Letter - Windmills use power when wind doesn’t blow

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The manufacturer’s spec sheet for the Vestas model V80, a very modern 1.8 megawatt windmill, states that the rotor speed is a constant 15.5 rpm over the full spectrum of wind speeds and power outputs. Furthermore, this same spec sheet says that at wind speeds as low as 7 mph, when the windmill produces no power of its own, the rotor continues to turn at the same constant 15.5 rpm.

Clearly, the power to keep the rotor turning must come off the grid, if the windmill cannot produce power of its own. This would be the definition of “motoring,” which, effectively, the spec sheet says it can, indeed, do.

There really isn’t any reason for manufacturers to lie about this, as Scott Graves claims they are doing. But hey, it isn’t necessary to take the manufacturers’ word for it. Go look for yourself.

At 15.5 rpm, it takes four seconds for the rotor to go around once. Start counting when a blade passes the tower: one-one-thousand, two-one-thousand, three-one-thousand, four-one-thousand; and you will see that same blade is just now passing the tower again.

All modern multi-megawatt windmills use constant rotor speeds, but not all models use the same constant. Some are as low as 11 rpm, which would take five seconds to go once around; some are as high as 20 rpm, which would take three seconds to go once around.

Get in the habit of making this count whenever you see a windmill. Count on those numerous days when the wind is barely blowing; count on those rare occasions when the wind is really howling. See, it’s the same, isn’t it?

And most importantly, count when the wind is so quiet that most of the windmills are stopped. Those few that are turning. Yup, same, again. That would be “motoring.”

Who you gonna believe, Scott Graves or your own eyes?

No doubt maintenance guys don’t want windmills to rotate full-bore when they can’t produce power, but we can’t all have what we want. Issue your complaints to the engineers at Vestas, Siemens and GE.

Just what anti-wind group does Scott Graves think I belong to? Anybody who has been paying attention would know I am not anti-wind.

I think we need electricity, so we should build windmills wherever the wind blows.

And like it or not, the wind here does not blow hard enough, often enough, to generate power. Blame Mother Nature.

Jim Thorn

Dayton