2024 pp. 1239-1259 Vol. 23 p-ISSN: 0972-6268 (Print copies up to 2016) No. 3 Nature Environment and Pollution Technology An International Quarterly Scientific Journal Original Review Paper e-ISSN: 2395-3454 Open Access Journal Original Research Paper https://doi.org/10.46488/NEPT.2024.v23i03.002 Advanced Waste-to-Energy Technologies: A Review on Pathway to Sustainable Energy Recovery in a Circular Economy C. G. Achi† , J. Snyman, J. M. Ndambuki and W. K. Kupolati Department of Civil Engineering, Faculty of the Built Environment, Tshwane University of Technology, Pretoria West, South Africa †Corresponding author: C. G. Achi; achicg@tut.ac.za; achicgjr@gmail.com ABSTRACT In the face of the rapid rise in global waste production and the pressing need to shift towards sustainable energy options, advanced Waste-to-Energy (WtE) technologies have emerged as a highly promising solution. These innovative technologies effectively utilize waste as a valuable resource, presenting a viable pathway for sustainable energy recovery and making a substantial contribution to the principles of the circular economy paradigm. This review provides a comprehensive overview of advanced WtE technologies, including thermal, biological, and chemical methods, such as gasification, pyrolysis, plasma arc gasification, anaerobic digestion, fermentation, transesterification, and hydrothermal carbonization. The efficiency of these technologies is evaluated based on their energy recovery potential, environmental impact, and economic feasibility. Case studies on successful implementations of advanced WtE technologies are analyzed to highlight their practicality and effectiveness. Finally, the paper addresses technical, regulatory, and policy challenges in this field and provides future perspectives. The objective is to underscore the role of advanced WtE technologies in achieving a sustainable and resource-efficient circular economy. INTRODUCTION The consistent and rapid increase in global waste generation and the pressing need to shift towards sustainable energy sources present significant challenges for society. According to the World Bank, global waste generation could increase by 70% from 2016 levels to 3.40 billion tonnes per year by 2050, driven by rapid urbanization and growing populations (Kaza et al. 2018). Simultaneously, the growing impacts of climate change and the depletion of finite fossil fuel reserves demand a transition towards renewable and sustainable energy sources. In this context, waste-to-energy (WtE) technologies, particularly advanced systems, have emerged as a promising solution based on the need to adopt policies that will enhance the affordability, reliability, and sustainability of energy (IEA 2022). These WtE technologies have the potential to transform vast amounts of waste into valuable energy resources, such as heat and electricity, thereby providing a pathway toward sustainable energy recovery. By converting waste into energy, these technologies not only help manage waste but also contribute to the diversification of energy sources and the reduction of greenhouse gas emissions. Additionally, WtE technologies align with the principles of a circular economy, an economic system aimed at eliminating waste through the continual use of resources (Boloy et al. 2021). In a circular economy, waste is viewed not as a problem but as a resource that can be harnessed for value creation (Hari Bhakta et al. 2021). Advanced WtE technologies exemplify this strategy by converting waste into energy, thereby contributing to a more sustainable and resource-efficient economy. This convergence of waste management, energy recovery, and circular economy principles presents a compelling rationale for a deeper examination of advanced WtE technologies. Understanding their potential, efficiency, and the challenges they face is crucial for their successful implementation and for realizing a sustainable circular economy. Research Questions, Objectives, and Scope of the Review These research questions guided this study (a) How does the principle of circular economy intersect with waste management and energy recovery? (b) What criteria should be adopted in evaluating advanced waste-to-energy technologies in conformity with the principles of sustainability within the circular economy model? Nat. Env. & Poll. Tech. Website: www.neptjournal.com Received: 18-10-2023 Revised: 08-12-2023 Accepted: 17-12-2023 Key Words: Environmental sustainability Advanced thermal technology Biochemical conversion Energy efficiency