Battery energy storage system (BESS) users must understand this risk and the steps they can take to reduce it.
FREMONT, CA: Energy storage and rechargeable batteries are essential to unlocking the capacity of renewable energy. Lithium-ion batteries are already aiding the integration of renewable energy supplies into the grid. However, this is a swiftly evolving field, and as with all developing technologies, some trends and pitfalls are starting to emerge.
One risk is fires caused by thermal runaways, which are causing substantial losses in the industry and a devastating loss of life in some cases. Battery energy storage system (BESS) users must understand this risk and the steps they can take to reduce it.
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What is thermal runaway?
Batteries have long been a large part of our lives and now power several items used in our daily lives, like our cars, laptops, and mobile devices. However, these small-scale batteries (for Ex. Ni-Cad and Li-ion batteries) are fairly strong and have limited power and duration.
BESS are batteries utilized on a much larger scale, with sufficient power and capacity to provide meaningful storage for electric grids. A BESS can be a standalone system near transmission infrastructure or integrated into renewable energy sources or other power generation facilities. BESS projects are also utilized as a power storage solution for remote areas of the country that are not affiliated with a power grid.
Whenever a huge amount of energy is stored — whether in traditional liquid/gas forms or batteries — there is a chance that an uncontrolled release of the energy could outcome in a fire or explosion. In batteries, thermal runaway explains a chain reaction in which a damaged battery starts to release energy in the form of heat, causing further damage and a feedback loop that outcomes in rapid heating.
Left unchecked, the heat produced can cause a fire. Therefore, the only solution to stop thermal runaway is fast cooling the affected cell(s). Otherwise, the affected battery module can be separated so that the reaction is permitted to reach its harmful conclusion in a safe location.
Even though fire is suppressed, thermal runaway alone can generate enough heat to adjacent damaged cells and propagate the reaction. Therefore, thermal management, fire suppression, and physical design layout to isolate batteries from each other are all vital elements to protect a BESS installation from a thermal runaway event in a single cell.
Large-scale battery fires have happened in almost every jurisdiction with BESS deployments over the last few years. For instance, South Korea suffered several destructive fire events between 2017 and 2019, which caused a government investigation and orders to close some units and restrict the charge rates of other BESS installations nationwide.
Even though these changes, other fire events have occurred in South Korea. Extra fires in Europe and North America have highlighted that this failure mode is not special to a specific manufacturer or design — it's inherent in the technology.
It has been noted that the majority of fires are caused by:
- Temperature control.
- Inherent cell defects.
- Damage during construction.
- Operation of the BESS outside of specified parameters (for instance, temperature, charge rate, and state of charge).
- Damage because of operational negligence.
Proactively managing risks
It is obvious from the number and frequency of incidents that thermal runaway and battery fires are serious risks that must be proactively managed by BESS systems' owners, operators, and constructors. Therefore, a holistic approach to BESS design is necessary for each project.
Batteries must be shielded from day one of construction, and there must be a zero-tolerance method for battery abuse. Battery management systems must be refined, monitored, and answered to. Gas detection, explosion prevention, fire detection, fire suppression, and a robust emergency response plan are essential to mitigating damage if a thermal runaway event occurs.
Several new and recently revised industry standards are relevant to the design and deployment of BESS systems. However, technology and industry continue developing rapidly and constantly innovating to enhance project value and safety.
We consider that standards will continue to evolve in response to learnings from events and a greater understanding of what failure means in the industry. As the industry remain to develop, insurers will look more positively on BESS projects that are built following the latest standards.
While future-proofing an installation to guarantee long-term insurability can be challenging in this environment, success can be found in a holistic method that covers all design aspects. For example, a recent Marsh survey determined that insurers of BESS facilities were most interested in the fire protection features, pursued closely by space separation between battery enclosures.
To assess emergency response, underwriters look for proof of detailed dialogue with emergency services and a written protocol for incidents — for instance, documented pre-fire plans. Early engagement with your risk adviser is essential to ensuring that your project is well-protected, safe, reliable, and positioned to advantage from a competitive insurance placement for the long-term life of a project.