Useful things rise from ashes
Coal-plant waste is recycled into building materials

By Tony Bartelme (Contact)
The Post and Courier
Wednesday, October 29, 2008
GEORGETOWN — At Santee Cooper’s Winyah generating station, powerful generators make enough electricity to light 577,000 homes. In the process, the plant creates vast amounts of ash, and for years, hundreds of thousands of tons ended up in nearby retention ponds. No more.

Today, nearly all of this ash ends up being reused. In the shadow of the Winyah plant’s smokestacks, American Gypsum recently opened a $150 million factory that uses Santee Cooper’s gypsum to crank out as much as 136 miles of wallboard per day. Nearby, crews mine bottom ash from a pond to make lighter concrete building blocks; fly ash is sent to concrete-makers.

 
Alan Hawes
The Post and Courier

The massive American Gypsum plant uses gypsum generated by Santee Cooper’s Winyah coal plant next door. When going full-tilt, the plant makes 2,500 pieces of wallboard per hour.

 
Altogether, Santee Cooper manages to reuse about 90 percent of the ash generated at the Winyah, Cross and Grainger coal-burning plants. South Carolina Electric & Gas, meanwhile, says it reuses an average of 63 percent of its coal-combustion waste. Both utilities’ recycling rates are higher than the industry average, which is about 43 percent. Both say they want to do even better.

“A lot of utilities are out there now hawking this stuff,” said Jay Hudson, Santee Cooper’s chief environmental manager. “But we probably started sooner, and by working hard, we got something going.”

The success of these recycling efforts has serious environmental and economic implications. For years, coal ash ended up in unlined landfills and ponds. Over time at some of these landfills, arsenic and other heavy metals in the ash leached from the landfills into groundwater, a Post and Courier Watchdog investigation found.

Successful recycling efforts could help reduce the need for these ash pits, though utilities also have learned the hard way that reusing ash carries risks.

‘Taking all we make’

Every year, coal plants in South Carolina generate nearly 2.2 million tons of coal ash, but one company’s waste is another’s raw material.

Fly ash, for instance, is a good substitute for cement in concrete. In fact, adding fly ash makes concrete even stronger. Roughly 330 train loads of Santee Cooper fly ash went into the new Cooper River bridge towers, which required a super-dense form of concrete. About 100,000 tons of coal ash from SCE&G’s McMeekin Station landfill was used in a concrete dam at Lake Murray.

Another benefit: Because it replaces cement, fly ash also helps reduce carbon dioxide emissions that would otherwise be released by cement manufacturers. According to the American Coal Ash Association, every ton of fly ash used instead of cement reduces one ton of carbon dioxide, equivalent to two months of emissions from a car. Fly ash also is used in paints, auto bodies, PVC pipes, battery cases, bowling balls and shower stalls.

In addition to fly ash, gypsum is another coal plant byproduct, and the Winyah Station generates about 800 tons a day, said Mitch Mitchum, the plant’s longtime manager.

In years past, the gypsum would have gone into the plant’s massive ash ponds, creating a chowder-like muck. Now, the gypsum travels through pipes to a building where vacuums dry it to a moist beige powder. From there, conveyor belts take the gypsum to the new American Gypsum plant. “They’re taking all we make,” Mitchum said.

The first thing many people notice when they step into American Gypsum’s massive factory is its cleanliness, said Steve Wentzel, the factory’s manager. Anyone who has worked with wallboard knows how dusty it gets when you cut and sand it, but the floors, railings and machinery inside American Gypsum pass the white glove test because of powerful dust-sucking vacuums.

All told, the plant takes up 650,000 square feet, or more than 11 football fields. Once the gypsum from Santee Cooper arrives, it’s remixed with water and sprayed onto a wide belt, creating a material that looks like thick pancake batter. Other machines roll recycled paper onto the mixture, creating what Wentzel described as a “gypsum sandwich.”

This sandwich dries as it moves along a continuous arrow-straight 2,000-foot-long conveyor belt. Saws then cut the wallboard into smaller sheets. The factory makes about 2,500 pieces per hour, or enough per year for 70,000 homes a year, Wentzel said.

Thanks to the wallboard plant, 84 people have jobs, and Santee Cooper sometimes trucks gypsum from other plants to keep up with demand. Santee Cooper officials weren’t sure whether their ash recycling program makes money, but they said the utility certainly is saving money that would otherwise be spent on landfills.

“We didn’t necessarily look at it as a way to make money,” said Hudson, Santee Cooper’s environmental manager. “We look at it as a way to recycle a waste product.”

Risky uses

While some utilities are turning coal ash into useful products, others have done so with disastrous results.

In the town of Pines, Ind., for instance, utilities dumped coal ash in landfills and used ash as road fill around the town, sometimes creating layers 8 feet thick. Eight years ago, residents began complaining about odd smells in their drinking water, and tests showed manganese, boron and other chemicals in coal ash had contaminated the area’s groundwater.

In Centerville, Va., a golf club used 1.5 million tons of fly ash as fill for a new course between 2002 and 2007. Now, tests in groundwater under the course show elevated levels of arsenic, chromium and lead, and nearby drinking wells have elevated levels of boron, a contaminant often found in fly ash.

Another potential hurdle for reuse: As utilities install new scrubbers to reduce air pollution, mercury and other chemicals that would otherwise go up their stacks will end up in ash. Experts with the Environmental Protection Agency say this could change the composition of the ash, making it less suitable for reuse or recycling.

“The sheer quantities that are being produced, and the fact that these materials contain a wide variety of toxic constituents is an enormous waste-management challenge,” said William Hopkins, a biologist at Virginia Tech who has studied coal ash’s effects on wildlife.

Citing the Virginia golf course situation, Hopkins said it’s important that coal ash be immobilized in some way. “That’s a wonderful thing. You save landfill space and prevent it from getting into the environment,” he said. “But you have to demonstrate that the benefits of using (ash) outweigh the risks.”

Reach Tony Bartelme at tbartelme@postandcourier.com or 937-5554.\

Information From:

http://charleston.net/news/2008/oct/29/useful_things_rise_from_ashes59514/