A look at the data and literature around Failures and Fires in BESS Systems. The number of fires in Battery Energy Storage Systems (BESS) is decreasing [1].
Between 2017 and 2022, U.S. energy storage deployments increased by more than 18 times, from 645 MWh to 12,191 MWh, while worldwide safety events over the same period increased by a much smaller number, from two to 12.
Claims vs. Facts: Energy Storage Safety, American Clean Power
DNV in their report [2] have learned that many BESS fires are the result of design and implementation details. Not because of faulty lithium-ion cells, or abuse by overcharging those cells, but instead were triggered by the cell’s operating environment, including:
- faulty control of humidity within enclosures that led to condensation on sensitive components
- poorly sealed enclosures that led to rain penetration
- combustible meltable components made of plastics and aluminium that can contribute to fire propagation
The EPRI’s database and collection of data from failures shows that the failure rate has dropped dramatically. A detailed report has been compiled of the failures [4]. The high level abstract makes the following conclusion:
- 46% controls
- 43% balance-of-system components
- 11% cell failures
The pie chart shows the breakdown of BESS failures by Root Cause [4].
This post has been built based on the support of and sponsorship from: Quarto Technical Services, Eatron Technologies and About:Energy
DNV [2] give detailed examples of two failures:
- The July 2021 Victorian Big Battery (Australia) fire involved 2 Tesla Megapacks in a 212-unit site. An investigation found that, during commissioning of the units, a leak in one unit’s liquid cooling system caused arcing between battery modules. Heat from that arcing led to thermal runaway of cells in that unit. While the unit’s insulated walls appeared to prevent fire spreading to an adjacent unit 15 cm away, winds drove flames from the roof of one unit to a neighbouring one where they ignited plastic components on the roof, allowing flames to reach the batteries below.
- A June 2023 fire in Warwick, New York, USA, where the local Board of Education (which hosts the BESS on its property) received a report from the BESS owner stating that rainwater seeped into battery containers, resulting in an electrical short and fire.
The EPRI table [4] of recommendations and mitigations (not exhaustive or complete) by root cause.
The reduction in failures shows that progress has been made at every stage and the national and international standards are improving the design and delivering of every aspect of the BESS. However, we need to be focused on continuous improvement, documenting failures and ensuring the knowledge is embedded back into standards and design guides.
References
- Claims vs. Facts: Energy Storage Safety, American Clean Power
- 2024 Battery Scorecard, DNV
- BESS Failure Incident Database, Storagewiki
- Insights from EPRI’s Battery Energy Storage Systems (BESS) Failure Incident Database: Analysis of Failure Root Cause, EPRI
See also: UL 9540