Advanced Bioenergy and Biofuel Technologies

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Biomass biomass	6.1	6.7	2021	19.3 Days	CHF 1200	Submit
Catalysts catalysts	4.5	8.3	2011	13.3 Days	CHF 2200	Submit
Energies energies	3.9	8.3	2008	16.7 Days	CHF 2600	Submit
Molecules molecules	5.1	10.3	1996	15.6 Days	CHF 2700	Submit
Processes processes	3.4	5.7	2013	14.7 Days	CHF 2400	Submit
Sustainability sustainability	4.1	8.9	2009	16.9 Days	CHF 2400	Submit

32 pages, 7525 KB

Open AccessArticle

Tracing Methanogenesis Pathways via Stable Carbon Isotopes for Sustainable Biogas Production in Continuous-Flow Open Systems

by Michał Bucha, Anna Detman-Ignatowska, Aleksandra Chojnacka, Ewa Łupikasza, Łukasz Pleśniak, Wojciech Drzewicki, Marta Jakubiak, Adriana Trojanowska-Olichwer, Beata Berbeć, Dominika Kufka, Anna Sikora and Mariusz Orion Jędrysek

Sustainability 2026, 18(13), 6880; https://doi.org/10.3390/su18136880 - 6 Jul 2026

Viewed by 265

Abstract

The common products of acidogenesis, the key stage in the process of anaerobic digestion, are lactate, butyrate, propionate, and acetate. They were decomposed in the Up-flow Anaerobic Sludge Blanket bioreactors working in continuous-flow open systems. A comprehensive analysis of variations in both isotopic [...] Read more.

The common products of acidogenesis, the key stage in the process of anaerobic digestion, are lactate, butyrate, propionate, and acetate. They were decomposed in the Up-flow Anaerobic Sludge Blanket bioreactors working in continuous-flow open systems. A comprehensive analysis of variations in both isotopic ratios and concentrations of organic acids in the effluents was conducted to enhance comprehension of methanogenic processes. The analysis of carbon isotope fractionation in the CO₂-CH₄ system, as evidenced by the α¹³C_CO2-CH4 factor, has indicated that acetate decarboxylation has occurred. Furthermore, a decline in CO₂ levels was observed, accompanied by the predominance of butyrate and propionate, despite the presence of acetic acid in the effluents from all the bioreactors. Butyric acid demonstrated the greatest resistance to decomposition, resulting in ¹³C-enrichment of DIC. Lactic acid was utilised almost entirely. The observations presented above were subsequently validated through statistical analysis. A comparative analysis of the δ¹³C(CH₄) and δ¹³C(CO₂) values of our study with those of other natural substrates (detritic lignite, xylite, maize silage, and cattle manure) was undertaken, and it was found that isotope fractionation differs significantly in closed (potential thermodynamic processes) and open systems (expected Rayleigh processes). In the context of open systems, the isotope fractionation factor α¹³C_CO2-CH4 during methaneogenesis has been observed to attain values that are consistent with those observed in CH₄ oxidation. The study revealed that the presence of acetate in the substrate (i.e., the M4 bioreactor) led to the generation of CO₂ with a higher proportion of light carbon isotopes. This, in turn, resulted in a shift in the isotope fractionation factor (i.e., α¹³C_CO2-CH4) to values below 1.03. Our results suggest that methanogenic pathway signatures in open, continuous-flow systems may only be partially apparent. This is because substrate depletion drives Rayleigh-type isotope enrichment, while the dominance of a single substrate and its constant inflow stabilise pathway expression and shift control towards substrate dynamics rather than intrinsic microbial changes. Our finding suggests that isotope-based diagnostics could enhance process control in biogas plants by identifying substrate-driven limitations and facilitating more efficient and stable CH₄ production. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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23 pages, 8678 KB

Open AccessArticle

Hydrogen Production from Municipal Solid Waste Gasification: Aspen Plus Simulation and Box–Behnken Optimisation

by Eliasu Ali and Satyanarayana Narra

Processes 2026, 14(11), 1839; https://doi.org/10.3390/pr14111839 - 5 Jun 2026

Viewed by 408

Abstract

Municipal Solid Waste (MSW) gasification presents a promising pathway for low-carbon bio-hydrogen production. However, MSW is underrepresented as a feedstock in the gasification literature due to its heterogeneity, and fewer studies have leveraged Box–Behnken experimental design in gasification simulation studies or investigated the [...] Read more.

Municipal Solid Waste (MSW) gasification presents a promising pathway for low-carbon bio-hydrogen production. However, MSW is underrepresented as a feedstock in the gasification literature due to its heterogeneity, and fewer studies have leveraged Box–Behnken experimental design in gasification simulation studies or investigated the interaction between equivalence ratio and steam–feed ratio. This paper develops a thermodynamic equilibrium model in Aspen Plus^® (V14) to simulate oxy-steam gasification of MSW derived from the Phyllis database, with subsequent optimisation using Box–Behnken Design. Sensitivity results confirm literature trends, with hydrogen yield generally increasing with gasification temperature and steam–feed ratio up to an optimum threshold, while an increasing equivalence ratio suppresses hydrogen formation. An optimum hydrogen volume fraction of 51.77% in the syngas composition was achieved at a gasification temperature of 873 °C, equivalence ratio of 0.3, and a steam-to-feedstock ratio of 0.5. The study revealed a comparatively smooth response surface between equivalence ratio and steam–feed ratio, and a statistically insignificant effect of equivalence ratio on hydrogen formation in steam gasification. This provides new insight into gasification systems, whereby, within the investigated equivalence ratio (ER) ranges of 0.2–0.4, steam can effectively drive hydrogen-enhancing reactions, thereby reducing the relative importance of oxygen supply in oxy-steam gasification. The study could provide useful guidance on experimental design for hydrogen production through steam gasification. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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43 pages, 4113 KB

Open AccessReview

Review of Selected Fuels Used and with Potential for Fueling Compression-Ignition Engines

by Karol Dębowski, Mirosław Karczewski and Tadeusz Dziubak

Energies 2026, 19(10), 2318; https://doi.org/10.3390/en19102318 - 12 May 2026

Viewed by 350

Abstract

This paper reviews selected biofuels that are currently in use, as well as fuels considered promising, for powering compression-ignition (CI) engines, including Common Rail systems. The review focuses on fuel properties, production pathways, operational compatibility, and the effects on engine performance and exhaust [...] Read more.

This paper reviews selected biofuels that are currently in use, as well as fuels considered promising, for powering compression-ignition (CI) engines, including Common Rail systems. The review focuses on fuel properties, production pathways, operational compatibility, and the effects on engine performance and exhaust emissions. The objective is to systematize the current state of knowledge on biodiesel, hydrotreated vegetable oil (HVO), biomass-to-liquid (BtL), F-34, and sustainable aviation fuel (SAF), and to identify their key advantages, implementation constraints, and research gaps relevant to transport and power-generation applications. The paper compiles and compares published studies on fuel production routes and on the consequences of fuel use in CI engines with respect to performance and pollutant emissions. As an outcome, the available evidence is synthesized, fuels with the highest implementation potential are indicated in the context of emission reduction while maintaining required operational functionality, and priority areas for further research are highlighted, including the still insufficiently characterized effects of SAF on CI engine operation and emissions. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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20 pages, 7364 KB

Open AccessArticle

Optimizing Biodiesel Synthesis: From Process Parameters to the Distinct and Sub-Additive Effects of Water and Iron in Supercritical Methanol

by Ke Zhang, Zhigang Que, Jie Luo, Yinxuan Fu, Xiaodi Cheng, Rong Huang, Fan Gu and Xianhua Qiu

Processes 2026, 14(9), 1498; https://doi.org/10.3390/pr14091498 - 6 May 2026

Viewed by 307

Abstract

Biodiesel is a promising green and renewable fuel that can replace fossil fuels and reduce greenhouse gas emissions. The effects of reaction temperature (200–290 °C), residence time (0–75 min), and methanol-to-oleic acid molar ratio (6:1–35:1) on the esterification of oleic acid with supercritical [...] Read more.

Biodiesel is a promising green and renewable fuel that can replace fossil fuels and reduce greenhouse gas emissions. The effects of reaction temperature (200–290 °C), residence time (0–75 min), and methanol-to-oleic acid molar ratio (6:1–35:1) on the esterification of oleic acid with supercritical methanol were investigated in a batch reactor. Furthermore, orthogonal experiments were designed to explore the optimal reaction conditions. and the influences of H₂O (0–33.3 wt%) and Fe (0–20.0 wt%) contents were examined. Results showed that the conversion of oleic acid to methyl oleate exhibited a volcano-type dependence on both temperature and molar ratio, peaking at 250 °C and a ratio of 15:1, respectively. Conversion initially increased with residence time, then plateaued around 30 min. Under the optimal conditions of 250 °C, 30 min, and a 15:1 molar ratio, the conversion reached 76.8%. Both additives enhanced conversion at low loadings (≤5.0 wt%). However, higher water content inhibited conversion, whereas the promotional effect of Fe saturated beyond 5.0 wt%. The co-addition of 5.0 wt% water and 5.0 wt% Fe yielded a positive but sub-additive effects: conversion exceeded that with water alone but remained lower than with Fe alone. These findings contribute to advancing the high-efficiency and low-cost production of biodiesel. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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25 pages, 2386 KB

Open AccessArticle

A Supply Chain Framework for Corn Products in Sumenep to Support Sustainable Ethanol Production

by Sabarudin Akhmad, Muhammad Azmi Alamsyah, Rifky Maulana Yusron and Anis Arendra

Sustainability 2026, 18(9), 4534; https://doi.org/10.3390/su18094534 - 5 May 2026

Viewed by 650

Abstract

Indonesia’s E10 blending mandate presents a strategic opportunity for decarbonization and inclusive rural development, contingent on a robust supply chain integrating smallholder farmers. This study developed a novel supply chain framework for corn products in Sumenep to facilitate sustainable ethanol production. Methods involved [...] Read more.

Indonesia’s E10 blending mandate presents a strategic opportunity for decarbonization and inclusive rural development, contingent on a robust supply chain integrating smallholder farmers. This study developed a novel supply chain framework for corn products in Sumenep to facilitate sustainable ethanol production. Methods involved comprehensive data collection, mathematical modeling using the p-median method, and farmer clustering techniques. Findings reveal that Sumenep Regency’s substantial corn harvest of 8,475,914.5 tons, yielding 1,271,387.175 tons of kernels, can produce 381,416.1525 L of bioethanol. By applying a clustering supply chain model, the farmers’ group profit is IDR 205,693,725,826, while it is IDR 177,394,823,353 for the non-clustering model, meaning that the clustering supply chain model increases profit by 16% compared to the model without clustering. This localized production, enabled by a simplified, decentralized supply chain architecture, significantly enhances national energy security, reduces greenhouse gas emissions, and improves the economic stability of smallholder farmers through equitable value capture and minimized logistical costs. The framework offers a practical, implementable strategy for Indonesia’s energy transition, fostering environmental sustainability and inclusive socio-economic development. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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31 pages, 7511 KB

Open AccessArticle

Synergistic Analysis of Methanol–Diesel Combustion for a Marine Diesel Engine: An Integrated CFD and Experimental Method

by Zixiao Ye, Ke Chen, Jialiang Huang, Zibin Yin, Peicun Zhang, Yuchen Liu, Jinyu Fan and Zhiqing Zhang

Energies 2026, 19(7), 1794; https://doi.org/10.3390/en19071794 - 7 Apr 2026

Viewed by 591

Abstract

With the growth of global maritime transportation volume and fuel shortages caused by excessive oil consumption, energy conservation and emission reduction technologies for marine diesel engines have become a core research focus. A three-dimensional (3D) CFD model of a methanol–diesel dual-fuel marine diesel [...] Read more.

With the growth of global maritime transportation volume and fuel shortages caused by excessive oil consumption, energy conservation and emission reduction technologies for marine diesel engines have become a core research focus. A three-dimensional (3D) CFD model of a methanol–diesel dual-fuel marine diesel engine was developed in AVL-FIRE and coupled with a CHEMKIN reaction mechanism. The model was validated against experimental data, with errors in cylinder pressure, heat release rate, and major emissions below 5%. Based on the validated model, the effects of the methanol blending ratio (0–30%), injection advance angle, intake temperature, intake pressure, and EGR rate on combustion and emissions were investigated. The results show that increasing the methanol blending ratio reduced cylinder pressure, in-cylinder temperature, and NO and soot emissions, while increasing the peak heat release rate. Advancing injection timing improved combustion and reduced CO and soot emissions but increased NO formation. Higher intake temperature worsened combustion performance and increased NO, CO, and soot emissions. Orthogonal analysis and regression-based optimization identified an optimal condition with a methanol blending ratio of 27%, an EGR of 12.5%, an injection advance angle of 21.2 °CA, an intake temperature of 319.05 K, and an intake pressure of 0.223 MPa. Under this condition, the NOx mass fraction was 1.65 × 10⁻⁵. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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24 pages, 5060 KB

Open AccessArticle

Effects of Pyrolysis Carbonization Time of Corn Stalks on Microbial Communities in Biogas Production with Livestock and Poultry Manure as Fermentation Substrate

by Su Wang, Pengfei Li, Yujun Bao, Zhanjiang Pei, Shiwen Liang, Xianfeng Yang and Fengmei Shi

Energies 2026, 19(7), 1614; https://doi.org/10.3390/en19071614 - 25 Mar 2026

Viewed by 480

Abstract

In the process of anaerobic digestion for manure treatment, adding conductive materials is one of the most used methods to enhance methane yield. Biochar, a stable conductive material, shows significant potential in facilitating direct interspecies electron transfer in anaerobic digestion systems. However, biochar’s [...] Read more.

In the process of anaerobic digestion for manure treatment, adding conductive materials is one of the most used methods to enhance methane yield. Biochar, a stable conductive material, shows significant potential in facilitating direct interspecies electron transfer in anaerobic digestion systems. However, biochar’s structure and properties are influenced by its preparation method, and the mechanisms by which structural characteristics affect methane yield and microbial community structure in fermentation systems require further investigation. This study investigates the effects of pyrolysis duration (1 h for A3O and 2 h for A3T) at 550 °C using corn straw as raw material. Through characterization analyses including SEM, FTIR, conductivity, and elemental composition, we explore the impacts on gas production efficiency and key parameters in anaerobic digestion systems. By analyzing microbial community structure and changes in methanogenic functional bacteria, we elucidate the mechanisms by which biochar materials with different pyrolysis times influence anaerobic digestion processes and microbial community composition. These findings provide theoretical foundations and support for optimizing biochar preparation techniques and their targeted applications in anaerobic digestion fields. It was found that the biochar-treated group exhibited higher methane production. Compared with the CK group without biochar, the methane production of A3O and A3T increased by 8.53% and 5.16%, respectively. While methane yield differed little between A3O and A3T, longer pyrolysis time increased the biochar’s specific surface area, promoting the system’s reaction rate and enabling faster methanogenesis. High-throughput analysis showed that biochar enriched methanogenic archaea like Methanosarcina and Methanobrevibacter while upregulating methanogenesis metabolic pathways and enhancing system metabolic potential. This study elucidates the influence of pyrolysis conditions on biochar performance and its regulatory role in anaerobic digestion, providing a basis for energy recovery from organic waste and biochar application in anaerobic fermentation. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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27 pages, 5933 KB

Open AccessArticle

Modeling and Performance Analysis of a Solar Energy and Above-Ground Biogas Digester Complementary Coupling Energy Supply System

by Lei Fang, Miao Luo, Ting Xu and Xiaofei Zhen

Energies 2026, 19(5), 1267; https://doi.org/10.3390/en19051267 - 3 Mar 2026

Viewed by 449

Abstract

Rural households in cold regions still rely heavily on coal for cooking and domestic hot water, while single renewable energy sources suffer from intermittency and limited system-level assessment. This study proposes a solar–biogas complementary energy supply system integrating evacuated-tube solar collectors, an above-ground [...] Read more.

Rural households in cold regions still rely heavily on coal for cooking and domestic hot water, while single renewable energy sources suffer from intermittency and limited system-level assessment. This study proposes a solar–biogas complementary energy supply system integrating evacuated-tube solar collectors, an above-ground anaerobic digester, thermal storage, and biogas utilization for rural residential applications in Minqin, Northwest China. A dynamic system-wide model was developed by coupling TRNSYS with nonlinear representations of anaerobic fermentation and biogas boilers, enabling hour-by-hour simulation of energy production, conversion, storage, and consumption. Field measurements were used for validation, and the root mean square deviation between simulated and measured temperatures and gas production remained below 10%. During the heating season, the solar subsystem supplied 10% of the digester heating demand and 90% of the domestic hot-water load, while the biogas subsystem contributed 9.29% and 90.71%, respectively. The system delivered 4728.96 MJ of heat against a seasonal demand of 4636.22 MJ, fully meeting user requirements. A comprehensive 3E (energy–environment–economic) assessment shows that, compared with traditional rural energy supply modes, the proposed system reduces CO₂ and NOx emissions by 65.85% and 98.13%, respectively, and demonstrates favorable economics with a benefit–cost ratio of 2.41 and a discounted payback period of 3.27 years. The proposed modeling and evaluation framework provides a replicable solution for clean energy substitution and circular waste utilization in rural areas. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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15 pages, 1176 KB

Open AccessArticle

Financial Potential of Life Cycle Assessment of Production of Biofuels via Hydrothermal Liquefaction Using Microalgae in Cement Industry

by David Ocampo Echeverri, Victoria V. Beltrán, Alejandro Pérez Mesa, Luis A. Ríos and Esteban Ocampo Echeverri

Energies 2026, 19(5), 1153; https://doi.org/10.3390/en19051153 - 26 Feb 2026

Cited by 1 | Viewed by 560

Abstract

This study presents a comprehensive life cycle assessment of the production of biofuels from microalgae by hydrothermal liquefaction, focusing on the valorization of CO₂ emitted by the cement industry, which represents about 8% of global anthropogenic emissions. The results demonstrate that hydrothermal [...] Read more.

This study presents a comprehensive life cycle assessment of the production of biofuels from microalgae by hydrothermal liquefaction, focusing on the valorization of CO₂ emitted by the cement industry, which represents about 8% of global anthropogenic emissions. The results demonstrate that hydrothermal liquefaction is a promising option for producing biofuels and highlight the importance of understanding its environmental impact in order to ensure its sustainability. OpenLCA 2.6 software was used to analyze the greenhouse gas (GHG) emissions associated with the process, and it was found that it can capture 3.91 kg of CO₂ per kg of biofuel produced compared to 0.286 kg of CO₂ per kg of fuel emitted by petrochemical diesel. This article also discusses the financial potential of the technology through the reduction in capital costs due to the elimination of taxes and tariffs under the current policies in Colombia, including the benefits of carbon credits, and finds that the classification of these processes as environmental facilitates their implementation at the industrial level. In conclusion, the capital investment can be reduced by about 15% with an estimated MUSD 165, and the project would be profitable, producing around 850 barrels/day of biofuel under a medium scenario with a carbon bond price of 5 USD/ton CO₂, capturing an estimated 20% of the CO₂ emitted at the Cementos Argos plant in Cartagena, Colombia. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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29 pages, 4821 KB

Open AccessArticle

Production of SNG from Biomass Using a Commercial-Scale Fluidized Bed Gasifier Integrated with Water Electrolysis

by Tomasz Marcin Chmielniak, Tadeusz Jan Chmielniak, Tomasz Iluk, Tomasz Billig and Leszek Stepien

Energies 2026, 19(1), 253; https://doi.org/10.3390/en19010253 - 2 Jan 2026

Viewed by 1144

Abstract

Biomass gasification, as a thermochemical process, has attracted growing interest due to the increasing popularity of biofuel production based on syngas or pure hydrogen. Moreover, when integrated with CO₂ capture, this method of producing gaseous fuels can achieve negative CO₂ emissions, [...] Read more.

Biomass gasification, as a thermochemical process, has attracted growing interest due to the increasing popularity of biofuel production based on syngas or pure hydrogen. Moreover, when integrated with CO₂ capture, this method of producing gaseous fuels can achieve negative CO₂ emissions, making it competitive with other production systems based on either fossil or renewable sources. This paper presents the results of a process and economic analysis of synthetic natural gas (SNG) production systems integrated with a commercial fluidized-bed gasification reactor based on Synthesis Energy Systems (SES) technology. The study examines the potential integration of the system with a water electrolyzer at two levels of coupling: one providing oxygen for the gasification process, and the other eliminating the need for CO₂ separation before the SNG synthesis stage. Using a single gasification unit with a raw biomass feed rate of 60 t/h, the system produces 188 t/d of SNG. Integration with a water electrolyzer increases SNG production to 259 and 621 t/d. For cases without electrolyzer integration and under the assumption of zero emissions from biomass processing, the application of CO₂ separation enables the achievement of negative CO₂ emissions. This creates an opportunity for additional revenue from the sale of CO₂ emission allowances, which can significantly reduce SNG production costs. In this analysis, the break-even CO₂ price, above which the SNG production cost becomes negative, is USD 251/t CO₂. In systems integrated with water electrolysis, the cost and carbon footprint of the electricity consumed in the electrochemical water-splitting process have a decisive impact on both the overall SNG production cost and its carbon intensity. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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19 pages, 1420 KB

Open AccessArticle

Optimization, Economic Assessment, and Quality Analyses of Waste-Based Biodiesel Fuel Production: A Case Study of Waste Cooking Oil and a Seashell Synthesized Catalyst

by Anietie Okon Etim and Joseph K. Bwapwa

Energies 2026, 19(1), 48; https://doi.org/10.3390/en19010048 - 22 Dec 2025

Cited by 1 | Viewed by 1258

Abstract

Valorization of environmental waste into sustainable energy and value-added products offers a strategic pathway for advancing circular economic development and resource sustainability. In this study, waste cooking oil was converted into biodiesel using biogenically generated CaO, prepared thermally at 900 °C. The reaction [...] Read more.

Valorization of environmental waste into sustainable energy and value-added products offers a strategic pathway for advancing circular economic development and resource sustainability. In this study, waste cooking oil was converted into biodiesel using biogenically generated CaO, prepared thermally at 900 °C. The reaction process was modeled and optimized with a Taguchi orthogonal array L9(3⁴), considering four factors at three levels to yield nine experimental conditions. The model reliability was statistically validated through analysis of variance (ANOVA) at 95% confidence level (p < 0.05), achieving a high determination coefficient (R²) of 0.9965. The maximum biodiesel yield of 91.08% was obtained under the optimal conditions of the methanol to oil ratio of 15:1, a catalyst loading of 4.5 wt%, a reaction time of 90 min, a temperature of 65 °C, and a constant stirring speed of 650 rpm. The fuel property analysis confirmed compliance with international biodiesel and diesel standards). Economic evaluation of the process showed that integrating waste cooking oil with reusable seashell-derived catalysts enabled the production of high-quality biodiesel at R23.20 (~USD 1.39)/L, highlighting a sustainable and cost-competitive alternative to conventional feedstock. The study contributes to advancing waste-to-energy technologies and supports the transition towards a circular and sustainable energy future. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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17 pages, 2000 KB

Open AccessArticle

Comparative Experimental Study on Hydrolysis of Cellulose by Plasma Acid

by Weidong Zhao, Yi Sun, Weijun Zhang, Yongsheng Fan and Junfeng Wang

Processes 2025, 13(12), 3890; https://doi.org/10.3390/pr13123890 - 2 Dec 2025

Viewed by 1048

Abstract

The key technological step in realizing the energy utilization of cellulose lies in the hydrolysis of cellulose into glucose. To achieve clean and efficient energy utilization of cellulose, this study innovatively proposes a technical approach of plasma acid synchronous catalytic hydrolysis of cellulose, [...] Read more.

The key technological step in realizing the energy utilization of cellulose lies in the hydrolysis of cellulose into glucose. To achieve clean and efficient energy utilization of cellulose, this study innovatively proposes a technical approach of plasma acid synchronous catalytic hydrolysis of cellulose, which breaks through the limitations of conventional stepwise acid-production hydrolysis and enables the simultaneous generation of acid and hydrolysis of cellulose within the same reaction system. The effects of operating voltage, discharge gap, and reaction time on hydrolysis efficiency were systematically investigated, and a comparative study was conducted on the hydrolysis performance between the synchronous method and the two-step method. The results indicate that within the same reaction duration, the synchronous method demonstrates a significantly higher cellulose conversion rate. Specifically, at a reaction time of 60 min, the average conversion rate of the synchronous method is approximately 32.8% higher than that of the two-step method, while the average specific energy consumption is only 16.7% of the latter. Mechanism analysis reveals that the high-energy electrons and H⁺ generated by plasma discharge effectively facilitate efficient energy transfer to cellulose molecules, significantly reducing the activation energy of the hydrolysis reaction. This process accelerates the efficient release of glucose units, thereby enabling faster hydrolysis at lower energy consumption. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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21 pages, 7819 KB

Open AccessArticle

Multiway Analysis of the Electrochemical Oxidation Pathway of a Lignin Using Chemometrics

by Gobind Sah, John A. Staser and Peter B. Harrington

Molecules 2025, 30(21), 4305; https://doi.org/10.3390/molecules30214305 - 5 Nov 2025

Viewed by 1079

Abstract

The electrochemical oxidation mechanism of biopolymer lignin is challenging to characterize due to its complex structure. Controlling the oxidation process is crucial for ensuring the economic feasibility of electrochemical depolymerization of lignin, as it often generates numerous undesirable compounds. Regulating the depolymerization process [...] Read more.

The electrochemical oxidation mechanism of biopolymer lignin is challenging to characterize due to its complex structure. Controlling the oxidation process is crucial for ensuring the economic feasibility of electrochemical depolymerization of lignin, as it often generates numerous undesirable compounds. Regulating the depolymerization process can lead to the production of high-yield aromatic compounds, such as phenols and carboxylic acids. In addition to the depolymerization of lignin by the electrocatalyst, hydroxyl radicals (^•OH) during the electrochemical oxidation could also depolymerize lignin. Previous studies have reported that ^•OH forms during electrochemical oxidation; however, it is still uncertain whether these radicals or electrocatalysts are responsible for depolymerizing lignin. This study investigates the pivotal issue of whether the depolymerization process is driven by ^•OH or by a direct electrochemical route. In this study, lignin compounds were electrochemically oxidized using a nickel-cobalt (Ni-Co) electrocatalyst at several electrode potentials, and the oxidized products were analyzed using headspace solid-phase micro-extraction gas chromatography–mass spectrometry (SPME-GC-MS) and factor analysis (FA). Electrochemical depolymerization of lignin yielded mainly phenolic compounds (e.g., tert-butyl phenols), phthalate esters (e.g., dibutyl phthalate, bis(2-methylpropyl) phthalate), furan derivatives (e.g., 2-butyltetrahydrofuran), and short-chain carboxylic acid esters. This work has successfully predicted that both electrocatalyst and ^•OH radicals contribute to the electrochemical depolymerization of lignin. Radical-mediated depolymerization yielded a broader range of products. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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22 pages, 1099 KB

Open AccessReview

Synergistic Conversion and Catalytic Upgrading of Seaweed Biomass for Sustainable Bioenergy: Advances, Challenges, and Future Prospects

by Qing Xu, Shenwei Zhang and Shengxian Xian

Catalysts 2025, 15(11), 1008; https://doi.org/10.3390/catal15111008 - 24 Oct 2025

Cited by 2 | Viewed by 2315

Abstract

Seaweed holds significant promise as a renewable feedstock for bioenergy due to its rapid growth, carbon sequestration capacity, and non-competition with terrestrial agriculture. This review examines recent progress in multi-method synergies for optimized energy conversion from seaweed biomass. Physical pre-treatments (e.g., drying, milling, [...] Read more.

Seaweed holds significant promise as a renewable feedstock for bioenergy due to its rapid growth, carbon sequestration capacity, and non-competition with terrestrial agriculture. This review examines recent progress in multi-method synergies for optimized energy conversion from seaweed biomass. Physical pre-treatments (e.g., drying, milling, ultrasound, microwave) enhance substrate accessibility but face energy intensity constraints. Chemical processes (acid/alkali, solvent extraction, catalysis) improve lipid/sugar recovery and bio-oil yields, especially via hydrodeoxygenation (HDO) and catalytic cracking over tailored catalysts (e.g., ZSM-5), though cost and byproduct management remain challenges. Biological methods (enzymatic hydrolysis, fermentation) enable eco-friendly valorization but suffer from scalability and enzymatic cost limitations. Critically, integrated approaches—such as microwave-solvent systems or hybrid thermochemical-biological cascades—demonstrate superior efficiency over singular techniques. Upgrading pathways for liquid bio-oil (e.g., HDO, catalytic pyrolysis) show considerable potential for drop-in fuel production, while solid-phase biochar and biogas offer carbon sequestration and circular economy benefits. Future priorities include developing low-cost catalysts, optimizing process economics, and scaling synergies like hydrothermal liquefaction coupled with catalytic upgrading to advance sustainable seaweed biorefineries. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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22 pages, 2265 KB

Open AccessArticle

Utilization of Low-Viscosity Sustainable Quaternary Microemulsification Fuels Containing Waste Frying Oil–Diesel Fuel–Bio-Alcohols in a Turbocharged-CRDI Diesel Engine

by Huseyin Sanli

Sustainability 2025, 17(19), 8835; https://doi.org/10.3390/su17198835 - 2 Oct 2025

Viewed by 1143

Abstract

In this study, low-viscosity (<5 mm²·s⁻¹, fits European Biodiesel Standard-EN 14214) quaternary microemulsification fuels were developed and tested in a CRDI diesel engine to evaluate their effects on engine performance, injection, combustion, and emission characteristics. The fuels were formulated [...] Read more.

In this study, low-viscosity (<5 mm²·s⁻¹, fits European Biodiesel Standard-EN 14214) quaternary microemulsification fuels were developed and tested in a CRDI diesel engine to evaluate their effects on engine performance, injection, combustion, and emission characteristics. The fuels were formulated using 50% petro-diesel, 30% waste frying oil (without converting biodiesel), and a combination of 10% n-butanol with either 10% methanol or 10% ethanol. Engine tests were conducted at constant speed of 2000 rpm and five different engine loads. The results indicated that both microemulsified fuels exhibited increased brake specific fuel consumption by about 20% and brake specific energy consumption by around 8% compared to petro-diesel, while thermal efficiency decreased by about 8%. Injection timing for both pilot and main injections occurred earlier with the emulsification fuels, and higher injection amount and injection rate values were observed at all loads. As engine load increased, the peak cylinder pressures of the emulsified fuels surpassed those of petro-diesel, although the crank angles at which these peak values were attained were similar. The combustion duration was shorter for both quaternary fuels, with similar maximum pressure rise rates to petro-diesel. Emulsification fuels caused higher exhaust emissions (especially THC) and this difference increased with increasing load. When comparing two formulations, the methanol-containing fuel demonstrated slightly better results than the ethanol-containing blend. These findings suggest that microemulsified fuels containing bio-alcohols and waste frying oil can be sustainable fuel alternatives for partial petro-diesel substitution if the injection settings are adapted in accordance with the properties of these fuels. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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28 pages, 4768 KB

Open AccessArticle

Biogas and Hydrogen Production from Waste Biomass via Dark Fermentation Evaluating VFAs, COD, and HRT for Process Optimization

by Hoe-Gil Lee and Zachary Dulany

Biomass 2025, 5(3), 57; https://doi.org/10.3390/biomass5030057 - 18 Sep 2025

Cited by 8 | Viewed by 2980

Abstract

Biomass energy transforms waste into biofuels and supports water purification. This study examines enhanced hydrogen production via dark fermentation, tracking volatile fatty acids (VFAs), chemical oxygen demand (COD), carbohydrates, and hydraulic retention time (HRT) to optimize biogas yield and quality. Investigations into acidogenesis [...] Read more.

Biomass energy transforms waste into biofuels and supports water purification. This study examines enhanced hydrogen production via dark fermentation, tracking volatile fatty acids (VFAs), chemical oxygen demand (COD), carbohydrates, and hydraulic retention time (HRT) to optimize biogas yield and quality. Investigations into acidogenesis and acetogenesis explore methods for breaking down long-chain VFAs into short-chain VFAs, which are critical for efficient hydrogen generation. Testing and analysis of VFAs, carbonates, COD, and HRT provide insights into bacterial activity that drives hydrogen production. The main VFAs produced were acetic, propionic, and butyric acids. DF1 and DF2 primarily generated acetic acid, consistent with cheese whey (CW)-based fermentations. DF1.1, using 5× diluted CW and a 30:70 inoculum-to-substrate ratio (I2SR), exhibited elevated butyric acid levels, similar to those observed with food waste. The first dark fermentation process (DF1) initially showed effective carbohydrate metabolism but later experienced spikes in succinic and lactic acids, which reduced hydrogen production. In contrast, the second dark fermentation process (DF2) maintained low lactic acid levels and increased acetate concentrations, indicating improved system performance. DF1.1 also demonstrated stable VFA production and lactic acid reduction. Greater CW dilution, higher initial pH, and increased HRT were key factors in minimizing acidification and enhancing hydrogen-producing pathways. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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17 pages, 1924 KB

Open AccessArticle

Conversion of Furfural as a Bio-Oil Model Compound over Calcium-Based Materials as Sacrificial Low-Cost Catalysts for Bio-Oil Upgrading

by Moritz Böhme, Peter A. Jensen, Martin Høj, Brian B. Hansen, Magnus Z. Stummann and Anker D. Jensen

Catalysts 2025, 15(6), 554; https://doi.org/10.3390/catal15060554 - 3 Jun 2025

Cited by 4 | Viewed by 1859

Abstract

The stabilization and upgrading of biomass and waste-derived pyrolysis oils requires development of reliable, active and low-cost upgrading catalysts. Basic natural materials can act as such catalysts and convert reactive oxygenates present in biomass pyrolysis oils. The conversion of furfural as a model [...] Read more.

The stabilization and upgrading of biomass and waste-derived pyrolysis oils requires development of reliable, active and low-cost upgrading catalysts. Basic natural materials can act as such catalysts and convert reactive oxygenates present in biomass pyrolysis oils. The conversion of furfural as a model compound has been conducted in an autoclave reactor at 200 °C to 300 °C using different calcium-based materials. CaCO₃, Ca(OH)₂, CaO, cement raw meal (CRM) and calcined cement raw meal (cCRM) were screened for their catalytic activity and characterized using X-ray powder diffraction (XRD) and X-ray fluorescence (XRF), nitrogen physisorption, carbon dioxide temperature programmed desorption (CO₂-TPD) and thermogravimetric analysis (TGA). CaCO₃ and CRM had low basicity and showed no catalytic activity at 200 to 300 °C. Notably, 90% conversion of furfural was achieved at 200 °C using Ca(OH)₂ with products being mostly furfural di- and trimers. For the basic CaO and cCRM, a temperature of 250 °C or above caused rapid polymerization of furfural. The proposed mechanism follows the Cannizzaro reaction of furfural, catalyzed by basic sites, polymerization of furfuryl alcohol, decarboxylation of furoic acid and decarbonylation of furfural, releasing CO, CO₂ and H₂O. Calcined cement raw meal showed the most promise for application as low-cost, sacrificial, basic catalyst. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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14 pages, 3084 KB

Open AccessArticle

Catalytic Hydrodeoxygenation of Pyrolysis Volatiles from Pine Nut Shell over Ni-V Bimetallic Catalysts Supported on Zeolites

by Yujian Wu, Xiwei Xu, Xudong Fan, Yan Sun, Ren Tu, Enchen Jiang, Qing Xu and Chunbao Charles Xu

Catalysts 2025, 15(5), 498; https://doi.org/10.3390/catal15050498 - 20 May 2025

Cited by 1 | Viewed by 1371

Abstract

Bio-oil is a potential source for the production of alternative fuels and chemicals. In this work, Ni-V bimetallic zeolite catalysts were synthesized and evaluated in in situ catalytic hydrodeoxygenation (HDO) of pyrolysis volatiles of pine nut shell for upgraded bio-oil products. The pH [...] Read more.

Bio-oil is a potential source for the production of alternative fuels and chemicals. In this work, Ni-V bimetallic zeolite catalysts were synthesized and evaluated in in situ catalytic hydrodeoxygenation (HDO) of pyrolysis volatiles of pine nut shell for upgraded bio-oil products. The pH and lower heating value (LHV) of the upgraded bio-oil products were improved by in situ catalytic HDO, while the moisture content and density of the oil decreased. The O/C ratio of the upgraded bio-oil products decreased significantly, and the oxygenated compounds in the pyrolysis volatiles were converted efficiently via deoxygenation over Ni-V zeolite catalysts. The highest HDO activity was obtained with NiV/MesoY, where the obtained bio-oil had the lowest O/C atomic ratio (0.27), a higher LHV (27.03 MJ/kg) and the highest selectivity (19.6%) towards target arenes. Owing to the more appropriate pore size distribution and better dispersion of metal active sites, NiV/MesoY enhanced the transformation of reacting intermediates, obtaining the dominant products of phenols and arenes. A higher HDO temperature improved the catalytic activity of pyrolysis volatiles to form more deoxygenated arenes. Higher Ni loading could generate more metal active sites, thus promoting the catalyst’s HDO activity for pyrolysis volatiles. This study contributes to the development of cost-efficient and eco-friendly HDO catalysts, which are required for producing high-quality biofuel products. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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22 pages, 1205 KB

Open AccessReview

Integrated Approach for Biomass Conversion Using Thermochemical Routes with Anaerobic Digestion and Syngas Fermentation

by Dolores Hidalgo, Ana Urueña, Jesús M. Martín-Marroquín and David Díez

Sustainability 2025, 17(8), 3615; https://doi.org/10.3390/su17083615 - 16 Apr 2025

Cited by 33 | Viewed by 5146

Abstract

This review focuses on the integration of thermochemical and biochemical processes as a transformative approach to biomass conversion. By combining technologies such as anaerobic digestion, hydrothermal liquefaction, pyrolysis, and syngas fermentation, this review highlights how hybrid systems maximize resource recovery and improve energy [...] Read more.

This review focuses on the integration of thermochemical and biochemical processes as a transformative approach to biomass conversion. By combining technologies such as anaerobic digestion, hydrothermal liquefaction, pyrolysis, and syngas fermentation, this review highlights how hybrid systems maximize resource recovery and improve energy efficiency. Key examples include the use of digestate from anaerobic digestion as a feedstock for pyrolysis or hydrothermal carbonization, enhancing biochar and hydrochar production while improving nutrient recycling. Similarly, the integration of syngas fermentation with gasification demonstrates how thermochemical products can be further valorized into biofuels under milder biochemical conditions. This review also addresses the reuse of by-products, such as the aqueous phase from hydrothermal processes, in nutrient recovery and algae cultivation, showcasing the circular potential of these systems. By emphasizing the technical and economic synergies of integrating diverse technologies, this paper outlines a clear pathway for industrial-scale adoption, contributing to sustainable energy production and reduced greenhouse gas emissions. Full article

(This article belongs to the Topic Advanced Bioenergy and Biofuel Technologies)

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