The Effectiveness of Extended Schedules of Heating Regulation at CHP Plants with Decreasing Normative Design Temperature of the Supply Water

The aim of the work is a computational study of the effectiveness of the extended schedules of heating regulation at steam turbine CHPPs with a decrease in the normative design temperature of the supply water. The study was carried out on adequate mathematical models of CHP tur-bines and heat supply systems, considering heat pipelines' actual diameters and lengths. The main energy efficiency indicator is the specific reference fuel consumption for electricity sup-ply, calculated under comparable conditions for the operating modes of turbine plants and the load of the heat supply system. The study took into account the electricity consumption for the drive of network pumps, standard heat losses in heating networks and the electricity generation for the heat consumption of CHPPs. The study results allowed for the first time to determine the integral indicators of the energy efficiency of work during the transition of CHPPs from the normative design ones to the temperature schedules reduced by the temperature of the supply water. At the same time, the calculations revealed the limitations on the parameters of the extended schedules of regulation when transitioning to reduced temperature schedules. The most important results of the work should also be attributed to the determination of the optimal schedules of the temperature of the supply water for different values of the district heating coef-ficient of the CHPP. The results obtained are essential for assessing the efficiency of the transi-tion of heat supply systems to reduced supply water's design temperatures when using modern heating regulation schedules.

Energy-efficient variable frequency asynchronous electric drive

Currently, there are quite a large number of various scientific papers on the creation of a controlled asynchronous engine and the optimization of its modes, and the availability of acceptable results for practical implementation, but there is still no single generally accepted approach to solving the problem. In this regard, the issue of synthesis of scalar control systems that provide the minimum value of one or another criterion of energy efficiency is relevant. In this paper, we consider the obtained mathematical model of an asynchronous engine (AE), which differs from the known ones in that the parameters of the substitution scheme are expressed in terms of the stator and rotor conductivities. The energy characteristics of the AE in the sliding function are obtained, which make it possible to determine the dependences of the active and reactive components of the AE current and the possibility of their redistribution within the nominal value of the AE phase current. The principle of optimal frequency-current control of AE is formulated, which differs from the known ones in that, as an energy efficiency indicator, the value of the maximum energy efficiency of AE is used, expressed as the ratio of the active resistance of the rotor circuit to the total conductivity of the AE phase.

Energy efficiency financing and the role of green bond: policies for post-Covid period

PurposeOne of the major negative effects of the Coronavirus outbreak worldwide has been reduced investment in green energy projects and energy efficiency. The main purpose of this paper is to study the role of green bond proposed by the World Bank in 2008, as a reliable instrument to enhance the capital flow in energy efficiency financing and to develop green energy resources during and post the current challenging global time.Design/methodology/approachWe model energy efficiency for 37 members of OECD through a panel data framework and quarterly data over 2007Q1–2020Q4.FindingsThe major results reveal the positive impacts of issued green bonds and regulatory quality index on energy efficiency, while any increase in inflation rate and urbanization decelerates the progress of raising energy efficiency.Practical implicationsAs highlighted concluding remarks and policy implications, it can be expressed that the tool of green bond is a potential policy to drive-up energy efficiency financing and enhancing environmental quality during and post-COVID period. It is recommended to follow green bond policy with an efficient regulation framework and urbanization saving energy planning.Originality/valueTo the best of the authors' knowledge, although a few scholars have investigated the impacts of COVID-19 on green financing or examined the energy efficiency financing, the matter of modeling energy efficiency–green bond relationship has not been addressed by any academic study. The contributions of this paper to the existing literature are: (1) it is the first academic study to discover the relationship between energy efficiency and green bond in OECD countries, (2) since our empirical part provides estimation results based on quarterly data covering the year of 2019 and 2020, it may offer some new policy implications to enhance energy efficiency financing in and post-COVID period, (3) furthermore, we consider energy efficiency indicator (mix of industrial, residential, services and transport energy efficiency) as the dependent variable instead of using the simple energy intensity variable as a proxy for energy efficiency.

Investigation of an asynchronous electric drive with frequency control

Currently, there are quite a large number of various scientific papers on the creation of a controlled asynchronous motor and optimization of its modes, and the availability of acceptable results for practical implementation, but there is still no single generally accepted approach to solving the problem. In this regard, the issue of synthesis of scalar control systems that provide the minimum value of a particular energy efficiency criterion is relevant. In this paper, we consider the obtained mathematical model of an asynchronous motor (AD), which differs from the known ones in that the parameters of the substitution circuit are expressed in terms of the stator and rotor conductivities. The energy characteristics of the AD in the sliding function are obtained, which make it possible to determine the dependences of the active and reactive components of the AD current and the possibility of their redistribution within the nominal value of the AD phase current. The principle of optimal frequency-current control of AD is formulated, which differs from the known ones in that, as an energy efficiency indicator, the value of the maximum energy efficiency of AD is used, expressed as the ratio of the active resistance of the rotor circuit to the total conductivity of the AD phase. Keywords: ASYNCHRONOUS MOTOR, ASYNCHRONOUS ELECTRIC DRIVE, EFFICIENCY, POWER FACTOR, ENERGY EFFICIENCY, CIRCUIT CONDUCTIVITY, REPLACEMENT CIRCUIT, SLIP

Improving the energy efficiency of the pipeline system by ensuring its linear flow characteristic

Recently, SMART positioners have been widely used to control the on-off and control valves. These devices allow you to set an arbitrary user dependence of the valve travel on the control signal. This makes it possible to provide a linear throughput for the entire piping system. This allows the use of smaller type control valves while maintaining the control range. Accordingly, the energy consumption for controlling the shutoff element is reduced; the value of the reinforcement energy efficiency indicator is improved. In that work analytically calculates a user dependency that takes into account the value of pipeline throughput and allows to obtain a linear throughput of the pipeline system in the entire range of control signal change.

Sustainable Development and Competition: new evidence from EU countries

In this paper we present energy efficiency targets indicators of sustainable development and we discuss the role of competition, on promoting and enhancing sustainability and pricing issues. For this purpose, we present statistical evidence of energy efficiency targets indicators, we highlight the degree of competition of electrical markets in various member states and we present the effect of the degree of competition on electrical prices and energy efficiency targets. The empirical results indicate that the higher the degree of competition in electrical markets, the lower the electrical prices. Furthermore, less concentrated electrical markets exhibit higher rates of greenhouse gas emissions and share of renewable energy in total energy consumption than in the less competitive markets. Even though the empirical results do not reveal a clear-cut picture in regard with the effect of competition on energy efficiency indicator, EU28 countries have a primary energy consumption of almost 1.526 Mtoe in 2019 and they are quite close to achieve the energy efficiency target of Europe 2020 strategy implemented by Directive 2012/27/EU on energy efficiency.

Energy Efficiency: Indicator, Estimation, and a New Idea

Energy efficiency has long been an important issue to the global economic and political theaters; however, searching for an effective and concise measure for efficiency remains a contentious and intriguing topic. There are two obvious flaws with the commonly used metrics in existing literature. First, there is a sense of confusion and misunderstanding between the definitions of energy efficiency and efficacy. As a result, the formulae and methods for measuring efficiency are often the subject of criticism. Second, even if the definition of efficiency is clear, the method of estimation can be quite cumbersome, making it difficult to comprehend or implement. This study attempts to address these two issues. With an OECD comparative dataset, it first presents the contradiction between efficiency and efficacy, explains the loss of effectiveness with the existing measurements, and then proposes a new and easy-to-use method for gauging energy efficiency, so that the succinctness and robustness of the measurement can be re-established. The paper serves as a guide to those who are interested in the controversial issues related to measuring energy efficiency. Both practitioners and policy makers will find an easy and reliable tool from this paper for measuring energy efficiency.

Assessment of methane emission traits in ewes using a laser methane detector: genetic parameters and impact on lamb weaning performance

The aim of the present study was to derive individual methane (CH4) emissions in ewes separated in CH4 respiration and eructation traits. The generated longitudinal CH4 data structure was used to estimate phenotypic and genetic relationships between ewe CH4 records and energy efficiency indicator traits from same ewes as well as from their lambs (intergenerational perspective). In this regard, we recorded CH4 emissions via mobile laser methane detector (LMD) technique, body weight (EBW), backfat thickness (BFT) and body condition score (BCS) from 330 ewes (253 Merinoland (ML), 77 Rhön sheep (RH)) and their 629 lambs (478 ML, 151 RH). The interval between repeated measurements (for ewe traits and lamb body weight (LBW)) was 3 weeks during lactation. For methane concentration (µL L−1) determinations in the exhaled air, we considered short time measurements (3 min). Afterwards, CH4 emissions were portioned into a respiration and eructation fraction, based on a double normal distribution. Data preparation enabled the following CH4 trait definitions: mean CH4 concentration during respiration and eructation (CH4r+e), mean CH4 concentration during respiration (CH4r), mean CH4 concentration during eructation (CH4e), sum of CH4 concentrations per minute during respiration (CH4rsum), sum of CH4 concentrations per minute during eructation (CH4esum), maximal CH4 concentration during respiration (CH4rmax), maximal CH4 concentration during eructation (CH4emax), and eructation events per minute (CH4event). Large levels of ewe CH4 emissions representing energy losses were significantly associated with lower LBW (P<0.05), lower EBW (P<0.01) and lower BFT (P<0.05). For genetic parameter estimations, we applied single- and multiple-trait animal models. Heritabilities and additive genetic variances for CH4 traits were small, i.e., heritabilities in the range from <0.01 (CH4r+e, CH4r, CH4rmax, CH4esum) to 0.03 (CH4rsum). We estimated negative genetic correlations between CH4 traits and EBW in the range from −0.44 (CH4r+e) to −0.05 (CH4rsum). Most of the CH4 traits were genetically negatively correlated with BCS (−0.81 for CH4esum) and with BFT (−0.72 for CH4emax), indicating same genetic mechanisms for CH4 output and energy efficiency indicators. Addressing the intergenerational aspect, genetic correlations between CH4 emissions from ewes and LBW ranged between −0.35 (CH4r+e) and 0.01 (CH4rsum, CH4rmax), indicating that breeding on reduced CH4 emissions (especially eructation traits) contribute to genetic improvements in lamb weaning performance.

Energy Efficiency Of National Economy: Social, Economic And Ecological Indicators

The paper aimed to formalise the relationship between the level of Ukrainian energy efficiency from 30 indicators of social, ecological and economic development of the country. The main purpose of the study is to identify the impact and dependence of socio-ecological and economic indicators on the level of energy efficiency using multiple correlation-regression analysis. The systematisation of the analysed results allowed identifying the core directions to overcome the issues of the slow pace of energy efficiency improvement and the development of carbon neutrality of the country. The relevance of this scientific solution to the problem is that the level of energy efficiency is influenced by a large number of socio-ecological and economic factors sometimes independent of each other. The authors analysed the relationship between the level of energy efficiency and socio-ecological and economic indicators of country development. The investigation consisted from the following stages: conducting polynomial-regression analysis of energy efficiency development in Ukraine; development of correlation-regression multiple models of relationships between energy efficiency indicator and socio-ecological-economic indicators; explaining the conclusions and providing recommendations considering the findings. The object of the study was the processes of energy efficiency relationships with 30 indicators of socio-ecological and economic development, namely how much they affect the energy development of the country. The conclusions were theoretical and practical in terms of the impact on the level of energy efficiency of interdisciplinary indicators. The conclusions which proved by the empirical findings allowed identifying weaknesses in the development of the national economy, as well as to improve and increase the energy potential of the country through energy efficiency development strategies due to the studied determinants that have a strong impact on the level of energy efficiency. Keywords: energy efficiency, carbon-free economy, sustainable development, energy sector, green energy, energy security.