As per the deal reached with other parties in February 2013, AEP had the option to retire the Unit 5 or refuel it with natural gas.

The company said due to the cost of compliance with environmental regulations and current market conditions, it is unlikely to make the capital investment to refuel the unit.

AEP expects to record a non-operating, pre-tax impairment charge for Unit 5 of about $150m to $170m in the second quarter of 2013.

The company has already revealed plans to shut down units one through four at Muskingum River by the end of 2015.

AEP previously announced plans to retire 2,538MW of coal-fueled power plants in Ohio and West Virginia by the end of 2015, while the latest addition of the fifth unit at Muskingum River brings the total value to 3,123MW.

The company said the remaining 10,725MW of AEP Ohio will consist mostly of low-emitting, fully controlled coal-fueled plants, natural gas-fueled combined cycle and combustion turbines, and a small hydro plant.