Energy Storage System: Presented By: Name: Monalisa Das Roll No: 0521209009 Branch: Electrical & Electronics

ENERGY STORAGE SYSTEM PRESENTED BY : NAME: MONALISA DAS ROLL NO: 0521209009 BRANCH: ELECTRICAL & ELECTRONICS

INTRODUCTION • Energy is useful only when it is available when and where wanted. • Keeping the energy available until it is wanted is called STORAGE. • Energy storage is important for power leveling for the power companies.

ENERGY STORAGE SYSTEM

• Generating stations operate more efficiently if they run at constant output level. But the demand of a power station is not constant always. • When the supply exceeds the demand, the extra amount of energy should be stored in recoverable Energy storage must consider both the amount of energy that can be stored and the efficiency at which it can be recovered. • So the materials chosen for this purpose should have high energy storage capacity and high rate of recovery. • And one of the main point is it should be ecofriendly form.

TYPES OF ENERGY STORAGE SYSTEM Methods for energy storage may be classified according

to the form in which energy is stored. The categories are: 1. Mechanical Energy Storage: Pumped hydroelectric storage Compressed air storage Flywheel 2. Electrical Storage: Lead acid battery 3. Chemical Energy Storage: Hydrogen Ammonia Reversible chemical reactions 4. Electromagnetic Energy Storage 5. Thermal Energy Storage Sensible heat Latent heat Chemical reactions I will be focusing only on mechanical energy storage……..

Mechanical Energy Storage Pumped hydroelectric storage: • It is a method of storing and producing electricity to supply high peak demands by moving water between reservoirs at different elevations. • Electric power is used to pump water from a supply at a lower level to a reservoir at a higher level. When the power demand exceeds the supply, the water is allowed to flow back down through a hydraulic turbine which drives an electric generator.

Characteristics • In these systems a reversible pump-turbine or motorgenerator set is a principal piece of equipment. • The efficiency is 65-75%. • The altitude difference between upper and lower levels in pumped storage facility ranges from 30 m to 300 m. • Francis type reversible turbines are used for higher head and propeller type turbines are used for low heads. • There are also underground pumped hydro systems. The upper reservoir is at or near ground level. The lower reservoir is placed underground. This type of system overcomes the requirement of suitable topography. • This system is a potential energy storage system suitable for large utility energy storage.

Advantages: • Relatively low capital cost. • It is a rugged and dependable storage plant. • Adoptable to automation. • Free from effects of environmental pollution and maintenance is very less

ompressed air storage: • In compressed air energy storage, offpeak power is taken from the grid and is used to pump air into a sealed underground cavern to a high pressure. • The pressurized air is then kept underground for peak use. • When needed, this high pressure can drive turbines as the air in the cavern is slowly heated and released, the resulting power produced may be used at peak hours.

OPERATION • Electric power in excess of the immediate demand is supplied to the motor which drives the compressor. • The compressor compresses the air. The compressed air at about 70 atm is stored in a suitable reservoir. • The air is heated during compression and may have to be cooled prior to storage to prevent damage to the reservoir walls. • When additional power is needed to meet the demand, the compressed air is released and heated using gas or oil fuel. • The hot compressed air is then expanded in a gas turbine connected to the generator. • Thus electricity is generated and used during peak demand times.

Advantages: • Can be used on very large scales. • High storage capacity.i.e. 15 -300 MW. • The storage period is also the longest due to the fact that its losses are very small. • Fast start-up is also an advantage

The Huntorf plant, located in North Germany, was commissioned in 1978 as the world's first CAS plant. .

Flywheel: • A flywheel is basically a spinning disc with a hole in the middle to be used for rotation. • The basic idea of flywheel energy-storage is to accelerate a suitably designed physical rotor to a very high speed in vacuum as via an electric motor, at which high energy storage densities are achieved. • The energy is stored as kinetic energy most of which can be electrically retrieved when the flywheel is run as a generator. I.e. armature is rotated by the flywheel. • It also includes bearing, a vacuum pump to minimize windage losses, seals to minimize oil and air leakage into the vacuum chamber, a containment ring to protect nearby equipment.

Principle:

Materials used for flywheels Materials for energy storage flywheels must have high tensile strengths, high density ratio, and high resistance . So the materials used are • •

Some alloys- steels Fiber- reinforced plastics

Advantages: • • • •

Long life and high power output. Contains no hazardous chemicals. Flywheels are about 90% efficient. Can be installed anywhere and take up little land area. • Larger storage demands would probably best be met by cascading many such small units.

Applications: 1. The application of flywheels in starting and braking locomotives. 2. Flywheels have been introduced in the market of electric vehicles.

Conclusion: So energy storage is as much important as energy generation. In order to match the supply and demand in time domain we must go for storage system. By many ways we can store energy and can utilize them at the time of need. Here I have discussed only the mechanical energy storage which is used in large scales.

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