Lee Steam now running on natural gas

Lee Steam Unit 3

Initial Web Post (A revised version of this article was posted Apr. 15)

 By David Meade

An innovative project to retrofit a 57 year old coal fired steam turbine at Duke Energy’s W. S. Lee Steam station near Williamston has recently been completed. When the plant was placed into operation in 1951 it was one of the most modern and efficient power plants Duke Power had constructed. It was also innovative and engineered looking to the future.

The plant was constructed with three coal fired steam turbine units and was designed so that it could be converted to gas one day. Fifty-seven years later that day has arrived.

The original Lee Steam plant began generating electricity with one steam driven turbine unit when the plant opened in 1951. A second unit was added and placed into operation the next year.

Unit 3, the newest turbine located inside the original plant, was installed and operating by 1958.

All three of the original units relied on steam which was produced in a massive boiler system fired by coal.

When the upgrade converting the Lee Steam Station from coal to gas began in Oct. 2014, Units 1 & 2 were retired and on Nov. 4, 2014, the facility was retired as the last coal fed plant in South Carolina. However Unit 3, (pictured above) continues to provide electricity to the nation’s power grid.

The upgrade included new gas supply lines and other necessary equipment including digital monitoring to transformed the facility from coal to natural gas. In addition to repurposing Unit 3, the upgrade project kept the existing boiler, pumps and other support equipment.

The conversion process was $75 million less expensive than replacing the remaining turbine unit with a new combustion turbine.

“This project is like converting your garage into a family room,” Duke Energy spokesperson Lisa Parrish said. “The basic structure was already there making it less costly than building a new wing onto your house.”

Gas is supplied from a nearby supply pipeline.

Specialized gas detection systems were installed throughout the plant along the gas piping to protect the equipment when it is in operations. New LED explosive proof lighting was also installed.

Repowering the current plant to use natural gases cut greenhouse gasses making it more environmentally friendly, Parrish said. By using natural gas instead of coal, all sulfur dioxide emission have been eliminated.

The nitrogen oxide emission rate has been cut by 550 percent.

Lee Steam’s Unit 3 has a quick start up and can power on faster than traditional coal or nuclear plants, providing greater operating flexibility, Parrish said.

Total cost for the upgrade project was $22 million. A new combustion turbine plant would have cost more than $95 million.

Currently the plant provides enough electricity to power 122,000 homes in the area. Unit 3 has a life expectancy of 10 years a spokesperson said.

But Duke continues to look to the future, and with a nearby gas supply line and room for expansion at the existing Lee Steam site, the company is investing in a completely new combined cycle facility.

The new W. S. Lee Natural Gas Combined Cycle Facility will rely on natural gas and will be extremely efficient. The new plant facility will be a 750-megawatt natural gas-fired combined cycle plant and will employ 40 fulltime, well paying jobs.

More than 500 workers are expected to be involved in construction which is expected to begin in June and take approximately three years to complete.