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Santee Cooper's Cross Generating Station on the banks of Lake Moultrie produces energy using steam generated by burning coal.
By Molly Parker
Staff Writer
“Sixteen, please.” Giving an order laced with a Southern drawl, Bill McCall Jr. directed the elevator operator seated atop a five-gallon bucket to take him to the top of the boiler tower, a critical piece of the fourth power unit under construction at Santee Cooper’s coal-fired facility in rural Cross.
Donning hard hats and safety goggles, McCall, who is Santee Cooper’s chief operating officer, and two of his senior-level colleagues stepped out onto the open-planked structure.
From this vantage point, some 238 feet up in the air, heaps of coal below look like dark rolling hills.
Train cars bring in 10,000 tons a day of coal that is crushed as fine as baby powder and blown into a boiler that creates a hot steam — reaching temperatures as high as 1,055 degrees Fahrenheit — which spins a turbine that converts energy from a mechanical to an electrical state. It is then transmitted down three conductors to a transformer, jumped to 230,000 volts and shipped to the power grid.
It’s the means by which electricity is provided to thousands of South Carolina businesses and homes, yet all the while, these towering structures spew noxious pollutants into the air — chief among them mercury, carbon dioxide, particulate matter and sulfur dioxide — though far less than they once did.
It is these chemical emissions, an inevitable byproduct of coal-generated power, that have become central in a debate about whether Santee Cooper should build another coal plant 70 miles to the northeast near Kingsburg on 2,700 acres of wetlands and pine forest neighboring the Great Pee Dee River.
The state-owned utility expects to face a 525-megawatt shortfall in just five years without it, which Santee Cooper says will hamper the state’s ability to attract business and industry.
Santee Cooper promises that its facility, when built, will be the cleanest coal plant in the nation, perhaps in the world. That notion has been challenged by environmental groups hoping to thwart plans by convincing the state Department of Health and Environmental Control that it should not issue a permit for the plant.
“The fact that they say it doesn’t make it so,” said Blan Holman, an attorney for the Southern Environmental Law Center, which has threatened legal action as an alternative.
Environmental evolution
Some 60% of the footprint of each coal unit is made up of environmental controls. High-pressure fans suck the exhaust gas through a selective catalytic reduction process that strips it of nitrogen oxide, where it is run through a precipitator that removes particulate matter to the scrubbers.
Standing atop the Cross plant on a recent day, McCall pointed to the four massive scrubbers, one for each plant, outfitted with octopus-like metal tentacles that remove sulfur dioxide by shooting a mixture of limestone and water known as slurry at the exhaust gas waste, produced from of the combustion process.
When the first scrubber was built of steel and rubber nearly 25 years ago, it removed only 70% of sulfur dioxide, compared to the newest one made of concrete and tile that cleans away 96% of the pollutants shown to increase respiratory illnesses when present in the air.
The first Cross unit went online in 1983, the third at the beginning of this year. The fourth unit, upon which McCall stood, is still under construction.
Over the past two decades, the environmental controls have tightened and improved for coal-fired facilities, requiring less space in return for more efficiency.
The four units combined that will be running by 2009 are permitted to emit the same amount of pollution as the two older units were allowed to cough out for a decade.
“This is what you call evolution,” he said.
All the units have now been updated to remove at least 93% of sulfur dioxide before the gas heads out the smoke stack and into the environment. The new coal units near the Pee Dee River would do even better, he said, removing 97% of sulfur dioxide, McCall said.
This evolution includes turning once-buried waste into usable products. For instance, oxygen is pumped into the scrubber to create calcium sulfate, also known as synthetic gypsum.
American Gypsum, a new $125 million, 84-employee plant in Georgetown, is expected to begin operating by year’s end. The plant will take calcium sulfate generated at Santee Cooper’s Cross and Winyah generating stations and turn it into wall board.
“I feel like we’ve been a research and development lab for this industry,” McCall said.
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