Renewable energy sources are intended to support the decarbonisation process of the Polish economy. Since 2005, the share of renewable energy in total electricity in Poland has been increasing. The number of photovoltaic panels installed by prosumers as part of micro-installations increased particularly strongly. The aim of this research is an assessment of the impact of government programmes on the development of RES micro-installations in Poland. A regression discontinuity design was used in the analysis. It is a model from the group of average impact effect models used in evaluation studies. The added value of the presented study is its application in the assessment of the impact of implemented programmes on the number and output of micro-installations in Poland. In the study, it is shown that there had been no increase in the number and output of micro-installations at the adopted threshold (2019Q4). On the other hand, there was a sharp increase in them over the whole period starti... [more]

There is a growing interest in solar energy systems with storage battery assistance. There is a corresponding growing interest in hybrid converters. This paper provides a comprehensive review of hybrid converter topologies. The concept of a hybrid inverter is introduced and then classified into isolated and non-isolated structures based on using a galvanic transformer. The classification and description of each type are presented based on the features and applications. Furthermore, the most popular commercial solutions are investigated in terms of their simplicity, flexibility, efficiency, and battery technology. The summarizing features are presented through tables, and future trends for researchers to follow to develop efficient hybrid converters are discussed. This review paper is intended as a convenient reference for hybrid converter users.

High-concentration biodiesel-diesel fuel blends are an alternative fuel widely used for compression ignition engines. However, commercial diesel engines are not designed and set up for high-concentration biodiesel-diesel fuel blends. Hence, the aim of this research was to investigate the nonthermal plasma (NTP) activities during an NOx reduction and the soot characteristics on an unmodified diesel engine (Euro V) that is fueled with various biodiesel blends with diesel under a low exhaust gas temperature (<250 °C). The experiment found that the soot composition of biodiesel fuel produces lower levels of soot when compared with diesel, in terms of both number and mass. In addition, the activation energies (Ea) of carbon oxidation under an oxygen atmosphere were found to be approximately 154.57−173.64 kJ/mol.

The aim of the study was to identify the state of residential buildings in terms of energy consumption and modernisation in Poland against the background of the EU, and to determine factors and activities increasing households′ interest in net-zero energy buildings. In the European Union, we are observing a tendency to increase the energy efficiency of buildings, including residential, and decarbonise building stock by 2050. The objective of the undertaken activities is to reduce energy use and the negative impacts of the use of buildings on the environment. Attaining this objective requires modernising many buildings. This dissertation includes an investigation into the condition of buildings in Poland from the aspect of energy use and the kind of carriers of this energy, and also into another issue: what factors and activities may increase society′s interest in net-zero energy buildings, and in the use of energy from renewable sources in residential buildings. The studies were conduc... [more]

To realize the coordinated distribution of power in the multi-source system, maintain the charging balance among energy storage units, and improve the anti-interference capability of the bus voltage, a cascade control for an isolated PV-battery DC microgrid is proposed in this paper. First, to provide inertia for the microgrid so that it can cope with external disturbance, the parameters of the droop curve were adjusted by correlating the bus voltage variation rate, which improved the conventional droop control. Secondly, a nonsingular terminal sliding mode control was proposed to track voltage and current references and, thus, enhance the robustness of the DC microgrid. Moreover, the high-frequency chattering of the sliding mode control was inhibited with the exponential reaching law, and the Lyapunov function was utilized to verify the stability of the proposed nonsingular terminal sliding mode control method. Both the simulated and experimental results verified the correctness and e... [more]

Every wind turbine is subject to fluctuations in power generation, depending on climatic conditions. When electricity supply exceeds demand, wind turbines are forced to implement curtailment, causing a reduction in generation efficiency and commercial loss to turbine owners. Since the frequency and amount of curtailment of wind turbines increases as the amount of renewable energy become higher on Jeju Island in South Korea, Jeju is configuring a Power to Gas (P2G) water-electrolysis system that will be connected to an existing wind farm to use the “wasted energy”. In this study, economic analysis was performed by calculating the production cost of green hydrogen, and sensitivity analysis evaluated the variance in hydrogen cost, depending on several influential factors. Approaches to lower hydrogen costs are necessary for the following reasons. The operating company needs a periodical update of hydrogen sale prices by reflecting a change in the system margin price (SMP) with the highest... [more]

A deep understanding of the dissociation and transportation mechanism of natural gas hydrate (NGH), taking into account the effects of geo-stress, contributes to optimizing the development strategy and increases the exploitation efficiency of NGH. In this paper, the mathematical model, coupled with fluid heat and mass transfer, multiphase flow mechanics, and reaction kinetics with phase change in the process of hydrate decomposition was established. An axisymmetric two-dimensional model was developed to simulate the depressurization decomposition process of natural gas hydrate in the Berea sandstones. FLUENT software was used to solve the fundamental governing equations of the multi-phase flow, and UDF programming was employed to program the hydrate decomposition model and the modified permeability model in the dissociation and transportation of NGH. The simulation results were then validated by Masuda’s experimental data. The effects of gas saturation, outlet pressure, temperature, ab... [more]

In the context of the need to significantly reduce greenhouse gas emissions from personal transportation, a new process for the production of e-methanol is presented. It is a CO2 hydrogenation process, powered mainly by renewable energy sources such as photovoltaic electricity, with direct capture of carbon dioxide from the ambient air. With the main objective of estimating the feasibility and the impact of such a large-scale plant, the various components are evaluated in terms of masses and quantities necessary for an annual fuel production of 500,000 tons. The main reactor is analyzed to assess the required quantities of hydrogen and CO2. The production of hydrogen from the electrolysis of water is estimated, as well as the electrical power required and supplied by a large photovoltaic plant. The size of a realistic plant and its footprint are estimated. In addition, the mass of seawater to be desalinized and split in the electrolyser is calculated. The CO2 capture system is evaluate... [more]

The uncertainty of high penetration of renewable energy brings challenges to the safe and stable operation of a power system; the virtual synchronous compensation (VSCOM) can shift the demand and compensate real-time discrepancy between generation and demand, and can improve the active support ability for the power system. This paper proposes a novel capacity allocation strategy using VSCOM for renewable energy stations based on fuzzy constraints. Firstly, the basic framework of the VSCOM is constructed with energy storage and reactive power generator (SVG) unit. Secondly, the inertia and standby capacity requirements of high penetration of renewable energy system are modeled; on this basis, a capacity allocation model of each sub unit of the VSCOM is developed, and the investment economy and stable support needs are considered. Thirdly, the uncertainty set of wind power output is defined based on the historical data to find a decision that minimizes the worst-case expected where the w... [more]

The worldwide development of clean and low-carbon energy is undoubtedly imperative in the coming decades [...]

The optimum penetration of distributed generations into the distribution grid provides several technical and economic benefits. However, the computational time required to solve the constrained optimization problems increases with the increasing network scale and may be too long for online implementations. This paper presents a parallel solution of a multi-objective distributed generation (DG) allocation and sizing problem to handle a large number of computations. The aim is to find the optimum number of processors in addition to energy loss and DG cost minimization. The proposed formulation is applied to a 33-bus test system, and the results are compared with themselves and with the base case operating conditions using the optimal values and three popular multi-objective optimization metrics. The results show that comparable solutions with high-efficiency values can be obtained up to a certain number of processors.

Wind energy harvesting for electricity generation has a significant role in overcoming the challenges involved with climate change and the energy resource implications involved with population growth and political unrest. Indeed, there has been significant growth in wind energy capacity worldwide with turbine capacity growing significantly over the last two decades. This confidence is echoed in the wind power market and global wind energy statistics. However, wind energy capture and utilisation has always been challenging. Appreciation of the wind as a resource makes for difficulties in modelling and the sensitivities of how the wind resource maps to energy production results in an energy harvesting opportunity. An opportunity that is dependent on different system parameters, namely the wind as a resource, technology and system synergies in realizing an optimal wind energy harvest. This paper presents a thorough review of the state of the art concerning the realization of optimal wind... [more]

The Clean Forest project aims to valorize forest biomass wastes (and then prevent their occurrence as a fuel source in forests), converting it to bioenergy, such as the production of 2nd generation synthetic biofuels, like bio-methanol, bio-DME, and biogas, depending on the process operating conditions. Valorization of potential forest waste biomass thus enhances the reduction of the probability of occurrence of forest fires and, therefore, presents a major value for local rural communities. The proposed process is easy to implement, and energetically, it shows significantly reduced costs than the conventional process of gasification. Additionally, the input of energy necessary to promote electrolysis can be achieved with solar energy, using photovoltaic panels. This paper refers to the actual progress of the project, as well as the further steps which consist of a set of measures aimed at the minimization of the occurrence of forest fires by the valorization of forest wastes into ener... [more]

Although previous related studies illustrate several factors that reduce and eliminate ecological pollution, empirical evidence that examines the impact of banking development on footprint ecological quality is missed. This study explores the impact of banking development, renewable energy consumption, and economic growth on the ecological footprint of 27 OECD countries spanning data from 1990 to 2018. Using the method of moments quantile regression (MMQR), the results indicated that a 1% increase in banking expansion is projected to augment the ecological footprint in the OECD nations across all quantiles (first to ninth). Thus, the results affirm that banking development dampens ecological sustainability in the OECD nations. In contrast, the results indicate that renewable energy promotes ecological sustainability in the OECD nations across all quantiles (first to ninth). The empirical findings suggest that OECD policymakers should regard banking and economic development as a “green... [more]

The energy crisis that emerged as a result of the reduction in gas supplies from Russia is very topical and very important. This crisis affects not only Europe but also other world economies. As a result of Russia’s attack on Ukraine and the sanctions imposed on Russia, there was a drastic drop in Russian gas supplies, which triggered an increase in fuel prices and an energy crisis. In order to reduce the risk of insufficient gas supplies, European countries have decided to reuse coal and fossil fuels. This is the opposite direction to decarbonization and a zero-carbon economy. The undertaken research is unique, because the issue of slowing down the direction of decarbonization and returning to fossil fuels has not yet been extensively studied. Therefore, the analysis and research results are new in this area. The European project of green energy production from renewable energy sources that has been implemented so far, which aims to accelerate the implementation of a zero-emission eco... [more]

Francis turbines are most widely used in hydropower due to their characteristics which include a fast response and wide time-scale operation. The vortex rope inside Francis turbines is a common flow phenomenon, which always causes strong vibration, pressure pulsations, fatigue load, and even serious failure of the components. Vortex suppression methods can effectively change the velocity and pressure distribution of the flow field in the draft tube, reduce the volume of vortex rope and the amplitude of pressure pulsation, inhibit the development of cavitation erosion, and improve the operation stability of the hydro turbine. However, the vortex suppression method is not suitable for all working conditions, and the vortex suppression effect is also different. There are still many problems with how to analyze the vortex suppression effect and practicability of the turbine from multi-dimensions. It is of great significance to analyze the vortex suppression techniques and their practicabil... [more]

To reveal the effect of torrefaction pretreatment on pyrolysis and gasification reactivity of biomass, corn cob was first subjected to torrefaction pretreatment in a fixed-bed reactor at various reaction temperatures. The pyrolysis reactivity, kinetics, and gasification reactivity of torrefied corn cob were systematically assessed by various methods, proving that torrefaction pretreatment has a substantial influence on the physicochemical properties of corn cobs. The O/C and H/C molar ratios of corn cobs considerably drop with the increasing torrefaction temperature, and their higher heat-ing value (HHV) and energy density rise as well. It is found that torrefaction improves the pyrolysis reactivity of corn cobs because hemicellulose degradation is more severe than cellulose degradation during torrefaction, resulting in an increase in the percentage of cellulose in torrefied corn cobs. However, the severe depolymerization, polycondensation, and carbonization reaction during torre-facti... [more]

Energy provided by microgrids should be considered, especially because their purpose is to supply loads from the available power source of the combined sources of energy, including the grid, optimally and efficiently to satisfy the load demand securely and economically. Sensing the accuracy of the different physical parameters of the combined power sources and energy storage plays a crucial part in the efficiency and resilience of microgrids. The present microgrids mostly use conventional sensors, which are greatly impacted by ambient conditions such as high-voltage (HV) and electromagnetic interference (EMI). So, this paper presents an enhanced microgrid based on replacing the conventional sensors with fiber Bragg grating (FBG) sensors renowned for their immunity to EMI and HV, in addition to the virtue of distributing sensing capability. The enhanced microgrid based on FBG sensing was tested experimentally at different potential points predefined on the microgrid and validated with a... [more]

The main objective of this study is to establish analytical feasibility for the deployment of solar panels in Qatar houses and other organisations; to calculate, by the use of analytical means, solar panel deployment scenarios with different panel sizes, efficiency, and sun per day, in order to estimate generated energy and compare that with actual consumption over a period of twelve months. In addition, the study aims to provide a comparative indicator on the ratio of generated energy to consumed energy and consumed electrical energy (GtoC), to establish the possibility of using the GtoC ratio as a new renewable energy rating index, for use in renewable energy investment and sales forecasting, in maintaining comparisons between different installation scenarios, and in upgrade planning and decision making. This study’s analytical solutions might be correlated with data from in situ solar panel installation scenarios in order to fully establish the performance under operational scenario... [more]

Renewable energy consumption is one of the most important factors in meeting the goal of “30 and 60” in China. However, the maintenance of the transmission section affects the amount of generation transfer, further affecting the consumption of renewable energy. Hence, in this study, a time-series renewable energy production simulation (REPS) is proposed in order to accurately predict the power generation in a simulated situation. According to the results of the REPS, the sensitivity of the different sections’ maintenance can be calculated and determined. The appropriate maintenance strategies can be selected for different situations by comparing the consumption rate; as an example, we conducted a case study. The results show that the quota in the transmission section has higher sensitivity; a larger quota indicates a greater sensitivity to the consumption rate. The results also show that a larger quota is more suitable for maintenance in February or November, since the consumption rate... [more]

The electrification of the transportation sector contributes to a cleaner environment in non-interconnected island (NII) systems or standalone islands. Moreover, e-mobility can significantly contribute to achieving very high renewable energy source (RES) penetration levels in islands, allowing a reduction both in the emissions due to the conventional generation and the system’s cost. Ιncreased RES penetration, however, can pose technical challenges for an island’s system. In order to overcome these challenges, new technologies like grid-forming converters are important. Moreover, the provision of new ancillary services in relation to battery storage systems might be considered, while novel control and protection schemes are needed to ensure secure operation. E-mobility can also contribute to solving technical problems that arise from very high RES penetration by providing frequency containment reserves or reactive power compensation. Since EV charging demand introduces modifications in... [more]

Liquid fuel has been the main source of energy in internal combustion engines (ICE) for decades. However, lithium-ion batteries (LIB) have replaced ICE for environmentally friendly vehicles and reducing fossil fuel dependence. This paper focuses on the comparative analysis of battery thermal management system (BTMS) to maintain a working temperature in the range 15−35 °C and prevent thermal runaway and high temperature gradient, consequently increasing LIB lifecycle and performance. The proposed approach is to use biodiesel as the engine feed and coolant. A 3S2P LIB module is simulated using Ansys-Fluent CFD software tool. Four selective dielectric biodiesels are used as coolants, namely palm, karanja, jatropha, and mahua oils. In comparison to the conventional coolants in BTMS, mainly air and 3M Novec, biodiesel fuels have been proven as coolants to maintain LIB temperature within the optimum working range. For instance, the use of palm biodiesel can lightweight the BTMS by 43%, compa... [more]

A gravity-type heat pipe boiling characteristics test rig was constructed to solve the heat dissipation problem of fuel cells during operation. The boiling heat transfer characteristics of water in a parallel plate under negative pressure at different inclination angles and heat flow density input are investigated. The results show that: First, the gravity-type heat pipe can dissipate some heat and it is possible to use it for fuel cell heat dissipation. Second, with a certain range of heat flow density, the temperature of all parts of the plate is about 80 °C, with a small temperature difference, which is conducive to the safe operation of the fuel cell. Third, the heat flow density is in the range of 2222~3111 W·m−2, the temperature difference is large, and the outlet temperature is greater than 80 °C, which exceeds the operating temperature of the fuel cell, and the power-type heat pipe should be used for heat dissipation. Fourth, the average temperature of the plate placed at an in... [more]

Rooftop solar photovoltaic (PV) systems could significantly contribute to renewable energy production and reduce domestic energy costs. In Italy, as in other countries, the current incentives generate a modest annual increase after the generous fiscal incentives that kick-started the PV market in the 2008−2013 period. Several factors are, however, at play that can speed up the installation process, such as the improvements in PV technology at declining prices, the increased availability of battery-storage (BS) systems, the growing use of electric appliances, the uptake of electric cars, and the increased environmental awareness. We integrate two research methodologies, discrete choice modeling and agent-based modeling, to understand how these factors will influence households’ decisions regarding PV and BS installations and how agents interact in their socioeconomic environment. We predict that in Italy, given the preference structure of homeowners, the continuing decline in costs, and... [more]

Renewable energy resources such as offshore wind and wave energy are environmentally friendly and omnipresent. A hybrid offshore wind-wave energy system produces a more sustainable form of energy that is not only eco-friendly but also economical and efficient as compared to use of individual resources. The objective of this paper is to give a detailed review of co-generation technologies for hybrid offshore wind and wave energy. The proposed area of this review paper is based on the power conversions techniques, response coupling, control schemes for co-generation and complimentary generation, and colocation and integrated conversion systems. This paper aims to offer a systematic review to cover recent research and development of novel hybrid offshore wind-wave energy (HOWWE) systems. The current hybrid wind-wave energy structures lack efficiency due to their design and AC-DC-AC power conversion that need to be improved by applying an advanced control strategy. Thus, using different po... [more]