The production of green hydrogen still faces large economic hurdles, with rates as high as $4-12/kg when compared to the price of commonplace hydrogen extracted from fossil fuels ($1-2/kg). This critical review addresses the technological and economic requirements for cost-competitive production of hydrogen by largescale water electrolysis. Four main electrolysis technologies are discussed classical alkaline water electrolysis (AWE), proton exchange membrane (PEM), solid oxide electrolysis cell (SOEC) and the emerging (AEM) technology (anion exchange membrane). Its analysis is also focused firstly on different types of coupling with renewable resources, i.e., photovoltaic solar installations, wind energy facilities, and the combined hybrid configuration. Results show that electric power accounts for about 60-80 % of the overall operational costs. Between the considered technologies, alkaline electrolysers require the lowest initial investment costs (5001200/kW) and demonstrated operational lifetime in excess of 80,000 h. While PEM systems do incur costs of $1000-2000/kW for startup investment, they do provide quick response to dynamics changes in the power inputs and so are especially attractive for renewable energy sources subject to erratic variations. Solid oxide devices realize up to 90 % efficiency but suffer from long term stability and operational complexity that hinders its broad acceptance. By 2030, attaining the $2/kg target for green hydrogen will require concurrent progress: electrolyzer Capital expenditure (CAPEX) would need to be halved, renewable power would need to cost less than $20/MWh, and utilization rates would need to remain above 50 %. Important research areas include the design of catalysts made from non-noble materials, increase of SOEC durability beyond 10,000 h of operation, and improvement methods for both grid-connected and stand-alone electrolysers. The work provides actionable blueprints to achieve cost-effective green hydrogen production at the multi-gigawatt scale needed for global decarbonization.

Due to population growth and rising living standards, municipal solid waste (MSW) generation is increasing, presenting significant environmental and sustainability challenges. While waste-to-energy (WtE) technologies have been widely studied as an alternative to conventional landfilling, existing literature primarily focuses on technological advancements in WtE processes or waste segregation challenges in isolation. However, a comprehensive evaluation of how segregation inefficiencies directly impact WtE performance and circular economy strategies remains largely unexplored. This review bridges this gap by analyzing technical and policy-related barriers to efficient MSW management. We provide a comparative assessment of thermochemical (incineration, pyrolysis, gasification) and biochemical (anaerobic digestion, composting) WtE technologies, identifying the optimal pathways based on waste composition and their economic feasibility. Additionally, this study explores the role of regulatory frameworks and circular economy principles in enhancing waste recovery and sustainable energy production. Our findings emphasize that improved waste segregation, advanced preprocessing, and policy-driven interventions are essential for maximizing WtE efficiency and reducing greenhouse gas emissions. By integrating technological insights, economic considerations, and policy recommendations, this review provides a comprehensive perspective that may help researchers, policymakers, and industry stakeholders in optimizing MSW treatment for a sustainable future.

The exploitation of renewable energy resources for energy production has been inevitable for the unremitting development of modern society. Bioenergy offers a significant perspective in this scenario for contributing to sustainable energy availability. Biomass, which is a renewable and carbon-neutral source of energy, can be converted from its various forms into gaseous, liquid, and solid fuels by adopting the established biomass conversion technologies. Specifically, thermochemical, biological, and chemical conversion processes are technologies engaged in converting biomass into various fuels. The selection of biomass feedstocks and the type of conversion processes are selected based on the obligatory end-products. The technical and energy process flowsheet, engineering design, and ultimately the economics of biomass conversion can be optimized by integrating multiple biomass conversion processes. Hence, a state-of-the-art review is presented to highlight the significance of hybrid biomass conversion technologies for enhancing the energy-efficient conversion of biomass materials. This review study is helpful in broadening the scope of selection for the biomass conversion technology and its potential integration with other biomass conversion technologies for commercial implementation and future research studies.

Polyhydroxyalkanoates (PHA) emerged as a promising material with similar physical properties as petroleum based plastic and it is biodegradable. Several microorganisms synthesize and accumulate this material under specific conditions. A strain of Bacillus megaterium (BM2) was used to produce PHA by using wasted rice, potato, fruit, cheese whey, molasses and frying oil. Since molasses, hydrolyzed rice media and frying oil produced higher yield compared to the other wasted materials so they were further optimized at various concentrations. The highest PHA yield obtained (57.33% and 53.92%) by cell mass with hydrolyzed wasted rice media and 2% molasses in Nutrient broth medium respectively whereas 56.89% PHA yield was obtained with wasted frying oil supplemented medium and wasted potato medium as well.

As global energy requirements rise and the need for climate change mitigation intensifies, green hydrogen has surfaced as a crucial clean fuel alternative for sustainable energy frameworks. This extensive review thoroughly investigates hydrogen production from biomass through thermochemical conversion methods, focusing on gasification and pyrolysis technologies. It covers essential conversion principles, reactor designs, operational conditions, and catalytic systems across various biomass feedstocks. An analysis of the literature indicates that gasification can yield hydrogen amounts ranging from 40 to 140 g H2/kg biomass, with optimal performance observed at temperatures between 700 and 900 °C, equivalence ratios of 0.2–0.4, and steam-to-biomass ratios of 0.5–1.5. In contrast, catalytic pyrolysis achieves hydrogen concentrations of 50–68 vol% in syngas under optimised conditions. Nickel-based catalysts exhibit superior performance in both processes; however, rapid deactivation due to carbon deposition, sintering, and sulfur poisoning presents a significant technical hurdle. Steam reforming and water-gas shift reactions are recognised as essential mechanisms for enhancing hydrogen content, while multi-stage purification techniques utilising pressure swing adsorption and membrane separation facilitate the attainment of fuel cell-grade purity (≧99.97 %). Techno-economic evaluations reveal that the levelised costs for hydrogen production from biomass systems range between $2 and $6 per kilogram of H2. The competitiveness of these systems against grey hydrogen is dependent on the implementation of carbon pricing strategies and supportive policy incentives. Life cycle assessments highlight substantial reductions in greenhouse gas emissions when compared to hydrogen derived from fossil fuels. Biomass-to-hydrogen systems can achieve carbon neutrality or even negative emissions when integrated with carbon capture and storage technologies. Ongoing technical challenges encompass issues such as catalyst deactivation, the need for tar formation mitigation, syngas purification, and the management of variability in biomass feedstock. This review outlines key research priorities, which include the development of advanced catalysts, process intensification, strategies for scaling up operations, and enhancing economic viability to promote the commercial adoption of biomass thermochemical conversion for sustainable hydrogen production.

In response to the global demand for cleaner energy, this research presents a resourceful and sustainable route for biodiesel production through the design of a novel catalyst derived from two agro-waste materials: chicken eggshells and coconut shell–pith biomass. The CaO/activated carbon (CaO/AC) composite catalysts were synthesized via calcination, carbonization, and wet impregnation, followed by thermal treatment, without the use of surfactants, binders, or toxic chemicals, ensuring an environmentally benign process. Characterization by XRD confirmed the presence of crystalline CaO phases and amorphous carbon. FTIR and SEM analyses further validated the functional group interactions and porous surface morphology, which are critical for catalytic performance. The catalyst was evaluated by transesterifying waste cooking oil (WCO) at varying methanol-to-oil ratios (8:1–10:1), catalyst loadings (6–8 wt

Date palm surface fibers (DPSFs) are abundantly available as municipal and agricultural biomass wastes from date palm trees, especially in the Middle Eastern and North African countries, especially United Arab Emirates. DPSFs are lignocellulosic in nature and therefore have immense potential to be used for bioenergy purposes. This study presents the conversion-dependent pyrolysis behavior, kinetic analysis, and bio-oil qualitative investigation. DPSFs were analyzed using thermogravimetric analysis at nonisothermal heating rates of 10-40 °C/min at a temperature range of 20-750 °C. Activation energy (E a) was calculated using model-free kinetics approach using Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), and Starink (STK) methods. E a analysis helps understand the link up of degradation behavior as a function of the conversion and fragmentation of cellulose, hemicellulose, and lignin. The pyrolysis of DPSFs was performed in a horizontal quartz tube flow reactor at a heating rate of 40 °C/min and within a temperature range of 20-400 °C. The condensed bio-oil was tested for qualitative analysis using a gas chromatography and mass spectroscopy (GC/MS) technique. E a values for the active pyrolysis region within a conversion range of 0.2-0.8 were 154.52, 152.40, and 152.37 kJ/mol for the OFW, KAS, and STK models, respectively. Using GC/MS, the qualitative assessment of bio-oil, based on normalized peak area percentages, showed that it consisted mainly of aliphatics (42.28%), aromatics (38.68%), and furans/other oxygenates (13.47%). 10.54% benzene and 10.94% toluene were the main contributors of aromatics, and 6.735 furfural was a dominant furanic compound. The result of this study provides an information on the composition of DPSF pyrolyzed bio-oil and suggests that the aromatic rich nature will lead to targeted recovery of BTX/phenolics compounds as well as for bioenergy applications.

Waste vegetable oil, chosen for its abundant availability, is utilised for fuel production via a novel catalyst using a hydrodeoxygenation (HDO) process. The catalyst is novel (based on composition), synthesized by modifying ZrO2 with Fe2O3 and Pt as an active metal, resulting in the final composition of Pt-Fe2O3-ZrO2 by incorporating the incipient impregnation technique. Comprehensive characterisation of the catalyst using XRD, SEM, BET, NH3-TPD, and XPS confirms its suitability for HDO. The resulting liquid oil, obtained through HDO of waste vegetable oil in the presence of Pt-Fe2O3-ZrO2, consists of hydrocarbon fractions within the aviation fuel and diesel range. Additionally, while waste vegetable oil initially contains even-numbered oxygenated hydrocarbons, the product oil results after HDO contains both odd- and even-numbered hydrocarbons, indicating the occurrence of decarbonylation, decarboxylation, and dehydration reactions. Elemental analysis reveals a 91.3% deoxygenation efficiency, demonstrating the high catalytic activity of the synthesised material and confirming its reusability, which enhances its commercial viability.

Bovine viral diarrhea virus (BVDV) is an important cattle virus that causes considerable losses to the farmers in the cattle industry. This paper discusses the development of multi epitope vaccine (MEV) against BVDV using immuneinformatics tools. We identified 24 cytotoxic T lymphocyte (CTL) epitopes, 5 helper T lymphocyte (HTL) epitopes and 9 B cell epitopes from viral poly-proteins. These epitopes were chosen due to their strong antigenic activity and non-malignant properties. A particular linker was used, and the adjuvant was incorporated to enhance immunogenicity of the MEV. The 655 amino acids that made up the final MEV vaccine are proven stable, hydrophilic and antigenic. The immune simulation analysis of the vaccine also showed good immune response in the host including the titre values of the antibodies, B-cell and T-cell activities. Conventional vaccines were outperformed by MEV regarding the breadth of recognized antigens because MEV is aimed at universal conserved sequences that span different BVDV genotypes, which significantly simplifies the challenge of the antigen heterogeneity. However, further in vitro confirmations are required to validate the computational results. The specific areas of concern include the safety, efficacy and functional feasibility of MEVs which should be tested both in the lab as well as animals. In this research, we present MEV as a more secure and effective approach to current vaccines against BVDV. The vaccine may be considered as a progressive tool for combating BVDV and decreasing the losses in cattle production.

Increased demand for renewable energy sources has heightened the research into biomass pyrolysis as a means of producing biochar and bio-oil. Moringa seeds form a potential feedstock due to their high energy content and Properties. This study hypothesizes that optimizing pyrolysis conditions and employing a Zeolite catalyst can enhance biochar and bio-oil yields. Response Surface Methodology (RSM) was used to investigate the influence of reaction temperature, time, and catalyst concentration on product yield. The highest yield of biochar was 44.26 % at 300 degrees C, 20 min, and 14 % catalyst with a calorific value of 21.00 MJ/kg, while the highest yield of bio-oil was 34.67 % at 450 degrees C, 60 min, and 6 % catalyst loading. Statistical modeling with ANOVA validated the applicability of the model, substantiating the substantial influence of reaction temperature and catalyst concentration on the product trade-off. According to the study, enhancing pyrolysis conditions improves significantly the efficiency of biomass conversion, and it further the use of biochar for carbon sequestration and soil amendment and raises bio-oil's potential for renewable energy.

With the growing global energy crisis, increasing demand for sustainable fuels, and the need for high-efficiency biodiesel production, a detailed review of emerging technologies is crucial. Unlike recent reviews, this work uniquely integrates advancements in machine learning, artificial intelligence-driven optimization, and novel biodiesel production technologies to offer a more comprehensive perspective on overcoming contemporary challenges in the biodiesel industry. Artificial intelligence and machine learning facilitate optimal biodiesel yield, enhance prediction accuracy, reduce costs, and improve process efficiency using advanced algorithms like adaptive neuro-fuzzy inference system—genetic algorithm and extreme gradient boosting. The novel technology such as controlled crushing device enables simultaneous oilseed crushing and transesterification, achieving high biodiesel yields up to 97.5

Green hydrogen has been proposed as a clean and sustainable source of energy with unrivaled potential to play a pivotal role in every country's transition toward a low-carbon economy while striving to achieve Sustainable Development Goals. Herein, we provide perspective of using green hydrogen to enhance the sustainability in Pakistan. As renewable energy resources (e.g. solar and wind power) are abundantly available in Pakistan, the production of green hydrogen linked to renewable energy resources is conscious. As a representative case, the green hydrogen project in Sindh, Pakistan was announced—hydrogen is produced by water electrolysis powered by renewable electricity generated from solar or wind power. The potential of a circular economic approach to green hydrogen production in Pakistan is discussed in terms of policy development, public and private participation, public demand, and public awareness. Green hydrogen is indeed the green light of the future for Pakistan, as it can potentially help boost its economy while mitigating climate change. The insights given by this study can be useful to further develop any future green hydrogen roadmap for Pakistan.

Biomass‐derived activated carbon (AC) offers a sustainable solution for energy and environmental applications. Compared to coal‐based AC, biomass‐derived AC reduces environmental impact while maintaining high porosity and adsorption capacity. Its synthesis involves carbonization and activation, enhancing porosity and adsorption properties. Efficiency depends on particle size, surface area, pore structure, and functional groups. Smaller particles and higher surface areas enhance adsorption, whereas micropores serve as primary adsorption sites. Functional groups influence chemical interactions. Regeneration methods extend usability. AC‐based catalysts improve hydrogen production and biodiesel synthesis. In wastewater treatment, iron oxide–impregnated AC enhances dye removal, whereas titania/AC composites boost photocatalytic degradation of organic pollutants. AC also plays a crucial role in carbon dioxide (CO 2 ) capture, with potassium hydroxide (KOH)‐synthesized AC optimizing micropore formation. AC faces challenges in biomass supply, logistics, regeneration efficiency, and adsorption selectivity, requiring innovative activation methods and surface modifications.

Background: For decades, waste governance has been a looming threat to humankind and the ecology. Waste management has consistently been a matter of dispute, impeding progress and hindering the establishment of a sustainable economy, irrespective of whether it pertains to developed or underdeveloped nations. Solid waste is a major contributor to diverse types of environmental pollution. The widespread social and economic implications of environmental pollution have had detrimental effects on the planet. Transitioning waste, a major source of pollution, can not only alleviate ecological concerns but also drive economic prosperity through sustainable energy production by harnessing it as fuel. Methods: Municipal solid waste (MSW) is a promising resource for generating biofuels through various waste-toenergy conversion pathways, offering economic viability and reliability. Numerous strategies have been introduced with many modifications in various countries leading to extensive biofuel production. Significant findings: A comprehensive assessment was conducted to thoroughly examine the contemporary status of municipal solid waste management, focusing on the efficient disposal and diversion of waste and analyzing the associated opportunities and challenges worldwide. Waste-to-energy technologies have been systematically discussed, providing a comprehensive overview of the biofuels produced with policies and challenges in different countries.

This study presents an innovative and sustainable approach to biodiesel production by introducing Bismarckia nobilis leaf—an underutilized biomass—as a novel precursor for synthesizing a green carbon heterogeneous catalyst. The catalyst was developed through an optimized process involving controlled carbonization and acid treatment, and its application in a custom-designed bubble reactor significantly enhanced mass transfer and mixing efficiency compared to conventional batch systems. Green carbon was synthesized from waste Bismarckia nobilis leaf pretreated with hydrochloric acid and carbonized at several temperatures (250 °C, 350 °C, and 450 °C) and periods (60–120 min), followed by washing with different acids (hydrochloric acid, citric acid, and acetic acid). Characterization employing Fourier transform infrared spectroscopy for functional group analysis, Brunauer–Emmett–Teller for surface area measurement, and scanning electron microscopy for morphological evaluation revealed that the sample treated at 350 °C for 90 min and washed with hydrochloric acid exhibited the maximum surface area and well-developed mesoporosity, making it optimal for catalytic applications. This optimized waste Bismarckia nobilis leaf-derived green carbon served as a heterogeneous catalyst in the transesterification step of a dual-stage biodiesel production process, following acid-catalyzed esterification for free fatty acids reduction. The process achieved 92.86

Among the various strategies for ammonia production, the electrocatalytic reduction of nitrogen is promising method and various heterogeneous electrocatalysts are being developed to facilitate the nitrogen reduction reaction (NRR) for ammonia synthesis. However, these methods are not suitable for large-scale commercialization due to the high stability and nonpolar nature of the N2 bond, which is further challenged by competing hydrogen evolution reactions. Elevated temperatures enhance the Faradaic efficiency (FE) but also increase the reverse reaction rate, leading to the dissociation of ammonia. Thus, nitrate has been used as an alternative reagent for electrocatalytic ammonia synthesis because it shows higher solubility and more feasible bond dissociation. Electrocatalytic nitrate reduction achieves high FE and NH3 yields, surpassing those of the competitive hydrogen evolution reactions experienced in the NRR. Various electrocatalysts have been used for effective nitrate reduction, including metal oxide-based, metal alloys, non-oxide, metal phosphides, metal sulfides, metal carbides, and carbon-based electrocatalysts. Previously, researchers addressed these methods’ advantages but lacked a comparative assessment. This review addresses this gap, thoroughly examines the mechanisms involved in the electrocatalytic synthesis of NH3, including various nitrate and NRR pathways, and proposes a reliable protocol for detecting ammonia. This work provides important insights on recent advancements in innovative electrocatalysts.

This study explores the use of a novel heterogeneous CoZnFe4O8 nanocatalyst for biodiesel production from a sustainable and innovative blend of waste cooking oil and neem oil feedstock. Utilizing waste cooking oil and inedible neem oil feedstock to produce biodiesel provides a green and economical way to produce renewable and environmentally friendly fuel while simultaneously reducing waste and valorizing inedible oils. Additionally, this feedstock blend does not threaten food or land resources as opposed to feedstocks obtained from edible resources. To fulfill the rising demand for biodiesel and address issues related to lower ester yields, particularly when utilizing waste cooking oils with high free fatty acid concentration, there is an urgent need for more effective processes, including two-stage transesterification. The novel CoZnFe4O8 nanocatalyst employed in this study demonstrated high efficiency in biodiesel production thanks to its high surface area, mesoporous structure, and catalytic properties. The effect of key process parameters, including catalyst concentration, reaction time, alcohol-to-oil molar ratio, and oil blend ratio, was investigated to evaluate the performance of the nanocatalyst and optimize the biodiesel yield with the help of Response Surface Methodology (RSM). The optimized process achieved a yield of 94.23% under optimum parameters of 2.13 wt% catalyst, 6.80:1 methanol-to-oil ratio, 4 h, and a ratio of waste cooking oil to neem oil of 98.32:1.68. The predicted and experimental values were in close agreement, indicating that the model was adequate. Additionally, detailed catalyst characterization, including analysis of the surface area, structure, and thermal stability, was carried out. Similarly, the biodiesel was characterized to assess its quality through heating value, density, Fourier Transform Infrared (FTIR) spectroscopy, and ultimate analysis. The recovery and reusability of the nanocatalyst were also investigated, highlighting its potential for multiple reaction cycles. The novel CoZnFe4O8 nanocatalyst and innovative feedstock blend demonstrated high efficiency in biodiesel production comparable to other nanocatalysts and feedstocks reported in the literature, highlighting their potential as an efficient and sustainable method to produce biofuels.

This paper provides a comprehensive review of hybrid waste-to-energy (WTE) systems that integrate anaerobic digestion (AD) and biomass gasification, emphasizing their synergistic benefits in sustainable energy production and waste management. By combining biochemical and thermochemical processes, these hybrid systems maximize energy recovery, optimize resource utilization, and significantly mitigate environmental impacts. The study highlights the principles and operational dynamics of standalone AD and gasification technologies, showcasing how their integration addresses limitations such as incomplete biomass conversion and excessive digestate production. Hybrid systems demonstrate superior performance in converting diverse biomass feedstocks, including municipal solid waste (MSW), agricultural residues, and food waste, into renewable energy and valuable by-products. Advancements in reactor designs, pretreatment techniques, and system configurations are discussed, with a focus on enhancing energy efficiency and reducing greenhouse gas (GHG) emissions. Pretreatment methods such as AD pretreatment and advanced sorting mechanisms are explored to address feedstock variability and improve process stability. Key synergies, such as utilizing waste heat from gasification to dry AD residues, further boost overall system efficiency. The paper identifies critical operational parameters such as feedstock composition and reactor conditions that influence system performance and explores emerging solutions. Economic and environmental benefits, such as improved energy yields and cost efficiency, demonstrate the potential of hybrid AD–gasification systems. Despite the advantages, challenges persist, particularly in scaling hybrid systems and managing feedstock variability. Infrastructural limitations and the complexity of balancing AD and gasification processes remain significant barriers to widespread adoption. By reviewing existing research and case studies, this paper underscores the critical role of hybrid systems in achieving global renewable energy goals and sustainable waste management practices. Ultimately, hybrid AD–gasification systems offer a promising pathway for transitioning to cleaner energy systems, maximizing waste valorization, and supporting the global shift toward a circular economy.

The current study demonstrates a safe and effective approach for generating gasoline biofuels RON 98 and RON 92 using light straight-run naphtha, isomerate, and reformate as base components. These biofuels are based on isopropyl alcohol, which has strong anti-detonation qualities. The impact of isopropanol as a clean, renewable, sustainable, and environmentally beneficial additive on the gasoline pool was demonstrated by analyzing the physical and chemical characteristics of the generated blends. Commercial gasoline with a rating of 92 octane and gasoline biofuel with ratings of 98 and 92 octane were compared using the exhaust emissions properties, which include carbon monoxide (CO), unburned hydrocarbons (HC), carbon dioxide (CO2), nitrogen oxides (NOX), and oxygen (O2). Engine speeds at which the analysis emissions were conducted were 1000, 1950, and 2650 rpm, respectively. The results of the experiment demonstrated an improvement in both the quantity and light naphtha grade. The findings reported that gasoline biofuels, particularly the 98 RON blend, reduced HC and CO emissions compared to commercial gasoline, with more significant improvements at higher engine speeds. Moreover, gasoline biofuel RON 98 showed superior fuel efficiency with the lowest specific fuel consumption and CO₂ emissions across all engine speeds. The produced gasoline biofuel 98 RON demonstrated the lowest CO emissions, with a marked drop from 1.99 % at 1000 rpm to 0.65 % at 2650 rpm. Lastly, 98 RON gasoline biofuel exhibited the highest air velocity at higher engine speeds, indicating potential improvements in engine performance under those conditions. These results suggest that gasoline biofuel RON 98 could be a cleaner and more efficient alternative to traditional gasoline, particularly in high-performance engine applications.