9 Investigates

Why can't more of Duke's coal ash be repurposed?

MOUNT HOLLY, NC — Every day, tons of coal ash are hauled away from Duke Energy's old Riverbend Steam Station in Gaston County. The electricity generating plant is retired now, but in the past, the coal-fired steam turbines were a major power producer for the region beginning in the late 1920s.

Truckloads of the coal ash from Riverbend will be recycled, but some 100-million tons remain at other Duke facilities where the plan is to cap the basins where the it's stored and leave it. Some ask why not do something else, like re-purpose it into an ingredient in concrete?

"It makes it less susceptible to like the de-icing salts that get used [on roads], less susceptible to erosion or corrosion, that's why we need it. Makes it better," explained Henry Batten, President of Concrete Supply Company in Charlotte.

Batten told us a fine, powdery, part of coal ash, called fly ash is valuable to his industry. But, the kind he can use is hard to find.

"It's been challenging for the last three or four years.  Principally, as the economy improved and construction improved, there was greater demand," he said.

So, while cities like Charlotte are enjoying a construction boom -  some say creating a higher demand for ash -  energy companies are creating less of it as they rely more on cleaner energy like natural gas or alternative energy sources.

And Batten says using the coal ash at Duke's sites across North Carolina isn't as simple as just digging it up.

"You just can't take ash from the ground and say, 'Okay mister concrete guy here is your ash.' It has to be reprocessed and reburned essentially," he explained.

Batten says ash in basins is unusable because it contains contaminants like carbon, which power plants are not allowed to send out into the air.  So, what happens?

"Stuff is going up the flu and they're trying to knock it down so less stuff goes out. Well, then they basically put all these contaminant into the fly ash," he said.

The shortage of usable ash has caused some desperate companies to turn to countries with air standards that are laxer than ours.

"In India or China there is no EPA, so they're burning this stuff really good. It's back to the way it used to be for us," Batten said.

In North Carolina, state lawmakers recently ordered Duke to start reprocessing ash in basins so it can be used for concrete - helping Duke meet its state obligation to safely close ash basins by 2029.

Duke Energy Vice President Brian Weisker told Channel 9 the company is investing in $180 million technology that reduces the amount of carbon in ash to make it usable in concrete. That work starts at facilities in Salisbury, Goldsboro, and Moncure by 2020.

Watch below: How coal ash is reprocessed.

"Where the material is going to go is going to be driven by the market," said Weisker

"I expect it will sell out the minute it opens," said Batten.

But Catawba River Keeper Sam Perkins wonders why reprocessing can't be done at other Duke facilities with much more ash.

"It's ludicrous not to jump on the opportunity to take ash from Allen, or Marshall on Lake Norman, and use that in concrete to take care of a problem," he offered.

But Weisker says it's not that simple and going that route could impact customer electricity bills. And, because of the sheer volume of ash at those sites - it could take decades to complete.

Duke Energy is working now to close all of its coal ash basins across the state by 2029. Some will be closed by excavating the ash and moving it to another site, like at Riverbend Steam Station in Mount Holly. However, most sites will be closed by safely capping the ash in place.

The company says some coal ash that it producers currently can be recycled in concrete, it just depends on the ash’s carbon content. The company says for every ton of coal ash used as a replacement for portland cement in concrete, approximately 1 ton of greenhouse gas emissions is avoided.

Duke said it recycled 63 percent of the ash produced in 2015. The company said it continues to pursue additional opportunities for recycling.