Much has been made of battery fires, particularly those with lithium-ion (Li) chemistries. The attention is likely a result of the rapid growth in the Li battery energy storage industry. Some of this is media driven. In a relatively new industry, it’s easy to be sensational about fires. It’s more difficult to explain the broad amount of safety measures being implemented, measures we readily accept in other industries.
The initial reports about a recent Tesla Model S crash, for instance, described the resultant battery fire as burning intensely for four hours and consuming 30,000 gallons of water—unlike a “normal” fire that firefighters usually can tame in two or three minutes. Based on that report, other media outlets highlighted the concern for battery fires.
The next day, in contradiction, the local fire chief said that the fire indeed had been controlled within two or three minutes after firefighters arrived. To keep the batteries as cool as possible, they used small amounts of water periodically for four hours, following the guidelines Tesla provides to first responders, so that police could investigate the accident. In a statement, Tesla CEO Elon Musk said that other safety measures in the battery had worked as they should have, removing heat to prevent thermal runaway—that is, to prevent other parts of the battery module from catching fire in an uncontrollable manner.
Li batteries are the power source of choice for various applications, mobile and stationary. Stationary battery energy storage systems (which include residential, commercial, and utility-scale systems) often rely on more batteries than an EV. But while the applications for Li battery systems may vary, the battery technology is similar, and so are the fire hazards. And, in a way similar to EV systems, safety mechanisms are at work in larger battery systems on the grid and in other applications. The systems use structural and mechanical ways to keep batteries cool and prevent thermal runaway; and operators and manufacturers have safety protocols and provide training for responders.
In the stationary energy storage sector, recent fire incidents have led the industry to improve the safety associated with the systems deployed. A 2019 incident in Arizona provided a wake-up call to the industry, particularly in the United States. At the time of the incident, several industry best practices, standards, testing, and codes had yet to be accepted widely or even developed. However, since the National Fire Protection Association (NPFA) 855 “Standard for the Installation of Stationary Energy Storage Systems” was released in 2020, the industry has a best practice standard providing insight into existing and improving certifications, testing standards, and design standards, such as:
- UL 9540 – battery energy storage system certification
- UL 9540A – battery cell, module, rack-level thermal runaway test
- UL 1973– battery certification
- NFPA 68 and NFPA 69 – explosion protection and prevention design standards
These certifications, testing standards, and codes are listed as requirements of NFPA 855 for many Li energy storage systems. With this guidance, we have seen an increased focus on stationary energy storage system fire safety across the U.S. market.
While the 2020 edition of NPFA 855 focuses on stationary energy storage applications, the upcoming edition is expected to include guidance pertaining to EVs. As such, DNV anticipates that this will only bolster the already forward-looking and safety-minded Li-based EV market. It should be noted that several battery safety certifications, testing, and standards exist for EV batteries. These include UL 2580, UL 2271, and ISO 26262, among others.
It is one thing to say that Li fires can be dangerous. But the safety measures and precautions that manufacturers and project owners and operators take and that are carved in stone in warranties, contracts, standards, testing, and codes—the same kind that exist in internal combustion engines and natural gas peakers—are working. Also, battery fires are well understood, due to their resemblance to plastics fires, which ultimately share similar fire characteristics (e.g., toxicity). As such, similar measures and approaches can be taken to extinguish the fire.
The energy storage industry is young and constantly improving—and will continue to improve as it grows. Safety and proper mitigation measures must reside at the heart of Li battery system design. As in similar industries with fire risks, standards and planning are key—and manufacturers, operators, and first responders are working together to enhance protocols and training.
For more information, visit www.dnv.com/storage or read more about DNV’s battery safety, risk analysis, and permitting support.