Agricultural biomass, including lignocellulosic residues and algal feedstocks, represents an abundant renewable resource with potential for sustainable energy production and environmental remediation. This review systematically explores the latest research on turning agricultural wastes into the agricultural circular economy via thermochemical conversion techniques. Biochar and hydrochar are two of the most frequently reported products, with applications that enhance crop yields by approximately 19. 9–36. 9% and contribute to soil improvement and pollutant remediation. Studies employing machine learning (ML), life cycle assessment (LCA), and techno-economic analysis (TEA) demonstrate the effectiveness of these approaches: ML-optimized biochar can reach specific surface areas up to 400. 0 m2/g, immobilize heavy metals in soil with efficiencies over 90. 0%, and remove contaminants from wastewater with efficiencies of 84. 0–90. 0% for heavy metals and 96. 5% for organic pollutants. LCA and TEA results confirm notable environmental and economic benefits, including greenhouse gas emission reductions of 1. 5 to 3. 5 tCO2-eq per ton and production costs as low as 116. 0/ton for biochar and 30. 0/ton for hydrochar. These findings provide a solid foundation for integrating thermochemical conversion into circular economy frameworks and advancing agricultural sustainability.
Fang et al. (Wed,) studied this question.