LETTERS Burning coal, alternatives Dear Sir: The article “How to Make Coal Burn Cleaner” ( E S T , January 1976, p 16), is particularly timely; we in EPA are most concerned with many environmental and energy related decisions facing the power industry today. Our engineers have reviewed the several alternatives being offered to convert coal into electricity and other forms of energy. While coal gasification and liquefaction probably will have applicability to the generation of highquality fuels, we doubt that these technologies will be economically competitive with coal burning at power plants in the near future. As Mr. Train pointed out, EPA believes scrubbing to be a more practicable approach to the control of sulfur oxides at power plants. This conclusion is supported by a contract study conducted by the M. W. Kellogg Company entitled, “Comparison of Flue Gas Desulfurization, Coal Liquefaction, and Coal Gasification for Use at Coal-Fired Power Plants”, (EPA-450/3-75-047), April 1975. The report shows that flue gas desulfurization technology is more fully developed than
either gasification or liquefaction, and that it is less costly and has a smaller energy penalty. A TVA task force came to the same conclusion regarding gasification in its February 1975 report prepared for the Electric Power Research Institute, “Evaluation of Fixed Bed Low Btu Coal Gasification Systems for Retrofitting Power Plants”. Mr. David A. Tillman expresses a similar view in his article (fS&T, January 1976, p 34), at least on the energy aspects. We would have to disagree with Mr. Tillman on the environmental and economic viability of scrubbers. At this time it is difficult to estimate whether flue gas desulfurization systems at power plants will be used to produce salable by-products or throwaway sludge. Most of the new facilities will be lime or limestone systems and will dispose of the waste in landfills. Nonetheless, the possibility of producing sulfuric acid and other salable by-products should not be ignored. If a utility were to choose the sulfuric acid route, it could install a sulfuric acid plant at the site or with the Mag-ox process could ship the magnesium sulfite sludge to an acid producer. In the latter case, the
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acid producer would regenerate the sludge and return magnesium oxide to the utility for reuse. The possibility of gypsum by-products has generally been ignored in the U S . However, in Japan most of the lime/ limestone systems produce gypsum for use in either wallboard or portland cement. Gypsum is now being produced at one small prototype plant in the U S . and several vendors are offering the gypsum option for inclusion with lime/limestone systems. One US. utility has noted that it may make economic and environmental sense to oxidize the sludge to gypsum even if the material has no current market. Gypsum can be dewatered and compacted; if buried separately in a landfill, it could be reclaimed later for commercial use. More recently, the US. Department of Commerce published the report of its Technical Advisory Board on the subject of sulfur oxide control technology. The authors, who represent a wide range of interests, found that flue gas desulfurization was definitely available. However, their studies indicate that the least-cost approach for many utility sites could be a combination of physical coal cleaning and scrubbing. They noted that for some eastern coals the total quantity of solid wastes (coal ash plus scrubber sludge) may be less with this type of operation than it would be if coal were burned as mined-without SO2 scrubbing. We look forward to your continuing coverage of sulfur oxide control technology. Robert 1.Waish, Chief Control Technology Office EPA Research Triangle Park, N.C. 2771 1
Cleaning the water Dear Sir: Your editorial (fS&T, February 1976, p 113) was of considerable interest to me. Many of your statements coincide with statements that I have made as a representative of the water supply industry. It is just inconceivable to establish nationwide uniform rules and regulations when naturally water supplies vary. Obviously, from a legalistic enforcement viewpoint, without concern for costs, this may be expeditious. Presently the National Commission on Water Quality is completing its 2.5 yr study on P.L. 92-500 at a cost of 17 million dollars. I wonder what kind of law would have been promulgated if this information would have been gathered prior to enactment, rather than emotionally first creating and then secondly attempting to solve the problem. C. A. Buescher, Jr., Vice President St. Louis County Water Co. University City, Mo. 63124
