Gate-to-gate life cycle analysis of a pilot-scale solar driven two-step thermochemical hydrogen sulfide decomposition for hydrogen production

Abstract

Hydrogen is one of the most viable options towards decarbonization. It is crucial to upscale the hydrogen economy considering the current state of the environment due to the adverse effects of climate change. In this study, a gate-to-gate Life cycle assessment (LCA) was conducted on a hydrogen sulfide splitting model that replicates a pilot-scale plant by integrating the two-step solar thermochemical H2S decomposition using SimaPro version 9.4.0 software. This analysis starts from the treatment of H2S gas released by the refineries as waste and ends at the production and storage stage of hydrogen. There are two functional units used in this study which are ‘1 kg of H2’ to assess the operational phase of the simulation plant and ‘1 unit of H2S splitting plant’ to determine the environmental performance of the construction of the plant. The top three most impacted midpoint level categories in the operational phase are human carcinogenic toxicity (HTP), freshwater ecotoxicity and marine ecotoxicity with an amount of 3.66 × 10−4, 1.10 × 10−4, and 1.40 × 10−4 kg 1,4-DCB respectively. Electricity has a higher relative contribution to this technology due to the high amount of steel used during the construction of solar tower. Meanwhile, treating H2S leaves a positive impact towards every midpoint indicator, mainly on terrestrial acidification, fine particulate matter formation and ionizing radiation. The H2S splitting technology was set as the baseline to compare with various other H2 production technologies. Scenario analysis was assessed by setting the solar-powered electricity as the baseline and was compared with electricity from different sources such as wind, nuclear and the United Arab Emirates (UAE) grid for the H2S splitting plant. Moreover, uncertainty analysis using Monte Carlo simulation suggests that the probability of gaining results of HTP is the highest between 3.62 × 10−4 to 1.34 × 10−3 kg 1,4-DCB. It can be concluded that electricity powered by renewable sources significantly reduces the environmental burden from the scenario analysis conducted.