Kansas Snapshots by Gloria Freeland - February 12, 2021
From pinwheel to powerhouse
Every youngster from my generation at some time played with a pinwheel on a stick. It was somehow fascinating watching the
plastic blades whirl as I blew on them. Holding it out of a window of the family car meant the fun was continuous.
Its "big brother" was a familiar companion used to pump water on our farm. Electricity hadn't reached it when my parents were married, making the windmill an important labor-saving device. Still, I always thought of the many windmills dotting the Kansas prairie as more a remnant of the past than a precursor of the future.
But that began to change about 2000 during a visit to the former East Germany. Giant windmills were sprinkled here and there, producing a sort of surreal landscape. On one quiet country road, husband Art stopped the car and we walked the access drive until we were under the huge blades. We heard a vague humming sound and also a gentle "swoosh" when an individual blade was nearest the ground, and so nearest us.
Today, we certainly don't have to do much traveling to see these big windmills, particularly in places noted for winds, such as where the sea meets the land or the windy Great Plains. While they have found homes in Kansas fields and pastures, they can also be seen on interstate highways in their disassembled state. Heading to Wisconsin last week, we saw frequent “Wide Load” mini-convoys of three vehicles. A car sporting a yellow flashing light came first, then a truck with one of the windmill's components and finally a trailing car that looked much like the first. Sometimes the lead vehicle had a tall flexible pole set to the height of the tallest point of the truck's load and probing the area ahead to make sure there was adequate clearance for the part in transit.
In the quest for energy to power our world modern, the only answer for years was to burn coal or hydrocarbons, such as oil and natural gas. What was available from environmentally-friendly hydroelectric plants was woefully inadequate. Nuclear power was once thought to be a non-polluting answer, but decades have passed since the first nuclear plant went online, and we have yet to solve the problem of the radioactive waste they generate.
But solar power and wind power are now mounting a potent challenge to carbon-based energy generation. Those windmill parts we saw heading down I-80 won't be pumping water to pastured cattle; they will be generating electricity!
Being an electrical engineer, it didn’t take much prompting for Art to share some facts as he has spent time in the past satisfying his own curiosity:
- Two-bladed rotors wobble when spinning, but more blades increase the wind force against the tower. Three blades is the best
- Most windmills have systems to turn the rotor so it faces into the wind.
- Rotating the blades changes the amount of surface the wind can push on and so adjusts the power output. If the blades are turned so they are parallel to the wind, the rotor stops.
- Winds are steadier and stronger farther from the ground, so most towers are 300 feet tall. Blades are typically 60- to 200-feet long. Useful wind speeds are in the 10- to 50-mph range.
- While they get bigger every year, a typical land-based unit today will generate 1,500,000 Watts (1.5 Megawatts) with a 30-mph wind. In most windmills, the slowly-turning rotor is connected to a gear box whose output is at an increased speed. The generator can be smaller if it is turned more rapidly.
- If winds were steady and optimal, it would take about 3,000 of today's typical windmills to provide all of Kansas' electrical power - about one for every five-mile-by-five-mile piece of the state's land.
- Units are designed for a 25-year life and cost about $1 for every design Watt. So, a l.5 Megawatt unit costs a cool $1,500,000.
- The blades are made of a composite materials such as glass and carbon fibers. Each windmill has built-in status sensors to monitor its health, but a human inspector/maintenance person visits three times per year. Those technicians have to be in good shape because getting to the top is usually by steps!
- The biggest problem with the windmills is that the wind is not always blowing and so, does not always provide power when needed. But even with this limitation, the windmills now contribute about eight percent of the total electrical energy we use.
Denmark was an early adopter of sea-based units and is home to Vestas, the biggest manufacturer of the turbine portion - the
part at the top of the tower that contains the generator. The first real “sea farm” with floating windmills is an installation
of five 6-Megawatt units 20 miles northeast of Scotland in 350 feet of water. The units float and are held in place by cables
attached to the sea floor. Electricity is brought ashore by an underwater cable.
While windmills are not bird-friendly, the bird fatalities at windmill farms are less than 10 percent of what they are at a conventional power plant of the same capacity, where deaths are caused by high temperatures, being drawn into air intakes, pollutants, etc. According to Wikipedia, these wind farms account for less than a millionth of those killed by cats, buildings or automobile grills.
I must admit I enjoy watching the slow sweep of the blades, but am unsure how I feel about seeing them stretch across the once open prairies. Still, the white house with the nearby red barn and small windmill that meant home to me as a child may have been an affront to the Native Americans and Voyageurs who lived in Kansas before the Freelands arrived.
Daughter Mariya's name was inspired by a song from the 1950s musical, "Paint Your Wagon." One lyric from it is, "... Mariah blows the stars around and sets the clouds a-flyin'." But things have changed since then. In 2021, we could add that it also helps light our homes, cook our suppers and power our computers.
Upper-left: my grandparents Mostrom farm in Morris County, Kansas. The ubiquitous windmill is in the very center. Upper-right: windmills on the Kansas prairie in Ellsworth County. Lower-right: three of a series of windmills in shallow water as our plane approached Copenhagen, Denmark in 2013. Lower-left: map showing average wind velocity over the continental United States at a height of 250 feet. The black dot locates Manhattan, Kansas. Immediately to the right is the velocity color coding chart. Lower-middle: a chart ranking the states by the percentage of energy generated by wind power in 2017. The map and chart are from the National Renewable Energy Laboratory.