Thanks to Chris Gibbar for reading my letter, and for getting windmills’ embarrassing failures into print a second time.
But the retelling has a hugely important error: “Turning” does not necessarily mean “generating power.” If you are the pilot in your thrice-weekly jaunts back and forth to Portland, you would already know this; if not, get a pilot to explain how a constant-speed propeller works.
Basically, big commercial windmills always turn at one of only two speeds: Stopped or full-bore. When the wind blows really hard, the windmills turn full-bore, with their blades set to accept the greatest wind force, putting lots of power onto the grid.
When the wind blows sorta hard, the windmills turn full-bore, with their blades set to accept a little wind force, putting a little bit of power onto the grid.
When the wind blows gently, the windmills turn full-bore, with their blades set to accept no wind force, putting no power whatsoever onto the grid. When the wind barely blows, the windmills cannot turn at all without help, and so would drift to a stop, except for the fact that windmills cannot remain stopped for very long or their blades will warp, and their shafts will droop, and their bearings will develop flat spots and their hydraulic oil will turn to glop. (Not a very scientific term, I know, but anybody who has left their lawn mower outdoors over the winter will understand.)
During those long windless periods when electricity demand is high, it is necessary to remove power from the grid by using the generators as electric motors, to keep the windmills turning full-bore, with their blades set to exert no force on the wind.
There you have it. If windmills are turning full-bore, they may be putting power onto the grid, or they may be drawing power off the grid. The only way to know which is to measure the wind speed.
Of all the ways of getting out of town, flying expells by far the most air pollution.
I think Chris Gibbar should look at Doppler weather radar maps, where he can confirm from the pollution-free comfort of his living room chair, that yes, indeed, the Columbia Gorge windmills are turning virtually all of the time, consuming the power faithfully generated by the local area’s coal- and gas-fired plants during periods of extreme heat and cold.
Remember: “Turning” is not “generating.”