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Location
Lexington, Kentucky
Start Date
6-5-2026 2:00 PM
End Date
6-5-2026 2:30 PM
Description
A northern US power plant is preparing for the closure of 40-year-old coal ash and wet FGD (flue gas desulfurization) ponds per CFR 257.102. The pond’s contents must be dried before capping to allow heavy machinery to operate on the surface to spread the cover and liner materials. However, the high moisture content (55%) and the water holding capacity of the pond mixture, combined with a wet, cold climate, are preventing adequate drying to achieve the mandated closure dates. The US Forest Service funded this project to determine whether biochar made from waste wood can aid in ash pond remediation. Biochar is a high carbon product produced by heating biomass (>400°C) in a low oxygen environment. Preliminary research conducted at the University of Minnesota shows that adding biochar to coal ash residue at low addition rates (<10% wt.) significantly increases the drying rate of the ash, potentially allowing fast field drying of the mixture. In addition, mixing the biochar with the coal ash/FGD material significantly increased the mixture stability (shear strength) with no additional drying. Results from Michigan Tech show that biochar can also reduce the heavy metal content found in ash pond leachate. Biochar addition reduced the concentration of seven heavy metals from 9% to as high as 100% adsorption. In a coal ash landfill environment, biochar degrades very slowly, suggesting that adsorbed heavy metals could be sequestered for thousands of years. In addition, the use of biochar could reduce greenhouse gas emissions by up to 50% compared to current forestry practices. This presents an opportunity for a power plant to reduce the time required to close a coal ash pond and recoup a portion of its investment in biochar addition by applying for various carbon credits.
Document Type
Presentation
Archival?
Archival
Included in
Energy Systems Commons, Environmental Indicators and Impact Assessment Commons, Environmental Monitoring Commons, Mining Engineering Commons, Oil, Gas, and Energy Commons, Structural Materials Commons, Sustainability Commons
Increase drying rate and reduce heavy metals in legacy coal ash landfills with biochar addition
Lexington, Kentucky
A northern US power plant is preparing for the closure of 40-year-old coal ash and wet FGD (flue gas desulfurization) ponds per CFR 257.102. The pond’s contents must be dried before capping to allow heavy machinery to operate on the surface to spread the cover and liner materials. However, the high moisture content (55%) and the water holding capacity of the pond mixture, combined with a wet, cold climate, are preventing adequate drying to achieve the mandated closure dates. The US Forest Service funded this project to determine whether biochar made from waste wood can aid in ash pond remediation. Biochar is a high carbon product produced by heating biomass (>400°C) in a low oxygen environment. Preliminary research conducted at the University of Minnesota shows that adding biochar to coal ash residue at low addition rates (<10% wt.) significantly increases the drying rate of the ash, potentially allowing fast field drying of the mixture. In addition, mixing the biochar with the coal ash/FGD material significantly increased the mixture stability (shear strength) with no additional drying. Results from Michigan Tech show that biochar can also reduce the heavy metal content found in ash pond leachate. Biochar addition reduced the concentration of seven heavy metals from 9% to as high as 100% adsorption. In a coal ash landfill environment, biochar degrades very slowly, suggesting that adsorbed heavy metals could be sequestered for thousands of years. In addition, the use of biochar could reduce greenhouse gas emissions by up to 50% compared to current forestry practices. This presents an opportunity for a power plant to reduce the time required to close a coal ash pond and recoup a portion of its investment in biochar addition by applying for various carbon credits.
