CO2 net neutralization by 2050 is a global target. Renewable energy and nuclear power generation are emerging as major power sources for CO2 net neutralization. Therefore, this paper comprehensively reviews the load-following operation method of nuclear power plants as a method to compensate for intermittency, which is the biggest weakness of renewable energy. First, this paper looks at the types of SMRs and elaborates the concept and necessity of load following. The comprehensive requirements for the load-following operation of an SMR, i.e., planned operation, automatic generation control, governor-free operation, cooperative control of the reactor and turbine generator, unit control of a multiple-module SMR, cogeneration, etc., are studied. Finally, the interaction between an SMR and the power grid during load-following operation and other technical issues are also reviewed. This paper can be used as a guide for load-following operations or as a guide for requirement analysis when de... [more]

The availability of freshwater and energy is a serious issue in remote and islanded areas, especially at a small scale, where there may not be the possibility to access the grid and/or water distribution systems. In this context, polygeneration systems operating on the basis of local, renewable energy sources can be an answer to the users’ demand for electricity, heating, cooling, and domestic hot water. The scope of the proposed paper was to investigate, numerically, the energy and economic feasibility of a novel hybrid polygeneration system powered by biomass, solar, and wind energy for a micro-district of households. The proposed system consists of a biomass-fueled steam cycle, wind turbine, photovoltaic field coupled with thermal and electrical energy storage, adsorption chiller, and a reverse osmosis water desalination unit. The system is also assisted by an LPG generator set running as backup. The system provides space heating and cooling, electrical energy, and fresh and domesti... [more]

A two-phase hydraulic turbine’s performance and flow field were predicted under different Inlet Gas Volume Fractions (IGVF) with incompressible and compressible models, respectively. The calculation equation of equivalent head, hydraulic efficiency, and flow loss considering the expanding work of compressible gas were deduced based on the energy conservation equations. Then, the incompressible and compressible results, including the output power and flow fields, are compared and analyzed. The compressible gas model’s equivalent head, output power, and flow loss are higher than the incompressible model, but the hydraulic efficiency is lower. As the IGVF increases, the gas gradually diffuses from the blade’s working surface to its suction surface. The gas−liquid separation happens at the runner outlet in the compressible results due to the gas expansion. The area of the low-pressure zone in the incompressible results increases with the IGVF. However, it decreases with the IGVF in the com... [more]

Shale gas reservoirs are unconventional resources with great potential to help meet energy demands. Horizontal drilling and hydraulic fracturing have been extensively used for the exploitation of these unconventional resources. According to engineering practice, some shale gas wells with low flowback rate of fracturing fluids may obtain high yield which is different from the case of conventional sandstone reservoirs, and fracturing fluid absorbed into formation by spontaneous imbibition is an important mechanism of gas production. This paper integrates NMR into imbibition experiment to examine the effects of fractures, fluid salinity, and surfactant concentration on imbibition recovery and performance of shale core samples with different pore-throat sizes acquired from the Longmaxi Formation in Luzhou area, the Sichuan Basin. The research shows that the right peak of T2 spectrum increases rapidly during the process of shale imbibition, the left peak increases rapidly at the initial sta... [more]

Multi-level inverters (MLIs) have been widely used in recent years due to their various advantages in industrial and grid-connected applications. Traditional MLI topologies are being hampered by the rapid surge of renewable energy systems (RES) as a result of performance difficulties such as poor power reliability, an economically unviable structure, and a lack of efficiency. These difficulties are due to the traditional MLI topologies’ inability to keep up with the increasing demand for RES. Because of concerns about performance and limitations posed by classic MLI topologies, researchers have found themselves driven to the idea of building innovative hybrid MLI topologies. This study provides a comprehensive analysis of multilevel inverter systems that are wired into the main power supply. Grid-connected inverter types and their configurations are discussed in depth in this review. Diverse multi-level inverter topologies, as well as the different approaches, are divided into various... [more]

Worldwide mopeds and motorcycles are taking on a growing main role in private mobility with a direct impact on air pollution, particularly in urban contexts of many Asian and European countries. In a preceding experimental investigation, HC and CO emissions were measured in the exhaust of a last-generation motorcycle belonging to the Euro-3 legislative category. Since exhaust emissions and fuel consumption are very sensitive to variations in vehicles instantaneous speed and acceleration, in this research new experimental results are used to recognize the kinematic parameters that cause higher engine-out emissions. In this paper, the hybrid electric propulsion is proposed for motorcycle application to reduce exhaust emissions in particular driving conditions which include high levels of acceleration with resultant rapid steep increase in engine speed. In such operating conditions, an enrichment of the air/fuel mixture is required, which affects the catalyst conversion efficiency. Subseq... [more]

The rotating vortex rope, which can be decomposed in the rotating and the plunging modes, is the origin of pressure fluctuations in the draft tube cone when hydraulic turbines operate at part load, compromising the structural integrity and limiting the output load. A measurement campaign was carried out in a Kaplan turbine model which is a replica of the experimental 10 MW Porjus U9 prototype machine along a propeller curve to study the rotating vortex rope’s excitation levels and the induced structural responses. A complete set of sensors mounted on-board and off-board was used to measure pressures, forces, torques, accelerations, displacements, and strains. The characteristic frequencies and amplitudes of the pressure fluctuations and of the corresponding induced loads and vibrations associated with the two modes were quantified in a wide range of operating conditions at part load. The two modes are detected at different frequencies depending on the sensor position. Moreover, their f... [more]

Gas control in the heading face of a coal roadway is an important and difficult point in coal mining in China. On the basis of analyzing the disadvantages of high gas control cost and long drainage period in the existing mine heading face, a long-distance pre-drainage method of long-distance drilling is proposed to control the gas in the heading face so as to improve the tunneling speed. Applied to the engineering geological conditions of Changcun coal mine, the technology is studied in detail. First, a gas migration model considering permeability changing with time is established, and the model is put into the numerical simulation software to study the variation law of permeability and gas pressure under the conditions of single borehole and multi-borehole drainage. The results show that with the increase of drainage time, the permeability around the borehole increases gradually, the gas pressure decreases gradually, and the permeability at the borehole boundary increases the most, re... [more]

This study proposes a fuel supply system for dual-fuel propulsion engines using liquefied natural gas (LNG) and ammonia to control carbon emissions. The independent fuel supply system of LNG and ammonia is configured as a hybrid system. The operating pressure of the re-condenser is determined as a process variable according to the power consumption and flow rate of the non-condensable boil-off gas. The independent and hybrid systems are compared and evaluated through thermodynamic analyses, including specific power consumption (SPC) and exergy analyses, with respect to the fuel ratio and engine load. When the engine load is 100% in Case 1 for a 40% carbon reduction by 2030, the hybrid system exhibits an SPC reduction of 70% and exergy efficiency increase of 16% compared with the independent system.

Inorganic nanopores occurring in the shale matrix have strong hydrophilicity and irreducible water (IW) film can be formed on the inner surface of the pores making gas flow mechanisms in the pores more complex. In this paper, the existence of irreducible water (IW) in inorganic pores is considered, and, based on the Knudsen number (Kn) correction in shale pores, a shale gas apparent permeability model of inorganic nano-pores is established. The effect of the Kn correction on the apparent permeability, the ratio of flow with pore radius and the effect of IW on the apparent permeability are assessed. The main conclusions are as follows: (1) at low pressure (less than 10 MPa) and for medium pore size (pore radius range of 10 nm−60 nm), the effect of the Kn correction should be considered; (2) considering the effect of the Kn correction, bulk phase transport replaces surface diffusion more slowly; considering the existence of IW, bulk phase transport replaces surface diffusion more slowly;... [more]

Renewable energy sources such as wind turbines and photovoltaics are the key to an environmentally friendly energy supply. However, their volatile power output is challenging in regard to supply security. Therefore, flexible energy systems with storage capabilities are crucial for the expansion of renewable energy sources since they allow storing off-demand produced power and reconverting and supplying it on-demand. For this purpose, a novel power plant concept is presented where high-temperature energy storage (HTES) is integrated between the recuperator and the combustor of a conventional micro gas turbine (MGT). It is used to store renewable energy in times of oversupply, which is later used to reduce fuel demand during MGT operation. Hereby, pollutant emissions are reduced significantly, while the power grid is stabilized. This paper presents a numerical process simulation study, aiming to examine the influence of different storage temperatures and load profiles of HTES on the MGT... [more]

The article is focused on the issue of blackouts in a water industry and the selection of a renewable energy source for a water treatment plant. In the case of power outage, it is necessary to constantly ensure the supply of a drinking water, if this requirement would not be met, it could cause of deterioration of hygiene and health of the population. To be able to convey drinking water during a blackout, it is mandatory to have a backup power supply. The state of the current water treatment plants in the Czech Republic is that they are using diesel generators as backup power supply, which causes air pollution. There are other options of power supply that can be used, such as renewable energy sources. By using a multi-criteria analysis method, renewable energy sources were analyzed for a water treatment plant in the selected region. Based on the results, it seems that the most suitable choice is a small hydro power plant at the entry points of water treatment plant. Other possibilities... [more]

The geochemical statistics indicate that the wetness (C2~C5/C1~C5) of over-mature shale gas with carbon isotope reversal is less than 1.8%. The magnitude of carbon isotope reversal (δ13C1−δ13C2) increases with decreasing wetness within a wetness range of 0.9~1.8% and then decreases at wetness <0.9%. The experimental result demonstrates that CH4 polymerization proceeding to CH4 substantial cracking is an important factor involved in isotope reversal of over-mature shale gas. Moreover, δ13C1−δ13C2 decreases with an increase in experimental temperature prior to CH4 substantial cracking. The values of δ13C1 and δ13C2 tend to equalize during CH4 substantial cracking. The δ13C1−δ13C2 of mud gas investigated at different depths during shale gas drilling in the Sichuan Basin increases initially, then decreases with further increase in the depth, and finally tends to zero, with only a trace hydrocarbon gas being detectable. Thus, the approximately equal value between δ13C1 and δ13C2 for over... [more]

The article concerns the energy security of a wastewater treatment process caused by unforeseen situations related to the risk of electrical power outages. In this case, renewable energy sources based on distributed generation power systems can solve this problem in each wastewater treatment plant. The article highlights e related challenges and proposes the direction of solutions in this regard based on Czech conditions. The first part of the paper deals with the consequences of long-term outage of wastewater treatment plants on the population and the environment. There are several solutions presented for blackout conditions, and model calculations are made based on data from a Czech wastewater treatment plant. Diesel engine-generators, biogas as a cogeneration source of heat and electricity, solar panels with storage systems and combined biogas and solar systems were considered as approaches to provide energy autonomy during a blackout in a wastewater treatment plant. Special attenti... [more]

Over many decades, isolated regions (e.g., islands, rural and remote areas) have heavily relied on diesel engine for producing power and energy. However, due to depleting fossil fuels and concerning emissions, biodiesels could be the substitute for diesel in power generation sectors. This study developed a single-zone thermodynamic model to predict the engine performances such as brake power (BP), torque, brake thermal efficiency (BTE), brake-specific fuel consumption (BSFC) and ignition delay (ID) times for diesel and jojoba biodiesel. The experiments were conducted on a fully automated, 4-cylinder, 4-stroke, liquid-cooled direct injection 3.7-L diesel engine fueled with diesel (D100) and three jojoba blends (JB5, JB10, and JB20) to validate the model. The performance simulation results agreed with experimental data for all tested fuels at 1200 to 2400 rpm speed and 25%, 50%, 75%, and 100% loading operation. The minimum error (3.7%) was observed for BP for D100 at 2000 rpm and 100% lo... [more]

The unconvertible portion of incident radiation on solar panels causes an increase in their temperature and a decrease in efficiency due to the negative temperature coefficient of the maximum power. This problem is dealt with through the use of cooling systems to lower the temperature of photovoltaic (PV) panels. However, the developments are focused on the loss of efficiency or extract the heat out of the solar panel, rather than optimizing the solution to produce a net gain in the electric power output. Therefore, this study proposes the analytical model for the cell temperature, irradiance and design of absorbers. Furthermore, the cooling systems for the hybrid solar panels were developed through analytical modeling of the solar cell temperature behavior and heat exchange between the fluid and back surface of the PV module in MATLAB. The design parameters such as mass flow rate, input power, solar cell temperature, velocity, height, number of passes and maximum power output were opt... [more]

As non-renewable energy sources are in the verge of exhaustion, the entire world turns towards renewable sources to fill its energy demand. In the near future, solar energy will be a major contributor of renewable energy, but the integration of unreliable solar energy sources directly into the grid makes the existing system complex. To reduce the complexity, a microgrid system is a better solution. Solar energy forecasting models improve the reliability of the solar plant in microgrid operations. Uncertainty in solar energy prediction is the challenge in generating reliable energy. Employing, understanding, training, and evaluating several forecasting models with available meteorological data will ensure the selection of an appropriate forecast model for any particular location. New strategies and approaches emerge day by day to increase the model accuracy, with an ultimate objective of minimizing uncertainty in forecasting. Conventional methods include a lot of differential mathematic... [more]

Freshwater scarcity is a significant concern due to climate change in some regions of Brazil; likewise, evaporation rates have increased over the years. Floating photovoltaic systems can reduce water evaporation from reservoirs by suppressing the evaporating area on the water surface. This work evaluated the effects of floating photovoltaic systems on water evaporation rates in the Passaúna Reservoir, southeastern Brazil. Meteorological data such as temperature, humidity, wind speed, and solar radiation were used to estimate the rate of water evaporation using FAO Penman−Monteith, Linacre, Hargreaves−Samani, Rohwer, and Valiantzas methods. The methods were tested with the Kruskal−Wallis test, including measured evaporation from the nearest meteorological station to determine whether there were significant differences between the medians of the methods considering a 95% confidence level for hypothesis testing. All methods differed from the standard method recommended by the FAO Penman−M... [more]

In response to severe environmental and energy crises, the world is increasingly focusing on electric vehicles (EVs) and related emerging technologies. Emerging technologies for EVs have great potential to accelerate the development of smart and sustainable transportation and help build future smart cities. This paper reviews new trends and emerging EV technologies, including wireless charging, smart power distribution, vehicle-to-home (V2H) and vehicle-to-grid (V2G) systems, connected vehicles, and autonomous driving. The opportunities, challenges, and prospects for emerging EV technologies are systematically discussed. The successful commercialization development cases of emerging EV technologies worldwide are provided. This review serves as a reference and guide for future technological development and commercialization of EVs and offers perspectives and recommendations on future smart transportation.

In the scientific discourse on consumption, increasingly more attention is being paid to sustainable development. Regarding the fact that not only various types of enterprises, but also consumers contribute to the excessive consumption of natural resources, it is of crucial importance to reduce the knowledge gap in the field of sustainable consumer behavior and decision-making processes related to the choice of organic products. The paper aims to present the decision-making processes of Polish consumers of renewable energy against the background of other categories of ecological products. Special attention is paid to the extent in which the offer is adjusted to the needs of consumers of renewable energy in Poland, compared to other categories of ecological products. The paper also shows the perception of the consumer of ecological products by buyers of renewable energy and by people who do not buy ecological products. The paper is based on a literature review and the results of a quant... [more]

This article is an attempt to explore the heat transfer features of the steady three-dimensional rotating flow of magneto-hydrodynamic hybrid nanofluids under the effect of nonlinear radiation over the bi-directional stretching surface. For this purpose, two different nano-particles, namely silver (Ag) and molybdenum di-sulfide (MoS2), were selected. Three different conventional base fluids were utilized to form desired hybrid nanofluids such as water (H2O), engine oil (EO), and ethylene glycol (EG). We obtained steady three-dimensional highly nonlinear partial differential equations. These highly nonlinear partial differential equations cannot be solved analytically, so these equations were handled in MATLAB with the BVP-4C technique with convergence tolerance at 10−6. The graph depicts the effect of the magnetization effect, thermal radiation, and stretching ratio on rotating hybrid nanofluids. Additionally, the impact of thermal radiation on the heat coefficient of three different h... [more]

The design of a gas diffusion layer (GDL) is an effective way to manage water transport, thus improving the performance of air-cooled fuel cells. In the present study, three group designs of GDL with polytetrafluoroethylene (PTFE)—uniformly doped, in-planed sandwich doped and through-plane gradient doped—are proposed, and their effects on the performance of air-cooled fuel cells are explored by numerical simulation. The distribution of key physical quantities in the cathode catalyst layer (CCL), current density and the uniformity of current density distribution in the CCL were analyzed in detail. The results show that properly reducing the amount of PTFE in GDL is beneficial to promoting the water retaining capacity of air-cooled fuel cells, and then improving the performance of fuel cells. The performance of the in-plane sandwich GDL design cannot exceed the design with 10% PTFE uniformly doped, and this design will aggravate the uneven distribution of current density in CCL. Compared... [more]

Straw is a by-product from cereal cultivation. Using straw surplus as a biofuel is a popular means of its management. However, before being used for fuel purposes, straw can be successfully used as a sorbent. The present study investigated the sorption properties of wheat straw (Triticum aestivum L.) modified with ammonia water and epichlorohydrin against the reactive dye Reactive Black 5 (RB5). The tested sorbents were characterized based on FTIR, elemental analysis (C/N content), and pHPZC. The scope of the research included, among others, research on the effect of pH (pH 2−11) on the RB5 sorption efficiency, research on sorption kinetics, and determination of the maximum sorption capacity of the tested sorbents. The sorption efficiency of RB5 on the tested sorbents was the highest at pH 2−3. The experimental data from the research on the sorption kinetics of RB5 were best described by a pseudo-second-order model. The introduction of primary amine groups to the structure of sorbents... [more]

With the integration of renewable energy sources into the power grid, a number of power electronic converters need to be connected together in parallel. Due to this interconnection among the power converters with a common DC bus, the equivalent impedance of the DC network, i.e., DC network impedance (DCNI) of these parallel converters, may vary and can cause oscillations in the DC link voltage (DCLV). In the literature, impedance models of grid-tied converters (GCs) based on the AC side are well reported without including these variations in DCNI. In addition, the dynamics of a phase-locked loop (PLL) play a significant role in GC system stability. To evaluate these stability issues, this paper proposes small signal impedance models viewing from the DC side of a three-phase GC operating under different control modes considering the PLL dynamics and the DCNI variations. Using the proposed DC impedance models (DCIM), DCLV stability analysis is evaluated for a GC. It is verified through b... [more]

To meet the expanding energy demand, all available energy sources must be utilized. Renewable energies are both eternal and natural, but their major downside is their inconsistency. Due to the rising costs of fossil fuels and the CO2 they emit, hybrid renewable energy (HRE) sources have gained popularity as an alternative in remote and rural areas. To address this issue, a hybrid renewable energy system (HRES) can be developed by combining several energy sources. In order to build modern electrical grids that have advantages for the economy, environment, and society, the hybrid system is preferable. A summary of various optimization methods (modeling techniques) of an HRES is presented in this paper. This study offers an in-depth analysis of the best sizing, control methodologies, and energy management strategies, along with the incorporation of various renewable energy sources to form a hybrid system. Modern hybrid renewable energy system utilities rely more on an optimal design to re... [more]