Reservoir Operations Study Water Quality Evaluation

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TENNESSEE VALLEY AUTHORITY
Overview of Water Quality and Power
Generation Hamilton County Department of
Education In-service Workshop
David L. Bowling, P.E.
River Operations
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Water Quality and Power Generation
Power generation and general information Summer
demand Winter demand Load following and
recovery Conventional hydroelectric
power Raccoon Mountain Water quality Hydro
thermal What is it? Why worry about
it? What we do to manage it Conflicts with
generation Reservoir Releases Improvement How
we improve the water below dams
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Hydro Power
Benefits Hydro is least expensive form of
generation Hydro is one of the cleanest forms
of generation Hydro is TVAs most flexible form
of generation
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Power Demands and Values
Spring and Fall
Winter
Summer
Winter peaks can be several days Availability
of hydro usually not a problem due to high
inflows Winter peaks typically 30,000 megawatts
Spring and fall are generally low power
demand Peak loads average 20,000
megawatts Maintenance performed during this time
Summer peaks typically last all summer for
several hours per day Summer peaksare around
28,000 to 32,000 megawatts Hydro generation must
be rationed
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Hydro Generation
Approximately 11 percent of TVAs generating
capacity 11 coal-fired plants (15,023 MW) 29
hydro plants (3,305 MW) 5 nuclear units (
(5,751 MW) 1 combustion turbine (4,643 MW) 1
pumped-storage plant (1,624 MW) Red Hills (440
MW) U.S. Army Corps of Engineers (405
MW) TAPOCO (326 MW)
Total net dependable Capacity 31,517 MW
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Afternoon Megawatt More Valuable Than Evening
Megawatt
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Winter Season
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Post Analysis Report
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Hydrothermal Issues
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Monitor and Forecast Hydrothermal Compliance
Thermal plant operators, environment
coordinators, check compliance data Run
water-temperature forecast models based
on Forecast and measured meteorology Upstrea
m water temperature Forecast and measured hydro
releases Plant information Number of cooling
towers, lift pumps, gates Currently
running Available for use Condenser and
other plant performance data If the input is
wrong, the forecast is wrong
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When Water Temperature Exceeds Limit, Plants
Reduce Output
When predicted forecast exceeds the limit Use
cooling towers Reduce generation Curtail
generation during nonpeak hours When
temperature exceeds safety limit Shutdown plant
immediately Anything that improves plant
efficiency, such as condensers Reduce
discharge temperature Reduce derates
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Low Flow, Warm Discharge Water Recirculates Back
to Intake
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Depleted Dissolved Oxygen
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Aerating Turbine
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Aerating Weirs
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Weirs, Surface-Water Pumps, and Line Diffusers
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Layout of Line Diffusers
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Maintaining Minimum Flow Small Hydro Units
Requires separate aeration system No beneficial
at all projects
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Benefits of Increased Dissolved OxygenTims Ford