• Energy Research

Waste management is one of the biggest environmental challenges worldwide. Biomass-derived hard carbons, which can be applied to rechargeable batteries, can contribute to mitigating environmental changes by enabling the use of renewable energy. This study has carried out a comparative environmental assessment of sustainable hard carbons, produced from System A (hydrothermal carbonization (HTC) followed by pyrolysis) and System B (direct pyrolysis) with different carbon yields, as anodes in sodium-ion batteries (SIBs). We have also analysed different scenarios to save energy in our processes and compared the biomass-derived hard carbons with commercial graphite used in lithium-ion batteries. The life cycle assessment results show that the two systems display significant savings in terms of their global warming potential impact (A1: −30%; B1: −21%), followed by human toxicity potential, photochemical oxidants creation potential, acidification potential and eutrophication potential (both over −90%). Possessing the best electrochemical performance for SIBs among our prepared hard carbons, the HTC-based method is more stable in both environmental and electrochemical aspects than the direct pyrolysis method. Such results help a comprehensive understanding of sustainable hard carbons used in SIBs and show an environmental potential to the practical technologies. This article is part of the theme issue ‘Bio-derived and bioinspired sustainable advanced materials for emerging technologies (part 2)’.

AbstractThe production of bio‐ethylene is a promising way to replace fossil‐based ethylene production, reducing greenhouse gas emissions and working towards China's carbon neutrality goals. This study elaborates on five bio‐ethylene technological pathways: first‐ and second‐generation bioethanol dehydration, direct and indirect thermochemical synthesis, and methanol‐to‐olefins (MTO). It retrieves information about them from commercial patents and the scientific literature, and comprehensively assesses their potential for application in large‐scale ethylene production in China. The techno‐economic feasibility of these five technological pathways is discussed in terms of feedstock availability, investment level, technological development level, and political issues such as the carbon neutrality goal to which China's government is committed. Overall, two pathways (indirect thermochemical synthesis and MTO) exhibited competitive minimum ethylene selling prices at 5243 yuan/t (822 USD t–1) and 6767 yuan/t (1061 USD t–1), respectively, of which both are lower than the average ethylene market price of 7000 yuan/t (1098 USD t–1). In comparison with the conventional fossil‐derived ethylene, bio‐ethylene could decrease carbon emission by 3.2%–15.1% under a scenario of 20% bio‐ethylene substitution in 2019, showing promising potential for decarbonizing the ethylene industry and contributing to the achievement of China's carbon neutrality goals. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.