The company announced that its 316-megawatt thermal power station near Moncure, North Carolina and its 177MW unit outside Hartsville, South Carolina will be retired at the beginning of October.

Both plants will remain online through the rest of the summer season to help meet heightened electricity demand associated with air conditioning.

The move represents an acceleration in the utility’s scaling back of coal-fired stations as the Moncure unit wasn’t originally intended to close before 2013.

Closing of the Hartsville station will mark the end of Progress’ coal-fired operation in South Carolina.

“These plants and especially the men and women who have operated and maintained them have played a vital role in meeting customer energy needs reliably and affordably for decades,” Duke energy supply executive vice president Jeff Lyash said.

“As we continue modernizing our generation system, we salute those who have been instrumental in fueling our region’s economic growth so dependably.”

Duke said the decision to take the plants offline was made due to pending changes in environmental regulations and the anticipated early 2013 commercial operation of new gas-fired generation near Goldsboro, North Carolina.

Continued low gas prices and the cost of adding emission controls on small units were also listed as contributing factors.

Progress said it would continue to operate its Roxboro, Mayo and Asheville coal-fired plants in North Carolina even as the company’s own modernization plan indicated a progressive switch to gas facilities.