U.S. Grid Energy Storage Factsheet
Electrical Energy Storage (EES) refers to systems that store electricity in a form that can be converted back into electrical energy when needed.1 Batteries are one of the most common forms of electrical energy storage. The first battery—called Volta’s cell—was developed in 1800.2 The first U.S. large-scale energy storage facility was the Rocky River Pumped Storage plant in 1929.3 Research on energy storage has increased dramatically2, especially after the first oil crisis in the 1970s4, and has resulted in advancements in cost and performance of batteries5. Energy storage can have a substantial impact on the current and future sustainable energy grid.6
- EES systems are characterized by rated power in W and energy storage capacity in Wh.7 In 2023, the rated power of U.S. EES was 38.6 GW8 and of global EES was 178 GW9.
- In 2021, 1,595 energy storage projects were operational globally, with 125 projects in construction. 51% of operational projects are located in the U.S.10 California leads the U.S. in power capacity with 11.7 GW, followed by Texas.8
- Levelized cost of storage (LCOS) is the price of an output kWh inclusive of taxes, financing cost, and operations and maintenance.11
Top Ten States, EES Power Capacity (GW)8
The Range of LCOS by Technology(¢/kWh)12
Deployed Technologies
Key EES technologies include Pumped Hydroelectric Storage (PHS), Compressed Air Energy Storage (CAES), Advanced Battery Energy Storage (ABES), Flywheel Energy Storage (FES), Thermal Energy Storage (TES), and Hydrogen Energy Storage (HES).16 PHS and CAES are large-scale technologies capable of discharge times of tens of hours and power capacities up to 1 GW, but are geographically limited.17 ABES and FES have lower power and shorter discharge times (from seconds to 6 hours), and are often not limited by geography.17
Maturity of Energy Storage Technologies13
Characteristics of Energy Storage Technologies14, 15
Pumped Hydroelectric Storage (PHS)
- PHS systems pump water from a low to high reservoir, and release it through a turbine using gravity to convert potential energy to electricity when needed17,18, with long lifetimes (50-60 years)17 and operational efficiencies of 70-85%18.
- PHS provides more than 90% of EES capacity in the world19, and 96% in the U.S20. In 2022, PHS provided 70% of utility-scale EES power capacity in the U.S, a drop from 93% in 2019 due to growth in battery installations.20
Compressed Air Energy Storage (CAES)
- CAES systems compress air in an underground cavern. 21 The pressurized air is heated and expanded in a natural gas combustion turbine, driving a generator.22 As of 2023, the U.S. only had one CAES plant operating, a 110 MW plant in AL.8
- Existing CAES plants separate compression and combustion processes.22 This method can generate 3 times the output of each unit of natural gas input, reducing CO₂ emissions by 40-60%, and enabling plant efficiencies of 42-55%.22
Advanced Battery Energy Storage (ABES)
- ABES stores electricity as chemical energy.23 Batteries contain two electrodes (anode and cathode) and an electrolyte separating the electrodes. The electrolyte enables the flow of ions between the electrodes and external wires allow for electrical current to flow.23
- The U.S. has 575 operational battery energy storage projects8, using lead-acid, lithium-ion, nickel-based, sodium-based, and flow batteries10. These projects totaled 15.9 GW of rated power in 20238, and have round-trip efficiencies between 60-95%24.
Flywheel Energy Storage (FES)
- FES systems store kinetic energy by spinning a rotor in a low-friction enclosure, and are used mainly for grid management rather than long-term energy storage.22 The rotor changes speed when moving energy to or from the grid.17
- In 2023, FES systems accounted for 47 MW of rated power in the U.S.8, and have efficiencies between 85-87%24.
- FESS are best used for high power/low energy applications. There are two categories of FES: low-speed and high-speed. These systems rotate at up to 10,000 and 100,000 revolutions per minute (RPM), respectively.17
U.S. Energy Storage Projects by Technology, 20238
Applications
EES systems have many applications, including energy arbitrage, generation capacity deferral, ancillary services, ramping, transmission and distribution capacity deferral, and end-user applications (e.g., managing energy costs, power quality and service reliability, and renewable curtailment).26
EES can operate at partial output levels with low losses and can respond quickly to changes in demand.27 Storing energy in off-peak hours and using that energy during peak hours saves money and prolongs the lifetime of energy infrastructure.25
Round-trip efficiency, annual degradation, and generator heat rate have a moderate to strong influence on the environmental performance of grid connected energy storage.28
Energy storage will help with the adoption of intermittent energy, like solar and wind, by storing excess energy for times when these sources are unavailable.29
Daily Energy Storage and Load Leveling25
Solutions
Research & Development
- Storage technologies are becoming more efficient and economically viable. One study found that the economic value of energy storage in the U.S. is $228B over a 10 year period.27
- Lithium-ion batteries are one of the fastest-growing energy storage technologies30 due to their high energy density, high power, near 100% efficiency, and low self-discharge31. The U.S. has 1.1 Mt of lithium reserves, 4% of global reserves.32
- A zero-carbon future by 2050 would require 930GW storage capacity in the U.S33, and the grid may need 225-460 GW of long duration energy storage (LDES) capacity34. Hydrogen, CAES, and PHS are the most viable technologies for LDES.35
- When designing EES, it is important to ensure system deployment results in a net reduction in environmental impacts.36
Policy & Standardization
- 11 states have statewide energy storage deployment targets.37 For instance, Michigan targeted 2.5 GW by 2030.38
- The U.S. DOE disbursed $185M of American Recovery and Reinvestment Act funding to support 16 large-scale energy storage projects with a combined capacity of over 0.53 GW.39
- Wholesale electricity markets are required by the U.S. Federal Energy Regulatory Commission (Order No.841) to establish participation models that recognize energy storage’s physical and operational characteristics.40
- DOE’s Long Duration Storage Shot sets an LCOS target of $0.05/kWh by 2030, a 90% reduction from 2020 costs.41
- The 2022 Inflation Reduction Act provides a 30% Investment Tax Credit for energy storage technologies through 2032.42
Center for Sustainable Systems, University of Michigan. 2024. "U.S. Energy Storage Factsheet." Pub. No. CSS15-17.
References
1. Chen, H., et al. (2009) "Progress in Electrical Energy Storage System: A Critical Review." Progress in Natural Science, 19:291–312. http://www.sciencedirect.com/science/article/pii/S100200710800381X
2. Whittingham, S. (2012) History, Evolution, and Future Status of Energy Storage. Proceedings of the Institute of Electrical and Electronics Engineers (IEEE). https://ieeexplore.ieee.org/document/6184265
3. National Hydropower Association (NHA) (2012) Challenges and Opportunities For New Pumped Storage Development. http://www.hydro.org/wp-content/uploads/2014/01/NHA_PumpedStorage_071212b12.pdf
4. Sandia National Laboratory (SNL) (2021) “Energy Storage Systems (ESS) History.” https://www.sandia.gov/ess/ess/about-the-energy-storage-systems-program/history
5. National Renewable Energy Laboratory (NREL) (2018) 2018 U.S. Utility-Scale Photovoltaics-Plus-Energy Storage System Costs Benchmark. https://www.nrel.gov/docs/fy19osti/71714.pdf
6. NREL (2021) "Grid-Scale U.S. Storage Capacity Could Grow Five-Fold by 2050." https://www.nrel.gov/news/program/2021/grid-scale-storage-us-storage-capacity-could-grow-five-fold-by-2050.html
7. NREL (2016) "Batteries 101 Series: How to Talk About Batteries and Power-To-Energy Ratios." https://www.nrel.gov/state-local-tribal/blog/posts/batteries-101-series-how-to-talk-about-batteries-and-power-to-energy-ratios.html#:~:text=The%20more%20accurate%20term%20is%20the%20power%20rating,or%20absorb%20over%20the%20course%20of%20an%20hour.
8. U.S. Energy Information Administration (EIA) (2024) Form EIA-860. https://www.eia.gov/electricity/data/eia860/
9. U.S. DOE (2023) “Global Energy Storage Database Projects.” https://gesdb.sandia.gov/?
10. U.S. DOE (2021) “Global Energy Storage Database Projects.” https://www.sandia.gov/ess-ssl/global-energy-storage-database-home/
11. U.S. DOE (2022) 2022 Grid Energy Storage Technology Cost and Performance Assessment. https://www.energy.gov/sites/default/files/2022-09/2022%20Grid%20Energy%20Storage%20Technology%20Cost%20and%20Performance%20Assessment.pdf
12. PNNL (2024) Energy Storage Cost and Performance Database v2024. https://www.pnnl.gov/download-reports
13. World Energy Council (2020) Five Steps To Energy Storage. https://www.worldenergy.org/publications/entry/innovation-insights-brief-five-steps-to-energy-storage
14. U.S. DOE (2016) DOE/EPRI Electricity Storage Handbook in Collaboration with NRECA. https://www.osti.gov/servlets/purl/1431469
15. Rae, C., Kerr, S., & Maroto-Valer, M. M. (2020). Upscaling smart local energy systems: A review of technical barriers. https://www.sciencedirect.com/science/article/pii/S1364032120303117
16. U.S. DOE (2019) Solving Challenges in Energy Storage. https://www.energy.gov/sites/default/files/2019/07/f64/2018-OTT-Energy-Storage-Spotlight.pdf
17. U.S. DOE (2013) Grid Energy Storage. http://energy.gov/oe/downloads/grid-energy-storage-december-2013
18. Gür, T. M. (2018). "Review of electrical energy storage technologies, materials and systems: challenges and prospects for large-scale grid storage." Energy & Environmental Science, 11(10), 2696–2767. https://pubs.rsc.org/en/content/articlepdf/2018/ee/c8ee01419a
19. IHA (2024) 2024 World Hydropower Outlook. https://www.hydropower.org/publications/2024-world-hydropower-outlook
20. U.S. DOE (2023) U.S. Hydropower Market Report. https://www.energy.gov/sites/default/files/2023-09/U.S.%20Hydropower%20Market%20Report%202023%20Edition.pdf
21. U.S. Environmental Protection Agency (2018) Energy and the Environment - Electricity Storage. https://www.epa.gov/energy/electricity-storage
22. The American Clean Power Association (ACP) (2023) “Mechanical Energy Storage.” https://cleanpower.org/facts/clean-energy-storage/mechanical-electricity-storage/
23. U.S. DOE (2021) "DOE Explains - Batteries." https://www.energy.gov/science/doe-explainsbatteries
24. State Utility Forecasting Group (2013) Utility Scale Energy Storage Systems. https://www.purdue.edu/discoverypark/sufg/docs/publications/SUFG%20Energy%20Storage%20Report.pdf
25. Sabihuddin, S., et al. (2015) A Numerical and Graphical Review of Energy Storage Technologies. http://www.mdpi.com/1996-1073/8/1/172/htm
26. Sioshansi, R., et al. (2012) Market and Policy Barriers to Deployment of Energy Storage. https://pdfs.semanticscholar.org/a188/e9578e0d2319257cae3db2f1e0c88475348a.pdf
27. SNL (2010) Energy Storage for the Electricity Grid. https://www.energy.gov/sites/prod/files/2016/10/f33/sandia_energy_storage_report_sand2010-0815_Feb_2010.pdf
28. Arbabzadeh, M., et al. (2017) “Parameters driving environmental performance of energy storage systems across grid applications.” Journal of Energy Storage 12: 11–28. http://css.umich.edu/publication/parameters-driving-environmental-performance-energy-storage-systems-across-grid
29. NREL (2010) The Role of Energy Storage with Renewable Electricity Generation. http://www.nrel.gov/docs/fy10osti/47187.pdf
30. U.S. DOE (2011) Energy Storage Activities in the United States Electricity Grid. http://energy.gov/oe/downloads/energy-storage-activities-united-states-electricity-grid-may-2011
31. U.S. DOE (2012) Lithium-Ion Batteries for Stationary Energy Storage. https://www.energy.gov/sites/default/files/Li-ion.pdf
32. U.S. Geological Survey (2024) Mineral Commodity Summaries 2024. https://www.usgs.gov/publications/mineral-commodity-summaries-2024
33. NREL (2022) Storage Futures Study, Grid Operational Impacts of Widespread Storage Deployment. https://www.nrel.gov/docs/fy22osti/80688.pdf
34. U.S. DOE (2024) The pathway to long duration energy storage commercial liftoff. https://liftoff.energy.gov/long-duration-energy-storage/
35. NREL (2020) "Declining Renewable Costs Drive Focus on Energy Storage." https://www.nrel.gov/news/features/2020/declining-renewable-costs-drive-focus-on-energy-storage.html
36. Arbabzadeh, M., et al. (2016) Twelve Principles for Green Energy Storage in Grid Applications. https://pubs.acs.org/doi/abs/10.1021/acs.est.5b03867
37. DSIRE (2023) Summary Maps: Energy Storage Target. https://ncsolarcen-prod.s3.amazonaws.com/wp-content/uploads/2023/12/DSIRE_Storage_Targets_Nov2023.pdf
38. MPSC (2024) 2023 Energy Legislation. https://www.michigan.gov/mpsc/commission/workgroups/2023-energy-legislation
39. U.S. DOE (2014) Storage Plan Assessment Recommendations for the U.S. DOE. http://energy.gov/oe/downloads/2014-storage-plan-assessment-recommendations-us-department-energy-september-2014
40. U.S. Federal Energy Regulatory Commission (2018) Order No. 841. Electric Storage Participation in Markets Operated by Regional Transmission Organizations and Independent System Operators. https://www.ferc.gov/sites/default/files/2020-12/Order-No-841.pdf
41. U.S. DOE (2022) Biden Administration Launches Bipartisan Infrastructure Law’s $505 Million Initiative to Boost Deployment and Cut Costs of Increase Long Duration Energy Storage. https://www.energy.gov/articles/biden-administration-launches-bipartisan-infrastructure-laws-505-million-initiative-boost
42. U.S. EPA (2023) “Summary of Inflation reduction Act Provisions Related to Renewable Energy". https://www.epa.gov/green-power-markets/summary-inflation-reduction-act-provisions-related-renewable-energy