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Juan River plus 765 gpm (2.89 m3 per minute) ofmois. ture in the coal input, and 630 gpm (2.38 m3 per minute) produced by the methane-synthesis reaction. Of this total input, some 2,200 gpm (8.3 m3 per minute) will react to form gas, 1,300 gpm (4.9 m3 per minute) will be piped to the coal nnne and other offsite users, 900 gpm (3.4 m3 per minute) will evaporat'e from waste , ponds, 190 gpm (0.72 m3 per minute) will leave as wet ash, 2,965 gpm (I \.2 m3 per minute) will escape in the cooling system, and the remaining 840 gpm (3_2 m3 per minute) is accounted for in numerous small plant dis- charges. This represents an extreme case of water conser- vation as the plant is engineered so that only 15 percent of gross cooling requirements is met by evaporative cool. ing. In other areas and under other conditions water consumption might be considerably higher. In terms of annual consumption at an assumed load factor of 91 percent, the above estimates indicate total water consumption of 14,000 acre-ft (17 miltion m3) per year of which about 2,500 (3 million m3) is supplied to the mine and other offsite uses, leaving a consumptive demand for the plant of about \I ,500 acre-n (14 million m3) per year_ Of the lolal consumption of t4,000 acre-n (17 million m3) per year, tl,700 acre-n (14 million m3) per year is supplied by imported waler, 1,300 acre-n (\.6 million m3) per year is moisture con- tained in the input coal, and the remaining 1,000 acre-n (\.2 million m3) per year is produced in the methane- synthesis reaction. The Synthetic Gas-Coal Task Force (1973, p. XIl-3) calculated substantiaUy higher make-up water demand, for typical coal-gasification plants. The following table summarizes their estimates of the annual water require. ments of a typical 250 billion Btu per day (~250 million scf per day or 7 million m3 per day) plant as follows: It was assumed in the first instance that the above plants would be totaUy water cooled; the different cates of make-up reflect different requirements for blowdown which depends upon the quality of input water. The 3-percent rate would apply to high-quality supply water while the 7-percent rate would apply to brackish or highly turbid supplies. The lower line of the table esti- mates water demand for in-plant use based on partial air cooling~ the lower ranges of these estimates are compara- ble to the design estimates for the Burnham Complex. To summarize, water consumption in coal gasification plants producing pipeline gas of 250 million scf per day (7 million m3 per day) capacity can be expected to range from about 10,000 acre-ft (\2 million m3) per year where water is at a premium to 45,000 acre-ft (55 million m3) per year where abundant but poor- quality warer is used for cooling. The principal differ. ences are in evaporative cooling requirement and relate to the extent to which air cooling is employed and greater waste-water disposal where input water is of low quality. Production of low Btu gas for power.plant consump- tion onsite ralher than high Btu pipeline-quality gas is considered feasible in many situations. This can be accomplished in essentially the way planned at the Burnham Complex except that the methane-synthesis process is omitted. As the methane synthesis does not playa major role in water consumption, it is believed that this alternative mode of gas production would have tittle bearing on consumptive demand for comparable Btu outputs. COAL L1QUEFACfION Estimation of unit values of water consumption in producing oil from coal is tenuous at best because no Make-up role, in percen/oge of cooling K10ler circum/ion 3 Bituminous and subbitunllnoUS 7 5 1,742 396 20,178 22,316 32,451 16,225 \I Lignite 3 5 7 1,705 1,705 1,705 359 359 359 10,096 16,828 23,559 12,160 18,892 25,623 17,682 27,472 37,259 8,845 13,682 16,630 045:1 Process water, gpm . . . .. . . . . . . . . . . . . .. . .. . . Boiler make-up, gpm ...................... Cooling make-up, gpm ..................... 1,742 396 12,107 1,742 396 28,249 Total, gpm ....................... .. . . . .. 14,245 30,387 Total, acre-ft per year at 90 percent load factor.. 20,714 Minimal demand assuming partial air cooling, acre-ft per year at 90 percent load factor . . . . . 10,358 22,094 44,187