CAES2™ 2nd Generation Compressed Air Energy Storage Technology

Presented at SmartEnergy CanadaToronto, February 15, 2011

Advanced Cycle Design to Optimize Renewables Integration and Enhance Grid Operation

Pat ConroyV.P.—Business Developmentpconroy@CAESpower.com

Bob KraftPresident & CEObkraft@CAESpower.com

CAES Basics• How CAES works:

– Off-peak electricity is used to compress and store air in a sealed underground reservoir or, for small units, an above-ground piping system.

– When electricity is needed, that air is expanded through a turbine driving a generator and returning the energy to the electrical system.

• The power rating of the system (MW) is determined by the size of the turbine-generator. The energy rating (MWh) is determined by the size of the storage reservoir. These are independent variables

• Only two commercial-scale CAES projects built to-date. – Huntdorf, Germany, 290MW (1978)—black start for nuclear unit– McIntosh, Alabama, 110MW (1991)—balance base-load coal plant

• Current interest in new CAES projects arises from a need to stabilize grid operation in the presence of large amounts of intermittent renewable generation & maximize value of renewable energy sources

CAES in the U.S.

Alabama Electric Coop. (now PowerSouth) CAES1 plant. COD 1991

• Only U.S. CAES plant … Only CAES plant anywhere in regular, continuous operation

• Developed as a load management plant with very specific objectives• Store off-peak energy for use during peak periods• Allow local coal-fired plants to continue efficient nighttime operation

• Challenging, but very successful project

ES&P’s History & Technology• ES&P is a joint venture of PSEG Global and Michael Nakhamkin—an

inventor of several CAES concepts• ES&P’s predecessor company—ESPC—was owner’s engineer for

McIntosh CAES Plant. Responsible for:– Design specification, technical supervision, commissioning management– Under EPRI contract, ESPC monitored plant operation for 3 years and

performed a lessons learned study• ES&P retains staff experience gained during CAES1 project• CAES2 was developed specifically to mitigate original design

limitations and optimize CAES for today’s market– Increased flexibility and operability– Elimination of “one-off” specialized components– Reduced capital and O&M costs– Fast starts & transitions between operating modes– Modularity—unit sizes from 10 to 500MW

CAES2 Cycle—compression mode

• Motor-driven compressors use off-peak electricity to compress and store ambient air in a reservoir. (Underground for plants larger than ~60MWh)

• Multiple independently driven compressors enable partial-power compression greatly reducing minimum compression power requirements to more easily match available off-peak energy & enabling fast starts & mode changes

CAES2 Cycle—generation mode• Compressed air from the storage reservoir is heated in SC GT exhaust recuperator and run through turbo-expanders—which provide 2/3 of total plant power. Remainder is generated by the gas turbine.• Cold expander exhaust air is used to chill inlet of GT – or to provide cogen energy, improving cycle efficiency.

• Compressors and expanders are all separately shafted providing high redundancy.• Expanders respond very rapidly and can provide ancillary services such as regulation and ramping

Cycle Comparison

FuelAftercooler

Compressors (50 MW)

LP HP

Expanders (110 MW)

HP IP-2 IP-1 LP LP HP

Intercoolers

SSS Clutches

Underground Storage Cavern: A Solution Mined Salt

Motor/Generator

Recuperator

Heat Rate-4100 Btu/kWhEnergy Ratio 0.81 kWh in/out

Exhaust Stack

Salt Cavern Air Storage:Depth 1500 ft

Volume = 22MCF

Pressure = 650 psi

CAES1

Storage

CAES1

CAES2

• Single-train limits operational flexibility• Slow transitions between modes• 9 major components in one train

• Unique high pressure in-line burner design:• Burner designs not scalable limiting:

• Reservoir pressure operating range• Unit module size flexibility

• Unique LP expander design using cooled nozzles = high cost

• 100% off-the-shelf, skid-mounted, industry proven components—available from multiple OEM’s• Proven GT OEM combustion system < 5 ppm NOx w/o an SCR—although one can be fitted if necessary• Any GT can be integrated—new or existing• Improved heat rate—virtually flat 100% to 50% load• Full power < 10 Minutes—from cold start• Full ‘nameplate’ power—even on very hot days• Can turndown to <25% of rated load & maintain NOx• Can supply virtually any ancillary service

Compressed Air

Motor-Driven Compressors

Gas Turbine

Storage

Air Recuperator

Fuel

Expander(s)

~

~

~

~

~

~

1200 psia

800 psia

StackExhaust

GT Air

Small Scale CAES

• Uses above-ground storage—no geological constraints

• Modular, skid-mounted• No incremental fuel burn or emissions• “Bolt-on” retrofit to any SC gas turbine.• Scalable Power—10MW modules• Scalable Energy—2 hour increments• Perfect for load center siting• Capable of ancillary services

10MW Bolt-on CAES2 Unit

Fuel inputUnchanged

Ambient Air input unchanged

GT Emissions Unchanged

GT MW Output Unchanged

NEW

10

MW

CA

SE S

kid

Mod

ule

Exist

ing

GT

New 6” Air pipes

New Air-to-Air Heat Exchanger inside Existing GT exhaust

Cold air Output at ambient pressure

10MW Expander Output during peak (for 4 hrs or 40

MWh)

Ambient Air Input

Electrical Energy input off peak (7MW for 6.5

hrs or 46MWh)

800F

750F80F

700F

Air Storage system~200,000 cubic feet @

1200 psi

Fast Starting Capability Options

Gas Turbine Ignition

Cold StartExpanders Synced, Pre-heat

Turning Gear, Pre-heat

0

10

20

30

40

50

60

70

80

90

0 2 4 6 8 10 12 14 16

Pow

er, %

of t

otal

pla

nt

Time, minutesBottoming Cycle Gas Turbine Total Plant

GT Synchronized

Bottoming Cycle Power, w/ optional

in-line burners

Gas Turbine Power

Total PlantPower

GT Ignition

Bottoming CyclePower w/ optional Duct Burners

3 Min. <7 Min.

Bottoming CyclePower, No aux burners

<10 Min.

Even without optional auxiliary burners 65% of total power is available within 10 minutes—cold start

Duct BurnersFire

Part-Load Operational Characteristics

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100

Pow

er G

ener

ated

, MW

Net Plant Load, %

ExampleGE7B CAES2 Plant Turn Down

Power Generated vs. Net Plant Load(Operating strategy optimized for energy sales)

Total Plant

Expander

GT

IC

100% GT

80%60%50% Inlet

Chilling

100% Exp

100% Plant

Fast Ramping Operational Strategy

0

20

40

60

80

100

120

140

160

180

30 40 50 60 70 80 90 100 110

Pow

er G

ener

ated

, MW

Net Plant Load, %

ExampleGE7B CAES2 Rapid Load Following

(Optimized for Ramping or Regulation Service)

Total Plant

Expander

GT100% Exp107 MW

20%

100% GT51 MW

46%

100% Plant158 MW

(Inlet chilling off)

Turbo expanders capable of full load swings <1 minute—repeatedly

0

50

100

150

200

250

300

350

400

450

500

0 1 2 3 4 5 6 7 8 9 10

Pow

er, M

W

Time, seconds

CAES2 Load Control During Plant Operation / Regulation

Total Plant Power

Time

Pow

er (M

W)

172 MW(100% Expander Power)

~72 MW(20% Expander Power)

< 1 Min

200

150

100

50

7B CAES2 Plant … 100 MW swing in < 1 min.

CAES2 Applications

• Renewables Integration– Shaping morning and afternoon ramps

• Broadening solar shoulders• Shifting energy towards system evening peak• Reducing severity of renewables fluctuations

– Increasing on-peak capacity factor—particularly for wind– Reduce transmission congestion– Provide firm capacity

• Balance combination of base load & wind units during off-peak without swinging base-load units

• Provide significantly faster regulation than GT’s• Peak to off-peak energy arbitrage

Summary• McIntosh CAES1 plant successfully supporting original AEC needs

• Significant restrictions due to application-specific design

• CAES2 offers significant operational flexibilities arising from new cycle design• Separately mounted off-the-shelf components—proven performance and durability• Highly variable compression rates & significantly reduced min. compression power

requirement• Integrates with any gas turbine providing flexible module size (15 to 400+MW / unit)• Significant turndown and peak power augmentation capabilities • Fast load swing/ramp speed • Low emissions (specific emissions rates likely below SCR criteria) • Lower comparative costs (Capital and O&M)• Highest CAES efficiency available• Designed with renewables integration duty in mind

• Successful CAES plant design and implementation relies on competent integration and optimization engineering• Plant thermodynamic modeling and expertise essential• ES&P holds the ‘know how’ experience with CAES

Energy Storage and Power can provide:– Advanced Technology for

• CAES2—both small and large scale• Humid Air Injection GT power augmentation

– Cycle design and optimization– Project management– EPC and EPCM packages in partnership with leading

engineer-constructors– Owner’ engineer services

1.908.393.0526pconroy@CAESpower.com