Anaerobic digestion represents a relevant biological technology for the energy recovery of biodegradable waste and for reducing environmental impact, contributing to the transition toward sustainable and circular energy systems. The efficiency of this process is closely correlated with the structure, composition, and diversity of microbial communities involved in the sequential stages of hydrolysis, acidogenesis, acetogenesis, and methanogenesis. Each microbial group plays a specific and essential role: hydrolytic bacteria break down complex polymers into simpler molecules, acidogenic bacteria convert these molecules into volatile fatty acids, acetogenic bacteria produce acetate, hydrogen, and carbon dioxide, and methanogenic archaea finalize the process by generating methane-rich biogas. The present paper examines the relationship between microbial diversity and the energy efficiency of anaerobic digestion, considering and synthesizing data, trends, and conclusions reported in the scientific literature. The main microbial groups involved in the process are analyzed, including hydrolytic and acetogenic bacteria as well as methanogenic archaea, highlighting the biological mechanisms and interactions that influence process stability, energy yield, and system resilience under variable operational conditions. In addition, trends identified in recent studies regarding the impact of microbial diversity on biomass-to-energy conversion and on the reduction of greenhouse gas emissions associated with biodegradable waste management are discussed, emphasizing the importance of microbial community composition for sustainable energy production. The analysis indicates that higher microbial diversity is associated with increased energy efficiency, more stable biogas production, reduced accumulation of intermediate metabolites, and enhanced resilience of the anaerobic digestion process in response to fluctuations in feedstock composition or environmental conditions. In this context, integrating microbial and biological considerations into the design, monitoring, and operation of anaerobic digestion facilities can significantly contribute to optimizing energy performance, improving process reliability, and promoting environmentally sustainable solutions for the management of organic waste. This perspective underscores the central role of microbiology in advancing renewable energy technologies and supporting the broader goals of sustainable development and environmental protection.

Photovoltaic greenhouses have emerged as a promising solution to enhance the energy sustainability of protected agriculture by simultaneously enabling crop production and on-site renewable energy generation. This approach is particularly relevant in high-altitude tropical regions, such as the Bogotá Savanna, where solar availability is relatively stable throughout the year and energy costs represent a significant operational constraint. However, the integration of photovoltaic systems introduces shading effects that can alter the internal microclimate, making it necessary to assess their impacts on thermal conditions, airflow patterns, and overall environmental suitability for crop growth. This study presents an integrated assessment of microclimatic behavior and energy performance of a photovoltaic greenhouse using computational fluid dynamics (CFD) simulations coupled with a solar energy generation analysis. A three-dimensional CFD model was developed to evaluate the spatial distribution of air temperature, airflow velocity, and ventilation patterns under three different photovoltaic shading levels applied to the greenhouse roof. Boundary conditions were defined using representative climatic data for the Bogotá Savanna, allowing the simulation of realistic operating scenarios. In parallel, the electrical energy generation potential of the photovoltaic system was estimated based on local solar radiation conditions, enabling an evaluation of the balance between microclimate modification and energy production. The results highlight that photovoltaic shading significantly influences the internal thermal stratification, air circulation, and microclimate uniformity. Moderate shading levels contribute to reducing excessive thermal loads while maintaining adequate ventilation, whereas higher shading intensities may lead to localized temperature gradients and reduced air movement. From an energy perspective, the photovoltaic system demonstrates a meaningful capacity to supply a portion of the greenhouse’s energy demand, supporting self-consumption strategies. Overall, the findings demonstrate that the combined use of CFD modeling and energy analysis provides a robust framework for optimizing photovoltaic greenhouse designs, facilitating informed decision-making that balances crop microclimate requirements with renewable energy generation in high-altitude tropical environments.

Renewable energy systems are increasingly critical for achieving decarbonization and long-term energy security, particularly in rural regions with abundant local resources. While solar and wind technologies have become cost-competitive, their intermittency limits reliability when deployed independently. Biomass, by contrast, offers dispatchable renewable power but faces economic challenges related to feedstock logistics. This study evaluates a biomass-led hybrid renewable energy system (HRES) for Grenada County, Mississippi, integrating biomass (feedstock includes tree species, including softwoods such as loblolly and shortleaf pine, and hardwoods such as white and red oak, ash, beech, sweetgum, cottonwood, poplar, hickory, and others within a 45-mile radius considering transport costs), solar photovoltaic (PV), and wind resources to enhance system reliability and reduce environmental impacts. System performance and optimization were assessed using the System Advisor Model (SAM) and the Hybrid Optimization of Multiple Energy Resources (HOMER). The proposed configuration comprises approximately 80% biomass, 10% solar PV, and the remaining share from wind, producing a total annual electricity output of about 423 GWh sufficient to meet regional demand which exceeds domestic, industrial and other energy demands of the county. The subsystem levelized cost of energy (LCOE) was estimated at 12.10 cents/kWh for biomass, 4.07 cents/kWh for solar PV, and 8.62 cents/kWh for wind, with the overall hybrid cost influenced primarily by biomass feedstock transportation and storage. Environmental impact assessment (LCA) based on U.S. EPA eGRID and IPCC factors indicates that the hybrid system achieves a weighted emission intensity of approximately 28.4 kg CO₂-eq/MWh, representing a reduction of over 94% compared to the regional grid. When scaled to annual generation, this corresponds to roughly 197,000 metric tons of avoided CO₂-equivalent emissions per year, alongside 80–95% reductions in acidification and eutrophication impacts. The results demonstrate that biomass-anchored hybrid systems can provide a reliable, low-carbon pathway for rural energy development, with further cost reductions achievable through targeted policy incentives and financing support. Overall, the findings from this study substantiate the system’s value proposition as context-responsive rather than universally optimal: regions with comparable resource conditions and similar rural development objectives may adapt the framework, provided that ecological limits, institutional capacity, and feedstock governance are explicitly addressed.

Epoxides serve as important intermediates for producing essential industrial and chemical substances, including plastics, resins, coatings, and pharmaceuticals. The sustainability and efficiency of an epoxidation process were significantly enhanced in this work by using molybdenum(VI) catalyst immobilised on polybezimidazole PBI.Mo. tert-Butyl hydroperoxide (TBHP) was selected as an oxidising agent to reduce waste generation and the formation of corrosive byproducts. In this work, continuous epoxidation of 1,7-octadiene was carried out in a flow reactor, which enhances heat and mass transfer efficiency and provides greater control over reaction conditions.

Optimisation of the epoxidation process was conducted by examining how reaction temperature, molar ratio of alkene to TBHP and feed flow rate affect epoxide production. To analyse how varying key parameters influence reaction outcome, the Response Surface Methodology employing a Box–Behnken Design (BBD) was implemented.

A Mo(VI) catalyst immobilised on polybenzimidazole was prepared and characterised. To assess the combined influence of different parameters on epoxide production, experiments were designed through RSM employing a Box–Behnken design.

The optimal reaction condition for the epoxidation of 1,7-octadiene was identified through the optimisation analysis tool in Design Expert. According to the numerical optimisation technique, the maximum yield of 1,2-epoxy-7-octene is 59.52% at an alkene to TBHP molar ratio of 9.650:1, a reaction temperature of 352 K, and a feed flow rate of 0.1 mL/min. The prediction was validated under the optimising condition and epoxide yield was found to be 59.15%, which was comparable to the expected optimal response of 59.52%.

This study shows how the PBI.Mo complex can be utilised as an efficient and environmentally friendly catalyst. The results of this investigation also show that a thorough assessment of reaction parameters can play an important role in improving the performance of alkene epoxidation under continuous flow condition.

Reliable electricity supply remains limited in conflict-affected rural regions of Somalia, constraining socio-economic development and service delivery. This study designs and evaluates a hybrid photovoltaic–diesel generator–battery storage (PV–DG–BS) microgrid through techno-economic optimization, sensitivity analysis, resilience assessment, and environmental performance. Using HOMER Pro simulations supported by site data and a load-scaling approach, five system designs were evaluated, combining conventional resources, particularly diesel, with renewable energy sources, particularly solar, alongside a battery storage solution. The study identified an optimal fixed architecture comprising 12,000 kW of PV, ≈38.3 MWh of battery storage, a 5,397-kW converter, and three of 2,000-kW diesel generators operated in a load-following mode. The optimal hybrid system produces ≈21.54 GWh/yr with a renewable fraction of ≈81.3%, indicating that the majority of annual energy is supplied by PV plus storage and achieves a competitive levelized cost of energy (LCOE ≈ 0.167 USD/kWh). Compared to a diesel-only baseline, annual diesel uses falls from ≈5.18 million L to ≈0.973 million L (≈81.2% reduction). Corresponding CO₂ emissions drop from 13,584,108 kg/yr to 2,550,864 kg/yr, saving ≈11,033 tCO₂/yr. CO₂ intensity improves from 0.700 kgCO₂/kWh to 0.118 kgCO₂/kWh. One-at-a-time sensitivity runs show that LCOE is most sensitive to the discount rate and diesel price; PV and battery cost changes have a lesser impact within the tested bands. Resilience testing under realistic stress cases (solar −10% and −20%, load +15%, single DG outage, and battery −20% capacity) shows the system maintains near-full reliability. Unmet load is effectively zero for all scenarios except the single-DG outage, which caused a very small unmet fraction (≈0.0328%). Battery cycling (~203 cycles/yr) is consistent with daily peak-shaving use. The study concludes that the PV/DG/BS hybrid is technically feasible, environmentally safe, and economically robust under realistic assumptions; it recommends integrating wind and hydrogen-based storage to further increase the renewable fraction, investigating grid-connected and net-metering operations which may enhance energy availability and minimize curtailment, and evaluating socio-economic impacts.

Abstract

Introduction

The open burning of agricultural residues and lack of access to affordable energy remains a major challenge in the rural areas of the developing countries. One million tons of crop residue like rice husk, wheat straw and cotton stalks are wasted each year, contributing to excessive air pollution, greenhouse gases and wasted bioenergy. Briquetting of charcoal is a potential waste-to-energy conversion platform where low density agricultural byproducts can be converted into more clean and high energy density solid fuels to be used in decentralized rural energy use. This paper is aimed at analyzing the design, development and performance analysis of a low cost manually operated charcoal briquetting system, which is targeted towards the smallholder farmers with special attention being on the fuel quality, system productivity and its environmental performance.

Methods

The constructed system comprises of drum kiln to carbonize biomass, a size reduction unit to prepare charcoal and manually operated compaction press, which is made of locally available materials. Agricultural waste is burned in the presence of limited oxygen and reduced to fine charcoal dust and then mixed with other natural binders like starch and molasses. The briquettes obtained are tested in terms of bulk density, compressive strength, moisture content, calorific value, burning time and smoke emission. The controlled burning tests that are used to evaluate combustion performance and emission properties are conducted by use of the portable Testo-350 gas analyzer to compare between briquettes and the traditional biomass fuels.

Results

The system yields 25-35 kg/hr of charcoal briquettes with bulk densities of 650-820 kg /m³ and calorific values of 18-24 MJ/kg. The briquettes have a lifespan of 30-45 percent longer and much lower smoke emissions as compared to raw biomass fuels. According to the availability of crop residues in the region and the potential of their utilization as briquettes, the system suggests that 30-40 percent of agricultural residues can be diverted against open field burning. Moreover, the household fuel expenses will decrease by 25-35 percent. These findings demonstrate that biomass briquettes can be used as a dependable renewable solid fuel which can partially substitute the conventional fuels like firewood and coal in decentralized rural energy systems.

Conclusions

In general, the subject of manual charcoal briquetting has been demonstrated to be a technically and economically viable to rural energy solution. At the same time, it can serve to manage crop residues and domestic energy demands in households. The research shows the significance of emission controlled carbonization equipment and standardized production of briquette to enhance energy efficiency, minimize environmental pollution, and promote the use of briquette by rural populations.

Dry Reforming of Methane (DRM) is a promising route for syngas production while valorizing and eliminating important greenhouse gases such as CO₂ and CH₄. However, its high endothermicity demands efficient heat transfer at temperatures above 1073 K, and catalyst deactivation by coking remains a major challenge. In particular, we are analysing the use of liquid metal reaction media to avoid coking accumulation. Developing reliable process models for such reactor concepts requires the integration of detailed reaction kinetics with robust process simulation tools. This work presents a methodological framework for implementing complex, multi-step Langmuir–Hinshelwood (L-H) kinetic models. The framework is demonstrated through a case study on DRM coupled with the Reverse Water-Gas Shift (RWGS) reaction, tailored for a hypothetical liquid metal catalytic environment. A detailed 23-step surface mechanism is simplified by assuming the dissociation of adsorbed CH₄ and the surface reaction between adsorbed CO₂ and H as the Rate-Determining Steps (RDSs) for DRM and RWGS, respectively. It incorporates the unique properties of liquid metals, such as weak adsorption and carbon dissolution into the bulk, to minimize coke formation terms. The derived rate equations are implemented in custom Python scripts to model an isothermal Plug-Flow Reactor (PFR), using literature-derived kinetic parameters as a baseline. However, the calculation runs into the lack of experimental data that allow its validation, which becomes a critical aspect to be able to estimate the chemical kinetics of the reaction itself. As a result, a series of experiments are proposed to validate these design tools for DRM in liquid metal. The results highlight the framework's capability for preliminary performance assessment and sensitivity analysis. This study provides a foundational kinetic framework open-access workflow for incorporating advanced heterogeneous kinetics into process simulation, serving as a template for evaluating novel reactor designs where commercial simulator options are limited or cost-prohibitive.

The core contribution of this work is procedural and computational. It provides a clear, reproducible pathway from fundamental kinetic theory to executable process simulation. Key achievements of the framework include

- The seamless integration of user-defined kinetic expressions within steady-state reactor models.
- The ability to model coupled reaction networks (DRM and RWGS) with proper thermodynamic consistency.
- The facilitation of sensitivity analyses, crucial for identifying critical parameters (e.g., adsorption constants) for future experimental campaigns.

Future work should focus on applying this framework to systems with available experimental data for full validation and the adjusted kinetic parameters for specific liquid metal alloys. Furthermore, model extension to adiabatic and multi-stage reactor configurations, coupled with techno-economic analysis, is essential to advance the industrial feasibility of this promising technology for sustainable syngas production. Critical technical milestones include the construction of fluid-mechanic demonstrators, the execution of high-temperature reaction experiments, and the development of specialized structural materials and carbon extraction systems capable of sustained high-temperature operation.

Interest in biobutanol as a top-rated biofuel and industrial solvent has increased due to its high energy density, low water-absorbing properties, and compatibility with existing fuel infrastructure systems. Converting butyric acid derived from biomass to butanol using species of Clostridium presents a promising approach for recycling carbon and valorising waste. Despite advances, challenges persist due to low conversion efficiency, product inhibition, and metabolic limitations, hindering large-scale implementation. This research examines the microbial conversion of butyric acid into butanol by solventogenic Clostridium species in a controlled anaerobic fermentation process. The process was optimized by altering pH levels, initial butyric acid concentrations, availability of electron donors, and the duration of fermentation. Metabolic flux was redirected towards solventogenesis by controlling redox balance and selectively supplementing nutrients. Substrate consumption and product formation were quantified using analytical techniques such as gas chromatography and high-performance liquid chromatography. Significant improvements to fermentation conditions led to a substantial increase in butanol production, resulting in high butanol selectivity and a decrease in the formation of by-products. The fermentation of butyric acid utilized a two-step process. The first stage process of upgrading is esterification, where the butyric acid is reacted with an alcohol. Butyric acid is separated from methanol in the presence of an acid catalyst to form methyl butyrate and water. The second step is hydrogenolysis of the butyrate ester in the presence of Hydrogen and a metal catalyst. The ester C-O bond is broken by hydrogenolysis, and the intermediates are hydrogenated to obtain biobutanol, and the corresponding alcohol utilized in the esterification is reusable. Reaction temperatures are normally between 180 and 260°C at high hydrogen pressures. This process reduced fermentation time and enhanced carbon efficiency relative to conventional acetone-butanol-ethanol (ABE) fermentation. The results show that Clostridium sp. can effectively re-uptake butyric acid and convert it into butanol, which suggests a strong potential for combining acidogenic and solventogenic bioprocessing methods. The conversion of butyric acid to butanol by Clostridium sp. constitutes a feasible and environmentally friendly biotechnological process for the production of sophisticated biofuels. This approach underpins circular bioeconomy principles by integrating waste-derived volatile fatty acids with renewable fuel production. Advances in metabolic engineering and process integration could make biobutanol production more scalable and economically viable.

The rapid transition toward power systems with high shares of renewable energy raises fundamental questions about how system adequacy, reliability, and resource value should be assessed in a decarbonized electricity sector. While renewable sources such as wind and solar photovoltaics provide clear environmental benefits, their variability, weather dependence, and limited controllability challenge conventional approaches to capacity planning and adequacy assessment. These challenges are further intensified by increasing electrification, sector coupling, and the growing presence of distributed and hybrid energy resources.

Classical resource adequacy frameworks were originally developed for power systems dominated by dispatchable thermal generation. Under assumptions of independent forced outages and statistically stationary demand, probabilistic metrics such as Loss of Load Probability (LOLP), Loss of Load Expectation (LOLE), Expected Unserved Energy (EUE), and Effective Load Carrying Capability (ELCC) have long been used to quantify system reliability. However, the increasing penetration of variable renewable energy introduces weather-driven variability, correlated generation patterns, and climate-related non-stationarity, challenging these foundational assumptions.

This systematic review evaluates whether classical probabilistic adequacy metrics remain structurally valid under high renewable penetration and examines how modelling approaches are evolving to represent correlated renewable variability, storage dynamics, and climate uncertainty. Following PRISMA 2020 guidelines, literature searches were conducted in Scopus, Web of Science, IEEE Xplore, and ScienceDirect for peer-reviewed studies published between 2000 and 2025. Preliminary screening identified 300 records, of which 30 full-text articles were selected for detailed analysis.

Early results indicate that while traditional adequacy metrics remain widely used, their implementation increasingly relies on chronological Monte Carlo simulation and weather-correlated modeling. Significant methodological heterogeneity persists, particularly in ELCC calculation, the representation of multi-day renewable droughts, and the definitions of reliability standards. These findings suggest that adequacy metrics remain relevant but require adapted modeling frameworks for renewable-dominant systems.

Introduction

Perovskite solar cells (PSCs) represent a transformative development in photovoltaics due to their high power conversion efficiencies (PCEs), solution-processable fabrication, and low material cost. Since their inception, PSCs have witnessed a dramatic improvement in PCE from 3.8% in 2009 to over 27% in certified single-junction devices, with perovskite–silicon tandem cells now exceeding 33.9% efficiency. Despite this progress, challenges such as poor long-term stability, lead toxicity, and scalability hinder their commercial deployment.

Methodology

This study synthesizes recent advancements in materials engineering, device architecture, and integration techniques. The materials analyzed include mixed-cation and halide perovskites (e.g., Csx(FA₀.₄MA₀.₆)₁₋ₓPbI₂.₈Br₀.₂), lead-free alternatives (e.g., Cs₂TiBr₆), and 2D/3D hybrid structures. Evaluation methods span experimental fabrication outcomes, theoretical simulations, and comparative analyses of transport layers (e.g., ZnO, CuSbS₂, MBene) and encapsulation techniques (e.g., polymeric coatings, self-healing systems).

Results

The incorporation of dimensional and compositional engineering strategies—such as 2D Dion–Jacobson capping layers, covalent organic frameworks (COFs), and transition metal dichalcogenides (TMDs)—has led to marked improvements in stability and charge transport. Tandem and bifacial architectures have enabled PCEs exceeding 30%, while simulation studies indicate the potential for >33% with anti-reflective coatings. Lead-free compositions like Cs₂TiBr₆ have achieved simulated PCEs near 27%, demonstrating comparable promise without toxicity concerns. Advanced hole/electron transport layers, including SnO₂-MBene and C60-LiF-SnO₂ combinations, have significantly reduced charge recombination losses. Scalable manufacturing processes, such as blade coating and vapor-phase deposition, are facilitating the transition toward flexible and building-integrated photovoltaics (BIPVs). Encapsulation strategies have improved operational durability under moisture and UV exposure, while self-healing materials extend functional lifespan.

Conclusion

PSCs have reached the forefront of next-generation solar technology, achieving record-breaking efficiencies and notable breakthroughs in material science. However, further innovation is required to overcome issues of long-term environmental stability, reproducibility in large-scale fabrication, and lead toxicity. Continued interdisciplinary research into lead-free compositions, interface engineering, and scalable device processing will be crucial to enable the successful commercialization of PSCs. The integration of perovskites into tandem, flexible, and multifunctional platforms represents the next frontier in photovoltaic evolution.