Energy Storage: Pumped Hydro-Power and Flywheel Energy Storage

Energy Storage 1
ENERGY STORAGE
By Name
Course
Instructor
Institution
Location
Date
Contents

Energy Storage 2
PUMPED HYDRO-POWER ENERGY.......................................................................................................2
PRINCIPLE OPERATION OF THE PUMPED HYDRO....................................................................................2
MECHANICAL DESIGN FEATURE MATERIALS AND CONSTRUCTION......................................................6
1. Forebay and intake structure...........................................................................................................6
2. Head Race........................................................................................................................................7
3. Surge Tank.......................................................................................................................................7
4. Turbines...........................................................................................................................................8
5. Tail Race( Draft Tube ).....................................................................................................................8
Construction of the pumped hydro energy...........................................................................................9
Application and where currently operational.....................................................................................10
Design....................................................................................................................................................10
Summary.............................................................................................................................................12
FLYWHEEL ENERGY STORAGE.............................................................................................................13
OPERATION............................................................................................................................................13
MATERIALS USED IN DESIGN.................................................................................................................15

Energy Storage 3
CONSTRUCTION OF FLYWHEEL..............................................................................................................15
WHERE THIS IS EMPLOYED....................................................................................................................16
DESIGN..................................................................................................................................................16
REAL VIEW OF FLYWHEEL......................................................................................................................19
SUMMARY.............................................................................................................................................19

Energy Storage 4
Question 1
PUMPED HYDRO-POWER ENERGY
PRINCIPLE OPERATION OF THE PUMPED HYDRO
The water moving via the turbine is stored in a `` tail race pond`` for the period of low load. The
water is then pumped back to the head reservoir by the aid of the extra energy present. The water
pumped back can then be employed again in the production of electrical energy during the periods of
peak load (McMurry, 2015).
Real view of pumped hydroelectric power plant
Fig: Showing a pumped hydroelectric power plant (Richard, W., 2013)

Energy Storage 5
Fig: showing a real view for pumped hydro power energy
The assembly of the pumped hydro system can be illustrated as in the diagram below;
Fig 1: Showing the assembly of the pumped hydro technology. (Webinars, 2012).
The pumped hydro technology is used at the places where the amount of water present is inadequate
therefore water flowing to the turbines is first stored in the reservoir (Webinars, 2012). During
the ``charge`` period electric motor will drive the pump having more water from a lower to the
upper reservoir, there are some losses which are associated with this which makes this
technology to have an efficiency of about 82%. The diagram below summarises the process
(Bany, 2012).

Energy Storage 6
Fig 2: showing the working principle of the pumped hydro. (pakistan, 2013, p. 123).
The storage capacity of this technology is shown by the following equation;
Q=V× H × ρ × η × g ...............................................................................................................................(1)
Where Q is the storage capacity, V is the volume of the reservoir, H is the upper reservoir elevation,
η is the efficiency.
The amount of storage in the pumped hydro technology is much higher than what is stored in the
battery technology (Bhatt, 2012, p. 177). The amount of power per day (kWh/ day) needed to pump
a specific amount of water per day can be given by the following equations;
Pelec= 0.1885 × H ×Q
η
...............................................................................................................................................(2)

Energy Storage 7
Where Pelec is electrical power in watts, H is the head pressure, Q is the quantity of water and η is the
efficiency of the operation of the system. It is clear from the above equation that the electrical
power can be increased when the head pressure H and the amount of water Q is increased. And
from the law of energy which goes`` energy can never be created or destroyed but it is transformed
from one form to another,`` the potential energy will be transformed to kinetic energy which is then
employed to generate electrical power (Williams, 2013, p. 122). This can be illustrated using the
below equation (Nelson, 2014, p. 67).
Potential energy = kinetic energy
mgH = ½ mv2 ................................................................................................................................................(3)
Where m is the mass of water, g is the gravitational acceleration, H is the pressure head and v is the
speed of the flowing water (Papers, 2011, p. 89).
In the power house, there is water turbine which is a rotary device for converting the potential
energy and kinetic energy (mechanical energy) to electrical energy. The water is allowed to
approach the blades of the turbine in such a way that the blade will have a continuous movement
with minimum drag and abrasion (Pardalos, 2008, p. 12). This is illustrated in the figure below;

Energy Storage 8
Fig 3: showing the water turbine employed in the generation of electrical energy. (Richard, 2013, p.
105).
The turbine blades are coupled to the generator through the shaft, the generator has the rotor
which has the magnetic field and the stator which has the conductor coiling (Richard, 2013, p. 213).
The absolute velocity at which the water will leave the nozzle to the turbines is given by the
following equation;
C =√2× g × H ....................................................................................................................................................
(4)
And the circumferential speed of the turbine blade is given by the following equation;