Aiming at the capture and conversion of multidirection wave energy, a multifreedom direct-drive wave-energy converter (WEC) based on a parallel mechanism is studied. The dynamic model of WEC was conducted based on force analysis and hydrodynamic theory, and the inverse kinematic solutions of each branch chain of the mechanism were obtained following the space vector method. Furthermore, the kinetics response of the linear generator branch chain was obtained. Moreover, the influence on the capture efficiency of the device’s geometric structure scale was investigated under different sea conditions. To evaluate the performance of the WEC, a linear generator model was simulated and analyzed by COMSOL Multiphysics. A laboratory prototype was manufactured. The test results indicated that the multifreedom device can achieve better power conversion performance than traditional single degree of freedom (DOF) devices. This study provides ideas for the design and development of large multi-DOF wa... [more]

In the current work, the exact analytical expression of the current−voltage characteristics, which are given in terms of the LambertW function, is used to extract the physical parameters of organic and inorganic Schottky barrier diodes (SBDs). The extraction is achieved by a variety of methods using the experimental I−V characteristics. The organic SBD is based on a Poly (3-hexylthiophene-2,5-diyle) conjugated polymer (P3HT) with Al contact, measured at 300 K. Regarding the inorganic SBDs, one is based on Iridium−Silicon Carbide (Ir−SiC), measured at 300 K, and the second diode is based on Gold−Gallium Arsenide (Au−GaAs), measured at 200 K. The numerical characteristics based on the physical parameters extracted by the presented methods are in good agreement with the experimental data. The determination coefficient of the modeling methods for the three SBDs is higher than 99.99%.

The motive for the functioning of enterprises in the market economy is the maximization of benefits by achieving positive financial results with the minimum possible involvement of capital. The positive results achieved are perceived very positively by the stakeholders. To achieve this, it is necessary to carry out reorganization processes (mergers and acquisitions) within capital groups, which are perceived as necessary (positive) measures. These phenomena have been observed in the energy sector for many years, and the years 2010−2021 were adopted as the research period. The aim of this article is to attempt to answer the question of whether the multi-energy concern is the result of activities carried out in light of the 2030 Agenda. The effect of merging the entities is capital concentration. This fact has been verified by reviewing changes in the structures of capital groups in the energy sector against the background of the largest mergers and acquisitions in Poland in terms of val... [more]

District heating systems are almost always located in densely populated urban areas where various heat sources are available, such as cooling and refrigeration systems in supermarkets, shopping malls, and power transformers. These urban sources often have a large share of waste heat, which is usually emitted into the environment. This waste heat could be used to partially cover the thermal load in district heating systems. The biggest challenge for their integration is the spatial distribution of urban heat sources in relation to the existing heat network and the temporal distribution of the availability of waste heat energy throughout the year. In this paper, we have developed an economic assessment model for the integration of urban heat sources into existing district heating systems. By the hourly merit order of waste heat utilization technologies based on pinch analysis, we have defined the most suitable integration of urban heat sources into existing district heating systems. Diff... [more]

Dynamic programming (DP) is currently the reference optimal energy management approach for hybrid electric vehicles (HEVs). However, several research concerns arise regarding the effective application of DP for optimal HEV control problems which involve a significant number of control variables, state variables and optimization constraints. This paper deals with an optimal control problem for a full parallel P2 HEV with constraints on battery state-of-charge (SOC), battery lifetime in terms of state-of-health (SOH), and smooth driving in terms of the frequencies of internal combustion engine (ICE) activations and gear shifts over time. The DP formulation for the considered HEV control problem is outlined, yet its practical application is demonstrated as unfeasible due to a lack of computational power and memory in current desktop computers. To overcome this drawback, a computationally efficient version of DP is proposed which is named Slope-weighted Rapid Dynamic Programming (SRDP). Co... [more]

The internal energy (U-energy) conversion to free energy (F-energy) and energy dissipation (S-energy) is a basic process that enables the continuity of life on Earth. Here, we present a novel method of evaluating F-energy in a membrane system containing ternary solutions of non-electrolytes based on the Kr version of the Kedem−Katchalsky−Peusner (K−K−P) formalism for concentration polarization conditions. The use of this formalism allows the determination of F-energy based on the production of S-energy and coefficient of the energy conversion efficiency. The K−K−P formalism requires the calculation of the Peusner coefficients Kijr and Kdetr (i, j ∈ {1, 2, 3}, r = A, B), which are necessary to calculate S-energy, the degree of coupling and coefficients of energy conversion efficiency. In turn, the equations for S-energy and coefficients of energy conversion efficiency are used in the F-energy calculations. The Kr form of the Kedem−Katchalsky−Peusner model equations, containing the Peusn... [more]

Enterprises’ green technology innovation is critical to achieving the “win-win” of enterprise competitiveness and environmental protection. The impact of environmental regulation on green technology innovation by enterprises has been widely considered, but the conclusion has not yet been determined, and needs to be studied in detail. To this end, we studied the impact of pollution charge policy on different types of green technology innovation by industrial enterprises in China. We found that (1) the impact of pollution charges on most types of green technology innovation by enterprises has increased significantly over time; (2) the pollution charge policy has a certain inhibition effect on the end-of-pipe technology innovation, but can promote the process improvement of reducing industrial wastewater emissions; (3) there is a U-shaped relationship between the pollution charges and some green technological innovation (e.g., emission intensity of SO2, industrial wastewater emission inte... [more]

The industry related to electric vehicles (EVs) has seen a substantial increase in recent years, as such vehicles have the ability to significantly reduce total CO2 emissions and the related global warming effect. In this paper, we focus on the problem of allocating EVs to charging stations, scheduling and pricing their charging. Specifically, we developed a Mixed Integer Program (MIP) which executes offline and optimally allocates EVs to charging stations. On top, we propose two alternative mechanisms to price the electricity the EVs charge. The first mechanism is a typical fixed-price one, while the second is a variation of the Vickrey−Clark−Groves (VCG) mechanism. We also developed online solutions that incrementally call the MIP-based algorithm and solve it for branches of EVs. In all cases, the EVs’ aim is to minimize the price to pay and the impact on their driving schedule, acting as self-interested agents. We conducted a thorough empirical evaluation of our mechanisms and we ob... [more]

Due to the voltage drop of the line impedance, power-transfer deviation occurs in the interlinking converter (IC) of hybrid microgrids. In this paper, an IC control strategy in hybrid microgrids is proposed, which can estimate the line resistance precisely. Moreover, the proposed method can easily realize accurate power transmission between sub-grids and maintain the power balance of hybrid microgrid. Firstly, one specified small signal is injected into the IC at the AC bus of the distributed generation so as to estimate the line impedance. The frequency of the injected small signal is highly relevant to the AC bus voltage. As a result, the IC can accurately detect its line impedance by extracting the injected small signal frequency with a filter and phase-lock-loop (PLL) without communication. Secondly, with the line impedance estimation, the voltage drop on the line can be compensated with local information of the IC, and consequently, accurate power transfer can be realized. Finally... [more]

The Ukrainian renewable energy sector has demonstrated a significant increase in its renewable power capacity, especially for solar and wind power plants. Decommissioning the end-of-life equipment in Ukraine has not yet taken place, but it is only a matter of time. With this in mind, this paper assesses the quantities and the market values of the materials that could potentially be recovered from used solar and wind power plants, and it estimates the impact of their decommissioning on employment in Ukraine. It has been estimated that approximately 8.9 GW of solar power plants, and 3.6 GW of wind power plants, will be decommissioned from 2044 to 2059, and that the cost of the raw materials recovered could reach EUR 421.4 million and EUR 124.6 million in 2021 prices, respectively, compared to the decommissioning costs of EUR 240.1 million and EUR 49.1 million, respectively. Decommissioning renewable power plants will require the creation of new jobs, including 11.6 thousand in the solar... [more]

The present article presents an analysis of the potential application of 3D printing in the critical infrastructure system. An attempt has been made to develop case studies for selected critical infrastructure areas, particularly with reference to the area of energy supply. The need for 3D printing applications is identified based on expert research in the energy industry. It identifies the application schemes determined by the technical and logistical possibilities associated with 3D printing in its broadest sense. A review of additive technologies with a view to their application in selected phases of critical infrastructure operation, including in crisis situations, is also carried out. Furthermore, a methodology for incorporating 3D printing into the existing critical infrastructure system is proposed. As a result, the following research hypothesis is adopted: the use of 3D printing can be an important part of measures to ensure the full functionality and efficiency of critical inf... [more]

It is essential for the electricity sector to analyze and determine the distribution capacity throughput and apply new methods aimed at increasing the capacity of the transmission system. Consequently, the transition to modern electricity networks is two-sided, i.e., involving technological and social modifications. The demand response (DR) redistributes consumption away from peak times when grid load and costs are the highest. It incentivizes customers to use electricity when supply is high and inexpensive due to various market mechanisms. The present DR policy proposals stress the importance of fostering behavioral change through competitive pricing and customer participation in reducing carbon emissions and implementing smart energy solutions (including monitoring tools, such as smart meters and applications). The internet of things (IoT) has been applied to ensure adaptive monitoring of energy consumption and cost-effective and adequate demand-side management (DSM). The article is... [more]

This paper aims to determine cost optimality between heating, ventilation and air conditioning (HVAC) systems operating with air to water heat pumps (AWHP) and water to water heat pumps (WWHP). The analysis is performed for a certain number of heat pump units with fixed and variable capacity made by four manufacturers available on European market. Simulations are performed in Trnsys software. The results show that heat pump partial load efficiency should not be neglected in analysis of application while the difference in energy consumption and costs can be up to 17%. The requirement for performing analysis on a wider range of units is indicated, especially when heat pump systems with different sources are considered. HVAC system with AWHP units with capacity control is a cost optimal solution for case study nursery building operating on the Croatian coast. The application of the photovoltaic (PV) array sized to cover nonrenewable part of electricity consumed in HVAC system has a return... [more]

High-temperature particle receivers are being developed to achieve temperatures in excess of 700 °C for advanced power cycles and solar thermochemical processes. This paper describes designs and features of a falling particle receiver system that has been evaluated and tested at the National Solar Thermal Test Facility at Sandia National Laboratories. These advanced designs are intended to reduce heat losses and increase the thermal efficiency. Novel features include aperture covers, active air flow, particle flow obstructions, and optimized receiver shapes that minimize advective heat losses, increase particle curtain opacity and uniformity, and reduce cavity wall temperatures. Control systems are implemented in recent on-sun tests to maintain a desired particle outlet temperature using an automated closed-loop proportional−integral−derivative controller. These tests demonstrate the ability to achieve and maintain particle outlet temperatures approaching 800 °C with efficiencies betwe... [more]

In different kinds of buried pipelines, L245 and L360 are the most used which are chosen by the China Pipeline Design Institute. For studying the stress and deformation characteristics of buried pipelines with different specifications across faults, this paper established a physical model of cross-fault buried pipelines and a finite element model of pipelines crossing the fault zone, which adopts the finite element method and ANSYS software. The models take pipeline material, soil material, grid division, load application method, and other factors into consideration, concentrating on the nonlinear solution of L245 and L360 buried pipelines under the condition of strike-slip fault soil. The results illustrate that pipelines with larger diameters are more conducive to resisting the stress and deformation caused by faults. Moreover, the strain and dislocation amount of the pipeline increases with the increase of the dislocation amount when a fault occurs. Furthermore, the resistance is op... [more]

The application of traditional well test interpretation methods cannot comprehensively consider characteristics of stress sensitivity and non-Darcy flow for low-permeability composite gas reservoirs, which makes it difficult to obtain real reservoir parameters. Based on the micro-mechanism analysis of stress sensitivity and non-Darcy flow in low-permeability gas reservoirs, the flow motion equation was improved. Thus, a mathematical model was established which belongs to the inclined well in the composite gas reservoir with a conventional internal zone and low-permeability external zone. Applying the finite element method to solve the flow model through Matlab programming, the equivalent pressure point was selected to research the pressure distribution of the inclined well. On this basis, the bottom hole pressure dynamic curve was drawn, the flow process was divided into seven stages, and the parameter sensitivity analysis was carried out. Finally, the advanced nature of the new model... [more]

This article’s focuses of photovoltaic installations, which are becoming more and more popular in Poland and around the world. A short theoretical introduction to photovoltaic cells is presented, and the aim of the research is distinguished. Then, the formulas for the parameters characterizing solar cells are derived. The parameters that determine the highest efficiency of solar cells are specified in the next section. In the experimental part, tests of a selected photovoltaic installation were carried out. Based on the research, we conclude that temperature and sunlight have a significant impact on the efficiency of solar cells.

High-quality titanium dioxide (TiO2 or titania) nanoparticles (TiO2NPs) with tailored morphologies are desirable for efficient photovoltaic applications. In this view, some thin films containing spherical TiO2NPs were prepared on indium tin oxide (ITO) and silicon (Si) substrates from titanium hydroxide Ti(OH)4 using the unified sol-gel, spray and spin coating method followed by thermal annealing at different temperatures (in the range of 200−650 °C). Samples were characterized using various analytical tools to determine the influence of annealing temperatures on their structures, morphologies, and optical and photovoltaic characteristics. A field-emission scanning electron microscope (FESEM) and energy-filtered transmission electron microscopy (EFTEM) images of the annealed films displayed the existence of spherical TiO2NPs of average size in the range of 3.2 to 33.94 nm. XRD analysis of the films showed their amorphous nature with anatase and rutile phase. Optical UV-Vis spectral ana... [more]

Combatting climate change necessitates a substantial global increase in renewable electricity capacity. Many low-income and lower-middle-income countries suffer from unfavorable green financing conditions. Fifteen of these countries possess substantial natural gas reserves. To overcome green financing constraints in such countries, we propose an integrated energy contract that awards a renewable energy project in parallel with an upstream natural gas project to interested energy companies. The state returns from the natural gas project provide a guarantee for renewable energy investments, reducing their associated risks. We conduct Monte Carlo simulations for each of the targeted countries after populating the input parameters for the upstream natural gas and renewable energy projects, including forecasting country-specific natural gas prices. When accounting for 10% of their existing natural gas reserves in the proposed contract, Nigeria, Myanmar, and Indonesia can achieve more than 6... [more]

Considering stability and fabrication cost, 3−4 columns are usually adopted for semi-submersible platform designs. Although increasing the number of columns provides more stability for both floating platform and system as a whole, it is generally not economically viable. In this respect, the present work provides a high-fidelity analysis of semi-submersible platform stability and hydrodynamic response for different design concepts. The number of columns was considered as the main design parameter and was varied from 3−6 columns. The semi-submersible weight was kept constant during the simulation period by changing the column diameter and amount of ballast water. The investigation was carried out using the potential code Orcawave, the results of which were input directly to the engineering tool OrcaFlex. Four different types of semi-submersible platforms with a varying number of columns were tested and compared under extreme environmental conditions in order to ensure their stability an... [more]

Countries’ emission reduction commitments under the Paris Agreement have significant implications for lifestyles. National planning to meet emission targets is based on modelling and analysis specific to individual countries, whereas global integrated assessment models provide scenario projections in a consistent framework but with less granular output. We contribute a novel methodology for translating global scenarios into lifestyle implications at the national and household levels, which is generalisable to any service or country and versatile to work with any model or scenario. Our 5Ds method post-processes Integrated Assessment Model projections of sectoral energy demand for the global region to derive energy-service-specific lifestyle change at the household level. We illustrate the methodology for two energy services (mobility, heating) in two countries (UK, Sweden), showing how effort to reach zero carbon targets varies between countries and households. Our method creates an ana... [more]

The optimal design of a building and city, including the balance of their energy performance, must include requirements from a wide range of areas, especially electrical engineering, informatics, technical equipment of buildings, construction and architecture, psychology and many other fields. It is the optimal design, simulation and modelling that are most reflected in the energy requirements of buildings while meeting the requirements of energy sustainability. The impact of buildings and cities on the environment is crucial and unmistakable. It should be emphasized that an inappropriately (architecturally or technologically) designed building with state-of-the-art control technology will still have worse properties than an optimally designed building without a control system. This inspired us to design a building energy model (BEM) with the implementation of a Smart Grid in a decentralized sustainable energy system, which is a microgrid from renewable energy sources (RES). This inspi... [more]

Owing to the increasing use of electric vehicles (EVs), the demand for lithium-ion (Li-ion) batteries is rising. In this light, an essential factor governing the safety and efficiency of electric vehicles is the proper diagnosis of battery errors. In this article, we address the detection of battery problems by using the intraclass correlation coefficient (ICC) method and the order of cell voltages to enhance EV performance. Furthermore, we propose a framework for diagnosing problems with battery packs, which could be used to detect abnormal behavior. The proposed method calculates ICC values based on the terminal voltages extracted from a caravan battery pack. These ICC values are then used to determine whether the battery has a defect. In addition, the order of cell voltages is used to analyze the causes of faults. Furthermore, we conducted experiments to investigate and evaluate battery cell faults in EVs. The experimental results indicate that the proposed approach can be used to d... [more]

A small prototype of a 5-level single-phase full H-bridge inverter for ocean current applications is presented. The inverter was designed applying level-shift control in pulse-width modulation (LS-PWM), and experimental tests were conducted using a variety of modulation subschemes, including in-phase disposition (IPD), alternate-phase opposition−disposition (APOD), and phase opposition−disposition (POD). The test results were examined for harmonic content and voltage total harmonic distortion (THDV). The results suggest that the inverter presents a viable solution with significant potential for the development of a larger three-phase inverter model that can be used to connect ocean current power sources to the electrical grid.

Accurate characterization of the micro- and nano-pore radius values in a tight sandstone reservoir is the key work to reasonably evaluate reservoir properties. The previous exploration of pore-stitching methods is mainly based on the morphological extension of similar segments. However, few scholars compare and verify the image and non-image stitching methods, so they cannot clarify the application scope of different pore-stitching methods. In this study, the pore structures of eight selected tight sandstone samples were evaluated using high-pressure mercury injection, nuclear magnetic resonance, scanning electron microscope, and the helium porosity test. Then, the C-value fitting, interpolation fitting, and morphological fitting were used to establish high-pressure mercury injection and Nuclear Magnetic Resonance (NMR) pore distribution curves to evaluate the differences among the micro-nano-scale pore radius values determined by the three fitting methods. Finally, the pore radius dis... [more]