Modeling of Magnetic Refrigeration Device by Using Artificial Neural Networks Approach

The aim of this work is to use multi-layered perceptron artificial neural networks and multiple linear regressions models to predict the efficiency of the magnetic refrigeration cycle device operating near room temperature. For this purpose, the experimental data collection was used in order to predict coefficient of performance and temperature span for active magnetic refrigeration device. In addition, the operating parameters of active magnetic refrigerator cycle are used for solid magnetocaloric material under application 1.5 T magnetic fields. The obtained results including temperature span and coefficient of performance are presented and discussed.

Research of Solar Energy Potential of Photovoltaic Installations on Enclosing Structures of Buildings

Under conditions of limited space for the placement of photovoltaic modules, exploitation of rooftop and facade photovoltaic power plants are highly relevant. One of their main advantages is the possibility to integrate them into both existing and new consumer infrastructures, regardless of their configuration, using the building envelope. On the example of the specific tilt angles relative to the horizon of the receiving surfaces of the modules when they are placed on the enclosing structures of the building for southern spatial orientation, analysis of the utilization level of solar energy potential of the region is carried out. The inclination angles of the enclosing structures, which are characterized by the closest electric energy generation to the generation by modules of optimal spatial orientation, are revealed. There were also determined spatial orientations of the enclosing structures, for which the installation of modules of photovoltaic power plants is not recommended.

Place Selection of Sectionalizing Units in 0.38 kV Power Networks

In the paper there is the developed methodology for selecting the installation places and number of sectionalizing units which allows solving the problem according to the criterion of providing the necessary sensitivity of the protective devices installed on the line input. The obtained expression allows calculating the maximum distance to the installation place of a sectionalizing unit. It also allows determining the need to install a sectionalizing unit in a power line. If a sectionalizing unit is installed to protect an outgoing line, the technique can also be used taking into account the adjustment of the original calculated data. The developed methodology for determining the installation place of a sectionalizing unit can be used for other purposes. For example, it allows selecting the cross section of power lines in terms of the protection sensitivity when designing power lines or when reconstructing them.

Modeling the Levelized Cost of Energy for Concentrating Solar Thermal Power Systems Based on a Nonlinear AutoRegressive Neural Network With Exogenous Inputs

This article presents the results of the development of a mathematical model for predicting the levelized cost of energy (LCOE) for solar concentrating thermal power systems (CSP systems) based on a nonlinear autoregressive neural network with exogenous inputs (NARX). A two-layer NARX network with sigmoid hidden neurons and linear output neurons has been developed. The input layer is made up of the following variables: the volume of input power of CSP systems in the world, the total world energy consumption, domestic energy consumption, domestic gas consumption, domestic consumption of coal and lignite, domestic energy consumption, the share of renewable energy in electricity generation, the share of wind and solar energy in the production of electricity, carbon dioxide emissions from fuel combustion, the price of Brent oil against the US dollar, and the average price for natural gas auctions. The output layer specifies LCOE values for CSP systems.

Technical Analysis of a Novel Wind-Powered Hydrogen System for Sustainable Development

In the current analysis, a novel hybrid energy system operating on the basis of wind and hydrogen energy is designed. The simulation-based optimization has indicated the stochastic nature of wind power technology in comparison with hydrogen power specially when being integrated with the transportation network. The multi-criteria decision-making approach in the current analysis has also suggested that, among the examined cases, the most appropriate configuration of the hybrid energy system is leading to optimum levels of wind energy production, fuel flow rate, oxygen, hydrogen utilization, and stack consumption (including air and fuel) with the equivalents of 1,700 kW, 84 lpm, 75%, 717.37 kg/m3, 140 lpm, and 48 lpm, respectively. The maximum net revenues of the entire hybrid system are estimated to be €4,470 per month. It has been concluded that a transportation network fueled by wind and hydrogen systems can lead to a reduced level of environmental footprints.

The Politics of Climate Change and the Rising Demand for Global Energy in the 21st Century

Established that most governments prefer to boost global energy supply because it improves economies and translates to gainful employment for citizens, the rising global demand for energy from various sectors continues to trigger unprecedented consequences on the environment, resulting in hazardous implications. Hence, scientists argue that the rising demand for global energy by industrialized nations increases the vulnerability of persons and polities where these energy and mineral resources abound. Consequently, governments, multinationals, etc. are at a crossroads regarding how best to address this dilemma. Creswell's mix-method research deign and Merlyn's ex-post facto research methods for analyzing qualitative and quantitative data previously obtained from similar studies were used for attaining the objectives of the research. The study identified troubling and high-level politicking at play in most affected countries. Recommendations geared towards addressing the dilemmas emanating from the rising global demand for energy by governments and scholars were proffered.

Optimizing Layout of Distributed Generation Sources of Power Supply System of Agricultural Object

The increasing penetration of photovoltaic technology calls for the development of an effective method for optimization of grid-connected photovoltaic power plants. Although extensive studies on the definition, implementation, and optimization of these systems have been conducted, the design and management of a smart energy system remains a critical challenge. The purpose of the work is to increase efficiency of power supply system of agricultural facility by optimizing the placement and selection of parameters of photovoltaic sources of distributed generation. Application of photovoltaic sources of distributed generation as part of power supply system of agricultural enterprise allows to reduce the total consumption from the network in average basing on solar intensity data for 22 years by 40-53% from April to October, which is most expedient in view of the fact that this is a period of intensive work of the enterprise and the greatest load on its consumers; by 24-30% in February, March, and October; and by 14-17% the rest of the time.

Global Pandemics on European Electrical Energy Markets

Global pandemics cause crises influencing all branches of economies. Basing on the currently striking COVID-19 pandemic, the authors analyze in this paper to what extent they may impact selected European electrical energy markets. For this, this research performs an empirical survey of the evolution of three market condition indicators: power demand, day-ahead energy prices, and prices of shares of power companies active in the generation sector. These are analyzed on examples of four European countries that all reacted differently to the spreading epidemic at governmental level: Italy, the United Kingdom, Poland, and Sweden. The evolution of indicators is analyzed for the period of COVID-19 outbreak in Europe, from January 27th 2020 until May 27th 2020 and checked with their behaviors in previous periods of time statistically. The study showed that global pandemics may have high impact on power demand and on share prices of power companies. Yet, the impact on day ahead energy prices is less evident and seems not present.

Techno-Economic Evaluation of Hydrogen Fuel Cell Electricity Generation Based on Anloga (Ghana) Wind Regime

This paper assesses the performance of electricity generation using wind/hydrogen/fuel-cell technology. The intermittency of renewables, especially wind, and the need for storage of excess energy make them unattractive for continuous generation of electricity. This paper focuses on the wind resource of Anloga (Ghana) and the potential of hydrogen production from water electrolysis. The assessment of this system covers three main areas including the potential energy generation, environmental impacts, and economic impacts. The paper adopted analytical models of energy generation of fuel cell and hydrogen technologies and further performs their assessment using HOMER software. It was revealed that the annual electricity production from the hydrogen fuel cell is 25,999kW/yr, with an annual capacity shortage of 392kW/yr representing a 10% capacity shortage. The levelized cost of electricity was 0.602$/kWh and the emissions have been completely minimized as compared to diesel generation plants.

Research of Heat Losses of Solar Collectors and Heat Accumulators

The article discusses the features of heat losses by convection and radiation of flat solar collectors on the basis of a non-stationary thermal model and program. The connection of heat losses with the generalized heat loss coefficient of solar collectors is shown. The article also deals with the problem of determining the distribution of temperatures and heat losses by convection and radiation of a thermal insulation system – accumulating body (water) for a spherical heat accumulator under symmetric boundary conditions. The problem is solved numerically according to the program developed on the basis of the proposed “gap method.” The method and program for the numerical calculation of heat losses and temperatures in time in a spherical two-layer heat accumulator with symmetric boundary conditions, taking into account both incident and intrinsic radiation, have been developed. The program has been developed for a “long” two-layer cylindrical heat accumulator of solar collectors.