Browsing by Author "Muchele, Emily Machuma"

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    Simulation, Optimization, and Economic Analysis of Biohydrogen Production Using Food Wastes from the Hotel Industry in Nairobi City County, Kenya
    (Kenyatta University, 2025-12) Muchele, Emily Machuma
    Disposed food waste produces greenhouse gases e.g., methane and carbon dioxide in landfills, destroying the environment through climate change and global warming. In the hotel industry, the serving-stage foods which include plate wastes (leftovers) and display (buffet) wastes prepared for consumption but never consumed, end up in waste bins that fill the landfills. About 230 kg of food wastes were collected from 21 hotels in Nairobi City County, Kenya, and characterized in the present study. Using characterization data, the study simulated and optimized bio-hydrogen production from food wastes. A numerical simulation model of air gasification of food wastes integrated with syngas conditioning for hydrogen-rich syngas production by use of Aspen Plus was developed. The influence of gasifier temperature, air-to-fuel ratio (A/F), and steam-to-biomass ratio (SBR) on hydrogen flow rate, yield, and syngas composition was studied. The combined effect of temperature, A/F, and SBR was studied using Response Surface Methodology (RSM) to establish the optimal points for maximum hydrogen production. Furthermore, an economic analysis based on the optimum hydrogen yield was computed. The RSM analysis indicated an optimal performance at a temperature of 889.39 oC, A/F of 0.5, and SBR of 2.87 with a corresponding maximum hydrogen yield of 12.99 %. With a positive net present value (NPV) of $8741, a profitability index (PI) of 1.28, and an internal rate of return (IRR) of 20 %, the cost of investment would be recovered in 4.15 years. These economic results may vary significantly due to the advancement of technologies and changing local economies. The accuracy of the proposed model could be enhanced by incorporating hydrogen storage and hydrodynamics in the future. These results suggest that the raw syngas produced could be cleaned up by running through the cleaning chamber that separates various components and harmful impurities like mercury, sulphur, and unconverted carbon. The carbon footprint of hotels can be measured since it is possible to pull out carbon dioxide and either store it underground or use it for methanol or ammonia production. Hotels can embrace waste-to-energy technologies and zero waste systems to avoid to save on energy costs avoid environmental pollution. It is evident from this study that research on integrated biohydrogen production technologies using different wastes can be commercially explored for the hotel industry.