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Energy storage Devices
Background
Storage devices are an essential units that stores electric
energies produced by different manners.
Storage devices takes an important part in the electricity
storage systems for households, the medium-size system
for industrial/commercial use, and the extra-large system
for power plants and substations.
DIFFERENT ENERGY GENERATION AND
STORAGE TECHNOLOGIES
•
•
•
•
•
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Pumped storage
Batteries
Superconducting magnet energy storage
Flywheel energy storage
Regenerative fuel cell storage
Compressed air energy storage
Pumped storage
Hydroelectric Power Plant
In a pumped storage hydro plant, water is
pumped during off-peak times and may be
utilized to generate electricity. Hydro power
plant store electricity in Megawatts (MW)
or even Gigawatts (GW).
 In hydroelectric power station potential and kinetic energy of stored
water is converted into electric energy.
 For hydro power station factors like rainfall,steam flow available
head and storage are very important.
 25% of electricity generation capacity in world is provided by
hydel power plant.
 In India 25.32% of total electricity generation capacity is produced
by hydel power plant.
BASIC ELEMENTS OF HYDEL POWER PLANT
ADVANTAGES OF HYDEL POWER PLANT
• This plant is free from pollution.
• Its operation and maintenance cost is less.
• Unit cost of power is less.
• Hydraulic turbines can be started speedily.
• The plant has longer service life.
• No fuel is required.
Disadvantages of hydel power plant
• Initial cost of dam and plant is high.
• The availability of power from it is not much
reliable.
• Loss of forest creates environmental problems.
• Due to evaporation , considerable water is lost.
• Time required for construction of hydro project is
more.
Batteries
A mobile source of power that makes many modern
conveniences possible.
History behind this storage concept
In ancient times, the generation of electricity was purely
accidental.
By rubbing certain materials together, static charges can be
accumulated.
Ancient Greeks rubbed amber on hair to generate electricity.
In fact, the word elektron comes from the greek word for
amber By the mid 1600’s, static electricity could be readily
generated by rubbing insulating materials together: fur/cloth,
sulfur, amber, etc.
But in the 1600’s, scientists did not really know much about
electricity or how to use it.
In 1745, scientists (Musschenbroek and Cunaeus) noticed that
one could “charge” up a glass filled with water and get a
shock by touching a metal nail Shortly thereafter, this was
simplified to just metal foil wrapped around the inside and
outside of a jar with a chain connecting the inner layer.
Leyden Jar
We know these devices as capacitors, but they work by
storing charge ELECTROSTATICALLY
1746: Nollet assembled a line of 200 monks each holding the end of a
wire to test if electricity can travel faster than human communication.
Without warning he connected a Leyden Jar to
the ends …
1747-1753 Cavendish used Leyden Jars to discover many of the
fundamental physics laws of electricity
Inverse square law for force, electric potential, capacitance, resistance
But he could not published all his study and these discoveries were
rediscovered by Faraday, Ohm, Coulomb, Maxwell
1786: Galvani’s famous experiments on frog legs
He took two dissimilar metals (Zn, Cu) and touched them to the
ends of a dead frog’s leg and surprisingly, the leg moved and Galvani
attributed this to bioelectricity
But the scientist, Volta did not believe that the
electricity came from the frog.
He believed the electricity came from the
metals.
In 1799, Volta tried a experiment by combining different metals that are
separated by a salt or acidic solution it was possible to generate
electricity.
First commercially
available battery
How does all of this work ?
It’s all electrochemistry!!
The redox (oxidation-reduction) reactions that occur at
these electrodes convert electrochemical energy into
electrical energy.
For today, we’ll focus on batteries for portable
energy storage
1.Introduction
Batteries definition:
Two or more electrochemical cells, electrically
interconnected, each of which contains two electrodes and
an electrolyte.
In everyday usage, 'battery' is also used to refer to a single
cell. The solid-state batteries are the batteries in which the
electrolyte is in solid state, which is responsible for the
conduction of ions from one electrode to other electrode.
In 1800, Alessandro Volta invented the first modern battery.
There are two common types of batteries
1. Primary
The materials inside
the battery were the
prime source of the
electric power it
delivered.
2. Secondary
First it had to receive a
charge before they could
deliver any power. It
also
called
as
Rechargeable batteries.
1. Primary batteries
In primary batteries, the electrochemical reaction is not reversible.
During discharging the chemical compounds are permanently
changed and electrical energy is released until the original
compounds are completely exhausted.
Thus the cells can be used only once.
2. Secondary batteries
In secondary batteries, the electrochemical reaction is reversible and
the original chemical compounds can be reconstituted by the
application of an electrical potential between the electrodes injecting
energy into the cell.
Such cells can be discharged and recharged many times.
Fundamental of Cells
If there is a spontaneous chemical reaction then the generated chemical
energy can be further used to do some useful work.
To exploit this energy, the reaction must be split into two separate parts
reactions:
1. Oxidation
2. Reduction
The reactions will be into two different containers and a conductive
wire is used to drive the electrons from one side to the other.
In doing so, a Voltaic/ Galvanic Cell is created.
Fundamental of Cells
continues
In case of general Voltaic/ Galvanic Cell the redox reactions which
include all chemical reactions in which atoms have their oxidation
state changed;
Such reactions involve the formal transfer of electrons
A net loss of electrons
Oxidation
A net gain in electrons
Reduction
increase in oxidation The decrease in oxidation
state of an atom through a chemical state of an atom through a
The
reaction
chemical reaction.
Daniell cell,
Copper and Zinc electrodes are immersed in a solution of copper
sulfate and zinc sulfate respectively.
At the anode, zinc is oxidized as per the following half reaction:
Zn(s) → Zn2+(aq) + 2e-
(Required energy for this reaction : -0.76 volt)
At the cathode, copper is reduced as per the following reaction:
Cu2+(aq) + 2e- → Cu(s) (Required energy for this reaction : 0.34 volt)
The total reaction being:
Zn(s) + Cu2+(aq) → Zn2+(aq) + Cu(s).
Net delivered Energy ENET = E (Cu2+ / Cu ) - E (Zn2+ / Zn )
= 0.34 - (-0.76) Volt
=1.1 Volt
Batteries have become a most important and most used
equipment in these days. Batteries are used where power
supply is not regular, where low voltage is required like
watches, mobiles many small equipments which require
lesser voltage mainly run on batteries.
The main advantage of batteries are that they can be charged
and used if the capability of supplying power reduces. Cells
are the unit of batteries, many cells complete a battery.
There are mainly two types of batteries,
I) Alkaline batteries
II) Lead-acid batteries
The first Alkaline battery was brought into market by Eveready
Battery, Toronto.
It was developed by Lew Urry in 1949, one of the chemical engineer
in the same company.
Alkaline batteries in the starting was five to eight times as long as
zinc-carbon cells, their predecessors.
Alkaline Batteries
In any kind of batteries, electrolysis has very important role
of running of a battery. Electrolysis means basically
chemical reaction while conducting current through a
mixture. The alkaline Batteries are basically introduced to
overcome the weight and mechanical weakness of the lead
plates.
Alkaline battery is so named because the
electrolyte used in it is potassium
hydroxide, a purely alkaline substance
The main working principle of the alkaline batteries is
based on reaction between zinc (Zn) and manganese dioxide
(MnO2).
Construction of Alkaline Battery
Construction:
The body of the battery is made of a hollow steel drum. This drum
contains all materials of the battery and it also serves as cathode of the
battery. The positive terminal of the battery is projected from the top
of this drum.
Fine grained manganese dioxide (MnO2) powder mixed with coal dust
is molted to the inner peripheral surface of the empty cylindrical drum.
This molded mixture serves as cathode mixture of the alkaline battery.
The inner surface of the thick layer of cathode mixture is covered with
paper separator.
The central space, inside this paper separator is filled by zinc powder
with potassium hydroxide electrolyte. The zinc powder serves as
anode.
The paper separator soaked with potassium hydroxide, holds the
electrolyte in between cathode(MnO2) and anode(Zn).
A metallic pin (preferably made of brass) is inserted along the central
axis of the alkaline battery to collect negative charge. This pin is
called negative collector pin. This pin is in touch with metallic end
sealed cap.
There is a plastic cover just inside the Metallic end sealed cap and this
plastic cover electrically separates positive steel drum and negative
end cap of alkaline batteries.
In an alkaline battery cell, the powder zinc serves as anode,
manganese dioxide serves as cathode and potassium hydroxide serves
as electrolyte.
An alkaline battery cell is rated for 1.5 V. A new non
discharged alkaline cell shows a voltage of 1.50 to 1.65 V.
The average voltage under load condition may be 1.1 to 1.3
V. AA alkaline cell is generally rated for 700 mA.
There are various types of alkaline batteries depending on various
parameters. Depending on the composition of the active materials of
the plates there are four types of batteries.
a) Nickel iron (or Edison)
b) Nickel- cadmium (or Nife)
c) Silver zinc
d) Alkum batteries
Use of Alkaline Batteries
Various types of these batteries are there and different batteries are
used for different purposes. Like, nickel iron batteries are used for
propulsion of industrial trucks and mine locomotives. In air conditions
also, this type of batteries are used. Another type of batteries alkaline
battery is Nickel-cadmium batteries, they are used in commercial
airlines, military aeroplane for initiating main engine. So, we can say
that the alkaline batteries are mainly used in moving vehicles and
industrial purposes.
Lithium battery
•
Lithium is the lightest of metals and it can float on water.
•
The electrochemical properties of lithium are excellent
and it is also a highly reactive material.
•
These properties gives Lithium the potential to achieve
very high energy and power densities in high-density battery
applications such as automotive and standby power.
•
Lithium batteries are primary batteries in which lithium
metal (or) lithium compound acts as a Anode. A lithium
cell can produce voltage from 1.5 V to about 3 V based on
the types of materials used.
37
Characteristics
They use nickel hydroxide Ni(OH)2 for the positive electrode
(cathode), cadmium Cd as the negative electrode (anode) and an
alkaline potassium hydroxide KOH electrolyte.
Their small size and high rate discharge capacity made portable tools
and other consumer applications practical for the first time.
The cells are sealed and utilise a recombinant system to prevent
electrolyte loss and extend the useful life.
There are two types of lithium-based batteries available.
1. Lithium batteries
2. Lithium-ion batteries
•
In lithium batteries, a pure lithium metallic element is
used as anode. These types of batteries are not
rechargeable.
•
In lithium-ion batteries, lithium compounds are used
anode.
as
These batteries are known as re-chargeable batteries. Therefore,
Lithium ion batteries are
considered as best than pure Lithium
based batteries.
39
Lithium-ion battery (Li-ion Battery)
Li-ion batteries are secondary batteries.
• The battery consists of a anode of Lithium, dissolved as ions, into a
carbon.
• The cathode material is made up from three electro-active oxide
materials,
•
•
•
Lithium Cobalt-oxide (LiCoO2 )
Lithium Manganese-oxide (LiMn2 O4 )
Lithium Nickel-oxide (LiNiO2)
40
Principle
During the charge and discharge processes, lithium ions are inserted
or extracted from interstitial space between atomic layers within the
active material of the battery.
• Simply, the Li-ion is transfers between anode and cathode through
lithium Electrolyte.
41
Anode
Cathode
Li- ion Electrolyte
Li-Ion battery Principle
Construction
•
Li-ion cell has a four-layer structure.
•
A positive electrode made with Lithium Cobalt Oxide
has a current collector made of thin aluminum foil cathode
•
A negative electrode made with specialty carbon has
a current collector of thin copper foil – anode
•
A separator is a fine porous polymer film.
•
An electrolyte made with lithium salt in an organic
solvent.
Construction cont..
•
The electrolytes are selected in such a way that there
should be an effective transport of Li-ion to the
cathode during discharge.
•
The type of conductivity of electrolyte is ionic in
nature rather than electronic
Working
The traditional batteries are based on galvanic action but
Lithium ion secondary battery depends on an
"intercalation" mechanism.
This involves the addition of lithium ions into the crystalline
lattice of the host electrode without changing its crystal
structure.
These electrodes have two key properties. One is the open
crystal structure, which allow the insertion or extraction of
lithium ions and the second is the ability to accept
compensating electrons at the same time. Such electrodes
are called intercalation hosts.
Working Cont…
The chemical reaction that takes place inside the battery is as follows,
during charge and discharge operation:
The lithium ion is inserted and exerted
into the lattice structure of anode and
cathode during charging and discharging
During discharge current flows through
external circuit and light glows
During charging, no the electrons flows
in the opposite direction
48
• During charging, lithium in positive electrode material is
ionized and moves from layer to layer and inserted into the
negative electrode.
• During discharge Li ions are detached from the anode and
migrate across the electrolyte and are
inserted into the
crystal structure of the host compound of cathode.
• At the same time the compensating electrons travel in the
external circuit and are accepted by the host to balance the
reaction.
• The process is completely reversible. Thus the lithium
ions pass back and forth between the electrodes during
charging and discharging.
• Because of this reason, the lithium ion batteries are called ‘
Rocking chair, ‘Swing’ cells.
• A typical Li-ion battery can store 150 watt-hours of
electricity in 1 kilogram of battery as compared to lead acid
batteries can sore only 25 watt-hours of electricity in one
kilogram
• All rechargeable batteries
when stored or not in use.
suffer
from
self-discharge
• Normally, there will be a three to five percent of selfdischarge in lithium ion batteries for 30 days of storage.
5. Advantage, disadvantage and applications
Advantages
• They have high energy density than other rechargeable batteries
• They are less weight
• They produce high voltage out about 4 V as compared with
other batteries.
• They have improved safety, i.e. more resistance to
overcharge
• No liquid electrolyte means they are immune from
leaking.
• Fast charge and discharge rate
Disadvantage
• They are expensive
• They are not available in standard cell types.
PH 0101 Unit-5 Lecture-7
51
Applications
•
The Li-ion batteries are used in cameras, calculators
•
They are used in cardiac pacemakers and other
implantable device
•
They are used in telecommunication
instruments, portable radios and TVs, pagers
•
They are used to operate laptop computers and
phones and aerospace application
PH 0101 Unit-5 Lecture-7
equipment,
mobile
52
Primary batteries are capable of one-time use: use it until it’s depleted
and then dispose of it.
The most common primary batteries are alkaline D, C, AA, AAA and
9-volt batteries.
Applications:
Advantages:
Portable devices
Lighting
Toys
Memory back-up
Watches/clocks
Hearing aids
Radios
Medical implants
Defence related systems such as
missiles
Inexpensive
Convenient
Lightweight
Good shelf life
High Energy density at
low/moderate discharges
Disadvantages:
Can only be used once
Leads to large amount of waste
batteries to be recycled
Batteries put into landfill sites have
severe environmental impact
Continued