Wind energy (WE), which is one of the renewable energy (RE) sources for generating electricity, has been making a significant contribution to obtaining clean and green energy in recent years. Fitting an appropriate statistical distribution to the wind speed (WS) data is crucial in analyzing and estimating WE potential. Once the best suitable statistical distribution for WS data is determined, WE potential and potential yield could be estimated with high accuracy. The main objective of this paper is to propose a novel approach for calculating wind energy potential. For this purpose, the Efficient Global Optimization (EGO) technique was proposed for fitting a statistical distribution to WS data and the performance of the technique was compared with genetic algorithm (GA), simulated annealing (SA), and differential evolution (DE). Performance metrics showed that EGO is providing better estimations compared with GA, SA, and DE. Based on Weibull parameters obtained by using EGO, potential W... [more]

This work presents the synthesis of heat-integrated water networks (HIWNs) by using mathematical programming. A new superstructure is synthesised by combining a water network and a modified heat exchanger network. Based on the proposed superstructure, a mixed-integer nonlinear programming (MINLP) model is developed. The model is solved by using a one-step solution strategy enabling different initialisations and the generation of multiple solutions, from which the best one is chosen. The results show that the proposed model can be effectively used for solving HIWN problems of different complexities, including large-scale problems.

The aim of this paper is to present the results of the Weather Research and Forecasting (WRF) model of solar radiation for moderate climatic zones. This analysis covered the area of northeastern Germany. Due to very unfavorable solar energy conditions in this region for at least 1/3 of the year, we decided to select the dates with the most representative conditions: passing warm fronts, cold fronts, and occluded fronts (two cases each). As the reference, two cloudless conditions during high-pressure situations were chosen. Two different shortwave radiation schemes—Rapid Radiative Transfer Model for general circulation model (RRTMG) and Dudhia—were tested. The obtained results were compared with in situ data measured at Deutscher Wetterdienst (DWD) stations and then with European Medium-Range Weather Forecast reanalysis (ERA5) data. The results showed that for high-pressure situations, the mean correlations with measured data were above 90%. The Dudhia scheme, in addition to the expecte... [more]

In recent decades, works have been published on the Hybrid Renewable Energy System (HRES) to provide available, feasible, and efficient renewable energy systems. Several studies have looked at the efficiency of the systems in terms of sustainability through performance parameters. This study aims at estimating the optimum HRES based on biomass and photovoltaic (PV) using the case study of 94 residential buildings with an electricity demand of 84.5 kWp. The influence of key parameters (global solar irradiation, component efficiencies, fuel consumption, economic convenience) and their impact on the performance and cost of the system is investigated. The optimum system is evaluated by the simulation software HOMER Pro. A single year of hourly data is used to analyze the component performance and the overall system performance. In this work, a mathematical model based on the IEC 61724 standard is used to incorporate numerous performance indicators that are critical for estimating the perfo... [more]

The Kingdom of Saudi Arabia (KSA) is committed to transition its fossil fuel-driven electricity generation to that from renewable energy technologies, such as solar photovoltaic (PV) and wind. The need to reduce greenhouse gas emissions has led it to announce an ambitious target of 40 GW of PV power capacity by 2030. The deployment of such a capacity needs to be augmented with analyses to overcome the challenges faced in terms of the technical capability of the country. This work contributes to this goal by investigating the utilisation of solar photovoltaic PV systems to supply medium-size entities such as universities with clean power, displacing the current fossil fuel power supply. Currently, such considerations are not fully addressed in KSA. The study used the University of Jeddah campus electrical load profile, taking into account future power needs. The methodology encompassed modelling the installation of multi-MW PV systems for the university by considering weather conditions... [more]

In the wake of the United Nation’s Sustainable Development Goals—zero hunger and affordable modern/clean energy for all—many developing countries have taken serious steps in recent years to increase clean energy access for the rural population. The government of Pakistan has similarly made numerous efforts to promote the use of clean energy sources in the rural areas of the country. Therefore, this study examines rural households’ energy choices for cooking and lighting in Pakistan. In doing so, a comprehensive dataset is collected from three different districts of Pakistan between 2020 and 2021, and multivariate probit (MVP) model and Chi-square tests are employed. The Chi-square results indicate that the age, education level, and occupation of the household-head; household size and income; distance to market and wood source; and biogas system ownership are the significant factors affecting cooking choices. The MVP results show that an increase in education level, school-going childre... [more]

This review article discusses the effects of inorganic content and mechanisms on raw biomass and char during gasification. The impacts of the inherent inorganics and externally added inorganic compounds are summarized based on a literature search from the most recent 40 years. The TGA and larger-scale studies involving K-, Ca-, and Si-related mechanisms are critically reviewed with the aim of understanding the reaction mechanisms and kinetics. Differences between the reaction pathways of inorganic matter, and subsequent effects on the reactivity during gasification, are discussed. The present results illustrate the complexity of ash transformation phenomena, which have a strong impact on the design of gasifiers as well as further operation and process control. The impregnation and mixing of catalytic compounds into raw biomass are emphasized as a potential solution to avoid reactivity-related operational challenges during steam and CO2 gasification. This review clearly identifies a gap... [more]

The use of a Doubly Fed Asynchronous Machine (DFAM) provides attractive characteristics and offers operational flexibility in many variable speed generation applications, such as in a hydroelectric pumped storage plant. In a variable speed hydroelectric pumped storage plant, the start-up process of DFAM is identical to the conventional singly fed asynchronous machine, wherein a significant amount of energy is wasted. This paper introduces an energy-efficient start-up strategy in DFAM based hydroelectric pump-turbine. The back-to-back voltage source converter connected to the rotor side is amenable for speed control (real power), braking (regenerative/dynamic), and starting the unit. Further, in this starting technique, the stator circuit of the machine is injected with a low voltage DC supply at starting instead of short-circuiting the windings. This DC injection reduces the slip losses and cuts down the magnetizing current requirement. The magnitude of the required DC supply is estima... [more]

Wireless power transfer (WPT) is currently sparking more attention towards the application of wireless charging for mobile devices and electric vehicles [...]

The automotive market has been developing very dynamically recently. Contemporary trends focus on the development of the so-called intelligent vehicles, often combined with modern technology and supporting systems. Cars with a large scope of operation in terms of driving autonomy can increasingly be found. These types of solutions can lead to changes in production processes through the emergence and growing importance of new concepts and technologies. The article presents the concept of BEV (Battery Electric Vehicle) and PHEV (Plug-in Hybrid Electric Vehicle) vehicles in relation to modern solutions and their levels of autonomy. The research was conducted in various groups of respondents, while the analyses were carried out mainly with the use of two grouping variables: gender and place of residence. Based on our own research, it can be concluded that due to many different factors, most respondents believe that PHEV hybrid vehicles and electric vehicles (BEV) are currently, and will mo... [more]

The parabolic trough solar collector as a popular technique is widely used in solar concentrating technologies (SCTs). The solar absorber tube is the key position of the trough solar thermal power system. The internal modification of the absorber tube is one of the most interesting techniques for increasing the collector’s performance. At present, most of the methods to enhance heat transfer efficiency focus on designing alternative parabolic trough collectors (PTC) absorbers and improving the internal structure of absorption tubes. Due to the limitation of temperature range, most absorption tubes use oil as heat absorbing liquid, and very few heat absorbing tubes directly use water as working fluid. This is because water is limited by critical heat flux in high temperature environment, resulting in low heat transfer performance. In this work, we designed a new porous absorber tube with the function of allowing liquid resupply and vapor overflow from different paths, which can effectiv... [more]

In grid-connected photovoltaic (PV) systems, a transformer is needed to achieve the galvanic isolation and voltage ratio transformations. Nevertheless, these traditional configurations of transformers increase the weight, size, and cost of the inverter while decreasing the efficiency and power density. The transformerless topologies have become a good solution. However, the problem is that commode-mode voltage and leakage current can occur via the stray capacitors between the PV array and the ground of the inverter. Various transformerless inverters have been introduced with different techniques, such as reducing the common-mode voltage or eliminating the leakage current. Furthermore, to introduce the development of transformerless PV inverters, especially in three-phase two-level inverter systems, this paper provides a comprehensive review of various common-mode voltage reduction three-phase two-level inverters.

The condition of the oil and gas sector is characterized by the complication of geological settings, and there is more competition in energy markets due to the current trend towards decarbonization. These circumstances require oil and gas companies to become more flexible and improve their project economic feasibility studies. The purpose of the research was to develop a methodological approach for the economic evaluation of oil and gas projects that includes choosing and substantiating the choice of engineering solutions that can be used to make decisions on subsequent investing. A comparative analysis of various economic evaluation methods applied to oil and gas projects included the DCF model, DPNV model with modifications, binary discounting, and reverse discounting. Taking into account the specific features of oil and gas projects, the authors provide a rationale for using a risk-free rate to calculate project outflows and a combination of reverse rates to calculate inflows. In ad... [more]

After over a century of internal combustion engines ruling the transport sector, electric vehicles appear to be on the verge of gaining traction due to a slew of advantages, including lower operating costs and lower CO2 emissions. By using the Vehicle-to-Grid (or Grid-to-Vehicle if Electric vehicles (EVs) are utilized as load) approach, EVs can operate as both a load and a source. Primary frequency regulation and congestion management are two essential characteristics of this technology that are added to an industrial microgrid. Industrial Microgrids are made up of different energy sources such as wind farms and PV farms, storage systems, and loads. EVs have gained a lot of interest as a technique for frequency management because of their ability to regulate quickly. Grid reliability depends on this quick reaction. Different contingency, state of charge of the electric vehicles, and a varying number of EVs in an EV fleet are considered in this work, and a proposed control scheme for fr... [more]

Over the last few years, improving power extraction from the wind energy conversion system (WECS) under varying wind speeds has become a complex task. The current study presents the optimum maximum power point tracking (MPPT) control approach integrated with neural network (NN)-based rotor speed control and pitch angle control to extract the maximum power from the WECS. So, this study presents a reference model adaptive control (RMAC) for a direct-drive (DD) permanent magnet vernier generator (PMVG)-based WECS under real wind speed conditions. Initially, the RMAC-based rotor speed tracking control is presented with adaptive terms, which tracks a reference model that guarantees the expected exponential decay of rotor speed error trajectory. Then, to reduce the wind speed measurement errors, a recurrent neural network (RNN)-based training model is presented. Moreover, the asymptotic stability of the proposed control method is mathematically proven by Lyapunov theory. In addition, the pit... [more]

Wind energy is expected to play a significant role in meeting emission targets over the next 20 years. Offshore wind turbines in deep water (>150 m) must be developed due to resource quality, environmental, and activity constraints. Floating offshore wind turbines (FOWT) will be the best technology for reaching these targets. The dynamic submarine electrical cable (DSEC) is a key component of FOWT. Its electric insulation system is intended to withstand a maximum conductor temperature of 90 °C. However, biofouling growth, particularly mussels, can modify the heat transfer around the cable and thus its maximum conductor temperature, as well as temperature fluctuation, affecting the fatigue lifetime. In our work we estimate the effective thermal conductivity of mussels of various ages, as well as the heat transfer coefficient of the water around them. The results revealed that the effective thermal conductivity of juvenile mussels is lower than that of mix (both juvenile and adult) and o... [more]

As environmental pollution deteriorates, the acceleration of decarbonization worldwide is underway. Several countries, including Korea, are incorporating new and renewable energy into existing systems, and various methods of decarbonization are being researched. With changes in the control environment, the expansion of the system linkage of new and renewable energy can cause system instability problems. This paper introduces an operation plan that uses the fast response characteristics of energy storage system(s) (ESS) to improve stability and review system stability as a result of the expansion of new and renewable energy on Jeju Island. Frequency stability was ensured through an analysis of frequency response characteristics in the event of a system accident, and an efficient ESS operation plan was simulated by changing the ESS parameters. Through this simulation, stable ESS operation and hunting in the frequency recovery process were minimized through cooperation between the existin... [more]

This research addressed a need for technical evaluation of the oceanic scenario of Panama for the use of Ocean Thermal Energy Conversion (OTEC). Its bathymetry and location can potentially lead to the exploitation of OTEC, diversifying the energy matrix and helping achieve sustainability. Nevertheless, site selection for OTEC can be a complex task since it involves various alternatives, with different quantitative and qualitative criteria, which may conflict in some cases. Optimization and multiple criteria (MCD) methods have been used lately to address these issues; however, their use is still limited. Here, Analytic Hierarchical Analysis (AHP) is proposed as a MCD method for site selection. Six sites of interest were considered as the alternatives for a plant installment. These sites were chosen, excluding the environmentally and aboriginal protected areas. The quantitative criteria considered were surface and deep-water temperatures, coastline distance, gross and net efficiency. Tho... [more]

The surface properties of coal, interactions with gaseous and vapour media, and knowledge of the pore structure are important in terms of preparation, use, and utilisation of coal. This publication combines new unpublished data with analyses included in earlier publications by the research team to expand and systematise information on the sorption of water vapour, methanol vapour, and the saturated and unsaturated hydrocarbons hexane, 1-hexene, heptane, 1-heptene, octane on coals of different ranks. The study showed that the affinity of coal for water and methanol is related to the content of oxygen in the coal rather than the rank of the coal. Water sorption is a multilayer phenomenon, while methanol sorption is a monolayer phenomenon. The water monolayer is greater than that of methanol for low-rank coal, but for the higher-rank coals it is the opposite. The sorption capacity of the applied hydrocarbons depends on the presence or absence of a double bond and the size of the molecule.... [more]

The working life of a stack is basically determined by the behavior of its weakest monomer; therefore, during a dynamic loading process, high-voltage uniformity plays a key role in stack durability. This work experimentally investigated dynamic responses and voltage uniformity with different loading strategies from an initial state (open-circuit state) to a target current at subzero temperatures. The results presented that the maximum voltage coefficient variation Cv values, representing the relative standard deviation of the monomer voltage, increased from 19.75 to 35.65 and the voltage uniformity sharply decreased with the increase in loading sizes at the stack temperature of −4 °C. It was possible that this could result in the instability of the single cell voltage output and a voltage uniformity fluctuation with a high step loading amplitude. The voltage uniformity became worse as the stack temperature decreased from −2 °C to −8 °C, the voltage uniformity between single cells of th... [more]

This contribution introduces a new hybrid enhanced oil recovery (EOR) method which combines smart water-assisted foam (SWAF) flooding, known as the SWAF process. The concept of applying SWAF flooding in carbonate reservoirs is a novel approach previously unexplored in the literature. The synergy effect of the SWAF technique has the potential to mitigate a number of limitations related to individual (i.e., conventional water injection and foam flooding) methods encountered in carbonates. In general, carbonate rocks are characterized by a mixed-wet to oil-wet wettability state, which contributes to poor oil recovery. Hence, the smart water solution has been designed to produce a dual-improvement effect of altering carbonate rock wettability towards more water-wet, which preconditions the reservoir and augments the stability of the foam lamellae, which has for some conditions more favorable relative permeability behavior. Then the smart water solution is combined with surfactant (surfacta... [more]

Perovskites are a promising class of semiconductor materials, which are being studied intensively for their applications in emerging new flexible optoelectronic devices. In this paper, device manufacturing and characterization of quasi-interdigitated back-contact perovskite solar cells fabricated on flexible substrates are studied. The photovoltaic parameters of the prepared flexible quasi-interdigitated back-contact perovskite solar cells (FQIBC PSCs) are obtained for the front- and rear-side illumination options. The dependences of the device’s open-circuit potential and short-circuit current on the illumination intensity are investigated to determine the main recombination pathways in the devices. Spectral response analysis of the devices demonstrates that the optical transmission losses can be minimized when FQIBC PSCs are illuminated from the front-side. Optoelectronic simulations are used to rationalize the experimental results. It is determined that the obtained FQIBC PSCs have... [more]

The purpose of the following article is to present the situation of the energy market from a household perspective between 2010 and 2020 in selected EU countries (the group of member states which joined EU after 2004). The selected countries when joining the EU had similar economic indicators and to some extent were similar in other macro-economic situations (personal income, unemployment rate, GDP level and annual growth). This article analyzes the past and current situation of the household ability expenditure on electricity and energy resources (petrol—eurosuper 95 and diesel and natural gas), taking into account price, tax conditions and the real possibility to purchase the analyzed energy sources (based on annual net salaries). The paper includes the conclusions and prospects for the future. The main objective of the study is to determine the ability amount of expenditure on electricity, natural gas and liquid fuels by household in the countries that joined the European Union afte... [more]

Temporally and spatially resolved laser-induced breakdown spectroscopy (LIBS) was applied to a four-stroke, single-cylinder test engine’s cyclic exhaust gas to demonstrate engine performance. The LIBS technique provided quantitative air-to-fuel ratio (A/F) measurements by generating localized breakdown plasma during the compression and exhaust strokes. The results showed that the timing and duration settings of the emission energy ionization and molecular spectra affect the intensity peaks. Optimum measurements performed between 200 ns and 10 ms after breakdown resulted in observed atomic spectra of CI (248 nm), Hβ (485 nm), Hα (656 nm), NI (745, 824 nm), and OI (777, 844 nm). The intensities of CI (248 nm) and Hα (656 nm) decreased with increasing A/F, whereas the intensity ratios of NI and OI remained constant. A decrease in the intensity ratio of C/O and Hα/O was observed as the A/F increased. This study is a major step toward defining a means of using LIBS to control the A/F ratio... [more]

The United Nations Framework Convention on Climate Change Paris Agreement has been announced as a crucial step towards combating the global threat of climate change. In the light of ambitious plans for further renewable energy sources development, high demand for nonenergy materials critical for RES is greatly expected. In conclusion, future energy security will be surely based on nonenergy commodities critical for them. As this article directly relates to issues related to new technologies and energy security in new form, the main purpose of this study is to examine the impact of energy commodity prices, namely crude oil, natural gas and coal prices on selected metal prices such as aluminium, chromium, cobalt, copper, lead, nickel, silver, tin, or zinc, both before and over the Paris Agreement period. We are looking for new insights in terms of relationships between traditional fossil fuels and metals used in clean energy technologies potentially established or strengthened shortly af... [more]