The document discusses pumped-storage hydroelectricity (PSH) as a method for energy storage and load balancing in electric power systems, utilizing gravitational potential energy of water. It explains how water is pumped between reservoirs to generate electricity during high demand and store energy during low demand. The advantages of PSH include its ability to store large amounts of energy and operate independently of river flow, unlike traditional hydroelectric plants.

1. ENERGY RESOURCES
PUMPED STORAGE HYDRO-ELECTRIC SYSTEMS

2. 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

3. 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.

4. 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 energy
Basically, gravitational potential energy of the falling water is
converted to kinetic energy which is also converted to electric
energy.
Ep ---------→ Ek ----------- → Eelectric

6. Economic Impact of P-S-H
The 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.

7. 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 ∆ 𝒉, the gravitational potential
energy available is = mg ∆ 𝒉 Where:
o m is mass
o 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 ∆ 𝒉) t = (v𝝆g ∆ 𝒉)/ 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 𝝆 is the density of the water.

8. 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.

9. SOLUTION
In one second the gravitational potential energy lost
by the system is mg ∆ 𝒉 = 600 × g × 260 = 1.5 MJ
 The efficiency is 65%
∴ Output power = 1.5 × 106 × 0.65 = 0.99 MW
Got it ?

10. 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

11. 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!!!

12. HOPE YOU LEARNT SOMETHING ABOUT
THIS SOURCE OF ENERGY..............

13. To be continued…!!
This Power point was made by Benjamin Kubwimana
E-mail: kbenjah97@gmail.com