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The major problem relative to direct firing of coal concerns transportation to the plant site. Unit trains are satisfactory to a point; however, the amount of coal that can be burned becomes self-limiting as available land for process units is used for coal yards, train switching trees, etc. Slurry pipelines could be one answer to this problem. Grass-roots sites for petrochemical complexes in themselves are hard enough to find, but that factor, coupled with sites for a nuclear package, may be an insurmountable obstacle. Siting/ EPA/ AEC restrictions must be resolved before any serious investigations of the use of nuclear energy are warranted. Except for direct firing of low-sulfur coal, none of the systems presented in the study are developed to the extent required for full-scale "commercial" operation. At this point in the study, it appears that the following systems should rate the highest priority for research and development efforts: 1. Near term (alternate fuels): stack-gas scrubbing; coal pyrolysis-char for boiler fuel and/or liquid or gas for process heaters; and fluidized-bed combustion. 2. Intermediate term (alternate raw materials):,solvent-refined coal; lower cost process for producing
gas from coal coupled with a combined cycle for improved efficiency; process heat reactors using HTGRs; and small PWRs.
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