The company is considering selling or closing 136MW unit 1 at the Bay Shore power plant in Oregon, Ohio by October 2020.

FirstEnergy has already decommissioned units 2-4 at the Bay Shore facility in 2012 based on the impact of environmental rules.

Additionally, it plans to close or sell units 1-4, each with 180MW of capacity, at the W.H. Sammis Plant in Stratton, Ohio in May 2020.

However, units 5 to 7 at the W.H. Sammis plant will continue to provide 1,490MW of reliable baseload generation.

FirstEnergy Generation president Jim Lash said: "We have taken a number of steps in recent years to reduce operating costs of our generation fleet.

"However, continued challenging market conditions have made it increasingly difficult for smaller units like Bay Shore and Sammis Units 1-4 to be competitive.  It's no longer economically viable to operate these facilities."

The power generation units considered for closure have contributed about 4% of the electricity produced by the company's power plants in 2015.

The plant deactivations, however, will be subject to review for potential reliability impacts by PJM Interconnection, the regional transmission organization.

FirstEnergy plans to exclude these units from the PJM capacity auction to be conducted between 2020 and 2021.