Prof. T. M. Indra Mahlia is a Distinguished Professor of Civil and Environmental Engineering at the University of Technology Sydney, in Australia. He is an internationally recognised authority in sustainable energy systems, techno-economic analysis, life cycle assessment (LCA), and energy–environment nexus research. He has secured more than $5 million in competitive research funding from government and industry and has authored several hundred peer-reviewed publications in leading Q1 journals. He has been consistently recognised as a Highly Cited Researcher in Engineering by Clarivate Analytics (2017–2022). His research directly informs energy policy, deployment of low-carbon technologies, and circular economy strategies, particularly in the Asia–Pacific region.Bidattul Syirat Zainal is a researcher and dedicated scholar in Environmental Engineering. Bidattul has successfully earned her PhD, specialising in pivotal areas such as Circular Economy, Biological Treatment, and Hydrogen Energy. Her research endeavours are driven by a passion to develop sustainable solutions that address the pressing environmental challenges of our time. After completing her doctoral studies in 2019, she furthered her research as a postdoctoral researcher at Universiti Kebangsaan Malaysia (UKM), Universiti Tenaga Nasional (UNITEN) and Sunway University, gaining valuable insights and experience in the field. Currently, she is continuing her role at the University of Malaya, Malaysia.