A study on comparative environmental impact assessment of thermochemical cycles and steam methane reforming processes for hydrogen production processes

Abstract

Alternative energy sources are extensively studied to meet the increasing energy demand. To address rising energy demand, hydrogen generation through environmentally friendly sources are explored, and new technologies are now needed badly. Hydrogen can be generated using fossil fuels, nuclear energy and renewable energy. Most of the hydrogen is still produced using fossil-based fuels, which increases the amount of greenhouse gases. This study examines the life-cycle impact of three alternative hydrogen-generating processes. The solar-based hybrid sulfur (HyS) thermochemical cycle, the nuclear-based HyS thermochemical cycle, and steam methane reforming (SMR) are all considered, and the environmental consequences of the SMR and thermochemical facilities are evaluated. The CML-IA impact categories are used to analyze environmental impacts. The SimaPro 9.2, a modeling software package developed for the detailed descriptions and simulations of complex products, services and processes, is used to perform the life cycle impact assessment (LCIA). This study aims to determine the best environmentally friendly option for hydrogen production by analyzing and comparing its environmental implications. Different impact categories namely global warming potential (GWP), human toxicity potential (HTP), ozone layer depletion (ODP), abiotic depletion factor (ADF), and acidification potential (AP), are examined based on the CML-IA impact classifications. The results show that the solar-based HyS cycle options yield the lowest global warming potential, abiotic depletion, acidification potential, ozone layer depletion, and human toxicity potential values were 1.04 kg CO2 eq/kg H2, 0.013 kg Sb eq/kg H2, 0.0027 kg SO2 eq/kg H2, 0.0007 kg CFC-11 eq/kg H2, and 0.27 kg 1,4-DB-eq/kg H2, respectively. The environmental impact results further show that the solar-powered hydrogen generation is a promising approach for cleaner hydrogen generation.