A chemical process design for green hydrogen production through water electrolysis in Lesotho
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Date
2024
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National University of Lesotho
Abstract
This research addresses the pressing need for process design models that are specifically adapted to Lesotho's distinct resource profile, particularly its vast hydroelectric capacity. At present, there is a noticeable gap in process models designed for green hydrogen production that take into account the unique energy conditions of Lesotho. To address this shortcoming, the study presents a detailed chemical process design for hydrogen production through water electrolysis, utilizing Lesotho’s renewable energy. The process model developed includes detailed mass balances to ensure precise quantification of material flows. Critical process parameters, including molar and mass fractions as well as stream molar flow rates, are defined to accurately describe the system, providing a solution that is specifically optimized for Lesotho's energy resources. The key unit operations, including separators, mixers and an electrolyser, are carefully modelled. Separators are used for phase separation and component purification, while mixers are designed to efficiently combine process streams. The electrolyser, central to the process, is modelled according to the electrochemical reactions which take place and mass transfer considerations. To ensure accurate phase equilibrium calculations, the Rachford-Rice equations are applied. Additional equations are formulated to characterise equipment performance and to address system constraints, such as product purity requirements. The developed model serves as a tool for enhancing hydrogen production and assessing overall process efficiency. It offers a framework for examining how different operating conditions and design parameters affect system performance. Future research should focus on incorporating renewable energy sources like wind and solar to diversify and enhance the sustainability of hydrogen production in Lesotho. Performing comprehensive energy balances will offer deeper insights into the system's efficiency and potential for optimization. Moreover, including economic and environmental assessments will provide a more thorough evaluation of the commercial feasibility of green hydrogen production in the country. These suggestions not only address current gaps but also lay the groundwork for developing a more integrated and scalable model for green hydrogen production, which could be applied to other regions with similar renewable energy resources, supporting both regional and global efforts towards sustainable energy transitions.