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Abstract This paper contributes to the existing literature as well as policy debates by examining energy intensity and its determinants in China's regional economies. The analysis is based on a comprehensive database of China's regional energy balance constructed for this project. Through its focus on regional China, this study extends the existing literature, which mainly covers nationwide studies. It is found in this paper that energy intensity declined substantially in China. The main contributing factor is the improvement in energy efficiency. Changes in the economic structure have so far affected energy intensity modestly. Thus there is considerable scope to reduce energy intensity through the structural transformation of the Chinese economy in the future.

This paper proposes an improved L index which is adapted to analyze the voltage stability of power system with the ZIP loads. First it introduces derivation of the traditional L index. Then, it analyzes the differences between ZIP loads and PQ loads and then proposes an improved version of L index based on the derivation. Furthermore, the proposed improved index is used to analyze the voltage stability under different operation conditions of the power system with ZIP loads. The simulations show the effectiveness of the proposed improved L index.

AbstractAlloy anodes composed of microsized particles receive increasing attention recently, which outperform the nanostructured counterparts in both the manufacturing cost and volumetric energy density. However, the pulverization of particles and fracture of solid electrolyte interphase (SEI) during cycling brings about fast capacity degradation. Herein, it is shown how normally considered fragile SEI can become highly elastic through electrolyte chemistry regulation. Compared to the SEI constructed in classic carbonate electrolyte, the atomic force microscopy tests reveal that the one built in ether‐based electrolyte doubles the maximum elastic strain to accommodate the repeated swelling‐contracting. Such an SEI effectively encapsulates the microsized Sb anodes to prevent the capacity loss from particle isolation. Coupled with an intercalation‐assisted alloying reaction mechanism, a sustained capacity of ≈573 mAh g−1 after 180 cycles at 0.1 A g−1 with outstanding initial Coulombic efficiency is obtained, which is among the highest values achieved in K‐ion batteries. This study emphasizes the significance of building robust SEI, which offers the opportunity to enable stable microsized alloy anodes.

Abstract Accurate power forecasting is of great importance to the turbine control and predictive maintenance. However, traditional physics models and statistical models can no longer meet the needs of precision and flexibility when thermal power plants frequently undertake more and more peak and frequency modulation tasks. In this study, the recurrent neural network (RNN) and convolutional neural network (CNN) for power prediction are proposed, and are applied to predict real-time power of turbine based on DCS data (recorded for 719 days) from a power plant. In addition, the performances of two deep learning models and five typical machine learning models are compared, including prediction deviation, variance and time cost. It is found that deep learning models outperform other shallow models and RNN model performs best in balancing the accuracy-efficient trade-off for power prediction (the relative prediction error of 99.76% samples is less than 1% in all load range for test 216 days). Moreover, the influence of training size and input time-steps on the performance of RNN model is also explored. The model can achieve remarkable performance by learning only 30% samples (about 216 days) with 3 input time-steps (about 60 s). Those results of the proposed models based on deep-learning methods indicated that deep learning is of great help to improve the accuracy of turbine power prediction. It is therefore convinced that those models have a high potential for turbine control and predictable maintenance in actual industrial scenarios.

In this paper, a comparison of power system frequency response is conducted for a simple modelled power system with primary frequency control being provided either by synchronous generators or by inverter-based Battery Energy Storage (BES) systems. Mathematical models of conventional governor and turbine are developed, representing conventional synchronous generator frequency control, and are used to illustrate system frequency response for a range of typical conventional generating units. A mathematical model of a power-electronics interfaced Li-ion BES system is developed and used to represent a non-synchronous inverter-based generator with primary frequency control capabilities. MATLAB/Simulink is used to build a model of a small power system, and simulations are carried out with at a range of typical conventional synchronous generating units with a nonsynchronous generating unit in the power system. The simulation results demonstrate that the BES can be used for primary frequency control providing a faster and better response. BES is also capable of almost eliminating frequency overshoot and reducing 70% of settling time while providing primary frequency control in power system with various types of conventional synchronous generating units and a nonsynchronous generating unit.

Abstract To improve the conversion efficiency of thermophotovoltaic devices, we designed a thermophotovoltaic system based on an InAs/InGaAsSb/GaSb three-junction tandem cell. The tandem cell can recover photons in the wavelength range of 200–3650 nm and therefore enhance the output power of the system. To further improve system performance, we designed a multilayer circular truncated cone metamaterial emitter matching the tandem cell. Existing TPV systems based on multi-junction tandem PV cells can achieve conversion efficiencies of 33.3%–41%, while the thermophotovoltaic system coupled with the multilayer circular truncated cone metamaterial can recover more photons of 1.44 mol/(m2·s) and achieve a higher conversion efficiency of 52.8% at 1773 K. The thermophotovoltaic system designed here demonstrates an extremely high energy conversion efficiency and has good application prospects.

This paper proposes a sustainability-oriented multiobjective optimization model for siting and sizing DG plants in distribution systems. Life cycle exergy (LCE) is used as a unified indicator of the entire system’s environmental sustainability, and it is optimized as an objective function in the model. Other two objective functions include economic cost and expected power loss. Chance constraints are used to control the operation risks caused by the uncertain power loads and renewable energies. A semilinearized simulation method is proposed and combined with the Latin hypercube sampling (LHS) method to improve the efficiency of probabilistic load flow (PLF) analysis which is repeatedly performed to verify the chance constraints. A numerical study based on the modified IEEE 33-node system is performed to verify the proposed method. Numerical results show that the proposed semilinearized simulation method reduces about 93.3% of the calculation time of PLF analysis and guarantees satisfying accuracy. The results also indicate that benefits for environmental sustainability of using DG plants can be effectively reflected by the proposed model which helps the planner to make rational decision towards sustainable development of the distribution system.

The dynamic behaviors of a proton exchange membrane (PEM) fuel cell have been studied both experimentally and numerically. The objective of this paper is to investigate the effects of cathode inlet humidification on PEM fuel cell load change operations and the fuel cell performance during a simulated start-up process. The PEM fuel cell was found to respond quickly and reproducibly to load changes. It was also found that an increase in the cathode inlet humidification significantly influences the start-up performance of a PEM fuel cell. The cathode inlet relative humidity (RH) under 30% significantly dropped the cell dynamic performance. Extensive numerical simulations, with the transient processes of load jump and gradual changes considered, were performed to characterize dynamic responses of a singe-channel PEM fuel cell under different inlet humidification levels. The results showed that the response time for a fuel cell to reach steady state depends on water accumulation in the membrane, which is consistent with the experimental results. Copyright © 2010 John Wiley & Sons, Ltd.

Funding Information: This work was supported Southeast University (SEU) project 3203002003A1 and National Natural Science Foundation of China (NSFC) under the grant 51772080 and 11604088 . Jiangsu Provincial Innovation and Entrepreneurship Talent program Project No. JSSCRC2021491 . Industry-University-Research Cooperation Project of Jiangsu Province in China , Grant No. BY2021057 . Dr. Asghar thanks the Hubei Talent 100 program and Academy of Finland ( 13329016 , 13322738 ) for their financial support. Publisher Copyright: © 2022 The Authors Electrolytes with high-proton conduction and low activation energy are attractive for reducing the high operating temperature of solid-oxide fuel cells to less than <600 °C. In this work, we have fabricated semiconducting electrolyte SrFeTiO3-δ (SFT) material exhibiting high ionic conduction and exceptionally high protonic conduction at low operating temperature but with low electronic conduction to evade the short-circuiting issue. The prepared fuel cell device exhibited high open-circuit voltage (OCV) and a high-power output of 534 mW/cm2, of which 474 mW/cm2 could be for sure be related to the protonic part. The current study suggests that usage of semiconductor SrFeTiO3-δ facilitates a high concentration of oxygen vacancies on the surface of SFT, which mainly benefits proton conduction. Moreover, lower grain boundary resistance leads to obtain higher performance. Also, the Schottky junction phenomena are proposed to inhibit the e-conduction and excel the ions transportation. The high performance and ionic conductivity suggest that SFT could be a promising electrolyte for protonic ceramic fuel cells. Peer reviewed