Location: Sustainable Biofuels and Co-products Research
Title: Advances and challenges in hydrothermal processes for biomass conversion: feedstock flexibility, products, and modeling approachesAuthor
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ROJAS, MYRIAM - Karlsruhe Institute Of Technology |
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MANRIQUE, RAIZA - Oak Ridge Institute For Science And Education (ORISE) |
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HORNUNG, URSEL - Karlsruhe Institute Of Technology |
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Mullen, Charles |
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CHEJNE, FARID - Universidad De Colombia |
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MAYA, JUAN - University Of Colombia |
Submitted to: Biomass and Bioenergy
Publication Type: Review Article Publication Acceptance Date: 1/15/2025 Publication Date: 1/23/2025 Citation: Rojas, M., Manrique, R., Hornung, U., Mullen, C.A., Chejne, F., Maya, J.C. 2025. Advances and challenges in hydrothermal processes for biomass conversion: feedstock flexibility, products, and modeling approaches . Biomass and Bioenergy. 194 (March 2025): 107621. https://doi.org/10.1016/j.biombioe.2025.107621. DOI: https://doi.org/10.1016/j.biombioe.2025.107621 Interpretive Summary: Creating technology to convert biomass (like plants and organic waste) into energy carriers is crucial for moving to a low-carbon economy. New biorefineries—where these processes happen—rely on advanced techniques, like Hydrothermal Liquefaction (HTL), to convert wet, mixed materials such as municipal solid waste (MSW) and algae into bio-crude oil that can be upgraded into biofuels and other valuable products. For example, MSW offers a significant inexpensive feedstock, as there are about 1,300 million metric tons worldwide each year. This review discusses how HTL and similar processes are flexible enough to handle various types of waste—organic solids, food waste, and MSW. It also examines recent improvements in reactor design and how the process is modeled to optimize conditions. By identifying current challenges, research gaps, and potential improvements, this review suggests a clear path forward, combining theoretical and practical approaches to advance biorefinery technology and support a circular bioeconomy. This information will be useful to those considering the conversion of waste resources including those from agriculture to bio-crude oil via HTL. Technical Abstract: Developing technologies to harness biomass energy is essential for the transition to a low-carbon economy. Emerging biorefineries, where biomass energy is converted via thermochemical processes like Hydrothermal Liquefaction (HTL) can be at the core of this transition. This review offers a comprehensive analysis of biomass Hydrothermal Processes (HTP), emphasizing HTL as a sustainable approach to convert high-moisture, heterogeneous biomass—including municipal solid waste (MSW), lignocellulosic residues, and microalgae—into biofuels and valuable bioproducts. MSW, with an estimated global supply of 1,300 million metric tons annually, represents a significant potential for energy recovery. Optimized HTL processes have achieved up to 72% conversion rates for lignocellulosic biomass, while biocrude from algal biomass exhibits a heating value ranging from 36.6 to 39.3 MJ/kg, highlighting the efficiency and adaptability of HTL across diverse feedstocks. This review explores the flexibility of feedstocks suitable for HTP, including organic solid waste, food waste, and sludge, and critically assesses recent advances in reactor design, as well as kinetic and phenomenological modeling. The analysis identifies existing challenges in understanding the process, highlights research gaps, and proposes a roadmap for future studies. This roadmap integrates theoretical and experimental approaches aimed at accelerating the development of next-generation biorefineries and supporting the shift towards a circular bioeconomy. |