News Updates
The Hawaii Natural Energy Institute (HNEI) had been conducting research on renewable energy integration into the grid using knallgas bacteria, which generates energy through reactions between hydrogen (H2 ) and oxygen (O2 ). As part of this work, varying mixtures of H2, O2, and carbon dioxide (CO2) were stored in a supply tank at pressures between 37 and 117 psig. Staff held weekly experiment reviews and considered the process safe, as operating pressures remained below the tank’s maximum rating of 140 psig.
On March 15, 2016, the postdoctoral researcher reported a “cracking sound” on an incubation vessel when pressing the On/Off button of the pressure gauge attached. Upon inspection, the petri dishes inside the incubation vessel were found to be scorched and cracked due to uneven mixing leading to deflagrating reaction.
On March 16, 2016, after filling a gas supply tank, the researcher attempted to reconnect it to the bioreactor. When she turned on the pressure gauge, the supply tank exploded causing severe injuries to the researcher, destroyed equipment, and damaged adjacent labs and hallways.
Investigation by the university safety officials and laboratory personnel suggested that the detonation was likely caused by electrostatic charge accumulation due to a lack of grounding. When the installed digital pressure gauge was switched On/Off, it created a corona or brush discharge, igniting the explosive gas mixture.
Important Notes
The investigation revealed lapses in safety, including:
Minor internal rust went unnoticed, and critical components like digital gauges were not evaluated. All pressure systems require routine, documented inspections beyond visual checks.
Standard lab safety checklists missed hazards associated with gas mixing and pressurized vessels. Inspections must be tailored to lab-specific operations and updated as processes evolve. A formal Process Hazard Analysis (PHA) must be conducted, and documented, every time SOPs change, regardless of process size.
The likely ignition source was a digital pressure gauge. All ignition risks must be identified and mitigated through grounding, bonding, intrinsic safety design, and documented procedures for equipment selection and use.
The tank met typical operational pressure ratings but failed due to internal detonation. Equipment design specifications must consider explosion risks, mixture behavior/interactions, and consequences of flammable material confinement, not just structural compliance.
The lab lacked explosion-rated equipment despite housing flammable gas mixtures at significant pressures and concentrations. Accurate hazardous area classification must guide the design of control systems, selection of electrical and instrumentation equipment, and facility zoning.
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On November 5, 2005, at a waste treatment facility located in Rhadereistedt, Germany, a release of H₂S resulted in four fatalities, including a truck driver, operator, and two additional personnel attempting to rescue those directly impacted.
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