On July 29, 2025, three people were killed — a father and his two young daughters who were employees of Horizon Biofuels LLC — in a combustible wood dust explosion at a wood pellet production facility in Fremont, Nebraska. The explosion occurred at a wood pellet production tower where biomass materials including wood dust were processed. The incident is among the most heartbreaking in recent CSB history.

Wood pellet production generates significant quantities of combustible wood dust throughout the process — from grinding and drying through conveying, storage, and pelletizing. Combustible dust explosions in biomass processing facilities have been documented repeatedly over the past two decades, with multiple CSB investigations and OSHA enforcement actions highlighting the hazards. The CSB deployed an investigation team to the Fremont facility.

Preliminary findings are focused on dust accumulation levels in the production tower, explosion isolation and suppression systems, and the adequacy of combustible dust hazard management at the facility. The investigation is examining whether the facility had conducted a dust hazard analysis per NFPA 652 requirements, whether housekeeping requirements were adequate to prevent secondary dust accumulation, and what explosion protection systems were in place.