Search Results (4,881)

Molten salts are increasingly regarded as promising fluids for high-temperature heat transfer, thermal energy storage, and advanced reaction processes, including concentrated solar power (CSP), molten salt oxidation (MSO), and next-generation nuclear reactors. Among these materials, the ternary eutectic mixture Li₂CO₃–Na₂CO₃–K₂CO₃ (32.12–33.36–34.52 wt%) has emerged as a leading candidate due to its wide operating temperature range and favourable thermodynamic properties. Despite its relevance, substantial inconsistencies and gaps remain in the available thermophysical property data, posing challenges for reliable design, modelling, and industrial deployment. This work revisits the Li₂CO₃–Na₂CO₃–K₂CO₃ eutectic through a critical assessment of the literature from its reported melting point at 670 K (397 °C) up to approximately 1200 K (927 °C). Using a methodology inspired by IUPAC-supported strategies previously applied to common liquids such as water and hydrocarbons, we examine the quantity, quality, and coherence of existing measurements. Reference correlations are proposed only where the data are sufficiently robust to justify them. The analysis highlights a pressing need for more accurate and comprehensive measurements—particularly for heat capacity, thermal conductivity, and viscosity—to enable the development of reliable standard reference correlations. Brief recommendations are given on the measurement methods that should be used in high-temperature measurements, namely for heat capacity, viscosity, and thermal conductivity. Reliable thermophysical property data for (LiNaK)₂CO₃ remain limited and inconsistent, despite its relevance for high-temperature energy applications. Density data are comparatively robust, but heat capacity, thermal conductivity, and viscosity still require high-accuracy measurements at elevated temperatures. Addressing these data deficiencies is essential for advancing the safe and efficient use of molten carbonates in high-temperature energy technologies. Full article

Third-generation photovoltaic (PV) technologies, such as dye-sensitized solar cells (DSSCs), organic solar cells (OSCs), quantum-dot solar cells (QDSSCs), and perovskite solar cells (PSCs), are characterized by properties that enable applications beyond conventional silicon-based devices. However, despite remarkable progress in third-generation solar cells, significant challenges related to efficiency, stability, scalability, and commercialization remain significant. The purpose of this review work was to summarize recent developments in third-generation photovoltaic technologies, including component materials design, configurations, performance data, limitations, and future research directions. The reported studies demonstrated crucial improvements in power conversion efficiency, which exceeded 15% for DSSC, 20% for OSC, 12% for QDSSC, and 26% for PSC. The key challenges to commercialization include further improvements in efficiency, better stability, and meeting the environmental requirements. Although important technological and environmental challenges remain, third-generation solar cells are expected to contribute to future sustainable energy systems due to their high efficiency potential, low-cost fabrication, and possible incorporation of environmentally friendly materials in the structure of the cells. The photovoltaic performance under indoor conditions and the aspect of a sustainable approach were identified as recent research trends. Full article

Thermal energy storage using suitable materials is a strategic solution for integrating renewable energy and decarbonising industrial processes. Current Power-to-Heat systems using solar salt rely on electric heaters; however, the low thermal conductivity of molten solar salt promotes localised hot spots, leading to material degradation and reduced performance. Microwave heating is a promising alternative due to its volumetric heating capability and compatibility with renewable electricity. Nevertheless, dielectric characterisation shows that molten solar salt behaves as a highly conductive ionic medium with significant dielectric losses, limiting microwave penetration and resulting in predominantly surface-localised heating. To investigate this limitation, two cavity configurations were analysed using multiphysics simulations and parametric design studies: a single-mode elliptical cavity operating at 915 MHz with an iris, and a quasi-cylindrical multimode cavity operating at 2.45 GHz for scalable applications. The coupled electromagnetic, fluid-flow, and thermal behaviour was evaluated through the resulting field distributions and heating patterns. Complementary experiments assessed microwave-transparent container materials and determined the emissivity of molten solar salt from thermographic measurements, highlighting key engineering considerations for integrating microwave heating into next-generation Power-to-Heat technologies. The results demonstrate that microwave heating of highly conductive molten solar salt is fundamentally constrained by the limited electromagnetic penetration depth, defining practical design limits for its integration into next-generation Power-to-Heat systems. Full article

Wave energy represents one of the most promising renewable sources due to its high energy density and predictable availability compared to wind and solar power. Despite its potential, technological exploitation remains challenging because of harsh marine environments, high installation and maintenance costs, and the absence of a dominant technology. This work presents a comprehensive review of wave energy conversion technologies and provides a detailed kinematic and dynamic analysis of a novel mechanical system designed to transform oscillatory linear motion into continuous unidirectional rotary motion, suitable for electricity generation. Particular focus is placed on the analytical modeling of the system, the design of a flywheel for energy stabilization, and performance evaluation. Results highlight the feasibility of the proposed configuration and its potential advantages compared to conventional hydraulic systems. Full article

Offshore floating photovoltaics (OFPVs) offer a promising route for expanding solar energy development from land and inland waters to marine space, particularly in China’s coastal regions where electricity demand, land-use constraints, offshore wind infrastructure, and photovoltaic manufacturing capacity are highly concentrated. This review examines the development status, structural concepts, hydrodynamic challenges, research methodologies, reliability issues, and future pathways of OFPV systems in China from the perspective of marine engineering. Demonstration projects, representative platform concepts, and recent studies on environmental loading, platform motion, multi-body interaction, connector and mooring responses, and hydroelastic behavior are systematically synthesized. The review shows that Chinese OFPV technology has progressed from conceptual exploration to prototype testing and sea-based validation, with flexible membrane, steel-frame, semi-submersible, tensioned floating-island, HDPE modular, and composite-material concepts under active investigation. However, mature and replicable engineering solutions remain limited. Key barriers include survivability under extreme sea states, fatigue reliability of large arrays, corrosion, biofouling, material degradation, insufficient long-term field data, and the lack of dedicated design standards. Future development should emphasize array-level hydrodynamic design, coupled connector–mooring optimization, life-cycle reliability assessment, full-scale monitoring, and integration with offshore wind, wave energy, floating breakwaters, aquaculture, and other marine energy systems. Full article

The global proliferation of plastic waste has made the search for sustainable chemical recycling strategies imperative to transition toward a circular bioeconomy. This study presents a dual-valorization approach for polylactic acid (PLA) waste, utilizing it both as a sustainable precursor for g-C₃N₄ catalyst synthesis and as a sacrificial agent for green hydrogen production via photoreforming. Platinum-modified graphitic carbon nitride catalysts were synthesized and evaluated using pure lactic acid and commercial PLA waste under solar-simulated irradiation. Results identified C₃N₄-NaOH-Pt as the most active material, while the simultaneous one-pot depolymerization/photoreforming of macroscopic PLA fragments exhibited a peak H₂ production rate of 1.5 mmol·h⁻¹·g⁻¹, remarkably surpassing both the pure monomer model and pre-depolymerized solutions. This enhanced performance is tentatively attributed to a “controlled release” mechanism that prevents catalyst surface saturation and minimizes light scattering effects inherent to fine powders. The study concludes that maintaining the macroscopic integrity of PLA waste provides a strategic advantage for chemical reforming by eliminating energy-intensive grinding and pretreatment. Future research into diverse operational and chemical parameters, including temperature and base-addition strategies, will be essential for scaling solar-driven upcycling technologies. Full article

Organic solar cells (OSCs) are a potential photovoltaic technology because they can be manufactured in scalable systems, are lightweight, and have mechanical flexibility. Power conversion efficiencies close to 20% have been achieved in recent years due to the quick development of donor–acceptor material systems. Better control over nanoscale shape and the creation of non-fullerene acceptors are major factors driving this advancement. Nevertheless, there are still complicated connections between morphology, interfacial energetics, and molecular structure. It is yet unclear how these elements interact to affect charge creation and transport. In this review, donor–acceptor interactions in organic solar cells are examined from a fundamental chemical and physical perspective. From conventional fullerene derivatives to contemporary non-fullerene acceptors, we first look at the development of acceptor materials. We demonstrate how molecular engineering has enhanced device efficiency, energy level adjustment, and light absorption. We then examine the energetic alignment at donor–acceptor interfaces, paying particular attention to charge-transfer state creation, border orbital offsets, and the factors influencing voltage losses. We also investigate how intermolecular interactions, including hydrogen bonding, π-π stacking, and noncovalent interactions involving heteroatoms, control electrical coupling and nanoscale shape in bulk heterojunction active layers. We also go over device engineering techniques including processor control, interface engineering, and bulk heterojunction architecture optimization. These tactics demonstrate how improved solar performance might result from molecular design. Lastly, we highlight new possibilities for next-generation OSCs, such as scalable production techniques, adaptive molecular design, and morphological stabilization. This work provides a strong framework for comprehending donor–acceptor interactions and for directing the careful design of high-performance organic photovoltaic systems by combining knowledge from molecular chemistry, morphological control, and device engineering. Full article

The rise in energy demand in Thailand due to constant economic growth coupled with reliance on limited natural gas and oil resources has led to an increased demand for alternative sources of energy. Therefore, this study aims at examining factors that influence the intention of adopting solar rooftop energy among households in Thailand through the integration of the theory of planned behavior (TPB) and the technology acceptance model (TAM). A quantitative research approach was adopted whereby data were obtained from 255 households in all parts of Thailand through questionnaires. The results reveal that attitude (β = 0.484, p < 0.001), perceived usefulness (β = 0.271, p < 0.05), and subjective norms (β = 0.257, p < 0.001) positively and significantly influence intention to use solar rooftop energy, collectively explaining 61% of the variance (R² = 0.61). Attitude proved to be the most significant predictor in this regard, underscoring the significance of the evaluative process of cognition and emotion for adopting certain behavior. This research makes a valuable contribution to the body of knowledge on renewable energy in that the TPB-TAM model has been empirically validated in a Thai household setting. In addition, the findings provide suggestive evidence of a mediating role of attitude in the link between perceived usefulness and intention, although this mediation finding should be interpreted with caution due to the conceptual overlap between these constructs and the absence of bootstrap confidence intervals. Future research is recommended to confirm this mediation pathway using formal bootstrap procedures. Full article

Hybrid nanofluids with enhanced thermal conductivity have emerged as promising candidates for efficient heat removal in advanced energy systems and next-generation thermal management technologies. In particular, the use of viscoelastic base fluids embedded with radiatively active nanoparticles enables improved thermal regulation in solar collectors, electronic cooling units, and high-temperature industrial processes. This study presents a comparative thermal investigation of mono- and hybrid nanofluids comprising the ferro-oxide (Fe₃O₄) and copper (Cu) metallic particles dispersed in ethylene glycol (C₂H₆O₂), under magnetohydrodynamic (MHD) viscoelastic flow over a stretched surface. Accurate modeling of heat and mass phenomena in such fluids arises from their growing application in advanced thermal systems, including cooling technologies, electronic devices, and renewable energy modules. Unlike conventional models, the current analysis incorporates the Cattaneo–Christov heat flux framework to capture non-Fourier thermal relaxation effects, alongside the influence of thermal radiation and solutal transport. The developed system is truncated into dimensionless form with the proper choice of appropriate quantities, whose solution methodology is based on the implementation of a Runge–Kutta scheme. Compiled observations suggest that the hybrid nanomaterial exhibits more pronounced thermal recovery, while mono nanofluid attributes lower impact. Moreover, increasing the viscoelastic and magnetic parameters leads to notable variations in temperature and concentration distributions. This work advances the current literature by simultaneously integrating viscoelastic rheology, dual nanoparticle suspensions, and non-classical heat conduction laws, providing new insights for optimizing thermal performance in engineering applications. Full article

This study presents a mathematics-based simulation model for designing, analyzing, and optimizing offshore green hydrogen stations powered by solar photovoltaic systems, applicable to any location worldwide. Developed in Python, the model integrates environmental, physical, and technological parameters to simulate and forecast hydrogen production via water electrolysis using alkaline (ALK) or proton exchange membrane (PEM) electrolyzers, combined with an adiabatic compressor that enhances energy storage and facilitates integration into smart grids. The five-phase modular methodology includes timeframe definition; estimation of solar electricity generation based on solar trajectory and the geographic orientation of photovoltaic panels; performance modeling of electrolyzers and compressors; and the integration of all components into a cohesive system. A case study demonstrates the model’s real-world applicability. Results from the Gulf of Cadiz case study show a substantial increase in solar energy capture in offshore environments due to reduced atmospheric pollution and sea-surface reflection. The reflected component is modeled as a function of sea-surface flatness. This reflection increases the daily average solar irradiance received by the photovoltaic panels by 8.44%. Under the modeled 2026 conditions and equivalent irradiance levels, the ALK electrolyzer produces 3.347% more hydrogen than the PEM electrolyzer. In addition, a 20% increase in electrolyzer efficiency raises hydrogen production by 32.35%, whereas the same increase in compressor efficiency improves production by 0.758%. These impacts directly correlate with proportional reductions in the photovoltaic panel surface area, driven by increased electricity generation capacity, which translates into smaller infrastructure needs. The model enables quantitative evaluation of trade-offs among solar irradiance, component performance, and system design. It supports cost reduction through optimized sizing and improved integration. This approach contributes to lowering the Levelized Cost of Electricity (LCOE) and promoting the viability of marine-based green hydrogen deployment. Full article

Transition metal oxides constitute an important materials platform for chromic phenomena because their optical response is strongly coupled to the changes in electronic structure, phase state, carrier concentration, and defect chemistry. This review discusses selected transition metal oxide thin films, with emphasis on VO₂ and other vanadium oxides, WO₃, NiO, and TiO₂. The review summarizes the structural and electronic characteristics of these representative oxide systems and highlights the role of phase composition, crystal structure, oxygen non-stoichiometry, and defect chemistry in determining their optical response. The main thin film preparation routes, including pulsed laser deposition, magnetron sputtering, sol–gel and aerosol spray methods, atomic layer deposition, chemical vapor deposition, electrochemical routes, and molecular beam epitaxy, are reviewed with respect their influence on obtained thin films. Particular attention is given to applications in thermochromic VO₂-and electrochromic WO₃/NiO-based smart windows, and transition metal oxide-based gasochromic hydrogen sensors. Key challenges related to transition temperature tuning, luminous transmittance, solar modulation, optical contrast, cycling stability, ion transport and large-area integration are also discussed. Overall this review provides a comparative overview of selected transition metal oxide thin films by connecting material chemistry and physics, thin film preparation technology and functionality. Full article

This exploratory pilot study analyzes the organizational and environmental determinants associated with stated intention to adopt biogas-solar microgrids within a circular bioeconomy framework. A quantitative, applied, cross-sectional design was used with 71 valid individual responses from participants linked to productive, agro-industrial, livestock, energy, and waste management organizations or projects, selected through nonprobabilistic convenience sampling. The analysis does not measure actual investment, implementation, or use; therefore, the results refer only to declared adoption intention and should not be generalized beyond the sample. The questionnaire measured perceived benefits, barriers, institutional conditions, financial feasibility, environmental value, organizational capabilities, and adoption intention. Content validity was supported by expert judgment, and psychometric reliability was assessed using Cronbach’s alpha and McDonald’s omega. Predictive modeling compared supervised classification, regression, and unsupervised segmentation techniques using train-test validation, cross-validation, and interpretability analyses. ExtraTrees achieved the best exploratory classification performance, with a test ROC-AUC of 0.889, while RandomForestRegressor showed the best regression performance; however, these values should be interpreted as sample-specific evidence rather than as a validated predictive tool. Organizational capabilities and environmental criteria emerged as the most influential predictors, and K-Means suggested two tentative readiness profiles with weak separation. The findings suggest that stated adoption intention is associated with a systemic configuration of organizational maturity, environmental legitimacy, financial feasibility, and institutional support, providing preliminary evidence for future larger sample validation and for decision-support discussions in sustainable energy transitions. Full article

The use of non-conventional systems for domestic wastewater management has gained attention in rural areas of the Global South, where centralised infrastructure is often limited. This study presents the design, construction, and pilot-scale evaluation of a solar still unit operated under passive and photovoltaic-assisted active modes as a separation and polishing component for domestic wastewater from a rural site in Barrancabermeja, Colombia. Performance was assessed through physicochemical and microbiological characterisation of influent wastewater and treated condensate, together with hourly monitoring of distillate production, water temperature, glass-cover temperature, and ambient conditions. Under passive operation, a theoretical distillation model was applied, empirically adjusted, and evaluated using MAE, RMSE, MAPE, and R². Under the tested conditions, indicative within-mode reductions reached 80.9% and 89.3% for chemical oxygen demand (COD), 95.6% and 93.8% for biochemical oxygen demand (BOD₅), and 94.0% and 94.4% for total suspended solids (TSS) under passive and active modes, respectively. Microbial indicators showed minimum estimated reductions above 99.9%, with faecal coliforms reduced to very low levels in passive mode and not detected in the analysed active-mode condensate sample. Maximum daily condensate production reached 1.445 L m⁻² day⁻¹ in passive mode and 2.262 L m⁻² day⁻¹ in active mode, confirming the low-flow nature of the unit. Approximately 50% of daily production occurred between 12:00 and 15:00 h. The model reproduced the main diurnal production pattern, although empirical correction was required. Overall, the unit may improve condensate quality under pilot-scale conditions and shows potential as a polishing component within decentralised, low-flow treatment trains. Full article

Solar energy has become one of the most important renewable energy sources for reducing dependence on conventional fossil-based energy systems. Rooftop photovoltaic (PV) installations play a key role in the expansion of solar energy, particularly in tropical countries such as Vietnam. This study experimentally investigates the effects of roof material, rear ventilation gap, PV technology, solar irradiance, and wind speed on the power conversion efficiency (PCE) of rooftop PV modules under tropical climatic conditions in Ho Chi Minh City, Vietnam. Three roof types (concrete, tiled, and corrugated metal), three rear ventilation gaps (10, 30, and 50 cm), and two PV technologies (monocrystalline and polycrystalline) were evaluated under real operating conditions. The results indicate that increased module temperature significantly reduces power output and PCE, even under high solar irradiance. PV modules installed on corrugated metal roofs exhibited the highest operating temperatures and the lowest efficiencies, whereas concrete and tiled roofs provided more favorable thermal conditions. Increasing the rear ventilation gap enhanced convective cooling, with the 30–50 cm configurations showing superior heat dissipation compared with the 10 cm configuration, particularly for corrugated metal roofs. The experimentally determined heat transfer coefficient ranged from 23.48 to 67.64 W m⁻² K⁻¹, exceeding the theoretical wind-based coefficient (16.86–17.22 W m⁻² K⁻¹), thereby indicating the contribution of mixed convection, radiative exchange, and roof–module thermal interactions. Monocrystalline modules consistently achieved slightly higher efficiencies than polycrystalline modules. The findings provide practical guidance for optimizing rooftop PV installations and improving energy yield in tropical climates. Full article