"Pumped Storage" is another form of hydro-electric power. Pumped storage facilities use excess electrical system capacity, generally available at night, to pump water from one reservoir to another reservoir at a higher elevation. During periods of peak electrical demand, water from the higher reservoir is released through turbines to the lower reservoir, and electricity is produced . Although pumped storage sites are not net producers of electricity - it actually takes more electricity to pump the water up than is recovered when it is released - they are a valuable addition to electricity supply systems. Their value is in their ability to store electricity for use at a later time when peak demands are occurring. Storage is even more valuable if intermittent sources of electricity such as solar or wind are hooked into a system.
Pumped storage plant is a unique design of peak load plant in which the plant pumps back all or portion of its water supply during lo load period.The usual construction is a lowand high elevation reservoirs connected through a penstock.The generating pumping plant is at the lower end.The plant utilises some of the surplus energy generated by the base load plant to pump water from low elevation to highelevation reservoir during off peak hours.During peak load period this water is used to generate power by allowing it to flow from high elevation reservoir through reversible hydraulic turbine of this plan to low elevation reservoir.Thus same water is used again and again and extra water is required only to take care of evaporation and seepage.
The main important point in this plant is reversible turbine/generator assemblies act as pump and turbine (usually a Francis turbine design).During low load periods it acts as pump and pumps water from low to high elevation reservoir.During peak load periods it acts as turbine when water flows from high to low elevation reservoir.
Advantages
- Without some means of storing energy for quick release, we'd be in trouble.
- Little effect on the landscape.
- No pollution or waste
- Expensive to build.
- Once it's used, you can't use it again until you've pumped the water back up. Good planning can get around this problem
