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76 Membranesfor Industrial Wastewater Recovery and Re-use

3.1 The ower industry: water requirements for power generation
and coo P ing water

3.1.1 Water demand by the power industry
In industrialized nations significant quantities of water are needed for power
generation and cooling applications, greatly exceeding the quantities of water
used for all other purposes (Fig. 3.1). For example, in the USA thermoelectric
power generation accounts for about 47% of the 5.5 x 1011 m3 of water that is
consumed annually (Solley et a]., 1998). A major water use is for condenser and
reactor cooling in steam-electric power plants. For power plants equipped with
wet towers for steam condensation, the evaporation of water in the cooling
tower can account for up to two-thirds of the total plant water use. Other
applications for cooling water include air conditioning systems, food and
beverage manufacture, meat and dairy industries, chemical manufacturers,
and petroleum refineries (Asano and Levine, 1998).
On a global basis, it has been estimated that about 10 000 GW of new electrical
generating capacity will be required by 2050 (Powicki, 2002). Fresh water is an
essential resource for the production of electricity, as it is needed for high-purity
steam, condensate cooling, and miscellaneous operations including dust
suppression. While the net water requirements depend on the distribution of
energy sources (nuclear, fossil fuel, waste-to-energy, hydropower, solar, wind,
etc.), it is obvious that energy production is dependent on water availability. In
addition to projected increases in energy and associated water requirements,
liquid discharges from industrial water users are subjected to increasingly
stringent requirements in many locations. In the future, it is likely that many
thermoelectric power generation facilities will be required to comply with so-
called zero liquid discharge (ZLD) requirements to meet long-term watershed

Fresh water 0 Ground water W Saline
Figure 3.1 Water use in the USA (data from Solley et al., 1998)