Handle with care: safeguarding the use of batteries for energy storage

As the UK continues its transition from fossil fuels to renewable energy sources, the large scale energy storage adoption ahead is evident. Lithium-ion (li-ion) batteries have a crucial role to play, and managing their unique fire risks is key.  

James Mountain, Sales and Marketing Director, Fire Shield Systems, explores the existing regulation surrounding battery manufacture, storage, transportation, installation and use, looking closely at the implications of the wide-scale adoption for building design, fire protection and suppression.

The ongoing shift towards sustainable energy sources has caused an increased reliance on battery energy storage systems (BESSs). These systems are designed to smooth out the energy supply from renewable sources, such that when power input is low, output remains consistent, for example, storing solar energy for night use. However, this can mean the BESS holds large quantities of energy for long periods of time, which presents a number of fire risks requiring tailored solutions.

The risks for BESSs

  • Thermal runaway

Many BESSs include li-ion batteries, as they are well suited to the application, as a result of their high energy density and ability to fully discharge, without impacting the battery’s longevity. This means thermal runaway is a key risk. This is where internal battery defects, mechanical failures/damage or overvoltage in li-ion batteries results in excess heat, which creates more heat. This causes extremely high temperatures, build up of toxic gasses and potential rupture of the battery cells, resulting in fire or even explosion. Without disconnection or rapid control, thermal runaway can spread between cells, self-propagating the fire.

Once a battery enters thermal runaway, it is often very intense and challenging to control. It can take days or weeks to fully extinguish, and residual energy can cause electric shocks even once the fire is put out. As a result, if a battery enters this state, it is often contained and left to burn out naturally, frequently causing whole system loss.

  • Failure of control systems

Failure in the BESS control systems can result in overheating, which leads to increased fire risk if not controlled properly.

  • Hydrogen evolution

For lead-acid batteries, where suitable ventilation methods are not in place, excess hydrogen can increase the risk of fires and explosion for the BESS.

As BESS are starting to be rapidly adopted across a wide range of industries and buildings, managing these risks is increasingly difficult – and many buyers are not aware of the potential hazards and dangers of the systems. Similarly, site selection for the storage is often based on availability of space, instead of taking into account wider considerations on how to control and manage the risks effectively. It’s essential that buyers understand their system’s individual requirements, follow manufacturer guidance closely and consult expertise where necessary.

Safety first

There are several international safety standards for energy storage systems, as well as large format li-ion batteries, with many different organisations leading the work to develop design, testing and installation requirements. One of the key standards arising from this work is the National Fire Protection Association’s standard for the installation of energy storage systems.

The UK’s existing guidance for BESSs covers a range of regulations and requirements surrounding electrical installation, product safety, grid connectivity and dangerous goods.

Reducing the risk

Despite the presence of legislation surrounding BESS fire safety, it can be difficult to determine how to mitigate associated fire risks for individual applications. This can be broken down into three categories:

  1. System design

The material of the BESS is important when trying to reduce associated risks. For example, where possible, the container insulation should be made using non-combustible materials, and the system should include suitable ventilation to minimise the risk of overheating.

  • Site consideration

The site of the BESS – including its design and overall location – should also be considered when looking to minimise fire risk. Battery containers and other major equipment, such as transformers, substations and inverters, should be fully separated where possible, or divided using fire walls where there isn’t sufficient space. 

  • Fire protection systems

Implementing a fire suppression system that is unique to the site’s individual uses and risks is key to ensuring optimum safety when it comes to BESSs. That includes considering:

  • Separation methods
    • Use of dedicated fire areas
    • Type of detection and suppression needed to account for the individual risks
    • Testing of these systems
    • Information for fire fighters, including a planned emergency response.

As the cost of BESSs becomes more affordable, and their adoption more widespread, it is essential we recognise how attention to detail will shape both the future performance and reliability of the systems, but also have an important influence on public confidence.

For more information, visit www.fireshieldsystemsltd.co.uk or call 0800 975 5767.