Energy Applications Research Articles

Insights into predicting equilibrium conditions of clathrate hydrates of methane + water-soluble hydrate former

This study aims to improve the prediction of equilibrium conditions in methane hydrate systems by incorporating diverse water-soluble hydrate formers and applying advanced machine learning techniques. Methane hydrates, which naturally form under high pressure and low temperature, can be more efficiently formed or dissociated by altering thermodynamic conditions using these hydrate formers. Accurate prediction of these conditions is crucial for optimizing gas storage and energy applications. In this research, molecular descriptors and operational parameters, such as mole fraction and pressure, are used as input variables to predict equilibrium temperature. Machine learning methods, including Decision Trees (DT), Random Forests (RF), Support Vector Machines (SVM), and Multi-Layer Perceptron (MLP), were employed with a novel data-splitting approach based on hydrate formers rather than traditional sample-based methods. Among these models, the RF achieved the highest performance, with a coefficient of determination (R2) of 0.930, a root mean square error (RMSE) of 1.71, and an average absolute relative deviation (AARD) of 0.48%. Feature selection, preprocessing, and Shapley Additive Explanations (SHAP) provided valuable insights into the influence of specific variables on model predictions. Additionally, a supplementary examination, termed the reduced model, highlights the critical role of proper feature selection, with certain features regarded as less important yet essential for the functionality of distance-based models, particularly for models like SVM and MLP. This work advances methane hydrate research by offering a more accurate and interpretable framework for predicting hydrate equilibrium, addressing key gaps in previous studies, and extending its applicability to a broader range of systems. Moreover, the introduction of a former-based data-splitting method improves generalization across different hydrate formers, while the use of SHAP values for model interpretability offers deeper insights into the relationships between molecular descriptors and hydrate equilibrium conditions. This study paves the way for improved selection of hydrate formers in hydrate systems.

A PDMS-Al Triboelectric Nanogenerator Using Two-Pulse Laser to Enhance Effective Contact Area and Its Application

A triboelectric nanogenerator (TENG) is a kind of energy harvester which converts mechanical energy into electrical energy with electron transfer and transport between two different materials during cycling tribology. To increase the contact area between tribo-layers and enhance the output of TENGs, many studies prepare patterned micro/nanostructured tribo-layers using semiconductor processes like lithography and etching at high cost and with long processing times. Here, we propose a new method to quickly produce high-aspect-ratio (HAR) microneedles of polydimethylsiloxane (PDMS) for TENG triboelectric layers using a two-pulse laser-ablated polymethyl methacrylate mold and casting. It has the merit of employing low-cost CO2 laser microfabrication and polymer casting in a feasible way to produce efficient tribo-electric layers. Two-pulse laser ablation is an efficient method for fabricating HAR microstructures with increasing depth at a constant width and density compared to single-pulse ablation. It enhances the depth of microneedles at a constant width and successfully casts PDMS tribo-layers with microneedles that have an aspect ratio 1.88 times higher than those produced by the traditional single-pulse process. The microneedle-PDMS (MN-PDMS) layer is combined with Al sheets to form the MN-PDMS-Al TENG. Compared with the flat PDMS-Al TENG and single-pulse PDMS-Al TENG, the two-pulse TENG enhances open-circuit voltage (Voc) by 1.63 and 1.48 times, the short-circuit current (Isc) by 1.92 and 1.47 times, and the output power by 3.69 and 2.16 times, respectively. This two-pulse ablation method promotes the output performance of TENGs, which has the potential for applications in self-powered devices and sustainable energy.

Metallic wood-based phase change material with superior anisotropic thermal conductivity and energy storage capacity

In this study, metallic wood-based phase change material (MWM) with high performance anisotropic thermal conductivity and energy storage capacity was developed by impregnating wood with myristic acid, and subsequent introducing low melting point alloy (LMA) into the wood through a facile alternating high and low temperature heat treatment. The heat-driven LMA was rapidly squeezed into the cell lumens of the wood so as to effectively inhibit the leakage of the internal myristic acid during melting. Benefited with the well-aligned and hierarchical porous structure, the filled LMA formed a continuous heat transfer network along the highly oriented transport tissue of wood, which could greatly reduce the interfacial thermal resistance and promote heat transfer. Compared with untreated wood, the thermal conductivity of MWM in longitudinal and radial directions were improved by more than 67 % and 75 %, respectively. In addition, it exhibited superior energy storage capability, with the latent heat of 90.23 J/g and 86.42 J/g during melting and solidification. The thermal stability and anti-leakage performance were satisfied. The phase change temperatures, enthalpies and chemical structure of MWM remained unchanged after 100 thermal cycles, demonstrating outstanding cycling reliability. With excellent energy storage performance and favourable thermal conductivity, the prepared MWM shows a promising application in energy saving buildings and solid wood floors.

Green Engineering of Silicon and Titanium Dioxide Architectures and Realizing Downstream Applications

AbstractBiomineralization has long been a source of inspiration and frustration for researchers in a wide variety of disciplines from ecologists and dental practitioners to materials scientists. An amazing variety of organisms have the capacity to produce inorganic mineral complexes through biomineralization. In this context, different organisms use proteins, peptides, and polysaccharides as templates to control the nucleation, growth, and morphology of structures containing minerals and metals. Due to lack of clarity in the field, distinctions are provided between the various biomineralization processes as Type I, II, and III biomineralization. Synthetic biomineralization is an emerging field in which these processes are applied to unnatural substrates to create useful inorganic materials with applications in a variety of fields. A comprehensive overview of silica and titanium oxide biomineralization is given, covering the major achievements this sub‐field has attained since its emergence. The ground‐breaking discoveries are focused based on the templating agent used and the mechanisms that are proposed in the field are discussed. Synthetic biomineralization are led, which are more recently demonstrated to have feasible applications in energy, electronics, construction, and biotechnology. These possibilities are discussed alongside prospects based on the current trend of research in the field.

Plasma sprayed high-entropy alloy coatings with enhanced water splitting activity in alkaline environment

Developing highly efficient electrocatalysts for water splitting is an effective strategy to promote renewable and sustainable energy resources. Multimetal high-entropy alloys (HEAs) have generated considerable attention as promising catalysts because of their unique properties. Herein, the porous HEA coatings have been prepared via the plasma spraying method, which is expected to resolve the above issues. The catalysts can afford a promising catalytic performance through the distinct porous structure. This work results that the CoCrFeNiAlMo catalyst possesses a tiny overpotential (253mV at 50mAcm-2) with minimal Tafel slope (59.75mV dec-1). At the same time, the CoCrFeNiAlMo catalyst also exhibits a relatively small overpotential for hydrogen evolution reaction. As catalysts for overall water splitting, it delivers a cell voltage of 1.74V at 50mAcm-2 and a superior durable for 48h. This research provides an insight for using the multinary HEA coatings as electrocatalysts in energy applications.

High efficiency removal of Cs+ by Fe-Co framework PBAs from radioactive wastewater

The widespread application of nuclear energy has increased the risk of contamination by radionuclide 137Cs. Prussian blue analogues are considered to be excellent materials for the removal of 137Cs from wastewater due to their unique structure. In this work, Cs+ adsorbent for PBAs with Fe-Co framework, potassium iron hexacyanocobaltate (PBAFe), was synthesized by room temperature precipitation method. Systematic structural characterization and performance results of PBAFe showed that it has a specific surface area of 452.8 m2/g and an average pore size of 8.6nm, providing more active sites for Cs+. The adsorption of Cs+ on PBAFe exhibited fast reaction kinetics (within 10min) and high adsorption capacity (82.90mg/g), and the removal rate of Cs+ reached 98.57%. The efficient removal of Cs+ by PBAFe in various real water environments showed its excellent selectivity and potential for practical application. In addition, adsorption mechanism studies showed that the adsorption of Cs+ was achieved by ion exchange with K+ in the PBAFe lattice. PBAFe has the advantages of simple synthesis and good selectivity, and has potential application in the harmless treatment of Cs+ in radioactive wastewater.

Polymer photosupercapacitors: combined nanoarchitectonics with polymer solar cell and supercapacitor for emerging powerpacks in next-generation energy applications

Polymer photosupercapacitors: combined nanoarchitectonics with polymer solar cell and supercapacitor for emerging powerpacks in next-generation energy applications

PM flux-reversal machine for wind energy application

Currently, attempts are being made to harness wind energy by means of non-conventional electrical machines such as flux reversal machines (FRM). The main advantage of the FRM, when compared with existing synchronous generators (SG), is that all the active parts like PMs and armature windings are mounted on the stator part, whereas leaving the rotor has simple and robust. In this study, the three-phase 6/8-pole flux reversal generators (FRGs) are selected, sized, designed, and analyzed using finite element analysis (FEA). The working principle, choice of stator and rotor poles, and machine design dimensions evaluation (analytical sizing procedure), as well as relevant performance details are discussed in this paper. This study is used to analyze, a popular 6/8 pole, 0.8 kW, 50 Hz, and examine the suitability for the wind energy applications in terms of torque and power density, torque ripple, power factor, and cogging torque under 2D finite element analysis (FEA). The analysis provides an update on the current state-of-the-art and as well as future thrust areas of research necessary to bridge the gap on what is still desired for the practical application of FRMs for wind energy.

Lead-Free Halide Double Perovskites for Sustainable Environmental Applications

The development of renewable energy sources has become a crucial objective in today's world due to increasing environmental concerns and the depletion of fossil fuels. Solar energy has emerged as a promising alternative. In recent years, there has been a significant focus on perovskite solar cells due to their remarkable power conversion efficiencies and their ability to be produced in a cost-effective manner. These cells have attracted considerable attention from researchers and industry professionals alike. However, traditional perovskite materials often contain toxic lead, raising concerns about their environmental impact and long-term sustainability. This article highlights the environmental concerns associated with lead-based perovskite materials and explores the advantages, challenges, and potential of lead-free halide double perovskites as sustainable alternatives for achieving an enlightening and sustainable future in the field of photovoltaics. Lead-free halide perovskites have been an area of active research in the field of nanotechnology and material science due to their potential for various applications. We provide an overview of perovskite solar cells as a promising technology, discussing their material properties and device performance. Furthermore, we present a comparative analysis between lead-based and lead-free perovskites, emphasizing the challenges and future perspectives associated with the development and implementation of lead-free alternatives. Through this analysis, we aim to shed light on the potential of lead-free halide double perovskites and inspire further research in the quest for environmentally friendly materials for solar energy applications.

A Novel Three-Active-Switch Isolated Bridgeless Inverter for Renewable Energy Applications

A Novel Three-Active-Switch Isolated Bridgeless Inverter for Renewable Energy Applications

Assessment of photovoltaic system in existence of nanomaterial cooling flow

In this study, a photovoltaic (PV) system was enhanced through the combination of a cooling duct utilizing a nanofluid composed of water and Al₂O₃ nanoparticles, aimed at optimizing thermal regulation and improving electrical efficiency. A novel approach was introduced by systematically examining the effects of channel cross-sectional shapes and fin arrangements on heat dissipation. Using a single-phase simulation model, the thermal performance of the nanofluid was evaluated across various nanoparticle shapes, providing new insights into the relationship between geometry and nanofluid cooling efficacy. The results demonstrated that altering the cross-sectional shape generally reduced thermal performance, but strategic fin configurations significantly enhanced heat transfer. The optimal design, featuring eight shorter fins arranged around an eight-lobed pipe, resulted in a 4.3% improvement in thermal performance. Additionally, blade-shaped nanoparticles were identified as the most effective, enhancing heat absorption by 1.15% compared to pure water. This research presents the first combination of advanced nanofluid cooling with a detailed analysis of geometric factors (cross-section and fin design) in PV systems. The findings provide practical guidelines for improving heat management in PV cells, ultimately leading to increased electrical efficiency and an extended operational lifespan. These insights hold promising implications for the design of more efficient solar energy systems and could inform future thermal management solutions in renewable energy applications.

Numerical investigation of combustion characteristics of hydrogen-enriched low calorific value landfill gas for energy applications

Landfill gas is regarded as a promising renewable energy resource. However, Low calorific value landfill gases with less than 40 vol% CH4 are not well suited for energy applications and therefore disposed by flaring or direct emission to atmosphere causing environmental problems. In the present work, the potential of using hydrogen-enriched low calorific value landfill gas for energy applications has been explored through numerical investigation of combustion characteristics of different blends of fuels. The ignition delay of fuel mixtures decreased with the increase of hydrogen fraction (H2 enrichment from 0 to 50 vol%) at stoichiometric conditions. At high initial pressure conditions, ignition delay showed a weak relationship with the pressure. The laminar burning velocity increased with the increment of hydrogen fraction for the range of equivalence ratios considered (φ = 0.7 – 1.4) and also with the increase of initial temperature. However, the laminar burning velocity decreased significantly with the increasing initial pressure and hydrogen enrichment has insignificant effect at high initial pressures. The sensitivity analysis shows that the main elementary reactions inhibit the laminar burning velocity more with increasing initial pressure. The combustion performance of low calorific value landfill gas with 30 vol% CH4 enriched with 30 vol% hydrogen shows comparable performance to biogas with 60 vol% CH4 for a range of operating conditions. The numerical investigation results show that hydrogen-enriched low calorific value landfill gas could be used for thermal applications with the use of suitably designed combustion systems operating at low initial pressures and relatively high initial temperatures.

HEAT TRANSFER IMPROVEMENT FOR A FILLED-TYPE COMPOUND PARABOLIC SOLAR COLLECTOR WITH U-TUBE: ENERGETIC AND ECONOMIC ANALYSIS

In this study, the thermal and economic performance of a compound parabolic collector (CPC) with a U-tube was evaluated. Different filling fluids of the evacuated tube and different mass flowrates were evaluated. A detailed analysis of the energy performance of the collector components was conducted, along with an evaluation of its optical and economic aspects. The evaluated collector presented an optical efficiency of about 63.6%. Air achieved the highest evacuated tube temperature (160.6 ºC), followed by thermal oil (84.6 ºC) and water (61.3 ºC). The increase in HTF mass flowrate reduced both temperature gain and thermal efficiency. Thermal oil demonstrated superior thermal performance, achieving 32.5% higher efficiency than air and 30.0% higher than water. Results showed the thermal oil as the most cost-effective fluid, with a leveled cost of heat of 0.034 $/kWh and a simple payback period of 2.8 years. These findings demonstrate the potential of CPC systems for efficient thermal energy applications, with thermal oil emerging as the optimal filling fluid for both thermal and economic performance. Additionally, this study provides valuable practical insights for designing more efficient and sustainable CPC-based solutions for thermal energy applications.

Unveiling the role of sintering temperatures in the physical properties of Cu-Mg ferrite nanoparticles for photocatalytic application

This research presents an explicit analysis of the effects of sintering temperature (Ts) on the structural, morphological, magnetic, and optical properties of Cu0.5Mg0.5Fe2O4 nanoferrites synthesized via the sol-gel method. To accomplish it, Cu-Mg ferrite NPs were sintered at temperatures ranging from 300 to 800 °C in increments of 100 with a constant holding duration of 5 h. Thermogravimetric analysis was used to observe the degradation of organic components and the thermally stable zone of the material. XRD analysis and SAED patterns revealed the formation of a single face-centred cubic (fcc) spinel structure with an Fd–3m space group. The particle's crystallite sizes have grown from 4.54 to 102.54 nm as Ts have increased, consistent with TEM results. Further evidence for the creation of spinel structure was provided by two prominent absorption bands in FTIR spectroscopy below 1000 cm−1. The particles were found to have a densely packed, nearly spherical morphology, as confirmed by TEM images. The EDS was utilized to identify the chemical species that were present in the sample. A significant correlation was observed between particle size and magnetic properties. The field-dependent magnetization investigations revealed that particles with crystallite sizes of 4.54 and 5.10 nm were superparamagnetic, while those measuring 11.68, 23.81, 42.95, and 102.54 nm exhibited ferrimagnetic characteristics. Furthermore, it was revealed that an increase in sintering temperature results in a concurrent amplification of crystallites, which subsequently heightens the saturation magnetization of the prepared NPs from 9.49 to 33.04 emu/g. The coercivity value clarifies the sintering effect of transforming the particle from a single-domain to a multi-domain magnetic state. The finite-size scaling formula precisely characterizes the changes in Curie temperature. In addition, the semiconducting characteristics of Cu-Mg ferrite NPs were confirmed through DRS, which unfolded an optical band gap within the range of 1.84–2.26 eV. The Mulliken electronegativity approach unveiled the prospective efficacy of these NPs in photocatalytically generating O2 from water. Cu-Mg nanoferrites exhibit a favourable bandgap and potential as a photocatalyst, rendering them a potentially fruitful addition to the family of ferrite materials utilized in photocatalytic and associated solar energy applications.

Valorization of Sargassum spp. biomass as a promising source of electrocatalysts for energy generation based on life cycle assessment

This work presents the development of an S-doped biocarbon electrocatalyst, designed to address environmental and economic challenges posed by the proliferation of Sargassum spp. along the shores of Quintana Roo, Mexico. The synthesis involves a two-step process: hydrothermal treatment followed by pyrolysis at 900°C. This method produces a material with an exceptional surface area of 2142 m2g⁻1 and a high content of thiophene-type bonds (94.30%). The unique composition of S-doped biocarbon results in superior catalytic activity for the oxygen reduction reaction, evidenced by an onset potential of 0.981 V vs Reversible Hydrogen Electrode (RHE) and a half-wave potential of 0.878 V vs RHE. Additionally, the electrocatalyst demonstrates remarkable electrochemical stability, maintaining performance with negligible mass activity loss after 5000 cycles. A significant application of S-doped biocarbon is demonstrated in a self-breathing Anion Exchange Membrane Fuel Cell (AEMFCs), achieving 76.82% of the power density output compared to a commercial Pt electrocatalyst cathode. Furthermore, a life cycle assessment reveals that the synthesis of 1 g of S-doped biocarbon emits only 1.27 kg CO₂-eq, which is 3.84% of the emissions attributed to Pt. Thus, S-doped biocarbon is an environmentally friendly biocarbon and a high-performing electrocatalyst for AEMFCs, positioning it as a promising alternative to Pt for green energy applications.

Probing the opto-electronic, thermoelectric, thermodynamic and elastic responses of lead-free double perovskite Li2ATlCl6 (A = Na and K) for potential photovoltaic and high- energy applications: A DFT study

The physical properties of double halide perovskite Li2ATlCl6 (A = Na and K) were examined through a first-principles study and semi-classical Boltzmann theory using the WEIN2k package, focusing on renewable energy generation and solar cell applications. Research on halides is growing within the optoelectronics and thermoelectric field and is anticipated to meet energy shortage demands. The volume-energy diagram confirms their structural stability, while the Pugh and Poisson ratios suggest ductility based on their elastic properties. The electronic properties were analyzed, and bandgaps were calculated using modified Becke-Johnson (mBJ) potentials, yielding bandgaps of 3.51 eV and 2.97 eV for Li2ATlCl6 (A = Na and K) respectively. The optical properties, evaluated using complex dielectric functions, indicated optimal light absorption in the infrared (IR) regions. Additionally, the thermoelectric (TE) properties of Li2ATlCl6 (A = Na and K) were analyzed using semi classical Boltzmann theory with a constant relaxation time approximation. At 1200 K, the calculated figures of merit (ZT) values were 0.75 and 0.69, respectively, indicating their potential for thermoelectric applications. Also, the thermodynamic properties are computed under pressure (0–15 GPa) and temperature (0–1200 K). These investigations offer a profound comprehension of these materials for their further employment. These results highlight their potential for optoelectronic device applications and are expected to encourage further experimental research on the feasibility of Li2ATlCl6 (A = Na and K) for optical devices.

Day-ahead photovoltaic power generation forecasting with the HWGC-WPD-LSTM hybrid model assisted by wavelet packet decomposition and improved similar day method

Precisely forecasting output of solar photovoltaics is crucial for (i) effective solar power management, (ii) integration into the electrical grid, (iii) flexible allocation of power resources. While deep learning algorithms have shown promise in energy applications, single algorithms often struggle with unstable predictions and limited generalizability for predicting photovoltaic (PV) output. This study introduces an innovative hybrid model (HWGC-WPD-LSTM) that integrates an improved similar day algorithm (WGC: weighted grey correlation analysis and cosine similarity), Wavelet Packet Decomposition (WPD), and Long Short-Term Memory neural network (LSTM) for predicting day-ahead power output. The model suggests an approach to identifying similar days by integrating weighted GRA with cosine similarity. It then decomposes power sequences employing WPD to capture various frequency characteristics. Four independent LSTM networks are then applied to these sub-sequences to forecast output, which are then reconstructed to derive the ultimate forecast outcome for solar photovoltaics. The evaluation of the hybrid model is conducted based on data gathered from actual generating station in Shandong Province, China. Then it is compared against other models utilizing similar day selection methods and other hybrid HWGC-BP, HWGC-Elman, HWGC-SVM, HWGC-RF, and HWGC-LSTM models. This comparison is based on four performance metrics: Mean Absolute Error (MAE), Root Mean Square Error (RMSE), normalized Root Mean Square Error (NRMSE), and Mean Absolute Deviation (MAD). Results demonstrate that the HWGC-WPD-LSTM model offers enhanced precision and stability (MAE = 0.2168 MW, RMSE = 0.2996 MW, NRMSE = 6.78 %, MAD = 2.18 %) in day-ahead power generation predictions. This highlights the potency of the hybrid model in enhancing the forecasting capabilities for solar photovoltaics, which is crucial for the strategic enhancement of renewable energy resource exploitation in the context of modern power systems.

Cryo-EM structure of a photosystem I variant containing an unusual plastoquinone derivative in its electron transfer chain.

Photosystem I (PS I) is a light-driven oxidoreductase responsible for converting photons into chemical bond energy. Its application for renewable energy was revolutionized by the creation of the MenB deletion (ΔmenB) variant in the cyanobacterium Synechocystis sp. PCC 6803, in which phylloquinone is replaced by plastoquinone-9 with a low binding affinity. This permits its exchange with exogenous quinones covalently coupled to dihydrogen catalysts that bind with high affinity, thereby converting PS I into a stable solar fuel catalyst. Here, we reveal the 2.03-Å-resolution cryo-EM structure of a recent MenB variant of PS I. The quinones and their binding environment are analyzed in the context of previous biophysical data, thereby enabling a protocol to solve future PS I hybrids and constructs from this genetically tractable cyanobacterium.

Triboelectric nanogenerator for high-entropy energy, self-powered sensors, and popular education.

Triboelectric nanogenerator (TENG) has become a promising option for high-entropy energy harvesting and self-powered sensors because of their ability to combine the effects of contact electrification and electrostatic induction to effectively convert mechanical energy into electric power or signals. Here, the theoretical origin of TENG, strategies for high-performance TENG, and its applications in high-entropy energy, self-powered sensors, and blue energy are comprehensively introduced on the basis of the fundamental science and principle of TENG. Besides, a series of work in popular science education for TENG that includes numerous scientific and technological products from our science education base, Maxwell Science+, is emphatically introduced. This topic provides an angle and notable insights into the development of TENG.

An emerging aspirant for solar cell and non-conventional energy applications: Lead free fluoro-perovskites A2TlInF6 (A = K, Rb)

In the present work; structural, electronic, optical, and thermoelectric properties of double perovskites A2TlInF6 (A = K, Rb) have been studied using the ab-initio method in conjunction with full potential Linear Augmented Plane Wave (FP-LAPW) method and PBE-GGA potential. Structural properties, cohesive energy, and formation enthalpy collectively confirmed the stability of the halide perovskites in a cubic structure with Fm3m symmetry. Electronic properties revealed the p-type semiconductor nature of both materials. The indirect band gap values for K2TlInF6 and Rb2TlInF6 were found to be 3.489 eV and 3.591 eV, respectively, with PBE. With PBE + SOC, the values dropped to 3.445 eV and 3.546 eV, respectively. Optical properties such as Dielectric function εω, Refractive Index nω, Extinction Coefficient κω, Optical Conductivity σ(ω), Reflectivity R(ω), Electron Energy Loss Function L(ω), and Absorption Coefficient αω were determined using PBE-GGA potential. BoltzTraP code was used to determine thermoelectric properties, namely, Seebeck Coefficient (S), Electrical Conductivity (σ), Thermal Conductivity (K), Power Factor (PF), and Figure of merit (ZT) which were studied in detail. The study suggests halide-based double perovskites may have the potential for solar energy utilization due to their high absorption coefficient, large values of refractive index, and optimal values of the figure of merit.