Coal Ash Plant

Power generation from Kentucky coal supports industry and advances economic development, but it also carries some environmental and economic negatives. Efforts to reduce air pollution have, themselves, added to power generation residues. Kentucky’s many coal-fired power generation plants produce huge amounts of coal ash of various sizes. This ash is unsightly at best and requires ever greater amounts of land for storage.

The Advanced Coal Ash Processing Plant initiative, led by Thomas Robl and John Groppo of UK's Center for Applied Energy Research, is an effort to mitigate these coal-burning negatives and turn them to economic positives.

Development and Installation of an Advanced Coal Ash Processing Plant

A demonstration project at the Ghent Power Plant in Carroll County, Kentucky, is being tested to determine its ability to turn mountains of coal ash into commercially competitive products, including some that will make concrete stronger and more durable, reduce coal power generation costs, remove ash piles, and create new jobs for Kentuckians.

The project is implementing a system at Kentucky Utilities' Ghent Power Plant to improve the quality of fly ash from coal burned to generate electricity. The higher-quality fly ash then can be used in concrete as a partial replacement for Portland cement, thereby creating a cement of greater durability and strength. This project offers both a new use for coal ash waste and makes coal-burning for electricity-generation more economical, providing a boost for states like Kentucky where coal mining is a major industry.

Actions and Outcomes to Date

Working with the U.S. Department of Energy’s Clean Coal Power Initiative, Louisville Gas and Electric, Cemex, Charah, the Kentucky Science and Engineering Foundation, and the East Kentucky Power Cooperative, the UK team has demonstrated UK’s multi-product ash separation technology for making coal ash into usable, commercially saleable products. Two trailers carrying the UK pilot ash separation plant were moved onto the site at the Ghent Power Plant, and four processes were studied and tested—primary hydraulic classification, spiral separation/concentration, secondary classification, and froth flotation—each progressively sorting out ever finer coal ash. (See photos and descriptions on coal combustion by-product processing at the CAER website at: http://www.caer.uky.edu/coalash/research/research.shtml.) Most valuable is the ash size produced by secondary classification, using UK’s patent-pending technology. Testing was done to produce by-products in each size range and to provide information for scale-up and economic evaluation. Field testing was completed in May 2006, with 94 tests having been run.

Testing showed that a very high quality product could be delivered via secondary classification, with high yields and recoveries. Factors for scaling-up the process to commercial volumes were within a practical range. Products from the process were found to have good reactivity in mortar and concrete products. With field testing complete, final engineering design can go forward.

UK is now engaged in collaborative development efforts. The first of these is a joint research and development project with the University of Dundee (Dundee, Scotland) Civil Engineering Department. This project will evaluate the effectiveness of CAER’s ash technology on coal combustion ash produced in Great Britain. Pilot studies are processing ash from sites throughout Britain for evaluation as Portland cement replacement products to meet British construction specifications. The second is a licensing agreement signed between UK and a joint venture company comprised of MCC Technologies (New York) and Charah, Inc., of Louisville, Kentucky. The agreement uses two licensed UK ash separation patents.

The MCC Technologies/Charah, Inc. joint venture company is currently conducting market evaluations and negotiations are ongoing with coal-burning utility companies to determine potential sites for installing the first commercial-scale ash plants. A final decision is anticipated in January 2008.