Explosion at Onida ethanol plan ruled accident

November 17, 2023

ONIDA, S.D.–State officials released more details about the cause of an explosion at the Ringneck Energy ethanol plant in Onida.

A report from the South Dakota Department of Public Safety revealed the July incident had been deemed accidental, but investigators said human involvement appeared to be a factor.

The report also highlighted two separate explosions in different areas of the facility that were caused when high-proof ethanol vapors escaped a slurry tank and ignited during a restart process from shutting down operations.

The ignition source at both locations remains undetermined.