WSP11937

• File Number: 8040.200
• Description: Section D General Studies-Energy
• Date: 1/1/1974
• Author: Davis-Wood-USGS
• Title: Energy-Oil Shale-Geological Survey Circular 703-Water Demands for Expanding Energy Development
• Water Supply Pro - Doc Type: Publication

commercial.scale operations exist in the United States
and none of several possible processes has been shown to
be competitive with alternate fuels. Among processes
under consideration are (be following: Consol, solvent
refining, H-Coal, and COED (Hottel and Howard, 1971,
p. 161-182). Unit water-consumption estimates range
from as little as 0.2 acre-ft (247 m') annually per bpd of
synthetic-oil output to as much as 1.3 acre-ft (1,600 m')
per year per bpd capacity. The National Petroleum
Council (1973) adopted a unit consumptive-use value of
0.2 acre-ft (247 m') per year per bpd capacity. Until
better data become available, this figure is probably as
good an estimate as any other for planning purposes.
The 0.2 acre-ft (247 m') per year per bpd capacity
translates into 20,000 acre-ft (25 million m3) per year
for 100,000 barrels (16,000 m3) per day of oil.

SUMMARY

Consumptive demand for water in various energy
processes is summarized in table 3 and figure 4. Here
consumption of water is compared on the basis of
energy output in millions of Btu. The larger consumptive

uses are associated with large cooling requirements,
particularly in thennal-electric power generation, where
under the best present design nearly two-thirds of the
energy input is dissipated as waste heat, mostly through
evaporation of water. It should be noted that figure 4
includes both refining and conversion processes; hence,
at least some of the fuel produced in oil refining
becomes energy input in fossil-fueled electric generation,
and the uranium fuel processed becomes energy input in
nuc1ear-electric generation. To this extent these water
requirements are additive in the total fuel cycle; how-
ever, much of the fossil-fuel product goes to other
energy uses such as transportation, space heating, and
industrial uses, and is not additive. Conversely, much of
the electric power is not used to produce heat (measured
in Btu's) but is used to make light or, in electric motors,
to perform work. The work output of electric motors
relative to input of electric current generally exceeds
80 percent compared to the efficiencies of engines using
fossil fuels which are generally less than 30 percent. The
comparatively large consumption of energy and water in
generating electricity is largely compensated for if the
electricity is used to produce torque.

Table 3.- Waler consumption in refining processes

Process and product

ReI11a1b

Consumptive use
(gallons per
10' Olu)

Ulanium . . . . . . . . . . . . . . . .

14.34

Oil ..................._
Pipeline gas nom coat. . . . . .

6.7

a. Water cooling (90
pelcent load Factor).

72-158

b. Partial air cooling (90
percent load Factor).
Synlhetic oil From coal. . . . .

37 -79

31-200

Oil from shale . . . . . . . . . . . .

19-29

Reactor fuel for 1,000 mw nuclear plant annualized
For 80 percent load Factor. Includes water
consumed at power plants supplying electricity
For processing.
Aver.lge For U.S. refineries (Otts, 1963).
Lurgi gasification foUowed by melhanation stage.
Product about 1,000 Btu per standard cubic fool.
Con5Umption varies with amount of blowdown
required; directly proportional to mineral
content and turbidity of cooling supply.
Assumes 85 percent of cooling demand met by
nonevaporativc air cooling.
General estimate based on several potenlial
processes using pressure hydrogenation
technology.
Includes water requirement For spent shale disposal.

A lIerage waler consumption in electrical generation
I Most efficient design assumed; at 80 percent load Factor)

Process

Water consumption,
(gaUons per kwhr)

Water consumption (gaUons
per 10' Otu of electrical
output)

Fossil-fueled ...........................
Nuclear. . . .. . . .. . . . . .. .. . . . ... . . .. . . . .
C..eothelmal .. . . . . . . . . . . . . . . . . . . . . . . . . . .

0.5
.8
1.8

146
234
527

"

12