Quantitative Risk Assessment in Thermo-Chemical Waste-to-Energy Facilities

This study presents a Quantitative Risk Assessment (QRA) of thermo-chemical Waste-to-Energy (WtE) technologies, specifically incineration and gasification, by utilising simulation tools PHAST and SAFETI. Hazard identification, consequence analysis, and risk assessment were conducted to compare the safety profiles of these two technologies and proposed risk reduction strategies for a safer design. Accident scenarios were modelled for Tuas South Incineration and Borregaard Gasification facilities to analyse dispersion and effects of fire and explosion. Hazards indicated that only gasification exclusively involves flammable releases because it reacts as a partial combustion, with carbon monoxide and hydrogen as flammable byproducts. Results revealed that while gasification posed lower risks of toxic release, incineration exhibited lower fire and explosion risks. Individual risk fell within the ALARP region for both plants, with societal risk showing incineration falling within ALARP with a total risk integral of 0.000178/AvgYear but gasification nearing the unacceptable region with a total risk integral of 0.000586/AvgYear and a maximum potential average fatality of 8.5 and 24.5, respectively. Therefore, this risk assessment indicated that while both plants posed risks, incineration generally exhibited lower risks than gasification. Risk reduction measures such as leak detection and emergency response plans were recommended. This study enhances understanding of WtE risks, facilitating safety protocol improvements for a safer and sustainable WtE operation.