Sign in to use this feature.

Years

Between: -

Subjects

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Journals

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Article Types

Countries / Regions

remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline
remove_circle_outline

Search Results (873)

Search Parameters:
Keywords = thermochemical process

Order results
Result details
Results per page
Select all
Export citation of selected articles as:
45 pages, 1629 KiB  
Review
Direct Air Capture Using Pyrolysis and Gasification Chars: Key Findings and Future Research Needs
by Wojciech Jerzak, Bin Li, Dennys Correia da Silva and Glauber Cruz
Energies 2025, 18(15), 4120; https://doi.org/10.3390/en18154120 (registering DOI) - 3 Aug 2025
Abstract
Direct Air Capture (DAC) is gaining worldwide attention as a negative emissions strategy critical to meeting climate targets. Among emerging DAC materials, pyrolysis chars (PCs) and gasification chars (GCs) derived from biomass present a promising pathway due to their tunable porosity, surface [...] Read more.
Direct Air Capture (DAC) is gaining worldwide attention as a negative emissions strategy critical to meeting climate targets. Among emerging DAC materials, pyrolysis chars (PCs) and gasification chars (GCs) derived from biomass present a promising pathway due to their tunable porosity, surface chemistry, and low-cost feedstocks. This review critically examines the current state of research on the physicochemical properties of PCs and GCs relevant to CO2 adsorption, including surface area, pore structure, surface functionality and aromaticity. Comparative analyses show that chemical activation, especially with KOH, can significantly improve CO2 adsorption capacity, with some PCs achieving more than 308 mg/g (100 kPa CO2, 25 °C). Additionally, nitrogen and sulfur doping further improves the affinity for CO2 through increased surface basicity. GCs, although inherently more porous, often require additional modification to achieve a similar adsorption capacity. Importantly, the long-term stability and regeneration potential of these chars remain underexplored, but are essential for practical DAC applications and economic viability. The paper identifies critical research gaps related to material design and techno-economic feasibility. Future directions emphasize the need for integrated multiscale research that bridges material science, process optimization, and real-world DAC deployment. A synthesis of findings and a research outlook are provided to support the advancement of carbon-negative technologies using thermochemically derived biomass chars. Full article
(This article belongs to the Section B3: Carbon Emission and Utilization)
30 pages, 2603 KiB  
Review
Sugarcane Industry By-Products: A Decade of Research Using Biotechnological Approaches
by Serafín Pérez-Contreras, Francisco Hernández-Rosas, Manuel A. Lizardi-Jiménez, José A. Herrera-Corredor, Obdulia Baltazar-Bernal, Dora A. Avalos-de la Cruz and Ricardo Hernández-Martínez
Recycling 2025, 10(4), 154; https://doi.org/10.3390/recycling10040154 (registering DOI) - 2 Aug 2025
Abstract
The sugarcane industry plays a crucial economic role worldwide, with sucrose and ethanol as its main products. However, its processing generates large volumes of by-products—such as bagasse, molasses, vinasse, and straw—that contain valuable components for biotechnological valorization. This review integrates approximately 100 original [...] Read more.
The sugarcane industry plays a crucial economic role worldwide, with sucrose and ethanol as its main products. However, its processing generates large volumes of by-products—such as bagasse, molasses, vinasse, and straw—that contain valuable components for biotechnological valorization. This review integrates approximately 100 original research articles published in JCR-indexed journals between 2015 and 2025, of which over 50% focus specifically on sugarcane-derived agroindustrial residues. The biotechnological approaches discussed include submerged fermentation, solid-state fermentation, enzymatic biocatalysis, and anaerobic digestion, highlighting their potential for the production of biofuels, enzymes, and high-value bioproducts. In addition to identifying current advances, this review addresses key technical challenges such as (i) the need for efficient pretreatment to release fermentable sugars from lignocellulosic biomass; (ii) the compositional variability of by-products like vinasse and molasses; (iii) the generation of metabolic inhibitors—such as furfural and hydroxymethylfurfural—during thermochemical processes; and (iv) the high costs related to inputs like hydrolytic enzymes. Special attention is given to detoxification strategies for inhibitory compounds and to the integration of multifunctional processes to improve overall system efficiency. The final section outlines emerging trends (2024–2025) such as the use of CRISPR-engineered microbial consortia, advanced pretreatments, and immobilization systems to enhance the productivity and sustainability of bioprocesses. In conclusion, the valorization of sugarcane by-products through biotechnology not only contributes to waste reduction but also supports circular economy principles and the development of sustainable production models. Full article
Show Figures

Graphical abstract

19 pages, 2806 KiB  
Article
Operating Solutions to Improve the Direct Reduction of Iron Ore by Hydrogen in a Shaft Furnace
by Antoine Marsigny, Olivier Mirgaux and Fabrice Patisson
Metals 2025, 15(8), 862; https://doi.org/10.3390/met15080862 (registering DOI) - 1 Aug 2025
Viewed by 134
Abstract
The production of iron and steel plays a significant role in the anthropogenic carbon footprint, accounting for 7% of global GHG emissions. In the context of CO2 mitigation, the steelmaking industry is looking to potentially replace traditional carbon-based ironmaking processes with hydrogen-based [...] Read more.
The production of iron and steel plays a significant role in the anthropogenic carbon footprint, accounting for 7% of global GHG emissions. In the context of CO2 mitigation, the steelmaking industry is looking to potentially replace traditional carbon-based ironmaking processes with hydrogen-based direct reduction of iron ore in shaft furnaces. Before industrialization, detailed modeling and parametric studies were needed to determine the proper operating parameters of this promising technology. The modeling approach selected here was to complement REDUCTOR, a detailed finite-volume model of the shaft furnace, which can simulate the gas and solid flows, heat transfers and reaction kinetics throughout the reactor, with an extension that describes the whole gas circuit of the direct reduction plant, including the top gas recycling set up and the fresh hydrogen production. Innovative strategies (such as the redirection of part of the bustle gas to a cooling inlet, the use of high nitrogen content in the gas, and the introduction of a hot solid burden) were investigated, and their effects on furnace operation (gas utilization degree and total energy consumption) were studied with a constant metallization target of 94%. It has also been demonstrated that complete metallization can be achieved at little expense. These strategies can improve the thermochemical state of the furnace and lead to different energy requirements. Full article
(This article belongs to the Special Issue Recent Developments and Research on Ironmaking and Steelmaking)
Show Figures

Graphical abstract

24 pages, 3016 KiB  
Article
Industrial Off-Gas Fermentation for Acetic Acid Production: A Carbon Footprint Assessment in the Context of Energy Transition
by Marta Pacheco, Adrien Brac de la Perrière, Patrícia Moura and Carla Silva
C 2025, 11(3), 54; https://doi.org/10.3390/c11030054 - 23 Jul 2025
Viewed by 429
Abstract
Most industrial processes depend on heat, electricity, demineralized water, and chemical inputs, which themselves are produced through energy- and resource-intensive industrial activities. In this work, acetic acid (AA) production from syngas (CO, CO2, and H2) fermentation is explored and [...] Read more.
Most industrial processes depend on heat, electricity, demineralized water, and chemical inputs, which themselves are produced through energy- and resource-intensive industrial activities. In this work, acetic acid (AA) production from syngas (CO, CO2, and H2) fermentation is explored and compared against a thermochemical fossil benchmark and other thermochemical/biological processes across four main Key Performance Indicators (KPI)—electricity use, heat use, water consumption, and carbon footprint (CF)—for the years 2023 and 2050 in Portugal and France. CF was evaluated through transparent and public inventories for all the processes involved in chemical production and utilities. Spreadsheet-traceable matrices for hotspot identification were also developed. The fossil benchmark, with all the necessary cascade processes, was 0.64 kg CO2-eq/kg AA, 1.53 kWh/kg AA, 22.02 MJ/kg AA, and 1.62 L water/kg AA for the Portuguese 2023 energy mix, with a reduction of 162% of the CO2-eq in the 2050 energy transition context. The results demonstrated that industrial practices would benefit greatly from the transition from fossil to renewable energy and from more sustainable chemical sources. For carbon-intensive sectors like steel or cement, the acetogenic syngas fermentation appears as a scalable bridge technology, converting the flue gas waste stream into marketable products and accelerating the transition towards a circular economy. Full article
(This article belongs to the Section Carbon Cycle, Capture and Storage)
Show Figures

Graphical abstract

35 pages, 1196 KiB  
Review
Reversible Thermochemical Routes for Carbon Neutrality: A Review of CO2 Methanation and Steam Methane Reforming
by Marisa Martins, Carlos Andrade and Amadeu D. S. Borges
Physchem 2025, 5(3), 29; https://doi.org/10.3390/physchem5030029 - 23 Jul 2025
Viewed by 333
Abstract
This review explores CO2 methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility [...] Read more.
This review explores CO2 methanation and steam methane reforming (SMR) as two key thermochemical processes governed by reversible reactions, each offering distinct contributions to carbon-neutral energy systems. The objective is to provide a comparative assessment of both processes, highlighting how reaction reversibility can be strategically leveraged for decarbonization. The study addresses methane production via CO2 methanation and hydrogen production via SMR, focusing on their thermodynamic behaviors, catalytic systems, environmental impacts, and economic viability. CO2 methanation, when powered by renewable hydrogen, can result in emissions ranging from −471 to 1076 kg CO2-equivalent per MWh of methane produced, while hydrogen produced from SMR ranges from 90.9 to 750.75 kg CO2-equivalent per MWh. Despite SMR’s lower production costs (USD 21–69/MWh), its environmental footprint is considerably higher. In contrast, methanation offers environmental benefits but remains economically uncompetitive (EUR 93.53–204.62/MWh). Both processes rely primarily on Ni-based catalysts, though recent developments in Ru-based and bimetallic systems have demonstrated improved performance. The review also examines operational challenges such as carbon deposition and catalyst deactivation. By framing these technologies through the shared lens of reversibility, this work outlines pathways toward integrated, efficient, and circular energy systems aligned with long-term sustainability and climate neutrality goals. Full article
(This article belongs to the Section Kinetics and Thermodynamics)
Show Figures

Figure 1

31 pages, 2773 KiB  
Review
Actualized Scope of Forestry Biomass Valorization in Chile: Fostering the Bioeconomy
by Cecilia Fuentalba, Victor Ferrer, Luis E. Arteaga-Perez, Jorge Santos, Nacarid Delgado, Yannay Casas-Ledón, Gastón Bravo-Arrepol, Miguel Pereira, Andrea Andrade, Danilo Escobar-Avello and Gustavo Cabrera-Barjas
Forests 2025, 16(8), 1208; https://doi.org/10.3390/f16081208 - 23 Jul 2025
Viewed by 510
Abstract
Chile is among the leading global exporters of pulp and paper, supported by extensive plantations of Pinus radiata and Eucalyptus spp. This review synthesizes recent progress in the valorization of forestry biomass in Chile, including both established practices and emerging bio-based applications. It [...] Read more.
Chile is among the leading global exporters of pulp and paper, supported by extensive plantations of Pinus radiata and Eucalyptus spp. This review synthesizes recent progress in the valorization of forestry biomass in Chile, including both established practices and emerging bio-based applications. It highlights advances in lignin utilization, nanocellulose production, hemicellulose processing, and tannin extraction, as well as developments in thermochemical conversion technologies, including torrefaction, pyrolysis, and gasification. Special attention is given to non-timber forest products and essential oils due to their potential bioactivity. Sustainability perspectives, including Life Cycle Assessments, national policy instruments such as the Circular Economy Roadmap and Extended Producer Responsibility (REP) Law, are integrated to provide context. Barriers to technology transfer and industrial implementation are also discussed. This work contributes to understanding how forestry biomass can support Chile’s transition toward a circular bioeconomy. Full article
Show Figures

Figure 1

22 pages, 4775 KiB  
Article
Numerical Simulation of Paraffin Energetic Performance Enhanced by KNO3, NH4NO3, Al, Ti, and Stearic Acid for Hybrid Rocket Applications
by Grigore Cican and Alexandru Mitrache
Fuels 2025, 6(3), 54; https://doi.org/10.3390/fuels6030054 - 19 Jul 2025
Viewed by 327
Abstract
This study investigates the energy performance of paraffin-based hybrid fuels enhanced with potassium nitrate (KNO3), ammonium nitrate (NH4NO3), aluminum (Al), titanium (Ti), and stearic acid additives. The fuels were evaluated using thermochemical calculations via ProPEP3 Version 1.0.3.0 [...] Read more.
This study investigates the energy performance of paraffin-based hybrid fuels enhanced with potassium nitrate (KNO3), ammonium nitrate (NH4NO3), aluminum (Al), titanium (Ti), and stearic acid additives. The fuels were evaluated using thermochemical calculations via ProPEP3 Version 1.0.3.0 software, revealing significant improvements in specific impulse (Isp) and combustion temperature. While formulations with nitrates and aluminum exhibited noticeable increases in combustion efficiency and thermal output, titanium-containing mixtures provided moderate improvements. Stearic acid improved fuel processability and provided a stable burning profile without significant energy penalties. These findings demonstrate that suitable combinations of additives can substantially improve the energy output of paraffin-based hybrid fuels, making them more viable for aerospace propulsion applications. Full article
(This article belongs to the Special Issue Sustainable Jet Fuels from Bio-Based Resources)
Show Figures

Figure 1

19 pages, 1065 KiB  
Review
Recovery of Nutrients from the Aqueous Phase of Hydrothermal Liquefaction—A Review
by Barbara Camila Bogarin Cantero, Yalin Li, Prasanta Kalita, Yuanhui Zhang and Paul Davidson
Water 2025, 17(14), 2099; https://doi.org/10.3390/w17142099 - 14 Jul 2025
Viewed by 558
Abstract
Hydrothermal liquefaction (HTL) is a thermochemical conversion process that converts wet biomass into biocrude oil, a gas phase, a solid phase, and an aqueous phase (HTL-AP). An obstacle to the development and scaling of HTL is the volume of HTL-AP produced during the [...] Read more.
Hydrothermal liquefaction (HTL) is a thermochemical conversion process that converts wet biomass into biocrude oil, a gas phase, a solid phase, and an aqueous phase (HTL-AP). An obstacle to the development and scaling of HTL is the volume of HTL-AP produced during the process, which has high concentrations of nitrogen and carbon and cannot be disposed of in the environment without treatment. The HTL-AP is enriched with organic compounds, particularly light polar organics and nitrogenous compounds, which are inhibitory to microbial treatment in wastewater treatment plants. For this reason, the valorization of the HTL-AP is significant for the circular economy of HTL. This review synthesizes published findings on different types of treatment of the HTL-AP for the recovery of valuable nutrients and the removal of toxic compounds. This work outlines the trade-offs of the treatments to serve as a guide for future research to address these weaknesses and improve the valorization of the HTL-AP. Furthermore, this work uniquely focuses on HTL-AP treatment for recovering plant-available nitrogen, targeting its potential use as a fertilizer. The literature highlights the importance of increasing nitrogen bioavailability in HTL-AP through two-step treatments and by selecting HTL-AP derived from protein-rich feedstocks, which offer higher initial nitrogen content. According to the current state of research, further work is needed to optimize chemical and biological treatments for nutrient recovery from HTL-AP, particularly regarding treatment scale and duration. Additionally, economic analyses across different treatment types are currently lacking, but are essential to evaluate their feasibility and practicality. Full article
(This article belongs to the Special Issue Emerging Technologies for Nutrient Recovery and Wastewater Treatment)
Show Figures

Figure 1

31 pages, 5892 KiB  
Article
RANS Simulation of Turbulent Flames Under Different Operating Conditions Using Artificial Neural Networks for Accelerating Chemistry Modeling
by Tobias Reiter, Jonas Volgger, Manuel Früh, Christoph Hochenauer and Rene Prieler
Processes 2025, 13(7), 2220; https://doi.org/10.3390/pr13072220 - 11 Jul 2025
Viewed by 508
Abstract
Combustion modeling using computational fluid dynamics (CFD) offers detailed insights into the flame structure and thermo-chemical processes. Furthermore, it has been extensively used in the past to optimize industrial furnaces. Despite the increasing computational power, the prediction of the reaction kinetics in flames [...] Read more.
Combustion modeling using computational fluid dynamics (CFD) offers detailed insights into the flame structure and thermo-chemical processes. Furthermore, it has been extensively used in the past to optimize industrial furnaces. Despite the increasing computational power, the prediction of the reaction kinetics in flames is still related to high calculation times, which is a major drawback for large-scale combustion systems. To speed-up the simulation, artificial neural networks (ANNs) were applied in this study to calculate the chemical source terms in the flame instead of using a chemistry solver. Since one ANN may lack accuracy for the entire input feature space (temperature, species concentrations), the space is sub-divided into four regions/ANNs. The ANNs were tested for different fuel mixtures, degrees of turbulence, and air-fuel/oxy-fuel combustion. It was found that the shape of the flame and its position were well predicted in all cases with regard to the temperature and CO. However, at low temperature levels (<800 K), in some cases, the ANNs under-predicted the source terms. Additionally, in oxy-fuel combustion, the temperature was too high. Nevertheless, an overall high accuracy and a speed-up factor for all simulations of 12 was observed, which makes the approach suitable for large-scale furnaces. Full article
Show Figures

Figure 1

36 pages, 23568 KiB  
Article
Evaluation of the Reliability of Thermogravimetric Indices for Predicting Coal Performance in Utility Systems
by Krzysztof M. Czajka
Energies 2025, 18(13), 3473; https://doi.org/10.3390/en18133473 - 1 Jul 2025
Viewed by 231
Abstract
A thorough understanding of fuel behaviour is essential for designing and operating thermochemical systems. Thermogravimetric analysis (TGA) is among the most widely used fuel characterization methods, offering parameters like reactivity and ignition temperature, and enabling comprehensive fuel behaviour assessment through combined indices. This [...] Read more.
A thorough understanding of fuel behaviour is essential for designing and operating thermochemical systems. Thermogravimetric analysis (TGA) is among the most widely used fuel characterization methods, offering parameters like reactivity and ignition temperature, and enabling comprehensive fuel behaviour assessment through combined indices. This study critically examines the applicability of TGA-based indices for predicting coal performance in industrial processes such as gasification and combustion, where devolatilization, ignition, and burnout stages are key. TGA-derived data are compared with results from established methods, including drop tube furnace (DTF), pulse ignition (PI), and entrained flow reactor (EFR) tests. Findings indicate that the Volatile Matter Release Index (D2) effectively predicts DTF behaviour (R2 = 0.938, max residuals: 4.1 pp), proving useful for fast devolatilization analysis. The Flammability Index (C1) and Ignition Index (C3) correlate well with PI results (R2 = 0.927 and 0.931, max residuals: 53.3a °C), making them reliable ignition indicators. While TGA tools showed limited accuracy in burnout prediction, the proposed Modified Burnout Characteristic Index (B1′) achieved reasonable performance (R2 = 0.734, max residuals: 0.062%∙°C−1). Overall, selected TGA-based indices offer strong predictive potential for key thermochemical conversion stages. Full article
(This article belongs to the Special Issue Towards Cleaner and More Efficient Combustion)
Show Figures

Figure 1

16 pages, 3504 KiB  
Article
Production of Biochar from Plantain Rachis and Cassava Peel Towards Sustainable Management of Caribbean Agricultural Waste
by Adriana Patricia Herazo, Alejandra Zambrano, Lorena Marín, Julio Mass and Diana Nathalie Montenegro
Processes 2025, 13(7), 2059; https://doi.org/10.3390/pr13072059 - 29 Jun 2025
Viewed by 388
Abstract
The Caribbean faces many environmental issues, and the mitigation and adaptation strategies to address the challenges of global warming are not sufficient in this geographical region. Considering that agriculture is a relevant activity in most countries around this region, our study proposes to [...] Read more.
The Caribbean faces many environmental issues, and the mitigation and adaptation strategies to address the challenges of global warming are not sufficient in this geographical region. Considering that agriculture is a relevant activity in most countries around this region, our study proposes to enhance Caribbean waste management by transitioning to a sustainable and resilient process in the framework of a green, circular economy. The research has been focused on the thermochemical transformation of the typical residues of Caribbean farm products (plantain rachis, and cassava peel). Biochar samples were synthesized from these biomasses by the slow pyrolysis method at different temperatures (300 °C, 400 °C, and 500 °C). Biochar samples with a smooth surface were synthesized from plantain rachis biomass, while biochar samples with a porous surface were obtained from cassava peel biomass. At the same pyrolysis temperature, all biochar samples derived from plantain rachis exhibited higher production biochar yields than those biochar samples derived from cassava peel. The yield percentages were determined to be 65.7% and 62.0% at a pyrolysis temperature of 300 °C; 45.6% and 37.5% at 400 °C; and 33.7% and 25.4% at 500 °C, respectively. XRD measurements revealed that both biomass-derived biochar samples were found to be enriched with several compounds, such as kalicinite, arcanite, sylvite, CaO3Si, and MgO3Si, which vary according to the pyrolysis temperature. FTIR analysis revealed the presence of carbonyl and carboxyl functional groups on the surface of all biochar samples. However, only the aliphatic functional groups were observed on the surface of the biochar samples derived from cassava peel. These characteristics are of particular relevance due to their potential application in soil amendment or water remediation. Full article
(This article belongs to the Section Sustainable Processes)
Show Figures

Figure 1

25 pages, 1629 KiB  
Review
Biochemical Processes of Lignocellulosic Biomass Conversion
by Stanisław Ledakowicz
Energies 2025, 18(13), 3353; https://doi.org/10.3390/en18133353 - 26 Jun 2025
Viewed by 372
Abstract
After a brief characterisation of lignocellulosic biomass (LCB) in terms of its biochemical structure and the pretreatment techniques used to disrupt lignin structure and decrystallise and depolymerise cellulose, this review considers five main pathways for biochemical biomass conversion: starting with anaerobic digestion to [...] Read more.
After a brief characterisation of lignocellulosic biomass (LCB) in terms of its biochemical structure and the pretreatment techniques used to disrupt lignin structure and decrystallise and depolymerise cellulose, this review considers five main pathways for biochemical biomass conversion: starting with anaerobic digestion to convert various LCB feedstocks into bioproducts; considering the integration of biochemical and thermochemical processes, syngas fermentation, which has been recently developed for biofuel and chemical production, is reviewed; the production of 2G bioethanol and biobutanol from LCB waste is discussed; the literature on biohydrogen production by dark fermentation, photofermentation, and bioelectrochemical processes using microbial electrolysis cells as well as hybrid biological processes is reviewed. The conclusions and future prospects of integrating biochemical and thermochemical conversion processes of biomass are discussed and emphasised. Full article
Show Figures

Figure 1

18 pages, 2318 KiB  
Article
Renewable Energy from Cocoa Waste Biomass in Ecuador’s Coastal Region: Advancing Sustainable Supply Chains
by María Agustina Montesdeoca Chávez, Pierina Dayana Ruiz Zambrano, José Miguel Giler Molina and César Iván Álvarez Mendoza
Sustainability 2025, 17(13), 5827; https://doi.org/10.3390/su17135827 - 25 Jun 2025
Viewed by 682
Abstract
Coastal regions of Ecuador, particularly Esmeraldas and Manabí, face significant challenges related to energy access, waste management, and sustainable agricultural development. This study evaluates the renewable energy potential of cocoa waste biomass generated by smallholder farms in these provinces. A total of 20 [...] Read more.
Coastal regions of Ecuador, particularly Esmeraldas and Manabí, face significant challenges related to energy access, waste management, and sustainable agricultural development. This study evaluates the renewable energy potential of cocoa waste biomass generated by smallholder farms in these provinces. A total of 20 cocoa farms, either certified or in the process of certification under the Rainforest Alliance standard, were surveyed to quantify the volume of agricultural and agro-industrial residues. Residual biomass generation ranged from 50 to 6500 tons per year, depending on farm size, planting density, and management practices. Spatial analysis revealed that Esmeraldas holds the highest concentration of cocoa waste biomass, with some farms reaching a gross energy potential of up to 89.07 TJ/year. Using thermochemical conversion scenarios, effective energy potential was estimated, and 75% of the farms exceeded the viability threshold of 100 MWh/year. The results confirm the feasibility of cocoa biomass as a renewable energy source, mainly when managed collectively at the community level. Incorporating this waste into decentralized energy systems supports circular economy models, enhances energy self-sufficiency, and aligns with sustainable supply chain goals promoted by certification schemes. This study contributes to national efforts in energy diversification and provides a replicable model for integrating renewable energy into rural agricultural systems. Full article
Show Figures

Figure 1

27 pages, 870 KiB  
Review
Thermochemical Conversion of Sewage Sludge: Progress in Pyrolysis and Gasification
by Yibo Hu and Ziwei Chen
Water 2025, 17(12), 1833; https://doi.org/10.3390/w17121833 - 19 Jun 2025
Cited by 1 | Viewed by 696
Abstract
Sewage sludge, as a by-product of wastewater treatment, poses severe environmental challenges due to its high moisture, ash, and heavy metal content. Thermochemical conversion technologies, including pyrolysis and gasification, offer promising pathways for transforming sludge into valuable products such as bio-oil, biochar, and [...] Read more.
Sewage sludge, as a by-product of wastewater treatment, poses severe environmental challenges due to its high moisture, ash, and heavy metal content. Thermochemical conversion technologies, including pyrolysis and gasification, offer promising pathways for transforming sludge into valuable products such as bio-oil, biochar, and syngas. This paper systematically reviews recent advancements in pyrolysis and gasification, focusing on process optimization and catalyst development to enhance product quality and energy recovery. In pyrolysis, factors such as temperature, residence time, and heating rate significantly influence product yields and properties, while catalytic and co-pyrolysis approaches further improve product structure and reduce environmental risks. In gasification, parameters like the equivalence ratio, steam-to-sludge ratio, and catalyst application are key to enhancing syngas yield and quality, with biomass co-gasification offering additional benefits. Despite substantial progress, commercialization remains challenged by high operational costs, catalyst durability, and environmental impacts. Future research should emphasize improving sludge pretreatment, optimizing thermochemical processes, developing efficient and cost-effective catalysts, and addressing critical issues such as bio-oil quality, tar management, and syngas purification to promote the industrial application of these technologies. Full article
Show Figures

Figure 1

39 pages, 3650 KiB  
Review
Molten Salt Mixtures as an Energy Carrier for Thermochemical Processes of Renewable Gas Production: Review and Perspectives
by Marco D’Auria, Anna Chiara Tizzoni, Francesco Rovense, Salvatore Sau, Luca Turchetti, Diogo Canavarro, João Marchã, Pedro Horta and Michela Lanchi
Appl. Sci. 2025, 15(12), 6916; https://doi.org/10.3390/app15126916 - 19 Jun 2025
Viewed by 490
Abstract
This study provides a comprehensive review of molten salt technology, as well as electrochemical and thermochemical processes aimed at hydrogen and syngas production. First, this research illustrates the current types of molten salt mixtures, detailing their main applications and thermophysical properties. Then, the [...] Read more.
This study provides a comprehensive review of molten salt technology, as well as electrochemical and thermochemical processes aimed at hydrogen and syngas production. First, this research illustrates the current types of molten salt mixtures, detailing their main applications and thermophysical properties. Then, the analysis delves into existing thermo-electrochemical cycles and their specific operating conditions for producing hydrogen and syngas. Moreover, this study assesses the compatibility of these processes with molten salt integration. This investigation involved a comprehensive review of the existing technical and scientific literature, blending insights and practical experiences to offer detailed data on the topics explored. The findings suggest that molten salts, with their medium–high operating temperatures, can markedly improve the efficiency and sustainability of hydrogen and syngas production. Furthermore, this study outlines the pivotal role these technologies can play in achieving the European Union’s ambitious goals by enhancing the use of renewable energy sources and advancing the shift to carbon-free solutions. Full article
(This article belongs to the Special Issue Advanced Solar Energy Materials: Methods and Applications)
Show Figures

Figure 1

Back to TopTop