Inherent hazards, poor reporting and limited learning in the solid biomass energy sector: A case study of a wheel loader igniting wood dust, leading to fatal explosion at wood pellet manufacturer

Abstract

Large loaders are commonly used when handling solid biomass fuels. A preventable accident took place in 2010, where the malfunction of a front-end wheel loader led to a dust explosion which killed the driver and destroyed the building. The case offers an opportunity to examine the hazards of solid biomass, the accident investigation and any learning that subsequently took place. The paper argues that learning opportunities were missed repeatedly. Significant root causes were not identified; principles of inherent safety in design were ignored; the hazardous area classification was based on flawed reasoning; the ATEX assessment was inadequate as it dealt only with electrical installations, ignoring work operations; and powered industrial trucks had not been recognized as a source of ignition. Perhaps most importantly, guidelines for hazardous area classification for combustible dust are insufficiently developed and give ample room for potentially erroneous subjective individual judgment. It is a contributing factor that combustible dust, although with great hazard potential, is not classified as a dangerous substance. Accidents therefore fall outside the scope of systems designed to disseminate lessons learned and prevent future accidents. More attention to safety is needed for the renewable energy and environmentally friendly biomass pellet industry also to become sustainable from a worker safety perspective.

Fatal Accidents During Marine Transport of Wood Pellets Due to Off-Gassing: Experiences from Denmark

“…The accident was investigated as a criminal case and the legal system is so designed that findings are kept confidential and out of reach of safety professionals and the general public. This approach has been criticized at an earlier occasion as being entirely misplaced in an accident prevention context [4]. It is a systemic deficiency by design-the bureaucratic judiciary system did not malfunction, it worked precisely as intended.…”

“…Small pieces of smouldering material are difficult to detect and they may migrate in the band conveyor systems and start smouldering fires in the storage areas which may develop into massive storage fires. Smouldering fires are furthermore notorious for their capacity to generate flammable pyrolysis gasses that travel and accumulate, leading to flash fires or explosion hazards elsewhere in the system [4].…”

Solid Biomass Climate Change Interventions Examined in a Context of Inherent Safety, Media Shifting, and Emerging Risks

“…The facility experienced another serious explosion in 2002, which destroyed the same storage building but resulted in no human casualties. Hedlund et al (2014) argue that the case offers a text book example of the truism that if accidents are not investigated, and root causes not identified, they recur. Had the company chosen to rebuild the facility in 2010, which this time they did not, a future repeat explosion would be likely.…”

“…Mitigation seeks to reduce the seriousness of the consequences, i.e., injuries and damage to the environment or property. Inherent safety is seen as a key accident prevention strategy (Ashford 1997;Zwetsloot and Ashford 2003;Ashford 2012;Hedlund et al 2014). …”

Explosion characteristics of pulverised torrefied and raw Norway spruce (Picea abies) and Southern pine (Pinus palustris) in comparison to bituminous coal

“…Fine powders can also be created when handling these fuels, during pelletising, or unloading (10,11). Powders can pose an explosion hazard and the ATEX and DSEAR regulations (12,13) are in place to reduce the risk of loss of property and personnel due to hazardous materials.…”