Conclusions and Recommendations - Coal Waste Impoundments: Risks, Responses, and Alternatives - page 153

ALTERNATIVE TECHNOLOGIES
Coal waste impoundments are part of the system for mining and
processing coal to produce energy. In order to assess alternatives, the whole
system of mining, preparation, refuse disposal, transportation, and power
generation should be explored through an in-depth life-cycle assessment,
including cost assessment, with the goal of optimizing the system to generate
less fine coal waste while maintaining the performance and economics of the
system. The committee recommends that the total system of mining,
preparation, transportation, and utilization of coal and the associated
environmental and economic issues be studied in a comprehensive manner
to identify the appropriate technologies for each component that will
eliminate or reduce the need for slurry impoundments while optimizing the
performance objectives of the system. The committee concludes that a similar
analysis of the waste use and disposal technologies that make up the coal
system would have value. The committee recommends incorporating life-
cycle assessment of the costs and environmental impacts of the alternatives
to evaluate them on a more objective, comprehensive basis. In addition, a
detailed analysis of the economic and environmental impact of the various
policy alternatives should be performed.
The opportunities for reducing slurry volume include mining alternatives
and coal processing alternatives. However, modern methods of surface and
underground coal mining offer only a limited possibility for quality control
during mining. Slurry volume can be reduced by improving fine coal recovery,
minimizing the mass of solids for disposal, and dewatering. Many dewatering
technologies are currently available for specific applications, though none is
likely to be universally applicable. The committee believes that the research and
development currently being performed by equipment vendors will lead to
improvements in these technologies.
Slurry refuse can be utilized directly for power generation, either in
conventional boilers or in advanced combustion and gasification technologies,
some of which can reduce coal-cleaning requirements. But, the use of low
quality coal feed may increase the amount of waste generated at the power
plant. The utilization of fine coal waste in conventional coal-fired power plants
offer near-term opportunities for the reduction of fine coal waste disposed of in
impoundments. However, the coal produced is more expensive than cleaned
coal, as a result of capital and operating costs of additional equipment, and, in
the case of coal water slurry, the additional cost of transportation. To compare
technologies, the avoided costs of slurry impoundments must be included in a
cost comparison.