Large, white wind turbines dot the land in Dodge and Fond du Lac Counties.
TODAY’S TMJ4 got a look inside to see how the science of wind energy has evolved.
In the past decade, 466 wind turbines have popped up across Wisconsin on 18 different wind farms. The largest one, We Energies' Blue Sky Green Field, is in Fond du Lac County.
"So these 88 turbines are spread across 11,000 acres. The actual footprint of the tower and access road is about 44 acres,” said Steve Schueller, the supervisor of Blue Sky Green Field.
Schueller says it's the perfect location. It is on a ridge, and Lake Winnebago to the west provides a "clean" wind. That means there are no buildings, trees, or hills to obstruct the wind.
Contrary to what you might suspect, a higher wind speed does not rotate the blades faster. They always rotate at a constant speed: 14.5 RPM.
It won't go faster, but it will make more power. The blades actually pitch 90 degrees to catch more or less wind. It's a matter of force.
Speaking of force and stress. The life expectancy of a wind turbine is 30 years.
“The stress that the tower sees is quite immense, and in gusty winds you can actually see sway,” Schueller said.
That’s right they sway, a few feet in each direction. Wind technicians working on the tower say it’s like being on a ship.
To keep the tower upright, the base is attached to bolts that are 9 feet long and buried in a 50' wide by 10' deep hole filled with 325 yards of concrete
"I am guessing this is like a car and needs routine maintenance. The towers are maintained every 6 months..." Schueller said.
He pointed out that they build where it is windy, but you have to have low winds to do any maintenance.
"The center of the rotating hub is 262 feet above the ground,” Schueller said.
Each blade is 134 feet long, and when it is straight up, the wind turbine is 397 feet high.
But how do you get up there?
"We are in the base of the tower, and over here you can see the ladder that is used. There is no lift, so the only way to the top is by climbing a ladder. This ladder goes 262 feet up. That's 26 floors...straight up,” Schueller said.
And wind turbines are heavy.
"The entire wind turbine weighs 250 tons. The rotating part, the hub and 3 blades weigh 50 tons,” Schueller said.
For reference, an 18 wheeler weighs 40 tons. So how much wind is needed to turn these massive blades?
"You would think a lot, but these will rotate with as little as a 4 or 5 mph wind speed,” he said.
The towers can withstand 200 mph winds, but automatically shut down when the wind gets too strong.
"They will shut down in high winds over 45 mph for a 10 minute period. Any 50 mph average for a minute, or 60 mph wind for a second, they shut down,” said Schueller.
On the top of the turbine, there are two wind sensors, or anemometers. Those sensors provide wind speed and direction.
That information automatically tells the blades which direction to face.
Now the all important question: How is the wind turned into electricity? The blades collect the wind.
That force gets sent to the gearbox and generator which converts that mechanical energy into electricity.
All 88 turbines are connected by wires underground. They feed into a substation. From there power lines transfer the energy into the grid and the grid powers America to the tune of 345,000 megawatts of power each year.
That’s enough energy to serve 45,000 households. Energy that's safe, reliable, efficient, and clean.
Wind power only accounts for 3 percent of We Energies’ electricity production, but it is a huge boost to help reduce their carbon emissions by 40 percent below 2005 levels by 2030.
So does We Energies have any plans on building more wind farms?
Wisconsin ranks 23rd in the country with the number of turbines, but at more than $3 million per tower, We Energies is now focusing on developing solar power that has become more economical.
And make sure you call them turbines, not windmills. That will anger a wind technician very quickly.