Other Industrial Users of Water
On this map, industrial
water consumption is considered to be the water use known as
"manufacturing" in the set of principal water use categories
for Canada. This use class accounts for about one-sixth (16%) of
water used.
Figure 1 shows the principal water user classes of Canada. Industry
is covered by three of these: in addition to manufacturing, thermal
power generation is an industrial use, and a small part (17%) of
municipal water use is also used by industry. This usage is not
classed with manufacturing as it consists of water supplied directly
by municipal water systems to small industrial concerns.
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Figure 1. Principal Water Uses in Canada, 2000
Thermal power generating, which includes both conventional and
nuclear power generating plants, withdrew slightly more than 63%
of the total water intake in 1991. Next to fuels, water is the most
important resource used in thermal power production. Production
of one kilowatt-hour of electricity requires 140 litres of water
for fossil fuel plants and 205 litres for nuclear power plants.
A small amount of the water is converted to the steam which drives
the generator producing the electricity. Most of the water, however,
is used for condenser cooling.
Why is so much cooling necessary? Because generation processes
can only convert 40% of the fuel's energy into usable electricity.
The rest is waste heat. Water is used in large quantities to remove
waste heat by cooling down the condensers. This requires a continuous
flow of cooling water circulating through the condenser. All the
cooling water is therefore returned to the environment much warmer.
However, the temperature can also be reduced using cooling towers
and other such devices.
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