Producing green hydrogen from industrial waste gas
Hydrogen is considered as a future green energy, but 90% is currently generated from fossil fuel. It is estimated that 0.5 million tonnes of hydrogen are currently vented to the atmosphere in industrial waste gases. Dr He and her collaborator at Imperial College London, Dr Wu, are developing mixed-matrix membranes for hydrogen purification from these waste gap streams. Capturing and reusing this will contribute to reducing fossil fuel use, supporting the Academy’s strategic goal of creating a sustainable society.
Decarbonising hydrogen
Hydrogen is considered as a green energy source of the future, with over 30 countries releasing hydrogen roadmaps in 2021. It is expected that the total global investment in hydrogen will exceed $300 billion through 2030. However, 90% of the world’s hydrogen is generated from fossil fuel through well-established industrial methods including steam methane reforming, auto-thermal reforming, gasification of coal, and partial oxidation of hydrocarbons. Only 8% of hydrogen is made from electrolysis of water.
“This programme enables me to develop my leadership as a female researcher in engineering with training, support, mentoring, and funding from the UK Royal Academy of Engineering.”
Much of this hydrogen is used for large-scale industrial processes including petroleum refinery, ammonia production, coal refinement, organic and inorganic synthesis, and metallurgy. It is estimated that up to 0.5 million tonnes of hydrogen is currently vented to the atmosphere by these industries. These waste industrial gas streams can be an important source of hydrogen that has yet to be fully developed. Recovering and using this support’s the Academy’s strategic goal of using engineering to create a more sustainable society.
Dr He’s career has focused on better understanding air pollution and global warming problems and developing clean, renewable energy solutions to them. She has an expertise in using membrane technologies for gas separation and is applying this to this DIA-supported project. She is collaborating with Dr Wu at Imperial College London who, as well as creating a link with the UK, brings expertise in molecular dynamic simulation, used to model membrane technologies.
Recovering hydrogen from waste gases
The project team has identified two industrial hydrogen-rich waste gases: coke oven gas (COG) from steelmaking processes and ammonia purge gas (APG) from ammonia production. Both COG and APG consist of about 60% H2, which is mixed with other gases such CH4, CO, CO2, and N2. The hydrogen can be recovered through purification processes like pressure swing adsorption (PSA), fractional/cryogenic distillation, and membrane separation. The high cost of PSA and distillation make them unsuitable. The membrane technology has the advantages of high selectivity, low cost, low energy consumption, and a compact and modular design making it the best option for hydrogen recovery from industrial waste gas streams. However, using a membrane to recover hydrogen from waste gases is a recent innovation.
The project’s overarching goal is to develop new mixed-matrix membranes (MMMs) for hydrogen purification of COG and APG waste gases. The DIA-supported project will look at three research objectives. Firstly, molecular dynamics simulation will be used to understand the hydrogen purification mechanism. This helps identify the key parameters to improve membrane performance. Secondly, new membranes will be developed using one or two filler materials to create synergistic enhancements in the MMMs. Finally, through fine-tuning the porosity at a molecular-level of the filler materials, the molecular sieving capacity of the new membranes can be maximised.
This programme enables Dr He to develop her leadership as a female researcher in engineering with training, support, mentoring, and funding from the Academy. It will also strengthen the existing collaboration with her UK research partner, and in-person engagement with the UK engineering community, which has been extremely difficult in the past three years because of the pandemic. Finally, the programme enables her to build new links with UK researchers across the disciplines of hydrogen purification and membrane materials through the DIA programme’s peer-support network.