Life cycle assessment of hydrogen production using concentrated photovoltaics, electrolysis and waste heat recovery systems

Kurzfassung

This master's thesis evaluates the environmental performance and potential for carbon reduction of an integrated system that combines: (i) concentrated photovoltaic (CPV) technology, (ii) alkaline electrolysers (AEL), and (iii) thermoelectric generators (TEG) to produce sustainable hydrogen. The system is designed to enhance operational efficiency by converting waste heat from CPV units into additional electricity using TEGs, thereby supporting the electrolysis process. Utilizing a life cycle assessment (LCA) methodology, this study compares the environmental impacts of the CPV-AEL-TEG system with conventional hydrogen production methods, such as steam methane reforming (SMR). The findings from the study suggest a significant environmental benefit associated with the CPV-AEL-TEG concept. The integrated system exhibits a global warming impact (GWI) of 1.551 kg CO2-equivalent per kg of hydrogen produced, which starkly contrasts with the 10-12 kg CO2-equivalent reported for SMR. The majority of the GWI from the system originates from the production and operation of the parabolic trough concentrator used in the CPV setup. In-depth analysis indicates that the system's enhanced efficiency stems not only from the direct conversion of solar energy but also from the strategic utilization of by-product heat, which without the use of TEGs would be lost to the environment. The CPV-AEL-TEG integration aims at not only reducing greenhouse gas emissions but also at improving the total energy conversion efficiency of the hydrogen production process. This study underscores the potential of integrating waste heat recovery and advanced photovoltaic technology to create a more sustainable framework for hydrogen fuel production. LCA results indicate that the CPV-TEG-AEL system significantly reduces GHG emissions, showing a 10.62% decrease in global warming impact (GWI) compared to the CPV-AEL system and drastically lower emissions than the SMR process. In addition, the system demonstrates significant enhancements in various other environmental categories, including acidification, photochemical oxidant formation, and land use. This underscores its promise as a sustainable option for producing green hydrogen.