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 compressed air energy storage full report
Post: #1

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CAES (Compressed Air Energy Storage)

What is Compressed Air Energy Storage

CAES refers to the compression of air to be used later as energy source.It can be stored during periods of low energy demand (off-peak),inorder to meet periods of higher demand (peak-load).
The first CAES systems were
constructed by Victor Popp in 19-th
centuary That was in 1870.

PARTS

1)Turbo-compressors
2)Turbo-expanders
3)Under ground vessels
4)Turbine & generator

WORKING

Off-peak (low-cost) electrical power is used to compress air into an underground air-storage vessel and later the air is used to feed a gas-fired turbine generator set to generate electricity during on-peak (high-price) times.
High pressured air can be obtained by placing the pressurized air under water in flexible containers (e.g. plastic bags) Due to the limited number of suitable locations, this will becomes expensive, Here the charge and discharge pressures are always constant.

The charging & discharging principle is the IDEAL GAS LOW , PV=nrT
By compaining the GAS LOWâ„¢S such as Boyleâ„¢s law ,Charles law
P is the absolute pressure
V is the volume of the vessel
n is the amount of substance of gas
r is the ideal gas constant
T is the absolute temperature

Storing Wind Power With Compressed Air

How wind power plant can
store the energy by Compressed Air methode
Â¢ Wind power

The major problem of the wind power

is that very fickle.Wind power is created by the unequal heating of land and water by the sun.The difference in temperature gradients causes the circulaton of wind power.This kinetic energy of moving air is converted to electrical energy by using wind mills.

1,Wind energy is free.
2,Wind power plant avoid use of fuels.
3,Unlike solar enegy wind power is available both during day and night,
4,Wind power plants need less time to construct as compared to other power plants

Â¢ When the wind blows during the night (when electricity demand is low), the electricity generated can be used to power an air compressor. The compressed air can then be stored in the underground caves .
During the day when demand peaks the compressed air can be released through a turbine for generating electricity.
Â¢ A CAES operates by means of large electric motor driven compressors that store energy in the form of compressed air in the reservoir.
Â¢ To return electricity to the customers, air is extracted from the reservoir. It is first preheated. The heated air is then mixed with small quantities of oil or gas, which is burnt in the combustor. The hot gas from the combustor is expanded in the turbine to generate electricity.

The Future of CAES with Wind Power

Since electricity from wind turbines with CAES system is more expensive than that generated by conventional power stations, the benefit of storing wind power is that electricity can be exported to the National Grid at peak times of day

Â¢ Advantages of CAES over BATTERY

While batteries can also be used to store energy, they are expensive to make, use hazardous and toxic metals and compounds, and canâ„¢t hold energy for very long.
CAES donâ„¢t need any costly installations
The overall efficiency of this system
is 75%.

Its losses are very small. A CAES system can be used to store energy for more than a year.
Fast start-up is also an advantage of CAES. A CAES plant can provide a start-up time of about 9 minutes for an emergency start, and about 12 minutes under normal conditions.

CONCLUSION

A CAES inconjunction with gas
plant helps to reduce the use of gas

As we are constructing more wind farms with CAES system we can reduce our dependence on the electricity.
Post: #2
Post: #3
Compressed air energy storage
Compressed Air Energy Storage (CAES) is the term given to the technique of storing energy as the potential energy of a compressed gas. The usual technique is to pump air into large storage tanks or naturally occurring underground formations. Today , its main application is in solving the intermittency problems associated with wind turbine electrical generators. air compressors are run when the energy is available and they pump air into the storage cavern. conventional gas turbine expanders are used to expand the gas when the need arises.

ancillary services provided to the grid is the main advantage of CAES. peak shaving; spinning reserve; VAR support; and arbitrage etc are the various applications. energy from several sources can be stored and recovered at a later time.

losses are there as there is energy conversion. General Compression (using the wind turbine to compress the air directly) is used as a way to solve this problen to a certain extent. additional heating in the expansion process causes most of the inefficiency and can be seen as the disadvantage in CAES, which is even severe if fossil fuels are used for the heat addition.

Practical constraints in transportation
Comparison with batteries
Advanced fiber-reinforced bottles are comparable to the rechargeable lead-acid battery in terms of energy density. They can be far better because of constant voltage output over entire discharge period but in CAES, the voltage varies greatly with air pressure.
very high flux rate energy transfer can be done with CAES, which maybe particularly advantageous for hybrid vehicles.

visit these links for further details and report:

http://coen.boisestate.edu/WindEnergy/re...07-001.pdf
http://www.dresser-rand.com/literature/g...0-CAES.pdf
http://en.wikipedia.org/wiki/Compressed_...gy_storage
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