Search Results (358)

Although concentrated solar power (CSP) coupled with calcium looping (CaL) offers a promising avenue for efficient thermal chemical energy storage, calcium-based sorbents suffer from accelerated structural degradation and decreased CO₂ capture capacity during multiple cycles. This study used Density Functional Theory (DFT) calculations to investigate the mechanism by which Mg and Ni doping improves the adsorption/desorption performance of CaO. The DFT results indicate that Mg and Ni doping can effectively reduce the formation energy of oxygen vacancies on the CaO surface. Mg–Ni co-doping exhibits a significant synergistic effect, with the formation energy of oxygen vacancies reduced to 5.072 eV. Meanwhile, the O²⁻ diffusion energy barrier in the co-doped system was reduced to 2.692 eV, significantly improving the ion transport efficiency. In terms of CO₂ adsorption, Mg and Ni co-doping enhances the interaction between surface O atoms and CO₂, increasing the adsorption energy to −1.703 eV and forming a more stable CO₃²⁻ structure. For the desorption process, Mg and Ni co-doping restructured the CaCO₃ surface structure, reducing the CO₂ desorption energy barrier to 3.922 eV and significantly promoting carbonate decomposition. This work reveals, at the molecular level, how Mg and Ni doping optimizes adsorption–desorption in calcium-based materials, providing theoretical guidance for designing high-performance sorbents. Full article

Using solid particulates as a heat transfer medium for concentrated solar power (CSP) systems has many advantages, positioning them as a superior option compared with conventional heat transfer media such as steam, oil, air, and molten salt. However, a critical imperative lies in the comprehensive evaluation of the properties of potential solid particulates intended for utilization under such extreme thermal conditions. This paper undertakes an exhaustive examination of both ambient and high-temperature thermophysical properties of four naturally occurring particulate materials, Riyadh white sand, Riyadh red sand, Saudi olivine sand, and US olivine sand, and one well-known engineered particulate material. The parameters under scrutiny encompass loose bulk density, tapped bulk density, real density, sintering temperature, and thermal conductivity. The results reveal that the theoretical density decreases with the increase in temperature. The bulk density of solid particulates depends strongly on the particulate size distribution, as well as on the compaction. The tapped bulk density was found to be larger than the loose density for all particulates, as expected. The sintering test proved that Riyadh white sand is sintered at the highest temperature and pressure, 1300 °C and 50 MPa, respectively. US olivine sand was solidified at 800 °C and melted at higher temperatures. This proves that US olivine sand is not suitable to be used as a thermal energy storage and heat transfer medium in high-temperature particle-based CSP systems. The experimental results of thermal diffusivity/conductivity reveal that, for all particulates, both properties decrease with the increase in temperature, and results up to 475.5 °C are reported. Full article

The growing imperative to mitigate climate change and accelerate the shift toward energy sustainability has called for a critical evaluation of heat and electricity generation methods. This article presents a comparative life cycle assessment (LCA) of solar and biogas energy systems on a common basis of 1 kWh of useful energy using SimaPro, the ReCiPe 2016 methodology (both midpoint and endpoint indicators), and cumulative energy demand (CED) analysis. This study is the first to evaluate co-located solar PV, solar thermal compound parabolic concentrator (CPC) and biogas combined heat and power (CHP) systems with in situ data collected under identical climatic and operational conditions. The project costs yield levelized costs of electricity (LCOE) of INR 2.4/kWh for PV, 3.3/kWh for the solar thermal dish and 4.1/kWh for biogas. However, the collaborated findings indicate that neither solar-based systems nor biogas technology uniformly outperform the others; rather, their effectiveness hinges on contextual factors, including resource availability and local policy incentives. These insights will prove critical for policymakers, industry stakeholders, and local communities seeking to develop effective, context-sensitive strategies for sustainable energy deployment, emissions reduction, and robust resource management. Full article

Efficient water heating is essential for wool-washing processes, which demand temperatures above 70 °C. To meet this requirement sustainably, a parabolic trough solar concentrator system is proposed in this paper as an alternative to conventional natural gas systems. The design centers on a water pool constructed from bricks reinforced with an internal steel layer, enhancing heat exchange efficiency. Also, various synthetic oils were analyzed as heat transfer fluids (HTFs) within an immersed heat exchanger, such as Thermia B oil, Heat Transfer Oil 32, biphasic oil, and Therminol vp1 oil. Numerical simulations were performed using ANSYS CFX v19.2 software with the k-ε turbulence model to evaluate the thermal performance and temperature distribution. The results demonstrate the superior efficiency of the solar-powered system, with the steel-reinforced pool achieving optimal water temperatures between 78 °C and 85 °C, exceeding the required threshold for industrial wool washing. Among the various synthetic oils analyzed, Thermia B emerged as the most effective heat transfer fluid, maintaining water temperatures in the range of 75 °C to 85 °C. This superior thermal performance is attributed to its high thermal conductivity and reduced heat loss, ensuring consistent and optimal heat distribution for the wool-washing process. Full article

The MENA region, with its high solar potential and increasing investments in renewable energy, is transitioning away from fossil fuels toward more sustainable energy systems. To fully benefit from this transition and address issues such as intermittency and energy storage, “green” hydrogen is emerging as a key parameter. When produced using simple and cost-effective technologies like linear Fresnel reflector (LFR), it offers a practical solution. Therefore, assessing the potential of hydrogen production from LFR technology is essential to support the development of the energy sector and promote local industrial growth. This study investigates “green” hydrogen production using a 50 MW concentrated solar power (CSP) system based on LFR technology, where the CSP system generates electricity to power a proton exchange membrane electrolyzer for hydrogen production for three locations, including Ain Beni Mathar in Morocco, Assiout in Egypt, and Tabuk in Saudi Arabia. The results show that Tabuk achieved the highest annual hydrogen production (45.02 kg/kWe), followed by Assiout (38.72 kg/kWe) and Ain Beni Mathar (32.42 kg/kWe), with corresponding levelized costs of hydrogen (LCOH₂) of 6.47 USD/kg, 6.84 USD/kg, and 7.35 USD/kg, respectively. In addition, several sensitivity analyses were conducted addressing the impact of thermal energy storage (TES) on the hydrogen production and costs, the effect of reduced investment costs resulting from the local manufacturing of LFR components, and the futuristic assumption of the electrolyzer cost drop. The integration of TES enhanced hydrogen output and reduced LCOH₂ by up to 9%. Additionally, a future PEM electrolyzer costs projected for 2030 showed that LCOH₂ could decrease by up to 1.3 USD/kg depending on site conditions. These findings demonstrate that combining TES with cost optimization strategies can significantly improve both technical performance and economic feasibility in the MENA region. Full article

Concentrating photovoltaic-thermal (CPVT) collectors use reflective surfaces to focus sunlight onto a smaller receiver area, increasing thermal energy output while maintaining annual energy efficiency. Ray-tracing simulations are employed in this study using Tonatiuh to optimise the characteristics of the Double MaReCo (DM) collector, which is an improved version of the commercially available Solarus Power Collector (PC). Focused on enhancing electrical performance, the photovoltaic (PV) cell configurations are varied on the bottom side of the receiver, while the top-side PV cells remain constant. The study also analyses the influence of diodes and transparent gables on the annual solar irradiance received by the PV cells. From the analysis, it is observed that the specific annual irradiance received by the PV cells in the DM collector with transparent gables is nearly 64% more compared to that of the PC counterpart. It is also observed that the transparency of gables becomes significant only when the whole area of the receiver is covered by PV cells. With the goal of improving performance while lowering the cost and complexity of the DM collector, the study investigates various collector design characteristics that may shed more light on optimising the current model. Full article

Barium stannate (BaSnO₃) has emerged as a promising alternative electron transport material owing to its superior electron mobility, resistance to UV degradation, and energy bandgap tunability, yet BaSnO₃-based perovskite solar cells have not reached the efficiency levels of TiO₂-based designs. This theoretical study presents a design-driven evaluation of BaSnO₃-based perovskite solar cell architectures, incorporating MAPbI₃ or FAMAPbI₃ perovskite materials, Spiro-OMeTAD, or Cu₂O hole transport materials as well as hole-free configurations, under varying light intensity. Using a systematic device modelling approach, we explore the influence of key design variables—such as layer thickness, donor density, and interface defect concentration—of BaSnO₃ and operating temperature on the power conversion efficiency (PCE). Among the proposed designs, the FTO/BaSnO₃/FAMAPbI₃/Cu₂O/Au heterostructure exhibits an exceptionally effective arrangement with PCE of 38.2% under concentrated light (10,000 W/m², or 10 Sun). The structure also demonstrates strong thermal robustness up to 400 K, with a low temperature coefficient of −0.078% K⁻¹. These results underscore the importance of material and structural optimisation in PSC design and highlight the role of high-mobility, thermally stable inorganic transport layers—BaSnO₃ as the electron transport material (ETM) and Cu₂O as the hole transport material (HTM)—in enabling efficient and stable photovoltaic performance under high irradiance. The study contributes valuable insights into the rational design of high-performance PSCs for emerging solar technologies. Full article

Molten salt heat exchangers are pivotal components in advanced energy systems, where their high-temperature stability and efficient heat transfer performance are critical for system reliability. This paper provides a comprehensive review of recent advancements in molten salt heat exchanger technology, focusing on their application in nuclear energy, concentrated solar power, and thermal energy storage systems. Key design considerations, including thermophysical properties of molten salts and operational conditions, are analyzed to highlight performance optimization strategies. The review traces the evolution from traditional shell-and-tube heat exchangers to compact designs like printed circuit heat exchangers, emphasizing improvements in heat transfer efficiency and power density. Challenges such as material corrosion, manufacturing complexities, and flow dynamics are critically examined. Furthermore, future research directions are proposed, including the development of high-performance materials, advanced manufacturing techniques, and optimized geometries. This review aims to consolidate dispersed research findings, address technological bottlenecks, and provide a roadmap for the continued development of molten salt heat exchangers in high-temperature energy systems. Full article

Among the concentrating solar power (CSP) technologies, the parabolic trough (PT) solar collector is a proven technology mainly used to produce electricity and heat for industrial processes. Since 2003, a stand-alone Molten Salt Parabolic Trough (MSPT) experimental plant, located in the ENEA research centre of Casaccia (PCS plant), has been in operation. In this paper a brief description of the plant, the main plant operation figures, and a report of the main results obtained during the experimental test campaigns are presented. The aim of the tests was the evaluation of the thermal power collected as a function of DNI, mass flow rate, and inlet temperature of molten salt; experimental data were compared with simulation results obtained using a heat transfer software model of the solar receiver. Full article

Spain’s energy transition poses the dual challenge of managing renewable curtailment and enhancing the competitiveness of concentrated solar power (CSP) technologies. This study evaluates the suitability of replacing molten salts with solid particles for energy storage and, additionally, explores the storage of surplus electricity from grid in Carnot batteries. Four scenarios were analyzed using a Gemasolar-type plant model: each storage medium was studied with and without the integration of curtailed electricity. The solar field was modeled with SAM (System Advisor Model), while curtailment data from Red Eléctrica de España (2016–2021) quantified the available surplus. Results show that solid particles lead to 7.4% higher annual electricity production compared to molten salts, mainly due to improved power cycle efficiency. The integration of curtailment increased output further, with the solid particle Carnot battery scenario achieving the highest performance (up to 19.0% sun-to-electricity efficiency and 69.7% capacity factor). However, round-trip efficiency for curtailment storage was limited (~25–27%), and although solid particles showed lower LCOE (levelized cost of energy) than salts (192 vs. 211 USD/MWh), the Carnot battery increased costs. These findings suggest that while solid particles offer clear advantages, the economic viability of Carnot batteries remains constrained by current cost and operational limitations. Full article

Cooking food is a factor that contributes to global energy consumption and greenhouse gas emissions. This research proposes the design, simulation using thermal resistances with MATLAB Simulink, and experimental evaluation of an automated double-concentrated solar cooking system operable from inside a home. Water was used as a cooking load. Each test for 25 min was entered into a system integrated by a programmable elevator to transport the food to the roof, a configurable temperature display, a photovoltaic power source, and double solar collection (direct through a modified box oven and reflected by a parabolic dish collector). When both solar components operated simultaneously, the system reached a temperature of 79 °C, representing a 57.34 °C increase. On average, the solar concentrator provided 78.02% more energy than the oven alone. This approach is expected to reduce cooking time and contribute to sustainable home design aimed at mitigating greenhouse gas emissions. Full article

The aim of this study is to address the lack of comprehensive analysis methods for multi-functional Trombe wall systems. The objective is to establish an integrated evaluation system that assesses thermal, purification, and power generation performance. This study introduces a novel multi-objective analysis method coupling energy and exergy efficiency for three types of Trombe wall structures: traditional, thermal-catalytic (TC), and TC–photovoltaic (TC-PV). This study simultaneously monitors heat transfer, formaldehyde degradation, and photovoltaic power generation performance. A key novelty is the introduction of a quantitative index for “purification efficiency” and the revelation of the co-evolution law between PV (photovoltaic) coverage and the three types of efficiency for the first time. This study evaluates three cases: traditional, TC, and TC-PV Trombe walls. The results show that the thermal efficiencies of the three Trombe walls are 47.2%, 41.9%, and 51.7%, respectively, with corresponding thermal exergy efficiencies of 0.59%, 0.49%, and 0.63%. The TC and TC-PV Trombe walls achieve purification efficiencies of 57.0% and 53.0% and purification exergy efficiencies of 2.53% and 2.42%, respectively. The TC-PV Trombe wall has electrical and electrical exergy efficiencies of 16.0% and 12.84%, respectively. System structure optimization analysis indicates that the system achieves the best exergy efficiency when the solar irradiation is 400 W/m² and the air channel thickness is 0.05 m. Additionally, the purification exergy efficiency increases with higher formaldehyde concentrations, while thermal, purification, and electric exergy efficiencies all increase with greater PV coverage. Exergy loss analysis reveals that the TC layer and heat-absorbing plate are major sources of loss. Therefore, developing catalytic materials with high absorptivity and high catalytic activity could enhance the system’s exergy efficiency. Full article

Silica aerogels exhibit exceptionally low thermal conductivity and a low apparent density, as they are unique porous nanomaterials. They are extensively used in thermal insulation in terms of aerospace and building construction, adsorption processes for environmental applications, concentrating solar power systems, and so on. However, the degradation of the silica aerogel’s nanoporous structure at high temperatures seriously restricts their practical applications. Through a comprehensive review of the high-temperature structural evolution and sintering mechanisms of silica aerogels, this paper introduces two strategies to enhance their thermal stability, including heteroatom doping and surface heterogeneous structure construction. In particular, atomic layer deposition (ALD) of ultra-thin coatings on silica aerogel holds significant potential for enhancing thermal stability, while preserving its ultra-low thermal conductivity. Full article

Molecular solar thermal (MOST) energy systems can be utilized for the absorption, storage, and release of energy from the ultraviolet (UV) band of the solar spectrum. In this study, we designed a molecular solar thermal energy storage and release device based on the photoisomerization reaction of azobenzene. The device was integrated with a parabolic trough solar system, broadening the absorption range of the solar spectrum. By utilizing a coated secondary reflector, the system achieved efficient reflection of ultraviolet (UV) light in the 290–490 nm range, while solid-state azobenzene enabled the conversion of photon energy into chemical energy for storage and release. Experimental results under winter outdoor conditions demonstrated that: the secondary reflector significantly enhanced UV light concentration; the molecular solar thermal energy device exhibited remarkable thermal efficiency. Under an average solar irradiance of 302.23 W·m⁻², the device demonstrated excellent thermal performance, with the azobenzene reaching a peak temperature of 42.07 °C. The maximum heat release capacity was measured at 10.89 kJ·kg⁻¹·m⁻¹, while achieving a remarkable heat release power of 29.31 W·kg⁻¹·m⁻¹. Full article

Combining energy storage with base-load power sources offers an effective way to cover the fluctuation of renewable energy. This study proposes a nuclear–solar hybrid energy system (NSHES), which integrates a small modular thorium molten salt reactor (smTMSR), concentrating solar power (CSP), and thermal energy storage (TES). Two operation modes are designed and analyzed: constant nuclear power (mode 1) and adjusted nuclear power (mode 2). The nondominated sorting genetic algorithm II (NSGA-II) is applied to minimize both the deficiency of power supply probability (DPSP) and the levelized cost of energy (LCOE). The decision variables used are the solar multiple (SM) of CSP and the theoretical storage duration (TSD) of TES. The criteria importance through inter-criteria correlation (CRITIC) method and the technique for order preference by similarity to ideal solution (TOPSIS) are utilized to derive the optimal compromise solution. The electricity curtailment probability (ECP) is calculated, and the results show that mode 2 has a lower ECP compared with mode 1. Furthermore, the configuration with an installed capacity of nuclear and CSP (100:100) has the lowest LCOE and ECP when the DPSP is satisfied with certain conditions. Optimizing the NSHES offers an effective approach to mitigating the mismatch between energy supply and demand. Full article