Alliant Energy has received approval from the Iowa Utilities Board to add an additional 500 megawatts of windpower to 500 that was previously approved.

Alliant spokesman Justin Foss says they plan to have the additional capacity built by 2020 and it will provide enough energy to power 430,000 homes. The company plans to add the wind turbines at several locations. Foss says they plan to begin construction to expand the Whispering Willow Wind Farm in Franklin County next year. They will also add turbines to a western Iowa farm.

“As soon as this snow starts to die down we are starting construction on another wind farm up in far northwest Iowa in Clay and Dickinson counties on our Upland Prairie Wind Farm — that’s a 300 megawatt unit up there,” Foss says. “The goal is to start getting some foundations in this spring and summer and to start erecting some turbines later this summer and to have that online through early next year.”

Foss says they are benefiting from the improvement in turbines and says they saw that from the approval of the first 500 megawatt project to the second. “In the second project our cost per unit is actually lower and that reflects the fact that the technology continues to improve and costs continue to go down,” Foss says. He says one thing that is improving is the size of the power generator for the turbines.

Recent generators were 1.65 megawatts. “The new ones we are going to be installing are 2.5, so they are quite a bit bigger,” Foss says. “Not only that, but the blades are a lot larger as well. And a larger blade allows you to capture more wind energy. And therefore means that you are able to generate a lot more energy at a lot lower wind speeds.”

Foss says the expansion, combined with existing wind farms and market purchases, will allow the company to get approximately one-third of its Iowa total capacity from wind energy by the end of 2020.