DES MOINES, Iowa (AP) — An Iowa-based utility is proposing a massive wind turbine project that would be the nation's first investor-owned electric utility to generate all of its customer demand from wind energy.

Des Moines-based MidAmerican Energy said Wednesday that it's submitting its proposal for a $922 million wind project to the Iowa Utilities Board. The utility says the project would generate 591 megawatts of power, or enough electricity to power 2.4 million homes.

If approved, the proposal would mark MidAmerican's 12th wind project.

MidAmerican is a subsidiary of Warren Buffett's Berkshire Hathaway. It already has 2,189 wind turbines on 27 wind farms in Iowa, producing 4,400 megawatts of power.

If the latest project is approved and completed, the utility's total investment in wind will total more than $12 billion. The project is slated for completion in late 2020.