The new gas plant is equipped to generate energy to benefit 2.5 million customers in South Carolina and North Carolina.

Duke Energy chairman, president and CEO Lynn Good said: “Highly efficient natural gas plants – like W.S. Lee – are helping us deliver a cleaner, smarter energy future for our customers.

“South Carolina is important to Duke Energy, and new investments like this further our commitment to power this community with reliable, affordable energy – while continuing to be a partner that’s helping prepare the region for future growth.”

At the W.S. Lee Station, which was commissioned in 1951, Duke Energy also operates an 180MW natural gas boiler and two dual-fuel 42MW simple-cycle units.

About 100MW of the unit’s energy capacity is being sold to North Carolina Electric Membership under an agreement signed earlier.

In 2014, two coal-fired units at the W.S. Lee Station were closed while the third coal unit has been converted to natural gas in 2015.

Duke, which currently no longer operates any coal plants in South Carolina, started construction of the $700m gas plant in March 2015.

Fluor serves as the engineering, procurement and construction contractor for the combined-cycle natural gas plant.

The project created more than 600 construction jobs in addition to providing about $12m in work to local subcontractors.

Construction of the natural gas plant is part of the firm’s effort to modernize the fleet, maintain a diverse fuel portfolio, manage costs and provide reliable clean energy to its customers.

Ghartey-Tagoe earlier said: “Investing in a smarter, more efficient energy future through projects like the new W.S. Lee plant is more than just good business – it’s an investment in our state that helps attract jobs and industry and make our economy and communities stronger.”