Integration of renewable energy and waste heat resources could effectively reduce emissions and the production cost in methane production power plants. The objective of this study is to conduct a technoeconomic analysis of an Iraqi methanol production facility using a combination of energy resources of waste gas from Al-Fallujah white cement factory, solar and wind energy. It is hypothesized that the carbon dioxide present in the flue gas could be extracted using solar and wind turbine energy in a carbon capture unit in the hydrogen plant. Methanol fuel is then produced in the methanol plant from the combined sources. The amount of energy and the number of solar panels or wind turbines (WT) needed to supply this energy requirement were estimated using the Engineering Equation Solver (EES), and then the environmental impact of the methanol plant was assessed. The efficiencies of renewable energy PV, WT, methanol plants, and methanol fuel were predicted as 21%, 35%, 16.26%, and 58.72%, respectively. The electrolyzers’ efficiency was 78.2% at their ideal density of 2.2 kA/m$^2$. With a production capacity of 34,530 million tons of methanol, the total cost to operate the plant for 30 years for each of the PV plants and WT was found to be \$9.46 billion and \$5.291 billion, respectively. This translates to 0.4131 \$/kg methane for the PV plant and 0.2413 \$/kg methane for the wind power plant. In terms of the environment, there is a daily 3,894 tons of collected CO$_2$ emissions and 3,306 tons of mitigation. The results show that the current facility can compete with facilities that produce clean synthetic fuel.

Mini hydropower plants (MHPs) play a vital role in providing sustainable electricity to off-grid rural communities in Indonesia. This study optimizes the hydraulic performance of the penstock system for the Way Melesom MHP in Pesisir Barat, Lampung. Using a conservative design discharge of 0.822 m³/s, derived from the F.J. Mock rainfall–runoff model and Flow Duration Curve (Q₇₀) analysis, hydraulic modeling was conducted using the Darcy–Weisbach and Hazen–Williams equations for four pipe diameters (DN400–DN700). The results show that increasing the pipe diameter reduces headloss and increases net head and power output, with diminishing efficiency gains beyond DN600. The DN600 configuration achieves an optimal balance—yielding a velocity of 2.91 m/s, headloss of 3.45 m, and a net head of 61.81 m, corresponding to an estimated output of 0.45 MW (2.76 GWh/year). This capacity can supply electricity to approximately 2,300 rural households, or up to 3,000 customers (450 VA each), supporting 10–12 small villages under an off-grid distribution network. The analysis confirms that DN600 provides the best technical–economic trade-off, recovering 95% of the gross head (65.26 m) with 90% hydraulic efficiency. The study highlights the importance of integrating hydrological, hydraulic, and energy modeling for optimizing closed-conduit systems in small-scale hydropower, ensuring both engineering efficiency and sustainable rural electrification.

This study introduces a new framework, PACBDHTE, designed to evaluate materials for fusion reactor applications. To provide an integrated assessment that encompasses radiation damage, hydrogen behavior, transmutation effects, and material erosion within a unified evaluation scheme. The methodology includes evaluation Displacement per Atom (DPA) calculations, hydrogen retention analysis, transmutation assessments, and erosion rate determinations. The results identified SiC and WC-Be are strong candidates due to their exceptional hydrogen retention capabilities. Tungsten-based materials are competitive, but careful consideration is needed for 316L stainless steel due to lower hydrogen retention. additionally, Cu(I)-functionalized metal–organic frameworks (MOFs), such as Cu(I)-MFU-4l, show promising selectivity for hydrogen isotope separation which can support more efficient fusion fuel-cycle management. Overall, the findings highlight erosion rates are critical for material longevity, emphasizing the need for continuous monitoring. Overall, the study contributes to safe and efficient fusion energy technology.

This research examines The Electron Energy Distribution Function (EEDF) of electrons in plasma discharge for (CHF$_3$-He) gas combinations. The Fortran programming language was used to solve the Boltzmann equation. A two-term approximation was used to solve the Boltzmann transport equation for both pure gases and mixtures. Using this method of solution, the electron energy distribution function was computed, and electric transport parameters were evaluated with range of E/N varying from (10–600) Td. The electron energy distribution function of the CHF$_3$-He gas mixture is nearly Maxwellian at E/N values (10–20) Td, the distribution function is non-Maxwellian when E/N is raising. Also, the energy values of the mixtures largely depend on the transport energy between electron and molecule through collisions. In compared to mixtures, Helium gas has a high energy characteristic. At higher helium ratios, the mean electron energy to mixture is increasing. The mean electron energy in a gas mixture (35% CHF$_3$ + 65% He) and the behavior variation in electron mobility at this ratio both have larger values than other ratios.

Carbon dioxide emissions from power plants and industrial producers are a major driver of global warming, leading to rising temperatures and numerous adverse impacts on ecosystems and human life. In response, various strategies have been developed to mitigate greenhouse gas emissions. This review paper examines the three main stages of energy conversion for carbon dioxide capture: pre-combustion, oxy-fuel combustion, and post-combustion, with particular emphasis on the latter. Several capture techniques have been explored, including chemical and physical absorption, membranes, adsorption on porous materials, and cryogenic freezing. Among these, membrane-based methods have attracted significant attention due to their advantages in energy efficiency, operational simplicity, and potential integration with hybrid systems. Comparing the efficiency of different capture technologies, membranes achieve 85–90% efficiency at a lower cost (\$25–45/ton CO$_2$), while deep cooling technology boasts high purity ($>$99%) but comes at the cost of high energy consumption ($>$3.5 GJ/ton CO$_2$). Absorption technology, on the other hand, ranges between 90–95% efficiency at a cost of \$40–60/ton CO$_2$. Membranes have been successfully combined with absorption, desorption, and cryogenic processes to achieve higher purity in CO$_2$ capture. This study reviews twenty research papers on membrane technology, focusing on hybrid membrane systems and their performance. Carbon capture and storage (CCS) is widely recognized as a key strategy for achieving climate goals by reducing carbon emissions from thermal energy production and industrial processes, while also enabling the net removal of CO$_2$ from the atmosphere.

This study presents the development and performance evaluation of a photoelectrochemical (PEC) cell designed for sustainable hydrogen production, emphasizing a cost-effective and reproducible approach to clean energy generation. The PEC system was fabricated using an n-type TiO$_2$ photoanode and Pt cathode in an aqueous Na$_2$SO$_4$ electrolyte (0.5 M), operating under simulated solar irradiation of 100 mW/cm$^2$ (AM 1.5 G) within a controlled temperature range of 25–45 ℃. Experimental testing demonstrated that the system sustained hydrogen evolution through an automated electrolyte refilling and pump control mechanism, achieving 51% H$_2$ saturation within an average of 2.8 seconds over 172 activation cycles, indicating responsive system logic. However, prolonged operation led to efficiency decline, with pump activation time extending to 833 seconds and only 56% hydrogen recovery, signifying material and control degradation. The temperature monitoring subsystem malfunctioned, registering persistent –127 ℃ readings, which impeded accurate thermal regulation and safety evaluation. Sensor drift and inconsistent pump actuation were also observed, reflecting calibration deficiencies. Three operational phases were identified—initial instability (0–300 s), stabilization (300–600 s), and performance degradation ($\geq$800 s). Overall, while the PEC system demonstrates promising short-term hydrogen generation efficiency under defined light and electrolyte conditions, long-term stability remains constrained by electrode durability, thermal control accuracy, and system integration challenges, requiring further optimization for sustained hydrogen production.

This review of the current literature highlights the barriers present within cavities and their contribution to heat dissipation and cooling of various activities. This study shows a set of factors that affect the function of the obstacle (shape, length, size, thickness, and location of the obstacles). The variation in boundary conditions between obstacles and cavity walls has opened up broad horizons for scientific research in the field of heat transfer (HT) and fluid flow. Despite significant progress, research gaps remain. Most previous studies have focused on simple shaped obstacles within cavities with uniform boundaries. There is a distinct lack of studies exploring the effect of complex such as U/L/H shapes or orientable obstacles within complex cavities or under dynamic conditions such as non-uniform heating or varying magnetic fields. It was found that the Nusselt number increased by 15.56% depending on the shape of the internal obstacle, which gives an advantage to some obstacle shapes over others and highlights the importance of choosing the obstacle and cavity shape so that the best HT is obtained. This study is the first to compare simple and complex shapes of obstacles, and this is the innovative point of this review.

The integration of variable renewable energy sources has driven research into the flexibility capabilities of power systems, which are characterized by high variability and uncertainty. Flexibility refers to a power system's ability to respond to changes in demand and generation across different time frames. This concept has been extensively studied in the literature, so the great variety of flexibility definitions and market approaches is a challenge for new stakeholders interested in the field. Establishing a market design that promotes the participation of flexible sources and ensures proper compensation is essential. This paper provides a comprehensive review of market designs proposed in the literature to enhance power system flexibility and approaches for quantifying its economic value. The study follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology for the identification, screening, and inclusion of documents, using Web of Science (WOS) and Scopus databases. After analyzing 102 papers, including 50 literature reviews, common approaches and concepts were identified and categorized into demand response, storage, market design, and other general frameworks. Among the market design proposals, the Flexible Ramp Products and Local Flexibility Markets are highlighted, along with an analysis of how to value this flexibility. This study complements existing literature by grouping the most relevant literature on power system flexibility and its valuation in energy markets, clarifying how market designs contribute to addressing renewable integration challenges—essential for future energy system planning with increased renewable energy penetration.

As environmental concern increases and fossil fuel reserves dwindle, biodiesel has emerged as an alternative sustainable, renewable, and biodegradable fuel to supply diesel engines. Amongst the various sources of raw materials used in biodiesel production, locally sourced sunflower oil presents a viable alternative, especially in countries experiencing problems with energy security and emission reduction, such as Iraq. In this work, the performance and emissions of four-cylinder direct injection diesel engine fueled with locally made Iraqi sunflower oil biodiesel were investigated. The biodiesel was produced with a transesterified reaction, and it was evaluated in blends as B20, B50 and pure (B100) in comparison to diesel fuel under several operating conditions of speed (1250–3000 rpm) and load (4.3–90 kN/m²). Experimental results showed that the environmental impact of water injection was significant: CO emissions decreased by almost 50%, unburned hydrocarbons by 45% and carbon dioxide by 33%, without neglecting reduction of exhaust temperature and engine noise. On the other hand, the calorific value of biodiesel is lower than that for diesel and caused high Brake specific fuel consumption (BSFC) up to its peak at 12% for B100. $\mathrm{NO}_{\mathrm{x}}$ increased by about 21% as a result of improved oxygen availability and higher in cylinder temperatures. Among the blends studies, B20 demonstrated promising balancing of emissions reductions and thermal efficiency with no mechanical modifications. However, some limitations remain and should be explored in further studies. It is recommended to combine durability testing, techno-economic analysis and on-road tests in the future in order to fulfill international emission control legislations and for environment-friendly application of biodiesel in Iraq power and transportation services.

Bio-oil from lignocellulosic biomass pyrolysis cannot be applied as biofuel because it is generally corrosive due to its high organic acid content. The organic acid content of heavy fractions can be reduced by fractionation and by esterification with alcohol to form ester compounds. This study aims to produce high-quality fuel by optimizing the bio-oil: methanol ratio using a magnesium metal oxide modified H-zeolite catalyst (HAAZ/MgO) to convert sago dregs bio-oil. This study was carried out in several stages: pyrocatalytic sago dregs were heated to 350–500 °C, then the bio-oil was filtered and fractionally distilled at 91–110 °C. HAAZ/MgO catalyst was successfully synthesized according to Fourier transform infrared spectroscopy (FTIR) characterization, showing absorption at 3300–3700 cm^-1, the emergence of hydroxyl group (-OH) stretching vibrations originating from silanol groups (Si-OH) and Brønsted acid sites (Si-OH-Al), 1641–1649 cm-1 as H-O-H bending vibrations, 1053–1223 cm⁻¹ asymmetric stretching vibrations of Si-O-Si and Si-O-Al bonds, and 1350–1450 cm⁻¹ indicating the presence of MgO-zeolite. The X-ray diffraction (XRD) spectrum of HAAZ/MgO shows diffraction peaks at 2θ = 20.86°, 25.67°, 26.65°, and 27.74°. The presence of MgO does not damage the HAAZ structure and is evenly dispersed. The fractionated distillate was esterified by reflux at 65 °C. at the ratio of bio-oil distillate to methanol (1:6, 1:8, and 1:10) using HAAZ/MgO catalyst. The esterified biofuel showed the best yield at a 1:10 ratio, with 72.22 ± 1.11% (v/v). The esterification process demonstrated the HAAZ/MgO catalyst's good performance, yielding dimethyl and methyl esters. In addition, the physicochemical properties of bio-oil, including pH, viscosity, and API gravity, increased significantly after esterification, while water content, density, specific gravity, and viscosity decreased. Meanwhile, the higher heating value (HHV) of the esterified biofuel increased from 43.55 to 45.15 MJ/kg. Improvements in these parameters indicate that the esterification process plays an important role in enhancing biofuel quality, making it a feasible and efficient renewable energy source.

Phase change materials (PCMs) are highly effective in storing and releasing thermal energy during phase transitions, making them critical for thermal energy storage (TES) systems, particularly for renewable energy sources such as solar and wind. They have been reported in energy storage, especially in renewable energy systems such as solar and wind. However, despite their potential, their practical use is limited by low thermal conductivity and slow heat transfer rates. These limitations reduce the efficiency of PCMs in applications requiring rapid thermal responses, such as solar thermal storage and electric vehicle (EV) battery cooling. This review synthesizes and compares recent numerical and experimental studies on PCM enhancement techniques. A significant challenge across these studies is the lack of uniform operating conditions, which complicates the identification of the most effective methods for specific TES applications. The review highlights several strategies to improve PCM performance, including the use of metal foams (MFs), nanoparticles (NPs), and fins. MF has been shown to significantly improve thermal conductivity, increasing it by up to 200% for calcium chloride hexahydrate and 100% for paraffin, while also reducing melting times by 84.9% compared to pure paraffin. NPs, like copper oxide (CuO) and aluminum oxide (Al$_2$O$_3$), can enhance thermal conductivity by up to 122% relative to pure PCM. However, higher concentrations of NPs may increase viscosity, which slightly hinders heat transfer. Fins provide a cost-effective method to enhance heat transfer. The addition of fins has been shown to reduce melting times by 65.5% at 3600 seconds, making them an ideal choice for applications where cost is a key consideration. Hybrid systems combining MFs and NPs achieve the greatest performance improvements. For instance, using 3% NPs and a 60% porosity in copper MF increases thermal conductivity by 37.7% and reduces the melting time by 87.03%. Further improvements are observed when using MF with 85–90% porosity and 10–15% NPs, achieving a 90% reduction in melting time. This demonstrates the synergistic effect of combining these two techniques. In conclusion, hybrid methods combining MFs and NPs offer an efficient and cost-effective approach for enhancing PCM performance in TES applications. By integrating the strengths of these techniques, multiple performance limitations can be addressed simultaneously, providing a viable solution for large-scale TES systems.

Photovoltaic thermal (PVT) systems have emerged as a promising solution for enhancing overall energy efficiency by simultaneously generating electricity and heat, addressing the performance limitations of conventional photovoltaic modules operating under elevated temperatures. This study reviews thermal management strategies, techno-economic feasibility, and environmental sustainability of PVT systems through a comprehensive bibliometric and technical analysis. A systematic approach was employed, integrating bibliometric mapping of global research trends with a detailed classification of thermal management technologies, including air cooling, water cooling, nanofluids, phase change materials (PCMs), heat pipes, and refrigerant-based systems. The review further examines cost performance trade-offs and life-cycle environmental impacts to evaluate the viability of large-scale implementation. Results indicate that advanced cooling approaches particularly nanofluid-enhanced systems and PCM composites effectively improve thermal conductivity and stabilize module temperatures, enabling combined electrical and thermal efficiencies exceeding 85% and, in some hybrid configurations, approaching 94%. Techno-economic assessments reveal that optimized system designs and integration with heat pumps can lower the levelized cost of energy and shorten payback periods, while environmental evaluations demonstrate reductions in carbon footprint and energy payback time. Despite these advantages, challenges persist regarding material stability, cost, and end-of-life recyclability. This study highlights the need for integrated optimization frameworks that account for energy, exergy, and life-cycle impacts. Future research should prioritize cost-effective nanomaterials, AI-driven control strategies, and advanced hybrid configurations to accelerate commercialization and support global decarbonization efforts.

The accelerated deployment of photovoltaic (PV) systems in Malaysia has raised critical concerns regarding end-of-life (EOL) panel waste, particularly in states like Kedah where large-scale solar installations are concentrated. Despite growing attention to solar energy, limited infrastructure and governance mechanisms exist for managing decommissioned PV panels. This study presents an integrated approach to optimizing EOL PV waste management in Kedah, Malaysia, by incorporating lifecycle-based environmental and economic analysis. With a projected increase in PV waste by 2034 and beyond, the research applies a combination of Life Cycle Assessment (LCA), Life Cycle Costing (LCC), Multi-Criteria Decision Analysis (MCDA), and Geographic Information Systems (GIS)-based modeling to assess and optimize each phase of the waste management process from uninstallation, transportation (T$_1$ and T$_2$), and collection center operations to recovery facilities (RF). Results show that optimized routing, strategic load consolidation, and selective frame dismantling at collection centers (CC) can reduce transport related emissions by up to 35% and operational costs by over 20%. The integration of Circular Economy (CE) principles and Extended Producer Responsibility (EPR) frameworks ensures material recovery (aluminum and silicon), improves traceability, and aligns the model with national regulatory standards. This research proposes a scalable, policy-aligned optimization framework that enhances environmental performance and cost efficiency in Malaysia's emerging PV waste sector.