Coal quality, composition of stack emissions, and coal combustion
byproducts have become major environmental concerns
as the rate of coal utilization increases, especially with regard to
meeting the requirements of the 1990 Clean Air Act Amendment.
With increasing emphasis on environmental issues, information
on the quality of coal (which includes ash yield, sulfur content,
calorific value, and major-, minor-, and trace-element content)
has become almost as important as information on the quantity of
the resource.