Immersion cooling, submerging hardware in a dielectric fluid, has become a standard practice in high-performance computing environments to address rising thermal loads. It's effective, scalable, and supports energy efficiency in dense server configurations.

At the same time, battery energy storage systems (BESS) and uninterruptible power supplies (UPS) are increasingly deployed in data centers to ensure uptime and energy resilience. However, these systems introduce new thermal management and safety challenges that are often under-discussed.

This article explores how immersion cooling, already validated in IT infrastructure, is being technically adapted to enhance the safety and performance of lithium-ion battery energy storage systems.

Immersion cooling in IT: performance where it counts

In IT infrastructure, immersion cooling is used to manage high thermal loads from CPUs and GPUs. The approach typically involves either single-phase or two-phase systems. In single-phase immersion cooling, hardware is submerged in a non-conductive liquid that absorbs heat and is then circulated through a heat exchanger.

Key performance characteristics include:

  • High thermal transfer efficiency: Fluids used typically have thermal conductivities 10-20 times that of air.
  • Energy savings: Systems achieve Power Usage Effectiveness (PUE) ratios as low as 1.05.
  • Greater hardware density: Enables deployment of server racks exceeding 100 kW without throttling.

These capabilities directly address the limitations of air cooling in high-density applications. Similar thermal stress profiles found in battery storage systems suggest that this approach is adaptable beyond CPUs.

Why lithium-ion battery racks are a fire risk

Lithium-ion batteries used in BESS and UPS systems are thermally sensitive. Chemistries like NMC, LFP, and NCA offer high energy density but are susceptible to thermal runaway, a self-reinforcing failure mechanism that can lead to combustion.

Thermal runaway may begin at temperatures as low as 150°C and result in:

  • Rapid cell heating
  • Electrolyte breakdown and gas release
  • Propagation of failure to adjacent cells

Real-world incidents demonstrate that standard HVAC systems cannot contain these events. Examples include the 2022 SK Group data center fire in South Korea and the 2019 McMicken BESS explosion in Arizona, highlighting the need for proactive thermal containment strategies.

Thermal Runway EticaAG
– EticaAG

Immersion cooling for energy storage: a safer, smarter evolution

In energy storage, immersion cooling involves submerging battery cells in dielectric fluid with high flash points and chemical stability. The system works by drawing heat directly away from each cell while acting as a barrier to oxygen, which is necessary for combustion.

Applications beyond backup power

Modern BESS solutions serve more than backup roles. They improve power quality, enhance uptime, and reduce operational costs.

Power quality conditioning: The BESS stabilizes voltage during sags or spikes by injecting or absorbing power within milliseconds. It also regulates frequency in both grid-tied and islanded modes. Additionally, it filters harmonics and smooths transients, improving power quality and reducing strain on IT equipment.

Extended backup power (UPS companion): The system reacts instantly to outages and can support loads for hours. This bridges longer failures, reduces generator reliance, and cuts emissions. Part of the battery can be reserved for emergencies while the rest serves economic functions.

Peak shaving and load management: During high-demand periods, the BESS discharges to lower grid draw. This reduces demand charges and flattens load profiles. It can also defer infrastructure upgrades and enable energy arbitrage, charging off-peak and discharging during peak hours.

By combining these features, immersion-cooled BESS transforms from a passive backup tool into a dynamic asset that boosts reliability and efficiency.

Deployment considerations for data centers

Operators considering immersion-cooled BESS should evaluate the following factors:

  • System footprint: Modular designs are available that align with standard rack configurations.
  • Monitoring systems: Integration with battery management and facility monitoring platforms is essential.
  • Standards compliance: Systems should meet UL 9540, UL 1973, and NFPA 855 standards.
  • Maintenance: Fluids are stable over long periods and require infrequent replacement.

Financially, immersion cooling may entail higher initial costs, but calculations indicate an average return on investment in under eight years due to operational savings and extended equipment lifespan.

Bringing battery safety up to server standards

As data centers evolve, the technologies used to ensure performance and safety must evolve as well. Immersion cooling, already validated in server environments, presents a technically viable and safety-enhancing method for managing the thermal and fire risks associated with lithium-ion energy storage systems.

Adapting proven thermal management strategies from computing to energy systems offers a path forward for safer, more efficient infrastructure.

Facilities planning to expand BESS capacity or modernize thermal controls should consider immersion cooling as a serious option grounded in existing best practices and emerging safety standards.

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