High-temperature latent heat storage (LHS) systems using a high-temperature phase change medium (PCM) could be a potential solution for providing dispatchable energy from concentrated solar power (CSP) systems and for storing surplus energy from photovoltaic and wind power. In addition, ultra-high-temperature (>900 °C) latent heat storage (LHS) can provide significant energy storage density and can convert thermal energy to both heat and electric power efficiently. In this context, a 2D heat transfer analysis is performed to capture the thermo-fluidic behavior during melting and solidification of ultra-high-temperature silicon in rectangular domains for different aspect ratios (AR) and heat flux. Fixed domain effective heat capacity formulation has been deployed to numerically model the phase change process using the finite element method (FEM)-based COMSOL Multiphysics. The influence of orientation of geometry and heat flux magnitude on charging and discharge performance has been eval... [more]

The article presents experimental research focused on the improvement of solar cells efficiency using the photoluminescence down-shifting effect. In the paper, the authors present the results of solar cells performance enhanced with the proposed solution. As light energy converted active materials, rare earth elements of europium and dysprosium were implemented. In the experiments, luminescent layers were deposited on top of photovoltaic protective glass in order to absorb the highest possible amount of ultraviolet light from the incident solar spectrum. Spray coating deposition technology with various types of ink compositions was used for process optimization. It was observed that there are optimal concentrations and solvent types for the best conversion effect and consequently, the improvement of solar cell external quantum efficiency (EQE) together with the PV cell absolute efficiency enhancement.

Hydrogen mixed natural gas for combustion can improve combustion characteristics and reduce carbon emission, which has important engineering application value. A casing swirl burner model is adopted to numerically simulate and research the natural gas hydrogen mixing technology for combustion in gas boilers in this paper. Under the condition of conventional air atmosphere and constant air excess coefficient, the six working conditions for hydrogen mixing proportion into natural gas are designed to explore the combustion characteristics and the laws of pollution emissions. The temperature distributions, composition, and emission of combustion flue gas under various working conditions are analyzed and compared. Further investigation is also conducted for the variation laws of NOx and soot generation. The results show that when the boiler heating power is constant, hydrogen mixing will increase the combustion temperature, accelerate the combustion rate, reduce flue gas and CO2 emission, i... [more]

Intelligent integration of decentralised energy resources, local storage and direct consumption are key factors in achieving the transformation of the energy system. In this study, we present a modular simulation concept that allows the planning of decentralised energy systems for buildings and building blocks. In comparison to related studies, we use a simulation model for energy planning with a high time-resolution from the perspective of the energy system planner. In this study, we address the challenges of the grid connection in combination with an increasing number of electric vehicles (EV) in the future. The here developed model is applied for an innovative building block in Germany with a photovoltaic (PV) system, a combined heat and power (CHP) unit, battery storage and electric vehicles. The results of the simulation are validated with real-life data to illustrate the practical relevance and show that our simulation model is able to support the planning of decentralised energy... [more]

The research was a response to the search for alternative energy sources and the assessment of their profitability and legitimacy of use. The assessment used combined energy sources in the form of wind, solar, and natural gas energy. The research was carried out in various locations with varying degrees of sunlight and in various wind zones, which was motivated by the adopted strategy of increasing the importance of non-conventional energy sources and reducing greenhouse gas emissions. The evaluation was performed using the Homer Grid software. The studies showed the justification for the use of hybrid energy sources, combining renewable and non-renewable sources, at the current stage of development. In the conditions of the Lubuskie Voivodeship, the level of insolation was more important than the more favourable wind zone in such a model. Higher economic efficiency of the hybrid model was obtained in the southern location, with slightly less favourable conditions for wind installation... [more]

The deterioration of lithium-ion batteries has been detected by an increase in the battery impedance by means of an alternating current method or a battery capacity test. These methods require an interruption of the operation because the battery has to be removed. A method estimating equivalent circuit parameters of a lithium-ion battery during operation is proposed in this article. The increase in the internal impedance has a close relation to the deterioration of the battery. The circuit is expressed by a resister and an RC parallel circuit connected in series. The parameters can be estimated by applying a convolution technique to the voltage and current fluctuation of the battery during operation. A diagnosis circuit using a microcomputer is developed using a simple algorithm employing z-transformation in the parameter estimation. The estimated parameters depend on its state of charge (SOC) and ambient temperature. The SOC dependency is solved by estimating timing, and the temperatu... [more]

The transport sector powered by internal combustion engines (ICE) requires novel approaches to achieve near-zero CO2 emissions. In this direction, using CO2 capture and storage (CCS) systems onboard could be a good option. However, CO2 capture in mobile sources is currently challenging due to the operational and space requirements to install a CCS system onboard. This paper presents a systematic review of the CO2 capture in ICE driven transport to know the methods, techniques, and results of the different studies published so far. Subsequently, a case study of a CCS system working in an ICE is presented, where the energy and space needs are evaluated. The review reveals that the most suitable technique for CO2 capture is temperature swing adsorption (TSA). Moreover, the sorbents with better properties for this task are PPN-6-CH2-DETA and MOF-74-Mg. Finally, it shows that it is necessary to supply the energy demand of the CCS system and the option is to take advantage of the waste heat... [more]

In designing Archimedes screws, determination of the geometry is among the fundamental questions that may affect many aspects of the Archimedes screw powerplant. Most plants are run-of-river and highly depend on local flow duration curves that vary from river to river. An ability to rapidly produce realistic estimations for the initial design of a site-specific Archimedes screw plant helps to facilitate and accelerate the optimization of the powerplant design. An analytical method in the form of a single equation was developed to rapidly and easily estimate the Archimedes screw geometry for a specific site. This analytical equation was developed based on the accepted, proved or reported common designs characteristics of Archimedes screws. It was then evaluated by comparison of equation predictions to existing Archimedes screw hydropower plant installations. The evaluation results indicate a high correlation and reasonable relative difference. Use of the equation eliminates or simplifie... [more]

This paper proposes a method for improving hydrogen generation using pulse current in a proton exchange membrane-type electrolyzer (PEMEL). Traditional methods of electrolysis using direct current are known as the simplest approach to produce hydrogen. However, it is highly dependent on environmental variables, such as the temperature and catalyst used, to enhance the rate of electrolysis. Therefore, we propose electrolysis using a pulse current that can apply several dependent variables rather than environmental variables. The proposed method overcomes the difficulties in selecting the frequency of the pulse current by deriving factors affecting hydrogen generation while changing the concentration generated by the cell interface during the pulsed water-electrolysis process. The correlation between the electrolyzer load and the frequency characteristics was analyzed, and the limit value of the applicable frequency of the pulse current was derived through electrical modeling. In additio... [more]

Climate change is becoming a global problem. In many countries, actions are taken with the main aim of reducing CO2 emissions. The main action, especially in developed countries, is decarbonization. The European Union has become one of the organizations that plays a leading role in decarbonization of the economy. For this reason, renewable energy sources are being intensively developed in the EU countries. Solar energy with the use of PV installations is developing the fastest. Poland is one of the European leaders in photovoltaic development, and according to estimates for 2021−2025, it will continue to be. The aim of this study was to find out the opinions of people toward actions related to the decarbonization policy in Poland. These opinions were obtained through the prism of respondents’ attitudes toward energy produced by means of PV micro-installations. A questionnaire survey was used in this research. The survey was conducted using the CAWI (Computer-Assisted Web Interview) tec... [more]

In terms of energy generation and consumption, ships are autonomous and isolated power systems with energy requirements related to the type and kind of power demands and according to ship types: passenger ships, or commercial ships. Power supply on ships is traditionally based on engines thermal generators, which use fossil fuels, diesel, or natural gas. Due to the continuous operation of thermal generators in ships, this ends up increasing polluting gas emissions for the environment, mainly CO2. A combination of Renewable Energy Sources (RES) with traditional ship thermal engines can reduce CO2 emissions, resulting in a ‘greener’ interaction between ships and the environment. Due to the varying power needs for ship operation, considering the varying nature of load demands during long distance travels and during harbor entry, the use of RES must be evaluated. This paper presents a new control method to balance LNG ship load demands and power generation from RES, based on an accurate mo... [more]

This article contains a review of essential control techniques for maximum power point tracking (MPPT) to be applied in photovoltaic (PV) panel systems. These devices are distinguished by their capability to transform solar energy into electricity without emissions. Nevertheless, the efficiency can be enhanced provided that a suitable MPPT algorithm is well designed to obtain the maximum performance. From the analyzed MPPT algorithms, four different types were chosen for an experimental evaluation over a commercial PV system linked to a boost converter. As the reference that corresponds to the maximum power is depended on the irradiation and temperature, an artificial neural network (ANN) was used as a reference generator where a high accuracy was achieved based on real data. This was used as a tool for the implementation of sliding mode controller (SMC), fuzzy logic controller (FLC) and model predictive control (MPC). The outcomes allowed different conclusions where each controller ha... [more]

In some applications such as electric vehicles, electric motors should operate in a wide torque and speed ranges. An efficiency map is the contour plot of the maximum efficiency of an electric machine in torque-speed plane. It is used to provide an overview on the performance of an electric machine when operates in different operating points. The electric machine losses in different torque and speed operating points play a prominent role in the efficiency of the machines. In this paper, an overview about the change of various loss components in torque-speed envelope of the electric machines is rendered to show the role and significance of each loss component in a wide range of torque and speeds. The research gaps and future research subjects based on the conducted review are reported. The role and possibility of the utilization of the computational intelligence-based modeling of the losses in improvement of the loss estimation is discussed.

The automotive sector is rapidly accelerating its transformation towards electric mobility, and electric vehicle (EV) sales have been increasing year after year since the beginning of the decade [...]

All over the world, including Poland, authorities are taking steps to increase consumer interest in electric vehicles and sustainable transport as a way to reduce environmental pollution. For this reason, the electric vehicle market is dynamically and constantly developing, more and more modern vehicles are introduced to it, and purchases are often subsidized by the government. The aim of the article is to analyse the A−C segments of the Polish electric vehicle market and to recommend the most attractive vehicle from the perspective of sustainable transport. The aim of the research was achieved with the use of three multi-criteria decision aid (MCDA) methods, which deal well with the uncertainty and imprecision of data that occur in the case of many different parameters of electric vehicles. In particular, the following methods were used: the fuzzy technique for order of preference by similarity to ideal solution (TOPSIS), the fuzzy simple additive weighting (SAW) method, and the new e... [more]

The estimation of the social cost of climate change is typically carried out with complex, difficult to interpret, integrated assessment models (IAMs). Instead, this paper presents a simple, tractable model with which to estimate the willingness to pay of societies against climate change. The model is based on an already comprehensive and intuitive one developed by Besley and Dixit, which has been modified by including a backstop technology (e.g., a renewable energy technology). This improved formulation allows for a more realistic representation of the climate change problem in that it is able to include the decoupling of economic growth and GHG emissions. The model allows us to understand the implications of different assumptions, such as the rate of growth of the economy, or the damages expected from climate change, on the willingness to pay against it. Our results show that, for a baseline scenario, the willingness to pay (WTP) is 0.52% of annual GDP, lower than that obtained by Be... [more]

This article provides a comprehensive review of the state of the art and more recent developments of the thermochemical treatments of slurry fuels in fluidized beds (FB). The review focuses on FB combustion and gasification of slurry fuels based on coal, biomass, sludge, and wastes from industry, agriculture, and the civil sector. The investigations at research and industrial levels over the last decades are presented and discussed, highlighting the adopted technological solutions, the results in terms of feasibility and efficiency, and the perspectives of future development. The different behavior between bubbling and circulating beds was addressed, in particular the optimal choice depending on the process (combustion/gasification/pyrolysis) and fuel properties (e.g., water content). Fundamental studies on interactions between the slurry fuels and the hot bed materials are also reviewed. The cumulative trend of reviewed investigations over the last decades depicts the abandonment of c... [more]

The 2030 Climate target plan of the European Commission (EC) establishes a greenhouse gases (GHG) emissions reduction target of at least 55% by 2030, compared to 1990. It highlights that all transport modes—road, rail, aviation and waterborne—will have to contribute to this aim. A smart combination of vehicle/vessel/aircraft efficiency improvements, as well as fuel mix changes, are among the measures that can reduce GHG emissions, reducing at the same time noise pollution and improving air quality. This research provides a comprehensive analysis of recent research and innovation in low-emission alternative energy for transport (excluding hydrogen) in selected European Union (EU)-funded projects. It considers the latest developments in the field, identifying relevant researched technologies by fuel type and their development phase. The results show that liquefied natural gas (LNG) refueling stations, followed by biofuels for road transport and alternative aviation fuels, are among the r... [more]

Generally, the fault current supplied by inverter-based renewable energy sources (IBRES) and electrical storage systems (ESS) is about 1.2 to 2 times their rated current and much lower than synchronous generators because the former acts as a current source and the latter acts as a voltage source. A conventional power system in a small island is composed of only synchronous generators and protected from short circuit faults using an overcurrent relay (OCR). However, in the remote microgrid with IBRES, ESS, and synchronous generators, the fault current varies depending on the configuration of generation sources. Namely, the fixed OCR protection method cannot protect microgrids from short circuit faults. This paper proposes an adaptive protection method to protect the microgrid from faults by actively changing the OCR setting according to the state of the generator source combination. A microgrid with ESS and a synchronous generator is modeled and simulated through PSCAD/EMTDC software to... [more]

Climate and energy policies are tools used to steer the development of a sustainable economy supplied by equally sustainable energy systems. End-users should plan their investments accounting for future policies, such as incentives for system-oriented consumption, emission prices and hydrogen economy, to ensure long-term competitiveness. In this work, the utilization of variable renewable energy and flexibility potentials in a case study of an aggregate industry is investigated. An energy concept considering PV and battery expansion, flexible production, fuel cell electric trucks (FCEV) and hydrogen production is proposed, and analysed under expected techno-economic conditions and policies of 2030 using an energy system optimization model. Under this concept, total costs and emissions are reduced by 14% and 70%, respectively, compared to the business-as-usual system. The main benefit of PV investment is the lowered electricity procurement. Flexibility from schedulable manufacturing and... [more]

Decreasing the Pt loading and surface area of the cathode was found to accelerate the hydrogen evolution reaction in microbial electrolysis cells (MEC) at low substrate concentrations. The experimental wire cathode used in this study had a reduced Pt loading of 20 µg Pt/cm2 and only 14% of the surface area of the control disk-type cathode. With the wire cathodes, peak current densities of 33.1 ± 2.3 A/m2 to 30.4 ± 0.5 A/m2 were obtained at substrate concentrations of 0.4 g/L and 1.0 g/L, respectively, which were 5.4 to 6.2 times higher than those obtained with the disk electrode (5.1−5.7 A/m2). The higher cathode overpotentials and higher current densities obtained with the wire electrode compared to those observed with the disk electrode were advantageous for hydrogen recovery, energy recovery efficiencies, and the hydrogen volume produced (8.5 ± 1.2 mL at 0.4 g/L to 23.0 ± 2.2 mL at 1.0 g/L with the wire electrode; 6.8 ± 0.4 mL at 0.4 g/L to 21.8 ± 2.2 mL at 1.0 g/L with the disk ele... [more]

Battery energy storage systems (BESSs) are able to facilitate economical operation of the grid through demand response (DR), and are regarded as the most significant DR resource. Among them, distributed BESS integrating home photovoltaics (PV) have developed rapidly, and account for nearly 40% of newly installed capacity. However, the use scenarios and use efficiency of distributed BESS are far from sufficient to be able to utilize the potential loads and overcome uncertainties caused by disorderly operation. In this paper, the low-voltage transformer-powered area (LVTPA) is firstly defined, and then a DR grid edge controller was implemented based on deep reinforcement learning to maximize the total DR benefits and promote three-phase balance in the LVTPA. The proposed DR problem is formulated as a Markov decision process (MDP). In addition, the deep deterministic policy gradient (DDPG) algorithm is applied to train the controller in order to learn the optimal DR strategy. Additionally... [more]

Due to the high energy consumption of buildings, there is a demand for both economically and environmentally effective designs for building energy system retrofits. While multi-objective optimization can be used to solve complicated problems, its use is not yet widespread in the industry. This study first aims to develop an efficient and applicable multi-objective building energy system optimization method, used to dimension energy production and storage retrofit components in a case campus building in Lahti, Finland. Energy consumption data of the building are obtained with a dynamic energy model. The optimization model includes economic and environmental objectives, and the approach is found to function satisfactorily. Second, this study aims to assess the feasibility and issues of multi-objective single-building energy system optimization via the analysis of the case optimization results. The results suggest that economically beneficial local energy production and storage retrofits... [more]

The aim of the current paper is to present an approach to a wind turbine selection based on an annual wind measurements. The proposed approach led to a choice of an optimal device for the given wind conditions. The research was conducted for two potential wind farm locations, situated on the north of Poland. The wind measurements pointed out a suitability of the considered localizations for a wind farm development. Six types of wind turbines were investigated in each localization. The power of the wind turbines were in the range of 2.0 to 2.5 MW and with a medium size of the rotor being in the range of 82 to 100 m. The purpose of the research was to indicate a wind turbine with the lowest sensitivity to the variation of wind speed and simultaneously being most effective energetically. The Weibull density distribution was used in the analyses for three values of a shape coefficients k. The energy efficiency of the considered turbines were also assessed. In terms of the hourly distributi... [more]

The main objective of the research was to determine the long-term and short-term correlation between CO2 emissions per capita, energy consumption per capita, and the level of economic growth of GDP per capita in the V4 countries. These countries, being EU members since 2004 and previously being in the sphere of influence of the Soviet Union, have introduced a number of economic reforms, but in the area of climate protection, including decarbonization, they struggle with many problems, as their economies are largely dependent on energy from non-renewable resources. The results of the research are varied, but the authors confirmed, especially in the case of Poland, the long-term correlations between the studied variables. In the short term, such interdependencies also occurred, especially between the level of energy consumption per capita and the level of CO2 emissions.