A Focus on Battery Energy Storage Safety

A Focus on Battery Energy Storage Safety

A Focus on Battery Energy Storage Safety

The fundamental reason for a big upswing in investments and deployments of energy storage is clear. As the global electricity mix adds large amounts of generation from variable sources like wind and solar, battery energy storage is crucial to reliably deliver electrons when the sun is not shining, and the wind isn’t blowing.

As battery energy storage grows in scale and importance, the need to ensure that these systems are designed, installed, and operated in as safe and environmentally responsible a manner as possible also increases. As battery storage systems today overwhelmingly utilize lithium-ion technology, the industry must take steps to prevent and mitigate potential fires and prepare effective responses for the rare instances when they occur. 

Battery storage systems in India today use lithium-ion technology, the industry must take steps to prevent and mitigate potential fires and prepare effective responses for the rare instances when they occur. Taking steps to prevent thermal runaways can reduce but never fully eliminate the potential of its occurrence. 

Understanding Thermal Runaway 

At the most basic level, a thermal runaway in a lithium-ion battery occurs when a failure of some type leads to overheating inside the battery cell. It refers to the decomposing of electrochemistry that generates heat and creates a self-accelerating reaction. Research suggests that there are four root causes of thermal runaway – internal cell defects; faulty battery management systems, including bad hardware or software; insufficient electrical isolation; and environmental contamination from things like humidity and dust.  

Safety Evaluations are Influenced by Subjectivity

There is a fundamental difference between evaluating a battery system to understand its performance and failure modes and conducting a safety evaluation. Performance and safety vulnerabilities can be analysed objectively using quantifiable data. By contrast, safety evaluations are inherently subjective, guided by factors such as the evaluator’s experience and expertise, the system owner’s tolerance for risk, and the interpretation of safety-related data. 

The roles of those assessing safety also influence their perspective and priorities. For example, some fire protection professionals are experienced in hazardous material fires, while others have specific experience with safety events involving lithium-ion or other battery storage chemistries. To maximize safety, it is important to match the expertise and experience of those completing safety evaluations with the system design and technology at individual sites. Doing so also reduces the time required for an evaluation because the experts involved are already familiar with potential safety vulnerabilities and the possibility of missing risks. 

Ownership Models determine Safety Management and Responsibilities

Clear lines of responsibility enhance the safety of battery energy storage systems. In assessing multiple storage system sites, however, EPRI observed that differing ownership models cloud safety management responsibilities. Adding to the confusion, large battery systems are often operated by a mixture of vendors and owners, which can blur responsibility for taking steps to mitigate safety risks. Clearly understanding and communicating safety roles and responsibilities are essential to improving safety. 

Common Safety Data support a Common Evaluation Process 

The optimal approach to assess the safety risks of a battery energy storage system depends on its chemical makeup and container. It also relies on testing each level of integration, from the cell to the entire system. In addition, it’s important to apply the appropriate safety testing approach and model to each battery system. For example, one of the EPRI assessments determined that an incorrect data set was used in safety testing; the data used represented a different battery module than the one to be installed at a site. When the proper data were used, new explosion risks were found, which necessitated a redesign of the battery enclosures. 

Planning for Failure requires Decisions about Acceptable levels of Damage

It is impossible to completely eliminate the risk of a battery system fire. Steps to mitigate the chance of a fire or explosion inevitably involve choices and trade-offs. A recent EPRI study looked at the cost of safety design features in relation to a system’s total cost of ownership. Some owners may accept the possible failure of a system and its components as well as the costs of cleanup necessary after an event rather than bearing the expense of additional safety measures. Others may decide that the possible loss of storage capacity and the expense of cleanup compel greater investments in mitigation and prevention.

Responding to Fires and Other Safety-Related Events 

Open communication during the storage system design phase—Close collaboration and communication between first responders and battery energy storage owners and operators is always important. It should begin well before the installation of the system begins. Often, it only starts during the permitting process, when designs and plans for construction may already be complete. 

This is a lost opportunity. When dialogue begins earlier, first responders can provide input about the most effective fire suppression and containment systems as well as direction on the ideal distance between battery systems to avoid the propagation of fire to other units and containers. First responders can also educate utilities about their typical response protocols. This information can then be integrated into incident response systems. Other guidance covers the development of utility expertise on battery safety and the completion of a comprehensive safety evaluation at each storage system facility. Another important leading practice is for utilities to identify a safety lead at each battery site. This gives first responders a knowledgeable contact to communicate with if an incident occurs. 

Smart Design and an Emergency Response Plan

Firefighters need reliable access to water. Other design features to consider include the presence of multiple alarm systems in case one fails; limits on charging and discharging levels as well as well-defined temperature and voltage ranges; and clear signage showing the location of emergency disconnect switches. Additionally, an emergency response plan that details the procedures for shutting down the battery storage system avoids confusion and risky delays in response.

Collaboration with and Help Training First Responders

Firefighters need to be aware of the design of a battery storage system and the layout and fire protection systems in the facility where it’s installed. The owners and operators of battery energy storage systems should proactively ensure that first responders have that information and should actively solicit their feedback. Storage owners should also make battery storage experts available to first responders and provide ongoing training to help ensure they are prepared in case of an incident.

The main takeaway from the engagement with utilities, first responders, and the owners and operators of storage systems is to be proactively and continuously collaborative.

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