Estimation Of Energy Efficiency Research Articles

Microsecond Discharge Produced in Aqueous Solution for Pollutant Cr(VI) Reduction

This paper presents a detailed analysis of underwater electrical discharge parameters in the treatment of chromium (VI) used as a model pollutant to analyze the reduction process by plasma liquid interaction (PLI). Pin-to-pin microsecond discharges were performed in an aqueous Cr(VI) solution and the processes were characterized using electrical measurements, optical imaging and UV-Vis absorption measurements for [Cr(VI)] estimation. For the first time, the total reduction of Cr(VI) was successfully achieved by PLI process and a maximum energy yield of 4.7 × 10−4 g/kJ was obtained. Parametric studies on electrode geometry, applied voltage, electrodes gap and pulse duration are presented in detail. Finally, an analysis of the process is proposed by comparing our results of the energy yield calculation based on the injected energy with those of the literature and by providing an estimation of the global energy efficiency of the process.

BER Aided Energy and Spectral Efficiency Estimation in a Heterogeneous Network

In this work, we adopt the analysis of a heterogeneous cellular network by means of stochastic geometry, to estimate energy and spectral network efficiency. More specifically, it has been the widely spread experience that practical field assessment of the Signal-to-Noise and Interference Ratio (SINR), being the key physical-layer performance indicator, involves quite sophisticated test instrumentation that is not always available outside the lab environment. So, in this regard, we present here a simpler test model coming out of the much easier-to-measure Bit Error Rate (BER), as the latter can deteriorate due to various impairments regarded here as equivalent with additive white Gaussian noise (AWGN) abstracting (in terms of equal BER degradation) any actual non-AWGN impairment. We validated the derived analytical model for heterogeneous two-tier networks by means of an ns3 simulator, as it provided the test results that fit well to the analytically estimated corresponding ones, both indicating that small cells enable better energy and spectral efficiencies than the larger-cell networks.

LOW CARBON ENERGY 2. Hydrogen energy: problems, achievements, possible risks (review)

Ways to reduce the carbon capacity of Ukraine's economy through the active use of energy efficiency measures in energy, extensive use of renewable energy sources, in particular hydrogen, with possible problems and risks of transition to low-carbon energy. The aim of the work is to assess the contribution of hydrogen use in the perspective of achieving decarbonized energy of Ukraine, taking into account the advantages, available achievements and obstacles to the movement of the economy on this path. To this end, estimates of energy efficiency of primary energy resources according to the EROEI indicator, in particular, renewable energy sources; indicators of environmental friendliness of basic energy resources according to specific (per unit of energy) greenhouse gas emissions are given; IEA data on the volume of global investments in energy efficiency are presented.
 The main scientific and technical results of recent times in the field of research on the processes of production, transportation and end use of hydrogen, obtained by teams from a number of institutes of the National Academy of Sciences of Ukraine. The problems of hydrogen energy are in the focus of close attention of scientists in the country. The use of Ukrainian nuclear power plants for hydrogen production is considered.
 Particular attention is paid to the materials of the draft Hydrogen Strategy of Ukraine until 2050, according to which the volume of hydrogen production in the final period of implementation will be up to 330 billion nm3 annually.
 The risks of formation and development of energy at RES are assessed, the optimal scenarios of the country's economic development are considered.

Estimating energy efficiency using panel stochastic frontier approach: investigating its asymmetric impacts on employment in India

PurposeThis study aims to examine the asymmetric effects of energy efficiency on employment in India. Instead of relying on partial factor energy efficiency measures, this study uses a total factor energy efficiency (TFE) measure to estimate sector-specific energy efficiency for empirical investigation.Design/methodology/approachMulti-sectoral panel data for India from 2000 to 2014 are considered for empirical estimation. The sector-specific energy efficiency estimates (using the TFE measure) are estimated in the initial stage using the stochastic frontier approach (SFA). Then the asymmetric effect of energy efficiency on employment is investigated by using a non-linear panel autoregressive distributed lag model.FindingsThe estimates of energy efficiency display that there is not much significant change in the trend of average energy efficiency over the period. The negative and statistically significant value of the error-correction term confirms the existence of asymmetric cointegrating relationship between energy efficiency and employment in India. Moreover, in the empirical findings, the positive and negative shocks in energy efficiency provide a long-run asymmetric and short-run symmetric effect on employment in India.Originality/valueRather than depending on the absolute measure of energy efficiency (energy to output ratio), this study estimates the sector-specific energy efficiency for India using panel SFA, which provides a relative measure of energy efficiency. Moreover, to the best of the authors’ knowledge, it is the first empirical study investigating the asymmetric impact of energy efficiency on employment at an aggregate level in developing countries like India. By contrast, previous studies have either concentrated on the symmetric effect of energy efficiency on employment or primarily restricted to developed countries.

Efficiency Assessment of the Complex Process of Variable Cutting Parameters

Saving energy and low carbon strategy has becoming the future trend of manufacturing industry. Cutting process in mechanical manufacturing has the characteristics of heavy energy consumption and complex process. The estimation and evaluation of energy consumption and energy efficiency of cutting process are hot topics in research groups and industry. The energy consumption of cutting process is determined by the load, which is related to the cutting parameters under fixed cutting systems, while the cutting parameter might change with the cutting process and material. Based on the relationship between energy consumption and cutting characteristics and the quality requirements, the cutting specific energy u(t) = P(t)/M(t), which is varies with time is proposed to evaluate the energy consumption of various cutting parameters under complex machining processes. The influence of cutting parameters on cutting energy consumption is studied by experiments and a calculation method is proposed to calculate cutting energy consumption. Finally, a case study of complex curve machining in mold manufacturing is illustrated to prove the effectiveness of the proposed evaluation method.

Use of the exergy method to assess the energy efficiency of technical facilities

Improvement of technical objects and systems energy efficiency, the most widespread of which are heat engines, is an urgent task, for the solution of which it is necessary to use various methods. The review of scientific publications allows to single out the exergic analysis based on the exergic balance of power installations of different purpose and design as one of the basic universal methods of energy efficiency estimation. Substantiation of universality of the exergic analysis method on the basis of its theoretical preconditions is given. The basic reserve of increase in power efficiency of thermal engines is the rational use of secondary power resources. With the purpose of an estimation of prospects of use of power resources of heat-carrying agents of cooling systems) the calculation of the heat pump working on a reverse Rankine cycle is executed. On the basis of the executed calculations, the conclusion about prospects of use of the given devices, including for replacement of independent boilers in ship power installations is made. The article contains proposals on use of the exergic method in a complex with traditional methods of estimation of power efficiency of complex technical systems. Advantages of such approach are shown, its possibilities and perspective fields of application are determined. The data obtained as a result of conducted research shows that the use of secondary energy resources of heat engines with the use of recycling turbines and heat pumps of modern designs is promising and allows increasing the fuel utilization factor of reciprocating and gas turbine engines.

Technological progress effects on energy efficiency from the perspective of technological innovation and technology introduction: An empirical study of Guangdong, China

Technological progress plays an important role in energy efficiency improvements. This paper considers two pathways that could accelerate technology development: technology introduction and technological innovation. The technology introduced through foreign direct investment (FDI) may enhance the host country’s independent innovation capability, minimize the risk of independent innovation and lower the cost. To that end, a two-stage analysis was conducted at the industrial level for the period 2000–2018 in Guangdong, China. The first stage included an estimation of total factor energy efficiency (TFEE) scores using the super-efficiency data envelopment analysis (DEA) methodology, while the second one included an exploration of how technological innovation and FDI are affecting energy efficiency by using system GMM regression in the whole sample of the manufacturing sector and sub-sample based on R&D intensity. The results indicate that energy use in most manufacturing industries is efficient and FDI participation induced spillovers from FDI have a significant positive impact on energy efficiency. Moreover, the analysis of the interaction term between FDI and technological innovation show that imitative innovation depends on the transfer technology strategy from foreign-funded enterprises to improve energy efficiency. These results have notable implications for energy use policy and sustainable economic development.

Energetic assessment of a precalcining rotary kiln in a cement plant using process simulator and neural networks

Cement production has been increasing rapidly leading to energy consumption, with serious cost implications and environmental challenges. Energy efficiency is a key component required to maintain the cement company’s environmental strategy. In this study, Aspen Plus process model and neural networks are used to assess the energetic efficiency of a precalcining rotary kiln in a cement production process. Aspen Plus process simulator estimated energy efficiency at 61.30 % using the first law of thermodynamic. Further, for the ANN model, kiln feed, kiln gas, calciner gas, clinker cooling air, and primary air were the operation parameters inputs. ANN model is validated and demonstrated it is capable of predicting cement rotary kiln energy efficiency accurately with a correlation coefficient (R2) of 0.991. In conclusion, the Bootstrap aggregated neural network (BANN) was used to search the optimal operational parameters in achieving the lowest mean square error (MSE) of the energy efficiency. The MSE for training, testing, and validation data sets were 3.64 × 10-5, 3.70 × 10-5, and 5.00 × 10-5 for in the estimation of rotary kiln system energy efficiency. To achieve this optimal condition of 61.5 % energy efficiency, the optimal parameters as determined by ANN (BANN) were kiln feed of 205050 kg/hr, kiln fuel gas of 2821 kg/hr, calciner fuel gas of 5648 kg/hr, clinker cooling air of 247463 kg/hr and primary air of 7309 kg/hr. Consequently, it is recommended that ANN should be combined with Bootstrap aggregated neural network (BANN) for effective prediction and monitoring of energy efficiency for precalcining rotary kiln system.

Estimating energy efficiency increase in national district heating network

A comprehensive methodology has been developed to assess the efficiency potential of national heating networks. Considering the available information on heating networks in Latvia, three different heating system models have been identified depending on the district heating (DH) system scale. To determine the total length of heating networks in populated areas, a regression analysis method is used by analysing the correlation between the inhabitants and the length of heating networks. Authors define different alternatives for heat loss reduction, including the renovation of existing heat pipes and lowering heat carrier temperature. An engineering model is prepared for each alternative based on mathematical calculations to evaluate the economic, environmental, and climate impacts. Estimated costs and savings are used to determine the key economic indicator — net present value (NPV).The results show that the potential reduction in national heat losses from heating network renovation is estimated at 569 GWh. It would reduce the national heat loss rate from around 12% to 6% from the produced heat. Lowering the heating network temperature saves an additional 57 GWh. However, the main benefit of lowering heat carrier temperature is the possibility to use low-cost plastic pipes, which increases the overall economic benefit of the heating network renovation.

Assessment of Short- and Long-Run Energy Efficiency: Evidence from 141 Countries

Several studies have estimated the energy efficiency performance of firms, countries and regions. Recently, the efficiency literature highlighted two types of efficiencies- persistent and transient efficiency. However, several studies have failed to distinguish between these two types of efficiencies. In the light that there are no studies addressing this issue from a global perspective, this paper adopts the stochastic frontier approach and the Kumbhakar, Lien and Hardaker (KLH) model in the estimation of persistent, transient and total energy efficiency of 141 countries during the period 1980-2016. Our findings show that global energy efficiency issue is structural in nature. Increasing both transient and persistent energy efficiency will save 13% and 31% of total energy consumed, respectively. Therefore, environmental and energy security issues will profit significantly from long-term policies rather than the short-term policies. Thus, countries should focus on addressing environmental and energy issues using long-term policies.

Dynamic Energy Efficiency, Energy Decoupling Rate, and Decarbonization: Evidence from ASEAN+6

Improving energy efficiency is widely identified as shifting energy usage to an optimal status in order to ultimately strengthen a country’s competitiveness and development, and indeed this is of particular relevance to the Association of Southeast Asian Nations plus Six’ (ASEAN+6). The traditional data envelopment analysis (DEA) approach has extensively been employed for estimating energy efficiency, but it does not properly utilize the weight in the DEA model to probe the behavior change of a decision making unit (DMU). This research therefore applies a progressive time-weighted dynamic efficiency model (PTDEM) to estimate the energy efficiency of ASEAN+6 and discusses the issues concerning their energy decoupling rates and decarbonization. The proposed model herein fully considers a DMU’s behavior change by estimating its energy efficiency. Empirical results reveal that: (i) improvements in energy efficiency within ASEAN are greater than in the other six countries; (ii) members of ASEAN still have more room for improvement than the other six countries with regard to achieving the standard ratio of the energy decoupling rate; and (iii) there is no evidence of convergence to decarbonization within ASEAN+6.

An Energy Efficiency Estimation Procedure for Small Wind Turbines at Chosen Locations in Poland

Contrary to the extensive amount of research on large wind turbines, substantial analyses of small wind turbines are still rare. In the present study, the wind energy potential of three locations in Poland is analyzed using real wind data from a five-year period and the parameters of the selected turbine model. Appropriate simulations are performed to assess the energy efficiency of the analyzed investments at a coastal, foothill, or lowland site. According to the results, the most favorable location for a small wind turbine is the coastal site (wind zone I). The payback time at this location is approximately 13 years, whereas the payback times at the other two analyzed are more than 3 times longer. The payback periods for the latter locations significantly exceed the estimated lifetime of the wind turbine, ruling out their economic viability. The cost of electricity generation varies greatly, from 0.16 EUR/kWh at the coastal location to 0.71 EUR/kWh at the lowland location. These results provide a reference for developing more efficient solutions, such as the use of a turbine with a shielded rotor, which can increase the power of the turbine by approximately 2.5 times.

THE INFLUENCE OF THE CHANGES IN WIND VELOCITY ON THE OUTER HEAT EXCHANGE OF THE BUILDINGS

When choosing architectural and planning solutions, such climatic factors as air temperature and humidity, having scalar quantities, as well as solar radiation, wind and precipitation having vector characteristics, must be taken into account. The calculated climatic parameters for the design of building enclosing structures, heat loss calculations and heat supply regulation are provided in the current documentation on norms and standards. The practical exploitation of various buildings demonstrates that in terms of initial climatic data, the choice of design parameters is not always efficiently justified; hence, the influence of the environment on the heating regime of the structures is insufficient in the estimations and sometimes erroneous. The wind is one of such climatic parameters. Its velocity and repeatability impact the heat exchange of the building structure with the environment as well as the alteration in temperature regime. The wind current towards the building creates additional pressure on the facade of the construction from the wind side direction. This leads, firstly, to air infiltration via the enclosing structures, and secondly, to the rise of heat exchange from the outer surface of the wall on the windward side. Based on estimated and analytical research, the values of the change in wind velocity depending on the altitude were analyzed, and its influence on the heat loss during heating of multi-storey buildings was assessed. The alterations in the wind velocity depending on the altitude were analyzed in the conditions of dense (urban) and broad construction. Besides, the authors presented the dependence of the convective component of the heat transfer coefficient of the outer surface of the structure on the values of the wind velocity. Based on the performed and presented calculations, it can be noticed that the heat transfer of the external structure will be much higher for multi-storey buildings than for mid-rise constructions. Thus, the convective component of the heat transfer coefficient of the outer surface rises by 36 % when the wind velocity increases from 5 m/s to 7 m/s. If not taking into consideration this dependence in the design, it can significantly influence the estimation of heat loss and energy efficiency of buildings, especially when it is about the increased percentage of facades glazing. The authors of the article assessed the heat loss for heating the windward and leeward facades at average values of the outside air temperature during the heating season in Ukraine. Hence, for constructions higher than 70 m with a calculated wind velocity of 5 m/s, heat losses increase from 10 % to 19 %. Such great difference in heat loss between the windward and leeward walls of the building requires increased thermal protection from the prevailing winter winds. Therefore, when designing multi-storey buildings, it is necessary to take into account changes in wind velocity according to the altitude. The obtained results can be useful both for choosing architectural and planning solutions, like the materials for external enclosing structures and for the objective assessment of the wind protection degree of individual buildings and territories.

Estimation of energy efficiency of non-tractive rolling stock

Purpose. One of the priority areas for improving the transportation process by railway transport is to increase its energy efficiency. Preliminary quantitative assessment of the resistance of the creep forces wagon, determination of the influence of damping on the amount of power resistance force at the resonance modes. Methododology. The study was conducted using mathematical modeling software system MEDYNA and an analytical method. Findings Energy consumption for overcoming resistance from forces creeps up a significant portion of total energy consumption to overcome the resistance movement, the resonance modes is a sharp increase in power consumption; its value significantly affects the value of damping. Originality. It is found that energy consumption in order to overcome the resistance of the power creeps up is a significant portion of total energy consumption to overcome the resistance movement, especially in the resonant modes. Practical value. The results can also be applied for development of a mathematical model of the car and the methodology for assessment of the resistance to motion that taking into account the resistance of the creep forces and the dissipation of energy in the environment as a hanging.

The underlying drivers of economy-wide energy efficiency and asymmetric energy price responses

A good understanding of energy efficiency trend and its potential underlying drivers is required when considering policies for energy conservation and environmental sustainability. In light of this, we estimate energy efficiency trends using index decomposition analysis, data envelopment analysis and stochastic frontier analysis as robust methods. The driving factors (including asymmetric price responses) are examined using a dynamic panel model estimated by Arellano and Bond (1991) GMM estimator. The application for 32 OECD countries found that none of the three methods leads to a consistent ranking between energy efficiency estimates and energy intensity – corroborating the criticism that energy intensity is not a good proxy for energy efficiency. The panel-data regressions using the energy efficiency estimates from the three methods show similarities in the impacts of the drivers (including energy price, foreign direct inflows, trade openness, population growth, temperature etc.) on energy efficiency. Although the results of asymmetric price responses of energy efficiency estimates vary slightly, we found insignificant evidence of asymmetric effects of total energy price but there are asymmetric responses with energy-specific prices. Thus, using energy-specific prices as well as allowing for asymmetric price effects in analysing drivers of energy efficiency is apt and informative in formulating energy policies.

Institutional quality and its spatial spillover effects on energy efficiency

Several studies have studied the determinants of energy efficiency. However, the influence of government institutions was mostly ignored as only few studies have provided evidence on the role of institutions in enhancing domestic energy efficiency. In this paper, we extend the previous literature by asking whether neighboring country's institutions could also have an impact on domestic energy efficiency. Thus, with the stochastic frontier approach and spatial econometric model, we investigate the spatial effect of institutional quality on energy efficiency in a panel of 99 countries (economies) for the period 1995–2016. Our results, first confirm the presence of spatial correlations in energy efficiency across countries. Secondly, we discover that the direct positive effect of institutional quality on energy efficiency is such that it overcomes the insignificant indirect negative effect, which suggests a total positive and significant effect. Our results, therefore, indicate that institutional quality matters in energy efficiency improvement and being close to countries with good institutional framework has a positive effect on domestic energy efficiency. Finally, the energy efficiency estimates demonstrate that global energy issue can only be addressed with long-term policies that increases technological progress.

Does innovative capability enhance the energy efficiency of Indian Iron and Steel firms? A Bayesian stochastic frontier analysis

Abstract This paper aims to estimate energy efficiency and quantify the energy-saving potential of Indian iron and steel firms. Further, we explore the influence of different innovative capability channels that can enhance energy efficiency. Firm-level data of 82 Indian iron and steel firms over the period of 2003–2017 has been taken to investigate the issues. Bayesian stochastic frontier analysis (SFA) has been adopted to measure underlying energy efficiency. The results show that most of the firms can reduce half of their energy consumption, while substantial heterogeneity exists in terms of energy efficiency. The Bayesian SFA outperforms classical SFA and documents slightly declining evidence of energy efficiency over time. The analysis also depicts that investing in R&D expenditure, patenting activity, and disembodied technology flow enables firms to achieve higher stage energy efficiency. ISO 14001 certified firms do not perform better than non-certified firms, and there is no significant effect of embodied technology on the firms' energy efficiency.

Potato thin layer convective dehydration model and energy efficiency estimation

The dehydration parameters (temperature, thickness, and mass load) statistically significantly (p<0.05) affect the thin-layer convective dehydration of potato slices. The slices with thicknesses of 3, 5, and 8 mm were dehydrated as monolayers at different temperatures (30, 50, and 70 °C) and mass load (1.00, 0.63, and 0.38 kg m-2). The results showed that the shortest dehydration time (183 minutes), the smallest energy consumption (0.176 kWh), and the smallest emission of carbon dioxide (0.17 kg) had the dehydration model of potato slices with a 3 mm thickness, 0.38 kg m-2 mass load, dehydrated on the temperature of 70 °C. Dehydration of potato slices of 8 mm slice thickness dehydrated at 70 °C, with 0.38 kg m-2 mass load, showed the highest resistance to mass transfer (the maximum effective moisture diffusivity 2.3761 × 10-7 ± 4.45646 × 10-9 m2 s−1) and the minimum activation energy (27.02 kJ mol-1). Data obtained from these mathematical models could predict and optimize the thin layer dehydration of potato slices, with a dominant influence of temperature and potato slice thickness parameters as variables.

Методика оптимизации энергомассовых характеристик системы электропитания геостационарного космического аппарата

This article determines a methodology to maximize a specific power of the electrical power system of a geostationary spacecraft, using the EPS simulation model. A typical (for GEO spacecraft) fully-regulated EPS structure is considered. The advantages of using the full bridge quasi-resonant converters with galvanic isolation are considered. The results of the energy efficiency estimation of power converters at various ranges of input voltages, as well as the criteria and conditions for calculating the positive energy budget of a GEO spacecraft are presented. The application of the EPS simulation model is shown and the results of optimization of the proposed EPS energy and mass characteristics for 6 and 13 kW payloads are described

GHG Emissions and Efficiency of Energy Generation through Anaerobic Fermentation of Wetland Biomass

We conducted the Life Cycle Analysis (LCA) of energy production from biogas for maize and three types of wetland biomass: reed Phragmites australis, sedges Carex elata, and Carex gracilis, and “grassy vegetation” of wet meadows (WM). Biogas energy produced from maize reached over 90 GJ ha−1, which was more than four times higher than that gained from wetland biomass. However, an estimation of energy efficiency (EE) calculated as a ratio of energy input to the energy produced in a biogas plant showed that the wet fermentation (WF) of maize was similar to the values obtained for dry fermentation (DF) of sedge biomass (~0.30 GJ GJ−1). The greenhouse gases (GHG) emissions released during preparation of the feedstock and operation of the biogas plant were 150 g CO2 eq. kWhel.−1 for DF of sedges and 262 g CO2 eq. kWhel.−1 for WF of Phragmites. Compared to the prevailing coal-based power generation in Central Europe, anaerobic digestion (AD) of wetland biomass could contribute to a reduction in GHG emissions by 74% to 85%. However, calculations covering the GHG emissions during the entire process “from field to field” seem to disqualify AD of conservation biomass as valid low-GHG energy supply technology. Estimated emissions ranged between 795 g CO2 eq. kWhel.−1 for DF of Phragmites and 2738 g CO2 eq. kWhel.−1 for the WM and, in most cases, exceeded those related to fossil fuel technologies.