Iowa, which already gets more of its power from wind than any other U.S. state, will become more reliant on the electricity source under a $3.6 billion plan announced Thursday by a utility owned by Warren Buffett’s Berkshire Hathaway Inc. MidAmerican Energy Co. said Thursday that it is planning to build up to 2,000 additional megawatts of wind turbines with a goal of generating 85% of its power from wind. The company, based in Des Moines, will use renewable-energy tax credits that Congress extended last December to make the project economically feasible, said MidAmerican Chief Executive Bill Fehrman. “Because of the tax credits and our ability to deliver these projects at a low cost, we’re setting up our customers for a low-carbon future,” Mr. Fehrman said in an interview. “Whatever happens with carbon regulations…we will be able to meet those requirements without additional costs for customers.” Thirty-one percent of the power in Iowa is now generated by wind, more than in any other state, according to the American Wind Energy Association, an industry group. MidAmerican’s new project would boost wind’s share to 40%, according to the state.