Informing Future Development

Report
Energy Storage on the Grid:
Informing Future Development
Eric Hittinger
Advisors: Jay Whitacre, Jay Apt
Department of Engineering and Public Policy
Carnegie Mellon University
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This study examines four energy storage
technologies and four applications
• Energy Storage Technologies:
–
–
–
–
NaS Batteries
Li-Ion Batteries
Flywheels
Supercapacitors
• Applications:
–
–
–
–
Frequency regulation provided by energy storage
Peak shaving using energy storage
Wind Integration (Baseload)
Wind Integration (Load-following)
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A Co-located wind/natural gas turbine/energy
storage system can deliver “baseload” power
Wind Power vs. Time
Wind
Generation
Curtailment
Charge/
Maintain
Energy
100 MW
Natural
Gas Turbine
Sodium
Sulfur (NaS)
Battery
Wind + Gas Power vs. Time
Wind + Gas + Battery Power vs. Time
“Flat Power”
Output (within
deadband)
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Energy storage is used only to smooth
the sharpest wind fluctuations
Wind Farm
Output
Output After Battery
“Smoothing”
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Cost-of-service is conceptually like a
production function
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Sensitivity plot for “Regulation” application
using flywheels
Cost of Providing One Year of 100 MW Regulation
(Millions)
$90
$80
$70
$60
Property
Slope
Lifetime
Fixed Oper. Cost
Module Cap. Cost
Module Energy
Capacity
0.23
0.28
0.73
Module Capital Cost
0
$50
Lifetime
Fixed Operating Cost
$40
$30
$20
Module Energy Capacity
$10
$0
0%
100%
200%
300%
Percent Change from Base Case Value
400%
500%
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Sensitivity of NaS battery properties
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Sensitivity of flywheel properties
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Sensitivity of Li-Ion battery properties
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Sensitivity of supercapacitor properties
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Capital cost improvements are still valuable even
after current technology targets have been met
Existing Targets
• US DOE’s Energy Storage Program: $250/kWh
• American Electric Power: $500/kWh
• ARPA-E GRIDS Program: $100/kWh
Using $250/kWh:
Capital Cost
Reduction
Average Change in
Sensitivity to Capital Cost
Li-Ion Battery
50%
20%
NaS Battery
30%
12%
Flywheel
50%*
25%
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Research Conclusions
The relative importance of storage properties
depends on storage type and application…
…but certain properties, particularly capital cost,
are consistently more valuable to improve.
These results can help inform:
– Energy Storage Development
– Research Funding
– Energy Storage Technology Targets
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Support for this research has been provided by the EPA
STAR Fellowship, the National Energy Technology
Laboratory of the Department of Energy, and the
Electric Power Research Institute under grants to the
Carnegie Mellon Electricity Industry Center (CEIC).
Questions!
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In the Wind/Natural Gas/Storage systems,
storage is used for intermittent sharp spikes
100 MW Gas Turbine
67 MW Wind Farm
0.7 MWh Battery
100 MW Target Power Output
Wind
Natural Gas
Storage
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Average Cost of Electricity is relatively constant over a wide range of
wind penetrations for the Wind/Gas/NaS Battery Systems
$180
Battery Contribution
Average Cost of Electricity ($/MWh)
$160
Wind Contribution
$140
Gas Contribution
$120
$100
$80
$60
$40
$20
$0
0%
10%
20%
30%
40%
50%
60%
Delivered Wind Energy (percent of total delivered energy)
70%
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The “load-following” application is very similar
to the “baseload” application
Wind Power vs. Time
Wind
Generation
Curtailment
Charge/
Maintain
Energy
100 MW
Natural
Gas Turbine
Sodium
Sulfur (NaS)
Battery
Wind + Gas Power vs. Time
Wind + Gas + Battery Power vs. Time
“Flat Power”
Output (within
deadband)
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NaS Battery Properties
NaS Battery Parameter
Base-Case Value
Round-trip Efficiency
80%
Module Energy Capacity
0.36 MWh
Module Power Limit
0.25 MW
Module Maintenance (Heating) Power
2.2 kW
Module Capital Cost
$240K ($670K / MWh)
Module Fixed Operating Cost
$8K / module - year ($22K / MWh-year)
Length of Capital Investment
20 years
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Li-Ion Battery Properties
Li-ion Battery Parameter
Base-Case Value
Round-trip Efficiency
80%
Capital Cost of Batteries
$500K / MWh
Capital Cost of Power Electronics
$300K / MW
Fixed Operating Cost
$8K / MW - year
Length of Capital Investment
10 years
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Flywheel Properties
Flywheel Energy Storage
Parameters
Round-trip Efficiency
Base-Case Value
Module Energy Capacity
0.025 MWh
Module Power Limit
0.1 MW
Flywheel Friction Losses
3% of max power (3 kW)
Module Capital Cost
$200K
Fixed Operating Cost
$5K / module - year
Length of Capital Investment
20 years
90%
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Supercapacitor Properties
Supercapacitor Parameters
Base-Case Values
Round-trip Efficiency
70%
Capital Cost of Supercapacitors
$143M / MWh
Capital Cost of Power Electronics
$60K / MW
Fixed Operating Cost
$13K / MW - year
Length of Capital Investment
20 years
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