Concrete makers look to import coal ash

Trucks load up with concrete mix at the Concrete Supply facility on Metromont Rd. in north Charlotte in this file photo. The silo on the left contains fly ash, an ingredient of concrete.
Trucks load up with concrete mix at the Concrete Supply facility on Metromont Rd. in north Charlotte in this file photo. The silo on the left contains fly ash, an ingredient of concrete.

As Duke Energy ships coal ash across the Piedmont to dump it in a former clay mine, Charlotte’s largest concrete company is negotiating to buy ash in Asia.

Ash, the focus of a statewide cleanup that Duke estimates will cost $3.4 billion, is a coveted ingredient for concrete makers. Despite the 157 million tons in ponds and landfills across the state, the industry says it can’t secure enough ash in Duke’s home base.

“They’re proceeding with the cleanup but they’re really not pursuing a strategy to put it in the hands of somebody else, other than put it in the ground,” said Henry Batten, president of Charlotte’s Concrete Supply Co.

Duke says it is producing less ash as it shuts down coal-fired power plants, but it is recycling a larger proportion of it. The company says it wants to increase reuse of ash but also faces state and federal deadlines to close its ash ponds.

Replacing Portland cement with fly ash as an ingredient strengthens concrete needed for heavy-duty applications such as building bridges, roads and tall structures.

But the design of Duke’s power plant boilers, and the use of “scrubbers” to reduce air pollutants, results in ash with too much carbon to be usable in concrete.

Utilities in South Carolina get around that by reprocessing ash to reduce carbon content. Duke flirted with that idea for its Marshall power plant on Lake Norman, but now says the idea is not economical because its coal units are operating less.

“We prefer to make investment decisions about installing technology at other sites after the state’s basin classification process is complete and we have more clarity on the path forward for closure options,” Duke said in a statement.

A study of recycling markets and technologies, commissioned by Duke, is expected to be completed by the Electric Power Research Institute by mid-year. Duke says it continues to solicit recycling technologies, but few of the 180 proposals received have been shown to work at industry scale.

Concrete makers complained about stingy ash sales in 2014, as legislators debated ash policies following Duke’s spill into the Dan River. Two years later, they say the situation has worsened.

Concrete Supply needs about 20 loads of ash a week, Batten said, but can obtain only seven to eight loads from Duke’s Belews Creek and Roxboro power plants. That’s down about 20 percent from two years ago.

“I don’t understand how they can rationalize that what they’re doing is in the best interests of the environment or ratepayers,” Batten said.

Nearly 46.5 million tons of fly ash is expected to be needed to make concrete in the Carolinas and Virginia over the next 15 years, according to a recent study for the Carolinas Ready Mixed Concrete Association.

The N.C. Utilities Commission reported in January that utilities lose money – up to 30 cents a month are passed to Duke’s N.C. customers – by selling ash, in part because of the high hauling costs. But consumer costs would rise even higher, the report concluded, if ash is stored only in surface impoundments.

Duke cited N.C. Department of Transportation restrictions on the amount of ash that can be used in concrete, according to that report. Duke added that long-term commitments to sell reprocessed ash have been hard to find.

The now-defunct Coal Ash Management Commission touted ash recycling in a report last year. Former chairman Michael Jacobs wrote the legislature’s Environmental Review Commission this month to again urge changes so ash could be reused instead of simply buried.

“We fully expect that at some point in the the years to come, most stakeholders will wish that we had been more aggressive in promoting recycling options,” Jacobs wrote.

Bruce Henderson: 704-358-5051, @bhender