Energy production from biogas can play a pivotal role in many European countries, and specifically in Italy, for three main reasons: (i) fossil fuels are scarce, (ii) imports cover large shares of internal demand, and (iii) electricity and heat production from biogas is already a consolidated business. Nonetheless, in Italy, current legislation and incentive policies on electricity generation from biogas are causing a stagnation of the entire sector, which may lead to the shutting down of many in-operation plants in the years 2027−2028 and the consequent loss of 573 MWel over a total of 1400 MWel. This work aims to investigate the potential of revamping biogas power plants in prolonging operation until the end of the plants’ useful life, regardless of the implementation of a new government’s incentive schemes. Based on the time-series analysis of electricity prices in Italy and a case study representative of the vast set of in-operation power plants, our findings show that 700 plants w... [more]

In this paper, a bidirectional converter with multi-mode control strategies is proposed for a battery energy storage system (BESS). This proposed converter, which is composed of a half-bridge-type dual-active-bridge (HBDAB) converter and an H-bridge inverter, is able to operate the BESS with different power conditions and achieve the DC−AC function for lower input DC voltage applications. For the HBDAB converter, the variable-frequency control (VFC) and phase-shift control (PSC) are both adopted to achieve zero-voltage switching over a wider power range and the battery module balance control capability for BESS, respectively. In addition, the interleaved configuration is used to reduce the current ripple and increase the overall current rating. For the H-bridge inverter, the unipolar control mode (UCM) and totem-pole control mode (TPCM) are adopted to manage the real and reactive current control under different AC grid conditions. The UCM offers a reduction in current ripple for real a... [more]

During a turbine’s lifetime, minimizing the cost of power production should be the primary aim in addition to attaining high technical efficiency. Thus, this paper was aimed at enhancing the aerodynamic efficiency of a site-specific small wind turbine considering the cost of energy as one of the design parameters. The wind distribution of a specific site was employed to characterize the wind using the Weibull distribution method. The aerodynamics of a typical 5 kW wind turbine blade were investigated by implementing a blade element method (BEM) using a MATLAB code that applied the advancements and improvements with different modifications and which was validated by engaging computational fluid dynamics (Ansys-Fluent). The optimal pitch angle was then employed to further promote the performance characteristics of the blade. The cost of energy was reformulated in terms of rated power considering a cost variation of the main components that deviates with the rated power. Accordingly, the... [more]

The traditional Fixed Band Hysteresis Current Control (FB-HCC) though being widely used for the current control of grid integrated voltage source inverter (GI-VSI), has the drawback of variable switching frequency. To overcome this drawback, Complex Programmable Logic Device (CPLD) based switching scheme is proposed in this paper. The proposed method calls for a single reference wave and the control concept is to terminate the rising and falling inductor current (iL) either by the comparator or by the CPLD, based on the nature of its slope. Termination of the iL with steeper slope by the comparator ensures lower current ripple, whereas the CPLD ensures constant switching frequency (fsw). However, the iL obtained with the proposed logic has a DC offset, which is corrected by modifying the reference. The basic concept, switching logic, and reference correction are thoroughly detailed. MATLAB/Simulink results are included to verify the proposed concept. The constant frequency operation of... [more]

Low-grade faults play an important role in controlling oil and gas accumulations, but their fault throw is small and difficult to identify. Traditional low-grade fault recognition methods are time-consuming and inaccurate. Therefore, this study proposes a combination of a simulated low-grade fault sample set and a self-constructed convolutional neural network to recognize low-grade faults. We used Wu’s method to generate 500 pairs of low-grade fault samples to provide the data for deep learning. By combining the attention mechanism with UNet, an SE-UNet with efficient allocation of limited attention resources was constructed, which can select the features that are more critical to the current task objective from ample feature information, thus improving the expression ability of the network. The network model is applied to real data, and the results show that the SE-UNet model has better generalization ability and can better recognize low-grade and more continuous faults. Compared with... [more]

In this study, a newly developed zero-dimensional electrochemical model was used for modeling and controlling proton-exchange membrane fuel cell (PEMFC) performance. Calibration of the model was performed with measurements from the fuel cell stack. Subsequently, a compressor and a humidifier on the cathode side were sized and added to the existing model. The aim of this work was to model the PEMFC stack and balance of plant (BoP) components in detail to show the influence of operating parameters such as cathode pressure, stack temperature and cathode stoichiometric ratio on the performance and efficiency of the overall system compared to the original model using a newly developed real-time model. The model managed to predict the profile of essential parameters, such as temperature, pressure, power, voltage, etc. The most important conclusions from this particular case are: the cell power output is only slightly changed with the variations in stoichiometric ratio of the cathode side and... [more]

With large penetration of wind power into power grids, the accurate prediction of wind power generation is becoming extremely important. Planning, scheduling, maintenance, trading and smooth operations all depend on the accuracy of the prediction. However due to the highly non-stationary and chaotic behaviour of wind, accurate forecasting of wind power for different intervals of time becomes more challenging. Forecasting of wind power generation over different time spans is essential for different applications of wind energy. Recent development in this research field displays a wide spectrum of wind power prediction methods covering different prediction horizons. A detailed review of recent research achievements, performance, and information about possible future scope is presented in this article. This paper systematically reviews long term, short term and ultra short term wind power prediction methods. Each category of forecasting methods is further classified into four subclasses an... [more]

Spatially separated locations may differ greatly with respect to their electricity demand, available space, and local weather conditions. Thus, the regions that are best suited to operating wind turbines are often not those where electricity is demanded the most. Optimally, renewable generation facilities are constructed where the maximum generation can be expected. With transmission lines limited in capacity though, it might be economically rational to install renewable power sources in geographically less favourable locations. In this paper, a stochastic bilevel optimisation is developed as a mixed-integer linear programme to find the socially optimal investment decisions for generation expansion in a multi-node system with transmission constraints under an emissions reduction policy. The geographic heterogeneity is captured by using differently skewed distributions as a basis for scenario generation for wind speeds as well as different opportunities to install generation facilities... [more]

Photovoltaic installations (PVs) are currently one of the fastest-growing sources of renewable energy. Expanded forms of financial support and higher electricity prices have resulted in a large increase in its installed capacity. PV installations are increasingly being ordered by industry and privates, often for installations capacity of several hundred kilowatts. In addition to the advantages, photovoltaic installations also have drawbacks. One of these is that the increase in the voltage in the power grid leads to the exclusion of individual installations from the grid. An important issue in the operation of photovoltaic installations is also their reliability during their lifetime. The reliability of photovoltaic installations depends on the random nature of the cloud cover as well as the material’s mechanical degradations. This paper presents a literature analysis using Citespace software in terms of reliability. A detailed bibliometric analysis has been performed to outline the ma... [more]

The efficiency problem of hydraulic pump units with advanced double structures with constant pressure regulators with different linear characteristics in the case of work in an open supply system is presented in the paper. The main parts of the hydraulic power pack structure and pressure controller functions are described. The equation is given for the calculation of energy losses in particular pumps and the whole multi-pump power pack unit. The difference between the efficiency of particular pumps and the hydraulic pump unit was discussed.

Integration of information communication technology via the Internet of Things devices and sensors can enable an efficient power service for utility providers to consumers in advanced metering infrastructure. Authentication and cryptographic mechanisms protect identity, data security and privacy from unauthorised interception for smart meters to servers. In the last couple of years, many key agreement protocols have been prescribed and deployed to fix those issues. Unfortunately, the deployed protocols did not work inside the same protocols, specifically parameter detection and recognition for session key generation, as they entail high computation time and communication bits overheads. Furthermore, the absence of forward secrecy and user anonymity affects the authentication. Therefore, we have proposed a lightweight identity-based key agreement (LIKA) utilising the Diffie−Hellman cryptography with a trusted authority. It seeks to cover both the security and performance criteria with e... [more]

The successful supply of an economy with coal fuel, for a country that carries out its large-scale extraction and import, is a complex production and logistics problem. Violations of the usual supply scheme in conditions of crises in the energy markets, international conflicts, etc., lead to the problem of simultaneous restructuring of the entire supply scheme. This requires changes in the directions and capacities of domestic production and imports. In this article, the above problem is solved by the economic and mathematical model of production type. The developed model includes subsystems of domestic production and import supply. The results of modeling economy supply with thermal coal for different values of demand are given. The model was used to determine the amounts of coal production for Ukraine with the structure of the coal industry of 2021 and under the condition of anthracite consumers’ transformation to the high volatile coal. Simulations have shown that eliminating the us... [more]

The paper reports on research focused on the use of largely available carbonaceous materials, such as graphite, carbon black and chars, as thermoelectric materials for micro-generation at high temperature. The key feature is the possibility to ignite the thermoelectric device to self-sustain electric generation. The results of the tests performed with such materials, under both cold and hot conditions, showed that a significant change of the electromotive force, with absolute increase up to three orders of magnitude, occurred under hot conditions with flame irradiation, achieving measured values of electromotive force up to 55 mV, in the best case. Monoliths based on biomass chars and covered with a layer of gunpowder gave rise to similar variation of the Seebeck coefficient, as the case of the flame exposed samples. This result confirms the basic idea of the investigation and the possibility of generating an electrical peak in a self-sufficient combustion thermoelectric device with po... [more]

The low permeability of coal seams has always been the main bottleneck restricting coalbed methane drainage. In this paper, a coal seam anti-reflection technology with solid-propellant blasting was proposed, and the composition and proportion of the solid propellants were determined based on the principle of oxygen balance. The authors designed a solid-propellant blasting damage fracture experiment of simulation coal, tested the impact pressure on a blast hole wall, measured the ultrasonic wave velocity, explosive strain and crack propagation velocity, and then revealed the blasting damage fracture process and mechanism of coal based on the experimental results and damage fracture mechanics theory. The history curve of impact pressure time can be divided into three processes including the slow pressurization process, dramatic increase process, and nonlinear pressure relief process. The pressure distribution along the whole blasting hole was uneven, and the peak pressure was relatively... [more]

The current situation in the energy market contributes not only to the sales growth of photovoltaic panels (PV) but also to the intense search for possibilities for its improvement. The purpose of this research was to develop a model to determine, where possible, the most beneficial modifications to improve products. The model used combination techniques, i.e., the SMARTER method, brainstorming (BM), the 7 ± 2 rule, questionnaire, ant colony optimization (ACO), and importance-performance analysis (IPA). In addition, an algorithm supporting ACO was proposed in the MATLAB program. The test was carried out on PV and showed that it is possible to determine the way of product (PV) improvement by determining a sequence of modifications for product criteria states while simultaneously considering customers’ expectations. It was shown that each state of the short-circuit electricity and peak power was satisfactory for customers. It was necessary to modify the maximum current and idle voltage.... [more]

To design an efficient ground source heat pump (GSHP) system, it is important to accurately measure the thermophysical parameters of the geotechnical layer. In the current study, a borehole is tested in detail using a combined thermal response test system (CTRTS) based on a distributed optical fiber temperature sensor (DOFTS) and a laboratory test. Real-time monitoring of the stratum temperature according to depth and operation time and the geothermal profile and thermal conductivity of each stratum are obtained. The results show that the undisturbed ground temperature is 10.0 °C, and the formation temperature field within 130 m can be divided into variable temperature formation, constant temperature formation (9.13 °C), and warming formation (geothermal gradient is 3.0 °C/100 m). The comprehensive thermal conductivity of the region is 1.862 W/m·K. From top to bottom, the average thermal conductivity of silty clay, mudstone, argillaceous siltstone, and mudstone is 1.631 W/m·K, 1.888 W/... [more]

Seeking effective energy technology has become a herculean task in today’s world. Sodium-ion batteries play a vital role in the present energy tech market due to their entrancing electrochemical properties and this work is a breakthrough for developing sodium-ion batteries. As per recent reports, the preparation of anode materials seems to be very tedious in the realm of sodium-ion batteries. To remedy these issues, this work enlightens the preparation of hard carbon (HC) derived from coconut sheath (CS) by a pyrolysis process with different activating agents (KOH, NaOH, ZnCl2) and employed as an anode material for Sodium-ion batteries (SIBs). The prepared anode material was characterized for its thermal, structural, functional, morphological, and electrochemical properties. Additionally, the surface area and pore diameter of the as-prepared anode material was studied by nitrogen adsorption and desorption isotherm methods. The coconut sheath-derived hard carbon (CSHC) anode material de... [more]

For the management of fractured large pores in high-water-bearing reservoirs, the general approach is to use transfer dissection and sealing. Conventional regulators have a limited regulating radius and can only produce blocking in the near-well zone, which is not ideal. Deep dissection technology can expand the radius of action and substantially improve the blocking effect. The existing deep-dissection agent system has problems such as high cost and poor effect, which affect its large-scale application. In this paper, to address these problems, a gel-type dissection modifier cross-linking agent was synthesized and optimized in the laboratory using low-concentration polymer, and the factors affecting the final gel formation effect were experimentally studied. The final polymer concentration was chosen to be 1500 mg/L~3000 mg/L, the poly-crossing ratio was 30:1, the pH was controlled at 7−9, and the temperature was controlled at 30−60 °C; the rubber was formed with good shear resistance... [more]

Modern environmental problems are caused by increased energy consumption and the urban heat island effect. Urban noise pollution is another big problem in the Megacities. Ensuring safety with reducing hazards in the urban space is one of the priority tasks of the urban city centers. One solution is the use of green technologies in the construction of office and residential real estate. In this research, we provide the analysis of reducing the noise impact through the use of different green wall systems, such as modular, hydroponic and container, analyzing their benefits and disadvantages in terms of operation and maintenance. After that, we chose hydroponic systems as the most efficient ones and examined different conditions of the system and how these types reduce the noise analyzing absorption coefficient. As a result, we found out that the efficiency of the hydroponic green wall system depends on the humidity of the substrate and the presence of the plants, which confirms the import... [more]

An optimal tilt-angle control based on artificial intelligence (AI control) for tracking bifacial photovoltaic (BPV) systems is developed in this study, and its effectiveness and characteristics are examined by simulating a virtual system over five years. Using deep reinforcement learning (deep RL), the algorithm autonomously learns the control strategy in real time from when the system starts to operate. Even with limited deep RL input variables, such as global horizontal irradiance, time, tilt angle, and power, the proposed AI control successfully learns and achieves a 4.0−9.2% higher electrical-energy yield in high-albedo cases (0.5 and 0.8) as compared to traditional sun-tracking control; however, the energy yield of AI control is slightly lower in low-albedo cases (0.2). AI control also demonstrates a superior performance when there are seasonal changes in albedo. Moreover, AI control is robust against long-term system degradation by manipulating the database used for reward setti... [more]

Chemical looping combustion (CLC) is one of the most advanced technologies allowing for the reduction in CO2 emissions during the combustion of solid fuels. The modified method combines chemical looping with oxygen uncoupling (CLOU) and in situ gasification chemical looping combustion (iG-CLC). As a result, an innovative hybrid chemical looping combustion came into existence, making the above two technologies complementary. Since the complexity of the CLC is still not sufficiently recognized, the study of this process is of a practical significance. The paper describes the experiences in the modelling of complex geometry CLC equipment. The experimental facility consists of two reactors: an air reactor and a fuel reactor. The paper introduces the fuzzy logic (FL) method as an artificial intelligence (AI) approach for the prediction of SO2 and NOx (i.e., NO + NO2) emissions from coal and biomass combustion carried out in air-firing; oxyfuel; iG-CLC; and CLOU conditions. The developed mod... [more]

This paper explores gender dimensions of the energy transition in the European Union (EU). The EU has set out its ambitions for an equitable transition to clean secure energy. It has also set out it objectives for gender equality. In this paper, I implement a systematic literature review to explore the intersection of gender issues with the energy transition in the EU. There is little peer reviewed literature in this area. Analysis of academic papers shows most focus on social science rather than technical or engineering problems. A critical review of the grey literature including EU policies and reports shows that there is a disconnect between EU gender equality and clean energy plans and that gender has yet to be mainstreamed into the EU energy transition. This review identifies opportunities to mainstream gender into EU energy policies by linking to EU gender equality objectives, and connecting to gender-energy research themes.

Hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) is regarded as the bridge between bio-refinery and the traditional petroleum industry. In recent years, non-precious metal-based catalysts for LA hydrogenation to GVL have attracted much attention owing to their low cost and high efficiency. Metal-involving catalytic hydrogenation of LA is the rate-determining step in the production of GVL, and thus the active site structure of metal-based catalysts governs the overall catalytic performance. Herein, non-precious metal-based catalytic systems including Cu, Zr, Co and Ni are classified into single metal (M = Ni, Cu and Co), bimetallic (Cu−Ni, Ag−Ni, Cu−Co and Co−Zn), metal-heteroatom (M−O and M−N) and heterostructured (CePO4/CoP2 and Ni/NiO) catalysts according to the type of active site structure. The correlation of active site structure with catalytic activity is discussed emphatically, and its relationship with stability is also referred to in terms of strong metal−support... [more]

Metal oxide surge arresters (MOSAs) are a popular solution for dealing with overvoltages due to lightning and switching in power distribution networks. As a result, a MOSA’s performance and longevity have a significant impact on the quality of energy and the frequency of outages. A MOSA performance is determined by several elements such as leakage current, partial discharge, and thermal image measured in various ways. In this study, different techniques for diagnostic and condition monitoring of MOSAs are discussed, and each method’s advantages and disadvantages are investigated. Additionally, the results of practical tests on two 20 kV healthy and degraded MOSAs are investigated and compared.

This paper presents the results of investigations into modeling the DC and dynamic characteristics of an alkaline electrolyzer. A model of the device under consideration is proposed in the form of analytical relationships in which the coefficients depend on the concentration of the potassium hydroxide solution contained in the electrolyzer under consideration. The correctness of the proposed model is verified by comparing the calculated and measured current−voltage characteristics and the dependence of the module of the impedance of the electrolyzer on the frequency obtained at different values of the electrolyte concentration. The dependence of the time needed to produce a given portion of hydrogen on the supply current and the electrolyte concentration is also presented. Good compliance with the calculation and measurement results is obtained over a wide range of voltage and current, frequency, and concentration of the electrolyte.