Life cycle assessment of biofuel production from waste date stones using conventional and microwave pyrolysis

Date palm trees play a crucial role in the provision of essential nutrition by producing date fruits and are widely cultivated in Qatar. The processing of date fruits generates substantial quantities of carbon-rich date stone possessing remarkable energy potential. This inherent energy can be harnessed by applying pyrolysis techniques, which facilitate the production of many products with commercial value. Despite being a novice process, microwave (MW) pyrolysis has emerged as a promising avenue for converting biomass waste into eco-friendly biofuels. Nonetheless, the adoption of this new approach necessitates a comprehensive exploration of its ecological implications, warranting a meticulous life-cycle analysis (LCA) to ascertain its environmental footprint. As a result, using GaBi software, this study compares the life-cycle environmental impact of conventional and microwave-aided pyrolysis processes of date stone waste. The study also assesses the techno-economic analysis of the two processes. The physical and thermal analyses of the date stone waste indicated that the biomass is a high-energy source (Net calorific value-15.6 MJ/kg). While the life-cycle assessment indicated that MW pyrolysis has a greater implication on climate change (14.94 % more), ozone depletion (14.29 % more), ionizing radiation (14.36 % more), and photochemical ozone production (14.44 % more) than conventional pyrolysis. This demonstrates that conventional pyrolysis is less harmful to the environment than MW pyrolysis. The techno-economic analysis infers that conventional pyrolysis mode is superior to MW pyrolysis for the valorisation of date stone waste in terms of profitability, financial stability, and overall success.