MidAmerican Energy Co. says it received regulatory approval to upgrade hundreds of its older wind turbines in Iowa.

The plan would enable the company to repower around 475 megawatts of wind-generating capacity to make the turbines more efficient and productive.

Many of MidAmerican Energy’s older General Electric wind turbines will be retrofitted with newer, more efficient components, including longer blades, to extend the life of the turbines.

In 2021, when both its repowering and 2,000-megawatt, $3.6 billion Wind XI projects are complete, the company says it expects to generate renewable energy equal to 95 percent of its Iowa retail customers’ annual use.

MidAmerican Energy says it has entered into agreements with GE to complete the wind farm upgrades.

Beginning in 2017, wind turbines will be repowered at the 200 MW Century wind farm in Wright and Hamilton counties, the 99 MW Victory wind farm in Crawford and Carroll counties and the 175.5 MW Intrepid wind farm in Buena Vista and Sac counties. Additional work sites and schedules will be announced at a later date.