Data centers need a reliable electricity supply to keep servers, cooling systems, and other critical infrastructure running continuously. Growing AI workloads and rising power demand are putting additional pressure on grid capacity, while operators also face higher energy costs and increasing requirements for resilience.

Data center energy storage can help operators manage these challenges by storing electricity and making it available when needed. Depending on the system design, storage can support backup power, reduce peak demand, improve renewable energy use, and provide greater flexibility when grid supply is constrained.

Battery Energy Storage Systems (BESS) are one of the main solutions used for these applications, but the right technology depends on the data center’s power requirements, storage duration, operating profile, site constraints, and cost considerations.

This guide examines the main data center energy storage technologies, applications, benefits, and selection considerations to help operators understand where energy storage fits into modern data-center power infrastructure.

What Is Data Center Energy Storage?

Data center energy storage refers to systems that store electricity and deliver it when the facility needs additional power. These systems can connect with the utility grid, on-site renewable generation, UPS infrastructure, or other power systems to support the data center’s electrical requirements.

A data center can use energy storage for several different purposes. The system may provide backup energy during grid interruptions, help manage peak electricity demand, store renewable generation for later use, or provide additional flexibility when the grid cannot supply all of the facility’s required power.

Battery Energy Storage Systems (BESS) are one of the main technologies used for these applications. A BESS typically combines batteries with a power conversion system, controls, monitoring equipment, and other supporting infrastructure. The system’s power and energy capacity determine how much electricity it can deliver and how long it can support a load.

A UPS and BESS serve different roles in a data center’s power system. A UPS provides immediate power continuity to critical loads during a power interruption, while a BESS can store more energy and support applications such as backup power, peak shaving, load shifting, and renewable energy integration. Depending on the facility’s design, operators can use both systems together rather than treating BESS as a direct replacement for the UPS.

The right configuration depends on the data center’s power demand, required backup duration, load profile, grid connection, renewable generation, available space, and operating objectives.

Why Do Data Centers Need Energy Storage?

Data centers need energy storage because they must manage high and continuously changing electricity demand while maintaining reliable power. AI workloads can increase power density and create rapidly changing load requirements, placing additional pressure on electrical infrastructure. At the same time, grid capacity constraints can delay new data-center connections and make it difficult for operators to secure additional power as quickly as their facilities grow.

New Zealand is also seeing growing electricity demand from data centers. MBIE estimated that data centers represented about 90 MW of baseload electricity demand and has modelled further growth as new facilities are developed. This makes power availability, grid connections, and energy management increasingly relevant considerations for data-center operators in New Zealand.

Energy storage can address several of these challenges:

• Backup and resilience: Stored energy can provide additional power when the utility supply is interrupted or constrained.
• Peak demand management: Data centers can discharge stored energy during periods of high demand to reduce their reliance on grid power and manage demand-related costs.
• Renewable energy integration: Storage can capture excess electricity from on-site or contracted solar and wind generation and make it available when renewable output falls.
• Grid constraints: A BESS can provide additional power during periods when the grid connection cannot meet short-term increases in site demand.
• Energy cost management: Operators can charge storage when electricity costs are lower and discharge it during higher-cost periods, where the site’s tariff structure makes this strategy economical.
• Reduced generator dependence: Energy storage can reduce the need to rely on diesel generators for some operating scenarios, although it does not eliminate the need for an appropriate backup-power strategy.

Energy storage therefore gives data centers more flexibility in how they obtain, store, and use electricity. The value depends on the facility’s load profile, grid connection, tariff structure, reliability requirements, and energy-storage configuration.

What Energy Storage Technologies Can Data Centers Use?

Data centers can use several energy storage technologies, and each option suits different power, duration, space, and operating requirements. Battery Energy Storage Systems (BESS) are currently a key option for larger stationary applications, while UPS batteries and other long-duration technologies serve different roles.

Lithium-Ion Battery Energy Storage Systems

Lithium-ion batteries provide high energy density, fast response, and a relatively compact footprint. Data centers can use them in BESS installations for backup support, peak demand management, renewable energy integration, and other energy-management functions.

UPS Battery Systems

UPS battery systems provide short-duration power continuity for critical data-center loads when the utility supply fails or fluctuates. They typically work with the UPS rather than serving the same role as a larger BESS.

Flow Batteries

Flow batteries store energy in liquid electrolytes held in external tanks. Their design allows operators to scale energy capacity by increasing electrolyte volume, making them suitable for applications that require longer discharge durations and frequent cycling.

Long-Duration Energy Storage

Long-duration energy storage (LDES) covers technologies designed to deliver stored energy over extended periods. Depending on the application, LDES can help data centers manage prolonged grid constraints, integrate renewable generation, or provide longer-duration energy support.

Other Energy Storage Technologies

Data centers may also consider thermal energy storage and emerging or hybrid storage systems where their operating requirements justify them. These technologies can address specific applications, but their suitability depends on factors such as duration, response requirements, site conditions, integration needs, and project economics.

No single technology fits every data center. Operators should compare the storage duration, power requirements, available space, operating profile, reliability objectives, and lifecycle economics before selecting a system.

How Do Data Centers Use Energy Storage?

Data centers can use energy storage for more than emergency backup. Operators can deploy storage across several power-management applications, depending on the facility’s electrical infrastructure and operating requirements.

• Backup and resilience: Stored energy can support critical loads when the utility supply fails or becomes constrained. This can give operators additional time while another backup source starts or until grid power returns.
• Peak shaving: A BESS can discharge during periods of high facility demand, reducing the amount of power the data center draws from the grid. This can help manage demand charges where the applicable electricity tariff includes them.
• Load shifting: Operators can charge the storage system during lower-cost periods and discharge it during higher-cost periods when the site’s operating conditions make this economical.
• Renewable energy integration: Storage can capture excess electricity from on-site solar or other renewable energy sources and release it when generation falls or demand increases. 
• Grid support: A suitably configured BESS can provide services such as demand response or other grid-support functions where the local market and connection arrangements allow them.
• Managing power constraints: Storage can provide additional power during short periods when site demand exceeds what the available grid connection can comfortably supply.

These applications can overlap. For example, a data center could use the same BESS for peak shaving during normal operation and additional backup capacity during a grid outage. The appropriate configuration depends on the facility’s load profile, electrical architecture, tariff structure, reliability requirements, and storage duration.

What Are the Benefits of Energy Storage for Data Centers?

Energy storage can improve how data centers manage power during both normal operation and grid disruptions. The main benefits depend on how the operator configures and uses the system.

• Greater power resilience: Stored energy can provide additional support when grid power becomes unavailable or constrained, helping maintain critical operations.
• Better energy-cost management: Operators can use stored electricity during high-cost periods or reduce peak grid demand where the tariff structure makes these strategies economical.
• Reduced reliance on diesel generators: Energy storage can handle some power requirements that would otherwise require generators, potentially reducing fuel use and generator operating time.
• Improved renewable-energy utilization: Storage allows data centers to retain excess renewable electricity and use it when generation does not match demand.
• More flexibility with grid capacity: A BESS can provide additional power during short periods of high demand, which can help data centers manage constrained grid connections.
• Support for grid services: Where local market rules permit, appropriately configured storage can participate in demand response and other grid-support services. These applications overlap with grid-scale energy storage, particularly when large facilities interact with constrained electricity networks. 

The value of these benefits depends on the data center’s load profile, grid connection, electricity tariff, storage configuration, and reliability requirements. Operators should evaluate those factors together rather than assume that installing storage will deliver the same benefits at every facility.

What Should You Consider When Choosing Data Center Energy Storage?

Data center operators should size and select energy storage around the facility’s actual power requirements and operating profile. The right system depends on how the data center intends to use storage, not simply on the battery technology.

Key factors include:

• Power capacity: Determine how much power the system must deliver and which loads it needs to support.
• Storage duration: Define how long the system must supply energy during each application, whether for short power support, peak management, or extended backup.
• Load profile: Review the facility’s normal and peak electricity demand, including how AI and other high-density workloads affect power requirements.
• Critical loads: Identify which systems require continuous support and which loads the storage system can support selectively.
• UPS and electrical integration: Ensure the storage system works correctly with the existing UPS, power-conversion equipment, generators, switchgear, and control systems.
• Available space: Account for batteries, inverters, cooling, electrical equipment, and required safety clearances when planning the installation.
• Safety requirements: Evaluate battery chemistry, thermal management, fire protection, containment, monitoring, and applicable standards.
• Scalability: Consider whether the system can expand as the data center increases its power demand or adds new capacity.
• Efficiency and cycling: Compare round-trip efficiency and expected cycling requirements with the facility’s operating strategy.
• Lifecycle economics: Evaluate capital cost, operating and maintenance costs, degradation, replacement requirements, and expected service life rather than focusing only on the initial purchase price.

A proper evaluation should compare these factors against the data center’s reliability objectives, grid conditions, energy costs, site constraints, and future power requirements. This approach helps operators choose a storage configuration that supports the facility’s actual operating needs.

What Is the Future of Energy Storage for Data Centers?

Data center power requirements will continue to change as AI workloads, cloud computing, and high-density computing expand. At the same time, many operators face limits on grid capacity and longer timelines for new power connections. These conditions can increase the value of energy storage as part of a broader data-center power strategy.

AI data centers may place particularly high and variable demands on electrical infrastructure. Energy storage can help manage short periods of high demand and provide greater flexibility between the facility, on-site generation, and the grid.

Data centers are also likely to use hybrid power systems that combine storage with grid connections, renewable generation, UPS systems, generators, and energy-management controls. Instead of relying on one technology for every requirement, operators can assign different power resources to the services they perform best.

Longer-duration storage could also become more relevant as data centers seek to manage extended grid constraints and increase their use of renewable electricity. However, longer duration does not automatically make a storage system a better choice. Operators still need to match storage duration and technology to the facility’s actual load and operating requirements.

The future role of energy storage will therefore depend on more than battery performance. Grid availability, AI-driven power demand, renewable integration, electricity pricing, reliability requirements, and project economics will all influence how data centers deploy storage.

Conclusion

Data center energy storage can help operators manage growing power demand, improve resilience, and use electricity more flexibly. BESS, UPS batteries, flow batteries, and longer-duration storage technologies can serve different requirements, so the best option depends on the facility’s load profile, power capacity, storage duration, grid connection, and operating goals.

As data centers add higher-density and AI workloads, operators need to evaluate energy storage as part of the wider power infrastructure rather than as a standalone battery installation. A system designed around the facility’s actual requirements can provide useful support for reliability, energy management, renewable integration, and grid constraints.

Frequently Asked Questions

1. What is data center energy storage?

Data center energy storage stores electricity and makes it available when a facility needs additional power. Operators can use storage for backup support, peak demand management, renewable energy integration, and other power-management applications.

2. Why do data centers need battery energy storage?

Data centers can use battery energy storage to improve power resilience, manage peak demand, integrate renewable electricity, and provide additional flexibility when grid capacity is constrained. The appropriate use depends on the facility’s electrical requirements and operating profile.

3. What type of battery is best for a data center?

There is no single battery technology that suits every data center. Lithium-ion batteries offer high energy density and fast response, while flow batteries can suit applications that require longer-duration storage and frequent cycling. Operators should compare the technology against their power, duration, space, safety, and lifecycle requirements.

4. Can BESS replace a data center UPS?

A BESS and UPS serve different functions. A UPS provides immediate power continuity for critical loads, while a BESS can provide additional energy capacity and support applications such as peak shaving, load shifting, renewable integration, and extended power support. In some designs, the systems can work together.

5. How long can energy storage power a data center?

The duration depends on the system’s energy capacity and the load it supports. A system designed for short-duration power support may operate for minutes or hours, while long-duration systems can provide energy for much longer periods. Operators should determine the required duration from the specific application rather than selecting a fixed duration for every data center.