Water Usage in US Water Usage in US

Water Usage in US

Water Usage in US (2)

Types of Available Water Fresh Groundwater Saline Groundwater Fresh Surface Water Saline Surface Water

% of Water Types Used for All Sectors groundwater surface water Fresh Water Saline Water

Water Usage by User in US other (ground, fresh) other (ground, saline) other (surface, fresh) other (surface, saline) Public (ground, fresh) Public (surface, fresh) Irrigation (ground, fresh) Irrigation (surface, fresh) Thermoelectric (ground, fresh) Thermoelectric (surface, saline)

Water Uses in Energy Production • Cooling water for steam turbine condenser (largest user) • Makeup water treatment plant (second largest user; remaining in no particular order) • Boiler makeup water • NOx control for gas turbines • Auxiliary plant cooling water • Makeup water to flue gas desulphurization • Ash handling and disposal • General domestic use

Water Used for Cooling Purposes Open Loop System • H 20 withdrawn directly from source • Lake/river • Heated H 20 returned to source • Thermal pollution • Entrainment problems • Generally only used at coastal facilities Closed Loop System • Uses tower to transfer heat to ambient air • Withdrawal <5% of open systems • Overall greater consumption

Types of Cooling Systems • • Once through with cooling ponds/canals Freshwater once through Saline once through Recirculating systems with cooling ponds/canals Recirculating systems with forced draft cooling towers Recirculating systems with induced draft cooling towers Recirculating systems with natural draft cooling towers (Yang)

Types of Water Used by Thermoelectric Plants Current Sources • • • Fresh Groundwater Surface Freshwater Surface Saline water Public Delivery Sewage Mixed water sources (Water Use, Yang)

Cooling Water Sources industrial wastewater sewage reservoir waste water effluent wells rivers cooling pond ground water treatment system Ocean municipal aquifer mill supply lakes

Treatment of Water • Impurities present in surface/groundwater sources that must be addressed • Total dissolved solids – For many processes, it is unnecessary to reduce except in substantial evaporation losses • Suspended solids/particulate matter – Treatment depends on level of solids present – Can cause silting/fouling problems in cooling towers/circuits • Colloidal species – Can’t be removed by ion exchange technology – Must use membrane separation technology • Dissolved organic matter – Can cause corrosion in turbine cylinders if not treated Water Treatment for Fossil Fuel Power Generation, Paton

• Research for new sources … • Mine pool water • geological carbon sequestration & coal bed methane produced water • Industrial/municipal wastewater • . . . and research for water reuse & recovery • reuse power plant cooling water • recover water from plant flue gas NETL

New Sources

Water Usage in Hydroelectric Power • Consumptive Uses • Increased sfc. area of reservoir causes faster evaporation • Non-consumptive Uses • Water flowing through turbine • Evaporation = 18 gal/k. Wh consumed by end user (NREL “Consumptive Water Use for US Power Production”)