Fire Safety of Onboard Battery Rooms (BESS)
A thermal runaway fire in a battery room does not behave like a conventional engine room fire: the new EMSA guidance on Battery Energy Storage Systems exists precisely to close this operational knowledge gap.
Operational Explanation
Battery Energy Storage Systems (BESS) installed on hybrid or electrically propelled ships are fixed installations distinct from lithium battery cargo carried as freight: these are large battery banks, often installed in dedicated engine room compartments, presenting a specific fire risk profile linked to the phenomenon of thermal runaway, distinct from a conventional fire.
EMSA has published dedicated guidance on the safety of onboard BESS, recognizing the growing complexity of these installations, with high total energy storage and a risk of fire propagation from one cell to another within the battery bank that requires specific response strategies (massive and prolonged cooling, isolation of the affected bank) distinct from conventional extinguishing techniques applied in the engine room.
Regulatory Reference
EMSA guidance on the Safety of BESS on board ships: specific recommendations for installation and emergency response in onboard battery rooms. Complementary industry standards such as NFPA 855 (update expected in 2026) and UL 9540/9540A (revised edition 2025) provide technical references on mitigating energy storage system risks, although developed mainly for land-based applications.
Scope of Application
Every hybrid or electrically propelled ship fitted with onboard battery rooms (BESS), with responsibility on the crew for specific training on responding to a thermal runaway event in these installations.
Procedure / How to Complete It
- Identify the location and specific configuration of onboard battery rooms (BESS), distinguishing them from conventional engine room spaces in the emergency response plan.
- Train the crew on the specific response strategy to thermal runaway in a battery room: massive and prolonged cooling of the affected bank, not conventional extinguishing.
- Verify the availability and operation of detection and alarm systems specific to the battery room, distinct from those of the main engine room.
- Consult the EMSA guidance on the safety of onboard BESS to update response procedures specific to the installed plant configuration.
- Include specific thermal runaway scenarios in the battery room in periodic fire drills, explicitly distinguishing them from conventional engine room fire scenarios.
Practical Example
Example: during a periodic fire drill on a hybrid ship, the crew simulates a thermal runaway event in the battery room, applying the massive cooling and isolation strategy for the affected bank, distinct from the standard procedure used for a conventional engine room fire, according to the EMSA guidance on BESS.
Real Cases
Common Mistakes Mistake Library
| Mistake | Consequence | How to avoid it |
|---|---|---|
| Battery room (BESS) treated in the emergency response plan as a generic extension of the engine room | Inadequate response strategy in the event of a thermal runaway event | Treat the battery room as a specific risk area in the emergency response plan, with dedicated procedures |
| Periodic fire drills that do not include specific thermal runaway scenarios in the battery room | Crew unprepared to apply the massive cooling strategy in a real event | Always include specific thermal runaway scenarios in the battery room in periodic drills |
| EMSA guidance on BESS not consulted when updating onboard operating procedures | Response procedures not aligned with the most up-to-date industry recommendations | Consult and integrate the EMSA guidance in defining battery room-specific operating procedures |
PSC Observations
Operational Tips
- Don't treat the battery room as a simple extension of the engine room: thermal runaway requires a specific response strategy.
- Consult the EMSA guidance on onboard BESS safety to update operating procedures to your installation's specific configuration.
- Always include thermal runaway scenarios in the battery room in periodic fire drills, distinguishing them from conventional scenarios.
Checklist
- Location and configuration of the battery room (BESS) identified in the emergency response plan
- Crew trained on the massive cooling strategy specific to thermal runaway
- Detection and alarm systems specific to the battery room verified as functioning
- EMSA guidance on BESS consulted to update operating procedures
- Thermal runaway scenarios in the battery room included in periodic fire drills