One of the conditions behind the development of any company is its capability of meeting the constantly changing challenges posed by the surrounding environment. Photovoltaics in Poland has been a boom industry in recent years. On 1 April 2022, new changes in photovoltaics came into force. A very short transition time will bring about serious problems to companies dealing in the photovoltaics branch since it has had an exceptionally short time to sufficiently prepare for the changes. The article presents results of a questionnaire-based survey conducted among 394 companies dealing in fitting photovoltaic installations in Poland. The subjects were selected for participation according to the purposive sample principle. The aim of the article was to present and analyze the entrepreneurs’ opinions concerning prospects for development in the nearest year to come. The alterations to the system of support of prosumers, which entered into force on 1 April 2022, will limit the interest in photo... [more]

Lean burn spark ignition (SI) engines represent an effective solution for improving fuel economy and reducing exhaust emissions and can be implemented both in conventional and hybrid powertrains. On the other hand, lean operation increases cyclic variability with negative impact on power output, engine efficiency, roughness, and operating stability. Although this phenomenon has been widely investigated, the effects of flow field on the inception and development of flames in direct injection spark ignition (DISI) engines under lean burn conditions is not yet completely understood. In particular, the effect of spark plug geometry and electrode orientation with respect to tumble motion has been minimally investigated. For these reasons, two different spark-plug geometries (i.e., single- and double-ground electrode) and three different orientations (i.e., cross-, counter-, and uni-flow with respect to the direction of tumble motion) were investigated in an optically accessible DISI engine... [more]

A fixed effects regression and two-step system generalized method of moments (GMM) is used to analyze secondary data from the World Bank, covering 163 countries over the period from 2000 to 2016. The study tests the relationship between renewable energy, urbanization, and CO2 emissions. The empirical results show that urbanization has an inverted U-shaped relationship with CO2 emissions, while renewable energy consumption mitigates CO2 emissions. If causal, a 1% increase in renewable energy use leads to a 1.2% decrease in CO2 emissions. The results also show that the GDP per capita has an inverted U-shaped relationship with CO2 emissions, confirming the environmental Kuznets curve (EKC). We also found that innovation, proxied by residents’ patents, has a non-linear effect on CO2 emissions. As a policy implication, developing countries should increase the share of renewable energy in their total energy use, and promote innovative activities by increasing government spending on R&D.

Piezoelectric energy harvesting from roadways, which converts ambient vibration energy of roads into electric energy, has a wide range of potential applications in intelligent transportation systems. On-site open-traffic tests revealed that energy harvested by piezoelectric energy harvester (PEH) units embedded in roadways is far less than the value in laboratories, which may be because the parameters of traffic flow load (frequency, distribution, wave shape, etc.) and the road structure are significantly different from the pre-established conditions in laboratories or even on-site tests with only one vehicle passing. To address this issue, an analytical model for piezoelectric energy harvesting from roadways under open-traffic conditions was proposed to examine the mechanical response of the road structure and the electrical performance of the stack PEH units embedded in the road. The influence of all parameters in the energy-harvesting system was then obtained with the scaling law me... [more]

The importance of developing efficient and environmentally friendly means of biomass conversion into bioenergy, biofuels, and valuable products is currently high in Poland. Accordingly, herein, two new energy and biofuel units are proposed, namely, POLpec and POLbp, which are used as reference sources for comparing energy consumption and biofuel production in other countries or regions in the world. One POLpec equals 4400 PJ (195.1 Mtoe), reflecting the annual primary energy consumption of Poland in 2020. Meanwhile, one POLbp equals 42 PJ (1.0 Mtoe), referring to the annual production of biofuels in Poland in 2020. Additionally, a new import−export coefficient β is proposed in the current study, which indicates the relationship between the import and export of an energy carrier. More specifically, the potential of biomass and organic waste to be converted into energy, biofuels, and valuable products has been analysed for the rural areas of Poland. Results show that the annual biomass a... [more]

A combined heating and power (CHP) microgrid has high flexibility and economy, but the output of renewable energy is uncertain. Meanwhile, excessive flexible load adjustment in the demand response process will increase user dissatisfaction. In order to solve the above problems, this paper quantifies uncertainty with the conditional value-at-risk (CVaR) of relative disturbance. Additionally, a multi-objective optimal scheduling model that takes into account both the operating economy and the demand-side power consumption satisfaction is established. In order to solve the multi-objective mixed-integer nonlinear programming problem well, we propose an improved sparrow search algorithm (ISSA), which solves the problem that the sparrow search algorithm (SSA) is prone to low accuracy, insufficient in population diversity and easy to be trapped in local optimum. Combined with the non-dominated solution ranking method, ISSA has the ability of multi-objective optimization. Finally, simulation o... [more]

In recent decades, China’s cement production has been the highest in the world, but the extensive development model, which has been formed for a long time, has brought serious damage to the natural environment. In order to promote the transformation of the production mode of China’s cement industry, this paper adopts the nonparametric frontier method to analyze the environmental efficiency of China’s cement manufacturing industry using the input−output and pollutant emission data of China’s cement manufacturing industry from 2004 to 2016. The results show that the overall environmental efficiency of China’s cement industry is low, and there is still much room for improvement. Moreover, there are serious imbalances from very low to very high between different regions. Further investigation found that during the study period, strict environmental supervision brought an average compliance cost of CNY 23.41 billion to China’s cement manufacturing industry, but the overall environmental eff... [more]

Energy production and supply are important challenges for civilisation. Renewable energy sources present an increased share of the energy supply. Under these circumstances, small-scale grids operating in small areas as fully functioning energy systems are becoming an interesting solution. One crucial element to the success of micro-grid structures is the accurate forecasting of energy consumption by large customers, such as factories. This study aimed to develop a universal forecasting tool for energy consumption by end-use consumers. The tool estimates energy use based on real energy-consumption data obtained from a factory or a production machine. This model allows the end-users to be equipped with an energy demand prediction, enabling them to participate more effectively in the smart grid energy market. A single, long short-term memory (LSTM)-layer-based artificial neural network model for short-term energy demand prediction was developed. The model was based on a manufacturing plan... [more]

This work highlights the performance metrics and the fundamental degradation mechanisms of lead-acid battery technology and maps these mechanisms to generic duty cycles for peak shaving and frequency regulation grid services. Four valve regulated lead acid batteries have been tested for two peak shaving cycles at different discharge rates and two frequency regulation duty cycles at different SOC ranges. Reference performance and pulse resistance tests are done periodically to evaluate battery degradation over time. The results of the studies are expected to provide a valuable understanding of lead acid battery technology suitability for grid energy storage applications.

Grid-compliant integration of renewable energies will in future require considerable increases in flexibility in the operation of conventional power plants. The integration of thermal energy storage systems (TES) into the power plant process can create considerable improvements, for example, in the speed of load change and partial load behavior. In the case of existing plants, there are thus good prospects of upgrading for more flexible operation, which promises improvements in the energy system that can be achieved in the relatively short term. The aim of this publication is, therefore, to identify integration options for TES in coal-fired power plants which would enable the desired high flexibility potentials and, at the same time, include cost-efficient solutions. By means of an iterative approach between future scenarios of the energy market, the power plant process, and the TES component, favored configurations were developed from a wide range of integration concepts. For this pur... [more]

This contribution presents a novel methodology to evaluate the lifetime extension potential of wind turbines—taking towers as the key component that preserves onshore turbines’ structural integrity—as a consequence of the difference between design and site-specific loads. Specifically, attention is drawn to the site-specific wind direction distribution, which provides an additional source of lifetime extension potential. For this purpose, variants of closed-form solutions (based on the tower section’s normal stress) are developed to enable fatigue damage accumulation due to fore-aft and side-to-side bending moments at any point on the tower circumference without the need for further information on tower section geometry or material properties. Based on the degree of data availability, different scenarios are defined to estimate lifetime extension potential from the accurate tower’s normal stress and approximations using resultant bending moment, fore-aft bending moment, and finally, wi... [more]

A power transformer is one of the most critical and expensive assets in electric power systems. Failure of a power transformer would not only result in a downtime to the entire transmission and distribution networks but may also cause personnel and environmental hazards due to oil leak and fire. Hence, to enhance a transformer’s reliability and extend its lifespan, a cost-effective and reliable condition monitoring technique should be adopted from day one of its installation. This will help detect incipient faults, extend a transformer’s operational life, and avoid potential consequences. With the global trend to establish digital substation automation systems, transformer online condition monitoring has been given much attention by utilities and researchers alike. Several online and offline condition monitoring techniques have been recently proposed for oil-immersed power transformers. This paper is aimed at providing a state-of-the-art review for the various condition monitoring tech... [more]

A 3D stationary CFD study was conducted in our previous work, resulting in a novel reactor design methodology oriented to upgrading biogas through CO2 methanation. To enhance our design methodology incorporating relevant power to gas operational conditions, a novel transient 3D CFD modelling methodology is employed to simulate the effect of relevant dynamic disruptions on the behaviour of a tubular fixed bed reactor for biogas upgrading. Unlike 1D/2D models, this contribution implements a full 3D shell cooled methanation reactor considering real-world operational conditions. The reactor’s behaviour was analysed considering the hot-spot temperature and the outlet CH4 mole fraction as the main performance parameters. The reactor start-up and shutdown times were estimated at 330 s and 130 s, respectively. As expected, inlet feed and temperature disruptions prompted “wrong-way” behaviours. A 30 s H2 feed interruption gave rise to a transient low-temperature hot spot, which dissipated after... [more]

The characterization of molten corium−concrete interaction (MCCI) has increasingly become a cause of concern because, in the case of a severe nuclear accident, the core could meltdown and release radiation into the environment. The objective of this study was to determine the thermochemical impact of metal content in the corium and analyze the effect of corium metal content on ablation depth, corium temperature, its viscosity and surface heat flux, and production of hydrogen, carbon monoxide, and carbon dioxide. The governing heat transfer equations were solved while considering the various thermochemical reactions in the existing numerical code in a comprehensive way. The developed MCCI model in CORQUENCH was validated against the data available in the literature. Our findings showed that the composition of corium, especially its metal content, has a noticeable effect on mitigating or aggravating the ablation depth and nuclear reactor integrity. We observed that during molten corium−c... [more]

Hydraulic vibration is a critical factor affecting the stability and health of the hydro-turbine generator unit (HGU). This paper investigates the nonlinear dynamic characteristics of the HGU occurring from the hydraulic vibration. First, using the turbulence flow model, the lift and drag coefficients of the asymmetric airfoil blades are calculated at different Reynolds numbers and angles of attack. Based on the lift and drag coefficients of the asymmetric airfoil blade, a novel nonlinear mathematical model of asymmetric hydraulic forces is proposed for the asymmetric airfoil blade. Then, combining mechanic and electric asymmetric excitations, a coupled nonlinear mathematical model of the HGU is built using Lagrange equations. Moreover, the correctness of this model is verified. Finally, dynamic behaviors of the HGU changing with attack angle, deviation of the outlet blade angle, outlet guide vane angle, and Reynolds number are analyzed by bifurcation diagrams. It is found that increas... [more]

The environmental context causes the use of renewable energy to increase, with the aim of finding alternatives to fossil-based products such as fuels. Biodiesel, an alternative to diesel, is now a well-developed solution, and its production from renewable resources makes it perfectly suitable in the environmental context. In addition, it is biodegradable, non-toxic and has low greenhouse gas emissions: reduced about 85% compared to diesel. However, the feedstock used to produce biodiesel competes with agriculture and the application of chemical reactions is not advantageous with a “green” process. Therefore, this review focuses only on bioprocesses currently taking an important place in the production of biodiesel and allow high yields, above 90%, and with very few produced impurities. In addition, the use of waste oils as feedstock, which now accounts for 10% of feedstocks used in the production of biodiesel, avoids competition with agriculture. To present a complete life-cycle of oil... [more]

The current need for power-system control-room operational tools to increase real-time situational awareness has led to various proposals on data analytics algorithms to obtain operational information from SCADA and PMU power system networks. Most of the proposals are implemented in simulation, with reduced practical significance for system operators. This work proposes a web-based simple algorithm to identify the dynamic parameters of a reduced-order model of power system frequency dynamics that is implemented with industrial hardware on a PMU network in the Chilean power system. To demonstrate the applicability of the proposed tool, the algorithm is implemented in a web page with real-time monitoring of the frequency of the Chilean power system, so that utilities and academic institutions with access to PMU measurements can apply the proposed concepts regardless of the topology of the monitored system.

Work processes and sociological structures can differ significantly between organizations. These organizational aspects determine user behavior, which in turn exerts considerable influence on the key performance indicators of artificial lighting systems. Accordingly, the use of generalized assumptions about user behavior in the building design phase can lead to large discrepancies between design and operation. In the following work, the possible influences of different occupancy schemes, an essential aspect of user behavior and shaped by the organization, on energy demand and workplace-related daylight dose are evaluated. For this purpose, calculations are made based on real measurement data of an open-plan office with zoned lighting. Multi-level calculation models are used to determine improved user distributions in the room to ensure optimization according to the desired target criteria. The results show that occupancy schemes have a significant impact on energy demand, contributing... [more]

This study investigated the effects of polyvinyl chloride (PVC) addition on low-rank coal’s pyrolysis characteristics, especially the products distribution and chlorine migration. Hailar lignite (HLE) with different industrial, pure, PVC-content additions were prepared (the mass percentage of PVC addition was from 5% to 25%), and the co-pyrolysis characteristics of HLE and PVC were performed on a fixed-bed reactor and thermogravimetric analyzer. The chars were characterized with X-ray diffraction (XRD), X-ray fluorescence (XRF), and Fourier-transform infrared (FT-IR) spectroscopy analysis. The gas and tar compositions were analyzed by using gas chromatography (GC) and a gas chromatography−mass spectrometry (GC−MS) system, respectively. The results indicate that the addition of PVC can increase the release amounts of CH4, C2H4, and C2H6, simultaneously reducing the release amount of CO2 and CO; the quality of pyrolysis tar was also improved, especially the alkane content in tar, which i... [more]

The requirement for clean energy has increased drastically over the years due to the emission of CO2 and the degrading of the environment by introducing Renewable Energy Systems (RES) into the existing power grid. While these systems are a positive change, they come at a cost, with some issues relating to the stability of the grid and feasibility. Hence, this research paper closely investigates the modeling and interlinking of photovoltaic (PV)-based solar power and Double-Fed Induction Generator (DFIG)-based wind turbines with the conventional power systems. RES has been known to contribute to a highly non-linear system and complexity. To return the power systems to their original state after a load disturbance, a novel control technique based on the fractional-order Type-2 Fuzzy logic system, well developed via particle swarm optimization (PSO), has been utilized for solving the frequency control problem of a renewable interlinked power system. The efficacy of the proposed technique... [more]

Wearable thermoelectric generators (WTEGs) can incessantly convert body heat into electricity to power electronics. However, the low efficiency of thermoelectric materials, tiny terminal temperature difference, rigidity, and neglecting optimization of lateral heat transfer preclude WTEGs from broad utilization. In this review, we aim to comprehensively summarize the state-of-the-art strategies for the realization of flexibility and high normalized power density in thermoelectric generators by establishing the links among materials, TE performance, and advanced design of WTEGs (structure, heatsinks, thermal regulation, thermal analysis, etc.) based on inorganic bulk TE materials. Each section starts with a concise summary of its fundamentals and carefully selected examples. In the end, we point out the controversies, challenges, and outlooks toward the future development of wearable thermoelectric devices and potential applications. Overall, this review will serve to help materials scie... [more]

Recently, we demonstrated for Curaçao that renewable electricity generation from wind combined with energy storage in the form of ammonia is competitive with imported fossil fuels, such as LNG, oil, and coal. In the current work, we have expanded the model by considering imported green ammonia as an alternative to local electricity generation and storage. Local production of ammonia as an energy storage medium was compared with imported ammonia to make up the electricity produced from onshore wind, for Curaçao and Fiji’s largest island Viti Levu. Curaçao and Viti Levu have been selected as two interesting extremes with favorable and non-favorable wind conditions, respectively. Assuming a market price of 500 USD/t NH3, it is found that importing ammonia is the most feasible solution for both islands, with a levelized cost of electricity (LCOE) of 0.11 USD/kWh for Curaçao and 0.37 USD/kWh for Viti Levu. This compares to 0.12 USD/kWh for Curaçao; however, for Viti Levu, this value increas... [more]

This paper is devoted to solving the problem of how to comprehensively control coal seam gas and hydrogen sulfide in the mining face, distributed from the coal seam in abandoned oil wells in coal mining resource areas. The abandoned oil wells of Ma tan 30 and Ma tan 31 in the No. I0104105 working face of the Shuang Ma Coal Mine were taken as examples. Through parameter testing, gas composition analysis, field investigation at the source distribution, and the influence range of gas and hydrogen sulfide in coal seam in the affected range of the abandoned oil wells were studied. The results show that the coal-bearing strata in Shuang Ma coal field belong to the coal−oil coexistence strata, and the emission of H2S gas in the local area of the working face is mainly affected by closed and abandoned oil wells. Within the influence range of the abandoned oil wells, along the direction of the working face, the concentration of CH4 and H2S gas in the borehole increases as you move closer to the... [more]

Typhoons are a serious threat to transmission towers and lines in coastal areas. The anti-wind performance of a transmission tower needs to be reinforced and optimized to avoid tower collapse. Here, an improved real-time wind-field mathematical model and a tower-line coupled simulation model were established to reproduce the wind field distribution, mechanical vibration, and interaction between the wind field and tower. The damage prediction of the transmission tower was analyzed. Furthermore, an actual scaled tower-line model was built, which was used to measure the acceleration and displacement responses in the anti-wind experiments. The research results show that the improved model is feasible and correct based on the verification of Typhoon Mujigae. The tower’s vibration response is mainly characterized by low frequencies, whereas the lines indicate a high frequency response. The transmission line has a remarkable impact on tower vibrations in high turbulence. A flow direction angl... [more]

Layered Na0.8Co0.8Ti0.2O2 oxide crystallizes in the β-RbScO2 structure type (P2 modification) with Co(III) and Ti(IV) cations sharing the same crystallographic site in the metal-oxygen layers. It was synthesized as a single-phase material and characterized as a cathode in Na- and Na-ion batteries. A reversible capacity of about 110 mA h g−1 was obtained during cycling between 4.2 and 1.8 V vs. Na+/Na with a 0.1 C current density. This potential window corresponds to minor structural changes during (de)sodiation, evaluated from operando XRD analysis. This finding is in contrast to Ti-free NaxCoO2 materials showing a multi-step reaction mechanism, thus identifying Ti as a structure stabilizer, similar to other layered O3- and P2-NaxCo1−yTiyO2 oxides. However, charging the battery with the Na0.8Co0.8Ti0.2O2 cathode above 4.2 V results in the reversible formation of a O2-phase, while discharging below 1.5 V leads to the appearance of a second P2-layered phase with a larger unit cell, which... [more]