Energy Generation Devices Research Articles

Advances in Physics and Chemistry of Transition Metal Dichalcogenide Janus Monolayers: Properties, Applications, and Future Prospects

AbstractJanus transition metal dichalcogenides (JTMDs) have garnered significant interest from the scientific community owing to their remarkable physical and chemical features. The existence of intrinsic dipoles makes them different from conventional transition metal dichalcogenides. These properties are useful in various potential applications, including energy storage, energy generation, and other electronic devices. The JTMDs are considered a hot topic in two dimensional (2D) materials research, making it necessary to understand their fundamental properties and potential use in various applications. This review covers the fundamental difference between Janus and conventional transition metal dichalcogenide‐based 2D materials. This discussion encompasses the characteristics of monolayer, bilayer, and multilayer materials, focusing on their structural stability, electronics properties, optical properties, piezoelectricity, and Rashba effects. The impact of external stimuli such as strain and electric field toward engineering the ground state properties of monolayer JTMDs is discussed. Additionally, various potential applications of Janus monolayers, including gas sensors, catalysis, electrochemical energy storage, thermoelectric, solar cells, and field effect transistors, are highlighted, emphasizing enhancing their performance. Finally, the prospects of Janus 2D materials for next‐generation electronic devices are highlighted.

Design and Research of Dual-Mode Power Generation Device Based on Improved Oscillating Buoy

In response to the national “dual-carbon” strategic goals, a dual-mode ocean energy generation device was researched. First, improvements were made to the power generation system and mechanical structure of an oscillating buoy with a radius of 2.5 m, designing a power generation device that utilizes both wave energy and tidal energy. Subsequently, wave generation was carried out using the Realizable k-ε turbulence model, and the buoy’s strength was analyzed using the Ansys Fluent simulation platform with finite element analysis, with simulation results indicating a rational design. Then, the Froude–Krylov hypothesis method and the oscillating buoy body decomposition method were used to calculate the combined force in the vertical direction of the buoy, and combined with other forces, the maximum wave force on the buoy was determined. It was verified that the buoyancy of the buoy met the requirements of the hydraulic system. Finally, the hydraulic power generation system model was simulated and analyzed using AMEsim, yielding a power generation of 55.2284 kW. Using a formula, the maximum power generation of a single buoy was calculated to be approximately 15.5 kW, and the ideal maximum power generation of the entire device was able to reach 101.7284 kW.

Highly porous activated carbon derived from plant raw material as high-performance anode for aqueous sodium-ion supercapacitors

High power sodium energy generation devices, such as symmetric and hybrid supercapacitors, have great potential for cheap and green post-lithium applications. However, it is imperative to obtain porous structures with large surfaces and optimized pore size to enhance the electrode sorption property and to ensure fast electrochemical reactions. In this work, we investigated the influence of KOH carbon activation conditions on the morphology, porosity, and electrochemical parameters in aqueous sodium electrolytes. Our activated carbon had a maximum surface area of 1556 m2/g and a notably high mesopore content, this varying from 5 to 19 % of the total pore area. Electrochemical parameters are not only influenced by the total number of pores, but also by the optimal ratio of meso and micro pores. It is shown that in the case of sodium-based electrolytes, mesopores provide good electrode-electrolyte contact, and the capacity is mainly provided by micropores. High operating values of activated carbon in sodium aqueous electrolytes (specific capacity about 78 F/g, energy density 11 W*h/kg and power density 470 W/kg) indicates that the optimal electrode materials for a high-power device are activated carbon with a high content of mesopores obtained by the ratio of C and KOH as 1:4.

Advancing Ion Separation: Covalent-Organic-Framework Membranes for Sustainable Energy and Water Applications.

ConspectusMembranes are pivotal in a myriad of energy production processes and modern separation techniques. They are essential in devices for energy generation, facilities for extracting energy elements, and plants for wastewater treatment, each of which hinges on effective ion separation. While biological ion channels show exceptional permeability and selectivity, designing synthetic membranes with defined pore architecture and chemistry on the (sub)nanometer scale has been challenging. Consequently, a typical trade-off emerges: highly permeable membranes often sacrifice selectivity and vice versa. To tackle this dilemma, a comprehensive understanding and modeling of synthetic membranes across various scales is imperative. This lays the foundation for establishing design criteria for advanced membrane materials. Key attributes for such materials encompass appropriately sized pores, a narrow pore size distribution, and finely tuned interactions between desired permeants and the membrane. The advent of covalent-organic-framework (COF) membranes offers promising solutions to the challenges faced by conventional membranes in selective ion separation within the water-energy nexus. COFs are molecular Legos, facilitating the precise integration of small organic structs into extended, porous, crystalline architectures through covalent linkage. This unique molecular architecture allows for precise control over pore sizes, shapes, and distributions within the membrane. Additionally, COFs offer the flexibility to modify their pore spaces with distinct functionalities. This adaptability not only enhances their permeability but also facilitates tailored interactions with specific ions. As a result, COF membranes are positioned as prime candidates to achieve both superior permeability and selectivity in ion separation processes.In this Account, we delineate our endeavors aimed at leveraging the distinctive attributes of COFs to augment ion separation processes, tackling fundamental inquiries while identifying avenues for further exploration. Our strategies for fabricating COF membranes with enhanced ion selectivity encompass the following: (1) crafting (sub)nanoscale ion channels to enhance permselectivity, thereby amplifying energy production; (2) implementing a multivariate (MTV) synthesis method to control charge density within nanochannels, optimizing ion transport efficiency; (3) modifying the pore environment within confined mass transfer channels to establish distinct pathways for ion transport. For each strategy, we expound on its chemical foundations and offer illustrative examples that underscore fundamental principles. Our efforts have culminated in the creation of groundbreaking membrane materials that surpass traditional counterparts, propelling advancements in sustainable energy conversion, waste heat utilization, energy element extraction, and pollutant removal. These innovations are poised to redefine energy systems and industrial wastewater management practices. In conclusion, we outline future research directions and highlight key challenges that need addressing to enhance the ion/molecular recognition capabilities and practical applications of COF membranes. Looking forward, we anticipate ongoing advancements in functionalization and fabrication techniques, leading to enhanced selectivity and permeability, ultimately rivaling the capabilities of biological membranes.

Design of a Wave Generation System Using an Oscillating Paddle-Type Device Anchored to Fixed Structures on the Coast

Wave energy, a form of renewable energy, is derived from the movement of sea waves. Wave energy generation devices are technologies designed to harness this resource and convert it into electricity. These devices are classified based on their location, size, wave direction, and operating principle. This work presents the design of an oscillating device for harnessing wave energy. For this purpose, computational fluid dynamics and response surface methodology were employed to evaluate the influence of the percentage of the blade height submerged below the water surface (X1) and the distance from the device to the breakwater in terms of the percentage of the wave length (X2). The response variable studied was the hydrodynamic efficiency (η) of the device. Transient fluid dynamic simulations were carried out using Ansys Fluent software 2023 R1, with input conditions based on a wave spectrum characteristic of the Colombian Pacific Ocean. Analysis of variance determined that both factors and their interaction have significant effects on the response variable. Using the obtained regression model, the optimal point of the system was determined. Numerical results showed that the maximum η of the system was achieved when the device was submerged at 75% of its height and was positioned 10% of the wave length away from the vertical breakwater. Under this configuration, η was 64.8%. Experimental validations of the optimal configuration were conducted in a wave channel, resulting in a η of 45%. The difference in efficiencies can be attributed to mechanical losses in the power take-off system, which were not considered during the numerical simulations.

Numerical investigation of the hydrodynamic properties of oscillating water column air chambers

Abstract The oceans occupy nearly 71% of the Earth’s surface area. The ocean is rich in energy, and wave energy is one of its important components. Therefore, the study of wave energy generation devices is an important issue. In this paper, we analyze the effect of the size of the air chamber structure on the OWC (oscillating water column) wave energy conversion device under the action of unidirectional regular waves. To analyze the performance of the OWC device under real sea conditions, the wave climate at Sanmenxia is used as the experimental parameter. The performance and characteristic response with the variation of incident wave height, air chamber width and front wall thickness, are analyzed. The results show that the incident wave height, air chamber width, and front wall draft have significant effects on the performance of OWC. With the increase of incident wave height, the wave nonlinear effect increases. As the air chamber width decreases, the horizontal surface inside the air chamber undulates smoothly and the standing wave phenomenon disappears.

Polymer Nanocomposites with UiO-Derived Zirconia Fillers for Energy Generation and Pressure-Sensing Devices: The Role of Crystal Structure and Surface Characteristics

Polymer Nanocomposites with UiO-Derived Zirconia Fillers for Energy Generation and Pressure-Sensing Devices: The Role of Crystal Structure and Surface Characteristics

Optimization of Buoy Shape for Wave Energy Converter Based on Particle Swarm Algorithm

In order to improve the wave energy capture rate of the buoy of a wave energy generation device, this paper proposes a multi-degree of freedom method to optimize the shape of the buoy with maximum wave energy capture. Firstly, a multi-degree of freedom wave energy converter was designed, and the buoy shape was defined using a B-spline curve to generate the shape vector; then, a numerical model of the multi-degree of freedom wave energy converter was established and numerical calculations were carried out using AQWA/WEC-Sim software; on this basis, the particle swarm optimization algorithm was introduced to find the buoy shape corresponding to the maximum wave energy capture. Finally, the optimization of the buoy shape was in irregular waves. The results show that as the wave energy capture increased, the buoy shape tended to be flatter, with a smaller taper, and the optimal buoy shape had a better motion response than the conventional cone buoy. Eventually, the correctness of the buoy shape optimization method was verified through experimental testing.

Biocarbon-Enhanced Flexible Nanofiber Mats for Sustainable Energy Generation and Wearable Device Applications

A broad diversity of nanofillers and polymers have been used to prepare polymer nanocomposites having potential applications in transportation, sports materials, aerospace, electronics, communication, energy, environment, and biomedical. Polyvinylidene fluoride (PVDF) finds a remarkable place in energy applications attributed to its highest known piezo- and pyroelectric properties. Like most carbon materials, Biochar has excellent electrical conductivity, since it comprises graphene layers with a great amount of carbon content. This study explores the behavior of composite nanofibers fabricated from rice straw-derived biochar-PVDF as wearable mats to harvest body energy into electricity. The composite nanofiber mats were fabricated using the electrospinning technique to get the benefit of both the piezoelectric properties of PVDF and the excellent electric properties of Biochar. The research found that incorporating 12 wt % of Biochar greatly enhances the piezoelectric content of the nanofiber mats without noteworthy loss in flexibility. In addition, the effects of membrane thickness (0.5, 0.9, and 1 mm) on their output voltages as a performance factor of the nanogenerator were measured. Results indicated that the effect of thickness was most influential in the thickness of 1 mm of PVDF/biochar nanofibers generator. The results of this work imply promising application development of such flexible composite piezoelectric nanofibrous membranes for environmentally sustainable energy generation and wearable self-powered electrical devices.

Electrical, optical, and electrochemical performances of phosphate-glasses-doped with ZnO and CuO and their composite with polyaniline

Phosphate-based glasses (PBG) with appropriate doping agents have been used as solid electrolytes in solid-state ionic devices. Therefore, more light was shed on the electrical, optical, and electrochemical behavior of the phosphate-based glasses (PBG), containing ZnO or CuO in the absence and existence of conductive polyaniline (PANI), since no publications are available concerning this work. The glass samples were prepared by the rapid quenching method, then mixing phosphate glass and polyaniline (PANI) with metal oxide (ZnO, CuO). They were characterized by different techniques; diffuse reflectance spectrophotometer (DRS), broadband dielectric spectrometer (BDS), cyclic voltammetry (CV), and charge–discharge techniques. In the DRS study, the direct and indirect band gap were calculated from Tauc’s relationship where CuO-doped glasses have higher values than ZnO-doped glasses. In the BDS study, the permittivity of all glass compositions decreased while AC conductivity increased with increasing frequency. AC conductivity of PBG doped with metal oxides and mixed with PANI exhibited semiconducting features (6.8 × 10–4 S/cm). Further, these composites exhibited lower loss tangent (0.11), and giant permittivity (186,000) compared to the pure PBG. Also, the electrochemical study exhibited that the composite with 7% CuO content has the highest specific capacitance value (82.3 F/g at 1.0 A/g) which increased to about 113% of its first cycle and then decreased to about 55% after 2500 cycles and finally increased again to 77% after 4500 cycles, indicating its good stability. The combination of optical, electrical, and electrochemical features of these composites suggests their use for energy generation and storage devices.

Cost-efficiency based residential power scheduling considering distributed generation and energy storage

The permeation of renewable energy into smart house is a key characteristic of the future power system that brings a significant challenge to the peak load management in the power sector. In this paper, we propose cost-efficiency based residential power scheduling scheme considering distributed generation and energy storage. In which, a cost-efficiency model designed by the ratio of consumption benefit to its cost is introduced to capture the residential users' electricity consumption behaviors and reflect their economic efficiency. A discomfort cost is constructed to represent the losses associated with power scheduling when facing the incentives given by the smart grid. Specially, not only residential load consumption utility, but also that of the renewable energy generation and energy storage devices are applied to compose the consumption benefit，and an energy storage model to be established to plan the charging and discharging of energy storage batteries. Day-Ahead Bidding Price and Real-time consumption management models are introduced to test the performance of the proposed scheduling scheme. Simulation results demonstrate that the proposed method increases the residential consumer's daily cost efficiency by 1.5834, and reduces its daily electricity bill by 38.43 % and that about 36.86 % of energy is saved in the smart grid while the proposed scheduling strategy for energy consumption can effectively smooth the load curve in smart grid.

Solar spectral management in space using lanthanide-based downshifting layers

Photovoltaic (PV) cells are still the most used energy generation devices for aerospace applications. Although multijunction solar cells represent the standard commercial technology for powering spacecraft, spacecraft companies are still using Si-based PV cells to decrease the cost of satellites at the expense of efficiency and energy generation losses. One of the limitations on solar energy conversion is the mismatch between the solar spectrum and the absorption of the PV technology in use. Thus, strategies to overcome this have been proposed, namely the use of luminescent downshifting layers (DSLs) which are very promising to shape the incident sunlight. In this sense, downshifting materials with absorption in the UV/blue spectral region have been privileged considering the solar spectrum in space environments (AM0 solar spectrum), in which the UV component is larger than that on Earth surface (AM1.5 solar spectrum). Here, we propose the use of Eu3+-doped di-ureasil organic-inorganic hybrid materials as DSLs to be used on large area Si-based PV cells (∼0.1 m2) for space applications. Electrical measurements on the PV cell, done before and after the deposition of the DSLs, confirm the positive effect of the coatings on the device performance, with a relative increase on the generated electrical power of ∼2.6 %. Here, we report, for the first time, a DSL specifically designed for space applications and with the largest active area reported so far.

Challenges, limitations, and applications of nanofluids in solar thermal collectors-a comprehensive review.

The daily increase in the demand for energy consumption is partly caused by the global population explosion and advancements in technology. Humanity relies on energy to fulfil its daily routines, such as electricity for lighting, heating, cooling, and running electronic devices. There are continuous attempts by researchers and industry experts to optimize and enhance the efficiency of various sustainable energy generation devices. Solar collectors play a critical role in the renewable energy sector, which is vital in helping the world achieve a clean, green, and sustainable environment. Over the last two decades, researchers have made significant efforts to explore various techniques for enhancing the effectiveness of solar thermal collectors. Their effort has been centered around improving the fluid thermal properties, which act as the heat transfer medium in solar collectors. The discovery of nanofluids will help resolve some of the challenges associated with conventional fluid used in solar collectors. Enhancement through nanofluids is influenced by several factors, which include nanoparticle types, nanoparticle concentration, base fluid, and the purpose of its application. This review provides a technical summary of the application of nanofluids in the two main types of collectors: non-concentrating and concentrated thermal collectors. Findings from this study showed that TiO2 + Cu hybrid nanofluids with a mass fraction of 0.03 augment heat transfer coefficient by 21% in parabolic trough collectors. The merits of employing nanofluids as heat transfer fluids in solar collectors are examined, while also outlining the obstacles and areas where further research is needed.

Graphene wettability: Fundamentals, modulations, and applications in energy fields

Over the last decade, there has been a remarkable surge in the development of graphene-based energy generation, storage, transduction, and harvesting devices, driven by the exceptional electronic, optical, thermal, chemical, and mechanical properties of graphene. Notably, the tunable wettability of graphene offers an intriguing opportunity to enhance the performance of energy systems that utilize or involve water during device fabrication and usage stages, such as solar cells, nanogenerators, and supercapacitors. In this review, we provide an extensive overview of the latest research progress in the intrinsic wettability of graphene and its influencing factors, including substrate, contamination, defects, doping, and layer number. Subsequently, we highlight the representative applications in water-involved energy fields of high-quality graphene films synthesized via chemical vapor deposition. Lastly, we discuss current challenges in adopting graphene in the energy fields and propose future directions to promote the adoption of graphene in water-involved energy devices. Overall, this review presents critical insights into the significance of graphene wettability in advancing both the fundamental research and practical applications of graphene in energy fields.

Improving water removal efficiency in a PEM fuel cell: Microstructured surfaces for controlling instability-driven pinching

Proton Exchange Membrane Fuel Cell (PEMFC) is a clean, sustainable energy generation device, and its large-scale usage is becoming popular due to green and secure energy demand worldwide. The performance, efficiency, and lifespan of PEMFC largely depend on the water removal and management within the cell. Under the influence of the cross-air flow, the generated water filaments deform, and as the filament radius lowers, the curvature and capillary pressure increase, ejecting fluid out of the neck at increasing velocities. The moment the filament radius vanishes, the governing equations reach the point of singularity, and the filament breaks. We propose an optimum micro-patterned surface design for efficient water removal from PEMFC. We perform a numerical study of water generation on the surface followed by breakup under shear flow within confinement. We further theoretically identify the breakup behavior with characterization, recognizing the influence of the microstructures toward an efficient design. The hydrophobic microstructures are observed to decrease the dominance of viscous force over inertia and capillary force. This leads to a greater propensity of end-pinching or truncation of the generated droplet at the neck, which reduces the production of undesired satellite droplets that would have otherwise caused flooding of the chamber. In this work, we show that a proper combination of substrate structure and jet velocity-induced shear can mitigate the generation of satellite droplets and reduce the breakup time, significantly increasing the water removal efficiency of the PEMFC.

Real-time pricing based on convex hull method for smart grid with multiple generating units

With the growing demand and complex supply structure for electricity, higher requirements are proposed for generating units to regulate the peak load, resulting in significant increases in the startup cost. These issues bring urgent need to develop new pricing mechanisms. The real-time pricing (RTP) is an ideal pricing mechanism for clipping peak load and balancing supply and demand. This paper designs an RTP mechanism for the smart grid which integrates multiple generating units on the supply side and distributed renewable energy generation devices and energy storage systems on the demand side. Focusing on the interests of both supply and demand sides, a social welfare maximization model that incorporates startup costs of generating units is formulated. To tackle the discontinuity in the proposed model, the convex hull method is utilized to transform the primal model and derive the convex hull price which is widely regarded as an optimal price that can reflect the aggregate cost of generating units but has rarely extended to RTP. The related dual theory indicates that the convex hull price can be obtained by the Lagrange multiplier of the proposed social welfare maximization problem associated with the supply–demand balance constraint. Moreover, a distributed iterative algorithm based on the subgradient projection method is employed to solve the dual problem. Simulation results validate rationality and effectiveness of the proposed pricing mechanism.

Research on the modeling and control mechanism of three-phase cascade rectification stage of non-power frequency transformer

Non-power frequency transformers are essential and important devices for new energy generation and smart grid construction. This article analyzes the working principle of voltage cascade rectifier stage, constructs a mathematical model of three-phase cascade rectifier stage system, and simplifies its model. Finally, the idea of overall control of the voltage loop in the rectifier stage system was derived, and the traditional control method of rectification was directly transplanted into the overall control system of the cascade rectifier stage. At the same time, the characteristics of voltage loop and current loop of cascade rectifier stage system are analyzed, and the relevant control structure block diagram and controller design idea are given, which lays an important theoretical foundation for in-depth study of non-power frequency transformer.

Silicon infused Molybedenum di-selinide (MoSe2) nanosheets for enhanced hydrogen evolution reaction (HER) and lithium-ion battery (LIB) applications

The systematized design of two-dimensional (2D) nanocatalysts for sensible energy-efficient reactions is quite a puzzling prospective aspect in energy-related applications. In this current work, we used a top-down strategy to synthesize silicon (Si) nanoparticles using a high-energy mechanical ball milling technique. In hydrothermal reaction, these Si nanoparticles were introduced into the 2D MoSe2 matrix sequence based on varying the percentages of silicon (0–15%) vs Selinium content. The high crystalline phases of the synthesized 10% Si:MoSe2 exhibited the sheet-like morphology and silicon inserted layered structure. The pristine MoSe2@CC & Si:MoSe2@CC electrodes were prepared by tape casting method. During HER reaction, the miniscule insertion of Si into MoSe2 matrix amplified the current density until 10% addition and moved the reduction curves towards lower onset overpotential (76.23 mV) in addition to the significant Tafel value (112.3 mV/decade). The potential of the better performed electrode in HER was explored as an anode for Lithium-ion battery (LIB) applications. The electrode delivered a discharge capacity of 406.7 mAh g−1 at a current density of 100 mA/g after 100 charge-discharge cycles. Furthermore, the rationally constructed bifunctional electrode (Si:MoSe2@CC) showed strong physicochemical stability, which can be used in future sustainable energy generation and storage devices.

High Hydrovoltaic Power Density Achieved by Universal Evaporating Potential Devices.

While hydrovoltaic electrical energy generation developments in very recent years have provided an alternative strategy to generate electricity from the direct interaction of materials with water, the two main issues still need to be addressed: achieving satisfactoryoutput power density and understanding the reliable mechanism. In the present work, the integration of capacitors and water evaporation devices is proposed to provide a stable power supply. The feasible device structure consuming only water and air is green and environmentally sustainable, achieving a recorded power density of 142.72µWcm-2 . The output power of the series of devices is sufficient to drive portable electronic products with different voltage and current requirements, enabling self-driving systems for portable appliances. It has been shown that the working behavior originates from evaporating potential other than streaming potential. The present work provides both theoretical support and an experimental design for realizing practical application of hydrovoltaic electrical energy generation devices.

Optimization of the chamber of OWC to improve hydrodynamic performance

Nearly 71% of Earth's surface area is occupied by the ocean, which is abundant in energy, with wave energy being one of its essential components. As a result, the investigation of wave energy generation devices is a crucial matter. This paper analyzes the performance of the oscillating water column (OWC) wave energy conversion device under the influence of unidirectional regular waves and optimizes the OWC device accordingly. The impact of different structural dimensions on the first-stage conversion efficiency of the OWC device is determined. Moreover, to evaluate the performance of the OWC device in real sea conditions, the wave climate at Sanmen Gorge is employed as the experimental parameter. The study examines the performance and characteristic response of the OWC device regarding the air chamber width, thickness of the front wall, and draught of the front wall. The findings reveal that the width of the OWC air chamber and the draught of the front wall significantly affect the OWC performance. Decreasing the width of the air chamber results in a stable horizontal plane, eliminating the occurrence of standing wave phenomena. As the draft of the front wall increases, the reflection coefficient of the air chamber gradually increases, and it becomes difficult for the wave to penetrate into the air chamber section. The Latin hypercube design experiment method was used to select experimental points and establish quadratic polynomial response functions. The OWC device was optimized based on multi-island genetic algorithm. The simulation and fault tolerant optimization methods presented in this paper can be widely used to improve system performance.