A case study on bio-oil extraction from spent coffee grounds using fast pyrolysis in a fluidized bed reactor

The increasing utilization of non-renewable energy resources contributes to the rise in greenhouse gas emissions, leading to a growing focus on renewable resources as viable alternatives for energy production. Biomass, being a sustainable and feasible source, offers a promising solution for clean energy generation. Due to its cost-effectiveness, pyrolysis is appealing as it produces bio-oil, bio-char, and syngas. This study investigated bio-oil production using spent coffee grounds as the feedstock in a fluidized bed reactor, varying the reaction temperature and residence times. Different pyrolysis temperatures' effect on the bio-char and bio-oil yields and energy content were analyzed. The results show that higher temperatures lead to higher bio-oil yields, lower bio-char yields, and shorter residence times. The highest bio-oil yield and energy content can be produced at 500 °C. The bio-oil obtained from the spent coffee grounds has a density of 0.991 g/cm3, a viscosity of 52 cP, and a higher heating value of 41 MJ/kg. Therefore, the spent coffee grounds are a suitable feedstock for bio-oil production for sustainability.