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Biowaste-to-biogas processes have been introduced to design a valuable and green renewable plant to achieve a sustainable society and environment. The biomethane production process through biogas upgrading instead of designing a combined heat and power (CHP) system can be more attractive. This study presents a life cycle analysis (LCA) from both cost and environmental standpoints for four biowaste-to-biogas/biomethane process scenarios. Biogas production is achieved through anaerobic co-digestion of the organic fraction of municipal solid waste (OF-MSW) and secondary sewage sludge (S-SS), incorporating a pre-treatment process based on the dark co-fermentation process (DCFP). Each scenario offers distinct methods for utilizing the hydrogen-rich gas and biogas, with varying degrees of energy recovery and efficiency. Two sensitivity studies were conducted under various utilizations of the recovered biomethane and the anticipated electricity mix. Scenario SC-1 (CHP-from-biogas) was found to be the most co-friendly favorable in eight out of eleven impact categories (under the CML/IA technique). Further, biogas upgrading-integrated options exhibited lower impacts. Replacing biomethane instead of petrol in scenarios with upgraded biogas was identified as the most effective approach against climate change. Financial analysis indicated that all layouts are economically viable, each demonstrating a positive NPV over a 20-year period (up to $11.57 million). • Life cycle analysis for different biowaste-to-biogas/biomethane scenarios. • Anaerobic co-digestion process of MSW organic fraction and secondary sewage sludge. • Different method for utilizing the hydrogen-rich gas stream and biogas. • Biogas upgrading-integrated options exhibited less impact in the respective items. • Economically viable, all option demonstrating a positive NPV over a 20-year period. [ABSTRACT FROM AUTHOR]

The role of any fuel cell is direct electricity-generation using electrochemical reaction. However, wasted heat is an unavoidable side-product of any fuel cell. Thermoelectric is another electricity generator producing electricity directly from a source of heat. Hence, this is a potential opportunity to recover the waste heat of the fuel cell by thermoelectric generator meaning higher overall performance of the system. This research proposes and optimizes a novel hybrid fuel cell and two-stage thermoelectric generator to catch the mentioned goal of the research. In this hybrid-system, the serpentine channels of the fuel-cell are directly in contact with ceramic layer of a two-stage thermoelectric generator. The proposed configuration is investigated using a validated 3D-finite-element-method. A comprehensive parametric analysis is provided to optimize the system. The results reveal a great performance for the suggested two-stage TEG configuration when the high-temperature skutterudites and low-temperature bismuth tellurides are employed in the high-temperature and the low-temperature stage respectively. The overall-output-power enhances 2.73-fold in the optimized configuration. Increasing the overall thickness enhances output power, with a notable 233 % increase, when h t goes from 1 to 4. A remarkable 209 % growth is shown when the number of thermocouples in the low temperature stage increases from 36 to 144. [Display omitted] • A portable hybrid fuel cell and thermoelectric generator is proposed. • A comprehensive parametric analysis/optimization is provided. • The overall output power enhanced 2.73-fold in the optimized configuration. • Proposed hybrid system was found appropriate for waste heat recovery application. [ABSTRACT FROM AUTHOR]