Dielectric materials with high power density, fast charge and discharge rates, and high energy-storage density are urgently required due to the rapid development of hybrid vehicles and pulse power ...boosting technology. In this work, the novel environment-friendly (1-x)(Ba0.8Sr0.2)TiO3-xBi(Zn2/3Nb1/3)O3 (0.04 ≤ x ≤ 0.16) (1-x)BST-xBZN ceramics were designed and synthesized by traditional solid-state reaction method, exhibiting ultrahigh energy efficiency and super stability against temperature. The results show that the recoverable energy density (Wrec) and the energy efficiency (η) of the (1-x)BST-xBZN ceramics are increase sharply then decrease slightly with increasing of x value. The 0.88BST-0.12BZN ceramic demonstrated a recoverable energy density of ≈ 1.62 J/cm3 and an extreme high energy efficiency of ∼ 99.8 % at 225 kV/cm at room temperature. These extreme high efficiency and high breakdown strength would make (Ba,Sr)TiO3-based lead-free ceramic systems might be good candidate for high power energy-storage applications pulsed power systems.
Despite strong political efforts in Europe, industrial small- and medium-sized enterprises (SMEs) seem to neglect adopting practices for energy efficiency. By taking a cultural perspective, this ...study investigated what drives the establishment of energy efficiency and corresponding practices in SMEs. Based on 10 ethnographic case studies and a quantitative survey among 500 manufacturing SMEs, the results indicate the importance of everyday employee behavior in achieving energy savings. The studied enterprises value behavior-related measures as similarly important as technical measures. Raising awareness for energy issues within the organization, therefore, constitutes an essential leadership task that is oftentimes perceived as challenging and frustrating. It was concluded that the embedding of energy efficiency in corporate strategy, the use of a broad spectrum of different practices, and the empowerment and involvement of employees serve as major drivers in establishing energy efficiency within SMEs. Moreover, the findings reveal institutional influences on shaping the meanings of energy efficiency for the SMEs by raising attention for energy efficiency in the enterprises and making energy efficiency decisions more likely. The main contribution of the paper is to offer an alternative perspective on energy efficiency in SMEs beyond the mere adoption of energy-efficient technology.
The traditional estimation methods tend to result in biased energy efficiency estimates due to the exclusion of heterogeneous production technology. Taking this factor into account, this study uses ...the metafrontier method combined with the stochastic frontier analysis (SFA) to analyze energy efficiency performance of the industrial sectors in China’s 30 provinces during 1997–2016. This study measures energy efficiency by considering the technological gap that can be regarded as a discrete source of energy inefficiency. Different from the traditional classification of different regions in China, we divide regions into three groups by using the cluster analysis based on the indicator of energy intensity. The empirical results are summarized as follows: first, the traditional pooled estimation method, which ignores the technological gap of the industrial sectors among different regions, tends to overestimate energy efficiency performance; second, energy efficiency and technological gap ratios (TGRs) of the industrial sectors are distinct among China’s regions; and the industrial sectors of the eastern region maintained higher energy efficiency and TGRs due to more advanced production technology; third, in general, the average score of industrial energy efficiency of China was only 0.4396, implying that there’s still plenty of room for energy efficiency improvement.
•Applying SFA method with metafrontier to analyze industrial energy efficiency.•Considering technological heterogeneity in energy efficiency measurement.•The traditional pooled estimation tends to overestimate energy efficiency.•Regional differences exist in industrial energy efficiency and TGRs.
Considering the flexibility and adjustability value of integrated energy system (IES) with flexible energy units and multivariate adjustable load in urban energy market, this paper proposes a ...two-stage energy management method of heat-electricity integrated energy system (HE-IES) considering dynamic pricing of Stackelberg game and operation strategy optimization. Firstly, a general comprehensive energy efficiency considering the exergy properties of electric and thermal energy is established, on this basis, this paper put forward a two-stage energy management framework considering interactive relationship between energy service provider (ESP) and users. Secondly, a two-stage energy management model is established to improve the energy efficiency and operation economy of the system, which includes the multi-objective optimization model of day-ahead scheduling and Stackelberg game dynamic pricing model of real-time energy management based on the source-load interaction optimization for hybrid energy. Finally, in order to illustrate the effectiveness of the proposed energy management method in improving system energy efficiency and operation strategy, a typical HE-IES consisting of 6 users and 1 ESP is chosen to simulation. The simulation results demonstrate that the proposed approach can not only enhance renewable energy utilization and reduce the cost of both ESP and users, but helpful to promote the benign interaction between energy equipment and load in IES, which could improve the energy efficiency of system operation.
•The Hybrid energy conversion framework of integrated energy system is established.•A two-stage energy management model is constructed.•In the first stage, IES operation optimization based on economy and energy efficiency is implemented.•In the second stage, optimization strategy of users participating in game optimization guided by ESP is implemented.
•A basic and comprehensive picture of research on occupant behavior and building energy performance is presented by systematic review of the literature.•Four critical research topics are ...identified.•Energy-saving potential of occupant behavior is discussed and estimated to be in the range of 10%−25% for residential buildings and 5%−30% for commercial buildings.•Four existing research gaps are identified and discussed.
Technology alone will not achieve building energy conservation goals, and humans and their energy-related behavior in buildings must be included in energy performance efforts. Despite many studies revolving around human behavior and building energy performance, the understanding of occupant behavior and its role in building energy performance remains vague, confusing and inconsistent. We attempt to rethink occupant behavior and its role in building energy performance by means of review. Relevant articles have been collected from Web of Science and the basic picture of research has been presented. In-depth review focuses on four critical research topics: a) the current understanding of occupant behavior, with particular focus on window opening behavior, lighting control behavior, and space heating/cooling behavior; b) methods and techniques for collecting data on behavior and building energy performance; c) quantitative modeling of occupant behavior and building energy performance; and d) evaluation of energy saving potentials of occupant behavior based on existing literature. We estimate the energy-saving potential of occupant behavior to be in the range of 10%–25% for residential buildings and 5%–30% for commercial buildings, based on findings of existing research. From our analyses, we identify four existing research gaps, namely the needs for understanding occupant behavior in a systematic framework; for stronger empirical evidence beyond individual buildings and at a larger city scale; for linking occupant behavior to socio-economic and policy variables; and for evaluating the role of occupant behavior in the effectiveness of building energy efficiency policy.
The combination of simultaneous wireless information and power transfer (SWIPT) and non-orthogonal multiple access (NOMA) is a potential solution to improve spectral efficiency and energy efficiency ...(EE) of the upcoming fifth generation (5G) networks, especially in order to support the functionality of the Internet of things (IoT) and the massive machine-type communications (mMTC) scenarios. In this paper, we investigate joint power allocation and time switching (TS) control for EE optimization in a TS-based SWIPT NOMA system. Our aim is to optimize the EE of the system whilst satisfying the constraints on maximum transmit power budget, minimum data rate, and minimum harvested energy per terminal. The considered EE optimization problem is neither linear nor convex involving joint optimization of power allocation and time switching factors and, thus, is extremely difficult to solve directly. In order to tackle this problem, we develop a dual-layer algorithm where Dinkelbach method is employed both in the inner layer to optimize the power allocation and in the outer layer to control the time switching assignment. Furthermore, a simplified but practical special case with equal time switching factors in all terminals is considered. Numerical results validate the theoretical findings and demonstrate that significant performance gain over orthogonal multiple access scheme in terms of EE can be achieved by the proposed algorithms in a SWIPT-enabled NOMA system.
A method for automatic "maximum energy efficiency tracking" operation for wireless power transfer (WPT) systems is presented in this paper. Using the switched-mode converter in the receiver module to ...emulate the optimal load value, the proposed method follows the maximum energy efficiency operating points of a WPT system by searching for the minimum input power operating point for a given output power. Because the searching process is carried out on the transmitter side, the proposal does not require any wireless communication feedback from the receiver side. The control scheme has been successfully demonstrated in a two-coil system under both weak and strong magnetic coupling conditions. Experimental results are included to confirm its feasibility.
Financial risk mitigation via Energy Performance Contracting or Energy Efficiency Insurances may overcome individual barriers for energy efficiency investments. However, while the financial industry, ...and especially insurance companies, may have compelling reasons to get involved in energy efficiency investments, the research on and real-world applications of risk transfer contracts for private decision-makers are scarce. Thus, this study quantitatively compares the risk mitigation potential of risk transfer contracts based on a comprehensive energy bill savings forecast model comprising stochastic processes for weather, commodity prices, and technological energy efficiency performance. The model is fitted with a unique dataset for German residential buildings. Our findings indicate that risk transfer contracts positively affect individual decision-makers' willingness to invest in energy efficiency. Generally, we find Energy Performance Contracts to be superior in most scenarios when transaction costs are not considered. However, insurance companies may benefit from diversification effects and by ceding risks to global capital markets and reinsurance companies.
•Quantitative comparison of risk mitigation potential of risk transfer contracts•Introduction of energy bill savings forecast model based on real-world data•Risk transfer contracts positively affect private energy efficiency investments•Energy Savings Guarantee is superior to insurances based on fair premiums.•Energy Efficiency Insurances could be superior when transaction costs are reduced.
This paper is to review what kinds of mathematical methods used in developing benchmarking systems, to discuss the properties of the methods, and to classify two kinds of benchmarking systems based ...on their properties. We find that while benchmarking systems are developed by using the energy-use performance of a significant number of reference buildings, benchmarking results can be used to encourage poor reference performers (in energy-efficiency) to improve their performance. On the other hand, because benchmarking systems also function as a public yardstick of energy-use performance in buildings, some regulators release benchmarking information to the media. This proves advantageous because it brings public pressure on owners/developers of poorly performing non-reference buildings. However, not all benchmarking systems can be used by public users (i.e., other non-reference building owners). Depending on whether the resulting benchmarking system can be used in public, we note that there are two kinds of benchmarking system: public benchmarking and internal benchmarking. These two types of benchmarking system are developed by different methods.
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