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CROSS Safety Report

Battery Energy Storage System concerns

Report ID: 1166 Published: 24 May 2023 Region: CROSS-UK


A reporter informed CROSS about issues that emerged, and had to be resolved, in the design and management of Battery Energy Storage Systems.

Key Learning Outcomes

For designers:

  • Engage early with the Fire and Rescue Service in the design process of Battery Energy Storage Systems
  • A Battery Energy Storage System may not always be a 'common building situation'

For the Fire and Rescue Service:

  • Attempt to provide guidance on the design specifications for Emergency Water Supplies within the appropriate jurisdiction

For operators of Battery Energy Storage Systems:

  • Consider the necessity of producing an Emergency Response Plan for First Responders
  • Review the process of detecting a fire and alarming the emergency services
  • Ensure that safety signage complies with the Electricity, Safety, Quality and Continuity Regulations 2002

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The safety issue reported relates to a Battery Energy Storage System (BESS) which was built and commissioned in 2018.

Due to the drive to decrease reliance on fossil fuels and limit carbon emissions, renewable energy sources are increasingly being used. This increase in renewable energy comes with several challenges, one of which is that often renewable energy is produced when the grid doesn’t require the energy. This means the potential energy being created is either lost or stored for use when the grid requires it. For the latter case, there was a National Grid policy on Enhanced Frequency Response (ERF) which evolved into the Dynamic Containment system. This need for storage means an increase in BESSs to store energy when the demand in the grid increases.

The reporter is of the opinion that the application of Approved Document B (ADB) to meet the functional requirements of Building Regulations is not always sufficient for certain types of buildings, considering that BESSs should be considered as 'complex' situations. They think the technology in relation to BESSs is changing and evolving at a fast pace, and can potentially outpace current fire safety guidance or legislation.

    the application of Approved Document B (ADB) to meet the functional requirements of Building Regulations is not always sufficient for certain types of buildings

    To cater for these cases, the reporter considers it helpful to share some of the lessons learned from the project, so that practitioners can be aware of them and address the issues accordingly should they be encountered. The reporter raised three issues regarding their experience with the installation.

      Emergency Water Supply

      Firstly, a fire hydrant has not been provided within 90m of the site, and this was never picked up on in the consultation with the Fire and Rescue Service (FRS). In this case, that means that the nearest fire hydrant is some 1.7km from the site.

      Furthermore, there is no Emergency Water Supply (EWS) at the site. It has been suggested that attenuation ponds can be used as an EWS but, in the reporter’s opinion, they cannot. This is for the following reasons: the attenuation ponds are seasonal and often there is no water within them, making them an unreliable solution; the attenuation ponds are also not deep enough for a fire appliance to obtain a lift; finally, there is no penstock which means it is not possible to contain water within the pond to provide an adequate depth.

      This is of concern to the reporter, because should a fire situation occur at the BESS it is likely the delay in obtaining an adequate water supply could result in the fire spreading to include other electrical infrastructure. This is because it is accepted in the reporter’s circles that water is the best firefighting medium for the containment of a BESS fire. Large volumes of water could be required should an incident occur, though it should be clarified that this is not to extinguish the fire but to prevent it from spreading to adjacent installations or buildings.


        The other issue raised by the reporter is that signage is often poorly displayed at the BESS. This means a first responder attending an incident may not be able to identify the message of the sign. In this case, the ‘Danger of Death’ signage displayed at the access points is not on a yellow background, only the inner portion of the triangle is yellow. Additionally, the signs have been placed on a brush steel effect background. Operators of BESSs, and FRSs, need to be made aware of the Electricity, Safety, Quality and Continuity Regulations 2002 in which Schedule 1 - Design, Colours and Proportions of the Safety Sign states:

        'The triangle, symbol and text shall be shown in black on a yellow background.'

          Detection and Alarm

          These sites are often remotely monitored – in the reporter's case the site is remotely monitored in another European country. Initially, however, the Automatic Fire Detection would only raise the alarm abroad and the monitoring company was able to summon the local FRS. This has now been resolved by the Automatic Fire Detection system being linked to an Alarm Receiving Centre in the UK. The Alarm Receiving Centre will contact the Centre in the other European country should a signal be transmitted to confirm a fire or false alarm.


            The reporter made several suggestions that could potentially resolve many of the issues recognised in this report:

            • To avoid similar issues from occurring in other BESS installations, it is crucial that the FRS and proposers of BESS to engage early in their design process. For this engagement to be meaningful, the FRS should acknowledge the BESS should initially be seen as a 'complex' situation (hence the application of only ADB rules for such premises not being acceptable to the reporter)
            • Designers of BESSs within the UK should consider the usefulness and appropriateness of any rules found in NFPA 855 – Standard for the Installation of Stationary Energy Storage Systems. In the reporter’s experience, some suppliers, developers and designers have recognised the benefits of applying concepts of NFPA 855 to certain aspects of their design
            • Operators of BESSs need to produce Emergency Response Plans (ERPs) for First Responders (firefighters). The ERPs need to be developed with the design specification of the BESS, but also in collaboration with the FRS that has responsibility for the BESS
            • FRSs in England should provide guidance on the design specifications for EWS within their jurisdiction. This could be similar to the fire appliance access table e.g., the specifications for an above ground EWS to include connections for the FRS to discharge and resupply, a low-level alarm, or trace heating to prevent freezing
            • More guidance is needed on the design specification for a BESS within England, considering that a document like NFPA 855 would be a beneficial tool for designers and reviewers

            Expert Panel Comments

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            The Panel agree that there are significant fire safety concerns related to BESSs. Battery storage is an essential part of society's move towards a zero-carbon future, but it needs to be done in a way that recognises and manages risk.

            Firefighting water supplies

            As identified by the reporter, containment of a fire is likely to require a substantial volume of water. The example given, where a site was created without consideration of a firefighting water supply, may not be an isolated event, as there is no requirement to inform or consult the FRS during the planning stage and this issue is unlikely to be picked up by any other body involved in the project. 

            The Panel identify wider concerns regarding domestic (relatively small) and mid-scale (similar in size and appearance to ISO shipping containers) which are being placed into/on top of/underneath/adjacent to premises. Larger grid-scale systems may be classed as infrastructure and may fall outside of the scope of the Building Regulations. From a UK FRS perspective, this limits the opportunities the UK FRS has to even be made aware of the proposal, let alone to be able to comment.

            this limits the opportunities the UK FRS has to even be made aware of the proposal

            Standards and guidance

            The Panel agree that large-scale BESS are likely to be outside of the scope of ADB, are not a common building situation and are not considered in the scope of other widely accepted fire safety design documents in BS 9999/9991. This then requires that a performance-based design from first principles address the risks required. 

            NFPA 855 (2023 version) is available and has been informed by high profile incidents and learning. Attention is also drawn to the Country Fire Authority's Design Guidelines and Model Requirements for Renewable Energy Facilities (2022)  

            There is a need to provide future guidance on appropriate fire safety provisions for BESSs based on evidence, research and lessons learned from real fire incidents, to assist a fire-engineered performance-based approach solution. 

            Consultation at the planning stage 

            It would clearly be beneficial for early engagement with the FRS to take place but there is no statutory requirement for a consultation with the FRS at the planning stage. Information is required that provides sufficient detail to allow meaningful consideration of the hazards, and to enable an assessment of the suitability of the proposals to manage potential risks. The National Fire Chiefs Council (NFCC) are planning to publish guidance to FRSs on this matter in 2023. 

            It is noted that some FRSs routinely check planning applications in their areas and follow up on the ones that are deemed significant based on the information provided. This is not a statutory duty, the extent of the practice is unknown, but it gives an opportunity for timely advice regarding matters such as water supplies and access, matters that may be more costly and difficult to provide later on in a building project.  

            New developments on greenfield sites will be of particular interest because they will be unlikely to have the water supply and access infrastructure. Planning for new towns or housing estates may cover this, but it is less likely on rural/agricultural sites.

            Lessons learned from international events

            There have been some significant fires involving BESSs, and some training resources and lessons have emerged: 

            • Fire Safety Research Institute modules on Lithium-Ion Batteries and Lithium-Ion BESSs 

            • FSRI report into Surprise, Arizona BESS incident

            • Fisher Engineering, Inc and the Energy Safety Response Group's Victorian Big Battery Fire report into a Tesla Megapack fire in Australia 

            • CTIF (the International Association of Fire and Rescue Services) accident analysis of a Beijing lithium battery explosion which killed two firefighters

            Firefighter safety - consequences of defensive firefighting 

            BESSs clearly pose a risk to firefighters, as evidenced by the incidents listed in this report.  

            Through the FRS information and gathering processes and production of a site-specific risk information (SSRI) record, it is possible that the FRS may adopt a defensive strategy. This could lead, in event of a fire in a BESS, to limiting firefighting to protect surrounding risks and not directly tackle the fire. An uncontrolled fire is likely to lead to the production of toxic and potentially explosive gases entering the environment through the fire plume and contaminated water runoff. Firefighting is challenging when the BESS is in the open air. If it is inside the premises, this introduces further challenges and potential operational decisions that may lead to an uncontrolled fire. 

            This could lead ... to limiting firefighting to protect surrounding risks and not directly tackle the fire

            CROSS-UK report 1058 - Fire safety risks with lithium-ion batteries states:

            ‘…this is not only an isolated sector issue but one that society must address together in good time … This issue is not only of concern to the FRS, but the designers, developers and occupiers of these sites also need to acknowledge the risks and evidence of how these systems can be safely integrated into society.'

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