Conversion Of Potential Energy Research Articles

Structural and Environmental Characteristics of Western Baiu Frontal Depressions

Abstract Baiu frontal depressions (BFDs) are the major cyclones that form and develop along baiu fronts. The structure and environment of BFDs are examined using the Japanese 55-year Reanalysis dataset. BFDs detected automatically were categorized into four groups based on the region where the BFDs peaked: the East China Sea (ES), off the south coast of the Japanese islands (SC), the Yellow Sea (YS), and the Sea of Japan (SJ). A BFD-centered composite analysis demonstrates that, for YS-BFDs and SJ-BFDs, compared to ES-BFDs and SC-BFDs, the strength of upper-level troughs is greater, and the upper-level troughs are closer, suggesting that the effect of upper-level troughs on BFD development is greater. BFDs for all categories are located in the region of cyclonic horizontal shear and have a horizontal trough running from southwest to northeast, favoring barotropic energy conversion. The BFD-centered composite analysis of the energy conversion terms demonstrates that the barotropic energy conversion of mean kinetic energy due to the environmental cyclonic horizontal shear to eddy kinetic energy contributes to BFD development, and the conversion of eddy available potential energy, which is generated mainly by the diabatic heating, is the major contributor to eddy kinetic energy.

Directionally tailoring micro-nano hierarchical tower structured Mn0.6Ni1.4Co2Oy toward solar interfacial evaporation

Solar interfacial evaporation has been considered as a promising method to alleviate fresh water resources shortage. The shortage of freshwater resources requires advanced materials that can accelerate the evaporation of water by the sun. However, the simple structure of photothermal materials are vitally restricted by finite light absorption. Herein, this work presents a strategy for the synthesis of a spinel-type micro-nano hierarchical tower structure solar absorbent (Mn0.6Ni1.4Co2Oy) with the low forbidden band (=1.56 eV) and high absorption (97.88%). The products show great potential in solar-thermal energy conversion by creating a trapping effect. The prepared solar absorbent and epoxy resin are evenly mixed and then fully immersed in polyurethane (PU) sponge for water evaporation. The hydrophilic and porous Mn0.6Ni1.4Co2Oy @PU sponge can quickly deliver water upwards, suppress the heat loss, and concentrate the absorbed heat on the evaporation of water. The products exhibited an excellent evaporation rate of 2.261 kg m−2 h−1 and an impressive evaporation efficiency of 156% under a single sun exposure. Besides, the samples also can maintain the stability and recycling performance for a long time. These findings show that Mn0.6Ni1.4Co2Oy have great application prospects in the solar interfacial evaporation.

Tidal range resource of the Patagonian shelf

With vast potential for renewable energy conversion, the ocean could help reduce our reliance on fossil fuels. Of the various forms of ocean energy, tidal range power is both mature and predictable, dating back to 1966. However, only a few regions of the world are suited to tidal range power. Here, we examine the tidal range potential of the Patagonian shelf – estimated to contain over 100 GW of tidal dissipation. We use a high resolution global tidal atlas (TPXO9) to examine this resource from theoretical and technical perspectives. The theoretical resource is 913 TWh (104 GW) – considerably exceeding neighbouring Argentina’s electricity demand (∼143 TWh in 2021). We find that due to near-resonance with the semidiurnal tides, the resource is concentrated in two regions – Golfo de San Matías, and Bahía Grande to Río Grande. Three sites are chosen for further analysis after considering practical constraints such as water depth and proximity to the electricity grid. Through 0D modelling with tidal range power plant operation we find that the selected sites offer high energy extraction potential, exceeding 40% of the available resource. Further analysis shows how the combination of the sites can reduce the periods of no-generation to under 20%.

Analysis of Kinetic Energy Recovery Systems in Electric Vehicles

The recovery of kinetic energy (KER) in electric vehicles was analyzed and characterized. Two main systems were studied: the use of regenerative brakes, and the conversion of potential energy. The paper shows that potential energy is a potential source of kinetic energy recovery with higher efficiency than the traditional system of regenerative brakes. The study compared the rate of KER in both cases for a BMWi3 electric vehicle operating under specific driving conditions; the results of the analysis showed that potential energy conversion can recover up to 88.2%, while the maximum efficiency attained with the regenerative brake system was 60.1%. The study concluded that in driving situations with sudden and frequent changes of vehicle speed due to traffic conditions, such as in urban routes, the use of regenerative brakes was shown to be the best option for KER; however, in intercity routes, driving conditions favored the use of potential energy as a priority system for KER.

2D hexagonal boron nitride for solar energy conversions

The optoelectronic properties of free standing monolayer (ML) hexagonal boron nitride (h-BN) is investigated for potential solar energy conversion applications using the density functional theory (DFT) full potential linearized augmented plane wave (FP-LAPW) method. In addition, the bulk optical properties have also been calculated for the sake of comparison. The dielectric functions, optical conductivities and the optical constants are evaluated using the relaxed structures from electronic total energy pseudopotential calculations. The results reinforce previous research on h-BN DUV optoelectronics and demonstrate the suitability of its use as a component in deep ultraviolet (DUV) and energy conversion devices.

Pt-Mediated Interface Engineering Boosts the Oxygen Reduction Reaction Performance of Ni Hydroxide-Supported Pd Nanoparticles

Fuel cells are considered potential energy conversion devices for utopia; nevertheless, finding a highly efficacious and economical electrocatalyst for the oxygen reduction reaction (ORR) is of great interest. By keeping this in view, we have proposed a novel design of a trimetallic nanocatalyst (NC) comprising atomic Pt clusters at the heterogeneous Ni(OH)2-to-Pd interface (denoted NPP-70). The as-prepared material surpasses the commercial J.M.-Pt/C (20 wt %) catalyst by ∼ 166 and ∼19 times with exceptionally high specific and mass activities of 16.11 mA cm-2 and 484.8 mA mgPt-1 at 0.90 V versus reversible hydrogen electrode (RHE) in alkaline ORR (0.1 M KOH), respectively. On top of that, NPP-70 NC retains nearly 100% performance after 10k accelerated durability test (ADT) cycles. The results of physical characterization and electrochemical analysis confirm that atomic-scale Pt clusters induce strong lattice strain (compressive) at the Ni(OH)2-to-Pd interface, which triggers the electron relocation from Ni to Pt atoms. Such charge localization is vital for O2 splitting on surface Pt atoms, followed by the relocation of OH- ions from the Pd surface. Besides, a sharp fall down in ORR performance (mass activity is 37 mA mgPt-1 at 0.90 V versus RHE) is observed when the Pt clusters are decorated on the surface of NiOx and Pd (denoted NPP-RT). In situ partial fluorescence yield mode X-ray absorption spectroscopy (PFY-XAS) was employed to reveal the ORR pathways on both configurations. The obtained results demonstrate that interface engineering can be a potential approach to boost the electrocatalytic activity of metal hydroxide/oxide-supported Pd nanoparticles and in turn allow Pd to be a promising alternative for commercial Pt catalysts.

Encapsulation of tin oxide layers on gold nanoparticles decorated one-dimensional CdS nanoarrays for pure Z-scheme photoanodes towards solar hydrogen evolution

Despite their high potential for solar energy conversion into chemical fuels, most artificial all-solid-state Z-scheme photosystems have disordered structures and focus on power photocatalytic water splitting applications rather than photoelectrochemical (PEC) cells. Herein, an innovative pure Z-scheme heterostructure, CdS/Au/SnO2-S, composed of one-dimensional (1D) oriented CdS nanorods modified with SnO2-wrapped Au nanoparticles (NPs), was designed as a photoanode for highly efficient PEC hydrogen evolution. Systematic characterization confirms that the incorporated Au NPs not only act as the host platform to support the SnO2 layer growth but also play a key role as the electron mediator for strengthening the vectorial charge transfer from SnO2 to CdS. This reinforced Z-scheme charge transportation channel is favorable for suppressing the bulk charge recombination process, increasing the overall carrier density, and preserving the strong redox capability, ultimately resulting in a considerably improved photocurrent density and photo-to-current conversion efficiency with better corrosion resistance.

Starfish-like particles and nanowires interwoven architecture of CuO for water infiltration–induced electrical device

In the face of sustainable energy development, electricity generation using liquid infiltration in small-sized channels has become one of the effective strategies to optimize energy utilization. As p-type semiconductors, CuO nanomaterials exhibit great potential in energy storage and conversion, which can be used as suitable active materials for constructing nanogenerators. In this study, we proposed CuO water infiltration–induced electrical devices based on starfish-like particles and nanowires (NWs) interwoven architecture. Attributed to the ionovoltaic effect, the electrical signal value is reflected by the difference in carrier concentration between wet and dry regions. Notably, we innovatively used the oxidation–reduction–reoxidation method to control the crystal structure of CuO. In addition, we examined the relationship between CuO microstructure and performance and further explored the effect of different reaction conditions on the device output performance. It was demonstrated that a single device (7.5 cm × 2.5 cm × 18.3 µm) can generate an open-circuit voltage (Voc) of 0.67 V and a short-circuit current (Isc) of 2.49 μA at room temperature when 30 μL of 0.1 mol L−1 NaCl solution permeates from one end of the film. Under a 0.5 mol L−1 NaCl condition (seawater concentration), the device can generate a Voc of 0.82 V and an Isc of 2.70 μA, which is expected to be utilized in the field of sensors for identifying the different concentrations of ions.

Hydrostatic and Non‐Hydrostatic Baroclinic Instability in the Dynamical Core of the DOE Global Climate Model

AbstractThe dynamical core of the Department of Energy global climate model is used to understand the role of non‐hydrostatic dynamics in the simulation of dry and moist baroclinic waves. To reduce computational cost, the Diabatic Acceleration and REscaling approach is adopted. Scale analysis and numerical simulations suggest that the model solution is not distorted by the change of spherical metric terms due to the change of Earth radius, neither are the inter‐scale interactions strongly altered as indicated by the analysis of spectral flux. Compared with hydrostatic simulations, the onset of baroclinic instability is delayed under non‐hydrostatic dynamics as the associated weaker vertical motions tend to increase the critical wavelength and narrow the range of waves that can be baroclinically unstable. During the development of baroclinic waves, non‐hydrostatic dynamics tends to induce vertical motions in the upper troposphere, accelerating the eastward propagation of upper‐level ridges through their impact on local vorticity tendency. These processes reduce the westward tilt of the vertical ridge axes and suppress the conversion of mean flow available potential energy to eddy kinetic energy, leading to weaker baroclinic eddies than in hydrostatic simulations. The contrasts between hydrostatic and non‐hydrostatic settings hold in supplemental experiments that vary the background flow Rossby number, the amount of water vapor content and vertical resolution. We also find that mesoscale and smaller‐scale activities can be considerably under‐represented when the vertical resolution is limited to that typically used in global climate models.

Polysulfides manipulation: Constructing g-C3N4 networks encapsulated into natural wood fibers for high-performance lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) have become a dominant potential energy storage and conversion system because of their high theoretical specific capacity and energy density. Nevertheless, the shuttle effect and slow redox kinetics of polysulfides severely impede the wide application of LSBs. Herein, for polysulfide manipulation, a g–C3N4 network structure was creatively constructed in N, S co-doped carbonized wood fiber lumen (NSPCF@CN) using an etching induction strategy. Benefiting from the desirable characteristics endowed by the CN network structure, such as large specific surface area, special interfacial C–N–C bond, the composite with high activity improves the redox kinetics of polysulfides, alleviates the shuttle effect, and reduces the volume change during charging and discharging. As expected, the cathode made from NSPCF@CN–10 and sulfur composite (NSPCF@CN–10/S) possesses a remarkable specific capacity of 1590.8 mAh g−1 at 0.5 C, and a high-rate capability of 976.9 mAh g−1 at 2.0 C. More interestingly, a reversible capacity as high as 781 mAh g−1 over 1000 cycles at 1.0 C is achieved. Density functional theory calculations reveal that the synergistic effect of N, S co-doping and CN network structure can effectively improve the adsorption capacity of polysulfide. This approach of constructing the network structure in natural wood fiber lumen provides a new vision for addressing the complex problems associated with LSBs.

Occurrence and development criteria of coal and gas outbursts based on energy conversion

Coal and gas outbursts are sudden disasters in coal mines, they are major dynamic hazard during coal mining and have to be controlled for mining safety. To further understand the outburst process of coal and gas outbursts, an energy conversion model of coal and gas outbursts are established from the perspective of outburst energy conversion, and the criteria of outburst occurrence and development are determined. The energy conversion relationship and criteria of outburst occurrence and development are analyzed by physical simulation experiments. The results show that the critical threshold of the two groups of experiments is 2600 J. When the outburst potential energy exceeds the critical threshold, the outburst phenomenon occurs. Some of the outburst potential energy is converted into effective outburst potential energy to participate in the outburst work with the outburst process. The effective potential energy conversion rate of the two groups is 52 %-55 %. In the outburst of each experiment with outburst phenomenon, the development criterion values are 1.16–1.20 for experimental group 1, and the values are 3.06–3.75 for experimental group 2. The result indicates that the necessary condition for outburst development is that the outburst effective potential energy is sufficient to overcome the outburst energy consumption. This study will be of great scientific significance for exploring the outburst mechanism.

Three-Dimensional Numerical Simulation of the Performance and Transport Phenomena of Oxygen Evolution Reactions in a Proton Exchange Membrane Water Electrolyzer.

Proton exchange membrane (PEM) water electrolysis, which is one of methods of hydrogen production with the most potential, has attracted more attention due to its energy conversion and storage potential. In this paper, a steady state, three-dimensional mathematical model coupled with the electrochemical and mass transfer physical fields for a PEM water electrolyzer was established. The influence of the different operation parameters on the cell performance was discussed. Moreover, the different patterns of the flow field, such as parallel, serpentine, multi-serpentine, and interdigitate flow fields, were simulated to reveal their influence on the mass transfer and current distribution and how they consequently affected the cell performance. The results of the numerical modeling were in good agreement with the experimental data. The results demonstrated that a higher temperature led to a better mass transfer, current distribution, and cell performance. By comparing the polarization curve, current, velocity, and pressure distribution, the results also indicated that the PEM water electrolyzer with a parallel flow field had the best performance. The results in this study can help in optimizing the design of PEM water electrolyzers.

Energetics of Eddy–Mean Flow Interactions in the East Australian Current System

Abstract Examining eddy–mean flow interactions in western boundary currents is crucial for understanding the mechanisms of mesoscale eddy generation and the role of eddies in the large-scale circulation. However, this analysis is lacking in the East Australian Current (EAC) system. Here we show the detailed three-dimensional structure of the eddy–mean flow interactions and energy budget in the EAC system. The energy reservoirs and conversions are greatest in the upper 500 m, with complex vertical structures. Strong mean kinetic energy is confined within a narrow band (24.5°–32.5°S) in the EAC jet. Most energy is contained in the eddy fields instead of the mean flow in the EAC typical separation and extension regions (south of 32.5°S). Strong barotropic instability is the primary source of eddy kinetic energy north of 36°S, while baroclinic instability dominates the eddy kinetic energy production in the EAC southern extension, which peaks in the subsurface. The mean flow transfers 5.22 GW of kinetic energy and 3.33 GW of available potential energy to the eddy field in the EAC typical separation region. The largest conversion term is from available potential energy conversion from the mean flow to the eddy field through baroclinic instability, dominating between 29° and 35.5°S. Nonlocal eddy–mean flow interactions also play a role in the energy exchange between the mean flow and the eddy fields. This study provides the mean state of the eddy–mean flow interactions in the EAC system, paving the way for further studies exploring seasonal and interannual variability and provides a baseline for assessing the impact of environmental change.

Submesoscale dynamics accompanying the Kuroshio in the East China Sea

Submesoscale processes in the ocean are vital for sustaining energy balance across scales. Taking advantage of the high resolution and wide coverage of numerical simulations, which are currently lacking for field observations, we investigated the basic patterns of submesoscale dynamics and mechanisms of corresponding variabilities along with the Kuroshio in the East China Sea. The large-scale western boundary jet serves as a remarkable submesoscale energy reservoir, promoted by steep topographic features. In the discovered hotspots, that is, the continental slope and lee area of the Tokara Strait, long-lasting submesoscale footprints arose in the form of linear patterns of strongly skewed Rossby numbers with maximum values of ~O(1). Their origin may be derived from the high topographically induced strain rate, which shows a consistent distribution and high correlation with the Rossby number. Corresponding to the characteristics of such active submesoscale processes, kinetic energy wavenumber spectra were visibly flatter than previous estimations of typical two-dimensional geostrophic turbulence and were not temporally fixed under the combined effects of multiple factors. The annual cycle of stratification induces seasonality by affecting mixed-layer instabilities, which control the kinetic and potential energy conversion rates. The tidal periods may be due to tides generating inertia-gravity waves that partially overlap in submesoscale ranges. Various other intermediate periods of variability were probably related to the eddy-caused Kuroshio path meander, which implied a closely coupled dynamical system across scales. Uncertainties come from the ascertainment of the specific contribution ratios of each part, which will be studied in the future.

Preliminary gas flow experiments identify improved gas flow conditions in a pilot-scale trickle bed reactor for H2 and CO2 biological methanation

Biological methanation of H2 and CO2 is a potential energy conversion technology that can support the energy transition based on renewable sources. The methanation performance in trickle bed reactors can be improved by approaching the gas flow through the reactor towards plug flow. Through preliminary gas flow experiments without biological conversion, this study investigated operational and constructional conditions that enhance plug flow in a pilot-scale trickle bed reactor with 1 m3 gas volume. An improved gas flow was observed when the feed gas was applied in a top-to-bottom direction and when the process liquid was not trickled through the packing bed. Furthermore, the gas flow experiments identified reactor-specific properties, such as unused or dead volumes. Applying gas flow experiments prior to reactor start-up is recommended as a simple and convenient method to identify individual reactor properties and optimization potentials for higher methanation performance.

Functional Metal/Carbon Composites Derived from Metal–Organic Frameworks: Insight into Structures, Properties, Performances, and Mechanisms

Metal–organic frameworks (MOFs) have extensively emerged as promising templates/precursors to prepare functional derivatives for various purposes because of their ultrahigh porosity, large specific surface area, and excellent user-configuration flexibility. Among these derivatives, MOFs-derived metal/carbon composites surmount the shortcomings of the individual components and produce synergistic effects, showing great potential in environmental remediation and energy storage and conversion. Herein, this work systematically discusses the synthetic strategies of MOFs-derived metal/carbon composites from the perspective of different MOF precursors, including pristine MOFs, heteroatom-doped MOFs, and MOFs composited with substrates. The unique advantages of MOFs-derived metal/carbon composites with exceptional stability, conductivity, and catalytic activity are then particularly summarized. On the basis of these advantages, their recent progress in the environment and energy fields is elaborated, with special emphasis on the elucidation of their mechanisms. Finally, the challenges and opportunities for future research are presented, which is expected to provide references for the design of multipurpose MOFs-derived metal/carbon composites.

Tunable Ion Transport in Two-Dimensional Nanofluidic Channels

Layered two-dimensional (2D) materials with interlayer channels at the nanometer scale offer an ideal platform to control ion transport behaviors, including high-precision separation, ultrafast diffusion, and tunable permeation flux, which show great potential for energy conversion and storage, water treatment, catalysis, biosynthesis, and sensing. Recent advances in controlling the structure and functionality of 2D nanofluidic channels sustainably open doors for more revolutionary applications. In this Perspective, we first present a brief introduction to the fundamental mechanisms for ion transport in 2D nanofluidic channels and an overview of state-of-the-art assembly technologies of nanochannel membranes. We then point out new avenues for developing advanced nanofluidics, combining molecular-level cross-linking, and surface modification in nanoconfinement. Finally, we outline the potential applications of these 2D nanofluidic channel membranes and their technical challenges that need to be addressed to afford for practical applications.

Enhanced osmotic energy conversion through bacterial cellulose based double-network hydrogel with 3D interconnected nanochannels

Hydrogel with 3D networks have shown great potential for ion transportation and energy conversion. However, the micron size pores of hydrogel greatly limit the ion selectivity and energy conversion performance. Here, we report a bacterial cellulose (BC) derived hydrogel membrane with double-network (DN) and tailored ion transport channels by rationally filling acrylic acid (AAc)-co-acrylamide (AAm)-co-methyl methacrylate (MMA) polymers into BC hydrogel micropores. Fabricated AAM/BC DN hydrogel membrane displays a unique hierarchical interconnected porous structure and 3D cation transport channels. From the results, the maximum power density reached up to 7.63 W·m−2 at 50-fold salinity gradient under alkaline conditions (pH 11). Interestingly, the power density of 45.5 W·m−2 was achieved through acid-base neutralization reaction. Furthermore, hydrogel successfully obtained a power density of 28.4 W·m−2 from a mixed system of paper black liquor wastewater/seawater. The results of this investigation suggested the enormous potential of BC-based nanofluidic membrane in sustainable osmotic energy conversion.

Magnetically retrievable Fe3O4@SiO2@ZnO piezo-photocatalyst: Synthesis and multiple catalytic properties

The piezo-/photocatalytic effects of ZnO have been in the limelight because of their great potential in environmental remediation and energy conversion. However, the poor recyclability of the suspended catalysts can cause inevitable secondary pollution, which is one of the major issues that limit the practical application of these materials. To address this problem, a magnetically retrievable Fe3O4@SiO2@ZnO nanocomposite was designed and successfully synthesized by multi-step reactions. The ZnO nanorods were vertically grown on the surface of the magnetic Fe3O4@SiO2 microspheres, while SiO2 served as an insulator to protect the inner core and to inhibit charge transfer across the core/shell interface. The Fe3O4@SiO2@ZnO nanocomposite can be easily collected and separated by using a magnetic field. Along with the good recyclability, the material also exhibited high efficiencies in piezocatalytic, photocatalytic and piezo-photocatalytic dye degradation processes. The rate constant of piezo-photocatalysis reached 95.9 × 10−3 min−1, which was 2.2 and 6.1 times that of the individual piezocatalysis and photocatalysis, respectively. The present result confirmed the existence of a synergetic effect between piezo- and photocatalytic processes. Hereby, we demonstrated that incorporation of a magnetic carrier is a feasible strategy to achieve retrievable and highly efficient piezo-/photocatalyst.

Renaissance of elemental phosphorus materials: properties, synthesis, and applications in sustainable energy and environment.

The polymorphism of phosphorus-based materials has garnered much research interest, and the variable chemical bonding structures give rise to a variety of micro and nanostructures. Among the different types of materials containing phosphorus, elemental phosphorus materials (EPMs) constitute the foundation for the synthesis of related compounds. EPMs are experiencing a renaissance in the post-graphene era, thanks to recent advancements in the scaling-down of black phosphorus, amorphous red phosphorus, violet phosphorus, and fibrous phosphorus and consequently, diverse classes of low-dimensional sheets, ribbons, and dots of EPMs with intriguing properties have been produced. The nanostructured EPMs featuring tunable bandgaps, moderate carrier mobility, and excellent optical absorption have shown great potential in energy conversion, energy storage, and environmental remediation. It is thus important to have a good understanding of the differences and interrelationships among diverse EPMs, their intrinsic physical and chemical properties, the synthesis of specific structures, and the selection of suitable nanostructures of EPMs for particular applications. In this comprehensive review, we aim to provide an in-depth analysis and discussion of the fundamental physicochemical properties, synthesis, and applications of EPMs in the areas of energy conversion, energy storage, and environmental remediation. Our evaluations are based on recent literature on well-established phosphorus allotropes and theoretical predictions of new EPMs. The objective of this review is to enhance our comprehension of the characteristics of EPMs, keep abreast of recent advances, and provide guidance for future research of EPMs in the fields of chemistry and materials science.