Energy Storage on the Grid: Informing Future Development

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Energy Storage on the Grid: Informing Future Development

Eric HittingerAdvisors: Jay Whitacre, Jay Apt

Department of Engineering and Public PolicyCarnegie 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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100 MW Natural

Gas TurbineCharge/ Maintain Energy

Curtailment

“Flat Power” Output (within deadband)

Wind Power vs. Time

Wind + Gas Power vs. Time

Wind + Gas + Battery Power vs. Time

Wind Generation

Sodium Sulfur (NaS)

Battery

A Co-located wind/natural gas turbine/energy storage system can deliver “baseload” power

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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

0% 100% 200% 300% 400% 500%$0

$10,000,000

$20,000,000

$30,000,000

$40,000,000

$50,000,000

$60,000,000

$70,000,000

$80,000,000

$90,000,000

Percent Change from Base Case Value

Cost

of P

rovi

ding

One

Yea

r of 1

00 M

W R

egul

ation

(M

illio

ns)

Module Capital Cost

Fixed Operating Cost

Module Energy Capacity

Lifetime

Property SlopeLifetime 0.23Fixed Oper. Cost 0.28Module Cap. Cost 0.73Module Energy Capacity 0

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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Questions!

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).

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In the Wind/Natural Gas/Storage systems, storage is used for intermittent sharp spikes

Wind

Natural Gas

Storage

100 MW Gas Turbine67 MW Wind Farm0.7 MWh Battery100 MW Target Power Output

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0% 4% 8%12%

16%20%

24%28%

32%36%

40%44%

48%52%

56%60%

64%68%

$0

$20

$40

$60

$80

$100

$120

$140

$160

$180

Average Cost of Electricity is relatively constant over a wide range of wind penetrations for the Wind/Gas/NaS Battery Systems

Battery Contribution

Wind Contribution

Gas Contribution

Delivered Wind Energy (percent of total delivered energy)

Aver

age

Cost

of E

lect

ricity

($/M

Wh)

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100 MW Natural

Gas TurbineCharge/ Maintain Energy

Curtailment

“Flat Power” Output (within deadband)

Wind Power vs. Time

Wind + Gas Power vs. Time

Wind + Gas + Battery Power vs. Time

Wind Generation

Sodium Sulfur (NaS)

Battery

The “load-following” application is very similar to the “baseload” application

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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 PropertiesFlywheel Energy Storage Parameters

Base-Case Value

Round-trip Efficiency 90%

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

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Supercapacitor PropertiesSupercapacitor 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