Battery energy storage systems are critical to the integration and development of clean energy, but require more advanced fire safety protection measures. Steve Kenny, general manager of fire detection business at Honeywell Building Technologies, analyzed and explained why exhaust gas detection is an important line of defense against thermal runaway of batteries.
Wind power facilities, solar farms, microgrids, data centers and telecommunications facilities have at least one thing in common: They rely on battery energy storage systems (BESS) composed of thousands of lithium-ion batteries. Not only are battery storage systems playing a key role in the transition to renewable energy and smarter grids, but they have become a key component of data centers and telecom hubs—both elements that energize the global economy driving force.
According to the survey, the global utility-scale battery energy storage system market is valued at $2.9 billion in 2020 and is expected to grow at a CAGR of 32.8% from 2020 to 2025, reaching $12.1 billion by 2025. That number more than doubles when you include uninterruptible power supplies (UPS) in data and telecom centers, vehicle charging facilities, and other energy storage applications. The total global energy storage market is expected to grow from $7.8 billion in 2020 to $26.8 billion in 2028.
Why are lithium-ion batteries the preferred battery energy storage technology? First, they are relatively inexpensive and provide higher energy density due to their size and weight; they have a longer continuous discharge time; they are less prone to self-discharge than other types of batteries; and require little maintenance , and does not require regular exhaust emissions.
Despite the multiple advantages of lithium-ion batteries, there are also some disadvantages. On the one hand, lithium-ion battery energy storage systems require sophisticated battery management systems (BMS) to maintain operation within safe parameters of voltage, temperature, and charging. If mismanaged or abused, the battery can fail, cause venting or overheating, and if the battery catches fire (thermal runaway), it can quickly escalate into a catastrophic fire, or even an explosion, which is extremely difficult to extinguish and can be extinguished with dominoes The domino effect accelerates diffusion to surrounding batteries.
Three Stages of Battery Failure
• Abuse factor: Electrical abuse, overheating, or mechanical abuse can lead to thermal runaway. Electrical abuse occurs when battery voltage limits are exceeded during charging or discharging. Because a large number of cells in a battery energy storage system are charged or discharged at the same time, the risk of electrical abuse of a single cell increases. Thermal abuse occurs when operating temperatures exceed the battery's endurance limit. Mechanical abuse refers to physical damage such as crushing, indentation or puncture.
•Battery venting (exhaust gas): If the abuse factor continues, the liquid electrolyte in the battery will convert to gas, which will cause the internal pressure of the battery to increase enough to open the pressure relief hole or break the battery seal. This outgassing is distinct from the outgassing after thermal runaway occurs, and typically occurs several minutes before thermal runaway.
• Thermal runaway: As the internal temperature of the battery increases, the separator will melt and rupture, releasing fumes and igniting the electrolyte. Gases emitted during this phase typically include carbon monoxide (CO), carbon dioxide (CO2) and combustible gases. The resulting fire can generate temperatures above 1,000°C and spread to surrounding batteries, causing them to enter a thermal runaway state that can cause the entire system to fail and catch fire.
Challenges brought by battery energy storage systems to traditional monitoring technologies
Battery energy storage systems require a battery management system (BMS) to monitor voltage, current, and temperature and prevent battery abuse, but relying on a battery management system (BMS) as the only layer of defense against thermal runaway is risky. On the one hand, the battery management system (BMS) cannot resolve the temperature or voltage of a single battery. Even with temperature sensors on each battery, there may be undetected hot spots.
Traditional monitoring techniques such as smoke and fire detection, carbon monoxide (CO) monitoring, carbon dioxide (CO2) monitoring, lower explosion limit (LEL) monitoring often form part of a battery energy storage system safety solution. Smoke and fire typically don't occur until thermal runaway begins, so these battery storage systems don't kick in until it's too late to stop the chain reaction. Carbon monoxide (CO), carbon dioxide (CO2), lower explosive limit (LEL) gases are generally not present in detectable concentrations until thermal runaway occurs.
In short, these techniques are passive responses to thermal runaway rather than active prevention. Even if a battery has reached the point of smoking or catching fire, it may be too late to stop its fire from spreading to surrounding batteries.
Initial exhaust (exhaust) detection before thermal runaway
Detecting early signs of lithium-ion battery failure is critical to enabling operators and shutdown measures to respond proactively in a timely manner to prevent thermal runaway and catastrophic (often explosive) fires.
A study by safety agency DNV tested three techniques to assess the response time of lithium-ion batteries in detecting early signs of potential thermal runaway: exhaust gas sensors, battery voltage sensors, and lower explosion limit sensors, which can detect flammable gases or solvent vapors dangerous level.
Of the three types, exhaust gas detectors have the highest sensitivity and accuracy. They had an average response time of less than 10 seconds after the onset of exhaust gas emissions and 6 minutes and 11 seconds before the onset of thermal runaway. Neither the LEL nor the voltage sensor is active until thermal runaway starts.
The findings also show that the shutdown measures combined with exhaust gas detection are effective in preventing thermal runaway. Once exhaust gas is detected, the battery energy storage system automatically shuts down to prevent the battery temperature from rising, thereby preventing thermal runaway from spreading to adjacent cells.
Manly Battery Co.,Ltd specializes in providing energy storage power, UPS backup power, power supply and new energy system solutions and operation and maintenance services for new energy, electric wheels, smart energy storage and green power applications. Among them, the field of network energy mainly includes communications, power, data centers, financial securities, rail transit, etc.; the field of smart energy storage mainly includes household energy storage, industrial and commercial energy storage, and microgrid energy storage systems; the field of green power mainly includes forklifts, low-speed electric vehicles, off-road vehicles, etc. At present, the main products are lithium-ion batteries and systems, lead-acid battery replacement lithium batteries and systems, and new energy system integration products and services. Please contact:
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