A battery energy storage system (BESS), battery storage power station, battery energy grid storage (BEGS) or battery grid storage is a type of energy storage technology that uses a group of batteries in the grid to store electrical energy. Battery storage is the fastest responding dispatchable source of power on electric grids, and it is used to stabilise those grids, as battery storage can transition from standby to full power in under a second to deal with grid contingencies.
Battery energy storage systems are generally designed to deliver their full rated power for durations ranging from 1 to 4 hours, with emerging technologies extending this to longer durations to meet evolving grid demands.Blair, Nate, Chad Augustine, Wesley Cole, et al. 2022. Storage Futures Study: Key Learnings for the Coming Decades. Golden, CO: National Renewable Energy Laboratory. NREL/TP-7A40-81779. https://www.nrel.gov/docs/fy22osti/81779.pdf Battery storage can be used for short-term peak power demand and for ancillary services, such as providing operating reserve and frequency control to minimize the chance of power outages.
They are often installed at, or close to, other active or disused power stations and may share the same grid connection to reduce costs. Since battery storage plants require no deliveries of fuel, are compact compared to generating stations and have no chimneys or large cooling systems, they can be rapidly installed and placed if necessary within urban areas, close to customer load, or even inside customer premises.
In 2025, the worldwide nonprofit Volta Foundation reported global BESS deployments grew by 104 GW / 257 GWh as costs fell 31% year on year. 40% of the cumulative BESS capacity was installed in 2025 alone.
In 2021, the power and capacity of the largest individual battery storage system was an order of magnitude less than that of the largest pumped-storage power plants, the most common form of grid energy storage. However, grid batteries do not have to be large — a high number of smaller ones (often as hybrid power) can be widely deployed across a grid for greater redundancy and large overall capacity.
As of 2019, battery power storage is typically cheaper than open cycle gas turbine power for use up to two hours, and there was around 365 GWh of battery storage deployed worldwide, growing rapidly. Levelized cost of storage (LCOS) has fallen rapidly. From 2014 to 2024, cost halving time was 4.1 years. The price was US$150 per MWh in 2020, and further reduced to US$117 by 2023.
Construction
Battery storage power plants and uninterruptible power supplies (UPS) are comparable in technology and function. However, battery storage power plants are larger.
For safety and security, the actual batteries are housed in their own structures, like warehouses or containers. As with a UPS, one concern is that electrochemical energy is stored or emitted in the form of direct current (DC), while electric power networks are usually operated with alternating current (AC). For this reason, additional inverters are needed to connect the battery storage power plants to the high voltage network. This kind of power electronics includes gate turn-off thyristor, commonly used in high-voltage direct current (HVDC) transmission.
Various accumulator systems may be used depending on the power-to-energy ratio, the expected lifetime and the costs. In the 1980s, lead-acid batteries were used for the first battery-storage power plants. During the next few decades, nickel–cadmium, nickel-hydride and sodium–sulfur batteries were increasingly used.Batteries for Large-Scale Stationary Electrical Energy Storage (PDF; 826 kB), The Electrochemical Society Interface, 2010, (engl.) Since 2010, utility-scale battery storage plants have increasingly relied on lithium-ion batteries, following declines in their cost and increases in their energy and power capabilities associated with the growth of the electric-vehicle industry. Batteries are becoming increasingly diverse, optimized for different aspects of customer requirements such as cost, safety, or durability.
A 4-hour flow vanadium redox battery at 175 MW / 700 MWh opened in 2024. Lead-acid batteries are still used in small budget applications.Große Batteriespeicher erobern die Stromnetze. pv-magazine.de. Retrieved 11 March 2016.
Safety Most of the BESS systems are composed of securely sealed battery packs, which are electronically monitored and replaced once their performance falls below a given threshold. Batteries suffer from cycle ageing, or deterioration caused by charge–discharge cycles. This deterioration is generally higher at high charging rates and higher depth of discharge. This aging causes a loss of performance (capacity or voltage decrease), overheating, and may eventually lead to critical failure (electrolyte leaks, fire, explosion). Sometimes battery storage power stations are built with flywheel storage power systems in order to conserve battery power.utilitydive.com, PG&E contracts for 75 MW of energy storage on its way to 580 MW of capacity. Dec. 4, 2015 Flywheels may handle rapid fluctuations better than older battery plants.zdf-video, ZDF - Planet E - Schwungradspeicher. 27 February 2013
BESS warranties typically include lifetime limits on energy throughput, expressed as number of charge–discharge cycles.
Lead-acid based batteries Lead-acid batteries, as a first-generation technology, are generally used in older BESS systems. One example is a battery commissioned in 1997 with a peak output of 1.6 MW and a continuous output of 1.0 MW. Compared to modern rechargeable batteries, lead-acid batteries have relatively low energy density. Despite this, they are able to supply high surge currents. However, non-sealed lead-acid batteries produce hydrogen and oxygen from the aqueous electrolyte when overcharged. The water must be replenished regularly to avoid damage to the battery, while the flammable gases must be vented to reduce the risk of explosion. This maintenance is not required for sealed technologies such as Li-ion batteries.
Lithium-based batteries
Lithium-ion batteries offer a long lifespan with minimal maintenance, high energy density, and low self-discharge, which makes them ideal for modern utility-scale BESS applications.
A drawback of some types of lithium-ion batteries is fire safety, mostly ones containing cobalt. The number of BESS incidents has remained around 10–20 per year (mostly within the first 2–3 years of age), despite the large increase in number and size of BESS. Thus failure rate has decreased. Failures occurred mostly in controls and balance of system, while 11% occurred in cells.
Examples of BESS fire accidents include individual modules in 23 battery farms in South Korea in 2017 to 2019, a Tesla Megapack in Geelong, the fire and subsequent explosion of a battery module in Arizona, and the cooling liquid short circuiting incidents and fire at the Moss Landing LG battery.
This resulted in more research in recent years for mitigation measures for fire safety.
By 2024, the lithium iron phosphate (LFP) battery has become another significant type for large storages due to the high availability of its components, longer lifetime and higher safety compared to nickel-based Li-ion chemistries. An LFP-based energy storage system that was installed in Paiyun Lodge on Mt. Jade (Yushan) (the highest alpine lodge in Taiwan) and operated since 2016 without a safety incident.
Sodium-based batteries Sodium-based batteries are another BESS technology. Compared to lithium-ion batteries, sodium-ion batteries have somewhat lower cost, better safety characteristics, and similar power delivery characteristics, but lower energy density. Its working principle and cell construction are similar, but use sodium instead of lithium as the intercalating ion. Sodium–sulfur batteries can operate safely at high temperatures. Notable sodium battery producers with high safety claims include (non-exclusive) Altris AB, SgNaPlus and Tiamat. The largest BESS utilizing sodium-ion technology began operating in Hubei province in 2024, with a capacity of 50 MW / 100 MWh. In 2026, CATL unveiled its modular TENER Sodium Energy Storage System, which offers 30 MWh storage capacity. It can deliver power for storage durations of 1, 2, 4, 6, and 8 hours, depending on the application. It operates at 65 decibels. It contracted with HyperStrong for a 60 gwh system.
Operating characteristics
Since they do not have any mechanical parts, battery storage power plants offer extremely short control times and start times, as little as 10 ms. They can therefore help dampen the fast oscillations that occur when electrical power networks are operated close to their maximum capacity or when grids suffer anomalies. These instabilities – fluctuations with periods of as much as 30 seconds – can produce peak swings of such amplitude that they can cause regional blackouts. Some of the parameters are voltage, frequency and phase. A properly sized battery storage power plant can efficiently counteract these oscillations; therefore, applications are found primarily in those regions where electrical power systems are operated at full capacity, leading to a risk of instability. However, some batteries have insufficient control systems, failing during moderate disruptions they should have tolerated. Batteries are also commonly used for peak shaving for periods of up to a few hours. A more recent use is strengthening transmission, as long power lines can be operated closer to their capacity when batteries handle the local difference between supply and demand.
Storage plants can also be used in combination with an intermittent renewable energy source in stand-alone power systems.
Largest grid batteries
Operating + 10 largest battery storage power plants by storage capacity Name Commissioning date Energy (MWh) Power (MW) Duration (hours) Type Country Location/coords RefsChagan Hada20264000Inner Mongolia, ChinaElena (Oasis de Atacama)202635004467LFPChileMaría Elena Edwards Sanborn2022-20243287Lithium-ionUnited StatesKhavda20262880IndiaGujaratNajran, Khamis Mushait, and Madaya20252600 each (7.8 GWh combined)6803.8LFPSaudi Arabiagrid-forming & black start 380kV gridCollie Synergy202524005004.8LFPAustraliaCollie, Western Australia Collie Neoen202522405604LFPAustraliaBisha 20005004Lithium-ionSaudi ArabiaAsirKashgar20005004LFPChinaXinjiang250 MW grid-forming invertersTongliao 20005004LFPChinaVistra Moss Landing Q2 – 2023 Q31800 (was 3000)450 (was 750)4Lithium-ionUnited StatesMoss Landing, CaliforniaEraring 120251770 (2800 in phase 2)460 (700 in phase 2)4AustraliaMelton/Melbourne Renewable Energy Hub 1600 6002.5Lithium-ionAustraliaMelton, VictoriaGemini 14163804Lithium-ionUnited StatesClark County, Nevada$1.2 Billion Gemini Solar+Storage Project To Use 100% CATL Batteries , CleanTechnica, Zachary Shahan, Octobter 18, 2022, accessed June 27, 2024Dengkou14106052.3LFP + vanadium flowChinaBayannurCrimson 14003504Lithium-ionUnited StatesRiverside County, California Desert Peak Energy Storage I 13003254Lithium-ionUnited StatesPalm Springs, California 2023 Q3 Clean Power Quarterly, American Clean Power Association, accessed June 27, 2024The Red Sea Project 1300Lithium-ionSaudi ArabiaTabuk provinceOff-the-grid/microgridVíctor Jara (Oasis de Atacama)13002006.5LFPChileTarapacá RegionEleven Mile 12003004United StatesPinal CountyPapago 12003004LFPUnited StatesPhoenix, Arizona
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