How Wärtsilä uses AIMS to manage fire safety

by Featured NewsResearchSafety

Quantum3 test campaign and fire safety scope

Wärtsilä Corporation has reported the completion of three major fire safety and explosion tests for its Quantum3 battery energy storage system in a programme designed to show performance under worst-case conditions.

The company said the test campaign covered UL 9540A unit-level testing, Large Scale Fire Testing and proprietary Active Ignition Mitigation System (AIMS) testing.

According to Wärtsilä Corporation, the scenarios were designed to reflect severe fire and explosion conditions and to generate data for manufacturers, first responders, customers and regulators.

The company stated that the combined results confirm Quantum3’s ability to contain thermal runaway events, prevent fire spread between units and mitigate hazards linked to flammable gas build-up in order to protect surrounding communities.

CSA Group, which works in standards development and product testing, inspection and certification, took part in planning the tests and witnessed execution of all three phases as an independent verifier.

Dana Parmenter, Commercial Vice President, Industry, CSA Group, said: “CSA Group was pleased to support Wärtsilä’s fire safety testing program through close collaboration between our North American and Asian teams.

“The strong coordination between teams helped ensure the testing was carried out smoothly and effectively.”

UL 9540A outcomes and large-scale fire results

Wärtsilä Corporation stated that Quantum3 met all required performance criteria during UL 9540A testing, which examined behaviour if a battery cell were to enter thermal runaway.

The results showed that a thermal runaway event in a single cell did not spread to neighbouring modules or enclosures.

The company added that no external flaming occurred during these tests and that no explosion hazards were observed.

In separate Large Scale Fire Testing carried out under CSA/ANSI C800:25, a fire was ignited inside a Quantum3 unit and allowed to burn for more than 22 hours in controlled conditions.

Wärtsilä Corporation reported that the fire remained confined to the initiating unit and did not propagate to adjacent units, even without intervention or water-based fire suppression.

The company stated that these large-scale results support the containment outcomes seen in UL 9540A testing at unit level.

AIMS validation and broader fire safety performance

Wärtsilä Corporation also validated its Active Ignition Mitigation System (AIMS) technology as part of the programme.

According to the company, AIMS is designed to ignite flammable gases at an early stage of a thermal event so that uncontrolled deflagrations are avoided and enclosure integrity is maintained during extreme conditions.

The company described Quantum3 as the most advanced system within its Quantum battery energy storage portfolio and said it provides a fully integrated AC block solution with safety, cybersecurity, energy density and sustainability features.

Wärtsilä Corporation stated that Quantum3 incorporates enhanced fire safety measures, including advanced fire suppression and next-generation thermal management, which it says exceed current global regulatory requirements.

Mishaal SyedNaveed, Product Manager – Fire Protection at Wärtsilä Energy Storage, said: “These results reflect years of engineering innovation and safety-first design.

“By completing all three tests, Quantum3 has proven its best-in-class safety performance, giving our customers and the general public confidence that Wärtsilä systems are ready for the most demanding applications.”

The company added that it plans to continue working with first responders, customers and regulators so that fire safety in battery energy storage keeps pace with rapid deployment worldwide.

Fire safety implications for energy storage stakeholders

The test results for Quantum3 are relevant for equipment specifiers and fire engineering consultants involved in battery energy storage projects where containment of thermal runaway and management of flammable gases are key design considerations.

The combination of UL 9540A unit-level testing and Large Scale Fire Testing under CSA/ANSI C800:25 provides standards and certification bodies with a documented example of how one system performs under both cell-initiated and enclosure-wide fire conditions.

Risk assessors and system installers can draw on the demonstrated ability to limit fire spread between units and to avoid external flaming when evaluating project layouts and separation distances for energy storage installations.

Facility managers responsible for industrial, commercial and public-sector sites that host battery energy storage can use the reported fire suppression and thermal management features as part of their review of equipment options, where compliance with current global regulations is a core requirement.

First responders and emergency planners may use the data generated by Wärtsilä Corporation’s testing to inform incident response planning for locations that deploy Quantum3 or comparable systems designed around containment and gas management.

Regulators and authorities that oversee energy storage safety can reference the described test programme when considering future expectations for fire performance and third-party verification in new or updated guidance.

First sodium-ion battery storage systems deployed on U.S. grid

by Featured NewsFire SuppressionProductsSafety

Launch of sodium-ion battery storage systems in the United States

Peak Energy has reported the launch and shipment of its sodium-ion battery energy storage system to the U.S. electric grid.

This is the first grid-scale sodium-ion storage solution to be deployed in the United States, according to the developer.

The system features a patent-pending passive cooling design intended to reduce lifetime energy costs.

It also removes components identified by independent third-party reports as being involved in most battery storage system fires.

The launch forms part of a pilot programme with nine utility and independent power producer customers this summer.

Passive cooling and design features

Peak Energy stated that its sodium-ion phosphate pyrophosphate battery storage system eliminates all moving parts, including active cooling and ventilation components.

Removing these parts reduces the most common failure modes in battery storage systems.

The design is intended to increase reliability and reduce operating and maintenance costs.

Sodium-ion chemistry enables operation across a wide range of temperatures without auxiliary cooling systems.

This contrasts with lithium-ion technologies, which require active cooling and ventilation to preserve cell life and prevent fires.

Cost and performance claims

The grid storage system is cost-competitive with other industry products.

Its design provides lower operating and maintenance costs over its lifetime.

Passive cooling allows for reduced auxiliary power use and fewer components likely to fail.

Performance testing indicated operational cost savings of at least $1 million annually per gigawatt hour installed.

Testing also showed approximately 20% lifetime cost savings compared to lithium iron phosphate deployments and a 33% reduction in battery degradation over 20 years.

Policy and supply chain considerations

The launch comes as U.S. federal policies are increasing the focus on domestic energy supply chains.

Rising energy demand has made battery storage essential for grid resilience and cost reduction.

Sodium-ion technology offers supply chain advantages for the United States.

The country holds the largest reserves of soda ash, a mineral used to produce sodium-ion batteries.

The full raw material supply chain can be sourced domestically or from allied nations.

Statements from company leadership

Landon Mossburg, CEO and Co-Founder at Peak Energy, said: “We see energy storage not only as an economic imperative, but also as a national security priority.

“Time is of the essence if the U.S. wants to take ownership and maintain control of its energy future.”

“We are committed to onshoring the manufacturing of this critical industry, and this launch proves our ability to execute quickly on our vision to establish the U.S. as a global leader in battery manufacturing.”

Paul Durkee, VP of Engineering at Peak Energy, said: “This isn’t just another product launch – it’s a breakthrough in energy storage.

“We’ve taken a very stable chemistry and invested its benefits back into our passive cooling architecture.

“The system is dead-simple with no moving parts, no planned maintenance and negligible aux loads.

“It’s the lowest total-cost grid storage technology to be deployed anywhere in the world.

“I’m incredibly proud of the creativity and grit our team has shown in bringing our vision to life.”

Future deployment plans

The pilot project is an initial step in commercialising sodium-ion battery storage in the U.S.

Nearly 1GWh of future commercial contracts are under negotiation.

Over the next two years, several hundred megawatt hours of commercial-scale storage will be deployed to multiple independent power producer and hyperscaler partners.

Development is also underway for the first U.S. cell factory, scheduled to begin production in 2026.

This follows $55 million in Series A funding in 2024 and the company’s launch from stealth in 2023.

Relevance for fire and safety professionals

The removal of active cooling and ventilation systems in this design addresses components linked to many battery storage system fires, according to independent third-party reports.

For fire and safety professionals, this may change risk assessment protocols for grid-scale storage installations.

The adoption of sodium-ion chemistry in grid applications could influence emergency response planning, particularly in temperature extremes where lithium-ion systems require auxiliary systems.

Understanding the operational characteristics of passive-cooled systems will be important for developing training, maintenance, and inspection standards.

First sodium-ion battery storage systems deployed on U.S. grid: Summary

Peak Energy has launched its sodium-ion battery energy storage system in the United States.

This is the first grid-scale sodium-ion storage system to be deployed on the U.S. electric grid.

The design uses passive cooling and removes components linked to battery storage system fires.

The system can operate without active cooling or ventilation across a range of temperatures.

Testing indicated operational cost savings of at least $1 million annually per gigawatt hour installed.

Results also showed 20% lifetime cost savings versus lithium iron phosphate and reduced battery degradation.

Sodium-ion offers domestic supply chain advantages due to U.S. soda ash reserves.

The pilot project involves nine utilities and independent power producers.

Commercial contracts under negotiation total nearly 1GWh.

Production at the first U.S. cell factory is planned for 2026.

How CLOU’s battery system burned for 59 hours without spreading fire

by Featured NewsFire EngineeringResearchSafety

CLOU reports fire test for Aqua C2.5 battery system in North America

CLOU has announced the results of a 59-hour fire test on its Aqua C2.5 battery energy storage system, carried out at a CSA-accredited test site in April 2025.

According to CLOU, the test simulated a large-scale fire in a 20MWh deployment to assess thermal runaway containment and explosion prevention mechanisms.

The company said the evaluation was performed using four 5MWh containers configured side by side to mimic actual high-density energy storage layouts.

The ignition container burned for over 59 hours with temperatures exceeding 1300°C.

No fire suppression systems were triggered during the test, enabling analysis of how CLOU’s Active Ventilation & Explosion-Proof System prevented the spread of fire to adjacent units.

System withstood prolonged high temperatures without thermal propagation

CLOU stated that the test configuration placed the Aqua C2.5 containers in back-to-back and side-by-side arrangements.

The ignition unit, labelled Container A, was exposed to extreme conditions while the other three units were monitored for signs of thermal propagation.

The manufacturer said the internal temperature of Container A exceeded 1300°C and sustained combustion for 59 hours and 10 minutes.

It reported that adjacent containers did not experience thermal deformation or battery damage.

According to CLOU, this result demonstrated the ability of the ventilation system to direct flames vertically, preventing lateral heat spread.

Thermal sensors in the adjacent containers recorded no temperatures high enough to trigger runaway events.

Design features based on NFPA and CSA standards

CLOU said the safety system design is based on North American energy storage standards, including NFPA 69, NFPA 68, NFPA 855, and CSA/ANSI C800.

According to the company, explosion prevention is handled by active ventilation triggered at 10 percent of the lower explosive limit (LEL), reducing gas levels below 25 percent LEL.

It said the Aqua C2.5 is also equipped with pressure relief structures and fixed-angle louvers, which direct gas and flame discharge vertically during a blast.

This design is intended to prevent the ignition of adjacent containers, even in high-density deployment.

The test also aligned with CSA/ANSI C800 criteria, which call for full-scale validation of thermal runaway and containment effectiveness.

Multi-layered detection and suppression system

The company explained that the fire safety architecture begins with the battery management system monitoring real-time voltage and temperature.

It said the BMS triggers early-stage alarms and disconnects charge-discharge circuits to prevent thermal propagation.

If temperatures continue to rise, gas detectors activate forced ventilation to lower explosive gas levels.

At a secondary threshold, a water-based suppression system is deployed to cool overheated components and reduce reignition risk.

According to CLOU, this coordination between ventilation and suppression supports continuous removal of flammable gases during incidents.

Fire test included deflagration and explosion venting validation

CLOU reported that the fire test also evaluated the performance of structural venting under extreme conditions.

It said the five natural exhaust louvers served as flame outlets and pressure relief mechanisms.

According to the test data, flames were vented at a fixed upward angle, limiting the heat exposure to other units in the layout.

The louvers functioned independently of external power supply, activating through thermal pressure when necessary.

CLOU stated that the design ensures explosion prevention even during power loss scenarios.

The test confirmed the louvers’ effectiveness in avoiding flame spread during deflagration.

CLOU completes 59-hour fire test on Aqua C2.5 battery system: Summary

CLOU has published results from a 59-hour fire test on its Aqua C2.5 containerised energy storage system.

The test involved four 5MWh units in a 20MWh layout and was witnessed by CSA Group.

Container A was ignited and burned at over 1300°C for more than 59 hours.

No suppression systems were used during the test.

The fire did not spread to adjacent containers.

Temperatures in other units remained below thermal runaway thresholds.

Flames were vented upwards through fixed louvers to avoid cross-container ignition.

The ventilation system maintained flammable gas concentrations below explosive limits.

The safety system was designed in line with NFPA and CSA/ANSI C800 standards.

The system includes real-time thermal monitoring and automated ventilation and suppression triggers.

Louvers activated passively using thermal pressure in power loss conditions.

Explosion pressure was relieved by structural venting.

The fire test confirmed the system’s containment and venting performance.

Augwind unveils commercial AirBattery in Germany

by Featured NewsIndustrial

Israel-based Augwind to deploy energy storage system in Germany

CleanTechnica has reported that Israel’s Augwind Energy will construct the world’s first commercial-scale AirBattery energy storage system in Germany.

The project will use compressed air stored in underground salt caverns to provide electricity during periods of low renewable generation.

This type of long-duration energy storage is designed to complement intermittent energy sources like wind and solar.

The compressed air will be generated using surplus renewable energy from the grid.

Or Yogev, Founder and CEO of Augwind Energy, discussed the initiative with CleanTechnica in a recent interview.

The system will store energy for several months

The company explained that the AirBattery will be able to store compressed air for up to several months.

Yogev said: “We can store energy for up to several months – a game-changing capability for addressing Germany’s ‘Dunkelflaute’ periods when solar and wind output is low.

“Our system has unlimited duration potential, limited only by the volume of the cavern itself.

“This long-duration storage capability is exactly what Europe needs as renewable energy penetration exceeds 50%.”

The compressed air is stored in solution-mined salt caverns, which are naturally airtight due to their density and pressure.

Yogev said: “The salt in the deep underground is highly condensed and pressurised by the weight above it.

“It is so dense that it is completely airtight.

“This unique characteristic has led to the use of solution mined salt caverns for safely storing compressed natural gas for over half a century.”

Installation timeline and turbine generation capacity

The AirBattery system will require between 9–12 months for installation and an additional 3–6 months for commissioning once permitting is finalised.

The facility will include 3 or 4 turbines, capable of generating between 3–10 MW of electricity on average.

Yogev said: “The turbines will be similar to the highly efficient Voith Hydro turbine currently operating in our demonstration site.”

To improve power quality and responsiveness, the system will be integrated with lithium-ion batteries.

Yogev added: “We couple the system with short-duration lithium-ion batteries for ancillary services and to provide a high-quality power profile.”

While the startup speed is slower than lithium-ion, the integration allows rapid deployment when needed.

Commercial model and system costs

The total cost of the first module will depend on the specific cavern selected and is expected to range between €7 million and €15 million.

AirBattery’s projected cost per kilowatt-hour for multiweek storage is estimated at 10–15 USD.

Yogev said: “Our AirBattery technology offers exceptionally competitive economics at 10–15 USD per kWh for multiweek duration storage.

“This cost-effectiveness, combined with our minimal environmental footprint and use of locally sourced materials rather than critical minerals, makes AirBattery the clear choice for Germany’s energy transition needs.”

The system is designed to work with wind and solar electricity that would otherwise be curtailed due to grid oversupply.

Augwind intends for this approach to reduce reliance on imported energy sources.

Yogev explained: “We’re taking excess renewable electricity that would otherwise be wasted during periods of oversupply and storing it for when Germany needs it most.”

Deployment partners and market role

The company is currently finalising partnerships with various stakeholders including energy traders, utilities, cavern owners, and industrial customers.

Although the names of participating partners have not yet been confirmed, Augwind says that demand from the German energy market has been strong.

Yogev said: “Our goal is to become Europe’s preferred partner for multiweek storage solutions, and this German launch will demonstrate that long-term energy storage is not only technically feasible but economically sound.”

The project’s final capacity will depend on the specific geological site selected.

Each AirBattery cavern could store compressed air equivalent to 3–8 GWh of electrical output, according to the company.

The exact figure for the first site has not yet been confirmed.

Germany to install first commercial AirBattery system: Summary

Augwind Energy has announced plans to build a commercial AirBattery system in Germany.

The system will store compressed air in underground salt caverns to generate electricity.

Air will be compressed using surplus wind and solar energy.

The company said each unit may store 3–8 GWh depending on site conditions.

Compressed air can be stored for several months.

The project cost will range between €7 million and €15 million.

The installation phase will last 9–12 months, followed by 3–6 months for commissioning.

The system will use 3 or 4 turbines generating 3–10 MW.

Lithium-ion batteries will support the system for ancillary services.

Projected storage cost is 10–15 USD per kWh.

No specific customers have yet been named.

The project aims to support Germany’s long-duration storage needs.

CLOU Electronics completes TS-800 fire safety test for Aqua-C2.5 energy storage system

by Featured NewsSafetySustainability

Fire safety test evaluates CLOU Aqua-C2.5 system performance in dense station layout

CLOU Electronics has reported that its Aqua-C2.5 utility-scale energy storage system completed the CSA TS-800 Large-Scale Fire Test (LSFT) in February 2025.

The test, conducted in California under CSA Group supervision, evaluated the system’s capacity to limit thermal runaway propagation under simulated fire conditions.

The company stated that the Aqua-C2.5 is the first large-scale energy storage system to feature an active ventilation fire protection design.

Test simulates extreme thermal and spacing conditions

According to CLOU Electronics, the Aqua-C2.5 was tested using a configuration that replicated real-world station layouts.

Four 20-foot containers were positioned in an A/B A/D array, placed closely side-by-side and back-to-back at a spacing of 140 mm.

The arrangement was fully loaded to replicate operational stress.

During the trial, temperatures inside the cabinet exceeded 1000°C and burned continuously for 48 hours.

CLOU Electronics said adjacent cabinets maintained internal temperatures below 40°C due to the system’s active ventilation and off-gassing features.

CSA Group outlines limitations of previous standards

The TS-800 protocol was released in 2024 by the CSA Group to evaluate large-scale fire behaviour in energy storage systems.

Marvin Peng, Battery & Energy Storage Certifier at CSA Group, said: “The existing standards (such as UL 9540A) are capable of testing for thermal runaway, but they do not adequately simulate fire propagation scenarios, especially in multi-module container systems where a single battery fire can potentially ignite adjacent units or even the entire system.

“The core goal of the TS-800 test is to address this gap.”

CLOU highlights design features and certifications

Eric Wang, System Director of CLOU ESS Division, said: “CLOU committees that every product delivered is trustworthy and has undergone rigorous testing.

“The Aqua-C2.5 5MWh utility scaled energy storage system is the world’s first large-scale energy storage system to adopt an active ventilation fire protection design.

“Through active cell sensing, it triggers an electric shutter explosion suppression solution in thermal runaway scenarios, effectively controlling the spread of thermal runaway at extreme short distances in 140mm.”

The Aqua-C2.5, launched in September 2024, has received certifications including CE, UL1973, UL9540A, UL9540, IEC62619, IEC63056, IEC62477-1, UN38.3, NFPA855 and NEC.

It has also passed the IEEE693 seismic test.

Sungrow and other manufacturers also complete TS-800 testing

Other manufacturers have also conducted the TS-800 fire safety tests for their energy storage systems.

In 2024, Sungrow reported that its liquid-cooled system endured four hours of combustion in an A/B array without fire spreading to surrounding equipment.

Sungrow cited the use of pressure-sensing venting, multi-layer fire resistance and dual-compartment design in its PowerTitan system.

The company stated that its next-generation PowerTitan 2.0 product passed the large-scale test.

Trina Storage and BYD also reported completing the TS-800 fire test in October 2024 and January 2025 respectively.

CLOU Electronics completes TS-800 fire safety test for Aqua-C2.5 energy storage system: Summary

CLOU Electronics reported in February 2025 that its Aqua-C2.5 system completed the CSA TS-800 fire test.

The test evaluated fire propagation and containment in high-density energy storage system layouts.

It was conducted under CSA Group supervision using a layout replicating real station conditions.

Temperatures inside the tested cabinet exceeded 1000°C and burned for 48 hours.

Adjacent cabinets remained below 40°C due to active ventilation and off-gassing.

CSA Group launched the TS-800 standard in 2024 to test fire behaviour in multi-module systems.

Marvin Peng of CSA Group said current standards do not fully address fire propagation scenarios.

CLOU stated the Aqua-C2.5 is the first to use active ventilation fire protection.

The system includes electric shutter suppression and thermal detection features.

It holds multiple safety and compliance certifications including UL9540A and IEEE693.

Other manufacturers, including Sungrow, Trina Storage and BYD, also completed TS-800 testing.

Sungrow reported successful tests using its PowerTitan system and next-generation models.

Bridging the fire protection gaps: Fire and explosion risks in grid-scale battery storage

by Featured News

Bishoy N. Awad, Karli Steranka and Ulises Rojas-Alva assess fire and explosion risks in grid-scale BESS and the challenges of standardising hazard mitigation techniques

Introduction

The challenges of providing effective fire and explosion hazard mitigation strategies for Battery Energy Storage Systems (BESS) are receiving appreciable attention, given that renewable energy production has evolved significantly in recent years and is projected to account for 80% of new power generation capacity in 2030 (WEO, 2023).

This acceleration towards renewable energy adoption has contributed to the growing imbalance between electricity demand and renewable energy generation solutions (e.g., solar power plants) due to the misalignment between supply and demand (Bowers et al., 2023).

One of the robust and reliable solutions for this imbalance is BESS, which can be used to store energy generated during low demand for use during high demand periods.

In the US, the cumulative BESS capacity has increased since 2015, with 11.9 GW installed in 2024 (Martin et al., 2025).

A significant growth in BESS installation is anticipated worldwide, with over 1 TWh of new installations between 2023 and 2025 (Martin et al., 2025).

Figure 1 shows this increasing trend in global battery deployment and directly plots the battery failure rate per deployed GW of battery energy.

This graph shows an overall decrease in battery failures per GW installed with increasing installations.

Despite the global decrease in battery failure rates per GW installed, the deployment of BESS technology is hindered due to inherent fire and explosion hazards, public fear due to misinformation, and knowledge gaps in the fire safety industry, including a lack of clear guidelines or standards for the safety design of BESS across various applications.

Figure 1 Global Grid-Scale BESS Deployment and Failure Statistics (ERPI Failure Incident Database, Wood Mackenzie)

BESS Hazards

Lithium-ion (Li-ion) battery technology is commonly used for stationary grid scale BESS and poses inherent fire safety hazards due to li-ion battery failure.

Li-ion batteries can fail due to physical abuse (e.g., puncture, deformation and/or exposure to elevated temperatures), electrical abuse (e.g., short circuity and/or overcharge), or manufacturing defects.

As a result, the battery generates heat and releases flammable battery vent gas.

This phenomenon can lead to thermal runaway.

Thermal runaway is a condition in which a self-heating chemical reaction occurs within the battery cell and releases flammable vent gas from the battery cell.

The battery gases released during thermal runaway vary in composition based on the battery chemistry (e.g., lithium-cobalt oxide (LCO) and lithium-iron-phosphate (LFP)), form factor, state of charge and manufacturer (Baird et al., 2020).

Depending on the installation conditions, thermal runaway may be limited to the initiating cell(s), or thermal runaway may propagate to adjacent cells due to conductive and convective heating or physical damage to adjacent cells due to swelling of the initiating cell.

Thermal runaway propagation can occur without oxygen and a flame (Gagnon, 2024).

The primary hazards posed by BESS are the flammable vent gases and heat generation associated with thermal runaway.

Figure 2 provides a high-level diagram of a battery failure scenarios and event pathways which lead to varying consequences.

As shown in the figure, the consequences associated with thermal runaway vary depending on multiple factors, including the point at which the battery gas reaches a competent ignition source.

Additionally, the severity of consequences depends on multiple factors, including but not limited to the initiating event, vent gas composition, state of charge, ambient conditions, installation conditions, and mitigation techniques (Jin et al., 2021).

Figure 2. Battery failure scenarios

Mitigating Technologies & Approaches

The consequences associated with a BESS failure can be reduced with appropriate mitigation techniques and emergency response.

Mitigation techniques can be subdivided into passive and active protection methods.

Passive techniques typically reduce the likelihood of a consequence and provide passive protection to reduce the severity of consequences.

Active techniques focus on preventing an explosive atmosphere and providing active cooling to reduce the severity of thermal effects.

Figure 3 provides an overview of passive and active mitigation techniques.

Figure 3. Passive and active mitigation techniques

Explosion hazard mitigation for BESS typically involves deflagration venting in accordance with NFPA 68, Standard on Explosion Protection by Deflagration, emergency ventilation system in accordance with NFPA 69, Standard on Explosion Prevention Systems, or a novel explosion protection system based on full-scale testing.

Because explosion control mitigation design requires the design engineer to make critical assumptions regarding the quantity of vent gas and vent gas composition, better characterization is needed on the quantity and composition of flammable gases to support the design of these systems (Long, 2021).

Typical explosion mitigation techniques are shown in Figure 4.

Figure 4. Explosion hazard mitigation techniques

Fire hazard mitigation is typically provided via active suppression systems or passive exposure protection techniques.

There are no proven fire suppression methods to extinguish li-ion battery fires.

It is recommended that BESS fires burn in a controlled environment and that exposure control is provided to mitigate property and life safety hazards from the fire by reducing the radiant heat flux and pre-wetting adjacent combustibles to prevent fire spread.

Separation distances provided between BESS cabinets can also be used as a passive mitigation technique to reduce the thermal exposure from a fire event and limit container-to-container propagation, as proven by FM Global large-scale fire test (Ditch & Zeng, 2020).

Typical fire hazard mitigation techniques are shown in Figure 5.

Figure 5. Fire hazard mitigation techniques

Figure 6 shows computational fluid dynamic modelling results demonstrating the effectiveness of exposure control cooling water on the incident heat flux exposure at the exterior of a target BESS.

Figure 7 shows an iso-contour of an incident heat flux of 12 kW/m² and the impact of the separation distance on target units.

Figure 6. Target BESS exterior heat flux and TR propagation analysis with & without exposure cooling.

Figure 7. 12 kW/m2 heat flux contour vs BESS separation distance.

Although there are commonly accepted mitigation techniques, there is no widespread industry standard or code requirement for the design of these systems, which leads to significant variations in the level of safety provided between BESS products.

There is a need for widespread guidance to support BESS safety system designers for uniformity among BESS products.

EPRI, Fire and Risk Alliance, and RISE have all published explosion control guidance, which can be referenced in lieu of current formal guidance (Grönlund et al., 2023; Lauren Gagnon, 2024; Long, 2021).

Summary and outlook

BESS safety involves mitigating explosion and fire hazards through various techniques such as deflagration venting, emergency ventilation, and exposure protection.

Techniques for explosion mitigation include vent gas characterization and full-scale testing, while fire mitigation involves active suppression systems or passive exposure protection.

There are no proven methods to extinguish lithium-ion battery fires, so controlled burning and separation distances are recommended to prevent fire spread.

The future of BESS technology is promising, with expected growth in installations worldwide.

Ensuring safety is crucial for widespread adoption, and comprehensive guidance and standards are needed for uniform safety measures.

Effective mitigation techniques and improved safety design guidelines can help the industry overcome challenges and realize the potential of BESS in supporting renewable energy solutions.

Authors

Bishoy Awad, Karli Steranka, & Ulises Rojas-Alva

Affiliations

Fire & Risk Alliance, Department for Fire-Safe Sustainable Built Environment (FRISSBE), Slovenian National Building and Civil Engineering Institute (ZAG)

References

Baird, A. R., Archibald, E. J., Marr, K. C., & Ezekoye, O. A. (2020). Explosion hazards from lithium-ion battery vent gas. Journal of Power Sources, 446. https://doi.org/10.1016/j.jpowsour.2019.227257

Bowers, R., Fasching, E., & Antonio, K. (2023). As solar capacity grows, duck curves are getting deeper in California. US Energy Information Administration, Today in Energy.

Ditch, B., & Zeng, D. (2020). Development of Sprinkler Protection Guidance for Lithium Ion Based Energy Storage Systems.

Grönlund, O., Quant, M., Rasmussen, M., Willstrand, O., & Hynynen, J. (2023). Guidelines for the fire protection of battery energy storage systems (Rise Division Safety and Transport Fire Safe Transport, Ed.). RISE Research Institutes of Sweden AB.

Jin, Y., Zhao, Z., Miao, S., Wang, Q., Sun, L., & Lu, H. (2021). Explosion hazards study of grid-scale lithium-ion battery energy storage station. Journal of Energy Storage, 42. https://doi.org/10.1016/j.est.2021.102987

Gagnon, L.. (2024). Explosion Control Guidance for Battery Energy Storage Systems Overview of Current Standards and Additional Recommendations. www.fireriskalliance.com

Long, D. (2021). Battery Energy Storage Systems Explosion Hazards.

Martin, H., Wang, C., & Buckley, T. (2025). International Solar PV and BESS Manufacturing Trends.

This article was originally published in the May 2025 issue of International Fire & Safety Journal – to read your FREE digital copy, click here.

Energy Vault closes $28 million in funding for wildfire-resilient microgrid in California

by Featured NewsProjectsSafetySustainabilityWildland Fire

Calistoga Resiliency Center receives $28 million project financing

Energy Vault Holdings has secured $28 million in project financing for the Calistoga Resiliency Center (CRC) in California, according to a press release published by Energy Vault Holdings.

The financing includes the completed sale of an Investment Tax Credit (ITC) tied to the project.

This facility has been developed to support Pacific Gas and Electric Company (PG&E) through a tolling agreement.

The hybrid microgrid combines green hydrogen fuel cells with lithium-ion batteries to provide continuous energy during Public Safety Power Shutoff (PSPS) events, which are used to reduce wildfire ignition risk during extreme weather.

Energy Vault confirmed that mechanical completion has been achieved and that the system is currently in commissioning.

Full commercial operation is expected in the second quarter of 2025.

Wildfire risk drives need for grid-resilient systems in California

The CRC was designed to address wildfire-related power shutoffs, which have become more common in California due to climate-related conditions.

The system supports isolated operation during PSPS events, supplying power to the Calistoga community without emissions.

The 293 MWh facility delivers approximately 48 hours of energy supply with 8.5 MW of peak power.

When disconnected from the grid, the system uses green hydrogen for generation and battery storage for stability and response.

System integrates hydrogen and battery storage technologies

Energy Vault stated that its CRC is the first ultra-long duration hybrid microgrid combining hydrogen and battery technology for utility-scale use.

Its proprietary B-VAULT DC battery technology works alongside hydrogen fuel cells to ensure uninterrupted power and system stability.

The facility is managed by Energy Vault’s VaultOS energy management platform, which provides black-start capability and grid forming control.

This platform communicates directly with PG&E’s Distribution Control Center during operation.

Commercial operation to begin in 2025 under Energy Vault ownership model

The CRC is part of Energy Vault’s shift to owning and operating its storage assets, first detailed in May 2024.

The company aims to create recurring revenue through tolling agreements with utilities.

Robert Piconi, Energy Vault’s CEO, said: “The successful financing of the Calistoga Resiliency Center represents our team’s focus and execution in beginning 2025 by replenishing cash to our balance sheet from the prior year capex spent building the system.”

Piconi added: “As California faces increasing wildfire risks, the CRC demonstrates how advanced energy storage technology can help communities maintain critical services and safety during necessary power shutoffs.”

The company has also announced agreements to monetise tax credits and secure funding for other projects in Texas, including the Cross Trails and Customer R&D Center microgrid.

Energy Vault closes $28 million in funding for wildfire-resilient microgrid in California: Summary

Energy Vault Holdings has confirmed $28 million in financing for its Calistoga Resiliency Center, which includes the sale of an Investment Tax Credit.

The CRC is a microgrid in California that combines hydrogen fuel cells with lithium-ion batteries.

It is designed to support PG&E during Public Safety Power Shutoff events.

The system provides 293 MWh of energy and delivers 8.5 MW of peak power.

It operates without emissions and allows the Calistoga community to maintain power during wildfire-related outages.

The facility uses Energy Vault’s B-VAULT battery technology and VaultOS energy management platform.

It achieved mechanical completion and is under commissioning.

Commercial operation is planned for the second quarter of 2025.

The project aligns with California’s Renewable Portfolio Standard.

It is the first in a series of Energy Vault assets being launched under its ownership and operation model.

Additional financing and tax credit monetisation have been announced for projects in Texas.

Billion Watts Technologies enhances fire safety in Taiwan’s 64MW energy storage site

by Featured NewsProjectsSafety

Billion Watts Technologies commissions 64MW energy storage site in Taiwan

Billion Watts Technologies, a subsidiary of Billion Electric, has completed a 64MW/262.43MWh energy storage facility in central Taiwan.

The project, developed with Shinshin Credit Corporation, became operational in March and supports Taiwan Power Company’s E-dReg ancillary services market.

The facility contributes to grid stability by providing energy shifting and frequency regulation.

With a response time of 200 milliseconds, it helps manage fluctuations and ensures efficient power supply during peak demand periods.

Fire protection systems integrated into energy storage infrastructure

Billion Watts Technologies has incorporated fire safety measures into the site’s design to meet regulatory and operational safety standards.

The facility features dedicated firewalls, safety distance planning, and on-site water reserves.

A fire suppression system has been installed to detect and mitigate potential fire risks.

Real-time monitoring and anomaly detection further enhance safety by allowing early intervention.

These measures set new benchmarks for fire protection in Taiwan’s energy storage sector.

Energy storage supports Taiwan’s renewable energy transition

The facility can store enough electricity to power approximately 26,000 households daily.

As Taiwan increases its reliance on renewable energy, large-scale battery storage solutions are needed to manage fluctuations in solar and wind power generation.

According to Taiwan’s Energy Administration, renewables accounted for 11.6% of the country’s electricity supply in 2024.

The International Energy Agency has highlighted battery storage as a critical component for ensuring grid stability during Taiwan’s transition to low-carbon energy.

Billion Watts expands energy storage projects in Japan and Australia

Billion Watts Technologies is expanding its operations to Japan and Australia, aiming to meet growing demand for energy storage solutions.

In Japan, the company plans to develop high-voltage storage stations and deploy 1,000 commercial and industrial storage systems over the next three years.

In Australia, Billion Watts is participating in the National Electricity Market, targeting ten sub-5MW site acquisitions by 2026.

The company is also exploring investments in projects exceeding 50MW to capitalise on price volatility driven by renewable energy adoption.

Billion Watts Technologies enhances fire safety in Taiwan’s 64MW energy storage site: Summary

Billion Watts Technologies has commissioned a 64MW/262.43MWh energy storage facility in Taiwan, designed to improve grid stability and support renewable energy integration.

The project, developed with Shinshin Credit Corporation, officially began operations in March.

The site features advanced fire suppression measures, including firewalls, safety distance planning, dedicated water reserves, and real-time monitoring.

These measures enhance operational safety and set new industry standards for fire protection in energy storage facilities.

The facility provides grid flexibility by storing enough electricity to power approximately 26,000 households daily.

Taiwan’s Energy Administration reports that renewable energy accounted for 11.6% of the country’s electricity supply in 2024, increasing the need for stable storage solutions.

Billion Watts Technologies is also expanding its energy storage projects in Japan and Australia, focusing on high-voltage storage stations and participation in Australia’s National Electricity Market.

Wärtsilä enhances fire safety and noise control in energy storage systems

by Featured NewsPassive

Wärtsilä exceeds fire safety standards with large-scale testing

According to Wärtsilä, the company has introduced advancements in fire safety and noise mitigation for its Quantum energy storage systems (ESS).

These updates aim to help customers comply with evolving regulations while reducing environmental impact.

The company has conducted extensive large-scale fire testing of its Quantum High Energy and Quantum2 ESS units, surpassing the requirements of the UL 9540A testing standards.

In collaboration with the CSA Group, Wärtsilä performed two additional rounds of fire testing.

This involved igniting the enclosures until the fire sustained itself, simulating a worst-case scenario.

Test results indicated that the Quantum High Energy and Quantum2 units self-contained the fire, preventing it from spreading to adjacent units and keeping module temperatures below cell venting thresholds.

Test approach aligns with industry safety and regulatory standards

Wärtsilä’s recent testing meets the intent of updated standards, including NFPA 855 2026 and the CSA TS-800 standard.

These standards set benchmarks for energy storage safety, specifically addressing the prevention of fire propagation.

“Large scale energy storage system installations must address the safety concerns of the broader community,” said Josh Dinaburg, Fire Test Specialist at CSA Group.

He noted that Wärtsilä’s design prevents fire spread, allowing local fire services to contain and control incidents.

The tests were observed by stakeholders, including utility representatives, fire consultants, and insurance engineers, who assessed the systems’ response.

Chris Groves, Wärtsilä’s Product Manager for Safety Engineering, said: “These new fire safety measures demonstrate our commitment to going above and beyond existing industry standards.”

Commitment to community safety with noise control advancements

In addition to fire safety, Wärtsilä has prioritised noise mitigation, addressing concerns in residential areas near ESS sites.

Wärtsilä’s systems now incorporate noise control measures, such as fan speed adjustments, to meet local noise limits.

These measures also undergo verification by third-party consultants, providing assurance of compliance with specific community standards.

As energy storage installations expand, these noise reduction measures are designed to minimise disturbances.

Wärtsilä stated that its operational controls and customisable noise attenuation solutions enable clients to adapt the systems to site-specific requirements.

Collaborative development of tailored safety solutions

Wärtsilä has involved clients in developing these fire safety and noise control systems to ensure they align with both safety standards and site-specific needs.

Fadi Zara, Program Manager at Wärtsilä Energy Storage and Optimisation, stated: “Close collaboration with clients allows us to develop tailored noise reduction solutions, such as low fan speed controls and third-party-verified noise attenuation solutions.”

Stakeholders and industry experts have supported Wärtsilä’s safety-focused approach.

Paul Hayes, Vice President of Energy Structure at Hiller Companies, commented: “This reassures us of their commitment to safety and instils confidence in their capabilities.”

Wärtsilä enhances fire safety and noise control in energy storage systems: Summary

Wärtsilä has introduced new fire safety and noise control measures for its Quantum energy storage systems to meet changing regulatory standards and minimise environmental impacts.

Following two additional rounds of large-scale fire tests, Wärtsilä’s systems surpassed the UL 9540A standards, containing fires within the initiating units and preventing spread to adjacent ones.

These measures comply with standards including NFPA 855 and the forthcoming CSA TS-800.

The company has also prioritised noise mitigation to address community concerns, using adjustable fan controls and third-party-verified noise assessments to ensure compliance with local regulations.

Industry experts and stakeholders have commended Wärtsilä’s commitment to safety, with clients able to tailor these systems to specific site requirements.

Safer storage systems

by Breaking NewsSafety

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.