Environmental performance of the HAS-Clay, Kanuma-Clay, and coffee residue adsorbents for bio-H₂purification

Recently, a fuel cell (FC) system operated by hydrogen from a renewable source (e.g., biomass feedstock) has been developed to contribute to the abatement of environmental impact and create an environmental business model. In this study, bio-hydrogen produced through a biomass gasification process was investigated. Considering the use of bio-hydrogen, production efficiency and fuel cost are issues of concern. In terms of the technological barriers, the removal of impurities and performance related to the plant cost are considerably influenced by the operating cost and eco-burden. In this study, we focus on a removal system that uses an eco-friendly adsorbent. These impurities should be eliminated to prevent the voltage drop of FC stack. Additionally, in terms of a life cycle analysis (LCA), the performance and the content of the adsorbent would be considerably affected. In our first study, hydroxyl aluminum silicate clay (HAS-Clay) or a natural soil of Kanuma-Clay was a potential candidate. Evidently, HAS-Clay and Kanuma-Clay had a good potential to simultaneously remove H2S, HCl, and NH3. However, the eco-burden of HAS-Clay cannot be mitigated in comparison to that of conventional adsorbents. Therefore, as alternative adsorbents, we selected coffee residue, and the adsorption performance was tested. Using these performances data, the life cycle impact analysis (LCIA) was evaluated in comparison to the eco-burdens of HAS-Clay and Kanuma-Clay. Especially, it is extremely significant to find out the adsorption possibility of coffee residue from a recycling viewpoint. Here, global warming potential and abiotic depletion potential were the indices used for the LCIA. Consequently, coffee residue has a sufficient benefit from the environmental aspect.