Water Usage in US
Water Usage in US (2)
Types of Available Water
% of Water Types Used for All Sectors
Water Usage by User in US
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Open Loop System Closed Loop System•H20 withdrawn directly from source
•Lake/river•Heated H20 returned to source
•Thermal pollution•Entrainment problems
•Generally only used at coastal facilities
•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
rivers
lakesmunicipal
wells
treatment system
cooling pond
sewage reservoir
waste water effluent
Ocean
aquifer mill supply
groundwater
industrial wastewater
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 = 18gal/kWh consumed by end user
(NREL “Consumptive Water Use for US Power Production”)