Navigating the safety landscape of Energy Storage Systems with Matt Paiss, Technical Advisor at the Pacific Northwest National Laboratory

Energy Storage Systems (ESS) are a technological advancement that embody a revolution in our approach to powering the world.

These systems promise increased efficiency for electrical grids, bolster renewable energy sources, and offer resilience during power interruptions or peak demands.

However, with such transformative potential come safety considerations.

The risks associated with ESS, such as thermal runaway, stranded energy, and deep-seated fires, necessitate a thorough understanding and effective mitigation strategies.

The safety perspective

Matthew Paiss is a Technical Advisor at the Pacific Northwest National Laboratory (PNNL), funded by the US Department of Energy.

Paiss brings to light vital aspects of Energy Storage System (ESS) safety.

His expertise, especially in the realm of battery materials and systems, is crucial in understanding the intricacies of energy storage technologies.

Discussing the safety implications of these systems, Paiss points out the inherent risks associated with energy-dense technologies like lithium-ion batteries.

He notes that lithium-ion, while being the predominant technology in ESS due to its advanced scaling and cost-effectiveness, can pose risks if it fails.

“Lithium is very advanced in its scaling; it’s fairly inexpensive.

“But if there is a failure, a pretty energetic release is possible,” says Paiss.

It is particularly relevant in the context of consumer products, where lower manufacturing standards could lead to more frequent and hazardous battery failures​​.

Elaborating on the safety challenges, Paiss addresses the various facets of ESS safety that need attention.

He acknowledges that newer chemistries and technologies may emerge with better safety profiles, but for the current market, lithium-ion is the primary option.

This reality brings with it concerns about installations, especially in indoor environments or close to areas frequently occupied by people.

The proximity of ESS to living and working spaces amplifies the risks associated with potential failures.

Thermal runaway and stranded energy

One of the most critical safety issues in ESS is thermal runaway, a process where excessive heat in a cell can lead to a release of energy.

Paiss explains: “If the heating continues, then the plastic separator between the anode and cathode can melt, creating a direct short circuit, and then all of the energy in the cell is rapidly released in the form of flammable gas and potentially jet flames.”

This phenomenon is challenging to predict and can result from internal defects or electrical abuse like overcharging.

Stranded energy, another significant safety concern, refers to the residual energy in a damaged battery.

As Paiss explains: “Batteries always have energy in them, especially lithium-ion.

“They are not designed to be discharged to zero volts.”

This lingering energy poses risks during and after fire incidents, making it a crucial factor for emergency responders to be aware of.

Managing flammable and toxic gases

In ESS incidents, managing flammable and toxic gases is crucial.

Paiss emphasises the explosive potential of smoke from lithium-ion batteries: “Firefighters need to understand that any smoke coming from a lithium-ion battery is fuel.

“It’s typically a much more explosive mixture than smoke from common combustibles.”

This necessitates critical ventilation strategies during fires.

Moreover, Paiss highlights the toxic nature of emissions, such as hydrogen fluoride and heavy metals, from burning batteries.

He underscores the complexity of these emissions, calling them a “soup of different chemicals,” which could pose significant health risks and require specific protective measures for emergency responders.

Addressing deep-seated fires

On the challenges of deep-seated fires in ESS, Paiss questions the efficacy of certain fire suppression agents.

He notes that many agents, while effective in suppressing visible flames, fail to cool cells undergoing thermal runaway.

“What we typically find is most of the non-water agents are effective at suppressing visible flame.

“But what they’re not able to do is to cool the cells undergoing thermal runaway,” he explains.

This can trade off the fire risks for a deflagration risk where gases are still being produced.

This highlights the limitations of current fire suppression technologies in effectively addressing ESS fires.

Paiss also mentions the use of water, acknowledging its cooling benefits but also its conductive risks, suggesting a shift towards defensive strategies in certain situations​​.

Manufacturers that market agents must show that the agents are effective in finished ESS products in standardized testing such as UL 9540A, not simply a YouTube video of a few cells on a benchtop.

Preventing battery failures

Preventing battery failures in ESS involves a comprehensive approach, says Paiss.

He advocates for a systems approach, stressing the importance of component quality and integration, including the battery management system (BMS).

“The quality of all of the components and their integration is critical in maintaining a safe system,” Paiss asserts.

He also highlights the BMS’s role in maintaining cell balance and monitoring temperatures.

Paiss’s emphasis on the BMS underscores its importance in balancing voltages of all cells and preventing overcharging and ensuring the overall safety of ESS, demonstrating the need for meticulous monitoring and management to mitigate risks​​.

Implications for emergency services

Paiss highlights the growing need for emergency services to adapt to the challenges posed by Energy Storage Systems, emphasising that fire departments and emergency responders should be well-informed about the locations of large batteries, including those in residential settings.

Paiss advises, “For emergency response, they should understand where large batteries are located.

“On the residential side if we see solar array on the roof, that should be a red flag.”

Indicators such as solar arrays on roofs could signal the presence of a battery system.

Paiss also stresses the importance of pre-planning and recognising that in incidents involving battery failures, especially in the case of EV fires, the focus should be on life safety rather than saving the equipment: “The insurance company does not want firefighters taking any risks to try and save these systems.

“There’s rarely anything to save there – life safety is much more important”​​.

Paiss underscores the complex safety landscape surrounding Energy Storage Systems.

While ESS offers tremendous benefits in terms of energy efficiency and support for renewable sources, the associated risks cannot be overlooked.

Manufacturers should build to the highest safety codes & standards available, not the minimum local requirements.

Effective management of these systems requires a comprehensive understanding of the potential hazards, robust safety protocols, and well-informed emergency response strategies.

As we continue to integrate ESS into our energy infrastructure, prioritising their safety is not just prudent; it’s imperative for a sustainable and secure energy future.

This article was originally published in the December2023 issue of International Fire & Safety Journal. To read your FREE digital copy, click here.