Battery Energy Storage Systems (BESS) are rapidly becoming a critical part of the energy transition. As renewable generation continues to grow, energy storage plays an increasingly important role in ensuring grid stability, managing peak demand and improving energy reliability.

Alongside this growth has come greater awareness of the hazards associated with BESS installations. Industry attention has largely focused on thermal runaway events, battery fires and the challenges faced by emergency responders when incidents occur. While these discussions are important, they often focus on managing consequences after a facility has already been designed and constructed.

The reality is that many of the most effective safety controls available to a BESS project are established long before the first battery container arrives on site. Decisions made during concept selection, layout development and detailed design can have a significant influence on the overall risk profile of the facility throughout its operating life.

For developers, owners and operators, this raises an important question:

Are we identifying and managing BESS risks early enough in the project lifecycle?

Understanding the Risks Associated with BESS

Modern BESS installations offer significant benefits, but they also introduce hazards that differ from many traditional electrical systems.

One of the most widely discussed hazards is thermal runaway, where a battery cell undergoes an uncontrolled increase in temperature. Once initiated, thermal runaway can generate intense heat and lead to the release of flammable and toxic gases.

Depending on the battery chemistry, design and environmental conditions, this can potentially result in:

• Fire within battery modules or containers.
• Propagation of thermal runaway to adjacent cells.
• Release of toxic and flammable gases.
• Vapour cloud ignition.
• Deflagration or explosion events.
• Damage to surrounding infrastructure.
• Risks to emergency responders and nearby communities.

While improvements in battery technology, management systems and fire protection continue to enhance safety, the potential consequences of a loss of control event can still be significant. Understanding these hazards is the first step in developing a safer facility.

The Design Trap

Many BESS projects unintentionally fall into what could be described as the "design trap",  whereby key risk decisions become effectively locked in before formal risk assessment is undertaken. Some examples include:

• Container spacing
  The separation distance between battery units can significantly influence the likelihood of fire escalation and the effectiveness of emergency response.
• Facility layout
  The location of batteries relative to substations, transformers, site boundaries and occupied buildings can have a major impact on consequence severity.
• Ventilation design
  Appropriate ventilation is critical for preventing the accumulation of potentially flammable gases following a battery failure.
• Emergency access arrangements
  Access routes that seem adequate during design may prove challenging for emergency services during an incident.
• Detection and protection systems
  Early decisions regarding monitoring, gas detection and fire suppression philosophies can significantly influence overall risk reduction.
• Isolation strategy
  Stored Energy is much harder to manage than a simple breaker on the incomer; the energy source is always there. Emergency shutdown and electrical isolation arrangements are far easier to optimise during design than after commissioning.
• Storage of Spares
  When batteries are operational, there is plenty of condition monitoring in place, but how do you monitor the condition of the spare batteries in the store?

Once equipment has been procured, foundations constructed and layouts approved, opportunities for meaningful risk reduction become more limited and significantly more expensive.

This online Safety in Design Training Course is to train the course participants to actively participate in SiD workshops.	Find out about our upcoming Demonstrating SFARP/SFAIRP Training Course	Safety Solutions can model your fire, explosion, and toxic release events with Consequence Modelling.

Why Early Risk Assessment Delivers More Value

The greatest opportunity to influence safety often exists during the design stages of project development.

This is where structured risk studies can provide valuable insights into hazards, failure scenarios and potential control measures before major design decisions become fixed. An effective risk management program may include:

HAZID

Hazard Identification (HAZID) workshops provide a structured process for identifying credible hazards associated with a proposed BESS facility, including electrical, operational, emergency response risks as well as the broader site hazards.

Electrical HAZOP

Electrical HAZOP studies examine how deviations from intended operation could occur and what consequences may result. These studies help teams identify weaknesses in protection systems, operating philosophies and design assumptions before installation.

Bowtie Analysis

Bowtie assessments provide a visual representation of how major unwanted events, such as thermal runaway, can occur and the preventative and mitigative controls in place to manage them.

This approach helps stakeholders understand not only what controls exist, but also why they are important.

SFAIRP Assessments

Demonstrating that risks have been reduced So Far As Is Reasonably Practicable (SFAIRP) is becoming increasingly important for major energy projects.

SFAIRP assessments provide a structured process for evaluating additional risk reduction measures and demonstrating that safety decisions have been appropriately considered and justified.

Consequence Modelling: Turning "What If?" Into Quantifiable Outcomes

One of the challenges when assessing BESS risk is understanding what an incident could actually look like.

This is where consequence modelling can provide significant value.

Consequence modelling uses recognised engineering methods and specialised software to predict the potential effects of hazardous events before they occur. Rather than relying solely on qualitative judgement, project teams can better understand the potential impact of specific incident scenarios.

For BESS facilities, consequence modelling may be used to assess:

• Thermal runaway events.
• Flammable gas release and dispersion.
• Vapour cloud ignition scenarios.
• Explosion overpressure impacts.
• Thermal radiation from fires.
• Escalation effects on adjacent equipment.
• Potential impacts on nearby occupied buildings.
• Emergency response planning requirements.

The results can provide a much clearer understanding of potential consequences and support informed design decisions.

For example, a consequence modelling study may help answer questions such as:

• Is the proposed separation distance between battery containers adequate?
• Could an explosion impact nearby switchrooms or substations?
• Are occupied buildings sufficiently separated from potential hazard areas?
• What emergency exclusion zones may be required?
• Would an alternative layout provide a significant risk reduction benefit?

Rather than being viewed as a compliance exercise, consequence modelling can be a practical design tool that helps developers optimise facility layouts, strengthen risk controls and make more informed investment decisions.

Final Thoughts

As BESS deployments continue to grow, so too will expectations around the identification and management of risk.

While battery technologies, detection systems and protection measures continue to evolve, one principle remains consistent: the best opportunities to improve safety occur during design.

By incorporating structured hazard and risk assessments such as Electrical HAZID, Electrical HAZOP, Bowtie Analysis, consequence modelling and SFAIRP assessments early in the project lifecycle, developers and operators can make better-informed decisions when changes are still practical, effective and cost-efficient.

Because when it comes to BESS safety, the most valuable controls are often the ones designed in from the beginning.

If you would like to discuss how Safety Solutions can assist with risk assessments, consequence modelling or safety studies for your project, please contact our team or explore the links below for more information.

• Find out more about what our Safety in Design Training Course covers.

• Contact us today to discuss Safety in Design Facilitation Service for your operations.
• Strengthen your management system through our Safety Management System (SMS) Audit Service.
• Understand the scale of major incidents with our Consequence Modelling Services.
  
• Or get in touch with our process safety consultants to discuss your facility risks and training needs.