Biochar in the circular bioeconomy: a bibliometric analysis of technologies, applications, and trends

Biochar has attracted considerable attention in recent years for its wide-ranging applications, particularly its role in carbon sequestration as a strategy to mitigate greenhouse gas emissions. Its emerging uses within the circular bioeconomy also position it as a valuable tool for environmental management, and ongoing research continues to advance understanding of its mitigation potential. This article provides a comprehensive overview of biochar research development and applications. It includes a bibliometric analysis for the 2019–2023 period, complemented by a critical review of key technologies, characterization methods, and applications. This integrated approach clarifies the current state of biochar research and highlights emerging trends in its applications. The study reveals that 20 041 articles and reviews were published over the period from 2019 to 2023, highlighting China as the leading country in biochar research and development. Residual biomass is considered the feedstock of choice for biochar production, with pyrolysis emerging as the dominant technology, surpassing gasification and torrefaction. Adsorption has gained prominence for its potential in remediating contaminated soils. Emerging applications of biochar include its use in anaerobic digestion within the circular economy, warranting further investigation for full integration. Biochar is also increasingly recognized as a viable option for greenhouse gas (GHG) mitigation, with growing interest in its diverse applications. This article provides a comprehensive review of recent advancements in biochar research, emphasizing key trends and prospective applications across various sectors.