Contributed by Matt Ward, President, EticaAG
The global transition to renewable energy has fueled an unprecedented demand for battery energy storage systems (BESS). These systems are critical for integrating renewable energy sources into the grid, ensuring reliability and stability.
However, safety concerns, particularly the risk of fires caused by thermal runaway, pose significant challenges. High-profile incidents, such as the fire at the Moss Landing Energy Storage Facility, have underscored the limitations of current cooling and safety measures.
Immersion cooling, patented for BESS by EticaAG (a joint venture between Etica Battery and AGI), offers optimal thermal management and advanced fire suppression. By directly addressing the root causes of thermal runaway, the technology enhances safety, reliability, and performance compared to conventional methods. This article examines the technical aspects of immersion cooling and its effectiveness in mitigating risks for BESS installations.
understanding thermal runaway
Thermal runaway occurs when a battery cell generates heat faster than it can be dissipated, leading to a chain reaction of overheating and failure in adjacent cells. This phenomenon is typically initiated by external stressors such as physical damage, overcharging, or elevated temperatures, which cause internal chemical reactions within the battery to accelerate uncontrollably.
As the reactions progress, they generate heat, which increases the chemical activity, creating a self-sustaining feedback loop that can culminate in fire or explosion. The process poses a significant safety hazard and undermines the reliability and operational efficiency of energy storage systems.
limitations of current cooling and fire suppression methods
Air cooling relies on the circulation of air to dissipate heat. This method is often ineffective in densely packed systems where airflow is obstructed, leading to uneven temperature distribution and hotspots that can trigger thermal runaway.
Liquid cold plate cooling, which uses conduits of liquid to absorb and transport heat away from the cells, provides better thermal management but remains inherently reactive. It addresses heat only after it has been generated, offering no preventive measures against the onset of thermal runaway.
Fire suppression systems, while essential, operate solely as a response to fires that have already occurred, focusing on containment rather than prevention. These methods collectively highlight the need for more proactive and comprehensive solutions to manage thermal risks in BESS.
Battery Immersion Technology: New Technology for BESS Fire Safety
Immersion cooling involves submerging battery cells in a dielectric, non-flammable liquid. However, EticaAG’s patented cooling circulation system goes beyond simple submersion.
Here’s how it works:
- The coolant absorbs heat directly from the battery cells and flows to a reservoir where the heat is dissipated.
- The system uses pumps to circulate the liquid, preventing thermal gradients that can compromise performance.
- An integrated battery management system (BMS) works in real-time to circulate the coolant throughout the system as needed.
Even in the unlikely event of a pump failure, the inherent fire protection remains fully effective. Since the liquid itself is non-flammable and continuously surrounds the battery cells, it prevents fire propagation regardless of circulation. The system’s core safety function, isolating cells from oxygen and external ignition sources, remains intact at all times.
This liquid circulation serves as a direct heat transfer medium, efficiently dissipating heat while isolating cells from oxygen and potential ignition sources. By surrounding each battery cell with this specialized liquid, heat is transferred almost instantaneously from the source, preventing temperature spikes that can lead to thermal runaway.
This method also eliminates the need for active air circulation, making it a more efficient and compact solution for thermal management.
Key Benefits of Immersion Cooling: Fire Suppression & Thermal Management
Unlike traditional air or cold plate cooling methods, where heat dissipation can be uneven, immersion cooling submerges the battery cells directly in a dielectric liquid. This approach ensures uniform temperature distribution across all cells, preventing localized hotspots that could lead to thermal runaway.
As discussed above, one of the primary safety concerns in lithium-ion battery storage is thermal runaway. Immersion cooling mitigates this risk through two key mechanisms:
- Oxygen isolation: The dielectric liquid forms a physical barrier around each cell, preventing exposure to oxygen – a necessary element for combustion. In the event of a cell failure, this isolation minimizes the risk of ignition, unlike air-cooled or cold plate systems, where venting gases can feed a fire.
- Heat containment and dissipation: If a battery cell undergoes thermal runaway, the surrounding liquid rapidly absorbs and dissipates the excess heat. This heat dissipation prevents neighboring cells from reaching critical temperatures, effectively containing the failure to a single cell. In contrast, air-cooling or liquid cold plate methods rely on external cooling loops, which may not react quickly enough to prevent fire propagation.
Beyond fire suppression, immersion cooling also optimizes battery performance by maintaining a consistent and controlled temperature environment. Lithium-ion batteries degrade faster when exposed to high temperatures or temperature fluctuations. Immersion cooling reduces thermal stress by:
- Minimizing temperature swings: The liquid surrounding the entire cell helps keep the battery’s temperature stable, preventing materials inside from expanding and contracting too much, which can cause wear and tear over time.
- Reducing electrolyte decomposition: High temperatures speed up the breakdown of electrolytes inside the cells, which contributes to capacity fading over time. By maintaining an optimal temperature range, immersion cooling slows degradation and extends battery lifespan.
- Enhancing energy efficiency: Batteries operate more efficiently when kept within their ideal thermal window. Stable and optimal temperatures mean improved charge/discharge efficiency and reduced energy losses.
By addressing fire risks and thermal stability, immersion cooling enhances safety and extends the operational life of BESS deployments. This makes it an ideal solution for mission-critical applications such as data centers, grid-scale energy storage, and commercial and industrial backup power, where reliability is paramount.
Could Immersion Cooling Have Prevented the Moss Landing Fire?
The Moss Landing incident, one of the largest BESS fires in recent history, was attributed to thermal runaway triggered by overheating. The failure of cooling systems and fire suppression measures allowed the issue to escalate, causing extensive damage and system downtime.
Reports indicated that the conventional air and liquid cooling methods in place were unable to dissipate the excessive heat generated by the batteries, leading to cascading failures.
The lack of a robust containment mechanism further exacerbated the situation, as the fire spread quickly across adjacent cells. Additionally, the facility’s fire suppression system struggled to extinguish the flames, highlighting the limitations of reactive measures in addressing thermal runaway events.
Immersion cooling could have fundamentally altered the course of events at Moss Landing by addressing the root causes of the fire. With the ability to provide direct and consistent heat dissipation, immersion cooling would have maintained battery temperatures within safe operating limits, preventing the initial overheating that triggered thermal runaway.
By submerging cells in a non-flammable, dielectric liquid, any thermal failure would have been immediately contained, preventing heat from spreading to adjacent cells and halting the cascade of failures before it began.
Furthermore, the fire-retardant properties of the immersion cooling liquid would have eliminated any flame or fire from thermal runaway, even in the event of a cell failure. This proactive containment approach would have mitigated the scale of the incident, minimizing damage and ensuring system stability under high-load conditions.
The Path to Safer Energy Storage
Thermal runaway remains a critical challenge in the deployment of large-scale battery energy storage systems. Incidents like the Moss Landing fire highlight the limitations of conventional cooling and safety measures. Immersion cooling offers a transformative solution, addressing the root causes of thermal runaway and significantly enhancing fire safety.
To ensure the safe and reliable growth of renewable energy storage, the energy industry must embrace innovative technologies like immersion cooling. By prioritizing safety and long-term performance, we can build a more resilient and sustainable energy future.
About the Author
Matt Ward is the new president of EticaAG, on a mission to bring safe and dependable energy storage to the utility, C&I, and residential markets. His career began in the US Navy as a civilian nuclear engineer, where he supervised the maintenance of nuclear reactors on U.S. Navy submarines, destroyers, and aircraft carriers. From there, he moved into construction, and then into the oil and gas industry. Next, his career pivoted into a real estate development firm as part of the executive team handling development and operations.
After that, Ward founded Solmicrogrid to bring safe and reliable power to small businesses. Its first client and collaboration was with Chick-fil-A, a billion-dollar company. Morgan Stanley invested, and Ward became the CEO before making a successful exit.
Two principles have resonated throughout Ward’s career- the first is that problems can be challenging but are rarely unsolvable, and the second is that perseverance and patience are everything. These have helped him succeed in both his personal and professional life and Ward says he takes them into every business venture.
