There are more than 600 coal-fired power plants in the U.S.,
all of which must find storage for the ash that comes from
burning coal. At most plants, the thick dust ends up in
large ash ponds. Accidents can be disastrous. In late
December 2008, one of the holding tanks at the Kingston
Fossil Plant in Harriman, Tennessee collapsed, spilling wet
coal ash as far as the eye could see. Several homes were
destroyed but longer lasting was a contamination of the
local Tennessee River, killing wildlife and depositing high
levels of mercury into the land and water.