U.S. power plants burned 870 million tons of coal in 1996, leaving about 100 million tons of ash to be disposed of. Only about a quarter of that was recycled, according to the Electric Power Research
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/utilities-recycle-their-sludge-profit
[2] http://admin.indiaenvironmentportal.org.in/category/thesaurus/energy