Gasification is a promising thermochemical technology used to convert waste materials into energy with the introduction of low amounts of an oxidant agent, therefore producing an environmental impact that is lower when compared to incineration and landfilling. Moreover, gasification allows a sustainable management of wastes and reduces the use of fossil fuels responsible for the increment of greenhouse gases. This work aimed to perform gasification tests with solid recovered fuels (SRF) containing organic fractions mainly retrieved from construction and demolition wastes to assess the potential for energy conversion. Tests were conducted in a pilot-scale downdraft gasifier (maximum feedstock input of 22 kg/h) at c.a. 800 °C, using SRF samples containing different proportions of polymeric wastes ranging between 0 and 20 wt %. Gas and chars obtained as by-products were analysed to evaluate their properties and to establish valid pathways for their valorisation. The addition of polymeric... [more]

The largest Precambrian gasfield in China has been found in the central Sichuan Basin. It has been assumed as an Ediacaran (Sinian) mound−shoal, microfacies-controlled, dolomite reservoir. However, the extremely low porosity−permeability and heterogeneous reservoir cannot establish high production by conventional development technology in the deep subsurface. For this contribution, we carried out development tests on the fractured reservoir by seismic reservoir description and horizontal well drilling. New advances have been made in recent years: (1) the prestack time and depth migration processing provides better seismic data for strike-slip fault identification; (2) seismic planar strike-slip structures (e.g., en échelon/oblique faults) and lithofacies offset together with sectional vertical fault reflection and flower structure are favorable for strike−slip fault identification; (3) in addition to coherence, maximum likelihood and steerable pyramid attributes can be used to identify... [more]

The swift and successful transition towards a fossil fuel-free economy is amongst the most complex challenges ever faced by humanity, implicating intricate connections and trade-offs with the so-called water−energy−food nexus [...]

Vertical Axis Wind Turbines (VAWTs) are omni-directional, low-cost, low-efficiency wind power extractors. A conventional drag-based VAWT consists of multiple thin rotor blades with a typical peak Tip Speed Ratio (λ) of < 1. Their lower cut-in speed and maintenance cost make them ideal for power generation in urban environments. Numerous studies have been carried out analysing steady operation of VAWTs and quantifying their performance characteristics, however, minimal attention has been paid to their start-up dynamics. There are a few recent studies in which start-up dynamics of lift-based VAWTs have been analysed but such studies for drag-based VAWTs are severely limited. In this study, start-up dynamics of a conventional multi-blade drag-based VAWT have been numerically investigated using a time-dependant Computational Fluid Dynamics (CFD) solver. In order to enhance the start-up characteristics of the drag-based VAWT, a stator has been integrated in the design assembly. The numer... [more]

This study presents a simple indoor air quality diagnosis program for school office spaces, which are occupied for long durations by teachers, and indoor sports facilities, whose utilization has been on the rise in response to high concentrations of pollutants in outdoor air. The proposed program was made with Visual Basic for Applications (VBA) and Microsoft Excel. This program requires inputs which can be easily determined or measured even by nonexperts and can check the current status of indoor air quality such as CO2 and PM2.5 concentrations and predict the effect if changes are made. In addition, it is possible to diagnose indoor air quality before and after class and compare it with the initial plan so that if it exceeds the indoor air quality maintenance standard range, it can be improved by using a ventilation system and an air purifier. The development of the program was divided into four stages. First, prior research on the influencing factors was investigated. Second, influe... [more]

Hydrogen (H2) is an attractive energy carrier to move, store, and deliver energy in a form that can be easily used. Field proven technology for underground hydrogen storage (UHS) is essential for a successful hydrogen economy. Options for this are manmade caverns, salt domes/caverns, saline aquifers, and depleted oil/gas fields, where large quantities of gaseous hydrogen have been stored in caverns for many years. The key requirements intrinsic of a porous rock formation for seasonal storage of hydrogen are: adequate capacity, ability to contain H2, capability to inject/extract high volumes of H2, and a reliable caprock to prevent leakage. We have carefully evaluated a commercial non-isothermal compositional gas reservoir simulator and its suitability for hydrogen storage and withdrawal from saline aquifers and depleted oil/gas reservoirs. We have successfully calibrated the gas equation of state model against published laboratory H2 density and viscosity data as a function of pressure... [more]

The uniform and smaller-sized (~3 μm) LiNi0.8Co0.1Mn0.1O2 (SNCM) particles are prepared via a fast nucleation process of oxalate co-precipitation, followed by a two-step calcination procedure. It is found that the fast nucleation by vigorous agitation enables us to produce oxalate nuclei having a uniform size which then grow into micron-particles in less than a few minutes. The impacts of solution pH, precipitation time, calcination temperature, and surface modification with ZrO2 on the structural, morphological, and electrochemical properties of SNCM are systematically examined to identify the optimal synthetic conditions. A novel bimodal cathode design has been highlighted by using the combination of the SNCM particles and the conventional large (~10 μm) LiNi0.83Co0.12Mn0.05O2 (LNCM) particles to achieve the high volumetric energy density of cathode. The volumetric discharge capacity is found to be 526.6 mAh/cm3 for the bimodal cathode L80% + S20%, whereas the volumetric discharge ca... [more]

In current power station boilers, fuel burns at a low temperature, which results in low exergy efficiency. This research combined the second law of t with the boiler structure to maximize the efficiency of a 350 MW power plant boiler. A three-dimensional simulation of the combustion process at the power plant boiler is performed. A one-dimensional simulation model of the boiler is then constructed to calculate the combustion exergy loss, heat transfer exergy loss, and boiler exergy efficiency. Under the principle of high-temperature air combustion technologies, this paper also proposes a new structure and improved operating parameters to improve the exergy efficiency of boilers by reducing the heat exchange area of the economizer and increasing the heat exchange area of the air preheater. Simulation results show that the exergy efficiency of the boiler increased from 47.29% to 48.35% through the modified model. The simulation outcomes can instruct future optimal boiler design and contr... [more]

The main sources of environmental pollution with heavy (ecotoxic) metals include industry, including utility and municipal power engineering, but also waste incineration plants. Fuel shortages and their constantly growing prices raise concerns that energy will be commonly obtained from waste outside of installations intended for this purpose (i.e., outside waste incineration plants). The greatest concern stems from the risk of burning waste in low-power boilers—domestic boilers. Waste incineration plants and utility power plants are equipped with flue gas cleaning installations (FGD), but low-power boilers are not. The exhaust gases are directly introduced into the atmosphere, which results in the introduction into the air of, inter alia, toxic heavy metals. Therefore, it is necessary to conduct activities aimed at retaining ecotoxic metals in the solid−slag residue. The paper presents the results of laboratory tests of the emission capacity of Cd, Cu, Zn bound in various chemical form... [more]

In the context of international carbon neutrality, energy prices are affected by several nonlinear and nonstationary factors, making it challenging for traditional forecasting models to predict energy prices effectively. The existing literature mainly uses linear models or a combination of multiple models to forecast energy prices. For the nonlinear relationship between variables and the mining of historical data information, the prediction strategy and accuracy of the existing literature need to be improved. Thus, this paper improves the prediction accuracy of energy prices by developing a “decomposition-reconstruction-integration” thinking strategy that affords medium- and short-term energy price prediction based on carbon constraint, eigenvalue transformation and deep learning neural networks. Considering 2011−2020 as the research period, the prices for traditional energy resources and polysilicon in clean photovoltaic energy raw materials are selected as representatives. Based on e... [more]

Induction motors have gained a renewed interest due to this new shift from conventional power sources to electric power. These motors are known for their high commencing torque, adequate speed control and reasonable overload capacity. However, induction motors have an innate thermal issue wherein their lifespan and performance are strongly temperature dependent. Hence, it is highly essential to focus on the thermal management aspect of these motors to ensure reliability and enhance performance. Thus, the major purpose of the paper is to comprehensively review various approaches and methods for thermal analysis, including finite element analysis, lumped parameter thermal network and computational fluid dynamics tools. Moreover, it also presents various cooling strategies commonly adopted in induction motors. Furthermore, this study also suggests an integrated approach with two or more cooling strategies to be the need of the hour. These will combine the benefits of the individual system... [more]

In this study, a new method for biomass thermal treatment was introduced. The volatile organic compounds (VOCs) of Ficus hispida biomass were obtained via hydrodistillation. The qualitative analysis of VOCs performed by GC−MS and GC−FID techniques identified pentadecanal (14.65%), 2-(E)-hexenal (11.15%), and 2-butyl-5-methyl-2-hexenoic acid ethyl ester (8.53%) as the major compounds. The chemical components varied significantly from the previous study. The results of the DPPH, ABTS, and FRAP methods gave IC50 and antioxidant capacity values of 3.08 ± 0.024 mg/mL, 0.44 ± 0.009 mg/mL, and 135.64 ± 25.49 mM/g, respectively. From the results, the VOCs distilled from F. hispida leaves have an antioxidant property that can be utilized as a natural botanical supplement as an antioxidant and preservative. In addition, the present research offers additional scientific support and a chemical basis for future natural drug discovery.

This paper defines an agile power system as a system in which the physical structure can change due to the connection/disconnection of subsystems, such as microgrids. These systems pose serious difficulties in their operations and control. Some of these challenges are reviewed. One operational issue is the energy balancing or the load frequency control problem when microgrids with a low inertia are connected to the main grid. The paper identifies the need for new rules of operation. Furthermore, in this paper, decentralized and data-driven voltage control designs are proposed, compared and illustrated on a microgrid. They take into consideration the structure and the usage of the large amount of data provided by the proliferation of sensors.

Successful energy transitions, also referred to as leapfrog development, present enormous prospects for EU nations to become carbon neutral by shifting from fossil fuels to renewable energy sources. Along with climate change, EU countries must address energy security and dependency issues, exacerbated by factors such as the COVID-19 pandemic, rising energy costs, conflicts between Russia and Ukraine, and political instability. Diversifying energy sources, generating renewable energy, increasing energy efficiency, preventing energy waste, and educating the public about environmental issues are proposed as several strategies. The study draws the conclusion that central European countries may transition to a clean energy economy and become carbon neutral on economic and strategic levels by locating alternative clean energy supply sources, reducing energy use, and producing renewable energy. According to the study, the EU energy industry can be decarbonised and attain energy security using... [more]

The ammonia oxidation reaction on solid platinum−rhodium gauze is a critical step in nitric acid production. As the global demand for food and fertilisers keeps steadily growing, this remains an essential reaction in the chemical industry. However, harsh conditions inside ammonia burners lead to the degradation of catalytic meshes, severely hindering this process. This manuscript is focused on two issues. The first is the influence of catalyst gauze geometry and process parameters on the efficiency of ammonia oxidation on platinum−rhodium gauze. The second investigated problem is the influence of geometry on catalyst fibre degradation and the movement and deposition of entrained platinum particles. Computational Fluid Dynamics was utilised in this work for calculations. Different catalyst gauze geometries were chosen to examine the relationship between wire geometry and heat and mass transfer by analysing temperature and flow fields. Significantly, the analysis of the temperature gradi... [more]

Forecasting return and profit is a primary challenge for financial practitioners and an even more critical issue when it comes to forecasting energy market returns. This research attempts to propose an effective method to predict the Brent Crude Oil return, which results in remarkable performance compared with the well-known models in the return prediction. The proposed hybrid model is based on long short-term memory (LSTM) and convolutional neural network (CNN) networks where the autoregressive integrated moving average (ARIMA) and generalized autoregressive conditional heteroscedasticity (GARCH) outputs are used as features, along with return lags, price, and macroeconomic variables to train the models, resulting in significant improvement in the model’s performance. According to the obtained results, our proposed model performs better than other models, including artificial neural network (ANN), principal component analysis (PCA)-ANN, LSTM, and CNN. We show the efficiency of our pro... [more]

This paper presents a detailed review of the streaming electrification phenomena of different insulating fluids for power transformers. The comparison of different techniques used to assess the charging tendency of fluids is discussed depending on the flow type (planar or centrifugal), volume of oil, and interface material. The charge separation between the insulating fluid and metallic/pressboard interfaces is explained in terms of the electrical double layer formation involving a fixed layer and diffuse layer. Based on the experimental results, the streaming electrification is observed to be a function of various factors such as speed, temperature, electric field, and surface roughness. Depending on the molecular structure of insulating liquids that come into contact with solid insulation at the interface, the streaming current can increase; hence, a suitable additive (benzotriazole, fullerene, Irgamet 39) is selected based on the type of fluid and charge polarity. The degradation of... [more]

This article presents measurements of the emission of salt dust discharged into the atmosphere in the Wieliczka Salt Mine. Industrial tests have been carried out cyclically since 2004. The research methodology included six measurements of the salt dust’s mass increments on the filters, including three before the inlet to the desalination installation and three measurements at the emitter outlet. In order to limit errors resulting from the diversity of concentrations in the mixture of dosed brine, three series of measurements are carried out each time. The proposed research methodology uses the Aspirator Stationary (AS-50) gravimetric aspirator for measurements with a designed probe adjusted to the characteristics of the dedusting installation used. The conducted tests allowed calculation of the efficiency of the scrubber and confirm the usefulness of the measuring probe used. Moreover, long-term and cyclical measurements make it possible to observe the effectiveness of the installation... [more]

The thermal performance of fin-and-tube heat exchangers (HX) is a crucial aspect in a multitude of applications and fields; several design and operational parameters influence this performance. This study focuses on the issue of flow maldistribution and its effect on the HX thermal performance. For this purpose, an experimental setup is designed and implemented to emulate the conditions under which an automotive heat exchanger operates in regard to the non-uniform upstream airflow velocity distribution over the HX surface. The setup allows obtaining various configurations of airflow velocity non-uniformity of some desired mean velocity and standard deviation. The experimental results reveal that a higher degree of non-uniformity (higher standard deviation of the velocity distribution) causes an increased deterioration of the HX thermal performance. For example, at a water flowrate of 200 L/h and a mean airflow velocity of 2 m/s, increasing the standard deviation from 0 to 2 m/s (i.e.,... [more]

A compact, rapid, and portable off-chip pneumatic control valve is significant for the miniaturization and integration of external pneumatic systems for microfluidic chips. In this work, an off-chip microvalve with a high-speed electromagnetic switch actuator and a polydimethylsiloxane (PDMS) material valve body has been designed to be easily encapsulated, simulated using MATLAB/Simulink software, and tested in a micromixer. Multi-physical coupling mathematical models are developed based on the elastic deformation force of the valve membrane, the driving force of the valve core, and the fluid force in the microchannel. Two single microvalves are used to form a three-way microvalve, which can control the air pressure in a pneumatic microchannel on the microfluidic chip. The relationship between the flow−duty cycle, the flow−pressure difference of the single electromagnetic microvalve, and the load pressure of the three-way microvalve is simulated and analyzed. Sample mixing performance... [more]

This study is a systematic analysis of selected research articles about power-to-X (P2X)-related processes. The relevance of this resides in the fact that most of the world’s energy is produced using fossil fuels, which has led to a huge amount of greenhouse gas emissions that are the source of global warming. One of the most supported actions against such a phenomenon is to employ renewable energy resources, some of which are intermittent, such as solar and wind. This brings the need for large-scale, longer-period energy storage solutions. In this sense, the P2X process chain could play this role: renewable energy can be converted into storable hydrogen, chemicals, and fuels via electrolysis and subsequent synthesis with CO2. The main contribution of this study is to provide a systematic articulation of advanced data-driven methods and latest technologies such as the Internet of Things (IoT), big data analytics, and machine learning for the efficient operation of P2X-related processes... [more]

This study aims to investigate, from a technical and an environmental perspective, various alternatives for acetic acid concentration for maximizing acetic acid production, its purity, and in the meantime, minimizing the energy usage and the environmental impact. Liquid−liquid extraction followed by azeotropic distillation using different solvents such as: (i) ethyl acetate, (ii) isopropyl acetate, and (iii) a mixture containing isopropyl acetate and isopropanol were first explored, using process flow modeling software. The three cases were compared considering various technical key performance indicators (i.e., acetic acid flow-rate, acetic acid purity, acetic acid recovery, power consumption, thermal energy used, and number of equipment units involved) leading to the conclusion that the usage of the isopropyl acetate—isopropanol mixture leads to better technical results. The isopropanol-isopropyl acetate mixture was furthermore investigated in other two cases where process intensific... [more]

In recent years, the rapid consumption of fossil fuels has brought about the energy crisis and excess CO2 emission, causing a series of environmental problems. Photocatalytic CO2 reduction technology can realize CO2 emission reduction and fuel regeneration, which alleviates the energy crisis and environmental problems. As the most widely used LDH material in commercial application, MgAl-layered double hydroxide (MgAl-LDH) already dominates large-scale production lines and has the potential to be popularized in CO2 photoreduction. The adjustable component, excellent CO2 adsorption performance, and unique layer structure of MgAl-LDH bring specific advantages in CO2 photoreduction. This review briefly introduces the theory and reaction process of CO2 photocatalytic reduction, and summarizes the features and drawbacks of MgAl-LDH. The modification strategies to overcome the drawbacks and improve photocatalytic activity for MgAl-LDH are elaborated in detail and the development perspectives... [more]

The continuous technical improvements involving electric motors, battery packs, and general powertrain equipment make it strictly necessary to predict or evaluate the energy consumption of electric vehicles (EVs) with reasonable accuracy. The significant improvements in computing power in the last decades have allowed the implementation of various simulation scenarios and the development of strategies for vehicle modelling, thus estimating energy consumption with higher accuracy. This paper gives a general overview of the strategies adopted to model EVs for evaluating or predicting energy consumption. The need to develop such solutions is due to the basis of each analysis, as well as the type of results that must be produced and delivered. This last point strongly influences the whole set-up process of the analysis, from the available and collected dataset to the choice of the algorithm itself.

Global warming and climate change, accompanied and assisted by rapid economic and population growth, are causing a sharp rise in cooling demands and stressing the already-limited supply of freshwater for many countries worldwide, especially those developing under hot-climate conditions. Thus, it is imperative to find solutions to meet cooling and freshwater needs without negatively affecting the environment and exacerbating the global warming problem. Solar-driven hybrid desalination/cooling technologies are a promising solution that can help in reducing greenhouse gas emissions and increasing overall efficiency and energy savings. The present study summarizes research efforts in meeting cooling and freshwater demands using the available solar resources. Various solar desalination technologies, such as multi-effect distillation (MED), single and multi-stage flash (MSF), reverse osmosis (RO), adsorption, absorption desalination, and membrane distillation (MD), and their integration with... [more]