DES MOINES, Iowa (AP) — MidAmerican Energy is still considering building a new nuclear power plant as part of its long-term plans in Iowa.

The Des Moines Register reported (http://dmreg.co/Y33BIP ) that MidAmerican President William Fehrman told state regulators the utility may try to build a nuclear plant at some point.

MidAmerican is converting coal plants at Council Bluffs and Sioux City to natural gas and has invested heavily in 2,200 megawatts of wind power capacity.

But Fehrman said he wants to make sure the company has a mix of fuels, and he's not convinced that natural gas will remain as cheap as it is now.

"I'm agnostic on the fuel issue," Fehrman said. "But what we need is a diverse mix. It's not a good idea to put too many eggs in one basket."

Fehrman said the prospects for natural gas could change if restrictions are imposed on the hydraulic fracturing process used to extract much of the nation's natural gas.

The utility, which is owned by Warren Buffett's Omaha, Neb., based Berkshire Hathaway Inc., will provide more details of its plans this summer in a report to regulators.

MidAmerican already said last month that it would stop burning coal at seven power plants in Iowa and restrict emissions from two other coal plants.

"Coal's days are numbered here in Iowa," Pam Mackey Taylor, Iowa chapter energy chairwoman of the Sierra Club, said.

MidAmerican said it will stop burning coal in two boilers at Council Bluffs and two boilers in Sergeant Bluffs by April 2016, and is evaluating whether to convert the plants to natural gas before that 2016 deadline. The company said it also will convert three coal-fired boilers at its Bettendorf facility to natural gas.

MidAmerican unsuccessfully lobbied the Iowa Legislature over the past two years to pass a bill that would encourage development of nuclear power. Consumer advocacy groups and environmental risks opposed the idea.

Iowa has just one nuclear power plant, which went online in 1975.

MidAmerican is Iowa's largest utility. It serves 732,000 electric customers and 714,000 natural gas customers in Iowa, Illinois, Nebraska and South Dakota.