Promising products based on hydrothermal liquefaction of agricultural biomass: an overview

The increasing global energy demand has driven the exploration of renewable alternatives to address the environmental challenges associated with conventional energy sources. In this context, agricultural, algae, and waste biomasses have emerged as highly promising and widely available renewable resources for the production of bioproducts through hydrothermal processes. Among these, hydrothermal liquefaction (HTL) is notable for its ability to convert wet lignocellulosic biomass in an aqueous medium, operating at lower temperatures and shorter retention times compared to pyrolysis. The primary product of HTL is biocrude. However, the process also generates high-value by-products with diverse applications. Therefore, this work provides a comprehensive literature review of the recent key aspects of HTL for biomass conversion. To achieve this, a systematic search was conducted, resulting in the selection of relevant articles published between 2015 and 2025. Recent studies report biocrude yields exceeding 50% for agricultural residues, with reaction times as short as 15 min. Furthermore, HTL facilitates the production of nitrogen and phosphate-based biofertilizers, supporting the recovery and reuse of these essential nutrients. It contributes to the synthesis of several valuable biochemical compounds, used in plastics, pesticides, and pharmaceutical industries. Consequently, biomass conversion via HTL represents a promising alternative to reduce environmental impacts while generating high-added-value products.