Earth & Energy

Duke Energy can do more to recycle ash, panel reports

Workers pump a concrete mixture being used to reinforce a stormwater tunnel being built beneath East Morehead Street in Charlotte.
Workers pump a concrete mixture being used to reinforce a stormwater tunnel being built beneath East Morehead Street in Charlotte. mhames@charlotteobserver.com

Duke Energy and state policy makers can do better than bury coal ash in the ground, says a new report by the state Coal Ash Management Commission.

Legislators last year called for the commission to report on ways to make use of the 108 million tons of ash soaking in 32 ponds across the state. Ponds have spilled ash into the Dan River, leaked into waterways and probably contaminated groundwater.

Parts of Europe and Asia recycle much more ash than the United States, the report says, and North Carolina lags many states.

“To date, none of the key stakeholders in North Carolina have shown significant leadership in promoting sustainable beneficial uses of coal ash,” it says.

The commission sees potential in structural fills, which use ash to prepare uneven ground for construction. Asheville’s airport is using Duke ash as the base for a new runway.

But its greatest promise, the report says, is in replacing Portland cement as an ingredient in concrete. The problem with Duke’s ash is that it contains too much carbon to be usable.

Ash can be reprocessed to reduce its carbon content, but the report says Duke has been unwilling to guarantee a long-term supply to ensure processors can recoup their investments in equipment.

Duke used only 30 percent of the ash it produced last year in concrete and structural fills.

Duke “will need to make a commitment to transforming both production and impounded coal ash into a form where it can be beneficially reused if we are to materially expand the market for sustainable beneficial use applications,” the report says.

Duke sees significant potential in growing ash recycling markets, said spokeswoman Catherine Butler.

“We continue to explore technologies for our operating plants that would help to decrease the carbon content of ash currently generated (versus ash already stored in basins) and make it more suitable for recycling,” she said.

Butler said Duke is evaluating proposals for technology to reduce carbon in ash at its Marshall power plant on Lake Norman.

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