The energy storage industry is undergoing a remarkable transformation. Over the next five years, energy storage capacity in the United States is expected to grow almost 500%. This growth is being driven by the proliferation of renewable energy, which has positioned grid-scale batteries as a vital component of our energy infrastructure – providing balance and resiliency to electricity grids.
However, fires at energy storage systems have cast a shadow over the industry’s otherwise rapid ascension. While fire in the energy storage industry is a complex challenge requiring an integrated response, it’s crucial that manufacturers focus on developing and installing hardware that can prevent fires from starting and spreading.
Hardware plays a crucial role in sealing batteries away from foreign materials that can start fires, maintaining standard operating temperatures and defending against electrical irregularities. To ensure safety, reliability and sustained growth, manufacturers in the energy storage industry must address weaknesses in their hardware armory. We must bring the whole industry up to standard – and then push even further.
Protecting the vital components
All manufacturers must ensure that their batteries are protected from liquids and solids that could penetrate their batteries. Condensation, dust and other foreign objects can trigger fires if the battery enclosure or module is not properly sealed. The Ingress Protection (IP) rating gauges a system's resistance to these foreign substances, acting as the first line of defense against potential ignition sources.
For the battery enclosure—the external protective housing that surrounds and contains the components of a battery system—the minimum IP rating required is IP 55, a relatively high level of sealing effectiveness. At this level on the IP scale, enclosures are protected from limited dust ingress and from low pressure water jets from any direction. There is no minimum IP rating for modules—the self-contained units of battery cells within the larger system—but leading manufacturers should aim for a rating that matches the enclosure. This ensures the modules remain sealed during maintenance activities or a failure in the sealing of the enclosure, reducing the risk of exposure to foreign materials.
By meticulously designing and implementing high IP-rated enclosures and modules, manufacturers can create a robust barrier that effectively seals crucial components away from the elements.
Cooling the system
However, not all batteries can be effectively sealed. By definition, air-cooled battery systems are more exposed to foreign objects entering the enclosure or module compared to liquid-cooled systems. Air-cooling involves using the surrounding air to dissipate heat generated by the energy storage system. Once dust or dirt gets inside an air-cooled system, it may be recirculated throughout the enclosure. Liquid-cooling, on the other hand, utilizes a circulation system to pass a liquid coolant through a cold plate or pipes within the battery system.
While any system is susceptible to foreign materials breaking through seals, any IP weaknesses in an air-cooled system will soon be found out. By comparison, liquid-cooled systems are more resistant. They would have to undergo a critical malfunction or external damage to allow any foreign objects to enter the battery.
However, choosing between air-cooling and liquid-cooling also has implications beyond sealing the battery effectively. Cooling systems are a fundamental element in maintaining safe operating temperatures within a battery. One of the main fire risks associated with lithium-ion batteries is thermal runaway – a chain reaction within the battery that can start from a short circuit, manufacturing defect, external heat, overcharging or physical damage. Once one cell goes into thermal runaway, it can produce enough heat to cause adjacent cells to do the same, leading to a cascading failure. Cooling systems are responsible for cooling and thermal management to prevent or mitigate thermal runaway.
But not all cooling systems are built equal. Based on observations made during the manufacturing process, temperatures inside air-cooled systems can be up to 10 degrees higher than liquid-cooled systems. While air-cooling is generally simpler to implement and requires fewer components, it may have limitations in its ability to efficiently cool large-scale systems with high heat generation. In general, liquid-cooling systems can provide more precise temperature control, enabling better thermal management and ensuring the battery operates within safe temperature limits.
Cooling systems must work hand-in-hand with dehumidification systems to combat moisture inside the enclosure. Moisture can introduce the risk of short circuits, battery overheat potential and efficiency loss resulting from busbar corrosion. Air-cooled systems are susceptible to condensation. They often turn on and off, making the surface colder and potentially causing condensation.
Manufacturers must install cutting-edge, proven cooling systems to control the internal temperature of the battery system.
Defending against surges
Another vital hardware component within grid-scale batteries is the surge protection mechanism, which protects against electrical irregularities that could potentially damage vital equipment like control systems, batteries and fire alarm equipment. These mechanisms prevent equipment from exceeding their voltage or current ratings, which may occur as a result of lightning strikes, high speed operation of switches, or breakers and fuses opening under load.
Surge protection equipment must be designed, installed and maintained correctly to withstand these kinds of irregularities and prevent damage to the battery cells that could cause them to fail.
As a baseline, manufacturers should follow NFPA, CSA and IEEE requirements for surge protection under UL9540 and work with surge protection vendors and experts to ensure the design meets these requirements.
Hardware is one part an integrated solution
Hardware is only one facet of an integrated fire risk mitigation strategy that all manufacturers should be continuously developing and implementing. Advanced software is equally important, used to monitor for potential risks, alert staff to issues and implement automatic responses.
Beyond technological solutions, the industry must invest in fire safety testing and adhere to rigorous industry standards. Adherence to standardized safety protocols ensures that grid-scale battery projects are designed to withstand the most demanding conditions, minimizing the risk of catastrophic events. Finally, meaningful engagement with regulatory bodies, emergency responders and local communities is crucial to facilitate information-sharing and the development of effective emergency response plans.
The final word
As the energy storage industry forges ahead to facilitate the global energy transition, the imperative to address fire risks cannot be understated. By prioritizing their energy storage systems’ IP rating, cooling systems, and surge protection mechanisms—within a broader, integrated fire safety strategy—manufacturers can ensure the reliability and safety of their projects. As a starting point, all manufacturers must be brought up to par on hardware. But they can’t stop there — they must go above and beyond the minimum requirements to eliminate energy storage fires and realize the industry’s full potential for growth.