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Safety management is a fundamental feature of all lithium-ion energy storage systems. Safety incidents are, on the whole, extremely rare due to the incorporation of prevention, protection and mitigation measures in the design and operation of storage systems.
5.1 Fire risk
A common concern raised by some communities living close to sites identified for battery energy storage systems is around the risk of fire.
In this section we will outline how this threat is guarded against but first it is important to understand where the risk of a fire comes from.
In the absence of the proper prevention and protection measures outlined below a battery cell can become overheated. This can happen for reasons that could be mechanical (such as impact or vibration), thermal (such as exposure to high heat or inadequate ventilation) and electrical (where the battery cell is overcharged due to improper management).
Any of these could lead to what is known as a ‘cell failure’. If temperature increases at a faster rate than it can be dissipated then this can cause the cell to start to break down, which causes a reaction due to the chemical components of the batteries, that leads to self-heating. This is known as thermal runaway and, if no action is taken to prevent this, it can lead to a fire and the release of toxic or flammable gases such as carbon dioxide or hydrogen fluoride inside the container.
When multiple cells are present there is a risk that an individual overheating cell or cell fire can start to impact its neighbours leading to a cascade effect as more and more cells overheat.
The design of battery storage systems is extremely important in this regard as the goal is to prevent a single cell failure from spreading to others and to contain and reduce the chances of thermal runaway occurring in multiple cells.
The following sections will explain how this is achieved.
5.2 Safety Standards & Testing
There are numerous international standards that ensure that safety is incorporated in the design, manufacture and transportation of batteries in order to minimise the occurrence of defects which could result in a potential hazard.
The International Electrotechnical Commission (IEC), which develops international standards for all electrical, electronics and related technologies, including batteries, has a range of safety standards for testing and certification of lithium ion batteries and storage systems:
• Battery cells certified to UL1642 and IEC62619 (Safety requirements for secondary lithium cells and batteries, for use in industrial applications);
• IEC 62620 (Secondary cells and batteries containing alkaline or other non-acid electrolytes - Secondary lithium cells and batteries for use in industrial applications);
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