» View our BESS webinar we coordinated with our Mass Clean Peak Coalition colleagues, tailored for Massachusetts communities.
Battery systems can be used to store energy from renewable sources, like wind and solar, to be released when the electric grid needs extra power.
There have been questions about the safety of battery storage, many of which arise because of uncertainty about the differences between Battery Energy Storage Systems and Commercial Lithium Batteries. This chart can help explain:
Battery Energy Storage Systems vs Commercial Lithium Batteries | |
|---|---|
Battery energy storage systems (BESS) have to follow fire prevention building code regulations | There are no real actionable standards in place for commercial lithium batteries like those in e-bikes |
Large BESS units are protected against the elements because they are cased in weather-proof containers. BESS don’t move locations so they lack the risks found with mobile battery packs (like those in E-bikes | Easily damaged by external factors, drops, overheating, overcharging, rapid use, and water damage that can all lead to explosion |
BESS units have more specific safety systems on site to deal with failure and fire/explosion risk. | When fire or explosion occurs traditional fire extinguishing techniques may be of little help. Many apartments are not fitted with fire suppression systems that can handle battery fires. |
BESS have more building regulations to adhere to so are generally made with higher quality materials with greater stability (generally higher industry standards). | The materials found in small scale commercial lithium batteries can often be made with lower quality materials increasing risk of failure. |
Higher end BESS units use smart software to ensure the input and outflow of energy happens at a regulated pace. | Charging and discharging of energy stored in the battery is fully in the manual control of the user, exposing the battery to greater failure risks. |
Thanks to Shelley Robbins of Clean Energy Group and Victor Davila of The Point CDC for the information in this chart.
What about safety issues with grid-scale battery storage (BESS)?
Most news headlines about deadly battery fires refer to the batteries used for “mini-mobility” vehicles, primarily e-bikes and scooters. New regulations are coming into effect which will ensure that low-quality components and shoddy manufacturing techniques that have been used in less expensive e-bikes and scooters are eliminated, which will help ensure that incidents become far less common.
Larger grid batteries have a better track record. The California Public Utilities Commission estimates that only around 2 percent of grid storage facilities will experience major safety-related incidents, with the risk greatest during the first two years of operation. While lithium ion battery fires have gained media attention, the technology’s overall safety record is strong and continuously improving.
The Electric Power Research Institute (EPRI)’s BESS Failure Database tracks failure events in grid-scale storage worldwide. Over the last 4 years, there have been on average 10 such failure events annually, even as global battery deployments have have grown twenty-fold.
10-15 safety events a year may sound like a lot, until you realize that those numbers are dwarfed by those in the fossil fuel industry. Pipes transporting natural gas cause thousands of explosions in the US each year.
Other improvements, including lithium-free designs with lower fire risks, will be arriving on the grid in a few years.
Even with the rapid growth in deployments, failure incidents in grid-scale battery storage are infrequent, and are avoidable using the lessons learned from past incidents to further reduce the possibility of future accidents as they are applied to new storage facilities and integrated into building and fire codes and standards.
BATTERY CHEMISTRY COMPARISONS:
Lithium based:
• NMC = Lithium Nickel Manganese Cobalt Oxide: Packs more power in less space. Less stable (old style BESS, prone to thermal runaway), needs careful charging monitoring (over 90% can trigger thermal runaway), less tolerant temperature range (temp extremes can cause thermal runaway), shorter life, toxic and more rare components like cobalt that often have impacts for mining at the source as well.
• LFP = Lithium Iron Phosphate: Substantially less fire risk, can charge to 100% safely, stable over wide range of temperatures, common / more abundant elements.
The only application where NMC is beneficial is where high power in less space with less weight is beneficial, i.e. works best for high-performance / high range EVs. Notably LFPs can also be used for standard-range EVs with much greater safety.
BESS developers should not be proposing NMC batteries. Their track record for safety in BESS applications is bad. The vast drop in BESS thermal runaway incidents is largely due to the rise of LFP deployment and increases in safety measures.
Any lithium-based battery system should include thermal sensing and fire suppression in each unit. They should also adhere to insurance recommendations for sufficient spacing of units to prevent any fire from spreading between units (more info below). Lithium mining remains an environmental concern as well.
BEAT / No Fracked Gas in Mass supports non-lithium BESS development, especially non-toxic, non-flammable iron-based systems.
Non-lithium:
• Iron flow: Comprised of iron, salt and water. Non-flammable, non-toxic. Long duration (10+ hours though shorter duration possible if needed). Common / abundant materials. Can last for 20,000 cycles +. Power and energy capacity can be scaled by adjusting tank size and pumping rates.
Generally ranked as lower efficiency and density compared to others, but different configurations can fit a wide range of duration, density and space needs. Some companies working on developing alkaline iron flow batteries to improve performance.
ESS Tech has a highly dense configuration called EnergyBase™.
» Short video describing ESS iron flow tech
• Iron air: Comprised of iron that oxidizes to discharge energy then de-oxidizes to store energy (rusting and un-rusting). Non-flammable, non toxic. Extra long duration, lasting up to 100 hours. Low efficiency, much less dense, so they take up more space, but allows for extremely long-term power outage supply. Sole component is iron, extremely abundant. Form Energy is the main developer (MA based company).
• Zn-Br2 = Zinc bromine: Zinc plating and aqueous zinc bromide electrolite. “Generally not flammable”, bromine is toxic and corrosive, but system should be safe if property sealed and mixed with “complexing agents” like salt to prevent vapor release. Materials are recyclable. High density, lifetime in thousands of cycles.
• Zinc air: Zinc anode, air cathode (using porous cobalt oxide/carbon hybrid catalysts – small quantity), alakaline potassium hydroxide electrolye. Non-flammable. High energy density / high efficiency. Currently not long lifetime, innovations being developed.
BEST PRACTICES AND SAFETY ISSUES
• National Fire Protection Agency Latest Publication: NFPA 855 2026
• Clean Energy Group fact sheet, “Utility Scale Lithium-Ion Battery Storage Fire Safety: FAQ“
• SanDiego BESS safety best practices
• Everon™ (fire and security safety firm) has a fair amount of plain language info on BESS safety – how things go wrong and prevention systems. Also mentions international fire code, National Fire Protection Agency specs, and UL standard (specs you may want to require an installation to follow).
**Included here for reference, this is not an endorsement of Everon.
References:
https://storagewiki.epri.com/
https://www.wired.com/story/big-grid-batteries-are-booming-so-are-fears-fire/
https://ag.umass.edu/clean-energy/energy-storage-information
» Webinar about Battery Energy Storage Systems safety, EVLO Energy Storage
Resources:
https://rmi.org/clean-energy-101-how-batteries-can-support-grid-reliability/