These slides presents on introduction to energy storage devices. Later of the class the modelling and control aspects are also going to be presented in some other slides.

1. CLASS-9: ENERGY STORAGE IN SMART MICRO- GRID
Prof. (Dr.) Pravat kumar Rout
Department of EEE,ITER
Siksha ‘O’ Anusandhan
(Deemed to be University),
Bhubaneswar, Odisha, India
Subhasis Panda
(Research Scholar)
Department of EE,ITER
Siksha ‘O’ Anusandhan
(Deemed to be University),
Bhubaneswar, Odisha, India
Course: Distribution Generation and Smart Grid

2. INTRODUCTION
➢ Primary functions are
1. Deliver short-term power in KW (like power quality, voltage support and frequency
support services)
2. Supplying energy for a long period in kwh
3. Support for renewable energy (many RER are intermittent, generating whether dictates rather
than energy demand dictates )
4. Support to FACTS Devices for active power support and enhancing dynamic performance
5. Many transportation systems require energy to be carried with the vehicle

3. TYPICAL ESS CONFIGURATION

4. CONFIGURATION FOR SMARTER ESS

5. MAJOR APPLICATION
1. Power quality (used to mitigate the short term loss of power and power fluctuations, can be
used to mitigate voltage fluctuations and improves power quality issues such as harmonics )
2. Service provision to renewable generation (support by smoothing their output, matching
contract positions and shifting the generated energy in time, also supplying the energy deficit and
absorbing the excess)
3. Electrical Energy time shifting (involves storing energy when demand or price is low)
4. End use energy management (energy management at the customer premises)
5. Voltage support (voltage is maintain within limit )
6. Reserve ( to ensure system stability and reliability )
7. Load flowing (to follow frequently changing power demand)
8. Capacity of distribution circuits (used to relieve the congestion of distribution circuits)

6. PARAMETERS FOR SELECTION OF PROPER STORAGE
TECHNOLOGY
❖ Unit size (Scale of technology, storage technologies have an associated range for applications )
❖ Storage Capacity(Total store of available energy after charging)
❖ Available Capacity (Average value of power output based on the state of charge/depth of discharge)
❖ Self discharge time (Time required for a fully charged, non-interconnected storage device to reach a certain
depth of discharge (DOD), this is contingent on the operational condition of the system )
❖ Efficiency (Ratio of energy output from the device to the energy input issue of conversion technology )
❖ Durability or life cycle (Number of consecutive charge-discharge cycles a storage installation can undergo
while maintaining the installations and other specifications within limited ranges)

7. PARAMETERS FOR SELECTION OF PROPER STORAGE TECHNOLOGY
… CONTINUE
❖Autonomy (Ratio between energy capacity and maximum discharge power; indicates the maximum amount
of time the system can continuously release energy)
❖ Mass and volume densities (Amount of energy accumulated per unit mass or volume of the storage unit )
❖ Cost(Cost of installation, operation and maintenance of storage technology; cost should be analyzed
through out system life span)
❖ Feasibility (Degree of adaptability to the storage applications)
❖ Reliability (Guarantee of service )
❖ Response time for energy release and operational constraints

8. ENERGY STORAGE TECHNOLOGIES
❑ Flow batteries
❑ Advanced Batteries
❑ Super capacitors
❑ Super Conducting Magnetic Energy Storage
❑ Pumped Hydro
❑ Compressed Air
❑Flywheels

9. BATTERIES
❖ A battery is a device that produces electrical energy from the chemical reactions
❖ There are different kinds of batteries with different chemicals
❖ The idea behind them is that the two different chemicals within a battery cell have
different loads and are connected with a negative (cathode) and the other with a
positive electrode (anode). When connected with an appliance the negative electrode
supplies a current of electrons that flow through the appliance and accepted by the
positive electrode.
❖ For the use of storing energy produced by renewable energy sources only
rechargeable batteries are relevant and will be considered.

10. BATTERIESBATTERIES

11. FLOW BATTERIES
• 1. Similar to lead acid batteries but the electrolyte is stored in a external container
and it circulates through the battery cell stack
• 2. Flow batteries use pumped electrolytes that move outside of the battery case
• Polysulfide Bromide (PSB), Vanadium Redox (VRB), Zinc Bromine (ZnBr), and
Hydrogen Bromine (H-Br) batteries are examples
• 3.A “filling station” could exchange spent electrolyte for new “charged” electrolyte
• 4. The power and energy ratings are thus independent since the power is from the
battery electrodes while the electrolyte may be replaced periodically

12. FLOW BATTERIES

13. FLOW BATTERIES… CONTINUE
ADVANTAGES
1. Unlimited electrical storage
capacity, Only limitation is the
size of the electrolyte storage
reservoir
DISADVANTAGES
1. Limited number of cycles of
uses, after three to five years
the system has to changed

14. ADVANCED BATTERIES
• Advance batteries include lithium ion, polymerion, nickel metal hybrid and sodium sulfur type

15. ADVANCED BATTERIES….CONTINUE
ADVANTAGES
1. Use less space than lead acid
battery
DISADVANTAGES
• 1. Too expensive for large scale
applications

16. SUPER CAPACITOR
• Electronic device with the capacity to provide high power and energy which
have the characteristics of capacitor and electrochemical batteries except
there is no chemical reaction

17. SUPER CAPACITORS…CONTINUE
ADVANTAGES
• 1.Virtually unlimited cycle life
• 2. Low impedance
• 3. Rapid charging
• 4. Simple charge methods
DISADVANTAGES
• 1. Linear discharge voltage prevents use
of the full energy spectrum
• 2. Low energy density
• 3. Cells have low voltages
• 4. High self-discharge

18. SUPER CONDUCTING MAGNETIC ENERGY
STORAGE (SMES)
❖ The system consists of three major components: the coil, the power conditioning system, and
a cooling system
❖ The idea is to store energy in the form of an electromagnetic field surrounding the coil, which
is made of a superconductor.
❖ At very low temperature, some materials loose every electric resistance and thus becomes
superconducting. The superconducting magnetic storage system (SMES) makes use of this
phenomena and in theory stores energy without almost any energy loss (practically 90-95 %
efficiency)

19. SUPER CONDUCTING MAGNETIC ENERGY STORAGE
(SMES)… CONTINUE
❖ However, since relevant superconducting materials are only known to work
below – 253 degree centigrade (c) (20 degree kelvin), [niobium-titanium -264
degree centigrade 9 degree kelvin; niobium-tin -255 degree centigrade 18 kelvin]
a system to cool the components down to those temperature is required.
❖ This can be accomplished by liquefying helium; but, it is very expensive and the
process lowers the efficiency, especially in stand-by-mode.

20. Components of Super Conducting Magnetic Energy
Storage (SMES)

21. CONCEPTUAL DESIGN OF A SUPERCONDUCTING COIL

22. SUPER CONDUCTING MAGNETIC ENERGY
STORAGE (SMES)
ADVANTAGES
1. Power is available almost instantaneously
2. High power output for brief period
3. No loss of power
4. No moving part
5. Fast respond time
6. Capable of partial and deep discharges
7. No environmental hazard
DISADVANTAGES
1. Energy content is small and short lived
2. Cryogenic, cold temperature technology can be
challenging
3. High energy losses (approximately 12 percent
day)
4. Very expensive in production and maintenance
5. Reduced efficiency due to the required cooling
process

23. PUMPED STORAGE HYDROELECTRICITY
❖ When you lift an object a certain mass you overcome gravity. In order to do so you
must supply a force over a height. The force required to lift is defined by the physical
law F = m*a (m is the mass and a for acceleration), but in this case a is replaced by g
for the gravitational acceleration (9.81 meters per square second)
❖ The work, meaning the energy supplied and therefore stored in the object is defined
by W = F*d (in this example the term d for distance can be replaced by h for
height)
❖ This results in W = m*g*h, meaning the energy stored equals the mass multiplied
by the gravity and the height.

24. CONTINUE…
❖ The PSH plant puts this math into practice.
❖ Basically, the system contains two water reservoirs at different elevations. In times of low
electricity demand and high production, water is pumped from the lower reservoir into the
higher, storing the electricity in the water in the form of potential energy. When needed , for
example on peak demand, the water can be released, flowing down the pipes again and back
through the turbine which then generates the electricity.
❖ The general formula for the power output is P = Q * h* eta * g *rho, including the factors
of volume flow rate passing the turbine (Q) , the hydraulic efficiency of the turbine (eta) and
the density of the water (rho )

26. HYDRO PUMPED STORAGE
1. Special turbines can run either to spin an alternator or to act as a pump
2. This reversibility allows excess electrical energy to be used to pump water to a higher
storage reservoir to be used as an energy source later
3. Since 2.31 ft of elevation has a bottom pressure of one pound per square inch (psi), a
head height of 200 ft is equivalent to 86 psi
4. Japan built a 30MW seawater pumped hydro system atYanbaru in 1999
5. Worldwide, pumped hydro is about 90GW, ~3% of total storage, the most widespread
high-energy storage technique
090331

27. PUMPED HYDRO STORAGE
ADVANTAGES
1. Readily available and widely used in high power
application
2. Lower cost of power, frequency regulation on the grid,
and reserve capability
3. Fast response time
4. Inexpensive way to store energy
5. High overall efficiency (70-80 )
6. Mature technology, capable of storing huge amount of
energy
DISADVANTAGES
1. Spends years in regulatory and environmental review
2. Can only be implemented in areas with hills that is few
potential sites
3. Huge environmental impacts
4. Requires a significant huge water source

28. COMPRESSED AIR PUMPED STORAGE
❖ CAES plants store energy in form of compressed air.
❖ Only two plants of this type exist worldwide. The first one built
over 30 years ago in Huntorf, Germany with a power output of 320
MW. The second one is located in McIntosh, Alabama, USA and
began operation with a 110 MW output and 2860 MWH of storage
capacity. Both are till in operation
080331 http://unisci.com/stories/20013/0802016.htmhttp://www.caes.net/mcintosh.html
http://www.acfnewsource.org/science/energy_mine.html

29. CONTD…..
❖ The basic idea is to use an electric compressor to compress air to a
pressure of about 60 bars and store it in giant space to power a turbine
to generate electricity again when demanded. These storage are sealed
airtight as proved by the existing two plants and have also been used to
store natural gas for years now. When the air is released from storage,
it expands through a combustion turbine to create electricity.
080331 http://unisci.com/stories/20013/0802016.htmhttp://www.caes.net/mcintosh.html
http://www.acfnewsource.org/science/energy_mine.html

31. COMPRESSED AIR ENERGY STORAGE
ADVANTAGES
1. Conserve some natural gas by using low
cost, heated compressed air to power
turbines and create off-peak electricity
2. inexpensive way to store energy
3. Fast response time
4. Capable of storing huge amounts of
energy, similar to PSH
DISADVANTAGES
1. low efficiency due to the extra reheating energy needed to
turn on the turbine
2. for every KWH of energy going in, only 0.5 kwh of energy
can be taken out
3. Not yet fully developed
4. Competing against other storage needs (natural gas and
hydrogen)
5. Economical only up to a day of storage
6. requires sealed storage caverns

32. FLY-WHEELS: BASIC CONCEPTS
❖ Basically flywheel is disk with a certain amount of mass that spins, holding kinetic
energy. A cylinder that spins at a very high speed, storing kinetic energy
❖ Example:Toy cars that kept going after spinning there wheels
❖ Modern high-tech flywheels are built with the disk attached to a rotor in upright
position to prevent gravity influence. They are charged by a simple electric motor
that simultaneously act as a generator in the process of discharging.
❖ The spinning speed for a modern flywheel reaches up to 16000 rpm and offers a
capacity up to 25 kwh, which can be absorbed or injected almost instantly.

34. FLYWHEELS
ADVANTAGES
1. Low maintenance and long lifespan: up
to 20 years
2. Almost no carbon emission
3. Fast response time
4. No toxic components
DISADVANTAGES
1. Power loss faster than for the batteries
2. High cost
3. Low storage capacity
4. High self discharge (3-20 percent per hour )

35. CONCLUSION: COMPARISON OF SEVERALTYPICAL
ENERGY STORAGE DEVICES
Types Efficiency(%) Energy
density
(Wh/Kg)
Power
density
(W/Kg)
Response
time
(ms)
Cycle life
(time)
Cost
($/kW h)
Battery 60-80 20-200 25-1000 30 200-2000 150-1300
SMES 95-98 30-100 1e4-1e5 5 1e6 High
Flywheel 95 5-50 1e3-5e3 5 >20000 380-2500
Super Cap 95 <50 4000 5 >50000 250-350
NaS 70 120 120 <100 2000 450

36. REFERENCES
• Tan, X., Li, Q., & Wang, H. (2013).Advances and trends of energy storage technology in
microgrid. International Journal of Electrical Power & Energy Systems, 44(1), 179-191.
• Ferreira, H. L., Garde, R., Fulli, G., Kling,W., & Lopes, J. P. (2013). Characterisation of electrical
energy storage technologies. Energy, 53, 288-298.
• Baker, J. (2008). New technology and possible advances in energy storage. Energy Policy, 36(12),
4368-4373.
• Ribeiro, P. F., Johnson, B. K., Crow, M. L.,Arsoy,A., & Liu,Y. (2001). Energy storage systems for
advanced power applications. Proceedings of the IEEE, 89(12), 1744-1756.
• Castillo,A., & Gayme, D. F. (2014). Grid-scale energy storage applications in renewable energy
integration:A survey. Energy Conversion and Management, 87, 885-894.

37. QUESTIONS
• State the functions of storage system in smart grid ?
• State and explain different types of storage technologies in smart grid?
• Compare several typical Energy Storage Devices used in smart grid?