Energy-efficient Applications Research Articles

Simultaneous enhancement of recoverable energy density and efficiency of lead-free relaxor-ferroelectric BNT-based ceramics

Given the remarkable performances of Ruddlesden-Popper (RP) type oxides in electronic devices, the study of their intrinsic dielectric, magnetic and electromagnetic microwave (EMW) absorption properties are still missing. Herein, two kinds of Lead-free relaxor-ferroelectric BNT-based ceramic hierarchical polycrystalline alloys (La3Ni2O7/LaNiO3, La2NiO4/La2O3) were prepared via a facile solvothermal and high-temperature annealing technique as high-performance EMW absorption materials (MAMs). By a means of adjustment of solvothermal time in the precursor systems, Nickel salt layers precipitation declined gradually. The phase and crystal state of the powders were characterized by X-ray diffraction (XRD) with refinement treatment (Rietveld analysis). XPS was utilized on the determination of interstitial O2– quantitatively in La3Ni2O7+δ (δ = 1.95) and La2NiO4+δ (δ = 0.75). Responsible to the synergistic effect of dielectric and magnetic response and well-matched impedance, the as-fabricated MAMs performed excellent wave absorbability, especially in low frequency (S-band). In details, La3Ni2O7/LaNiO3 achieved optimal effective absorption band (fE) 3.36 GHz at 9.52–12.80 GHz and a minimum reflection loss (RLmin) −43.30 dB with a thickness of 2.2 mm. Moreover, La3Ni2O7/LaNiO3 and La2NiO4/La2O3 overcame the challenge of absorbers’ thickness in S-band, of which the RL reached –22.63 and −29.90 dB at 0.7 mm, respectively. Noteworthily, La3Ni2O7/LaNiO3 obtained RL value of −50.06 dB at 10.72 GHz with a device thickness of 2.8 mm. It is emphasized that this report has interpreted the EMW absorption capacity and mechanism exhaustively, which will initiate simultaneous enhancement of recoverable energy density and efficiency application of RPs.

A Comparative Study on Turkey s National Green Building Certification System Under Energy Policy Developments

In today’s living conditions, the quality of life depends on well-managed energy. Therefore, countries produce different energy policies to manage their energy resources. Determining appropriate, feasible, and controllable energy policies becomes important especially for buildings, as being one of the most significant energy consumers. Green building certification systems (GBCSs) are one of the most common applications for energy efficiency in the building sector. Purpose This paper is a comparative analysis of GBCSs in developed and developing countries, in an effort to establish the similarities and differences between Turkey’s first national GBCS – B.E.S.T and other GBCSs, and to determine how the energy criteria in GBCSs contribute to each dimension of sustainability (i.e., environmental, economic, social). Design/Methodology/Approach The research methodology depends on the literature review and documentary review on energy-related regulations, legislation, and laws. A comparative analysis of GBCSs was conducted in the study. Not only the sub-criteria directly exist under the energy criterion, but also indirect energy criteria, which are included in the sub-criteria of all other criteria within the GBCS, were numerically evaluated with the helped of developed matrix. Findings The results show that energy credits were given the highest weight by LEED (~33%) in international GBCSs and by GRIHA (~42%) in national GBCSs. In B.E.S.T, this is ~29%. It was determined that B.E.S.T was structurally similar to LEED, while it was similar to BREEAM in terms of weight and importance given to the energy criteria. According to the developing country GBCSs, the biggest similarity is seen with GBI. In terms of SD, it is found that GBCSs present similar characteristics to their regional development level. Where a GBCS serves for a developing region, the main concerns of energy criteria focus on the intersection of its environmental and economic aspects. Thus, B.E.S.T has been created in a similar structure and the highest share (%80) on environmental-economic aspects. Research Limitations In the study, the comparison was made between selected international GBCSs like BREEAM, LEED, and DGNB and national GBCSs like GM, GBI, and GRIHA. Practical Implications In practice, the results can help owners or developers to focus on which energy criteria contribute economic, social or environmental advantage for them. Social Implications This study also provides some recommendations for further application and academic studies of B.E.S.T. Originality/Value Increasing the recognition of Turkey’s national GBCS in scientific researches and contributing to the development of it have made this study original and unique.

Switching at Less Than 60 mV/Decade with a “Cold” Metal as the Injection Source

Power dissipation is a great challenge for the continuous scaling down and performance improvement of CMOS technology, due to thermionic current switching limit of conventional MOSFETs. In this work, we show that this problem can be overcome by using cold metals as the transistor's injection source, which are different from conventional metals and can filter high energy electrons to break the Boltzmann tyranny. It is proved that the subthreshold swing (SS) of thermionic current of transistor using cold metal contact can be extremely smaller than 60 mV/decade at room temperature. Specifically, two-dimensional (2D) transition metal chalcogenide (TMD) cold metals of NbX$_2$ and TaX$_2$(X=S, Se, Te) are proposed as the injection source of FETs. Quantum transport simulations indicate that promising switching efficiency and on-state current can be achieved using TMD cold metal injection source, which is beneficial for energy efficient applications.

A Micro-Moment System for Domestic Energy Efficiency Analysis

Domestic user behavior is a crucial factor guiding overall power consumption, necessitating the development of systems that analyze and help shape energy-efficient behavior. Therefore, the most important step in the process is the collection and understanding of highly detailed domestic consumption data. This article presents an appliance-based energy data collection and analysis system for energy efficiency applications. It leverages the concept of micro-moments, which are short-timed and energy-based events that form the overall energy behavior of the end user. The system comprises sensing modules for recording energy consumption, occupancy, temperature, humidity, and luminosity storing recordings on a database server. Sensing parameters were tested in terms of connection stability and measurement accuracy. A four-week contextual appliance-level dataset has been collected from research cubicles. Collected data were also classified into corresponding micro-moments with a variety of classifiers including ensemble decision trees and deep learning, achieving high stability and accuracy of 99%. Further, the micro-moment usage efficiency is calculated to quantify the efficiency of usage at the appliance level.

Non-thermal resistive switching in Mott insulator nanowires

Resistive switching can be achieved in a Mott insulator by applying current/voltage, which triggers an insulator-metal transition (IMT). This phenomenon is key for understanding IMT physics and developing novel memory elements and brain-inspired technology. Despite this, the roles of electric field and Joule heating in the switching process remain controversial. Using nanowires of two archetypal Mott insulators—VO2 and V2O3 we unequivocally show that a purely non-thermal electrical IMT can occur in both materials. The mechanism behind this effect is identified as field-assisted carrier generation leading to a doping driven IMT. This effect can be controlled by similar means in both VO2 and V2O3, suggesting that the proposed mechanism is generally applicable to Mott insulators. The energy consumption associated with the non-thermal IMT is extremely low, rivaling that of state-of-the-art electronics and biological neurons. These findings pave the way towards highly energy-efficient applications of Mott insulators.

Application of scenario analysis for assessing the environmental impacts of thermal energy substitution and electrical energy efficiency in clinker production by life cycle approach

In this work, a life cycle approach is used to evaluate the potential environmental impacts of thermal energy substitution and electrical energy efficiency applications in clinker production, which is a highly energy-intensive process. Sixteen scenarios are designed in addition to a business-as-usual (BAU) scenario by considering two approaches: (1) eight scenarios that feature different types (dried sludge [DS], refuse-derived fuel [RDF], and residual oil) and substitution rates (15% and 30% of thermal energy) of alternative fuels and (2) eight scenarios that consider the projected electricity consumption and electricity generation mix for 2023 in Turkey. A cradle-to-gate life cycle assessment (LCA) is conducted, including raw material acquisition from nature, transportation of all materials to a cement plant, raw material preparation, raw meal milling, and kiln burning. The life cycle impacts are assessed with the IMPACT 2002+ method, including both the midpoint and endpoint approaches. As the substitution rate of dried sludge and RDF is increased from 15% to 30%, all midpoint impacts are improved except respiratory inorganics because of the additional electricity usage of the pretreatment processes of those waste fuels before incineration in cement kiln. Reducing the specific amount of electricity consumption and the preferred electrical energy produced through renewable sources in clinker production is a more suitable option compared with the thermal energy substitution scenarios. In terms of overall environmental burden, Scenario 6E, which uses RDF with a thermal substitution rate of 30%, is the most environmentally friendly option among the 16 scenarios. On the contrary, Scenario 5, which uses dried sludge with a thermal substitution rate of 30%, is the worst option.

Designing ultra-strong nanocrystalline Cu–Me (Me = Mg, Al) thin films: Manipulation of nanotwin patterns

How to design ultra-strong solid solution-type Cu alloys is a long-term pursuit in materials community, which is technically superior and cost-effective for their promising energy efficient applications. In this work, we prepared Cu–Me (Me = Mg, Al) alloyed thin films via non-equilibrium magnetron sputtering disposition to study light element Me alloying effects on the microstructure and mechanical properties of nanocrystalline (NC) Cu thin films. In the studied solute Me content-range spanning from 1.0 at% to 17.0 at%, Mg alloying renders a peak number fraction (~80%) of columnar(-like) grains with only containing single nanotwins, while Al alloying renders monotonically increased fraction (to ~55%) of columnar grains with containing single and/or multiple-fold twins. Compared with single nanotwins, multiple-fold twins can more significantly enhance the hardness of NC Cu–Al alloys. A combined strengthening model was employed to quantify the Me concentration-dependent hardness of NC Cu–Me thin films, which can reach at least about twice that of NC Cu matrix (~1.8 GPa). Importantly, the present NC Cu–Me alloys with nanotwinned microstructure manifest excellent specific strength compared with reported Cu alloys. These findings convey the valuable information for designing ultra-strong NC Cu-based alloys by tuning internal morphologies of nanotwins, e.g. penta-twins and parallelogram twins.

Application of the Second Law of Thermodynamics in Brazilian Residential Appliances towards a Rational Use of Energy.

This article proposes the utilization of the concepts of destroyed exergy and exergy efficiency for equipment and process performance indicators that are related to the current energy planning scenario in Brazil, more specifically with energy-efficiency labelling. Several indicators associated with these concepts are discussed, including one national program that is based on labeling the energy efficiency of several residential, commercial and industrial appliances. The grades are indicated in the equipment using values from A to G. This labeling system is useful for discriminating similar technologies used for the same function; nevertheless produced by different enterprises. For this complementary analysis, two types of refrigeration methods were compared, absorption and vapor compression; however, these energy indexes alone are not sufficient parameters to select among these two technologies, because their performance indexes definition are different. To address this, our research considers the second law of thermodynamics through exergy analysis as a proper sub-index to obtain a systematic comparison between these various indicators. It is significant to highlight that seldom research studies addressed to this problem so explicitly, in an actual governmental working solution, aiming at discussing to the society the advantage of the usage of the “quality of the energy” as a complementary index to governmental and personal choices. Results indicate that it is possible to use the destroyed exergy and exergy efficiency to help select the technology that better utilizes natural resources, considering the energy matrix of the country. Appliances for water heating and air conditioning were compared from energy and exergy viewpoint, where the last gave additional information about the quality of energy conversion process, giving a completely different trend from the energy analysis alone, without the necessity to think about the energy matrix. Later this issue is addressed from both points of view. Future studies may suggest an exergy based index. The energy efficiency suggests that electrical shower (values higher than 95%) are better than gas water heaters (83%) in using natural resources, whereas the exergy efficiency shares similar magnitudes (about 3%). A related pattern is shown for the theoretical air conditioning systems. The vapor compression systems have an energy index higher than 3, and absorption systems lower than 1. For these circumstances, the exergy efficiency shows figures nearby 30%.

Water and Metal-Organic Frameworks: From Interaction toward Utilization.

The steep stepwise uptake of water vapor and easy release at low relative pressures and moderate temperatures together with high working capacities make metal–organic frameworks (MOFs) attractive, promising materials for energy efficient applications in adsorption devices for humidity control (evaporation and condensation processes) and heat reallocation (heating and cooling) by utilizing water as benign sorptive and low-grade renewable or waste heat. Emerging MOF-based process applications covered are desiccation, heat pumps/chillers, water harvesting, air conditioning, and desalination. Governing parameters of the intrinsic sorption properties and stability under humid conditions and cyclic operation are identified. Transport of mass and heat in MOF structures, at least as important, is still an underexposed topic. Essential engineering elements of operation and implementation are presented. An update on stability of MOFs in water vapor and liquid systems is provided, and a suite of 18 MOFs are identified for selective use in heat pumps and chillers, while several can be used for air conditioning, water harvesting, and desalination. Most applications with MOFs are still in an exploratory state. An outlook is given for further R&D to realize these applications, providing essential kinetic parameters, performing smart engineering in the design of systems, and conceptual process designs to benchmark them against existing technologies. A concerted effort bridging chemistry, materials science, and engineering is required.

Coverage aware face topology structure for wireless sensor network applications

Providing effective sensing coverage of an observation area with reduced set of working nodes for maximum duration of time is an important concern for the development of durable and energy efficient WSN applications. A well-organized network structure can greatly promote such requirements. Motivated by the use of computational geometry in network design, we propose a coverage-aware and efficient planar face topology structure (CAFT) for WSN in this paper. Also, a distributed target tracking algorithm is proposed to run on the proposed face structure. Most of the existing works utilize the face based WSNs which are built by generating planarized graphs using Gabriel graph or Relative neighborhood graph in which all the deployed nodes become a part of the created toplogy. In contrast to this, our proposed distributed topology construction method selects and organizes a subset of nodes into faces, ensures coverage and connectivity while retaining the remaining nodes in sleep mode which can reduce redundant communication that may result in extra energy consumption and cost. The sleep nodes can promote durable service time for the WSN as such nodes can act as replacement nodes in case of node faults and failures, reducing coverage hole formation in the WSN, which is crucial in critical tracking applications. The simulation results and comparison with existing techniques prove that the proposed design is effective in reducing the energy consumption and thereby improves the WSN lifetime.

Tuning the on/off current ratio in ionic-liquid gated multi-layer MoS2 field-effect transistors

Ionic-liquid gated multi-layer MoS2 field-effect transistors were fabricated and their electrical properties related to maximum depletion depth, bulk neutral and surface accumulation conduction were investigated in detail. A negative back-gate bias resulted in a depletion of the bulk neutral channel at the bottom interface, which significantly enhanced transistor performance in terms of the on-current to off-current (Ion/Ioff) ratio and the off-state current level. The experimental results were verified by numerical simulations and analytical equations. These findings are critical for the optimization of the Ion/Ioff ratio of multi-layer MoS2 transistors for energy efficient electronics and low power applications.

Energy efficiency analyses in a Turkish fabric dyeing factory

ABSTRACT In this study, energy efficiency applications and corresponding energy saving results were evaluated in a Turkish fabric dyeing factory. The relationship between energy consumption and the production were evaluated by regression analysis. They were detailed with energy intensity index (EII), cumulative sum values (CUSUM), specific energy consumption (SEC), and radar chart. The energy efficiency efforts should be initiated from heat and electrical energy, which are the main energy types extensively used in the textile industry. Average energy consumption value of the last four years (2015–2018), which is 7134 TOE is reduced 49% including waste heat, flash steam and cooling water recovery, and insulation in dyeing machines, in the factory due to the implementation of the energy saving actions. Accordingly, a reduction of 25% SEC value is possible. Moreover, production planning has a significant impact on the total energy consumption in terms of full load capacity operation of the dyeing machines, which may cause 23% energy saving that is of great importance.

An application of total-factor energy efficiency under the metafrontier framework

As the computation of total-factor energy efficiency (TFEE) is not workable under the metafrontier framework since the metafrontier cannot fully envelope each group frontier, this research provides a new computation mode to solve this problem. Following a discussion on the methodology, we conduct empirical analysis on 28 member countries in the European Union (EU) and then divide them into Baltic sea region (BSR) countries and non-Baltic sea region (NBSR) countries for metafrontier analysis, thus contributing to the literature by presenting an available mode for TFEE analysis under the metafrontier framework. The suggested mode herein operates so successfully that all computation scores exhibit a reasonable scope. In addition, the BSR's average energy efficiency performs better than NBSR's, but the latter is still a technology exporter compared to the former. This paper summarizes the conditions for sustainable energy development: (i) set more serious energy efficiency targets; (ii) reduce primary and final energy consumptions, lower energy dependence on energy imports, and increase the share of renewable energy sources to fossil fuel energy sources; (iii) achieve a liberalized energy market; and (iv) set reasonable energy prices by levying an energy tax in order to realize effective energy consumption.

Mathematical Modeling of a Linear Motion on a Deformable Bearing Surface of a Saddle-Type Road Train with Active Semi-Trailer Element

The paper introduces a mathematical modeling of linear motion on a deformable bearing surface (DBS) of a two-link road train consisting of four-axle truck with independent wheel drive and a three-axle semi-trailer. Predictive modeling based on application of pull-traction and energy efficiency obtained during the field research was used in the course of the model development to predict wheeled vehicle mover properties. Results of the theoretical research are given that relates to road train uphill motion with various wheel drives of the semi-trailer.

Dimensionless exergo-economic and emission parameters for biogas fueled gas turbine optimization

Optimization of energy system is a favored method to mitigate emission and manage fuel resources. However, optimization results interpretation and optimal point selection is a challenging area, and mostly a subjective decision. In addition, optimization, even with cost objectives, are carried out by technical teams which normally differ from project decision makers. To provide a solution, at first a framework for optimization is defined with general optimal correlations as goals of optimization. This framework is devised to prepare results understandable and helpful to decision makers. Then two important parameters named cr (ratio of product to fuel cost) and CR (ratio of annualized fixed to current cost) are employed to represent the system performance and design variables in optimal points of pareto front. Finally, a set of correlation functions is evaluated to correlate the optimal design variables to design parameters. In addition, an emission parameter is introduced in terms of cr and CR. The results revealed that cr-CR can successfully represent the system characteristics and lead to smooth functionality between newly defined star design variables and cr. The method is implemented on a biogas fueled gas turbine. Sensitivity of minimum cr to fuel composition variations is examined and results illustrate that at this point, implementing 50% methane content for a system which is designed optimally for pure methane, causes 2% reduction in efficiency and increases the cost of product. However, in comparison to system optimally designed for 50% methane, efficiency drop is less than 1% and product cost does not change significantly. Analyzing ep (emission per product) and cr suggests that CR < 0.8 is suitable for optimal design selection. The proposed method here helps to tradeoff between cost and emission reduction in early phase of the project which boost energy efficiency applications.

An assessment of energy efficient motors application by scenarios evaluation

The choice of the most appropriate public policies to foster energy efficiency measures often is a difficult task due to the large number of intervening variables and agents and, also, high levels of uncertainties in estimating the corresponding energy savings. This paper presents a methodology that builds up scenarios to assess the impacts on energy consumption of introducing different levels of penetration of efficient electric induction motors, according to the set of policies and measures adopted in the scenarios. The proposed methodology comprises three modules. The first one selects strategic objectives, key variables and control players, determines their direct and cross-influence levels, based on the opinions of consulted experts, and sets up some scenarios combining them. The second module carries out electric motor sales forecasts based on electricity consumption forecasts for the industry. The third module estimates the energy saving forecasts associated to each scenario. The approach is applied to Brazil in the paper, indicating valuable policy options and their likelihood to local decision makers and other stakeholders.

Urban consumers’ willingness to pay for higher-level energy-saving appliances: Focusing on a less developed region

Rapid urbanization poses accelerating pressure on energy and resources consumption, especially in the less developed regions. The Energy Efficiency Labeling System (EELS) reporting the energy efficiency of various household appliances has been implemented aiming at reducing household energy consumption. It has been proved useful in guiding consumers to purchase higher-level energy-saving appliances (ESAs). In this study, we attempt to explore how much urban consumers are willing to pay additionally for higher-level ESAs compared with the lower-level ones in a typical less developed region in China (Jilin Province). The Contingent Valuation Method (CVM) is adopted to measure the influencing factors of the willingness to pay (WTP). It is found that the consumers are willing to pay additionally 12.31% and 33.43% of the price of level-3 ESAs for level-2 and level-1 ESAs, respectively (there are five levels in total among which level-1 is the highest). Age, education background, environmental consciousness and other factors have different degrees of effects on the WTP, among which annual household income is the most influential one. The female with full-time housework, the young with good environmental consciousness, those with master degree or the above, and government staff with high recognition of the EELS tend to purchase the highest-level ESAs. This study is expected to provide insights for policy interventions aimed at advocating the use of higher-level ESAs and reducing household energy consumption.

DSM interactions: What is the impact of appliance energy efficiency measures on the demand response (peak load management)?

Abstract: To date, research has mostly focused on the impact of energy efficiency on the total electricity demand but not on the electricity demand profiles. To address this gap, we estimate the impact of energy efficiency measures and policies such as minimum energy performance standards on the peak load by developing a bottom-up model that generates Swiss household hourly electricity demand profiles per appliance based on time use data. The model estimates that evening appliance peak demand can be reduced by 38% when the appliances are replaced by the highest energy efficiency label available on market. We find that changing light bulbs to LED would have the same peak reduction as switching cooking or wet appliances to off-peak periods throughout the year. We also show that the evening appliance peak demand could reduce in 2035 by 24% thanks to the improvement of the energy performance of the stock. Cooking appliances, the least favourable appliances to be involved in demand response, is expected to be the highest contributors to the evening peak in 2035. Our findings show that policy makers should pay due attention to energy efficiency improvement not only for reducing electricity demand but also in order to reduce peak load.

Light-weighted cryptographic algorithms for energy efficient applications

Despite of increasing awareness about information security after the digitization movement and ransomware attack, small business and the general public who perform digital transactions are being attacked. Cryptography has an important place in Security as it works on the data rather than the machine or the network. Data is being transmitted through whichever way, it can be hidden and kept safe by using the right kind of Cryptographic algorithms. But apart from security the pervasive computing and embedded systems create a huge possibility for small and light weighted algorithms, specific applications like WSN need such mechanisms like data aggregation, light-weighted cryptography to enhance the lifetime of the network [1], underwater WSN [2]. In this paper, the need and comparison of light weight cryptographic algorithms is discussed.

Residential energy efficiency in Chile. Policies to reduce firewood dependency

Over 10 million people in Chile are exposed to concentrations of Particulate Matter 2.5 and 10 (PM2.5 – PM10) in excess of the acceptable levels. The main source of emissions in the southern cities is the extensive use of firewood in the residential sector for cooking and heating. Low energy efficiency in buildings and inefficient heating appliances increase firewood combustion intensity and atmospheric pollution. This has led to many cities being declared saturated zones of particulate matter, requiring the implementation of various policies under an Atmospheric Decontamination Plan (ADP). The present research focuses on comparing three housing groups having different implemented strategies and subsidies for improving the energy efficiency of dwellings. A survey was designed to analyze occupants’ fuel consumption patterns and their comfort perception before and after subsidies was applied. Also, it was registered the dwelling intervention to analyze the effectiveness of housing thermal retrofitting. Results showed that thermal retrofitting in housing is random, and does not respond to an accurate study of the interventions’ energy efficiency.