This document presents information on various energy storage systems and devices. It discusses smart grid systems which integrate multiple energy sources into a single intelligent electrical network. Batteries are also covered, including primary batteries that cannot be recharged and secondary batteries that are rechargeable. Finally, supercapacitors are examined as an energy storage mechanism that stores electrical charge in an electric double layer at the interface between electrodes and electrolyte, providing high rates of charging and discharging.

1. Prepared By:
Presented By:
Sagar Mali (2067/BEX/133)
Rasu Shrestha (2067/BEX/131)
Sanid Prajapati (2067/BEX/134) Raushan Mahaseth (2067/BEX/132)
Saugat Gautam (2067/BEX/135)

2. INTRODUCTION
 Accumulation of energy for future use
 Accomplished by devices or physical media that stores energy
 Such devices are also known as Accumulators
 To balance the supply and demand of energy
 Major categories are:
 Mechanical
 Electrical
 Chemical
 Biological
 Thermal

3. Energy storing System & Devices
1. Smart Grid Systems
2. Batteries
3. Super Capacitors

4. 1. Smart Grid Systems
 Modernized and intelligent electrical network
 Various energy sources are integrated into single grid
 Acts according to available information & communication technology
 Information gathered may be:
 Behaviors of suppliers and consumers
 Total energy generated
 Total use of energy
 Disturbances and problems within grid
 Currently implemented among European countries

5. System Overview

6. Features of the smart grid
 Reliability
 Fault detection
 Self healing
 Flexibility in network topology
 Distributed generation (from hydropower, solar cells, wind turbines etc)
 Bidirectional energy flow (charging to/from batteries from electric car)
 Efficiency
 Storing energy in off-peak time
 Smart appliances
 Sustainability
 Use of renewable energy sources
 Auto monitor and control system

7. 2. Batteries
 Energy storing device based upon the principle of Electro-Chemical
Reaction
 Converts stored chemical energy directly into electrical energy
 Every battery consists of
 Cathode (+ve terminal)
 Anode (-ve terminal)
 Electrolyte (medium for ions)

8. Principle of Operation
 Each cell is divided to two parts:
 Half cell of cathode and electrolytes
 Half cell of anode and electrolytes
 Cations are reduced (e- are added)




at the cathode during charging
Anions are oxidized (e- are removed)
at the anode during discharge
Basically, Redox reaction powers
the battery
Each half-cell has an Electromotive force (emf), determined by its
ability to drive electric current from the interior to the exterior of the
cell
The net emf is the difference between the reduction potentials of the
half-reactions

9. Types of Batteries
1. Primary Batteries
 Disposable batteries (can’t be recharged) because
• Chemical reactions are not easily reversible
• Materials may not return to their original forms
 Can produce current immediately on assembly
 Most commonly used in portable devices
 Used well away from an alternative power source
 Ex: Zinc–Carbon batteries and Alkaline batteries

10. Types of Batteries
2. Secondary Batteries
 Rechargeable batteries as chemical reaction are reversible
 Charged by applying electric current
 Used for power backup as well as in portable devices
 Example
 Wet cell: Lead- acid batteries
 Dry cell: NiMH, NiCad, Li-ion etc.

11. 3. Super-capacitors
• A type of electromechanical capacitors
• Formerly known as Electric Double-Layer Capacitor (EDLC) or
Ultra-capacitors
• Doesn’t have a conventional solid dielectric
• Can store huge amount of electrical energy
(more energy per unit volume)

12. Energy Storage Mechanism
• Store electrical charge in an electric double layer at the interface
between high-surface-area carbon electrode and liquid electrolyte.
• Double layers are of same substrate and have vanishingly thin (~nm)
• These layers can handle only small P.D so super-capacitors have to be
connected in series to operate in high P.D.
• No need of dielectric layer
permits packing of plates
with large area into
given size resulting in
high capacitances.

13. Comparison of Conventional Storage
Technologies

14. Applications
• Stabilizing the supply of power lines.
• Provides emergency backup to low power devices such as RAM,
S-RAM , Microcontrollers and
PC cards in industries.
• Delivers power for photographic flashes in digital cameras.
• Super-capacitors are used as battery replacement in some pit
trains in China to substitute conventional trolleys in coal mines.
They bring coal to the surface.

15. Super-capacitors as Green Electricity
• Does not contain harmful chemicals for storing charge. Hence,
safe to human.
• High number of charge-discharge lifecycle makes sure of less
number of disposable parts makes it environmentally friendly.

16. Benefits
• Very high rates of charging and discharging.
• Little degradation over hundreds of thousands of cycle.
• Good reversibility.
• Low toxicity of materials used.
• High cycle efficiency( 95% and more).

17. Limitations
• The amount of energy stored per unit weight is considerably
lower than that of an electrochemical battery.
• The voltage varies with the energy stored. To effectively
store
and recover energy requires sophisticated electronic
control and switching equipment.
• Has the highest dielectric absorption of all types of
capacitors.

18. REFERENCES
Websites:
 http://en.wikipedia.org/wiki/Energy_storage
 http://en.wikipedia.org/wiki/Smart_grid
 http://science.howstuffworks.com/environmental/green-science/smartgrid.htm
 http://file.scirp.org/Html/2-6201335/e2908f91-a50c-49e9-a24fa23192a753fc.jpg
 http://en.wikipedia.org/wiki/Battery_(electricity)
 http://electronics.howstuffworks.com/everyday-tech/battery1.htm

19. THANK YOU!