ENVIRONMENTAL IMPLICATIONS 



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I 





PURE CH, 



NATURAL GAS 



LPG 



FUEL OIL 

 ORDINARY GASOLINE 



HIGHLY AROMATIC GASOLINE 

 CRUDE OIL 



RESIDUAL OIL 



BITUMINOUS COAL 



Fig. 1 Hydrogen-to-carbon ratios for various hydrocarbon fuels. 

 (Data from Wiser, 1973.) 



the impurities and potential pollutants present in the feed coal must 

 be removed. The hydrogen-to-carbon ratio can be enriched in several 

 ways, e.g., by removing the volatile hydrogen-rich organic content 

 through pyrolysis, adding extra hydrogen to the carbon contained in 

 the coal, or producing CO and H2 from coal and catalytically 

 reacting the molecules to form methane and/or higher hydrocarbons 

 (Richmond, Reichle, and Gehrs, 1976). In general, the greater the 

 enrichment, the higher are the energy costs. 



Although more than 20 processes for converting coal are being 

 developed (Energy Research and Development Administration, 

 1977), sufficient similarities exist to list only five general types 

 (Fig. 2), including two for gasification and three for hque faction. 

 Coal gasification can produce either low- or high-Btu gas. Low-Btu 

 gasification produces a fuel usable at a stationary source, such as a 

 power-generating facility. Processes for converting coal to low-Btu 



