The Richard B. Russell Dam spans the Savannah River dividing line separating Georgia from South Carolina and serves as a key energy plant.
A creation of the U.S. Army Corps of Engineers, the dam’s construction combines earth and concrete and has an expansive pumped-storage powerhouse.
During non-peak hours, four specially designed reverse-action pump-turbines pump water up to 140 feet high into Russell Lake.
By allowing this stored water back down through the powerhouse during peak hours, electricity is rapidly produced.
Expanding Savannah River hydroelectric generation capacity
The federal plans within the upper region of Savannah River created a water management system of multiple reservoirs.
Building the Richard B. Russell project helped to fill up an important spatial gap that existed between the upper Hartwell Dam and lower Strom Thurmond Lake.
The construction of the initial power house included four conventional generating units that could generate 300 megawatts of power.
In response to increased power requirements in the region, the federal government decided to include another four pumped storage reversible units in the dam powerhouse.
The inclusion of this pumped storage equipment resulted in doubling of the generating capacity of the plant to 600 megawatts.
Reversing reversible turbines to store off-peak electricity
Traditional hydroelectric generating plants depend solely on gravitational water flow downstream to rotate turbine blades.
In reversible pumped storage plants, facility managers can use excess grid power as mechanical potential energy.
At night when demand is relatively low, there is an oversupply of power in the region compared to grid requirements.
This excess power from the interconnected regional transmission system is used to drive four massive electric motors.
These electric motors operate in reverse, thus rotating turbine blades backward and acting as water pumps.
The reversed machines pump the tailwater from downstream Strom Thurmond Lake uphill into the elevated main reservoir.
The refilled main reservoir ensures a supply of millions of gallons of water during heavy afternoon power consumption.
Delivering flexible electricity during peak regional demand
The consumption of electricity shoots up sharply during the afternoon.
Use of pumped storage systems makes it possible for the utility to immediately address any shortage of energy supply.
Thermal plants need several hours before production capacity can be increased, but hydroelectric plants can do so within minutes.
Opening penstock intake gates makes the water held in the lake pass through the plant in a matter of minutes.
The moving water powers both normal and reversible turbine systems that produce up to 600 MW of electricity.
The prompt production helps to maintain the voltage level in the region during bad weather.
Mitigating oxygen depletion in downstream tailwaters
Thermal stratification of the deep reservoir leads to low levels of dissolved oxygen in the bottom layers of water during the summer season.
The discharging of oxygen-depleted water through the hydro turbines can affect the fish downstream in the rivers.
The Corps engineers have provided a commercial oxygenation system within Russell Lake for maintaining water quality.
The direct injection of gaseous oxygen into the deep reservoir layers of water increases the dissolved oxygen content before entering into the turbines.
The process of oxygenation ensures that water entering into the Strom Thurmond Lake satisfies the stringent environmental requirements of the state, according to the U.S. Army Corps of Engineers.
Outlining physical limits of river pumped storage
There are major benefits of operating the dual-reservoir pumped storage system, but physical limitations of operation exist.
The maximum pumping capability depends on the presence of particular levels of elevation of water in the Strom Thurmond Lake downstream.
Drought conditions lead to the drop of tailwater elevations.
Using heavy electrical pumping motors at night involves purchasing cheap electricity outside of the region by external regional utilities.
Gradual sedimentation over time results in reducing the volume of available energy storage near the penstock intake facilities.
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