Anaerobic digestion (AD) is a widely implemented biotechnological process for treating organic wastes, such as food waste, providing the dual advantages of renewable energy production and nutrient recovery. Nonetheless, the heterogeneous composition of food wastes—characterized by high moisture content, lipids, salts, and nitrogenous compounds—often results in process instability and suboptimal biomethane yields. The use of multifunctional additives offers a promising avenue to enhance buffering capacity, microbial activity, and overall system stability. This investigation examined the effects of a compost-based additive (CBA) containing 25 functional compound agents (FCAs), including bacteria and fungi involved in organic matter decomposition, enzymatic activity, nitrogen fixation, methane production, and sulfate and ammonia reduction, on the AD of food waste. Batch AD experiments were performed under mesophilic conditions (37 ± 1°C) over a 20-day digestion period. The influence of CBA supplementation on biomethane production and key stability parameters, including pH, alkalinity, total volatile fatty acids (TVFAs), FOS/TAC ratio, and electrical conductivity (EC), was systematically evaluated. Results showed that CBA supplementation significantly improved process stability by increasing alkalinity and overall buffering capacity, which facilitated more effective TVFA degradation. The CBA-amended reactor achieved a TVFA degradation efficiency of 78.55%, nearly double that of the control (36.10%) (p < 0.01). Although pH is directly influenced by TVFA concentration, no statistically significant differences in pH were observed between treatments (p > 0.05), indicating that the enhanced alkalinity effectively maintained stable conditions. Furthermore, the EC in the CBA-treated reactor decreased by 19.7% relative to its initial value, while the FOS/TAC ratio declined to 0.10 by the end of the digestion period, indicating enhanced metabolic balance and a markedly reduced risk of acidification. These stability enhancements translated into improved performance, with the CBA-treated reactor attaining a maximum cumulative biomethane yield of 291.80 ± 6.09 mL g⁻¹ VS, representing a 10.51% increase over food waste digestion without additives. In conclusion, this study demonstrates that CBA can enhance process stability and biomethane production from food waste, highlighting its potential to support sustainable, low-carbon energy generation through the AD process.

I. Introduction
Global energy security positions solar energy as a strategic alternative, although the efficiency of photovoltaic systems is constrained by the non-linear nature of I-V curves under environmental variations. MPPT techniques are essential for optimizing this operation. However, conventional methods, such as P&O, fail under transient regimes. This work proposes the ANFIS model as a robust solution, integrating Artificial Neural Networks and Fuzzy Logic to provide dynamic adaptation without the need for complex mathematical modeling.

II. Methodology
An experimental database of 17,193 real-world irradiance samples, collected from a university plant, was utilized. The system was sized using Yingli polycrystalline modules (245 W, 15.1% efficiency) and simulated within the MATLAB/Simulink environment. The model was trained with 80% of the data and validated with the remaining 20%, exploring four scenarios that varied the number of membership functions (5 and 8) and training epochs (100 and 150). The ideal configuration was defined by the lowest prediction error and the highest coefficient of determination (?²).

III. Results
Simulations confirmed the high tracking capability of the ANFIS controller. It was observed that increasing the training to 150 epochs significantly optimized the stability of the estimated power. Despite initial oscillations typical of the transient regime, the voltage (?_??) and current (?_??) curves converged rapidly. Scenario B_2 (8 functions, 150 epochs) exhibited superior performance, achieving an ?² of 0.91 and the lowest Mean Squared Error (MSE) of 0.6895.

IV. Conclusions
The ANFIS model proved highly effective in extracting the maximum power point under real-world disturbances. The integration of climatic and electrical variables resulted in rapid responses and low oscillation around the MPP, validating the technique as a robust tool for the optimization of photovoltaic systems.

The increasing global demand for sustainable fuels has greatly boosted research into converting waste cooking oil (WCO) into biodiesel, positioning it as a renewable alternative to conventional fossil diesel. This study thoroughly investigates the transesterification of WCO using a calcium oxide (CaO) heterogeneous catalyst. The research includes kinetic modelling, process simulation, and an extensive environmental assessment to provide a comprehensive understanding of the process. The process conditions set for this study included a temperature range of 30°C to 70°C, with methanol-to-oil molar ratios varying from 6:1 to 14:1. Reaction times ranged from 60 to 100 minutes, and a catalyst loading of 3 wt.% CaO was used. To characterise the reaction kinetics effectively, a pseudo-first-order kinetic model was utilised. In this investigation, the activation energy (Ea) was determined to be 37.16 kJ·mol⁻¹, indicating an energetically favourable reaction pathway under the moderate operating conditions used. The validation of the kinetic model was conducted using ChemCAD simulation, which accurately predicted a maximum conversion rate of 98.96% at a methanol-to-oil molar ratio of 6:1 at 70°C. This confirms the strong catalytic efficiency and practical reusability of CaO in the transesterification process. Additionally, a cradle-to-gate Life Cycle Assessment (LCA), focusing on Global Warming Potential (GWP), showed that producing one tonne of biodiesel results in emissions of only 640 kg CO₂-equivalent. This figure is approximately 80% lower than the typical emissions of 3200–3500 kg CO₂-equivalent associated with petroleum diesel production. The analysis revealed that methanol synthesis and process energy consumption were the primary contributors to overall emissions, while the environmental impacts associated with catalyst usage and WCO collection remained minimal. In conclusion, the findings of this study demonstrate that transesterification of WCO catalysed by CaO is not only technically feasible but also environmentally advantageous, offering a promising pathway towards sustainable low-carbon fuel production and effective waste valorisation. This research aligns with the United Nations Sustainable Development Goal 12 (Responsible Consumption and Production), as it promotes sustainable practices and reduces waste by converting WCO into biodiesel.

The development of highly efficient and economically viable solar-driven catalysts for hydrogen (H₂) production is of paramount importance in the pursuit of sustainable and clean energy alternatives to fossil fuels. Among the materials explored for this purpose, transition metal dichalcogenides (TMDs) and two-dimensional (2D) materials have gained significant attention due to their unique structural, electronic, and surface properties, which make them promising candidates for photocatalytic applications. In particular, MXenes such as Ti₃C₂ stand out for their metallic conductivity, high surface area, hydrophilicity, and versatile functionalization possibilities. In this study, a series of MoS₂/Ti₃C₂ (X) heterostructured nanocomposites (where X = 1, 3, 5, 7, and 9 wt.%) were successfully synthesized via a simple one-step hydrothermal method. The synthesized materials were thoroughly characterized using state-of-the-art analytical and spectroscopic techniques to investigate their composition, morphology, crystallinity, and optical features. Photocatalytic hydrogen evolution tests were performed in a methanol–water sacrificial solution under visible-light irradiation to evaluate their activity. Among all samples, the MoS₂/Ti₃C₂ 5% composite demonstrated the highest hydrogen evolution rate, outperforming pure Ti₃C₂, pure MoS₂, and the other composites in the series. The superior photocatalytic performance of the MoS₂/Ti₃C₂ 5% heterojunction is attributed to the synergistic interaction between the MoS₂ nanosheets and Ti₃C₂ MXene layers, which facilitates more efficient interfacial charge transfer. The formation of a well-matched heterojunction promotes rapid electron migration while suppressing recombination of photogenerated electron–hole pairs, resulting in enhanced photocatalytic activity. Electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) analyses further support this conclusion by revealing improved charge separation efficiency and lower recombination rates in the optimized composite. Overall, this work provides compelling evidence that 2D MoS₂/Ti₃C₂ hybrid structures serve as high-performance, durable, and cost-effective photocatalysts for solar-driven hydrogen production. The results not only highlight the potential of MXene-based heterostructures in renewable energy applications but also offer valuable design insights for developing next-generation hybrid photocatalysts for efficient solar energy conversion.

Introduction

The decarbonization of the aviation sector requires the deployment of renewable energy pathways capable of minimizing greenhouse-gas emissions while maintaining fuel quality and energy density. Sustainable Aviation Fuel (SAF) derived from biomass gasification and Fischer–Tropsch (FT) synthesis represents a viable route to achieve net-zero aviation. In Spain, the large availability of agricultural and forestry residues allows for decentralized production schemes located close to biomass sources.

Santamarta et al. (2025, Resources) proposed a conceptual decentralized SAF model based on residual biomass gasification but did not include detailed process validation. This study extends that framework by developing a rigorous Aspen Plus® simulation of the gasification stage and performing a techno-economic analysis to quantify the performance, syngas composition, and investment cost of a 5 MWth modular plant integrated into the decentralized SAF system.

Methods

The modeled process represents a downdraft gasifier using mixed vine-pruning and forestry residues with steam and oxygen as gasifying agents.
The process flow consists of five main Aspen Plus® blocks:

• RYIELD—biomass decomposition into elemental constituents (C, H, O, N, S, H₂O, ash)
• RGIBBS—global equilibrium for oxidation and reduction reactions
• RCSTR—reforming and Water–Gas Shift (WGS) reactor for H₂/CO adjustment
• COOLER—controlled heat recovery and gas cooling to 350 °C
• SEP—removal of solids and condensates.

To avoid full thermodynamic equilibration of the WGS reaction, the RCSTR was operated with a limited conversion, representing its kinetic limitation in real downdraft gasifiers and yielding a more realistic H₂/CO ratio close to 2.

Thermodynamic properties were calculated using the Redlich–Kwong–Soave (RKS) equation of state. Complete equilibrium was assumed in the main gasification zone, with total heat losses below 5%. Sensitivity analyses of temperature (850–1000 °C), equivalence ratio (ER = 0.25–0.35), and steam-to-biomass ratio (S/B = 1.0–2.5) were performed to optimize gas yield and composition. The target H₂/CO ratio (1.8–2.2) was selected for compatibility with FT synthesis.

Results

The optimum operating point was found at 950 °C, ER = 0.30, and S/B = 2.0, producing a clean syngas with 24.6 % H₂, 35.4 % CO, 33.7 % CO₂, and 4.9 % CH₄, resulting in an H₂/CO ratio of 1.98, cold-gas efficiency (CGE) of 49.3 %, and carbon conversion of 85 %.
The lower heating value (LHV) reached 11 MJ·Nm⁻³, consistent with high-performance O₂ + H₂O gasification systems. Limiting the WGS extent reduced CO₂ formation (≈ 29 %) and improved agreement with pilot-scale data.

The techno-economic analysis, based on cost correlations integrated in Aspen Plus®, yielded a total CAPEX of 12 million euros for the 5 MWth modular unit. The gasifier accounted for 3.5 M EUR (≈ 29 %) of the investment, followed by gas cleaning (21 %) and auxiliary systems (18 %). These results validate the assumptions used by Santamarta et al. (2025) and demonstrate the technical and economic feasibility of modular SAF production plants in Spain.

Conclusions

The Aspen Plus® model provides both technical and economic validation of the decentralized SAF concept. The combination of steam–oxygen gasification and partial WGS conversion delivers a syngas suitable for direct Fischer–Tropsch synthesis (H₂/CO ≈ 2, LHV ≈ 11 MJ·Nm⁻³) with realistic process behavior.

The derived CAPEX of 12 M EUR per 5 MWth unit supports the economic viability of a distributed network of small gasifiers capable of valorizing local biomass while minimizing transport and emissions. This integrated simulation–economic framework bridges the gap between conceptual design and industrial deployment, strengthening the basis for SAF production within the European renewable-energy transition.

Nickel (Ni) exsolution from perovskite oxide lattices has emerged as a highly effective strategy to develop active, stable, and coking-resistant anodes for protonic ceramic fuel cells (PCFCs). Conventional Ni-based anodes, although widely employed due to their excellent catalytic activity toward the hydrogen oxidation reaction (HOR), suffer from several critical challenges under typical operating conditions. These include severe degradation caused by Ni particle agglomeration, delamination from the ceramic backbone, and carbon deposition when exposed to hydrocarbon fuels. Such structural and chemical instabilities significantly limit the long-term durability and performance of PCFCs. To address these limitations, the present study explores the in situ exsolution of Ni nanoparticles from doped perovskite oxide anodes as a means to achieve strong metal–support interaction and enhanced catalytic robustness. During controlled reduction, Ni cations migrate from the perovskite lattice to the surface, nucleating as uniformly distributed nanoscale particles that are partially embedded, or “socketed,” into the oxide framework. This anchored configuration ensures excellent thermal and mechanical stability, preventing particle coarsening and detachment even under prolonged operation. The resulting exsolved Ni–oxide interface provides abundant active sites for electrochemical reactions and facilitates rapid charge and proton transfer at the electrode–electrolyte boundary. In this work, the exsolution behavior of Ni from doped perovskite anodes was systematically investigated under various reduction temperatures and atmospheres to tune nanoparticle size, distribution, and density. Comprehensive structural and microstructural characterizations using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), and X-ray photoelectron spectroscopy (XPS) confirmed the formation of finely dispersed, metallic Ni nanoparticles anchored firmly to the perovskite surface. Electrochemical analyses, including current–voltage (I–V) characteristics and electrochemical impedance spectroscopy (EIS), demonstrated that the Ni-exsolved anodes exhibited substantially lower polarization resistance and higher peak power density than their conventional Ni-impregnated counterparts. The enhanced electrochemical performance is attributed to the synergistic effect between the exsolved Ni nanoparticles and the perovskite lattice, which collectively promote efficient HOR kinetics, proton conduction, and electronic transport. Moreover, redox cycling experiments revealed remarkable reversibility of the exsolution process, with Ni nanoparticles re-dissolving and re-exsolving without loss of performance or structural integrity. This self-regenerative capability contributes to long-term operational stability and resistance to fuel impurities, such as carbonaceous species, thereby mitigating coking and degradation. Overall, this study highlights Ni exsolution as a transformative approach for the rational design of advanced PCFC anodes that combine high catalytic activity, structural resilience, and long-term stability. The findings provide fundamental insights into the relationship between exsolution chemistry, microstructural evolution, and electrochemical functionality. By leveraging the unique properties of exsolved metal–oxide interfaces, this work contributes to the development of next-generation, high-efficiency, and sustainable PCFC systems for clean energy conversion and storage applications.

Rising carbon emissions and energy insecurity have become part of the major issues affecting the development of African economies. Renewable capacity additions, that is, renewable energy generation, through renewable energy sources, such as hydropower, solar power, wind power, and geothermal power, play a vital role in ensuring energy efficiency and are clean and environmentally friendly. The increasing deployment of renewable energy in African countries raises some serious questions about its role in strengthening energy security and reducing carbon emissions, even though they are widely recognised as pathways to resilience. However, there is a paucity of empirical evidence with robust causal implications to ascertain this claim in the case of Africa. This study is therefore aimed at investigating the impacts of renewable capacity additions—solar, wind, hydro, and geothermal—on improving energy security and reducing emissions in Africa. The study will make use of the panel ARDL estimation technique to analyse data across 12 African countries from 2000 to 2024. In order to ascertain the validity of the results obtained, the study will also employ the use of the fixed-effects estimation technique to serve as a robustness check. Energy security will be proxied by indicators like fossil fuel import dependence, electricity access rates, and frequency of supply disruptions. Carbon intensity and emissions will be used to capture environmental outcomes. The expected outcome of this study is such that renewable capacity additions will propel energy security in Africa both in the short and long run. Policy-wise, the findings from this study are expected to strengthen the argument that renewable energy is also a resilience-enhancing tool for African economies. By investigating the direct impacts of renewable capacity additions in improving energy security and reducing emissions in Africa, this study is crucial and holds potential for high-impact policy recommendations, actionable insights, and scholarly contributions that are crucial for the region’s renewable energy generation trajectory.

Introduction: Transitioning to green energy for a greener environment requires moving away from fossil fuels. Agrivoltaics seems like a promising solution for a sustainable transition, aligning with current energy and environmental trends to reduce carbon emissions. Agrivoltaics has gained significant momentum in recent years. Agrivoltaics is the concept of dual use of the same land: solar panels generate solar energy on the agricultural land, and crops are cultivated beneath them. This generates two sources of income for the farmers. This concept is being widely welcomed across the world. It is a novel approach to addressing the severe challenges posed by climate change.

Methods: This study aimed to obtain solutions to enhance agrivoltaics resilience through a satellite monitoring system. With current technological advancements, we have a range of tools and platforms to detect issues in the agrivoltaics system, including crop health, soil fertility, and atmospheric conditions. All these can be identified at the early stages and trying to resolve these issues through various measures may help to increase yield. Through traceability solutions, it helps determine the flow of energy and farm products across the supply chains. In addition, fleet management system tools help optimize the performance of agricultural and energy equipment. Above all, carbon impacts and carbon footprinting can be monitored more frequently to reduce the levels of carbon before it enters the atmosphere. With these support systems in place, installing solar panels on agricultural land could drive a more sustainable transition in the energy industry. Agrivoltaics can be considered a tool for resilience in climate transition, thereby advancing a sustainable transition.

Results: Power and energy yield help determine the efficiency of agricultural field output. This depends on the placement of different panels in the agricultural field. Crop yields are also significantly determined by the transparency of the lighting rays through panels placed in the field. Additionally, agrivoltaics strongly supports rural electrification in developing nations, where agriculture is the main source of income. With proper government support and subsidies, the agricultural sector could be covered with solar panels. There is another major benefit to the agricultural sector: water conservation through refined irrigation practices, achieved by installing solar panels above the crops. This significantly helps in water conservation. Pesticide use can be reduced by adopting agrivoltaics in the field, thereby improving crop quality. This parallel even helps in reducing groundwater contamination. Hence, Agrivoltaics can drive ecological and sustainable power transitions without compromising agricultural productivity and solar energy generation.

Conclusion: Agrivoltaics appears to be a promising solution for addressing the challenges we face in the food, water, and energy sectors. But the success rate also depends on the regional supportiveness for solar radiation availability and crop suitability. The concept of agrivoltaics enhances land-use efficiency and modifies the microclimate by reducing soil and air temperatures in the surrounding area. The major benefits of generating solar energy in reducing greenhouse gas emissions are achieved in parallel with crop cultivation. Hence, supporting the sustainable energy transition.

This study presents an extensive compositional characterization of biodiesel produced from sweet almond (Prunus amygdalus “dulcis”) seed oil, complementing earlier analyses of its physicochemical and fuel performance properties. While previous investigations evaluated parameters such as viscosity, density, flash point, acid value, and cold-flow behavior, the present work focuses on the detailed molecular composition of both the feedstock and its resulting biodiesel, with particular emphasis on the fatty acid (FA) and fatty acid methyl ester (FAME) profiles. Comprehensive knowledge of these molecular constituents is critical for predicting biodiesel stability, combustion efficiency, and compliance with established international standards. The biodiesel was synthesized via base-catalyzed transesterification using a heterogeneous calcium oxide (CaO) catalyst derived from locally available materials. Gas Chromatography–Mass Spectrometry (GC/MS) was used to identify and quantify the dominant fatty acids in the crude almond oil and the corresponding methyl esters formed after conversion. GC/MS analysis of the raw oil revealed a rich fatty acid composition dominated by oleic acid (20.78%), n-hexadecanoic acid (10.65%), and octadecadienoic acid (8.47%). The distribution reflects an oil rich in both monounsaturated and polyunsaturated fatty acids, a desirable characteristic for biodiesel production due to its potential to enhance key fuel properties. Following transesterification, these fatty acids were transformed into their respective methyl esters, with oleic acid methyl ester (20.91%) and octadecadienoic acid methyl ester (18.32%) identified as the most abundant FAMEs. The predominance of these unsaturated esters strongly correlates with the biodiesel’s previously reported superior cold-flow characteristics, including a pour point of -9 °C and a cloud point of -3 °C. High monounsaturated ester content improves fluidity and contributes to oxidative stability, while polyunsaturated esters enhance low-temperature operability. This correlation underscores the significance of molecular-level profiling in assessing and predicting biodiesel performance. Overall, the findings confirm that the fatty acid composition of almond seed oil plays a crucial role in determining the quality of the resulting biodiesel and its ability to meet ASTM D6751 and EN 14214 specifications. The results validate sweet almond seed oil as a viable, sustainable, and technically promising non-conventional feedstock for biodiesel production in Nigeria. Its adoption could support cleaner energy alternatives, improve energy security, and contribute meaningfully to addressing the food–fuel dilemma.

The increasing global demand for clean energy carriers, coupled with the urgent need to mitigate greenhouse gas emissions and manage municipal solid waste (MSW) sustainably, has intensified interest in integrated waste-to-energy and carbon capture technologies. Hydrogen-rich syngas is widely recognized as a versatile intermediate for power generation, synthetic fuels, and chemical production, while carbon capture and utilization (CCU) offers a pathway to transform CO₂ from a liability into value-added products. Gasification of MSW provides an attractive solution by simultaneously addressing waste disposal challenges and enabling renewable hydrogen production. However, conventional gasification processes are often constrained by CO₂ emissions, energy inefficiencies, and limited economic competitiveness. This study presents an integrated modelling and simulation of waste gasification, calcium looping, and carbon capture utilization (CCU) for sustainable hydrogen-rich syngas and value-added calcium carbonate production. A gasification system processing 1000 kg/h of municipal solid waste was simulated in Aspen Plus, producing syngas with 54–58 vol% H₂, 23–26 vol% CO, 10–12 vol% CO₂, and 6-7 vol% CH₄, corresponding to a hydrogen output of approximately 520 kg/h and a cold gas efficiency of 78%. In parallel, 500 kg/h of waste cow bone was calcined to generate 320 kg/h CaO with >95% conversion, achieving 88% CO₂ capture efficiency and yielding 560 kg/h of CaCO₃ via carbonation. Exergy analysis revealed an overall exergy efficiency of 62%, with the gasifier accounting for the largest irreversibility share (35%). Thermo-economic assessment showed a total capital investment of USD 6.8 million, an annual net profit of USD 1.2 million, a net present value (NPV) of USD 4.5 million, and a payback period of 4.1 years. Sensitivity analysis identified gasification temperature and CaO regeneration efficiency as dominant factors affecting hydrogen yield and system profitability. The strong coupling between gasification operating conditions and calcium looping performance highlights the importance of integrated process design rather than isolated unit optimization. Overall, the proposed framework demonstrates a scalable and environmentally robust pathway for carbon-efficient hydrogen production, simultaneous waste valorization, and circular carbon utilization through CaCO₃ synthesis. By converting municipal solid waste and animal-derived residues into clean energy and marketable materials, the system aligns with circular economy principles and offers practical support for the transition toward low-carbon, resource-efficient, and sustainable energy systems.