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ENERGY RESOURCES
PUMPED STORAGE HYDRO-ELECTRIC SYSTEMS
There a number of ways in which water can be used as a primary energy resource.
These include: Pumped storage plants Hydroelectric plants Tidal barrage Tidal flow systems And wave energy
What’s that up there???
Pumped-storage hydroelectricity (PSH) is a type of hydroelectric energy storage used by electric power systems for load balancing.The method stores energy in the form of gravitational potential energy of water, pumped from a lower elevation reservoir to a higher elevation.
Process in energy production
The gravitational potential energy of water held at a level above a reservoir is converted to electric energy as water is allowed to fall to the lower level.How is electrical energy obtained gravitational potential energy?The kinetic energy of moving water rotates turbine faster which then generates electricity - electric energyBasically, gravitational potential energy of the falling water is converted to kinetic energy which is also converted to electric energy. Ep --------- Ek ----------- Eelectric
Economic Impact of P-S-HThe demand that consumers make for energy is variable and can not always be predicted. From time to time the demand exceeds the output of the baseload stations. Pumped storage is one way to make up for this deficit.A pump storage system involves the use of two water reservoirs-some times a natural feature such as a lake, sometimes a man-made lake or an excavated cavern inside the mountain.
These reservoirs are connected by pipes. When demand for energy is high, water is allowed to run through the pipes from the upper reservoir to the lower via water turbines. When demand is low and electrical energy is cheap, the turbines operate in reverse to pump the water back from the lower to the upper reservoir.
HOW EFFICIENT IS THE ENERGY PRODUCTION??
Some pumped storage systems can go from zero to full output in tens of seconds. The larger systems take longer to come up to full output. However, substantial outputs are usually achieved in only a few minutes from switch on.For a pumped storage system that operates through a height difference of the gravitational potential energy available is = mg Where:
o m is masso g is the gravitational field strength
So the maximum power P available from the water is equal to the rate at which energy is converted in the machine and is:
P = (mg ) t = (vg )/ t where t is the time for mass m to move through the generator, is the volume of water moving through the generator in time t and is the density of the water.
An example of typical exam question.
Water from a pumped storage system falls through a vertical distance of 260 m to a turbine at a rate of 600 kg/s. The density of water is 1000 kg/ m3. The overall efficiency of the system is 65%
Calculate the power output of the system.
SOLUTION
In one second the gravitational potential energy lost
by the system is mg = 600 × g × 260 = 1.5 MJ
The efficiency is 65%
Output power = 1.5 × 106 × 0.65 = 0.99 MW
Got it ?
IMPORTANCE OF PUMPED STORAGE HYDRO-ELECTRIC SYSTEMS IT CAN STORE LARGE AMOUNTS OF ENERGY
IT CAN MANAGE POWER SUPPLY – QUICKLY “TURNED ON
PUMPED STORAGE PLANTS ARE UNIQUE AMONG ALL THE HYDROELECTRIC POWER PLANTS AS NO FLOWING WATER SUPPLY IS REQUIRED. ONCE THE HEAD OR TRAIL POND IS FILLED, THEN ONLY INFLOW REQUIRED IS TO COMPENSATE FOR THE EVAPORATION AND SEPARATE LOSSES
PUMPED STORAGE PLANT CAPACITY IS NOT LIMITED BY THE RIVER FLOW AND SEASONAL VARIATIONS IN THE FLOW. THIS IS THE ADVANTAGE OF PUMPED STORAGE PLANTS WHICH CAN BE OPERATED ALL OVER THE YEAR IN ALL SEASONS
Pump storage: I’m so efficient than you!
Wind power: you’ve also got disadvantages...
YOU’RE VERY DEPENDENT ON LOCATION
YOU’RE SO AFFECTED BY DRASTIC CHANGES TO ENVIRONMENT (FLOODING)
YOUR INITIAL COSTS VERY HIGH
YOU’RE ALWAYS MOVING UP AND DOWN!!
HAVE NO AIR CONDITIONER!!!
HOPE YOU LEARNT SOMETHING ABOUT THIS SOURCE OF ENERGY..............
