The Pumped Storage Hydro Power Plant is a clean technology an the green house gas and other pollutant emission can very negligible in this generation method.
However initial construction of Pumped Storage Hydro Power plant will have an impact of existing environment. In carrying the peak-loads of a system, pumped storage hydro-electric plants decrease the operation costs of the steam plants working in combination with them, Off peak energy form steam or diesel plants is used to drive the pumps.
Pump storage peak-load plants have an advantage over the usual reservoir peak-load plants. Following are some of the major featurs of Pumped Storage Hydro Power Plant
Component of Pumped Storage Hydro Power Plant
A pump-storage plant is useful in the system to supply sudden peak-loads of brief duration. Old and inefficient steam station are used for this purpose where peak-load hydro-plants or pumps
Pump storage power plants consists two reservoir
Like a conventional hydropower plant, a dam creates a reservoir. The water in this reservoir flows through the hydropower plant to create electricity.
Water exiting the hydropower plant flows into a lower reservoir rather than re-entering the river and flowing downstream.
Using a reversible turbine, the plant can pump water back to the upper reservoir. This is done in off-peak hours. Essentially, the second reservoir refills the upper reservoir. By pumping water back to the upper reservoir, the plant has more water to generate electricity during periods of peak consumption.
The dam for the project is planned to be of concrete gravity type to create regulating pond for hydropower generation. Hence, the dam should be designed in consideration of safety and stability. The design requirements for the dam are given topographical, geological and structural conditions, and economical efficiency.
General requirements of the dam design include the following;
- To be stable and safe against earthquakes, floods, etc.
- To have sufficient free board against waves caused by winds
- To construct concrete with durability for its long time life
- To install measuring installments to observe its behaviors during construction and O&M stage.
The spillway and dissipation structures will radial gates on ogee crest spillway with a cute and flip bucket.
The surge tank will be designed to allow for transient conditions under reservoir operating water levels between MOL and FSL. The surge tank characteristics will be determined in a way to ensure:
- Stability of the operation of the power plant under small load steps,
- Load acceptance by the units within required time period.
- Closure of the penstock discharge after load rejection in the required time without excessive surge wave overpressure in the penstock.
Gates on the dam open and gravity pulls the water through the penstock, a pipeline that leads to the turbine. Water builds up pressure as it flows through this pipe. The function of an intake structure at a hydroelectric project is to direct water to the water passages to the powerhouse under controlled conditions. An intake contains transhracks that prevent large debris from entering the water passages and gates to control the flow of water. The design requirements for intakes are based of geologic, hydraulic, structural and economic considerations.
The general requirements for the intake include the following.
- Intake structure must be stable, even when dewatered;
- The velocity through the trashracks, gates and other passages must be confined within practical limits;
- The water passages must be shaped so that the transformation of static head to conduit velocity is gradual, with minimum eddy losses;
- The intake must be designed to inhibit the formation of vortices at the intake; and
- All apparatus should be reliable, simple to operate and easy to maintain.
As the turbine blades turn, so do a series of magnets inside the generator. Giant magnets rotate past copper coils, producing alternating current (AC) by moving electrons.
Out of every power plant come four wires: the three phases of power being produced simultaneously plus a neutral or ground common to all three.
The transformer inside the powerhouse takes the AC and converts it to higher-voltage current.
Types of Pumped Storage Hydro Plants
Pure pumped storage
Consists of two off stream reservoirs where electric power generation is primarily dependent on the pumping operation rather than on natural in flow into the upper reservoir.
Pumped-back pumped storage
Generally comprises two reservoirs on the same river so that electric generation relies on both natural inflow and the water that is pumped back.
Seasonal pumped storage
It is an operation that balances the variability of natural fluctuation of river flow, which is generally seasonal, with demand, which may be more uniform and may possibly vary in a direction opposite to supply.
Benefits of Pumped Storage Hydro Power Plant
- Pump Storage Method can be used as energy storage method.
- Pump Storage can use as a solution for peak demand problem.
- Increasing of the quality and reliability of the power system.
- To replace the thermal private power generation system with renewable energy.
- Increasing the availability of water and performance of the pump storage hydro power system in dry seasons.
- This will also useful to maximize the power distribution for peak hour demand.
Limitation of Pumped Storage Hydro Power Plan
- Pumped-storage cannot be operable without receiving the pumping energy. This pumping energy must be cheap.
- The cycle efficiency from receipt of the pumping energy to generation is merely 70% due to the losses at pump-turbine and other equipment/facilities.
- The construction site is limited where the site conditions can meet the pumped-storage requirements including geographical, geological, transmission requirements.
- The dam construction may cause environmental problems, or introduce the activist’s protest.