Duke steam site takes shape
Published 12:00 am Wednesday, May 25, 2011
By Emily Ford
SPENCER — Duke Energy will fire the new combined cycle power plant at Buck Steam Station for the first time in August.
Commercial operation at the $600 million facility, called “combined” because it uses both natural gas and steam to create electricity, should begin in December, officials said Tuesday. The two remaining coal-fired units at Buck Steam are scheduled to be shut down by 2015.
“This tells the story about how Duke Energy has evolved,” said Duke Energy District Manager Randy Welch, standing between the soon-to-be-eliminated 1925 coal-fired units and the 21st-century combined cycle technology rising on the site.
Nineteen Buck Steam retirees took a close-up look at the new plant Tuesday, which is still under construction. They gathered under crackling power lines while Todd Shuping, project director for construction, pointed out details and probed their memories.
“How many of you swam in frog pond?” Shuping asked about a nearby swimming hole.
Many of the men worked with Shuping’s father, Doug Shuping, who also retired from Buck Steam.
Like Todd Shuping, Brent File comes from a Buck Steam family. File will run the new facility and is the son of longtime Buck Steam employee Norman File, who was on site Tuesday.
“I think it was important for them to see that Duke will still be a big presence in this community,” Todd Shuping said.
Duke, which is building the new plant in response to tighter pollution controls, shut down coal-fired units 3 and 4 last week as a condition to build the new combined cycle plant.
Coal-fired units 1 and 2 at Buck Steam were shut down years ago, and units 5 and 6 are slated for closure in 2015.
Overall, Duke will retire 1,000 megawatts of power produced with coal over three years, Welch said.
Because it will use ambient air to cool the steam instead of river water, the new plant will consume less than 5 percent of the water that was used at units 3, 4, 5 and 6 combined.
The construction crew building the combined cycle plant has peaked at about 900 workers and will begin to decline this summer.
About 25 people will work at the new facility. Welch said so far, no one has lost a job due to shutting down coal-fired plants.
The 620-megawatt natural gas-fired, combined-cycle generating plant will replace about 370 megawatts of coal-fired capacity by 2015, said Erin Culbert, a Duke Energy spokeswoman.
Actual emissions of nitrogen oxide will be reduced by 97 percent, from 2,552.9 tons per year to 64 tons per year, Culbert said.
Sulfur dioxide will be reduced essentially by 100 percent, from 10,693.5 tons per year to fewer than 5 tons per year, she said.
In 2008, Rowan County approved Duke Energy for an incentive to expand Buck Steam Station. Starting in 2012, the company will receive roughly $840,000 back from its property tax payment annually for 10 years.
The expansion was competitive, and Duke Energy considered several locations, Welch said. Incentives helped Rowan County win the project, although the availability of power transmission, natural gas and a water source were more important, he said.
“For Rowan County, this means a $600 million investment added to the tax base,” he said.
Duke Energy paid about $1.2 million in property taxes in 2010, and the company’s tax bill is expected to top $2 million when construction at Buck is complete. After 10 years, the county keeps 100 percent.
The new combined cycle facility is an intermediate load plant, meaning Duke will use it when the demand for electricity increases. Nuclear power plants, which make up 50 percent of Duke’s fleet and are the most efficient source of electricity, run around the clock, Welch said.
When demand increases, Duke uses intermediate load plants. The combined cycle plant will compete with coal-fired plants located throughout the Carolinas as the next source of power after nuclear.
Whether the plant is used on any certain day depends on the weather, demand and the cost of natural gas, Welch said.
Shaw Group is the general contractor.
Duke is building a nearly identical combined cycle plant at Dan River Steam Station in Rockingham County.
Duke Energy built an extra bay in the 230,000-volt switchyard to accommodate the additional power generated by the new plant.
Buck Steam plant was Duke Energy’s first large capacity coal generating plant built in the Carolinas and was named for the company’s co-founder, James Buchanan “Buck” Duke.
Contact reporter Emily Ford at 704-797-4264.
By the numbers
Statistics on the Buck Combined Cycle Plant convey its scale:
• 60,000 cubic yards excavation and backfill.
• 25,000 cubic yards of concrete.
• 177 miles if power cables.
• 83 miles of instrument and control cables
• 5.6 miles underground piping.
• 2,000 tons of structural steel.
• Engineering 99 percent complete.
• Construction 73 percent complete.
• Commissioning began in January.
• First fire scheduled for August.
• Commercial operation will begin in December.
• Final completion in April 2012.
How it works
A natural gas combined cycle generating facility combines two energy production processes — gas turbines and a steam turbine — to convert natural gas to electricity.
First, natural gas is burned in two combustion turbines to produce mechanical power that is converted to electric power by the generator.
For increased efficiency, the hot exhaust gases from the natural gas combustion process are then routed through the heat recovery steam generator (boiler), which produces steam and additional electricity through a steam turbine.
Combined cycle plants’ operational flexibility are key in supporting intermediate electricity demand, and their systematic use of heat released from the natural gas combustion allows them to achieve high thermal efficiency.