Pump Storage Hydroelectricity

Pump Storage HydroelectricityDebojyoti MukherjeeEE 3rd year 44

What is Hydroelectric power?

Water is stored at an elevation. Then it is released at a fixed rate, the potential energy stored in the water is used to drive a turbine which works as a prime-mover for the generator.

It is most popular renewable source of energy.

It now supplies 17.5% of worlds electricity needs.

In india it supplies 14.35% i.e 42,783 MW of electricity.

We errect dams in front of natural waterfalls and and direct the flow of water to the turbine. The turbine converts flow energy in water to mechanical energy and turbine acts as a primemover to an electrical generator which converts mechanical energy to electrical energy at a constant voltage and 50hz frequency.Slide from point2....

What is Energy Recapturing?At day time most factories, offices and households are demanding electricity and this is called on-peak period.

since industrial electricity rates are higher than the domestic rates it is also high-profit or high-cost electricity.

Industry should not be hampered due to power shortage thats why electricity during on-peak is high-valued.

Pump Storage SchemeIt is a type of hydroelectric plant but in this case water is not naturally present at the elevation, instead water is pumped using Low-cost off-peak electric power from the grid or onsite steam plant.

It is a storage mechaism used for high power demand at peak hours, the water is released just like an regular hydroelectric plant and the excess power demand is fulfilled.

It is very similler to conventional hydroelectric plant. Only difference is that it does not generate power instead it is used for storing energy. It converts redunted electrical energy to gravitational potential energy of water.Slide....

Pump Storage Scheme cont...

Helps to balance the flow of power across transmission networks by absorbing excess when electricity demand is low and releasing it when demand increases.The diagrams show the flow of electricity and water during various operations.

Number of machines Four unit scheme: separate generator, motor, pump and turbine is used and they operate independently. The cost is generally more. Hence not commonly employed

Three unit scheme: The generator and motor are same devices and in tandem with separate turbine and pump. This sceme is more commonly used.

Two unit scheme: Same device work as both turbine and pump and another device serves as both generator and motor. This method is gaining popularity.

Recirculation type PSSThe water volume in upper and lower reservoirs are same, the same water is used in pumping and generation process.

Seepage and evaporation can be taken care by small inflows in upper or lower reservoir.

Power is generated only during on-peak period.

This scheme is more feasible where potential head is already present.

Mixed PSSA conventional hydroelectric plant and a pure recirculation pump strorage is combinely used in this method.

The upper reservoir is too large and supplies water in most time of the year when sufficient water is available.

During off-peak period it can be used as conventional plant.

In dry seasons plant is used for pump storage scheme only.

Advantages of PSS

Advantages

Converts low-cost,Low-value off-peak energyTo high-value, high-cost, on-peak energyLoad levellingCan strore large amountOfenergyEco-friendlyCan Work as aSynchronuscondenserQuick start-up time(