Energy Mismatch Research Articles

Does New Urbanization Promote Urban Metabolic Efficiency?

Existing studies have paid less attention to the impact of new urbanization (NU) on urban metabolic efficiency (UME). This paper empirically tests the mechanism and the effect of NU on UME based on China’s panel data from 2008 to 2020, using China’s NU pilot as a quasi-natural experiment. The study draws the following conclusions: (1) NU can significantly promote UME. (2) NU can promote UME for cities in neighboring regions. (3) The effect of NU on UME presents the heterogeneous characteristics of eastern region > central region > western region, non-urban agglomeration cities > urban agglomeration cities, and is greater in central cities than in non-central cities. (4) Mechanism analysis shows that NU can promote UME through six paths: promoting urban–rural integration and regional synergistic development, reducing urban sprawl and energy mismatch, strengthening urban–rural population mobility, and green innovation division of labor. The above results are not only conducive to incorporating UME into NU’s appraisal system but also to making UME, which can reflect the quality of urban development in a more comprehensive and systematic way, a performance measurement tool for NU.

Effect of silver inhibition on the ceramic foam as flame suppression

Aluminium dust explosions pose significant safety and economic challenges in various industrial processes. Due to this, the current research explores an innovative approach by inhibiting the silver nanoparticles (Ag NPs) to ceramic porous form substrate as a flame suppressant in order to mitigate the risks associated with these explosions. The antimicrobial and non-toxic qualities of silver are also attractive to be applied in medical and food technology. However, the interfacial adhesion between the metallic (nanosilver) and non-metallic (silica-based-ceramic) is still vaguely studied due to the mechanical and surface energy mismatch between the organic surface and the inorganic layers. From this study, the physicochemical and mechanical properties of the silver-coated ceramic foam were analyzed using X-ray diffraction, field emission scanning electron microscopy with energy dispersive X-ray, thermogravimetric analysis, and compression test. From the mechanical testing, it was found that the percentage increase of maximum load for silver-ceramic foam from the original ceramic foam was about 60%. The results indicate that silver-coated foam has a better compressive strength of 0.93 MPa as compared to 0.58 MPa by the original ceramic. The inhibition effect of Ag NPs powder on the explosion pressure evolution and flame spread mechanism of aluminium powder at different concentrations and particle sizes was tested using the Hartmann experimental system.

Cross Relaxation Enables Spatiotemporal Color-Switchable Upconversion in a Single Sandwich Nanoparticle for Information Security.

Smart control of ionic interaction dynamics offers new possibilities for tuning and editing luminescence properties of lanthanide-based materials. However, it remains a daunting challenge to achieve the dynamic control of cross relaxation mediated photon upconversion, and in particular the involved intrinsic photophysics is still unclear. Herein, this work reports a conceptual model to realize the color-switchable upconversion of Tm3+ through spatiotemporal control of cross relaxation in the design of NaYF4:Gd@NaYbF4:Tm@NaYF4 sandwich nanostructure. It shows that cross relaxation plays a key role in modulating upconversion dynamics and tuning emission colors of Tm3+. Interestingly, it is found that there is a short temporal delay for the occurrence of cross relaxation in contrast to the spontaneous emission as a result of the slight energy mismatch between relevant energy levels. This further enables a fine emission color tuning upon non-steady state excitation. Moreover, a characteristic quenching time is proposed to describe the temporal evolution of cross relaxation quantitatively. These findings present a deep insight into the physics of ionic interactions in heavy doping systems, and also show great promise in frontier applications including information security, anti-counterfeiting and nanophotonics.

An electrothermally actuated twisted-coiled nylon spring with surface electroless deposited copper coatings

Electrothermally-driven artificial muscles have attracted widespread attention due to their low cost and high power density. However, their actuation performance is severely limited by the modulus and surface energy mismatch between the conductive coatings and substrates. Herein, a novel fabrication strategy that integrates surface-initiated atom transfer radical polymerization (SI-ATRP) and electroless deposition (ELD) is proposed to solve this issue, and a copper-coated twisted-coiled nylon spring (Cu-TCNS) that exhibits satisfactory actuation performance is realized for the first time. The ingeniously designed Cu-TCNS successfully lifts a load equivalent to 380 times its own weight within 4 s, achieving satisfactory contraction ratio (42.85%), repeatability (>1000 cycles), and energy/power density (67.78 J/Kg and 16.95 W/Kg). Such an inspiring strategy proposed in this work is supposed to provide guidance for the design and fabrication of excellent artificial muscle in future research.

An IoT-fog-cloud consensus-based energy management algorithm of multi-agent smart energy hubs considering packet losses and uncertainty

—As a result of the increasing demand for different energies with technological development, and with the rapid development of energy hubs (EHs), issues such as computation speed, big data and information privacy, robustness, etc. are becoming increasingly vital. Also, the problem of communication packet loss leads to an incompatibility between the generated and consumed energy. In response to the above problems, this paper proposes an Internet of things-Fog-Cloud distributed consensus-based energy management algorithm to optimally solve the energy mismatch problem in an EH environment considering communication information loss and uncertainties of some EH elements. A MATLAB/Simulink-based model of a hypothetical EH system is modified to support real-time communication. Two case studies are applied to explain the performance and effectiveness of the proposed algorithm under different packet loss scenarios. The system's sensitivity was studied depending on the number of iterations and the uncertainties of the renewable energy sources, energy prices, and load demands. Also, a comparison was made between the results obtained by the proposed method and the optimization results using the genetic algorithm and particle swarm optimization techniques. The results prove the applicability and feasibility of the proposed method for the demand management system in EHs. The results show that the proposed algorithm decreases the daily system operating cost from 372.421 to 369.941 $ and the total CO2 emissions cost from 4848.5 to 4103.1 $. In addition, the daily energy mismatch between the generated and consumed values decreases from 579.85 to 0 kWh in the electrical system and from 435.14 to 0.073 kWhth in the heating system. Based on the previous results, the proposed algorithm of EHs contributes significantly to the development of sustainable cities.

Synchronous Elimination of Excess Photoinstable PbI2 and Interfacial Band Mismatch for Efficient and Stable Perovskite Solar Cells.

Eliminating the undesired photoinstability of excess lead iodide (PbI2 ) in the perovskite film and reducing the energy mismatch between the perovskite layer and heterogeneous interfaces are urgent issues to be addressed in the preparation of perovskite solar cells (PVSCs) by two-step sequential deposition method. Here, the 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4 ) is employed to convert superfluous PbI2 to more robust 1D EMIMPbI3 which can withstand lattice strain, while forming an interfacial dipole layer at the SnO2 /perovskite interface to reconfigure the interfacial energy band structure and accelerate the charge extraction. Consequently, the unencapsulated PVSCs device attains a champion efficiency of 24.28 % with one of the highest open-circuit voltage (1.19 V). Moreover, the unencapsulated devices showcase significantly improved thermal stability, enhanced environmental stability and remarkable operational stability accompanied by 85 % of primitive efficiency retained over 1500 h at maximum power point tracking under continuous illumination.

Synchronous Elimination of Excess Photoinstable PbI2 and Interfacial Band Mismatch for Efficient and Stable Perovskite Solar Cells

AbstractEliminating the undesired photoinstability of excess lead iodide (PbI2) in the perovskite film and reducing the energy mismatch between the perovskite layer and heterogeneous interfaces are urgent issues to be addressed in the preparation of perovskite solar cells (PVSCs) by two‐step sequential deposition method. Here, the 1‐ethyl‐3‐methylimidazolium tetrafluoroborate (EMIMBF4) is employed to convert superfluous PbI2 to more robust 1D EMIMPbI3 which can withstand lattice strain, while forming an interfacial dipole layer at the SnO2/perovskite interface to reconfigure the interfacial energy band structure and accelerate the charge extraction. Consequently, the unencapsulated PVSCs device attains a champion efficiency of 24.28 % with one of the highest open‐circuit voltage (1.19 V). Moreover, the unencapsulated devices showcase significantly improved thermal stability, enhanced environmental stability and remarkable operational stability accompanied by 85 % of primitive efficiency retained over 1500 h at maximum power point tracking under continuous illumination.

Inorganic Nanoparticles Embedded in Polydimethylsiloxane Nanodroplets.

To stabilize and transport them through complex systems, nanoparticles are often encapsulated in polymeric nanocarriers, which are tailored to specific environments. For example, a hydrophilic polymer capsule maintains the circulation and stability of nanoparticles in aqueous environments. A more highly designed nanocarrier might have a hydrophobic core and a hydrophilic shell to allow the transport of hydrophobic nanoparticles and pharmaceuticals through physiological media. Polydimethylsiloxane, PDMS, is a hydrophobic material in a liquid-like state at room temperature. The preparation of stable, aqueous dispersions of PDMS droplets in water is problematic due to the intense mismatch in surface energies between PDMS and water. The present work describes the encapsulation of hydrophobic metal and metal oxide nanoparticles within PDMS nanodroplets using flash nanoprecipitation. The PDMS is terminated by amino groups, and the nanodroplet is capped with a layer of poly(styrenesulfonate), forming a glassy outer shell. The hydrophobic nanoparticles nucleate PDMS droplet formation, decreasing the droplet size. The resulting nanocomposite nanodroplets are stable in aqueous salt solutions without the use of surfactants. The hierarchical structuring, elucidated with small-angle X-ray scattering, offers a new platform for the isolation and transport of hydrophobic molecules and nanoparticles through aqueous systems.

Design optimization of energy systems for zero energy buildings based on grid-friendly interaction with smart grid

Zero-energy buildings usually achieve annual net-zero energy balance by generating electricity using on-site renewable energies and interconnecting with the power grid. However, the impact of energy mismatch problem in zero-energy buildings design on the grid is often overlooked, which potentially compromises grid's stability. To address this issue, this paper presents an optimization design method based on "grid-friendly interaction" which optimizes the energy system of zero-energy buildings to ensure better alignment between the building's electricity purchase/sale and grid demand. In this study, an indicator of "grid-friendly interaction", which represents the ratio of the net building friendly interaction power to the total annual interaction power, is firstly established to guide buildings in improving their interaction with the grid. Next, the energy supply, demand, and storage schemes of renewable energy systems in the zero-energy building are iteratively adjusted to achieve the best match with grid's expectations. This optimization design method was applied to a practical case in Hong Kong. Results show that, compared to the benchmark building, the optimal system design scheme increases grid friendliness by 83 %, reduces carbon dioxide emissions by 77 %, but also incurs a total cost increase of 180 %. The optimization design method proposed in this paper can effectively mitigate the impact of zero-energy buildings on the power grid, fostering enhanced interplay between the building structures and the grid. The study significantly contributes to the advancement of exploring the potential for energy flexibility in zero-energy buildings, which is of great significance for the safe and stable operation of future grids. The purpose of this study is to explore the energy flexibility potential of zero-energy buildings, which is of great significance for the safe and stable operation of future grids.

Octylammonium Iodide Induced In-situ Healing at "perovskite/Carbon" Interface to Achieve 85% RH-moisture Stable, Hole-Conductor-Free Perovskite Solar Cells with Power Conversion Efficiency >19.

"Perovskite/carbon" interface is a bottle-neck for hole-conductor-free, carbon-electrode basing perovskite solar cells due to the energy mismatch and concentrated defects. In this article, in-situ healing strategy is proposed by doping octylammonium iodide into carbon paste that used to prepare carbon-electrode on perovskite layer. This strategy is found to strengthen interfacial contact and reduce interfacial defects on one hand, and slightly elevate the work function of the carbon-electrode on other hand. Due to this effect, charge extraction is accelerated, while recombination is obviously reduced. Accordingly, power conversion efficiency of the hole-conductor-free, planar perovskite solar cells is upgraded by ≈50%, or from 11.65 (± 1.59) % to 17.97 (± 0.32) % (AM1.5G, 100mWcm-2 ). The optimized device shows efficiency of 19.42% and open-circuit voltage of 1.11V. Meanwhile, moisture-stability is tested by keeping the unsealed devices in closed chamber with relative humidity of 85%. The "in-situ healing" strategy helps to obtain T80 time of >450h for the carbon-electrode basing devices, which is four times of the reference ones. Thus, a kind of "internal encapsulation effect" has also been reached. The "in situ healing" strategy facilitates the fabrication of efficient and stable hole-conductor-free devices basing on carbon-electrode.

Ternary-Metal Sn-Pb-Zn Perovskite to Reconstruct Top Surface for Efficient and Stable Less-Pb Perovskite Solar Cells.

Though Sn-Pb alloyed perovskite solar cells (PSCs) achieved great progress, there is a dilemma to further increase Sn for less-Pb requirement. High Sn ratio (>70%) perovskite exhibits nonstoichiometric Sn:Pb:I at film surface to aggravate Sn2+ oxidation and interface energy mismatch. Here, ternary metal alloyed (FASnI3 )0.7 (MAPb1- x Znx I3 )0.3 (x = 0-3%) is constructed for Pb% < 30% perovskite. Zn with smaller ionic size and stronger ionic interaction than Sn/Pb assists forming high-quality perovskite film with ZnI6 4- enriched at surface to balance Sn:Pb:I ratio. Differing from uniform bulk doping, surface-rich Zn with lower lying orbits pushes down the energy band of perovskite and adjusts the interface energy for efficient charge transfer. The alloyed PSC realizes efficiency of 19.4% at AM1.5 (one of the highest values reported for Pb% < 30% PSCs). Moreover, stronger bonding of Zn─I and Sn─I contributes to better durability of ternary perovskite than binary perovskite. This work highlights a novel alloy method for efficient and stable less-Pb PSCs.

Temporal and spatial patterns, efficiency losses and impact factors of energy mismatch in China under environmental constraints

Given the evident spatial disparity in China's energy consumption and economic development, achieving Pareto optimization of regional energy allocation efficiency proves to be a formidable challenge. Based on this, this paper ingeniously proposed an extended “labor-capital-energy-environment” resource mismatch mode, using 2004–2018 provincial panel data to measure and analyze the spatiotemporal pattern of China's energy mismatch and efficiency loss, while further investigating influencing factor. The results show that: (1) Although the degree of resource misallocation has decreased, the reduction of the number of provinces with excessive energy allocation and the serious shortage of energy allocation are the only effects of the optimization of energy resource misallocation, which has not significantly improved the situation overall. (2) Energy resource misallocation has grown to be a significant factor in China's losses in green total factor productivity (GTFP) brought on by resource misallocation. In addition, the extent of energy mismatch's loss in GTFP demonstrates the spatial heterogeneity of the “eastern > central > northeast > west” region. (3) Environmental regulation can significantly reduce energy mismatch and it is more successful at addressing the issue of excess energy than inadequate energy allocation. Also, the “rebound effect” of technological progress is the main factor aggravating the shortage of energy allocation.

KNN-based optical temperature sensing ceramics integrating negative thermal quenching and photochromic self-recovery behavior

Rare-earth ion (RE3+) doped materials with upconversion luminescence and photochromic (PC) effect have received widespread attention, but thermal quenching (TQ) at high temperature and energy-demanding PC recovery processes limit their practical applications. Herein, lanthanide ion doped (K0.5Nb0.5)NbO3 (KNN) based translucent ceramics were prepared, in which Tm3+/Yb3+ co-doped one displays optical versatility for potential applications in temperature sensors and anti-counterfeiting. By utilizing the large energy mismatch between Tm3+ and Yb3+, negative thermal quenching (NTQ) feature was achieved with the maximum relative sensitivity of 2.54 %K−1 at 213 K. Furthermore, by constructing appropriate intermediate traps, the ceramic exhibits a rapid PC self-recovery process within 30 min without external stimulation. The bifunctional specialty can expand the applications of KNN-based ceramics in optical area.

Tm3+-doped upconversion nanoparticles water probing

Water probing based on lanthanide-doped upconversion nanoparticles (UCNPs) has aroused great interest due to the advantages of high photostability, short response time, no autofluorescence background, and low toxicity. Compared with widely used Er3+-doped UCNPs, Tm3+-doped UCNPs are not considered as efficient water probes due to the phonon energy mismatch. Here, we demonstrate the water probing based on Tm3+-doped UCNPs with excellent sensitivity and linearity, and reveal that the fractional photon-assisted Förster resonance energy transfer could play a significant role in the mechanism. The recorded sensitivities of up to 6.141%/vol% and 3.932%/vol% were achieved for the hydrogen oxide and deuterium oxide detection. Based on the developed UCNPs, we developed two sensing devices, namely, an UCNPs-coated micro-fiber and UCNPs-embedded silk, for distributed and wearable humidity sensing. Our study opens an unprecedented avenue to develop real-time, high-sensitivity, high-stability, biocompatible water probes serving the fields of cytobiology, pharmaceutics, environmental health and safety, fine chemical industry, and precision agriculture.

Comparative assessment of multi-objective optimization of hybrid energy storage system considering grid balancing

With the accelerated transition towards affordable and clean energy sources, the energy sector is undergoing a structural transformation that has resulted in a further increase in the complexity of energy system planning with rapid changes in techno-economic, environmental, reliability and social constraints. This signifies the consideration of purpose-driven multi-objective functions depending upon the functionality and applicability of the model. However, most of the studies adopt conventional bi-objective optimization either involving techno-economic, reliability and grid balancing parameters but there is a lack of comparative assessment of multi-objective optimization sizing for grid-interactive hybrid renewable energy system (HRES) consisting of short and long-term, battery and pumped hydro storage (PHS), energy storage systems (ESS). This study presents a comparative multi-objective framework to assess bi- and tri-objective function sizing techniques under grid balancing and non-balancing modes, to understand the scope and adaptivity of the modeling process for large-scale grid-interactive HRES. The analysis of results shows that the non-balancing mode underestimates the cost of energy (COE) by 18–30% compared to the grid balancing mode due to smaller decision variable space while long-term ESS dominance is vital for the reduction of grid burden compared to short-term ESS. In terms of configuration, a hybrid ESS system, 0.22 MWh battery, 18.1 MWh PHS, and 5.4 MW PV capacity, is the best optimal configuration in grid balancing mode with the COE, EEI and EII equal to 0.09 $/kWh, 7.5% and 10.5% respectively, whereas higher grid energy mismatch is induced by non-balancing mode with the overestimation of EEI and EII indexes up to 30% and 33% respectively. The environmental analysis shows that the carbon emissions avoided (CEA) are underestimated by 59.1% with the non-consideration of grid balancing. This signifies that the adaptive optimization model improves the design and planning process of grid-interactive HRES by capturing larger uncertainties related to COE, grid balancing, and CEA with changes in the system and ESS sizing. Overall, this analysis provides a purpose-driven perspective to energy modelers and policymakers for the energy system modeling process of grid-interactive HRES.

Metallic nanoparticles-decorated NdxY1-xAl3(BO3)4 sub-micrometric particles to enhance anti-Stokes excitation performance

In the anti-Stokes excitation of trivalent rare-earth ions (RE3+), the excitation photons energy is smaller than that of a given absorption transition, and the energy mismatch can be compensated by phonons annihilation from the host lattice. Since the phonon occupation number increases with temperature, heating the system generally increases the efficiency of anti-Stokes excitation. Here, we exploited the intrinsic heating associated with light-to-heat conversion in the interaction of excitation laser light with metallic nanoparticles (Ag or Au) on the surface of submicrometric particles of NdxY1.00-xAl3(BO3)4 (x = 0.10, 0.20, and 1.00) in order to enhance the efficiency of the anti-Stokes excitation at 1064 nm. Several upconversion emissions are observed from 600 nm to 880 nm, the most intense being at 750 nm due to the Nd3+ transition {4F7/2, 4S3/2} → 4I9/2. Giant enhancements are demonstrated, when compared to undecorated NdxY1.00-xAl3(BO3)4 particles. The present results can be expanded to other luminescent materials as well as excitation wavelengths.

A New Insight into the Singlet Oxygen Mechanism for Photodynamic Therapy.

Modern photodynamic therapy has been built on the mechanism of the interaction between the photosensitizer (porphyrin derivatives) and oxygen to produce singlet oxygen, which relies on energy transfer from the triplet excited state (T1) of porphyrin to the excited state of oxygen. In this process, the energy transfer from the singlet excited state (S1) of porphyrin to oxygen is believed to be not pronounced as the rapid decay of S1 and the large energy mismatch. Here, we have evidenced the existence of an energy transfer between S1 and oxygen, which can contribute to the production of singlet oxygen. For hematoporphyrin monomethyl ether (HMME), the Stern-Volmer constant of S1 (KSV') is 0.023 kPa-1, according to the oxygen concentration-dependent steady fluorescence intensities. In addition, fluorescence dynamic curves of S1 under various oxygen concentrations have also been measured through ultrafast pump probe experiments to further verify our results.

Improving perovskite/P3HT interface without an interlayer: Impact of perovskite surface topography on photovoltaic performance of P3HT-based perovskite solar cells

The photovoltaic performance of poly(3-hexylthiophene) (P3HT)-based perovskite solar cells is inferior due to the improper perovskite/P3HT interface caused by a surface energy mismatch. The most promising method to improve the interface is the introduction of interlayers between perovskite and P3HT layers; however, this increases fabrication complexity and irreproducibility. Here, we show how the surface topography of the perovskite layer can improve the interface without an interlayer. To explore this, we varied surface topography by altering the crystal size of the methylammonium lead iodide through its deposition temperature namely, 10 0C and 30 0C. The solar cells based on the perovskite layers formed at 10 0C outperform the cells fabricated from perovskite layers deposited at 30 0C. Our studies reveal that the surface topography of the perovskite layer influences the surface energy that impacts the interface between perovskite and P3HT layers, consequently enhancing recombination resistance, short-circuit current, and open-circuit voltage, ultimately improving photovoltaic performance. Modification of surface topography is a simple approach to improve the perovskite/P3HT interface without an interlayer and can lead to better performance in P3HT-based perovskite solar cells.

Engineered entropic forces allow ultrastrong dynamical backaction.

When confined within an optical cavity light can exert strong radiation pressure forces. Combined with dynamical backaction, this enables important processes, such as laser cooling, and applications ranging from precision sensors to quantum memories and interfaces. However, the magnitude of radiation pressure forces is constrained by the energy mismatch between photons and phonons. Here, we overcome this barrier using entropic forces arising from the absorption of light. We show that entropic forces can exceed the radiation pressure force by eight orders of magnitude and demonstrate this using a superfluid helium third-sound resonator. We develop a framework to engineer the dynamical backaction from entropic forces, applying it to achieve phonon lasing with a threshold three orders of magnitude lower than previous work. Our results present a pathway to exploit entropic forces in quantum devices and to study nonlinear fluid phenomena such as turbulence and solitons.

Optimal coordinated energy management strategy for standalone solar photovoltaic system with hybrid energy storage

Energy storage devices and renewable resources, especially rooftop photovoltaic (PV), are vital to the operation of standalone systems. In this study, an energy management strategy (EMS) for battery energy storage systems (BESS), PV, and supercapacitors (SC) is presented. The proposed control strategy is designed to optimize the BESS flow rate, discharge, and charge cycles of the energy system using the Meta-heuristic Jaya algorithm by properly coordinating SC and PV. SC is employed in HESS to fulfill the transient energy mismatches and reduce the transitory high charge/discharge current rate impacts on BESS using EMS. The proposed controller also has the benefit of keeping the battery's SoC within limitations for a long period. To extend the life of BESS, the EMS is aimed at minimizing deep charging and discharging by reducing PV generation, particularly under light load (no-load) situations and when battery and SC's SoC≥SoCmax or charging. Similarly, the optional load shedding is employed when battery and SC's SoC≤SoCmin to avoid deep discharge. The proposed EMS is validated in both simulation environment and hardware-prototype under different perturbations and operating conditions. The charge and discharge rate performance of BESS and SC under different charge and discharge time durations, i.e., 1 s, 2 s, and 3 s, were evaluated in both simulation and hardware, and compared to conventional charge and discharge methods for HESS, whose charge and discharge time durations are nearly 0.3 s to 0.4 s. As a result, battery stress is significantly reduced. Furthermore, the economic analysis of the complete system is carried out. In this, it is observed that standalone PV and HESS systems with the proposed EMS are cost-effective and economical compared with PV and BESS systems when operated for a long horizon beyond 6 years.