Process simulation-based life cycle assessment of the six-step Cu-Cl Cycle of green hydrogen generation and comparative analysis with other Cu-Cl cycles

PurposeThis cradle-to-gate LCA study aims to examine the environmental burdens of the six-step thermochemical Cu-Cl cycle developed as the ICT-OEC process for producing green hydrogen and compare it with other nuclear-based Cu-Cl cycles, viz. three-, four-, and five-step Cu-Cl cycles.MethodThe focus of the present work was on performing simulations using Aspen Plus and comparing theoretical data with simulated ones, along with its life cycle assessment using GaBi 8 of the six-step thermochemical Cu-Cl cycle, which evaluates the impacts using the CML 2001 method. As the environmental profiles of the system rely entirely on the nature of the energy provided, different sources of energy, such as photovoltaic systems, solar thermal energy, nuclear energy, and hydropower, were explored to achieve H-2 production by the ICT-OEC Cu-Cl cycle. The six-step Cu-Cl cycle was later compared with other nuclear-based three-, four-, and five-step Cu-Cl cycles.ResultsThe electricity grid mix greatly influenced the environmental load of the six-step ICT-OEC Cu-Cl cycle. It was found that the GWP value of the electrical grid was as high as 86.1 kg CO2 eq. for 1 kg H-2 produced by the ICT-OEC Cu-Cl cycle. The results showed lower environmental impacts when electric power was provided from nuclear energy (0.37 kg CO2 eq.). Later, after comparing the results of the nuclear-based six-step cycle with other Cu-Cl cycles, the four-step Cu-Cl cycle showed less environmental burdens due to its lesser energy requirements. The simulations were performed using Aspen Plus for the H-2 system, and the LCA outcomes were successfully validated to the LCA findings acquired by theoretical calculations.ConclusionsThe energy source plays a very pivotal role in the impacts on the environment for hydrogen production. As the present study is part of research and development, it will directly improve the processes in the domain, such as the nature of energy for the production, which will help to reduce the environmental burdens in the whole life cycle of the hydrogen production plant.

Automated summary

This study aims to evaluate the environmental burdens of the six-step thermochemical Cu-Cl cycle for green hydrogen production and compare it with other nuclear-based Cu-Cl cycles. Simulations using Aspen Plus and life cycle assessment using GaBi 8 were conducted to explore the impacts of different energy sources on the ICT-OEC Cu-Cl cycle. The results highlight the significant role of energy source in hydrogen production's environmental impacts.