Abstract:
Biomass plays a key role in capturing and storing solar energy on Earth. It is estimated that up to 8,500 exjoules (×10¹⁸ joules) of solar energy are captured and stored globally each year through biomass, which is about 10-15 times the current global energy consumption (580 exajoules). This presentation provides an overview of the availability of biomass and organic solid waste resources globally, as well as in Chinese mainland and Hong Kong, and introduces hydrothermal technologies and their applications in the transformation of biomass and organic solid waste. During these transformations, water is used as a reaction medium, solvent, reactant, or catalyst. Hydrothermal technology is especially suitable for the resource utilization of high-moisture biomass and biowaste (such as food waste, sewage sludge, manure slurry, microalgae, etc.), as it eliminates the costly dehydration/drying process (which is essential for other thermochemical processes like combustion, pyrolysis, and gasification). This presentation summarizes Professor Xu's team's past research achievements in various hydrothermal technology development, including methanol aqueous phase reforming (APR) for hydrogen production, biomass hydrothermal carbonization (HTC) to produce water-charcoal, hydrothermal liquefaction of biomass waste (HTL) to produce biocrude oil, and supercritical water gasification (SCWG) of aqueous biomass (sugars) to produce green hydrogen. Professor Xu will also share his experience in scaling HTL technology to 6 kg/h and 100 kg/h, as well as ongoing commercialization efforts, including building pilot units with a daily throughput of 10 tons and demonstration units with a daily throughput of 100 tons.
Biography
Professor Charles XU is a Fellow of Canadian Academy of Engineering and was newly elected as a Fellow of Royal Society of Canada in 2026. As of July 2026, he serves as Director of the Research Centre for Resources Engineering towards Carbon Neutrality (https://www.polyu.edu.hk/rcre/) at The Hong Kong Polytechnic University and Chair Professor of Advanced Biorefining in the Department of Civil and Environmental Engineering. He has served as Chair Professor of Advanced Biorefinery at the School of Energy and Environment, City University of Hong Kong, tenured full professor at Western University in Canada, and the NSERC/FPInnovations Industrial Research Chair in Forest Biorefinery. With over 20 years of research experience in advanced biorefining, his research areas include the conversion of biomass and biological resources into bio-based chemicals/materials, efficient use of hydrothermal liquefaction/carbonization methods to produce low-carbon fuels or biofuels and biocarbon materials, green hydrogen production/storage and biomass metallurgy. He has published over 400 peer-reviewed journal papers, with more than 30,000 citations and an H-index of 90. He has received the Research Excellence Award from the Japan Energy Society (1999), the Syncrude Canada Innovation Award (2011) and the Industrial Design and Practice Award (2019) from the Canadian Society of Chemical Engineers, the Changjiang Scholars Chair Professor Award from China's Ministry of Education (2020), and the Humboldt Research Award from Germany's Humboldt Foundation in 2023.He is serving as an editor or associate editor for many journals such as Bioresource Technology, Biomass and Bioenergy, etc.