Reducing Fire Risk for Battery Energy Storage Systems and Electric Vehicles

As part of the quest to decarbonize, energy utilities and electric power producers are rapidly increasing the proportion of energy generated with wind and solar resources.

Because wind and solar are intermittent, there is a parallel push to install large-scale batteries to store surplus electricity at times of low demand and dispatch it during periods of high demand.

However, the rapid growth in large-scale battery energy storage systems (BESS) is occurring without adequate attention to preventing fires and explosions.

The U.S. Energy Information Administration estimates that by the end of 2023, 10,000 megawatts (MW) of BESS will be energizing U.S. electric grids—10 times the cumulative capacity installed in 2019.

“The development of this technology is happening so fast that testing agencies and local authorities having jurisdiction (AHJs), can’t keep up with the fire safety issues,” said Justin Milne, WSP lead consultant, fire and life safety.

Milne and his colleagues point to a tragic fire and explosion that occurred in April 2019 at an Arizona Public Service BESS facility in Surprise, Arizona as an example of the hazards that need to be addressed. One lithium-ion cell in the BESS failed and triggered a thermal runaway event that cascaded to other cells, releasing flammable gases within the sealed BESS container.

“When firefighters opened the door a couple hours later, oxygen filled the room and led to an explosion that threw the firefighters back as much as 75 feet,” said Vincent Favale, who also serves as a fire and life safety lead consultant at WSP.

According to a report for Arizona Public Service by DNV GL, a clean agent fire suppression system within the BESS container had deployed correctly, but the report determined that it was the wrong system for a battery fire. The report also concluded that the lack of thermal barriers between cells “contributed to the cascading cell-to-cell thermal runaway” and that firefighters weren’t adequately prepared and trained to deal with a BESS fire.

While a comparable disaster has not recurred in the U.S., Favale and Milne fear that even worse accidents could be on the horizon without greater attention to fire safety by the BESS industry.

More fires could also stall the growth of BESS capacity and hamper the transition to clean renewable power. South Korea serves as a cautionary tale in this regard: after a series of fires through 2019, hundreds of operating BESS units were taken offline temporarily and growth of BESS slowed dramatically. This underscores the need to include fire protection specialists as part of the project team.

WSP’s fire protection specialists work in multidisciplinary teams on BESS projects, primarily for electric utilities, and more recently, with public transit agencies transitioning to battery electric buses.

“Public agencies must approach any new technology that poses a safety risk with caution, including BESS, and take appropriate risk management precautions,” Milne said. “A formal risk assessment, fire modeling or full-scale testing should be conducted to investigate an unexplored foreseeable risk. Qualified individuals can then ensure a sound engineering design.”

Three primary concerns related to BESS include:

1. Manufacturers are developing new BESS technologies and configurations so quickly that testing firms are backlogged with demand, and few can handle larger systems.
2. Like the clean agent system in the Arizona BESS, fire suppression technology incorporated into BESS units is frequently inadequate. “We’ve even seen aerosol systems in some of these systems,” Favale said. “Because aerosol generates heat, this is a terrible technology to suppress a battery fire.”
3. The National Fire Protection Association 855 standard for installing stationary energy storage systems was created in 2020 and has to date not been incorporated in any AHJ’s fire codes.

In New York City, where Favale works, The Fire Department of New York (FDNY) has developed its own comprehensive fire codes and standards for BESS, which WSP considers to be the best and most comprehensive established to date in the U.S.

“They have rules for setbacks from public right of way, space required between BESS containers, types of fire suppression systems, how to set up a fire department staging area, alarms and emergency stop buttons,” Favale said.

It has been a challenge to make fire protection a priority for some battery manufacturers, he added. “They are focused on improving the power density of their batteries, which can increase fire risk without adequate mitigation.”

There will be continued need for AHJs to develop their own codes and enforcement protocols. WSP has more than 250 fire protection engineers, including about 30 in the U.S. who are working with clients on a multitude of fire safety risk and prevention issues.

Fire protection engineering services is an area where the firm expects to experience significant growth as these issues become more critical to projects. Forward-thinking organizations recognize that the rapid development of energy storage technology demands Future Ready™ approaches to fire protection in tandem with developing innovative and sustainable alternative energy resources.

Milne and Favale are also quick to clarify that consumer grade, residential BESS systems, such as the Tesla Powerwall, do not present the same level of fire and explosion dangers as large-scale systems.

“They’re producing a much lower power density, and the manufacturers have done extensive testing to reduce the hazards, which I’ve reviewed,” Favale said.

However, fires from electric vehicle batteries are a concern both for occupants of the vehicle and concrete parking structures.

“Heat from an electric vehicle fire is more intense than that from a gasoline fire, and it could superheat the structure of a parking garage to the point where concrete spalling occurs,” Milne said. “We have seen parking garage structures condemned following a vehicle fire event; this hazard is magnified with electric vehicles.”

For this reason, it is important to consider future electric vehicle use when designing today’s parking garages. “This could include conducting a more robust evaluation of the true fuel loads if EVs catch fire,” Milne said. “A design response could include increasing the floor-to-floor height of the parking garage.”

Recognizing the fire risks batteries can pose to the public and firefighters is critical. If the coming electric battery revolution is to be truly successful and game changing, it must also be accompanied by responsible fire protection engineering and the awareness, codes and procedures to ensure these guidelines are in place at every facility using these power sources.

The observance of Fire Prevention Week in the U.S. and Canada began on Oct. 3 and continues through Fire Prevention Day on Oct. 9. It has been observed annually in the U.S. since 1925, drawing attention to lifesaving educational initiatives to decrease casualties caused by fires.

[To subscribe to Insights, contact the editorial staff at [email protected].]