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Dirk Long
Dirk Long
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Building the Path to Safer Battery Storage

Advancements in lithium-ion technology are driving widespread battery adoption, with broad applications for consumer, commercial, and industrial use. Over the years, the cost of lithium-ion battery storage continues to decline, while interest in renewable energy deployments increases. This environment makes the application and use of battery energy storage increasingly significant for electric power companies. To enable this growth, EPRI investigates battery health, safety, and environmental uses with the goal to provide best practices and key findings for owners, operators, and developers of energy storage. 


As an evolving technology, it is critical that codes, standards, and processes remain up to date to ensure the long-term safety, integrity, and viability of the product. Recognizing the potential risks when safety measures are hindered, two years ago EPRI began a new project focused specifically on analyzing battery fire threats, consequences, and mitigation options. 


EPRI conducted this study with an understanding that obtaining objective data on battery storage fire behavior and mitigation approaches often requires resource-intensive testing – and potentially destruction – of costly equipment. To maximize the value of this research and help avoid duplicative studies, EPRI made the research open to the public. Researchers hope this will help both strengthen new designs and procedures and meet energy storage needs safely and reliably.


The first phase of this collaborative project, Battery Energy Storage Fire Prevention and Mitigation, studied more than 30 failure incidents since 2018 and conducted eight full-site hazard mitigation analyses. Research included site visits, review of publicly available information and official reports, and participation in fire incident investigations. Four themes emerged as likely root causes and principal threats to safe energy storage systems 

 

  1. Internal cell defect. Manufacturing quality control issues introduce unintended distortions, debris, or other contaminants in the cell assembly or chemistry that either induce or, by fatigue, develop into an internal short circuit.  
  2. Faulty battery management system (BMS). Inadequate protection settings or unreliable software or hardware performance result in excursions from nominal operating thresholds (such as voltage, temperature, or duration at a certain state of charge). 
  3. Insufficient electrical isolation. Ground fault, short-circuit, or DC bus power quality that leads to electrical arcing within a module or string. 
  4. Environmental contamination. Exposure to humidity, dust, or otherwise corrosive atmosphere that breaks down existing electrical isolation or insulation.


The research showed that improvement to design and maintenance processes can help mitigate risks for most of these causes, and small changes in the chemical makeup of a battery or the way in which an energy storage system (ESS) container is assembled can have a large impact on the type and magnitude of a safety incident. Read more about the study and lessons learned in the white paper here. 


With these initial findings in hand, EPRI took the research a step further by focusing on identifying, assessing, and addressing broad battery storage fire safety issues. EPRI combined research from our initial study with insights from industry workshops and data from site surveys. The results led to 22 topics of industry need, which EPRI outlined in its Battery Storage Fire Safety Roadmap. 


The roadmap includes topics that will not only improve safety, but also increase system reliability and support the acceleration of this renewable energy option. The 22 topics are categorized into four groups: (1) special topics, (2) response plans, (3) design tools, and (4) technology development. 


Topics were then evaluated on their relative impact on safety, the effort required to address the topic, and the time-horizon for systems the work required. This evaluation allowed researchers to prioritize resources for immediate, near-term, medium-term planning. Of the 22 topics, 10 were identified as research priorities for future EPRI work. The remaining 12 topics that are not included in the EPRI roadmap remain relevant to energy battery storage safety and would be beneficial if pursued by other organizations, such as vendors, OEMs, U.S. Department of Energy national labs, or other entities. 


Topics identified on the roadmap as immediate actions offer high impact with low effort on existing systems. Actions intended to help protect people and property can be addressed with relatively little effort. The impact of these changes will benefit future installations and applications for all stakeholders. 


The near-term actions represent high impact through moderate effort for systems in development. These efforts can be completed relatively quickly and address well-known issues, and results will improve the safety of many systems installed in the near term. 


And, finally, topics identified as medium-term actions provide system design and research guidance for future systems. This work not only creates direct value by providing tools to the industry, but also presents the opportunity to be used to identifying future safety research directions. 


EPRI’s Battery Storage Fire Safety Roadmap will guide future research and build upon these important issues. The institute will soon expand its Battery Energy Storage Fire Prevention and Mitigation research into a larger and more comprehensive second phase. 


During this subsequent research phase, Battery Energy Storage Fire Prevention and Mitigation: Phase II, EPRI aims to provide utilities guidance and tools to support the safety and availability of mission critical grid resources when procuring assets and services, and operating energy storage cost-effectively with environmental responsibility in mind. Researchers will produce an Energy Storage Project Lifecycle Safety Toolkit with guidance on: 

  • Standard compliance testing and safe operation,
  • Safety cost tradeoff determination,
  • Environmental impact assessments, 
  • Community and first responder outreach and educational training materials, 
  • Augmented reality-based training tools, and 
  • Sensor efficacy. 

In addition, EPRI launched the Battery Energy Storage Safety Failure Event Database. This new resource provides a repository of public information for utility-scale energy storage system failure and fire events. The database is designed to crowdsource event information from the industry and available for public review through the wiki format. The database is available now and can be bookmarked here. 


Initial battery fire prevention research demonstrates that battery safety touches all aspects of the ecosystem and is a topic of immediate and reinforced action. From cell suppliers to module and rack suppliers; suppression suppliers to systems integrators; operators, regulators, and even first responders, all have a role to play ensuring battery safety.
EPRI will continue to serve as a connector for these diverse parties, while remaining on the forefront of this research to identify pathways where energy storage can be deployed safely and effectively for the public, operators, and the environment.


To learn more about EPRI’s ongoing fire safety research, visit the Energy Storage program page on EPRI.com. 
 
 
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