Energy and Exergy Analysis of a Novel Multi-Generation System Based on Biomass Gasification for the Simultaneous Production of Electricity, Fresh Water, Heat, and Hydrogen

Document Type : Original Article

Authors

1 Energy Systems Engineering, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran

2 Department of Mechanical Engineering, Hamedan University of Technology, Hamadan, Iran

Abstract

In this study, an energy and exergy analysis is conducted on a novel and integrated polygeneration system based on biomass gasification. The primary objective of the system is to simultaneously produce electricity, freshwater, hot water, and hydrogen with reduced environmental emissions, utilizing pine sawdust as a biofuel through a gasification process. The system architecture comprised a gasifier, water heater, proton exchange membrane (PEM) electrolyzer, an organic Rankine cycle (ORC) equipped with a recuperator, and a thermal desalination unit. A gas turbine carried out the main electricity generation. The results of the analyses indicated that the system achieved a thermal efficiency of 80% and an exergy efficiency of 42.55%, with the total exergy destruction of 4065 kW. A detailed breakdown of exergy destruction across system components revealed that the gasifier and gas turbine were the dominant contributors, accounting for 48% and 34% of the total exergy loss, respectively. A comparative assessment with similar systems reported in the literature demonstrated that the proposed system exhibits a higher thermal efficiency. Parametric studies further revealed that increasing the working fluid pressure in the ORC up to 5800 kPa reduced exergy destruction in the steam generator, resulting in an increase in the net power output to 3379 kW and an improvement in exergy efficiency to 45.0%. Additionally, raising the inlet air temperature to the combustion chamber to 1300°C enhances the net electrical power output to 3508 kW and increased the overall exergy efficiency to 46.0%.

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