Energy – that's what MidAmerican is all about. MidAmerican Energy, Iowa’s largest energy company, is strategically located in the middle of several major markets in the Midwest. Headquartered in Des Moines, Iowa, the company provides service to customers in a 10,600-square mile area in Iowa, Illinois, South Dakota and Nebraska. MidAmerican Energy is a subsidiary of Berkshire Hathaway Energy.  At MidAmerican Energy, our commitment to you, the customer, is to deliver the exceptional personal service you deserve. If you aren't satisfied, neither are we. That's a promise. If you have ideas about how we can better serve you or have a problem that has not been resolved to your satisfaction, call us at 888-427-5632 or email us.  Our Generation Mix. At the end of 2015, MidAmerican Energy had 8,535 megawatts of owned generating capacity. Approximately 37 percent was fueled by coal; 41 percent by wind; 17 percent by natural gas and oil; and 5 percent by nuclear, hydroelectric and other.