The company would become the first investor-owned US utility to offset 100% of its customers’ electricity usage with renewable energy once its proposed Wind XII project is approved and commissioned, the company claimed.
MidAmerican formally filed the proposed project with the Iowa Utilities Board on 30 May.
The utility expects to complete the site without increasing customers’ rates by late 2020, it stated.
A turbine supplier and the precise location of the wind farm have not yet been specified, but the company stated it is currently exploring potential locations.
MidAmerican company’s president and CEO Adam Wright said: "Wind XII will transform our 100% renewable energy vision from a bold dream into reality."
The utility has set a target of offsetting total energy usage of its customers in Iowa, Illinois, Nebraska, and South Dakota with renewable energy by 2021. It will continue to use its natural gas, nuclear and coal-fired plants during periods of low wind, MidAmerican stated.
Wright added: "Wind XII is a clear demonstration of our commitment to and investment in the cleaner, more sustainable energy future our customers want and our environment deserves.
"We have been able to invest in renewables while at the same time keeping electric rates affordable for the long-term."
MidAmerican is also building the Wind XI project – a 2GW cluster, also in Iowa.
Vestas signed a conditional agreement to supply up to 1,000 turbines for Wind XI in 2016, but Siemens Gamesa announced a 30-turbine order for the project in April 2018.