With energy storage batteries being adopted very quickly, there are some concerns about their fire safety, especially the potential for fires in batteries used for residential storage applications.
The National Fire Protection Association is studying how to best train firefighters to respond to fires in homes and businesses that contain energy storage systems, said Matt Paiss, a San Jose firefighter and consultant to NFPA. Paiss is helping develop the training materials for the project, which is funded through a two-year federal grant. He’s also working with the National Association of Firefighters to create appropriate codes under the National Electric Code.
One of the main concerns is how quickly energy storage systems are being adapted—more quickly than policymakers can create standards for them, he said. Many new microgrids include battery energy storage.
UL, which categorizes energy storage systems as “stationary equipment,” has not formally completed its standards for this type of system, he said.
“When stationary equipment is put into dwellings, we a need higher reliability standard. That’s our concern,” he said.
A few fires in energy storage systems have occurred, he noted. “They’ve been primarily lead acid and some fires with sodium sulfur in Japan.”
However, lithium ion batteries are a focus at this time because their cell structures can be very dense—and susceptible to explosive fires under certain circumstances, he explained. “It comes down to energy density; the tighter you put the cells together, the harder it is to stop the propagation of a fire.”
At a recent conference, Paiss was disappointed and surprised at the number of battery manufacturers who said their batteries don’t catch fire. “It’s claims like this that hurt the industry; any lithium ion chemistry can support a thermal runaway.”
Thermal runaway, he said, is the failure of one cell that results in the cell catching fire and neighboring cells catching fire. When that happens, the fire runs through an entire module.
“When lithium ion burns, it creates its own oxygen. It can create a violent explosion, depending on the chemistry,” he said. “The cells can explode when they overheat. If you take 20 or 30 of those cells and subject them to heat when you’re testing the cells, you can have huge amounts of toxins and flammables.”
Some of the batteries are produced to be more stable than others, he noted.
Bill Daly, president of Apogee Power, claimed that his lithium ion battery is produced in a way that prevents fires—and that his company is one of the few companies that can pass fire safety tests.
“Our technology has a system that monitors each cell and the entire collection of cells in the box. It stops shorting, thermal runaway and over charging, among many other features. Those items are the three primary causes of fires with lithium ion batteries,” he said.
And like Paiss, he said that testing has not yet caught up with the technology.
Battery manufacturers should consider supporting the research that’s needed to determine how best to ensure fire safety, said Paiss.
“One of the real unknowns is what type of fire protection systems should be put in large battery rooms in high-rise residential dwellings. We haven’t been able to determine what type of sprinkler systems should be used and how they get installed. This is an expensive understanding and needs to be done.” In addition, Paiss said, there’s need for research to understand whether it’s safe to allow for re-purposed auto batteries in homes.
Said Daly, “People don’t realize how unsafe lithium ion can be.” Putting energy storage systems with lithium ion batteries in people’s homes at this time, he said, is “gambling.”
