Solar integrated hydrothermal processes: A review

Hydrothermal Treatment of Biomass Feedstocks for Sustainable Production of Chemicals, Fuels, and Materials: Progress and Perspectives

“…In recent years, the development of renewable energy-based hydrothermal technologies has received considerable attention for biomass valorization in the context of mitigating climate change, depletion of fossil fuels, and environmental pollution . To make the hydrothermal process more economically environmentally appealing, concentrating solar technology (CST) (e.g., parabolic trough concentrator) is integrated with hydrothermal systems, which provides high temperature (200–3000 °C) and high heating rate (5–450 °C/s) depending on the type of solar concentrator. , Solar-based hydrothermal biomass valorization could be an attractive option for tropical countries which receive optimum direct solar irradiation for longer time.…”

“…The integration of solar energy with hydrothermal process was usually conducted in direct and indirect systems (Figure ). , In the direct route, solar reactors are usually designed to adsorb solar radiation and provide hydrothermal conditions for transformation of biomass feedstocks. , In contrast, an indirect system is usually performed in a separated loop by coupling heat transfer system and conventional hydrothermal reactors. , The operation routes and heat flow of direct and indirect systems are explained by the developed systems as shown in Figure . In the solar HTC system (Figure a), conventional HTC reactor was coated with copper oxide to maximize the radiation adsorption as a solar reactor .…”

“…In the indirect route, heat from solar energy was first adsorbed and collected by a solar receiver (e.g., solar concentrator-based system). , The heat was supplied into conventional hydrothermal reactors. , In the proposed solar energy-based plant (Figure b), heat from the solar field (assembled by solar concentrator) was transferred into hydrothermal reactors for the gasification of algae. , The produced syngas produced from HTG was used to prepare gasoline and diesel with addition of hydrogen integrated with photovoltaic (PV) electrolysis system. , Solar energy-based system has been also developed for syngas production in a pilot plant (Figure c). , Specifically, heat from solar concentrator was collected to supply hydrothermal reactor under HTG conditions (700–800 °C, 250–350 bar) by heat exchanger system. , Additionally, a techno-economic analysis has confirmed the sustainability of solar energy-based hydrothermal system, which is discussed in section . , …”

“…The integration of solar energy with hydrothermal process was usually conducted in direct and indirect systems (Figure 45). 28,29 In the direct route, solar reactors are usually designed to adsorb solar radiation and provide hydrothermal conditions for transformation of biomass feedstocks. 28,29 In contrast, an indirect system is usually performed in a separated loop by coupling heat transfer system and conventional hydrothermal reactors.…”

“…28,29 In the direct route, solar reactors are usually designed to adsorb solar radiation and provide hydrothermal conditions for transformation of biomass feedstocks. 28,29 In contrast, an indirect system is usually performed in a separated loop by coupling heat transfer system and conventional hydrothermal reactors. 28,29 The operation routes and heat flow of direct and indirect systems are explained by the developed systems as shown in Figure 45.…”