How do wind farms work?

Wind turbines generated 58 percent of Iowa's electricity in 2021 — the highest wind power share for any state, according to the U.S. Energy Information Administration.

As renewable energy has grown in popularity, Alliant Energy has secured its spot as the third largest utility owner-operator of regulated wind in the United States. The company now owns eight wind farms in Iowa after adding 1,000 megawatts of additional wind generation in the state between 2018 and 2020.

English Farms Wind Farm, located in Poweshiek County, is one of those farms. It spans 19,000 acres and boasts a 170-megawatt maximum capacity, if operating at ideal conditions. Sixty-nine wind turbines dot the landscape, each standing around 500 feet tall.

The Gazette toured the English Farms Wind Farm with Alliant Energy staffers to learn more about wind energy and wind farms. We spoke with senior operations manager Tony Vaughn, wind technician Luke Peters and Alliant spokesperson Morgan Hawk. Their answers are edited for brevity and clarity.

Q: How do wind turbines operate?

Vaughn: When we hit start for a stopped turbine, it's not going to come right back online. It’s going to look at all the different wind speeds, temperatures and any movement to make sure they’re in the right range for the turbine. If you think about your vehicle, it has set points the temperature must be within in order for it to run. It's the same thing on the wind turbine. If all of them are within the ranges, then the turbine says, “OK, I'm ready to run.”

There are different parameters that will shut the turbine down if it's too hot or too cold. If it gets under a certain temperature, some parts will start getting brittle, so you don't want to operate the turbine under extreme cold. Very rarely does it get to that temperature. The turbines that we have here use special oils and foam insulation to protect them during the winter.

Q: How do turbines generate energy from the wind?

Vaughn: As a turbine sits, it has a controller telling us which way the wind is coming from and the speed of the wind. That will tell the blades what angle to pitch at and how many revolutions per minute the turbine should be turning.

Those blades catch the wind, just like an airplane wing. It creates a turning motion. The motion turns a gearbox that spins a generator to produce the power. As there's more wind speed, the controller can tell the generator to produce more power. More wind speed means there's more rotational force on the generator, so it can produce more output.

Q: How does the energy get to the power grid?

Peters: When the blades spin fast enough, the turbine will start putting power out. That energy comes down into a converter that cleans up the power. It takes any weird spikes and voltages — anything the grid’s not going to like — and sends the energy out to the transformer.

Vaughn: Then, the energy goes underground to a substation, where it will be bumped up to the transmission line voltage and put on the transmission lines. The neat part that a lot of people don't understand is that the power is staying here. For every substation that ties into this transmission line, it's first come, first served.

Q: What needs to be considered when turbines are built?

Vaughn: As they're planning out these wind farms, they're monitoring the wind and seeing if it's a good wind regime to put wind turbines in. Once they determine that, then we go out and talk to landowners and make sure they’re on board. Once they're signed up, we're looking for the higher spots that get the better wind regime. If we were to put turbines on lower ground, you're missing out on wind and could have flooding issues.

There’s also different setbacks that we have to follow. There's some counties that have setbacks and some that don't have setbacks. We need to stay far away from eagle nests, wildlife refuges, wetlands, wet areas — things like that. Most developers use an industry standard for their setbacks to prevent issues for landowners in the area.

We also look at birds and bats. Any time we find any birds or bats around the turbine, we report it to the U.S. Fish and Wildlife Service. We're actually working with them at all of our wind farms to create a habitat conservation plan for bats and birds. We’re trying to do different programs to shut turbines down or reduce their output when there's bats in the area.

Q: How do the land agreements work with turbines on croplands?

Vaughn: In the case of English Farms Wind Farm, the developer made lease agreements with each landowner. We pay an annual payment to the landowner for the turbine location and for roads, cables and things we have to put underground. That payment will vary throughout the United States in different areas of the country per the going rates.

Q: Do you get any pushback from people about wind farms?

Hawk: The simple answer to your question is that our landowners are voluntary. We work with landowners who see the benefits of wind, the environmental impacts, the lease payments they receive. Those relationships with landowners are a huge key at the beginning.

Vaughn: We have never condemned any property, and we won't. We want to be a good neighbor when putting in these wind turbines. I would say the people that maybe aren't as thrilled with wind turbines are the tenants that have to farm around them. They’re not getting anything from the wind power because it's not their property.

Q: What's the life span of a turbine?

Vaughn: Life span of turbines, in general, is approximately 20 years. That can even go farther, depending on what type of maintenance you've done. But we have coal plants that had 20-year or 30-year life expectancy. And they’re how old now? So, with the right care, you can continue their life spans for quite a while. Older turbines are probably performing just as they have over the last 13 years. They're still performing great.

Brittney J. Miller is an environmental reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com