A new day for coal ash recycling

 

Amy Gahran | Aug 11, 2015

The coal ash recycling industry went into a tailspin after a major 2008 spill at a TVA plant in Kingston, Tenn., prompted the EPA to question whether coal ash should be treated as hazardous material. Last December, however, the EPA relented, to a point anyway. As a result, recycling of coal ash now appears to be coming back to life. 

Utilities earn millions of dollars in the recycling market. Duke Energy, among others, has a keen interest in making more of its coal ash available for recycling. Across its operations in six states, Duke produced 3.5 million tons of coal ash in 2014 - over half of which was generated in North Carolina. The company reused 47% of its total ash.

"When EPA reaffirmed coal ash as nonhazardous, the interest in reusing ash spiked - and this will continue," predicted Catherine Butler, a spokesperson for Duke.

While the EPA handed the industry a victory in that issuing that determination late last year, it did decide for the first time to regulate the storage and disposal of the estimated 140 million tons of coal produced by utilities every year. States traditionally regulated coal ash impoundments with standards that varied widely.

Now, to get a clearer picture of the opportunities ahead, Duke recently announced that the Electric Power Research Institute will be conducting a study of the market and technology opportunities for coal ash recycling in North Carolina.

Beyond generating additional revenue for the utilities, selling coal ash can help relieve the mounting costs, complexities and liabilities of storing and disposing of large volumes of coal ash.

Duke is especially under pressure from the state of North Carolina to clean up its old coal ash storage ponds. 

In February 2014, 82,000 gallons of coal ash leaked into the Dan River from a storage pond at a retired Duke power plant in Eden, N.C. Later that year, the state passed the North Carolina Coal Ash Management Act, which required Duke to phase out some existing coal ash storage ponds and to update its coal ash management practices. The EPRI study was required by this legislation.

"We have very aggressive deadlines based on state law to excavate some ponds and close other ponds," said Butler. "But we also have over 110 million tons of ash in basins throughout our operating and closed facilities in six states. We're hoping to find more ways to reuse that ponded ash."

The catch is that, with current technology, old, wet coal ash stored in ponds isn't easy to reuse. Its primary reuse option is as "structural fill" material, to build up land to support large construction projects. For instance, Duke is sending some ash from its old ponds to projects around North Carolina, such as reclaiming open-pit clay mines and new runway construction at a municipal airport.

"Structural fill is a good way to reuse a large amount of ash in a tight time frame. And in North Carolina, Duke is faced with aggressive deadlines," said Butler. "We're required to excavate ash at three facilities by August 2019 and another by 2022. We have to remove that ash from the ponds and put it into a fully lined solution."

Meanwhile, Duke is implementing dry storage for all of the coal ash it now generates ("production ash"). This offers far greater opportunities for recycling given existing technologies.

Dry coal ash (a term that covers several coal combustion products, but mostly fly ash and bottom ash) has a wide variety of possible uses, mostly in the construction industry. Since the 1980s, coal ash has been a popular ingredient of cement. It can also be used to make synthetic gypsum for wallboard, roofing shingles, ceiling tiles and other building materials. 

"There's probably coal ash in the wallboard in your home," said John Ward, spokesperson for the American Coal Ash Association. 

Coal ash also can be used in a wide range of other products - from bowling balls and tool handles to utility poles and marine pilings.

But expanding the technological options for Duke and other utilities is a big motivation for the EPRI research. 

Ken Ladwig, EPRI's technical executive in charge of the project, explained the study has three components:

1. Market study, to assess available markets for Duke's coal ash in North Carolina. (Butler noted that transportation costs significantly affect recycling economics, so Duke is focusing on recycling opportunities within a 100-mile radius of existing coal ash basins.)

2. Conversion technologies, to enhance the quality of ponded and production ash so that it can more easily be reused with current technologies. 

3. Innovative and game-changing end uses for recycled coal ash. For instance, geopolymers are an alternative structural material that could replace cement in many instances. "There are companies manufacturing geopolymers today, but they don't yet have a strong market presence; the entire construction market is geared toward concrete," said Ladwig. "Expanding the manufacturing capacity and market for geopolymers will require new equipment and process - specialized, but potentially very high volume."

The innovative (and potentially disruptive) uses of recycled coal ash intrigue Duke. "We produce much more ash in North Carolina than the concrete market here is looking for," said Butler. 

As might be expected, the principals of supply and demand play a role in any kind of recycling - but in coal ash recycling, direct compensation may not be the biggest part of the bottom line. 

Utilities probably won't earn significant revenues from selling coal ash for reuse. However, recycling as much ash as possible can substantially reduce their waste management costs, as well as offset costs for legally mandated remediation of ash ponds.  These savings can be passed on to ratepayers and shareholders. 

On the demand side, the construction industry is facing growing pressure to reduce greenhouse gas emissions from cement kilns. Since coal ash has already been burned, it reduces emissions for cement manufacturers, compared to cement made with other materials. The cement industry has long been a major source of greenhouse gases and is facing mounting pressure to cut emissions.

The EPA's determination last year that coal ash is not hazardous was, of course, welcome by many.

"In 2000, when the Clinton Administration gave its approval, 29.5% of coal ash in the U.S. was recycled," said Ward. "Over the next eight years, that increased to 44.5%. But after the 2008 Kingston spill, when EPA revisited whether coal ash was hazardous, that made everyone in the industry nervous. 

"EPA took six years to resolve this, and during that time, recycling markets languished. Now we can move forward again, with regulatory certainty again.

"The irony was that while we were debating how to regulate coal ash, the disposal problem increase. If we'd kept recycling at 2008 volumes, we'd have landfilled 30 million fewer tons of ash," Ward said.

EPRI expects to finish and submit its research to Duke by next May. Shortly afterward, Duke must submit its report (including that research) to the North Carolina Coal Ash Management Commission - which will make it a public record, available to the utility industry, environmental advocates and other interested parties.

Duke recently asked a federal judge to dismiss or delay a lawsuit by environmental advocates over coal ash contamination at its Buck power plant in Salisbury. The company pleaded guilty earlier this year to nine violations of the federal Clean Water Act and was to pay $102 million in fines and restitution for illegally discharging pollution from coal-ash dumps at five of its North Carolina power plants.

http://www.energybiz.com/article/15/08/new-day-coal-ash-recycling