Battery unit fire during commissioning at Bouldercombe Battery Project, Rockhampton

In September 2023, during the final stages of commissioning at the Bouldercombe Battery Project near Rockhampton, Queensland, Australia, operated by Genex Power, one of 40 containerised battery units caught fire in the early evening, near the end of a discharge cycle. Site personnel disconnected the facility from the grid. The fire was contained to the single affected unit and did not spread to others, although the immediately adjacent unit was reported to have suffered minor thermal damage to electrical insulation. Local fire and emergency services attended and, consistent with the guidance for this unit type, no water was applied directly to the burning cells. Nearby residents were advised to keep windows and doors closed during the response. There were no injuries. The damaged unit was later transported to a testing facility for detailed physical inspection. The commissioning programme was delayed by approximately six weeks while two replacement units were sourced and installed.

As publicly disclosed by Genex Power around six weeks after the event, a preliminary root cause analysis by Tesla, the battery manufacturer, working with Genex Power and other stakeholders, found that the fault began on the AC side of the affected unit, at the power electronics interface with the AC bus bar inside that unit, and then propagated to the battery modules, leading to the fire. Genex Power stated that the failure was isolated to the power electronics interface in the individual unit and was not considered characteristic of the wider installation. Stated mitigation actions were: replacement of two identified power electronics units, physical inspection of the power electronics in the remaining units at the site, replacement of the two damaged battery units, and an upgrade by Genex Power of breaker control setting response times.

Lessons drawn from the publicly disclosed root cause and response:

1. treat AC side power electronics, including inverter, transformer and bus bar connections, as a primary ignition source in the safety case, not only as a downstream consequence of cell failure;
2. review protection and breaker control response settings for commissioning conditions, including operation near full capacity and end of discharge, rather than assuming steady state settings are sufficient;
3. where a unit level fault is identified, inspect the equivalent equipment in all remaining units on site even when the event is characterised as isolated;
4. confirm before energisation that responding fire and emergency services hold the agreed suppression approach for the installed unit type, including where water is not to be applied directly to burning cells;
5. verify inter unit spacing and containment assumptions against observed outcomes, in this case the fire was limited to one unit of 40 with minor secondary thermal damage to the neighbouring unit;
6. allow programme contingency for sourcing and installing replacement units, which in this case added approximately six weeks to commissioning;
7. publish the preliminary root cause and the corrective actions, including the failed component pathway, so that other operators of similar equipment can act on the same findings.

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