Bibliometric Analysis of Hydrothermal Co-Processing of Biomass for Energy Generation

Waste-to-energy technology plays a crucial role in advancing the circular economy framework, a strategy that contributes to achieving the United Nations Sustainable Development Goals on responsible consumption and production, as well as the provision of affordable and clean energy. Hydrothermal co-liquefaction has emerged as a promising technology for addressing waste material challenges by converting them into valuable biofuels. This review focuses on biomass feedstock classification and provides an overview of hydrothermal co-liquefaction for sustainable waste management and improved energy production. Moreover, the article provides details on integrating other waste treatment methods with hydrothermal liquefaction to promote the circular economy. Research publications from 2015 to 2025 were obtained from Web of Science and Scopus to identify research trends and output across countries and map out future research directions. The retrieved data from Web of Science was analysed for mapping research, keyword occurrence, and network analysis using VOSviewer software. The study highlighted that waste treatment techniques not only mitigate environmental pollution but also provide a sustainable pathway for energy production and contribute to global carbon neutrality. The review shows that biocrude yield varies with blending ratio because of differences in the biochemical composition of feedstocks, which affect reaction pathways and lead to synergistic or antagonistic interactions during co-processing. Therefore, careful selection of biomass feedstock is essential to achieve optimal results.