The article discusses the analysis of the possible development of hazards associated with the operation of vehicles equipped with an electric drive using the example of passenger cars. The authors review the problem of the safety of people and property resulting from the occurrence of a fire in an electric passenger car, in the context of fires that have occurred in recent years. Particular attention was paid to the analysis of the state of knowledge concerning the characteristics of the fire progression in an electric car, its heat release rate curve [HRR], total heat release [THR], heat of combustion and factors affecting the fire progression. In this paper, an attempt was made to compare the fire characteristics of an electric car and a passenger car equipped with an internal combustion engine together with an estimation, using CFD simulations, of the impact on the safety of people and property in closed structures such as underground garages or road tunnels. The need for further de... [more]

A new EGS arrangement, Robust EGS (REGS), is studied for its potential benefits for wide-spread applications for clean, carbon-free, electrical energy generation. Numerical simulations are carried out to prove the key benefit of REGS in a simple, but effective, geologic heat exchanger arrangement with large, stabilized fracture aperture and controlled flow zones. The numerical model results show the estimated potential energy capacity and the converted value to electrical energy generation over a 30-year operation time period for two simple REGS arrangements. The results may assist EGS investors and drilling companies in deciding whether the investment and operation can be made profitable for the wide-scale application of REGS for green energy generation.

This paper focuses on the state-of-the-art of unit commitment (UC) and economic dispatch (ED) algorithms suitable for the Italian electricity market. In view of the spread of renewable energy systems (RES), the desired UC algorithm should be able to properly consider the uncertainty affecting key input variables into the formulation of the problem, as well as the different capabilities of dispatched power plants to provide ancillary services (e.g., voltage regulation). The goal of this paper is to resume the developments in UC and ED algorithms which occurred in the last decades, having a particular focus on alternating current (AC) security constrained (SC) approaches and stochastic ones, highlighting the advantages and weakness of each technique. This review is useful for the Italian TSO (Terna) to investigate what is the best solution to formulate a new algorithm to be potentially adopted in the framework of the Italian Ancillary Service Market, striving for an explicit modelization... [more]

Energy policy affects the functioning of the economic and financial systems of countries worldwide. This paper provides a theoretical overview of the economy−energy nexus and discusses the particular cases of the energy policy dynamics amid the sustainability goals. This paper integrates multiple perspectives on the energy−economy nexus, with a particular focus on the energy trilemma, 4As of energy security and PESTEL approach. This allows the development of a comprehensive framework for the analysis of energy security and the sustainability interaction. A review of manifestations of the different dimensions of energy security and sustainability is carried out to identify the most topical facets of the issue. Then, the cases of the selected European Union countries (Ireland, Greece, Denmark and Lithuania) are presented to highlight the effects and features of the recent energy policy changes there. Indeed, these countries apply a PSO levy mechanism on electricity tariffs and are divers... [more]

Offshore wind energy has been identified as one of the most promising and increasingly attractive sources of energy. This technology offers a long-term power-generation source, less environmental impact, and fewer physical restrictions. However, given the complexity of this technology, economic feasibility studies are essential. Thus, this study aims to identify the main trends and criteria or the methods used in the economic feasibility studies of offshore wind energy, providing a review of the state of the art in this literature. For this, a Systematic Literature Review was carried out. The article shows the growing interest in offshore wind power generation and highlights how recently the interest in the studies that assess the technical−economic feasibility of this source has grown; it presents the main milestones of the topic. Based on a structured literature review, this article identifies the main trends in this topic: (i) wind farms, (ii) risk, (iii) floating offshore wind farm... [more]

Emissions from heavy-duty vehicles need to be reduced to decrease their impact on the climate and to meet future regulatory requirements. The use of a cost-optimized thermoelectric generator based on total cost of ownership is proposed for this vehicle class with natural gas engines. A holistic model environment is presented that includes all vehicle interactions. Simultaneous optimization of the heat exchanger and thermoelectric modules is required to enable high system efficiency. A generator design combining high electrical power (peak power of about 3000 W) with low negative effects was selected as a result. Numerical CFD and segmented high-temperature thermoelectric modules are used. For the first time, the possibility of an economical use of the system in the amortization period of significantly less than 2 years is available, with a fuel reduction in a conventional vehicle topology of already up to 2.8%. A significant improvement in technology maturity was achieved, and the powe... [more]

The need for environmental protection is pushing to a massive introduction of energy production from renewables. Although wind and solar energy present the most mature technologies for energy generation, wave energy has a huge annual energy potential not exploited yet. Indeed, no leading device for wave energy conversion has already been developed. Hence, the future exploitation of wave energy will be strictly related to a specific infrastructure for power distribution and transmission that has to satisfy high requirements to guarantee grid safety and stability, because of the stochastic nature of this source. To this end, an electrical architecture model, based on a common DC bus topology and including a Hybrid Energy Storage System (HESS) composed by Li-ion battery and flywheel coupled to a wave energy converter, is here presented. In detail, this research work wants to investigate the beneficial effects in terms of voltage and current waveforms frequency and transient behavior at th... [more]

Geographic Information Systems (GIS) and Remote Sensing (RS) techniques are of great interest for the renewable energy field [...]

The operation of various types of turbomachines is importantly affected by sediment erosion. Francis turbines used for power generation typically suffer said effects due to the fact that they are used in sediment-laden rivers and are usually operated disregarding the long-term effect of the erosion on turbine performance. This investigation seeks to study the erosion rate for the main components of the turbines located at San Francisco hydropower plant in Pastaza, Ecuador. A sediment characterization study was performed in order to determine the properties of the particles present in Pastaza River and accurately predict their effect on the turbine flow passages. A numerical approach combining liquid−solid two-phase flow simulation and an erosion model was used to analyze the erosion rates at different operating conditions and determine wear patterns in the components. As expected, the results indicated that an increase in the erosion rate was obtained for higher intake flows. However,... [more]

This paper discusses the application of robust control techniques to a smart grid (SG) in order to find more powerful and suitable control tools to guarantee SG robustness. Two key aspects are in particular discussed. The first one relates to the need of a suitably model for the SG. The second one relates to the selection of an appropriate robust control technique to guarantee rejection of the adverse effects caused by mutual interactions among control loops and model uncertainty. The final purpose is to bridge the gap between the power of robust control theorems and the reality of SG operations.

The voltage and current ripples in the three-level bi-directional converter (TLBC) can be reduced by an interleaving technique that controls a phase difference between the modules of power converter. On the other hand, the inductor current ripple in TLBC is increased due to the circulating current between the modules. In this paper, the effects of two interleaving methods on a two-phase TLBC, Z-type and N-type, are investigated and compared. In particular, capacitor current ripple, and voltage ripple are compared by two interleaving methods verified through Powersim (PSIM) simulation.

In addition to zero-carbon generation, the plummeting cost of renewable energy sources (RES) is enabling the increased use of distributed-generation sources. Although the RES appear to be a cheaper source of energy, without the appropriate design of the RES with a true understanding of the nature of the load, they can be an unreliable and expensive source of energy. Limited research has been aimed at designing small-scale hybrid energy systems for irrigation pumping systems, and these studies did not quantify the water requirement, or in turn the energy required to supply the irrigation water. This paper provides a comprehensive feasibility analysis of an off-grid hybrid renewable energy system for the design of a water-pumping system for irrigation applications in Sudan. A systematic and holistic framework combined with a techno-economic optimization analysis for the planning and design of hybrid renewable energy systems for small-scale irrigation water-pumping systems is presented. D... [more]

Despite the potential in single- and multi-junction solar cells application, research into the wide band gap CuIn1−xGax(Se1−ySy)2 or CIG(SSe)2 solar cell material, with Eg≥1.5eV, has yet to be extensively performed to date. In this work, we conducted a numerical study into the role of the n-type layers in CIG(SSe)2 heterojunction solar cells, specifically concerning the maximum open-circuit voltage of the devices. In the first part of the study, we derived a new ideal open-circuit voltage equation for a thin-film heterojunction solar cell by taking into account the current contribution from the depletion region. The accuracy of the new equation was validated through a simulation model in the second part of the study. Another simulation model was also used to clarify the design rules of the n-type layer in a wide band gap CIG(SSe)2 solar cell. Our work stressed the importance of a positive conduction band offset on the n-/p-type interface, through the use of a low electron affinity n-ty... [more]

The increase in intermittent renewable energy resources and distributed generation has led to the need for developing new controllers and management techniques for smart grids [...]

Croatian energy strategy defines ambitious goals aimed at achieving energy transition toward a sustainable low-carbon society. Achieving those goals requires significant investments in the renewable energy sources and improved energy efficiency of buildings. The purpose of this paper is to estimate and compare the economic effects of the energy transition on the renewable energy supply and demand side. The estimation of the energy transition effects in Croatia in the period 2020−2050 is based on the input-output model, which identifies direct, indirect and induced effects of investments in renewable energy sources and energy efficient buildings renovation. Results of the study reveal relatively higher gross value added and employment effects induced by investments in building retrofits, but the effects of investments in renewable energy are also significant. Investments in sustainable, efficient and environmentally effective energy system could significantly contribute to Croatian GDP.... [more]

Bio-char has the ability to isolate carbon in soils and concurrently improve plant growth and soil quality, high energy density and also it can be used as an adsorbent for water treatment. In the current work, the characteristics of four different types of bio-chars, obtained from slow pyrolysis at 375 °C, produced from hard-, medium-, thin- and paper-shelled walnut residues have been studied. Bio-char properties such as proximate, ultimate analysis, heating values, surface area, pH values, thermal degradation behavior, morphological and crystalline nature and functional characterization using FTIR were determined. The pyrolytic behavior of bio-char is studied using thermogravimetric analysis (TGA) in an oxidizing atmosphere. SEM analysis confirmed morphological change and showed heterogeneous and rough texture structure. Crystalline nature of the bio-chars is established by X-ray powder diffraction (XRD) analysis. The maximum higher heating values (HHV), high fixed carbon content and... [more]

Carbon neutrality is a goal the world is striving to achieve in the context of global warming. Carbon capture and storage (CCS) has received extensive attention as an effective method to reduce carbon dioxide (CO2) in the atmosphere. What follows is the migration pathway and leakage monitoring after CO2 injection. Interferometric synthetic aperture radar (InSAR) technology, with its advantages of extensive coverage in surface deformation monitoring and all-weather traceability of the injection processes, has become one of the promising technologies frequently adopted in worldwide CCS projects. However, there is no mature evaluation system to determine whether InSAR technology is suitable for each CO2 sequestration area. In this study, a new evaluation model is proposed based on the eight factors that are selected from the principle of the InSAR technique and the unique characteristics of the CO2 sequestration area. According to the proposed model, the feasibility of InSAR monitoring is... [more]

This paper presents a comprehensive analysis of zero-voltage-switching (ZVS) realization with an improved charge-based method by considering both voltage dependency parasitic capacitance and dead time in dual-active-bridge (DAB) converters, when the voltage ratio between the primary and secondary sides does not match the turn ratio of the transformer. For this purpose, a unified equivalent circuit is proposed to represent the switching motions at all possible switching instances under the condition of one-leg manipulation. The combinations of switching cases can be presented in a table to build the corresponding equivalent circuit for ZVS analysis. Combined with the improved charge-based method, the common solutions of the minimum required switching current and the appropriate dead-time range for each equivalent circuit to realize ZVS are deduced. The allowable range of the dead time for ZVS as a function of the switching current is analyzed to determine the appropriate dead time. Once... [more]

When tubing is in a high-temperature and high-pressure environment, it will be affected by the impact of non-constant fluid and other dynamic loads, which will easily cause the tubing to vibrate or even resonate, affecting the integrity of the wellbore and safe production. In the structural modal analysis of the tubing, the coupling effect of the fluid and the tubing needs to be considered at the same time. In this paper, a single tubing is taken as an example to simulate and analyze the modal changes of the tubing under dry mode and wet mode respectively, and the effects of fluid solid coupling effect, inlet pressure, and ambient temperature on the modal of the tubing are discussed. After considering the fluid−structure interaction effect, the natural frequency of tubing decreases, but the displacement is slightly larger. The greater the pressure in the tubing, the greater the equivalent stress on the tubing body, so the natural frequency is lower. Furthermore, after considering the f... [more]

Variable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into AC with an inverter circuit. The power quality concerns of both conversion stages are tackled by selecting high switching frequency PWM control and harmonics mitigation filters. Also, using a bulky DC-link capacitor is one of the big sources of low system reliability, so this approach increases the conversion losses, circuit, and control complications. The frequency step-down conversion is very attractive with direct AC-AC converters as it has a simple control and circuit structure, but these converters face poor power quality challenges once the output frequency is decreased with respect to an input. In these converters, the total harmonic distortion (THD) of the output voltage becomes very po... [more]

The household, industrial, and service sectors in Poland and the Baltic States have been facing ever-higher bills for their electricity consumption at a time when a number of them have been hit hard financially by the pandemic. Rising inflation, the border crisis—with its set of restrictions, or the spread of the fourth wave of the COVID-19 coronavirus pandemic, is causing strong concerns in the social and economic sphere, with significant increases in electricity prices. Many countries are implementing measures to reduce the adverse effects of rising electricity prices in response to this complex situation. The main orientation is towards obtaining energy from renewable sources, such as the sun. The current situation in the energy market determines the price per 1 KW. Among the countries under study, the price of electricity has increased the most in Poland. On the other hand, the development of the photovoltaic segment in Poland is undergoing a strong, upward trend. The above inspire... [more]

A novel three-dimensional elliptical-shaped Fresnel lens (ESFL) analytical model is presented to evaluate and maximize the solar energy concentration of Fresnel-lens-based solar concentrators. AutoCAD, Zemax and Ansys software were used for the ESFL design, performance evaluation and temperature calculation, respectively. Contrary to the previous modeling processes, based on the edge-ray principle with an acceptance half-angle of ±0.27° as the key defining parameter, the present model uses, instead, a Gaussian distribution to define the solar source in Zemax. The results were validated through the numerical analysis of published experimental data from a flat Fresnel lens. An in-depth study of the influence of several ESFL factors, such as focal length, arch height and aspect ratio, on its output performance is carried out. Moreover, the evaluation of the ESFL output performance as a function of the number/size of the grooves is also analyzed. Compared to the typical 1−16 grooves per mi... [more]

Currently, due to its various applications, the high-performance isolated dc-dc converter is in demand. In applications where unidirectional power transfer is required, the single active bridge (SAB) is the most suitable one due to its simplicity and ease of control. The general schematic of the SAB converter consists of an active bridge and a passive bridge, which are connected through a high-frequency transformer thus isolated. The paper summarizes the behavior of this converter in its three operation modes, namely the continuous, discontinuous, and boundary modes. Later, the features of this converter, such as its input-to-output and external characteristics are discussed. Input-to-output characteristics include the variation of converter output power, voltage, and current with an input control variable i.e., phase-shift angle, whereas the external characteristic is the variation of the output voltage as a function of output current. In this discussion, the behavior of this converte... [more]

The use of electric vehicles (EVs) to provide different grid services is becoming possible due to the increased penetration levels, mileage efficiencies, and useable battery sizes of EVs. One such application is providing reliability-as-a-service (RaaS) during short-term power outages. Instead of using a dedicated backup power source, EVs can be contracted to provide RaaS, which is an environmentally friendly solution with benefits for both building owners and EV owners. However, the presence of EVs at a particular location during different hours of the day and the availability of energy from EVs is uncertain. Therefore, in this study, a suitability analysis is performed concerning the use of EVs to provide RaaS for different types of buildings. First, the National Household Travel Survey (NHTS) survey data are used to estimate driver behavior, such as arrival/departure times, daily mileage, and traveling duration. Then, the usable battery size and mileage efficiency of EVs is extracte... [more]

The paper presents the conceptual assumptions of research concerning the design of a theoretical multi-criteria model of a system architecture to stabilize the operation of power distribution networks based on a hydrogen energy buffer, taking into account the utility application of hydrogen. The basis of the research process was a systematic literature review using the technique of in-depth analysis of full-text articles and expert consultations. The structural model concept was described in two dimensions in which the identified variables were embedded. The first dimension includes the supply chain phases: procurement and production with warehousing and distribution. The second dimension takes into account a comprehensive and interdisciplinary approach and includes the following factors: technical, economic−logistical, locational, and formal−legal.