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Fire Risks at Battery Energy Storage Facilities


4 mins


Naama Munster

published published

July 20, 2021


Application StoryFire Detection

A Burning Concern

Suppressing a battery fire, particular a lithium-ion battery, is no small feat. Success depends on how quickly the Battery Management System (BMS) alerts of a fault and activates countermeasures. Early detection is key. In 2019, a series of failures triggered an explosion at the Arizona Public Service Electric’s McMicken battery energy storage facility. The fire caused injuries to firefighters and the destruction of a grid-scale battery storage system, all of which began with an internal cell defect. Similar incidents have occurred worldwide. Lithium-ion (Li-ion) batteries power the lives of millions every day. This battery technology is growing in popularity, from laptops and cell phones to electric cars, due to its compact size and the ability to store high energy per unit mass and volume. However, what makes them so popular, also makes them dangerous. A Li-ion battery cell consists of an anode, cathode, separator, electrolyte, and two current collectors (+/-). This functional principle has its flaws. The battery cells contain large amounts of chemical energy in a condensed space and only a narrow separator between the electrodes. Also, the electrolytes used are highly flammable. For this reason, it is crucial to monitor the battery temperature. When a battery fails due to overcharging or short-circuiting, the temperature rises and triggers chemical reactions inside the battery in a self-exciting chain reaction called a “Thermal Runaway.” Before reaching a point-of-no-return, it’s crucial to stop a cascade failure.

Battery Storage Farm - Thermal Imaging

The Thermal Runaway Effect

During a Thermal Runaway event, cell temperature may rise hundreds of degrees within milliseconds. The electrolyte evaporates as the cell heats up. The pressure inside increases until the electrolyte vapors expel through a relief valve or burst through the cell wall. A vapor release can result in an explosive gas-air mixture combusting and exploding from the tiniest ignition source. A Thermal Runaway event in a battery system can spread from cell to cell, leading to a major fire, especially in an enclosed space. There are early signs before the actual Thermal Runaway event. Smoke and gas detectors are widely employed in battery management systems and somewhat effectively identify an incipient failure event. Unfortunately, they have not proven reliable for extracting critical real-time data; thus, they fail to provide proper early warning. New detection technologies explicitly designed for Li-ion off-gases are beginning to emerge. However, they are still in the relatively initial stages of production and have not been adopted by the industry. Recent incidents involving battery storage, such as the 23 battery energy storage installations in South Korea during 2018, have led to a noticeable shift towards safety within the industry, which is now looking for reliable detection solutions.

Inserting Thermal Imaging into the Picture

One of the major hurdles in the development of large fleets of electric vehicles continues to revolve around safety issues concerning the use of Li-ion batteries. The main drawbacks posed to this industry are the battery cell’s temperature excursions and non-uniformity. Therefore, heat measurements are essential. Many management systems now employ thermal imaging cameras and calorimetric techniques to obtain a thermal fingerprint of the battery surface. Infrared thermal imaging technology was found to be ideal in getting real-time thermal data. Researchers have found thermal imaging to be a reliable and practical solution to investigate the thermal behavior of Li-ion batteries as a non-invasive measurement tool. They point out the advantages of infrared thermal camera technology compared to Liquid Crystal (LC) Thermography, including a wider temperature range, higher accuracy, and more vivid colors. Minute thermal inhomogeneities are easily detected on the battery using thermal cameras; this allows for the analysis of temperature homogeneity and distribution on the battery surface. Using a thermal camera, the BMS can follow the dynamics of the heat evolution during the discharge and charge processes, thus alerting any abnormalities that might lead to a Thermal Runaway event, allowing the system and operators enough time to activate countermeasures.

Battery Storage Farm - Thermal Imaging

Hotspot Detection

A High Risk of Fire event (often called Hotspot Detection) determines which pixels have exceeded a user-defined temperature threshold. Once set, the fire detection camera, such as Opgal’s Sii AT thermal camera, displays the area exceeding the pre-defined threshold as red pixels, highlighting the problematic region in the video image. A single thermal imaging camera can observe a wide area simultaneously monitoring for hot spots and flames, thus eliminating the need for individual sensors for each power cell. Opgal’s thermal cameras are used around the globe to alert of the risk of fire and dangerous spikes in temperature. They keep an eye out on warehouses, coal depositories, waste management facilities, recycling depots, towns, and more. Highly accurate and extremely sensitive, these thermal infrared cameras can detect minor shifts in temperature, even to the point of estimating the temperature in a moving crowd. Field-proven to be a reliable hotspot detection tool for decades, our line of fire detection cameras for Flame and Hotspot Detection are versatile and suitable for any budget. Opgal has got you covered, from enclosed cameras, big or small, through advanced dual-channel PTZ thermal camera systems overlooking wide areas, and OEM thermal camera solutions widely utilized in the industrial sector, including condition monitoring and thermal inspection of electrical circuits.

Battery Storage Farm - Thermal Imaging