information Administration notes that the average “capacity factor” (actual amount of electricity turbines supply to the grid per year) for wind is around 28 percent. Which means that wind projects occupy anywhere from 28 to 83 acres per .28 megawatt.

Now there is a caveat. AWEA also states that, “A wind plant located on a ridgeline in hilly terrain will require much less space, as little as two acres per megawatt.” Of course they mean per .28 megawatt and they must be talking about just the footprint of the turbine because I can’t find any actual installation where only 2 acres of land were disturbed per turbine and they’re not including any property-line offsets.

The trade off comes because turbines on ridgelines are strung out singly in a linear progression a la Buffalo Mountain. So instead of a plot or 500-acre parcel of land for 18 turbines you get a 2-mile strip. Avram seems to imply that Buffalo Mountain is a typical site location one would encounter along the ridges of Western North Carolina. I don’t think so, as Buffalo Mountain was already basically cleared – the site of an old strip mine.

And Avram states as fact: “This 29 megawatt project provides enough energy to power 3780 homes according to TVA.” At least he attributes the statement to TVA. But he knows better. TVA knows better too and even admits, “The new turbines are expected to have a capacity factor of 28 percent because the towers are 49 feet taller. The low capacity factor is related to the availability of the wind resource in the Southeast.” (http://www.tva.gov/greenpowerswitch/newsletter/vol5_1/gpsnews_vol5-1.pdf.)

Remember 29 megawatts is the rated capacity. TVA admits they will only produce 28 percent of this rated capacity. So if you wanted to put it on a per home basis (which you really can’t do) you would be looking at 1,058.4 homes. Not the 3,780 stated as factual information.

And to put this in perspective let’s look at an actual forested ridgeline wind farm. Mountaineer wind farm in West Virginia consists of 44 turbines stretched along a 50-foot wide newly constructed service road that runs for 4 to 5 miles. Approximately 5 acres of forest were cleared per turbine.

In one of Avram’s previous, letters to the editor, he noted that the ridgelines of Western North Carolina could produce 1,000 megawatts (rated capacity) of power. Any idea how much area TVA estimates would be required to produce 1,000 megawatts (rated capacity) or 280 megawatts (capacity factor) of actual electricity?

“For instance, one 1000 megawatt nuclear unit requires 1,000 acres. It would take 12,160 acres of wind turbines, or 23,760 acres of solar panels to generate the equivalent amount of energy as the single 1000 megawatt nuclear unit.”

I salute Avram’s desire to stick to factual information regarding wind power. A good place to start would be replacing rated capacity with capacity factor and let’s talk about the actual electricity produced.

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