This research investigates the impact of oil price, income and carbon dioxide emissions on renewable energy consumption in Russia for the data period from 1990 to 2015, using the Vector Error Correction Models and the Canonical Cointegrating Regression method. This article is the only study conducting individual time-series analysis that emphasizes the effect of oil price on renewable energy consumption in the case of Russia. The results of empirical analysis conclude that oil price affects renewable energy consumption negatively. The negative oil price effects on renewable energy use can be interpreted as a sign of issue that stems from higher oil prices and slows the transition from conventional to renewable energy sources. Additionally, we found that there is a positive and statistically significant influence of real GDP per capita as a proxy of income on renewable energy consumption, whereas the carbon dioxide emissions have a negative and statistically insignificant influence on r... [more]

To further understand the problems of coal combustion and coalfield fire reignition, this paper researched the reaction characteristics of coal pyrolysis and low oxygen combustion and the reburning oxidation characteristics of residual structure by thermal analysis methods. The results show that temperature promotes both pyrolysis and low oxygen combustion reactions, but low oxygen combustion reaction is more sensitive to temperature changes. As the constant temperature rises, the mass reduction rate of low oxygen combustion of coal samples reaches 80% on average, which is 4 times that of pyrolysis, and the variations of thermogravimetric parameters are also significantly higher than those of pyrolysis. However, the higher the pyrolysis degree of the residues, the stronger their oxidizability, which greatly enhances the intensity and concentration of the secondary combustion, and the mass of residues is reduced by 90% on average. Conversely, because the combustible components are conti... [more]

The main objective of this study was assessment of the performance, emissions and combustion characteristics of a diesel engine using RME−1-butanol blends. In assessing the combustion process, great importance was placed on evaluating the stability of this process. Not only were the typical COVIMEP indicators assessed, but also the non-burnability of the characteristic combustion stages: ignition delay, time of 50% heat release and the end of combustion. The evaluation of the combustion process based on the analysis of heat release. The tests carried out on a 1-cylinder diesel engine operating at a constant load. Research and evaluation of the combustion process of a mixture of RME and 1-butanol carried out for the entire range of shares of both fuels up to 90% of 1-butanol energetic fraction. The participation of butanol in combustion process with RME increased the in-cylinder peak pressure and the heat release rate. With the increase in the share of butanol there was noted a decrease... [more]

The use of renewable energy sources and carbon emissions has been debated from various perspectives throughout recent decades. However, the causal relationship between green energy sources and carbon emissions volatility has received limited attention. This study aims to close a knowledge gap in this area. The current study analyzes the renewable energy sources (wind, hydro, and geothermal) and carbon emissions of four ASEAN countries (Indonesia, Thailand, Vietnam, and the Philippines) between 2000 and 2019. The present study combined Chudik and Pesaran’s (2015) newly developed Dynamic Common Correlated Effects (DCCE) with cutting-edge investigation tools such as first- and second-generation unit root tests; CS-dependence; Variance inflation factor test for multicollinearity; and Pedroni, Kao, and Wester Lund tests of co-integration. The Granger causality test is also used to check the short-term and long-term causal effects within the renewable energy sources and green energy sources,... [more]

In this work, copper oxides-based photocathodes for photoelectrochemical cells (PEC) were produced for the first time by screen printing. A total 7 × 10−3 g/m2 glycerine trioleate was found as optimum deflocculant amount to assure stable and homogeneous inks, based on CuO nano-powder. The inks were formulated considering different binder amounts and deposited producing films with homogenous thickness, microstructure, and roughness. The as-produced films were thermally treated to obtain Cu2O- and Cu2O/CuO-based electrodes. The increased porosity obtained by adding higher amounts of binder in the ink positively affected the electron transfer from the surface of the electrode to the electrolyte, thus increasing the corresponding photocurrent values. Moreover, the Cu2O/CuO system showed a higher charge carrier and photocurrent density than the Cu2O-based one. The mixed Cu2O/CuO films allowed the most significant hydrogen production, especially in slightly acid reaction conditions.

This paper presents a comparison of the 24-month production of electricity and momentary power by two photovoltaic systems with a nominal power of 1000 Wp each. The analyzed systems are connected to the power grid and operate independently: a fixed system with optimal all-year-round angular positioning and an astronomical-sensor-controlled dual-axis tracking system. The systems under consideration consist of PV modules with a unit electrical power of 200 Wp, and the production technology of those modules is the same. The tested systems were located on the building rooftop of the Faculty of Control, Robotics and Electrical Engineering of the Poznan University of Technology in Poland (Central Poland, 52°24.4152′ N, 16°55.7958′ E) at a height of 30 m above ground level. The measurements take into account the consumption of electricity by the actuators of the dual-axis positioning system. Increases in the produced electricity by 35.6% and 44.7% were observed for local climatic conditions d... [more]

The purpose of this study is to utilize two artificial intelligence (AI) models to predict the syngas composition of a fixed bed updraft gasifier for the gasification of rice husks. Air and steam-air mixtures are the gasifying agents. In the present work, the feeding rate of rice husks is kept constant, while the air and steam flow rates vary in each case. The consideration of various operating conditions provides a clear comparison between air and steam-air gasification. The effects of the reactor temperature, steam-air flow rate, and the ratio of steam to biomass are investigated here. The concentrations of combustible gases such as hydrogen, carbon monoxide, and methane in syngas are increased when using the steam-air mixture. Two AI models, namely artificial neural network (ANN) and gradient boosting regression (GBR), are applied to predict the syngas compositions using the experimental data. A total of 74 sets of data are analyzed. The compositions of five gases (CO, CO2, H2, CH4,... [more]

Demand Response (DR) programs represent an effective way to optimally manage building energy demand while increasing Renewable Energy Sources (RES) integration and grid reliability, helping the decarbonization of the electricity sector. To fully exploit such opportunities, buildings are required to become sources of energy flexibility, adapting their energy demand to meet specific grid requirements. However, in most cases, the energy flexibility of a single building is typically too small to be exploited in the flexibility market, highlighting the necessity to perform analysis at a multiple-building scale. This study explores the economic benefits associated with the implementation of a Reinforcement Learning (RL) control strategy for the participation in an incentive-based demand response program of a cluster of commercial buildings. To this purpose, optimized Rule-Based Control (RBC) strategies are compared with a RL controller. Moreover, a hybrid control strategy exploiting both RBC... [more]

The development of a transition-metal-based catalyst with concomitant high activity and stability due to its distinguishing characteristics, yielding an abundance of active sites, is considered to be the bottleneck for the dry reforming of methane (DRM). This work presents the catalytic activity and durability of SrNiO3 and CeNiO3 perovskites for syngas production via DRM. CeNiO3 exhibits a higher specific surface area, pore volume, number of reducible species, and nickel dispersion when compared to SrNiO3. The catalytic activity results demonstrate higher CH4 (54.3%) and CO2 (64.8%) conversions for CeNiO3, compared to 22% (CH4 conversion) and 34.7% (CO2 conversion) for SrNiO3. The decrease in catalytic activity after replacing cerium with strontium is attributed to a decrease in specific surface area and pore volume, and nickel active sites covered with strontium carbonate. The stability results reveal the deactivation of both the catalysts (SrNiO3 and CeNiO3) but SrNiO3 showed more d... [more]

The transition to oxy-fuel combustion power cycles is a prospective way to decrease carbon dioxide emissions into the atmosphere from the energy sector. To identify which technology has the highest efficiency and the lowest emission level, a thermodynamic analysis of the semiclosed oxy-fuel combustion combined cycle (SCOC-CC), the E-MATIANT cycle, and the Allam cycle was carried out. The modeling methodology has been described in detail, including the approaches to defining the working fluid properties, the mathematical models of the air separation unit, and the cooled gas turbine cycles’ calculation algorithms. The gas turbine inlet parameters were optimized using the developed modeling methodology for the three oxy-fuel combustion power cycles with CO2 recirculation in the inlet temperature at a range of 1000 to 1700 °C. The effect of the coolant flow precooling was evaluated. It was found that a decrease in the coolant temperature could lead to an increase of the net efficiency up t... [more]

Distributed thermal energy storage (DTES) provides specific opportunities to realize the sustainable and economic operation of urban electric heat integrated energy systems (UEHIES). However, the construction of the theory of the model and the configuration method of thermal storage for distributed application are still challenging. This paper analyzes the heat absorption and release process between the DTES internal heat storage medium and the heat network transfer medium, refines the relationship between heat transfer power and temperature characteristics, and establishes a water thermal energy storage and electric heater phase change thermal energy storage model, considering medium temperature characteristics. Combined with the temperature transmission delay characteristics of a heat network, a two-stage optimal configuration model of DTES for UEHIES is proposed. The results show that considering the temperature characteristics in the configuration method can accurately reflect the... [more]

An investigation of the fuel heating, vapor formation, and cavitation erosion location patterns inside a five-hole common rail diesel fuel injector, occurring during the early opening period of the needle valve (from 2 μm to 80 μm), discharging at pressures of up to 450 MPa, is presented. Numerical simulations were performed using the explicit density-based solver of the compressible Navier−Stokes (NS) and energy conservation equations. The flow solver was combined with tabulated property data for a four-component diesel fuel surrogate, derived from the perturbed chain statistical associating fluid theory (PC-SAFT) equation of state (EoS), which allowed for a significant amount of the fuel’s physical and transport properties to be quantified. The Wall Adapting Local Eddy viscosity (WALE) Large Eddy Simulation (LES) model was used to resolve sub-grid scale turbulence, while a cell-based mesh deformation arbitrary Lagrangian−Eulerian (ALE) formulation was used for modelling the injector’... [more]

One key directive to realize the global transition towards net-zero emission goals is to integrate more renewable energy resources into the generation mix. Due to higher and more consistent wind speeds, offshore wind farms (OWFs) have the potential to generate more energy at a steadier rate than their onshore counterpart. However, at the collection system level, all the OWFs use alternating current (AC) technology at present. Nonetheless, with an increasing capacity of the single wind turbine (WT) and larger distances to the shore, the use of direct current (DC) technology at the collection system level is beneficial. To select a suitable DC collection system topology, this paper proposes a comprehensive analytical reliability evaluation method, based on the Universal Generating Function technique, together with associated economic factors. Four candidates DC collection system options were evaluated with different WT capacities for a 400 MW OWF. The availability indices such as Generat... [more]

Savonius rotors are large and heavy because they use drag force for propulsion. This leads to a larger investment in comparison to horizontal axis wind turbine (HAWT) rotors using lift forces. A simple construction of the Savonius rotor is preferred to reduce the production effort. Therefore, it is proposed here to use single-segment rotors of high elongation. Nevertheless, this rotor type must be compared with a multi-segment rotor to prove that the simplification does not deteriorate the effectiveness. The number of segments affects the aerodynamic performance of the rotor, however, the results shown in the literature are inconsistent. The paper presents a new observation that the relation between the effectiveness of single- and multi-segment rotors depends on the wind velocity. A single-segment rotor becomes significantly more effective than a four-segment rotor at low wind speeds. At high wind speeds, the effectiveness of both rotors becomes similar.

Compression ignition (CI) engines are popular in the transport sector because of their high compression ratio. However, in recent years, it has become a major concern from an environmental point of view because of the emission and depleting fossil fuel. The advanced combustion concept has been a popular research topic in the CI engine. Low-temperature combustion with alternate fuel has helped in reducing the oxides of nitrogen (NOx) and soot emission of the engine. Biogas is a popular substitute of energy especially deduced from biomass because of its clean combustion properties, as well it being a renewable energy source compared to non-renewable diesel resources. In experiments with dual fuel, i.e., conventional diesel and alternate fuel (biogas) were carried out through them. In the present study, an artificial neural network model was used to estimate emissions and check the attributes of performance. Different algorithms and training functions were used to train the models. Howeve... [more]

The correct operation of the continuous welded track requires diagnosing its condition and preparation of track metrics requiring measurements of displacements of rail under operation. This is required as there are additional thermal stresses in the rails with values depending on the temperature changes of the rails. Therefore, the climatic conditions are important. This paper presents the original effective analytical method for diagnosing the condition of continuous welded track based on experimental research. The method allows for an appropriate repair or maintenance recommendation. In the experimental research, the authors considered track diagnostic conditions for two conditions: track under load and track without load. This paper presents empirical formulas for calculating rail temperature and longitudinal force based on ambient temperature, developed from long-term measurements. The formulas were developed for a track located on a straight section—both for a rail loaded and unlo... [more]

The purpose of the research was to identify the factors determining the improvement of the sustainable energy management strategy in the process of building lasting value for stakeholders, identifying key activities supporting the process of improving the sustainable energy management strategy, and analyzing the degree of use of environmental indicators by organizations in Poland. In the research process, to achieve the assumed research goals, it was decided to use the following research methods: The “Delphic Method” and the CAWI method (Computer-Assisted Web Interview). The research was carried out on a sample of 102 organizations in Poland. The study identifies goals for the sustainable development of the organization, activities supporting the process of sustainable energy management, and indicators in the field of energy management. The key factors for the improvement of energy management strategies have been identified, including implementation of modern technologies, reduction of... [more]

The optimal state of charge (SoC) balancing control for series-connected lithium-ion battery cells is presented in this paper. A modified SoC balancing circuit for two adjacent cells, based on the principle of a bidirectional Cuk converter, is proposed. The optimal SoC balancing problem is established to minimize the SoC differences of cells and the energy loss subject to constraints of the normal SoC operating range, the balancing current, and current of cells. This optimization problem is solved using the sequential quadratic programming algorithm to determine the optimal duties of PWM signals applied to the SoC balancing circuits. An algorithm for the selection of the initial points for the optimal problem-solving process is proposed. It is applied in cases where the cost function has no decreasing part. Experimental tests are conducted for seven series-connected Samsung cells. The optimal SoC balancing control and SoC estimation algorithms are coded in MATLAB and embedded in LabVIE... [more]

The development of internal combustion engines is currently based around the ideas of downsizing and rightsizing. These trends, however, are not very widespread in vehicles with hybrid drive systems. Nevertheless, the authors analyzed the performance indicators of hybrid drives in downsized vehicles. Two generations of a vehicle model, equipped with hybrid drive systems, were used in the analysis in which not only the design of the internal combustion engine was changed, but also other hybrid drive systems (including the transmission, electric motors and high-voltage batteries). The paper analyzes the energy flow in two hybrid vehicles of different generations during tests in real road driving conditions in accordance with the requirements of the RDE (real driving emissions) tests. The authors have confirmed that newer vehicle designs extend the vehicle range by 38% in the electric mode under the conditions of road traffic (68% in the urban conditions). The application of a combustion... [more]

An improved thermodynamic open Dual cycle is proposed to simulate the working of internal combustion engines. It covers both spark ignition and Diesel types through a sequential heat release. This study proposes a procedure that includes (i) the composition change caused by internal combustion, (ii) the temperature excursions, (iii) the combustion efficiency, (iv) heat and pressure losses, and (v) the intake valve timing, following well-established methodologies. The result leads to simple analytical expressions, valid for portable models, optimization studies, engine transformations, and teaching. The proposed simplified model also provides the working gas properties and the amount of trapped mass in the cylinder resulting from the exhaust and intake processes. This allows us to yield explicit equations for cycle work and efficiency, as well as exhaust temperature for turbocharging. The model covers Atkinson and Miller cycles as particular cases and can include irreversibilities in co... [more]

In many areas in the world, the high voltage (HV) electricity grid is saturated, which makes it difficult to accommodate additional solar photovoltaic (PV) systems connection requests. In this paper, different scenarios to increase the installed PV capacity in a saturated grid are assessed on the basis of the net present value (NPV). The developed scenarios compare an increase of grid capacity, PV system azimuth variation, curtailment, and battery storage. For each scenario the net present value (NPV) is assessed using an optimization model as a function of the overbuild capacity factor, which is defined as the relative amount of PV capacity added beyond the available capacity. The scenarios are applied on a case study of the Netherlands, and the analysis shows that, by optimising curtailment, a PV system’s capacity can be increased to 120% overbuild capacity. For larger overbuild capacity investments in the electricity-grid are preferred when these costs are taken into account. Howeve... [more]

The restriction on the battery life of sensors is a bottleneck for wireless sensor networks (WSNs). This paper proposes a new feed-forward multi-clustering protocol (FFMCP) to boost the network lifetime. The utilization of fuzzy logic helps to overcome the uncertainties in the value of input parameters. The proposed protocol selects the most suitable cluster heads (CHs) using the multi-clustering method. A multi-clustering technique is defined utilizing the node’s information of the previous round and a fuzzy inference system to decide the CHs. The sensor nodes spend energy due to non-uniform CH distribution and long-distance data transmission by member nodes. The main focus of the proposed protocol is to reduce the member node distance. Our proposal distributes CH nodes uniformly using unequal clustering. The simulation outcome reveals that the proposed algorithm(FFMCP) has better performance in terms of tenth node death (TND), half node death (HND), remaining energy after 800 rounds... [more]

Biomass with a large amount of moisture is well-suited to be processed by supercritical water gasification, SCWG. The precipitation of inorganics, together with char formation and re-polymerization, can cause reactor plugging and stop the process operations. When plugging occurs, sudden injections of relatively large mass quantities take place, influencing the mass flow dynamics significantly in the process. Reactor plugging is a phenomenon very well observed during SCWG of industrial feedstock, which hinders scale-up initiatives, and it is seldom studied with precision in the literature. The present study provides an accurate evaluation of continuous tubular reactor dynamics in the event of sudden injections of water. An interpretation of the results regarding water properties at supercritical conditions contributes to comprehending mass and heat transfer when plugging occurs. Experiments are then compared to SCWG of a biomass sample aiming to give key insights into heat transfer and... [more]

Renewable Energy Sources (RES) have become increasingly desirable worldwide in the fight against global climate change. The sharp decrease in costs of especially wind and solar photovoltaics (PV) have created opportunities to move from dependency on conventional fossil fuel-based electricity production towards renewable energy sources. Renewables experience around 7% (in 2018) annual growth rate in the electricity production globally and the pace is expected to further increase in the near future. Cuba is no exception in this regard, the government has set an ambitious renewable energy target of 24% RES of electricity production by the year 2030. The article analyses renewable energy trajectories in Isla de la Juventud, Cuba, through different future energy scenarios utilizing EnergyPLAN tool. The goal is to identify the best fit and least cost options in transitioning towards 100% electric power systemin Isla de la Juventud, Cuba. The work is divided into analysis of (1) technical pos... [more]

Salt caverns are accepted as an ideal solution for high-pressure hydrogen storage. As well as considering the numerous benefits of the realization of underground hydrogen storage (UHS), such as high energy densities, low leakage rates and big storage volumes, risk analysis of UHS is a required step for assessing the suitability of this technology. In this work, a preliminary quantitative risk assessment (QRA) was performed by starting from the worst-case scenario: rupture at the ground of the riser pipe from the salt cavern to the ground. The influence of hydrogen contamination by bacterial metabolism was studied, considering the composition of the gas contained in the salt caverns as time variable. A bow-tie analysis was used to highlight all the possible causes (basic events) as well as the outcomes (jet fire, unconfined vapor cloud explosion (UVCE), toxic chemical release), and then, consequence and risk analyses were performed. The results showed that a UVCE is the most frequent ou... [more]