Search Results (383)

Most nations are shifting towards renewable energy sources to reduce energy-related emissions and achieve their net zero emissions targets by mid-century. Consequently, many attempts have been made to invest in clean, accessible, inexpensive, sustainable and reliable renewable energy sources while reducing dependency on fossil fuels. Recently, the production of biogas and upgrading it to produce biomethane is considered a sustainable way to reduce emissions from natural gas consumption. However, uncertainties in the biomass supply chain and less attention to decarbonising the natural gas grid have led to fewer investors in biomethane injection projects. Thus, researchers have applied Geographic Information System (GIS) as the best decision-making tool with spatial analytical and optimisation capabilities to address this issue. This study aims to review GIS-based applications on planning and optimising the biomass supply chain. Accordingly, this review covers different GIS-based biomass assessment methods with the evaluation of feedstock types, GIS-based approaches on selecting and optimising bioenergy plant locations and GIS-based applications on facilitating biomethane injection projects. This review identified four major biomass assessment approaches: Administrative division-based, location-based, cluster-based and grid-based. Sustainability criteria involved in site selection were also discussed, along with suitability and optimality techniques. Most of the optimising studies investigated cost optimisation based on a single objective. However, optimising the whole supply chain, including all operational components of the biomass supply chain, is still seldom investigated. Furthermore, it was found that most studies focus on site selection and logistics, neglecting biomethane process optimisation. Full article

Addressing the agricultural challenges of agri-food waste accumulation, this study assessed the energy potential of green residues from tomato (Solanum lycopersicum L. cv. Kmicic) plants in different fertilizer configurations and Shea nutshell (Vitellaria paradoxa) waste. Two key parameters were compared: (I) Calorific Value (CV), representing thermal treatment, and (II) Biogas and Biomethane production potential, representing biochemical treatment. Potential was estimated using the Baserga method and the fermentable organic matter (FOM) method. Additionally, the effect of tomato fertilization on the elemental composition and energy potential of its waste was analyzed. Shea waste showed better properties for both thermal and biochemical utilization, with a CV of 16.29 MJ/kg. The Baserga and FOM methods of estimation showed that the highest Biogas yields from Shea waste were 504.18 and 671.39 L_N/kg DM, respectively. Among fertilized tomato residues, volcanic tuff fertilizer additive resulted in an optimal C/N ratio (28.41) and a high Biogas production potential of 457.13 L_N/kg DM (Baserga) and 542.85 L_N/kg DM (FOM). These findings demonstrate the feasibility of employing tomato waste and Shea waste as promising feedstock for energy production. Full article

Peracetic acid (PAA) oxidation, which is a kind of chemical method for sludge pretreatment, has been verified to be valid for promoting sludge anaerobic digestion performance. However, the methane production is still limited at certain levels by this method, because excess PAA has negative effects on methanogens. This work selected a freezing method combined with PAA to form a composite sludge pretreatment technology for synergistically improving the biomethane production. According to the experimental data, the methane yield was largely enhanced from 166.4 ± 5.6 mL/g volatile suspended solids (VSS) in the control to 261.5 ± 7.3 mL/g VSS by the combined freezing (−10 °C) and PAA (0.08 g/g TSS) pretreatment, with a 57.2% increase rate. Kinetic analysis showed that the methane production potential, methane production rate, and hydrolysis rate were promoted, respectively, from 159.4 mL/g VSS, 17.18 mL/g VSS/d, and 0.104 d⁻¹ to 254.9 mL/g VSS, 25.69 mL/g VSS/d, and 0.125 d⁻¹ by the freezing + PAA pretreatment. Mechanism analysis revealed that the freezing + PAA pretreatment destroyed both extracellular polymeric substances (EPS) and microbial cells in the sludge, resulting in the increase in hydrolysis efficiency. Gene analysis showed that the hydrolytic microbes (Hyphomicrobium and norank_f_Caldilineaceae), acidogens (e.g., Petrimonas, Tissierella, and Mycobacerium) and methanogens (Methanosaeta, Methanosarcina, and Methanobacterium) were all enriched by the freezing + PAA pretreatment, with the total abundances calculated to be 10.65% and 22.07% in the control and pretreated reactors, respectively. Considering both technical and economic factors, the freezing + PAA method is feasible for sludge pretreatment. Full article

This study explores AnMBR technology as a promising method for treating wastewater from the meat-processing industry by analysing its characteristics and impact under continuous feeding. The solids were retained, utilising an ultrafiltration membrane with a pore size of 0.2 µm, and the efficacy of reducing the organic load was evaluated. Although the COD removal rate decreased from 100% at an OLR of 0.71 g/(L*d) to 73% at an OLR of 2.2 g/(L*d), maximum methane yields were achieved at the highest OLR, 292.9 Nm³/t (COD) and 397.8 Nm³/t (VS) per loaded organics and 353.1 Nm³/t (COD) and 518.7 Nm³/t (VS) per removed organics. An analysis of the microbial community was performed at the end of the experiment to assess the effects of the process and the substrate on its composition. The AnMBR system effectively converts meat-processing wastewater into biogas, maintaining high yields and reducing the loss of dissolved methane in the permeate, thanks to a temperature of 37 °C and high salt levels. AnMBR enables rapid start-up, efficient COD removal, and high biogas yields, making it suitable for treating industrial wastewater with high organic loads, enhancing biogas production, and reducing methane loss. Challenges such as high salt and phosphate levels present opportunities for a wider use in nutrient recovery and water reclamation. Full article

Anaerobic digestion (AD) can offer a promising pathway for converting animal waste into biogas. This process improves waste management practices while generating renewable energy. However, the lignocellulosic structure of animal manure, particularly in dairy and cattle manure, hinders digestion efficiency and limits biogas yield. This study investigates the application of ball milling as a pretreatment strategy to enhance the anaerobic digestion of dairy manure. By reducing particle size and disrupting lignocellulosic structures, ball milling increases the bioavailability of organic matter, thus promoting microbial conversion and boosting biogas production. Experimental results reveal that 1 h ball milling pretreatment increases biogas and biomethane production by more than 20% compared to untreated manure. Furthermore, microbial community analysis indicates that anaerobic microbes remain largely unaffected by ball milling pretreatment, unlike the changes observed with activated carbon addition. These findings suggest that ball milling is a practical, adaptable, and scalable pretreatment method to enhance the anaerobic digestion efficiency of dairy manure. It offers a sustainable solution for improved manure management and biogas production. Full article

Fossil fuels drive global warming, necessitating renewable alternatives such as biomethane (or renewable natural gas). Biomethane, primarily produced through anaerobic digestion (AD), offers a cleaner energy solution but is limited by the slow AD process. Biomass gasification followed by syngas methanation has emerged as a faster alternative. This review examines advancements in these processes over the last decade (2015–2024), focusing on techno-economic and life cycle assessment (LCA) studies. Techno-economic analyses reveal that biomethane production costs are influenced by several factors, including process complexity, feedstock type and the scale of production. Smaller gasification units tend to exhibit higher capital costs (CAPEX) per MW capacity, while feedstock choice and process efficiency play significant roles in determining overall production costs. LCA studies highlight higher impacts for gasification and methanation due to energy demands and associated emissions. However, integrating renewable hydrogen production through electrolysis, along with innovations such as sorption-enhanced gasification (SEG), can enhance overall system efficiency and reduce environmental impacts. This review critically evaluates the technical and economic challenges, along with the opportunities for optimizing biomethane production, and discusses the potential for these technologies to contribute to sustainable bioenergy solutions in the transition to a low-carbon economy. Full article

Brown seaweed could be a viable option for biogas production, with the added advantage of not competing with land-based crops, which negates the food vs. fuel argument. To optimise the process, this research investigates using mechanical and chemical pre-treatment to increase the biomethane yield of seaweed. The biomethane potential, biodegradability index, and biomethane yields were determined as well as the kinetics based on the hydrolysis of the anaerobic digestion process. Mechanical pre-treatment showed the highest increase in methane yield for the smaller size (<1.7 mm), recording yields of 126.16 mL/g VS after 28 days when compared to 31.54 mL/g VS for the control (2–3 mm). Chemical pre-treatment yielded higher methane rates (34.59–60.33 mL/g VS) than the control, but not as high as the mechanical pre-treatment processes. First-order kinetics described the anaerobic digestion process, with k-values between 0.050 and 0.106. The biodegradability index was between 0.145 and 0.580. The research increased the knowledge base of the potential of the Ecklonia Maxima seaweed to produce biogas. Careful consideration of the impact on the overall process must be completed to determine the advantages or disadvantages of including a pre-treatment step in the process under consideration. Full article

This research follows the principles of circular economy through the zero waste concept and cascade approach performed in two steps. Our paper focuses on the first step and explores the characteristics of developed biocomposite materials made from a biodegradable poly(lactic acid) polymer (PLA) reinforced with natural fibers isolated from the second generation of biomass (agricultural biomass and weeds). Two plants, Spartium junceum L. (SJL) and Sida hermaphrodita (SH), were applied. To enhance their mechanical, thermal, and antimicrobial properties, their modification was performed with environmentally friendly additives—linseed oil (LO), organo-modified montmorillonite nanoclay (MMT), milled cork (MC), and zinc oxide (ZnO). The results revealed that SH fibers exhibited 38.92% higher tensile strength than SJL fibers. Composites reinforced with SH fibers modified only with LO displayed a 27.33% increase in tensile strength compared to neat PLA. The addition of LO improved the thermal stability of both biocomposites by approximately 5–7 °C. Furthermore, the inclusion of MMT filler significantly reduced the flammability, lowering the heat release rate to 30.25%, and enabling the categorization of developed biocomposite in a group of flame retardants. In the second step, all waste streams generated during the fibers extraction process are repurposed into the production of solid biofuels (pellets, briquettes) or biogas (bio)methane. Full article

Biogas is a renewable energy source that can be locally produced from the anaerobic digestion of several organic wastes, serving as a partial substitute for natural gas derived from non-renewable sources. This work provides an overview of feedstock used for biogas production, anaerobic digestion process, biogas usage, and global and Brazilian biogas generation. In addition, the potential output in Paraná State, Brazil was evaluated. In Brazil, the full potential of biogas, especially within the agricultural sector, has not been explored. Paraná, one of Brazil’s leading agricultural producers, has emerged as a prominent biogas producer, particularly from landfill and industrial sources, primarily for electricity generation. According to the findings of this work, the biogas produced from pig, chicken, and confined cattle waste could generate 2.23 TWh of electricity, equivalent to approximately 8% of the state’s energy consumption. Moreover, the biomethane potential surpasses the 2021 production by 3.4 times. Based on the overview and results, the biogas produced in Paraná can significantly contribute to sustainable energy generation, which would reduce greenhouse gas emissions and promote a cleaner and more environmentally friendly energy matrix. Full article

An internal two-stage bioreactor constructed with a hydrogen chamber and a methane chamber with a working volume of 300 mL and 4700 mL, respectively, was operated using various kitchen waste (KW) concentrations from 10 to 80 g COD/L with a hydraulic retention time of 2 days to characterize the biomethane production performance. The results showed that daily biohythane production exhibited a similar increasing trend at KW concentrations of 10 to 40 g COD/L. The peak biomethane production was 2481 mL/day at a KW concentration of 40 g COD/L. The KW concentration could also affect the COD, carbohydrate, lipid, and protein removal efficiencies. These removal efficiencies were somehow dependent on the KW concentration, with two notable KW concentration groups of 10–20 g COD/L and 40–80 g COD/L. After 80 days of cultivation, Firmicutes dominated the hydrogen chamber, and Methanobacteriaceae and Methanomicrobiaceae dominated the methane chamber. This study presents the optimal KW concentration for high biohythane production efficiency in a novel internal two-stage bioreactor and reveals the dominant microorganisms in its microbial community. Full article

This review provides a comprehensive overview of the advancements and challenges of anaerobic digestion technology in waste stream treatment plants under the framework of the circular economy, emphasizing its role in achieving “dual carbon” goals. As climate change intensifies, with waste stream treatment contributing significantly to global emissions, there is a pressing need to optimize energy efficiency and reduce carbon outputs in this sector. Anaerobic digestion is highlighted as a solution for converting organic waste into renewable biogas and digestate, enabling energy self-sufficiency and reducing greenhouse gasses. The study highlights that anaerobic digestion enables the conversion of organic waste into renewable biogas and nutrient-rich digestate, facilitating energy self-sufficiency and significant reductions in GHG emissions. Successful implementations, such as in Weifang, China, demonstrate the feasibility of upgrading biogas into biomethane for local energy use. Advanced technologies like bioelectrochemical methanation and membrane bioreactors enhance biogas production efficiency, while co-digestion proves effective even in challenging conditions. Despite these advancements, the review identifies critical challenges, including high investment costs, technical inefficiencies, and regulatory barriers, particularly in developing countries. This study provides insights into integrating anaerobic digestion with circular economy principles and offers a foundation for future policies and research aimed at achieving carbon neutrality and sustainable waste management. Full article

The rapid growth of the world population led to an exponential growth in industrial activity all around the world. Consequently, CO₂ emissions have risen almost 400% since 1950 due to human activities. In this context, microalgae biomass has emerged as a renewable and sustainable feedstock for producing third-generation biofuels. This study explores the laboratory-scale production of bioethanol and biomethane from dried algal biomass. The first step was to evaluate and optimize the production of glucose from the biomass. Thus, three different techniques with three different solvents were tested to identify the most effective and efficient in terms of saccharification yield. With the assistance of an autoclave or a high-temperature water bath and 0.2 M NaOH as a solvent, yields of 79.16 ± 3.03% and 85.73 ± 3.23% were achieved which correspond to 9.24 and 9.80 g/L of glucose, respectively. Furthermore, the most efficient method from the pretreatment step was chosen to carry out a factorial design to produce bioethanol. The experiments showed that the loading of cellulase was of crucial importance to the optimization of the process. Optimized ethanolic fermentation yielded ethanol concentrations up to 4.40 ± 0.28 g/L (76.12 ± 4.90%) (0.3 Μ NaOH, 750 μL/g_cellulose and 65 μL/g_starch), demonstrating the critical role of cellulase loading. Biomethane potential (BMP) assays on fermentation residues showed increased yields compared to untreated feedstock, with a maximum methane yield of 217.88 ± 10.40 mL/gVS. Combined energy production from bioethanol and biomethane was calculated at up to 1044.48 kWh/tn of algae feedstock, with biomethane contributing 75.26% to the total output. These findings highlight the potential of integrated algae-based biorefineries to provide scalable and sustainable biofuel solutions, aligning with circular economy principles. Full article

Increasing energy demand and limited non-renewable energy resources have raised energy security concerns within the European Union. With the EU’s commitment to becoming the first climate-neutral continent, transitioning to renewable energy sources has become essential. While wind and solar energy are intermittent, consistent and reliable green energy sources, such as biogas and biomethane, offer promising alternatives. Biogas and biomethane production from biomass address key challenges, including grid stability (“supply on demand”), decentralized energy production, energy density, and efficient storage and transportation via existing natural gas infrastructure. This study examines technologies for converting woody biomass into biomethane and proposes a conceptual design utilizing the best available technologies. The system, situated in Slovenia’s Kočevje region—one of Europe’s richest forest habitats—was scaled based on the availability of low-quality woody biomass unsuitable for other applications. Combining biomass gasification, catalytic methanation, and biomethanation, supplemented by hydrogen from electrolysis, provides an effective method for converting wood to biomethane. Despite the system’s complexity and current technological limitations in energy efficiency, the findings highlight biomethane’s potential as a reliable energy carrier for domestic and industrial applications. Full article

The increasing global energy demand, coupled with the urgent need to reduce CO₂ emissions, has intensified the search for renewable energy sources. Biogas, produced from agro-industrial biomass, presents a viable solution. In beer production, brewery’s spent grain (BSG), the largest by-product by volume, offers potential for bioenergy recovery. This study applied a biorefinery approach to BSG, extracting protein hydrolysates (PH) through mild alkaline hydrolysis and nanostructured lignin (LN) via the Ionic Liquid Method. The objective was to assess biogas production from the residual biorefinery biomass and evaluate the co-digestion of BSG with Olive Mill Wastewater (OMWW) and Olive Pomace (OP), by-products of the olive oil industry. Biogas was produced in lab-scale batch reactors and the quantity of biogas produced was measured via the volumetric method. Conversely, the amount of biomethane obtained was evaluated by introducing, in the production chain, an alkaline trap. Biogas yields were the highest for untreated BSG (1075.6 mL), co-digested BSG with OMWW (1130.1 mL), and BSG residue after PH extraction (814.9 mL). The concentration of biomethane obtained in the various samples ranged from 54.5 vol % (OMWW + BSG) to 76.59 vol % (BSG). An energy balance analysis considering both the theoretical energy consumed by a semi-continuous anaerobic digestion bioreactor and the energy produced as bio-CH₄ revealed that BSG after PH extraction was the most energy-efficient treatment, producing a net energy gain of 5.36 kJ. For the scope, the energy consumption was calculated by considering a PEIO index equal to 33% of the energy produced during the day, showing the highest biogas production. In contrast, the co-digested BSG with OMWW yielded the lowest net energy gain of 1.96 kJ. This comprehensive analysis highlights the energy efficiency of different treatments, identifying which process should be improved. Full article

The biogas and biomethane sectors are crucial for the European Union’s energy transition. One strategy for achieving the EU’s biogas and biomethane targets while reducing the use of agricultural land for energy feedstock production is to use alternative biomass streams. Such a stream includes agricultural residues and by-products. A good example is crop residues after harvesting corn for grain, which are available in large quantities. Due to the fact that they are lignocellulosic biomasses, they require pretreatment. The purpose of this study was to determine the effect of ensiling enhancers on the methane yield of corn stover silages. Corn stover, which was harvested using the same technology, was ensiled in the first variant with an ensiling enhancer preparation based on bacteria of the Lactobacillus plantarum strain (DSM 3676 and DSM 3677) and two strains of propionic acid bacteria (DSM 9676 and DSM 9677), in the second variant with a formulation whose active ingredients were sodium benzoate, propionic acid, and sodium propionite, and in the third with a formulation based on lactic acid bacteria of the strain Lactobacillus plantarum and Lactobacillus Buchneri. The fourth variant was the control; that is, the material was ensiled naturally without the ensiling enhancer preparation. The use of the ensiling enhancer, based on lactic acid bacteria of the Lactobacillus plantarum and Lactobacillus Buchneri strains, reduced carbon dioxide emissions per 1 GJ of silage energy potential in the biogas production process. Specifically, the unique contribution of this research lies in demonstrating the role of ensiling enhancers in improving methane yield and reducing carbon dioxide emissions. Full article