The production of electricity from photovoltaic (PV) systems is one of the significant opportunities for novel renewable energy sources. The PV systems can provide energy with minimum environmental harm; however, the usage of this energy source becomes strongly dependent on a wide range of social, economic, and technical factors. Based on the growing demand for renewable energy sources, the aim of the work focuses on the socio-economic analysis of possibilities of producing electricity from photovoltaic installations up to 10 kW in Poland. Based on expert research, the factors influencing energy production from PV systems were assessed based on factor three analysis (level II with 5 factors, level III with 15 factors). Using the expert-mathematical method, a hierarchy of economic, technical, and social factors of PV-based energy production was evaluated. The analysis of socio-economic factors indicated that the greatest impact on the PV systems development in Poland depends on energy p... [more]

Green hydrogen production, i.e., produced on a CO2-neutral basis through the electrolysis of water employing renewable electricity, has attracted increasing attention. The electricity required is generated from Renewable Energy Sources (RES), for example, wind energy, hydropower, or solar energy. Since neither the process of production nor the end products of H2 and O2 are harmful to the environment, green hydrogen is climate neutral. Developing electrolysis technology is, therefore, a research topic to follow. Anion Exchange Membrane (AEM) Water Electrolysis (WE) is an innovative technology that couples the advantages of the more mature technologies of Proton Exchange Membrane (PEM) and conventional alkaline electrolysis, with the potential to eliminate the drawbacks of both. AEMWE technology is in an evolutionary stage and involves more investigation on several research topics, such as membrane and catalyst development and stability, as well as alternative feeding solutions that do n... [more]

The world’s technological and economic advancements have led to a sharp increase in the demand for electrical energy. Saudi Arabia is experiencing rapid economic and demographic growth, which is resulting in higher energy needs. The limits of fossil fuel reserves and their disruption to the environment have motivated the pursuit of alternative energy options such as wind energy. In order to regulate the power system to maintain safe and dependable operation, projections of current and daily power generation are crucial. Thus, this work focuses on wind power prediction and the statistical analysis of wind characteristics using wind data from a meteorological station in Makkah, Saudi Arabia. The data were collected over four years from January 2015 to July 2018. More than twelve thousand data points were collected and analyzed. Layout and wake effect studies were carried out. Furthermore, the near wake length downstream from the rotor disc between 1 and 5 rotor diameters (1D to 5D) was t... [more]

Due to the uneven temperature field and temperature gradient introduced by an efficient cooling structure, the analysis of the stress field is necessary. In this study, the cooling characteristics and stress characteristics such as the thermal stress and thermomechanical stress of an impingement/effusion cooling system were investigated by employing a fluid−thermal-structure coupling simulation method. The effects of film hole injection angle (30°−90°) and blowing ratio (0.5−2.0) were studied. The results showed that the film hole shape and the non-uniform temperature field introduced by the cooling structure had a great influence on the stress field distribution. With the increase in the blowing ratio, not only the overall cooling effectiveness of the cooling system increased, but the maximum thermal stress and thermomechanical stress near film holes also increased. The cases with a smaller inclination angle could provide a better cooling performance, but caused a more serious stress... [more]

The use of greywater reduces the consumption of many resources and is an effective tool for achieving Sustainable Development Goals. In order to assess the rationality of its use as an alternative source of energy and water in buildings, a holistic literature review was carried out based on a bibliometric analysis of publications in these fields. The main bibliographic source was the Web of Science database. This review contributed to a better understanding of the analyzed research field. It also revealed trends in greywater energy recovery and recycling research, indicating that these are developing fields. In recent years, there has been a marked increase in the number of publications on the most popular ways of using greywater in buildings, with the territorial scope of research carried out in the greywater recycling domain being considerably larger than research on greywater energy recovery. The analysis revealed poor cooperation between different universities, especially in the fi... [more]

Challenges in utilising fossil fuels for generating energy call for the adoption of renewable energy sources. This study focuses on modelling and nowcasting optimal tilt angle(s) of solar energy harnessing using historical time series data collected from one of South Africa’s radiometric stations, USAid Venda station in Limpopo Province. In the study, we compared random forest (RF), K-nearest neighbours (KNN), and long short-term memory (LSTM) in nowcasting of optimum tilt angle. Gradient boosting (GB) is used as the benchmark model to compare the model’s predictive accuracy. The performance measures of mean absolute error (MAE), mean square error (MSE), root mean square error (RMSE) and R2 were used, and the results showed LSTM to have the best performance in nowcasting optimum tilt angle compared to other models, followed by the RF and GB, whereas KNN was the worst-performing model.

In this article, a novel methodology is proposed by utilizing a technique which, in light of the change in the African vulture optimization known as Sine Cosine, adopted an African vulture optimization algorithm (SCaAVOA)-based tilt integral derivative (TID) regulator for the load frequency control (LFC) of a five-area power system with multi-type generations. At first, the execution of the Sine Cosine-adopted calculation is tried by contrasting it with the standard AVOA calculation while considering different standard benchmark functions. To demonstrate the superiority of the proposed SCaAVOA algorithm, the results are contrasted using different standard approaches. In the next stage, the proposed method is used in a five-area thermal power system and is likewise applied to a five-area, ten-unit system comprising different conventional sources as well as some renewable energy sources. The performance analysis of the planned regulator is completed for various system boundaries and load... [more]

In the case of microgrid (MG) systems, the choice of the right configuration plays a vital role to meet grid/load necessities when integrating low voltage, non-linear and highly sensitive (to environmental conditions) power sources such as solar PV modules, batteries and supercapacitors (SCs), etc. In the case of MG systems, the choice of the right configuration and the appropriate type of power converters in any application can have a significant impact on the optimum performance. Numerous architectures have been proposed for the integration of various energy sources to achieve optimum performance. A large number of research articles have been published in these areas. In this article, the detailed organization of various architectures based on the arrangement of various sources and detailed analyses is presented along with a discussion on those architectures. Moreover, the suitability of all the reviewed architectures based on driving factors such as (a) high conversion gain, (b) goo... [more]

This study follows on from the work on the urban climate of Sfax and its energy repercussions. The spatial configuration of the urban heat island (UHI) and the spatial distribution of the thermal comfort indices, the heat index (HI), the universal thermal climate index (UTCI) and the temperature humidity wind index (THW), resulting from the car survey method, essentially show the impact of land use and the distance from the coastline on the spatial distribution of air temperatures. A maximum difference of 7 °C between the city centre and the countryside is measured in very hot summer weather. During the night phase, the apparent temperatures are oppressive, particularly in the city centre, where HI and THW comfort indices exceeding 40 °C were calculated. Compared to the HI and UTCI, the THW demonstrates a much stronger variation due to the influence of wind between open areas and the downtown area. The intensity of thermal discomfort decreases as one moves towards the rural area (−15 °... [more]

Ammonia, as an alternative fuel for internal combustion engines, can achieve nearly zero carbon emissions. Although the development of the pure ammonia engine is limited by its poor combustion characteristics, ammonia−hydrocarbon mixed combustion can effectively improve the combustion of ammonia fuel. With the increase in the ammonia fuel proportion in the fuel mixture, a large number of nitrogen oxides (NOX) and unburned ammonia may be discharged, which have a poor impact on the environment. In this study, the performance of selective catalytic reduction (SCR) aftertreatment technology in reducing NOX and ammonia emissions from ammonia−diesel dual-fuel engines was investigated using simulation. A good cross-dimensional model was established under the coupling effect, though the effect of a single-dimensional model could not be presented. The results show that when the exhaust gas in the engine cylinder is directly introduced into the SCR without additional reducing agents such as urea... [more]

Tower cost makes up an important part in the whole wind turbine construction especially for offshore wind farms. The main method to reduce tower cost is to reduce tower weight by optimum design. This paper proposes a two-level optimization criterion method for the optimal design of steel conical tower considering different structural reliability and uncertainty, along with the discreteness of design variables such as tower thickness and bolt type. In the first level, the tower shell geometry can be obtained by section design method; in the second level, bolted connections and flanges are designed based on the results of the first level. Then, summarized analysis and iterative calculation is performed to obtain optimum tower design with constant strength and rigidness. This method will play an important role in offshore customized turbine design.

In response to the rising importance of the climate agenda, many countries have restructured their electricity markets to facilitate the utilization of renewable energy. China is an interesting case because it has expanded its utilization of wind and solar energy with unmatched speed. This review starts with an analysis of the 2002 reforms that uncoupled electricity production from transmission. The investigation covers the period leading up to the 2022 proposal, which aimed to build a nationally integrated electricity market. The analysis suggests that a careful alignment of incentives for key market players to produce and consume renewable energy is vital during the process of energy transition. The introduction of feed-in tariffs in 2009 for wind energy, which were subsequently extended to solar energy, stimulated a high growth in installed capacity. However, a high electricity curtailment rate resulted. Since 2018, the Chinese government has resorted to curtailment caps and renewab... [more]

Climate change and the depletion of fossil fuels make it urgent to find an alternative to oil-based fuels, especially in machines powered by internal combustion engines. Biomass is currently a poorly used source of energy and meets the necessary conditions to replace a large part of oil-based fuels. However, current engines cannot burn solid biomass and a specific engine needs to be developed. This work proposes the thermodynamic cycle of a biomass-fueled internal combustion engine. The cycle is significantly different from the Otto cycle, since compression and heat absorption occur simultaneously, in a single stage. Since it is not possible to find a function that relates pressure to volume at this stage, an approximate method is proposed to solve the cycle without resorting to numerical methods. The results show that the maximum pressure and temperature of a biomass-fueled engine cycle are somewhat higher than those of the equivalent Otto cycle. However, more significantly, the cycle... [more]

One aspect of the competitiveness of electric and plug-in hybrid vehicles is the ability to recharge batteries quickly. Ideally, this process would take no longer than it takes to refuel vehicles powered by conventional fuels. The term fast charging is generally used to refer to alternating current (AC) charging of more than 22 kW and direct current (DC) charging often referred to as fast or ultra-fast charging at high power. Currently, fast charging points are located within the public charging infrastructure, mainly along highways. The purpose of this paper was to analyze the availability of existing charging infrastructure equipped with fast charging points for electric vehicles in European Union countries. In addition, the paper discusses EU policy in terms of zero-emission vehicles and technical issues related to charging infrastructure. Based on a review of the current state of charging infrastructure and plans for its development in light of the EU Green Deal for Europe regulati... [more]

Smart Battery Chargers (SBCs) implementing grid-forming (GFM) control strategies are a promising solution to provide voltage and frequency support, increasing the grid reliability. Typically, GFM studies consider inverters with high DC-link capacitance. Therefore, there is a research gap in two-stage DC-AC converters with small DC-link capacitance implementing GFM strategies. This article proposes a novel approach to implement a GFM control strategy along with active power decoupling (APD) in an isolated, single-phase, electrolytic-capacitor-free two-stage DC-AC structure. The structure is composed of a voltage source inverter (VSI), DC-linked by film capacitors, with a dual-active-bridge series-resonant (DABSR) DC-DC converter. High DC-link ripple is allowed and managed by the APD. Hence, electrolytic capacitors are avoided, increasing the converter lifetime. In the proposed approach, the VSI implements the GFM strategy, operating in the four quadrants of the active and reactive power... [more]

With the rapid growth in industrial development, there is a particular need for new environmentally balanced energy source utilization. Ethanol produced from biomass, especially lignocellulosic waste products, represents an attractive, sustainable energy source for fuel production. Until now, in Poland, bioethanol has been produced from edible plants containing sugars susceptible to fermentation. Due to the growing technical and economical needs for alternative biomass source utilization, in the present work, an attempt has been made to identify the most cost-effective strategy to analyze ethyl alcohol production from different lignocellulose sources. The concept of an installation for the first and second stages of bioethanol production was proposed. All of the most relevant elements of the bioethanol production cost analysis were identified and characterized. Cost analyses of all important production process elements showed their relative effects on the production cost and potential... [more]

Perovskite solar cells technology is one of the most advanced and fascinating technologies in the field of photovoltaics due to its low-cost processing and delivering efficient power conversion efficiencies. The ability to become transparent is another prolific property of the perovskite solar cells, which this property has been tried to be exploited in recent times by researchers to serve the environmental and energy needs of human beings. Using this transparency and enabling semitransparent perovskite solar cells (ST-PSCs) to be placed on the windows and rooftops of buildings will reduce room temperature along with fulfilling certain requirements of power needs. This review pays attention to the recent developments in the semitransparent perovskite solar cells from the perspective of the structure of ST PSCs, electrodes and others.

Heteroatom doping is an effective strategy to regulate electrocatalysts for the oxygen evolution reaction (OER). Nonmetal heteroatoms can effectively engineer geometric and electronic structures and activating surface sites of catalysts due to their unique radius and the electronegativity of nonmetal atoms. Hence, the surface geometric and electronic structure and activity of nonmetal atoms (X, X = B, C, N, O, P)-doped Ni3S2 (X-Ni3S2) were studied to screen high-performance Ni3S2-based OER electrocatalysts through density functional theory calculation. Theoretical results demonstrated that dopants in X-Ni3S2 can alter bond length and charge of surface, modify active sites for intermediates adsorption, and adjust the theoretical overpotential. Among all dopants, C can effectively modulate surface structure, activate surface sites, weaken the adsorption of key intermediates, decrease theoretical overpotential, and enable C-Ni3S2 with the best theoretical OER activity among all X-Ni3S2 wi... [more]

Multi-fractured horizontal well (MFHW) technology is a key technology for developing unconventional reservoirs, which can generate a complex fracture network called a stimulated reservoir volume (SRV). Currently, there are many relative analytical models to describe the fluid seepage law, which are not suitable for volcanic reservoirs as of yet. The reasons are as follows: (1) due to the development of natural fractures, multi-scaled flow (matrix, natural fractures, SRV) should be considered to characterize MFHW flow in volcanic reservoirs; (2) non-Darcy flow and stress sensitivity should be considered simultaneously for seepage in volcanic reservoirs. Thus, this paper presents a novel MFHW analysis model of volcanic reservoirs that uses a multi-scale dual-porosity medium model and complex flow mechanisms. Laplace transformation, the Duhamel principle, the perturbation method and Stehfest numerical inversion are employed to solve the model to obtain dynamic pressure response curves. Th... [more]

It is well known that all real automatic control systems (ACS) are significantly nonlinear systems. Along with this, in engineering analysis the simplifications of their mathematic description, that is, linearization, are inevitable. These simplifications naturally introduce errors into engineering calculations. For the most complicated calculation of stability conditions, these errors can be very significant, since they lead to not only incorrect forecast of the ACS condition but also to the operating inability of the designed ACS. Most often, engineers simplify nonlinear structures in their calculations. In other words, they linearize these structures according to one of the numerous approaches which have been developed over 100 years. Calculation methods for linear ACS, in particular the Nyquist criterion, can be applied to the already linearized structure for the calculation of ACS stability condition. In this article, the authors suppose that for electromechanical and power ACS it... [more]

Smart and mechanically flexible energy harvesting/storage devices are attractive for the immensely growing electronic, automobile, medical, and aerospace markets. The leading challenges with current devices are their limitations regarding installation on curvy design, high-manufacturing cost, and lower production rate. Therefore, new design strategies in terms of new materials, cost, and ability to scale up fabrication are imperative to meet the contemporary and future demands of these fast-growing markets. Flexographic printing is one of the newest technologies that promises cost-effective energy devices with better energy harvesting and high storage performance. Current knowledge, selection of suitable materials, and methods of flexographic printing for solar cell and battery construction are reviewed and summarized in this paper in comparison to existing printing technologies. The main purpose of this review is to provide a comprehensive idea of flexographic printing for energy devi... [more]

This study determines and presents the capital and operating costs imposed by the use of CO2 capture technologies in the refining and petrochemical sectors. Depending on the refining process and the CO2 capture method, CO2 emissions costs of EUR 30 to 40 per ton of CO2 can be avoided. Advanced low-temperature CO2 capture technologies for upgrading oxyfuel reformers may not provide any significant long-term and short-term benefits compared to conventional technologies. For this reason, an analysis was performed to estimate the CO2 reduction potential for the oil and gas industries using short- and long-term ST/MT technologies, was arriving at a reduction potential of about 0.5−1 Gt/yr. The low cost of CO2 reduction is a result of the good integration of CO2 capture into the oil production process. The results show that advanced gasoline fraction recovery with integrated CO2 capture can reduce the cost of producing petroleum products and reduce CO2 emissions, while partial CO2 capture ha... [more]

Steel production is one of the biggest emitters of greenhouse gas in the industrial sector with about 8% of total global CO2 emissions. Although the majority of emissions can be attributed to primary steel production, there is also potential for reducing CO2 emissions in downstream steel processing. Large industrial furnaces, which are necessary for heating steel, are currently primarily fired with natural gas and by-product gases from primary steel production, offering great potential for heat recovery measures from exhaust gases. However, switching to alternative climate-neutral fuels could change this potential and thus jeopardize the economic viability of heat recovery measures. In the present work, it was therefore examined to what extent a change in energy sources in industrial furnaces affects the potential use of heat recovery in steel processing. For this purpose, an optimization model was used that takes into account heat recovery by means of direct heat transfer, heat pumps... [more]

Global gas markets are changing as natural gas (NG) is replaced by biomethane. Biomethane is produced by upgrading biogas, which can have a molar concentration of methane to over 98%. This renewable energy has been injected into the pipeline networks of NG, which offers the possibility to increase its usage in industrial and residential applications. However, the expectation of the increase in biomethane proportion on the NG grids could increase the fluctuations on the composition of the NG−biomethane mixture in amplitude and frequency. In this context, the injection of biomethane into the existing network of NG raises a discussion about the extent to which variations in gas quality will occur and what permissible limits should exist, as variations in combustion characteristics can affect the operation of the combustion processes, with consequences for consumers, distributors and gas producers. This study describes a gas quality analysis with regard to the use of biomethane in industri... [more]

In recent decades, electronic devices have tended towards miniaturization, which necessitates the development of new cooling systems. Droplet cooling on a heated wall is effectively used in power devices with high heat flux densities. The use of a surfactant leads to an increase in the diameter of the wetted spot and the rate of droplet evaporation. Despite the wide interest and numerous works in this area, there are still unexplored questions regarding the influence of surfactant and wall temperature on convection, of nonisothermality, and of the decrease in the partial pressure of vapor with increasing surfactant concentration. This work experimentally studies the effect on the rate of droplet evaporation of wall temperature in the range 20−90 °C and of the concentration of surfactant in an aqueous solution of sodium lauryl sulfate (SLS) from 0 to 10,000 ppm. It is shown for the first time that an inversion of the evaporation rate related to the droplet diameter occurs with increasin... [more]