The utility – a division of Warren Buffet's Berkshire Hathaway group – said it is filing a request with the Iowa Utilities Board (IUB) to build Wind XI, a 2GW cluster of projects.
The project locations are still being evaluated, said a MidAmerican spokeswoman.
MidAmerican has asked the IUB to approve its request by mid-September so that it can take full advantage of the extended production tax credit.
MidAmerican has previously favoured Siemens turbines at its projects, although has also used GE and Vestas in the past. It plans to start construction this year and complete the 2GW by year-end 2018.
Wind XI will result in 85% of MidAmerican's customers' electricity coming from renewables.
The cluster will also put Iowa on track to be the first US state to generate more than 40% of its electricity from wind – far ahead of any other state. Currently, it is the only state to generate more than 30% from wind.