A technical presentation on CAES, a solution to intermittent source of energy such as wind and solar.

1. COMPRESSED AIR ENERGY STORAGE
670064358
Sharath kumar
ENEM102
ADVANCE ENERGY STORAGE

2. CAES can address the vast market disruption and system
risk caused by the mass build-up of renewable energy.
WHY IS THE NEED ?

3. • Compressed air energy storage works like a battery
which temporarily stores energy in the form of
compressed air which is driven electrically.
• Regarded as air pumped into large storage tanks or
any naturally occurring underground formations
aquifers.
• It has gained special status recently as a means of
addressing the intermitting problems associated
with wind turbine electrical generators.
• Air is compressed to about 100bar which is 35%
more pressure than a car tyre.
What is CAES

4. COMPONENTS OF CAES
 Compressor train.
 Motor-generator unit.
 Gas turbine.
 Underground compressed air.

5.  Air is compressed using electricity from the grid. A few ways of doing this is wind, wave or any
transient renewable energy system.
 This air is stored in the usually in salt caverns or in small scales stored in storage vessels.
 The air can be stored in three ways :
1. Diabatic
2. Adiabatically
The air may be pressurized diabatically by pumping air into dry cavern.
Adiabatically, by storing heat generated during compression which is usually stored in heat accumulators.
TYPESOF CAES

6. DIABATIC CAES
 The plants in Huntorf, Germany, and in McIntosh, Alabama, USA,
as well as all the new plants being planned in the future are based
on the diabatic method.
 A Diabatic Compressed Air Energy Storage System is an energy
storage system based on the compression of air and storage in
geological underground voids.
 During operation, the available electricity is used to compress air
into a salt cavern at depths of hundreds of meters (typically 500-
800m) and at pressures of around 100 bar (depth dependant).
 When the stored energy is needed, the released air is heated via
combustion using natural gas or fuel and is expanded in order to
drive a gas turbine to generate electricity.

7. PERFORMANCE OF D-CAES
Power range Upto 100 MW
Energy range 100 MWh to 10 GWh
Discharge Time Upto 10 hours
Life 30 years
Reaction time Few minutes
Efficiency Approximately 55%
CAPEX Energy Approximately 50-150 $/kWh
CAPEX Power 400-1200 $/kW

8. Adiabatic CAES
 Adiabatic means additional use of the compression heat to increase efficiency.
 When the air is compressed, the heat is not released into the surroundings but mostly
captured in a heat-storage facility.
 During discharge, the heat-storage device rereleases its energy into the compressed air, so
that no gas co-combustion to heat the compressed air is needed.
 The object is to make efficiencies of around 70% possible.

9. VARIANTS OF CAES
AA CAES
 When AA CAES is operated at the expansion mode by integrating a
thermal Energy storage system, compressed air energy is converted into
electrical power output without a combustion process involved. The main
benefit of AA CAES is zero carbon emissions. Heat exchanger is used to
cool airflow through compressors and heat input airflow to each turbine.
The overall efficiency of AA CAES is higher than that of the conventional
CAES.
SMALL SCALE CAES
 A small scale CAES facility can use over ground cylinders with suitable
dimensions as a storage facility. Stored facility can either be on site
compression facility or delivered as prefilled high-pressure air cylinders.
Turbines in these CAES need to have high efficiency, fast response and
low maintenance.
LAES
 A variant of CAES, using am electrical machine to drive an air liquefier
and the resultant liquid air is stored in insulated tank at atmospheric
pressure. During discharge, the liquid air is released and pumped to high
pressure, and then vaporized and heated to ambient temperature. This
resultant high pressure gaseous air is used to drive the turbine and
generate electricity.

10. • Artificially constructed salt caverns in deep salt formations are highly preferred. Geologic porous rock formations offer
the most widespread availability and potentially the lowest cost.
• High flexibility, low pressure losses within the storage, no reaction with the oxygen in the air are some desirable
characteristics of salt caverns.
• Natural aquifers are another alternating option; however, it must be taken care that rock and microorganisms do not react
with oxygen. Otherwise, it could lead to oxygen depletion or the blockage of the pores spaces in the reservoir.
• Depleted natural gas fields are also one of the futuristic options for compressed air storage.
• Mixing of Residual hydrocarbons with compressed air is also one other challenges to be addressed.
STORAGE TYPE

11. • One of the central applications for CAES is for the storage of wind energy during abundance and
generation onto the grid during times of shortfalls in wind output.
• Such wind balancing applications require not only large-scale, long duration storage but a quick
response times and siting availability.
• The capital cost of adding incremental amount of storage capacity can be much lower than for other
comparable storage technologies.
• CAES consumes significantly lesser fuel than conventional gas turbine per unit of energy delivered.
Greenhouse effect emissions from wind/CAES systems can be quite low.
WIND INTEGRATED CAES

12.  Located in North Germany.
 Commissioned in 1978.
 Cavern has a storage capacity of 310,000 m3
and runs on a daily charging cycle of 8h
providing a peak output of 290MW for 2
hours.
 The plant has 2 caverns of volume 1,40,000
m3 and 1,70,000 m3 and are at a depth of 650
m and 800 m respectively.
 The system uses 0.8kWh of electricity and
1.6kWh of gas to produce 1kWh of
electricity.
Huntorf,Germany

13. • The McIntosh plant has a
538,000m3 salt cavern at a depth of
450m.
• It provided an output of 110MW for 26
hours until 1998. With addition of two
extra generators its total capacity is now
226MW.
• The power plant incorporates a
recuperator and uses 0.69kWh of
electricity and 1.17kWh of gas to
produce 1kWh of electricity.
McIntosh, Alabama

14. Huntorf McIntosh
2 salt caverns in Huntorf operating at a
high pressure between 4.8Mpa and
6.6Mpa. The plant runs in daily cycle
with 8 hours of compressed air charging
and 2 hours of expansion operation at a
rated power of 290 MW.
The McIntosh facility deploys a heat
recuperator to reuse part of heat energy
from the exhaust of gas turbines thereby
reducing fuel consumption by 22-25%
and improves cycle efficiency from 42%
to 54%.
It has excellent performance statics with
90% availability and 99% starting
reliability. The round-trip efficiency of
this plant is about 42%.
The average running reliability is 96.8%
and 99.5%, average starting reliability is
91.2% and 92.1% during generation and
compression cycles respectively

15. • CAES technology is relatively slow in discharging the
stored power capacity, but has among the highest
system power rating.
• The amount of energy this technology can store in a
large scale system is among the highest of the energy
storage technologies currently available.
• Being relatively slow in the discharge of the stored
energy, this technology can provide energy market
support up to several hours.
• CAES technology can be easily optimized for specific
site conditions and economics.
• CAES plants have fast start-up time. If a CAES plant
is operated as a hot spinning reserve, it can reach the
maximum capacity within a few seconds. The
emergency start-up times from cold conditions at the
Huntorf and McIntosh plants are about 5 minutes.
Their normal start-up times are about 10 to 12 minutes
KEY FEATURES

16. • CAES power plants are a realistic alternative to pumped-hydro power plants.
• The Capital expenditure and operating expenditure for operating diabatic plants are competitive.
• Just as pumped storage, the power can be released almost instantaneously.
• A merit over pumped storage is that the visible impact on the landscape is low.
• The efficiency of the 320MW plant in Germany, Huntorf is about 42% and that in Mcintosh is 54%.
They are 20% less than the efficiency of pumped storage plants. Employ compressed air in gas fired
power plants for regeneration, which limits efficiency and creates emissions.
• Pumped hydroelectric storage is high technical maturity storage technology with an installed total
capacity of 127-129 GW in 2012 and represents around 99% of worldwide bulk storage capacity.
In comparison with other storage systems

17. Technology Capital cost
:capacity ($/kW)
Capital cost
Energy($/kWh)
Hours of storage Total capital cost
($/kW)
CAES( 300MW) 580 1.75 40 650
Pumped
hydroelectric
(1,000MW)
600 37.5 10 975
Sodium sulphur
battery(10MW)
1720-1860 180-210 6-9 3100-3400
Vanadium Redox
battery(10MW)
2410-2250 240-340 5-8 4300-4500

18. • Storeelectric,UK has set up a pilot plant with efficiency 62.3% for a capacity of 40MW
• Expected to reach 68-70% when Scaled to capacity 500MW,21 GWh with possibility of getting to 75-85% with
existing technologies.
• Store electric believes it can achieve a levelized cost of electricity of £100/MWh cheaper than gas fired peaking
plants and levelized cost of storage of 68£/MWh cheaper than hydro.
MATURITY

19. • CAES facility is being planned in Norton, Ohio, USA. This facility will be the largest ever
with a 2700 MW capacity which will compress air to 1500 pounds per square inch (psi) in an
existing limestone mine 2200 feet under ground.
• The university of Chester, UK is building a test facility with a capacity of 200kW.
• 5 caverns located in Cheshire capable of 20MW for 50 hours are planned to be operational
soon. Also, 500MW commercial facility in Cheshire is planned to be operational in 2 years.
• Siemens, PwC, GE are all part of this project.
• The European network Transmission service operators Electricity set up by European
commission has included projects in Cheshire as part of their 10 year development plan and
has officially recognized it as important infrastructure at a continental scale.
RECENT DEVELOPMENTS

20. AREAS OF APPLICATION AND ECONOMICS
• Balancing Energy (supply and demand)
• Higher utilization and greater integration with renewable energy.
• For customers on dynamic rates CAES allows energy arbitrage opportunities.
• Energy storage technologies are currently not uniformly deployed, but will create jobs in
manufacturing and installation as the technology market penetration expands.
• In addition, through energy grid stabilization and smoothening, the technology is
expected to support economic growth objectives.

21. • Cost of a small scale CAES will be extremely expensive.1 million m3 of salt cavern would cost less
than a 1000 m3 cylinder.
• Adiabatic systems require large thermal storage which are massive entailing to high costs and large
parasitic loads.
• The air is stored and used daily and not for a long term. This results in pressure fluctuation which has
consequences on the size and design of the cavern.
• Humidity can lead to more corrosion of the underground bore-hole equipment, the cavern heads,
pipes and fittings.
CHALLENGES

22. • http://wrap.warwick.ac.uk/65595/1/WRAP_Luo_1-s2.0-S1876610214034547-main.pdf
• http://energystorage.org/compressed-air-energy-storage-caes
• https://www.power-technology.com/features/featurecould-air-be-the-next-big-battery-
breakthrough-5864457/
• http://www.climatetechwiki.org/technology/jiqweb-caes
• http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.374.7597&rep=rep1&type=pdf
• https://www.youtube.com/watch?v=K4yJx5yTzO4
• https://www.youtube.com/watch?v=Bj2jTm0PtWw
REFERENCES