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<br />I
<br />
<br />Program envisions mining more than 50,000 tons
<br />(45,359 metric tons) a day from an underground
<br />mine and more ilian 100,000 tons (90,718 metric
<br />tons) a day from an open pit mine.
<br />The od shale must be heated to about 9000 F
<br />(4820C) to convert the solid organic material in the od
<br />shale to gas and oil vapors. The three most advanced
<br />ret'orts developed for heating oU shale are the Union Oil
<br />Retort, the Gas-Combustion Retort, and the TaSCa
<br />Retort'. The first two maintain controlled combustion of
<br />shale within the retorts, but the TaSCa process uses
<br />heated ceramic balls with fmely crushed shale in a
<br />rotating cylindrical drum. The shale oil produced by aU
<br />these retorts is a low-gravity, moderate-sulfur, high-
<br />nitrogen oil that has a high pour point and is rather
<br />viscous. The shale oil probably will be upgraded by
<br />hydrocracking, or some other process, to reduce its vis-
<br />cosity and make it suitable for pipeline transport to a
<br />refinery located where more abundant water supplies are
<br />avaUable.
<br />The largest use of water in the production of shale oU
<br />is for disposal of the dry spent shale after it has been
<br />crushed and roast'ed to extract the hydrocarbons. The
<br />water is used for dust control while the spent shale is
<br />being transported (possibly as a slurry), but it's most
<br />important use is in compacting and stabilizing the dis-
<br />posal pile. Spent shale that contains 20-30 percent
<br />water will set up like a weak portland cement'. In fact, if
<br />the slope of t'he face of the pile is 180 or less, the limit-
<br />ing parameter on the height to which a box canyon can
<br />be ftIled is the load-bearing strength of the alluvial floor
<br />of the canyon. (U.S. Department of the Interior, 1973,
<br />v. t, p. 142-143.)
<br />Estimates of the most likely amounts of water con-
<br />sumed by an oil-shale mine, retort, and upgrading plant
<br />of 100,000 barrels (]5,899 m') per day capacity of
<br />shale oU range from about 7,500 gpm (gallons per
<br />minute) (28m' per minute or 12,]50 acre-ft per year)
<br />to about 11,400 gpm (43 m' per minute or ]8,420 acre-
<br />ft per year). Associated urban uses would increase the
<br />estimated range to 8,350-12,400 gpm (31.6-46.9 m'
<br />per minute or 13,400-20,100 acre-ft per year). The
<br />average of the high and low estimates for each use is (in
<br />gallons per minute):
<br />
<br />Processed shale disposal
<br />Shale oil upgrading . . . . . . . . _
<br />Power requirements ........
<br />Retorting _...............
<br />Mining and crushing ........
<br />Revegetation. . . . . . . . . . . . . .
<br />Sanitary use ..............
<br />Associated urban. . . . _ . . . . _ .
<br />
<br />4,500
<br />2,300
<br />1,]00
<br />800
<br />550
<br />220
<br />30
<br />900
<br />
<br />Total . . . . . . . . . . . . . . . . 10,400
<br />
<br />A series of mines and plants will probably be required
<br />to produce 1 million barrels (158,899 m') per day of
<br />shale oU. The Final Environmental Statement for the
<br />Prot'otype au Shale Leasing Program assumed a mix of
<br />17 mines and plants including II underground, 2 open
<br />pit, and 4 in situ mines would be needed for 1 million
<br />bpd (barrels per day)_ Based on the assumed technol-
<br />ogy mix, the Final Environmental Statement estimated
<br />that 121,000-189,000 acre-ft (149 million-233 mil-
<br />lion m'J) per year of water would be consumed in
<br />producing I million barrels (158,89910') per day of
<br />shale oil (t'able I).
<br />The source of water for oil-shale developments must
<br />be the Upper Colorado River Basin, although the initial
<br />mines on the Prototype Leases in the Piceance Basin in
<br />Colorado may develop enough ground water to satisfy
<br />all their water needs. A long-term, large-scale oil-shale
<br />industry in Colorado, Utah, and Wyoming will depend
<br />on diversion of stored surface water from the Colorado
<br />River Basin. Table 2 shows the status of water use in the
<br />Upper Basin. Water is available for. an industry of more
<br />than I million bpd of shale oil if water not committed to
<br />other uses is made available to oil-shale developments. A
<br />much larger industry (several million barrels per day)
<br />would require purchase and transfer of water rights from
<br />agriculture to industry.
<br />
<br />COAL GASIFICATION
<br />
<br />As there are no modern-design coal-gasification plants
<br />of commercial scale in the United States, estimates of
<br />water demand must be based on research operations.
<br />foreign experience, and design data of projected plants.
<br />One of the chief sources of information is an engineering
<br />report of the EI Paso Natural Gas Co_ Burnham I Coal
<br />Gasification Complex planned for a site near
<br />Farmington, N_ Mex. (Stearns-Roger Inc., 1973). The
<br />processes being considered for that complex, designed
<br />to produce 288 million scf (standard cubic feet) per
<br />day (8.15 million m' per day) of pipeline.quality gas
<br />(954 Btu per ft' or 9.87 kwhr per 10'), include coal
<br />gasification by the Lurgi process followed by shift con.
<br />version, gas cooling, gas purification, and methane syn-
<br />thesis. In simple terms, the Lurgi process produces a low
<br />Btu product (about 400 Btu per fl' or 4.14 kwhrper 10')
<br />which is upgraded by methane synthesis to pipeline qual-
<br />ity. In various stages water is consumed in the chemical
<br />reaction; cooling requirements contribute additionally to
<br />the overaU water demand. Because water is scarce in the
<br />region of the plant, recycling will be used to the
<br />maximum. and air cooling will be used insofar as
<br />practicable. The water input will consist of about
<br />7,000 gpm (26 m' per minute) diverted from the San
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<br />0456
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