1. Compressed Air Energy
Storage
An Overview by DREAMS Ltd
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2. Overview
 DREAMS Ltd
 CAES Operation
 CAES Examples
 Huntorf, Germany
 McIntosh, Alabama
 Current worldwide CAES Projects
 ADELE Adiabatic Energy Storage Project
 Advantages of CAES
 Conclusions
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3. DREAMS Ltd
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4. CAES Operation
Compression
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Source: http://www.ridgeenergystorage.com/caes_overview.htm

5. CAES Operation
Generation
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Source: http://www.ridgeenergystorage.com/caes_overview.htm

6. Huntorf CAES Plant
 Built in 1978 in Huntorf, Germany as the first CAES
plant worldwide.
 Paired with a Nuclear plant and conventional Natural
Gas Turbine plant.
 Compressed air from cavern mixed with natural gas
and expanded through a turbine to produce electricity.
 One cavern operates diurnally while the other is a
„Black start asset‟, providing protection for a shut-down
of the Nuclear plant.
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Source: http://www.energystorageexchange.org/projects/116

7. Huntorf CAES Plant
 Facts and Figures
 Cavern volumes:
 ≈ 140,000m3
 ≈ 170,000m3
 Total ≈ 310,000m3
 Cavern Depth
 Top – 650m
 Bottom – 800m
 Air Flow Rates
 Turbine – 417 kg/s (Comparatively quick)
 Compressor – 108 kg/s
 Pressure
 Operational Pressure – 70 Bar
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Source: Clean Energy Action Project – Case Study – Huntorf CAES Plant

8. Huntorf CAES Plant
 Facts and Figures
 Power output
 Power – 321,000kW
 Duration – 3 hours
 Energy Output – 963,000kWh
 Cycle efficiency
 46%
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Source: Fritz Crotogino, Klaus-Uwe Mohmeyer and Dr. Roland Scharf - Huntorf CAES: More than 20 Years of Successful Operation

9. McIntosh CAES Plant
 Built in 1992 in McIntosh, Alabama.
 Part of a factory consisting of two conventional gas
turbines.
 Start-up time of 14 minutes when first built.
 Dresser-rand now boast 10 minutes to full power
generation (5 minutes in emergency) and only 4 minutes
to full compression operation.
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Source: Dresser-Rand - CAES
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10. McIntosh CAES Plant
 Facts and Figures
 Cavern volume:
 ≈ 580,000m3
 Cavern Depth
 Top – 450m
 Bottom – 750m
 Pressure
 Operational Pressure – 70 Bar
 Cost
 1991 - $65million = £43million
 Today ≈ $108million = £71million
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Source: Dresser-Rand - CAES
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11. McIntosh CAES Plant
 Facts and Figures
 Power Output
 Power – 110MW
 Duration – 26 hours
 Energy Output – 2,860,000kWh
 Cycle Efficiency
 54%
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Source: Clean Energy Action Project – McIntosh Case Study
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12. ADELE Adiabatic
Storage Project
 Problem:
 Temperature of the air following compression vastly increases, up
to around 600°C which must be dissipated.
 Conversely, thermal energy is lost following air expansion and
hence air must absorb heat before entering the turbine.
 RWE Power, General Electric, Züblin and DLR are currently
researching possible ways to absorb, store and then reuse the
thermal energy in the compressed air.
 They are proposing highly insulated thermal towers made up
stone, gravel and ceramics through which the newly compressed
air will travel, exchanging its thermal energy.
 Before the air from the ground passes into the turbine, it will pass
through this tower absorbing some of the thermal energy, in a pre-
heat operation.
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13. ADELE Adiabatic
Storage Project
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14. ADELE Adiabatic
Storage Project
 Estimated to increase efficiency up to 70%.
 Take the compressed air at 600°C and store the
thermal energy in towers up to 40m high.
 Now delayed pilot plant to be built capable of:
 Storing – 360MWh
 Generating – 360MW electricity
 The equivalent to 50 ultra-modern wind turbines spinning for
4 hours.
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15. Dresser-Rand
 Dresser-Rand have recently been awarded the contract
to proved the equipment for a 317MW CAES system in
Texas, working in partnership with Apex.
 Dresser-Rand also supplied the turboexpander turbines
for the McIntosh CAES plant.
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16. General
Compression Technology
 Have researched and designed the General
Compression Advanced Energy Storage (GCAESTM)
system1.
 Based on reversible thermodynamics, they claim a near-
isothermal process, covering both the compression and
expansion stages.
 Efficiency – 75%
 Cost – $800 - $1000/kW2
 Have a fully operational 100kW multi-stage plant in
Watertown, Massachusetts.
 Construction of second generation GCAES, 2MW, 500MWh
system with wind turbine integration now underway in Texas.
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[1] Source: General Compression – Who We Are
[2] Source: General Compression - Fuel-Free Geologic Compressed Air Energy Storage From Renewable Power - Task #1 Deliverable Report

17. Iowa Stored
Energy Park
 Planned project studied for 8 years to store wind
energy through compression of air in sandstone
aquifers below the ground.
 Power Output: 270MW
 $400million4
 Project terminated in 2011 due to geology reasons.
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[4] Source: Sandia Report – Lessons from Iowa

18. Larne, Ireland
 A planned gas storage system by InfraStrata and North
East Storage that was subject to heavy opposition due
to the disposal of brine in the sea, amongst many other
safety concerns3.
 Gaelectric have now carried out tests to determine the
feasibility of the area for CEAS.
 £175million project
 £10million set aside for feasibility study
 Power Output: 140 - 300MW
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[3] Source: Larne Times – Test Data will Provide Data on Wind-Energy Storage Potential

19. New York Power
Authority Research
 Provide around 25% of the energy requirements of
New York State, and are looking to supply renewable
energy options to all their customers.
 Mission statement:
 “to advance the generation and utilization of renewable
energy through project implementation, research and
technology transfer”8
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[8] Source: New York Power Authority - Energy Storage Activities at New York Power Authorities

20.  Underground CAES feasibility study8
 Power Output: 300MW
 Compressor Power: 215MW
 Storage Capacity: 10 hours
 Cost: $700/kWh
 Above ground CAES feasibility study
 3 foot diameter 2 mile pipework
 Power Output: 10MW
 Storage Capacity: 2hours
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New York Power
Authority Research
[8] Source: New York Power Authority - Energy Storage Activities at New York Power Authorities

21. Norton, Ohio CAES
Project
 This project has been researched for over a decade
now, changing company hands with current owners
First Energy.
 The proposal7:
 CAES in a disused Limestone mine
 Power Output: 270MW initially rising to 2700MW as more
and more phases are built.
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[7] Source: First Energy Corporation – Alternative and Renewable Energy

22. San Joaquin County
CAES Site Testing
 Pacific Gas & Electric Company (PG&E) spent three
weeks conducting tests on a depleted natural gas
reservoir, capable of storing 300MW of power lasting
10 hours5.
 Engineers and geologists have been studying 10m
sections of rock in order to determine the feasibility of
CAES, as has to be the case with all CAES projects6.
 Results are yet to be published.
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[5] Source: Energy Storage Exchange - Advanced Underground CAES Project w/Saline Porous Rock Formation
[6] Source: PGE Currents- Electricity Out of Thin Air? PG&E Exploring New Type of Clean Energy

23. SustainX CAES
Demonstration Project
 Small start-up company who raised $14.4million and
received a grant from US DoE of $5.39million,
highlighting the recognition for such projects to be
developed9.
 A 50kW plant has already been built and now
construction has begun on a 1MW, 4MWh plant10.
 Built using SustainX‟s patented Isothermal technology,
boasting the lack of fuel and secondary heat sources
involved.
 95% efficiency in both compression and expansion.
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[9] Source: Gigaom - SustainX Raises $14.4M for Air Energy Storage
[10] Source: US DoE – SistainX Inc - Isothermal Compressed Air Energy Storage

24. Advantages of CAES
 Reduces the costs in having no storage at all, thus reducing
wind curtailment.
 In 2011, wind farms were paid £25million to not produce
electricity due to extortionately high costs set by the wind farm
operators1.
 This money could be spent on installing CAES systems and so
the turbines would be able to store the energy produced, thus
eliminating costs for shut-down.
 Reduced emissions associated with the energy produced by
conventional methods.
 Storing energy that would otherwise be wasted results in a
reduction in emissions due to needless further production.
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[1] Source: Daily Mail – “Wind farms paid £25million NOT to produce electricity when it is blustery - and YOU pay”

25. Advantages of CAES
 Quick start-up time.
 0%-100% can be achieved in 10 minutes.
 50%-100% can be achieved in 15 seconds2.
 Vast areas in which the system could be implemented
 80% of US territory has geology suitable for CAES3.
 There just needs to be a proven technology with high
efficiency that could be applied to the possible sites.
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[2] Source: Arizona Research Institute for Solar Energy
[3] Source: Boise State University - “Overview of Compress Air Energy Storage”

26. Advantages of CAES
 Shift of cheap off-peak energy to expensive peak
energy.
 CAES uses excess energy at off-peak times to compress
air.
 It then generates electricity at times of peak demand,
when electricity prices can be 4 or 5 times as high.
 It is this difference in electricity price that generates income
for the cavern operators.
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27. Advantages of CAES
Using Salt Caverns
 Flexibility4
 Operate under very high pressure and so can very quickly
accept or deliver large amounts of air and hence can cope with
the intermittency of generation requirements caused by
renewable sources.
 Cycling
 Traditional gas caverns can traditionally only inject in the
summer and withdraw in the winter
 Base Gas
 Caverns must be primed with a base pressure of gas, which is
lower in salt caverns than it is with typical caverns, resulting in a
higher proportion of working gas from the cavern.
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[4] Source: EIA – “Salt caverns account for 23% of U.S. underground natural gas storage daily deliverability”

28. Conclusions
 As can be seen through the examples provided
throughout this presentation, compressed air energy
storage is an area of heavy research with projects
being set up by a number of companies.
 The original technology is already proven by the plants
at Huntorf and McIntosh, and now with advancements
in technology far greater efficiencies can be achieved.
 CAES systems provide an area of Engineering that
could become the focal-point for many years to come,
with investments richly rewarding.
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29. Thank you
20/08/2013 29Compressed Air Energy Storage Systems Worldwide