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Due to growing consciousness regarding the environmental impact of fossil-based and non-sustainable materials in construction and building applications, there have been an increasing interest in bio-based and degradable materials in this industry. Due to their excellent chemical and thermo-physical properties for thermal energy storage, bio-based phase change materials (BPCMs) have started to attract attention worldwide for low to medium temperature applications. The ready availability, renewability, and low carbon footprint of BPCMs make them suitable for a large spectrum of applications. Up to now, most of the BPCMs have been incorporated into inorganic matrices with only a few attempts to set the BPCMs into bio-matrices. The current paper is the first comprehensive review on BPCMs incorporation in wood and wood-based materials, as renewable and sustainable materials in buildings, to enhance the thermal mass in the environmentally-friendly buildings. In the paper, the aspects of choosing BPCMs, bio-based matrices, phase change mechanisms and their combination, interpretation of life cycle analyses, and the eventual challenges of using these materials are presented and discussed.

Hydraulic fracturing has made the production of gas more economical. Shale gas possesses the potential to arise as a main natural gas source worldwide. It has been assessed that the top 42 countries, including the U.S., are predicted to own 7299 trillion cubic feet (tcf) of technically recoverable shale gas resources. The main goal of this paper is to serve as a guide of different shale gas extraction methods. The significance of these methods and possible pros and cons are determined. Each technique was explained with the support of literature review. Specifically, this paper revealed that some fracking methods such as pulsed arc electrohydraulic discharges (PAED), plasma stimulation and fracturing technology (PSF), thermal (cryogenic) fracturing, enhanced bacterial methanogenesis, and heating of rock mass are at the concept stage for conventional and other unconventional resources. Thus, these found to be significant for stimulating natural gas wells, which provides very good production results. This paper also discovered that fracking remains the recommended technique used by the oil and gas industries.

This paper presents a study on the impact of adjacent markets on the electricity market, realizing the advantages of acting in several different markets. The increased use of renewable primary sources to generate electricity and new usages of electricity such as electric mobility are contributing to a better and more rational way of living. The investment in renewable technologies for the distributed generation has been creating new opportunities for owners of such technologies. Besides the selling of electricity and related services (ancillary services) in energy markets, players can participate and negotiate in other markets, such as the carbon/CO2 market, the guarantees of origin market, or provide district heating services selling of steam and hot water among others. These market mechanisms are related to the energy market, originating a wide market strategy improving the benefits of using distributed generators. This paper describes several adjacent markets and how do they complement the electricity market. The paper also shows how the simulation of electricity and adjacent markets can be performed, using an electricity market simulator, and demonstrates, based on market simulations using real data from the Iberian market, that the participation in various complementary markets can enable power producers to obtain extra profits that are essential to cover the production costs and facilities maintenance. The findings of this paper enhance the advantages for investment on energy production based renewable sources and more efficient technologies of energy conversion, This work was supported by national funds through FCT, Fundação para a Ciência e a Tecnologia, under projects UIDB/50021/2020, UIDB/00760/2020 and CEECIND/01811/2017. This work has also received funding from the EU Horizon 2020 research and innovation program under project DOMINOES (grant agreement No 771066).

Thin-film photovoltaic technology has begun to be applied in building-integrated photovoltaics (BIPVs), and it is believed that thin-film photovoltaic technology has potential in building-integrated photovoltaic applications. In this paper, a hybrid approach was investigated which combined the maximum power point tracking (MPPT) algorithm of three-stage variable step size with continuous conduction mode (CCM)/discontinuous current mode (DCM). The research contents of this paper include the principle analysis of the maximum power point tracking algorithm, the design of the sampling period, and the design of a double closed-loop control system and correction factor. A system model was built in MATLAB/Simulink, and a comparative simulation was carried out to compare the performance of the proposed method with some traditional methods. The simulation results show that the proposed approach has the ability to fast-track and make the system run stably. Furthermore, it can make the system respond quickly to environmental changes. An experimental platform was built, and the experimental results validated and confirmed the advantages of the proposed method.

Building energy renovations can effectively improve the environmental performance and energy sustainability of existing buildings. From 2007 onwards, the Chinese government has promoted energy-saving renovations of existing urban residential buildings. Nevertheless, various quality failures happen during the construction period in energy-saving renovation projects of residential buildings. Yet, the causes and their characters remain largely unknown. Through a literature review, this paper investigates the causes of quality failures. Validated through experts&rsquo, interviews, a total of 18 causes were identified in building energy renovation projects. These causes were analyzed from two main aspects: the importance of a cause (related to impact and frequency), and the level of effort required to address a cause (related to origin and scale), using both a questionnaire survey and a focus group. The results indicate that the critical causes of quality failures are working under high-cost and high-time pressure, adverse natural conditions, fraud of construction companies, incomplete construction site survey, poor checking procedures of supervisors, poor operational skilled workers, inadequate equipment performance, lack of experienced project managers, and incomplete building information in projects. The causes were classified as external and internal causes of building energy renovation projects. The outcome of this paper should aid policy makers and project coordinators to focus on critical causes of quality failures, and to develop effective actions and policy interventions to achieve successful renovation projects with high-quality performance.

This paper optimizes opening positions on building facades to maximize the natural ventilation’s potential for ventilation and cooling purposes. The paper demonstrates how to apply computational fluid dynamics (CFD) simulation results to architectural design processes, and how the CFD-driven decisions impact ventilation and cooling: (1) background: A CFD helps predict the natural ventilation’s potential, the integration of CFD results into design decision-making has not been actively practiced; (2) methods: Pressure data on building facades were obtained from CFD simulations and mapped into the 3D modeling environment, which were then used to identify optimal positions of two openings of a zone. The effect of the selected opening positions was validated with building energy simulations; (3) results: The cross-comparison study of different window positions based on different geographical locations quantified the impact on natural ventilation effectiveness; and (4) conclusions: The optimized window position was shown to be effective, and some optimal solutions contradicted the typical cross-ventilation strategy.

The paper presents the assessment of the resources of methane considered as the main mineral in the most prospective selected areas of the Upper Silesian Coal Basin, Poland in the region of undeveloped deposits. The methane resources were estimated by means of a volumetric method at three depth levels, 1000, 1250, and 1500 m. A part of the Studzienice deposit comprising three coal seams, 333, 336, and 337, located in a methane zone was chosen for the numerical modeling of simulated methane production. The presented static 3D model has been developed using Petrel Schlumberger software. The total resources of methane in the area amount to approximately 446.5 million of Nm3. Numerical simulations of methane production from the selected coal seams with hydraulic fracturing were conducted by means of Schlumberger ECLIPSE reservoir simulator. Based on the simulations, it was concluded that, in the first six months of the simulations, water is produced from the seams, which is connected with the decrease in the rock mass pressure. The process prompts methane desorption from the coal matrix, which in turn results in a total methane production of 76.2 million of Nm3 within the five-year period of the simulations, which constitutes about 17% of total methane resources (GIP). The paper also presents a detailed analysis of Polish legislation concerning the activities aimed at prospecting, exploring, and extracting the deposits of hydrocarbons.

Considering the fact that electric vehicle battery charging based on the current charging station is time-consuming, the charging technology needs to improve in order to increase charging speed, which could reduce range anxiety and benefit the user experience of electric vehicle (EV). For this reason, a 1 MW battery charging station is presented in this paper to eliminate the drawbacks of utilizing the normal 480 VAC as the system input to supply the 1 MW power, such as the low power density caused by the large volume of the 60 Hz transformer and the low efficiency caused by the high current. The proposed system utilizes the grid input of single-phase 8 kVAC and is capable of charging two electric vehicles with 500 kW each, at the same time. Therefore, this paper details how high-voltage SiC power modules are the key enabler technology, as well as the selection of a resonant-type input-series, output-parallel circuitry candidate to secure high power density and efficiency, while intelligently dealing with the transient processes, e.g., pre-charging process and power balancing among modules, and considering the impact on the grid, are both of importance.

The agricultural sector can play an important role in the transformation of the energy economy in Poland. Special attention in this paper has been paid to the development of the agricultural biogas market in Poland. The considerations mainly concern organizational and economic aspects. Agricultural biogas plant represents the circular cycle of matter and energy. It enables the establishment of low-carbon, resource-efficient links between the agriculture and energy sectors. This is an important element of the circular economy, where waste from agricultural production and the agri-food industry, coming from renewable resources, is transformed into goods with a higher added value. The social and economic needs of the present generation and future generations are considered. The paper presented the characteristics of the Polish market, i.e., the number of entities, the number and location of plants, as well as the production volumes. Analyses were performed in the area of raw materials used to produce agricultural biogas. The analyses were carried out between 2011 and 2018. According to analyses, the potential of the agricultural biogas market in Poland is currently being used to a small extent. It is necessary not only to provide institutional support but also to increase the awareness of farmers and managers in agri-food companies of the possibility of using production waste for energy purposes.

The wind turbine drivetrain suffers significant impact loads that severely affect the reliability and safety of wind turbines. Bearings and gears within the drivetrain are critical components with high repair costs and lengthy downtime. To realistically assess the system reliability, we propose to establish an electromechanical coupling dynamic model of the wind turbine considering the control strategy and environmental parameters and evaluate the system’s reliability of wind turbine drivetrain based on loads of gears and bearings. This paper focuses on the dynamic reliability analysis of the wind turbine under the control strategy and environmental conditions. SIMPACK (v9.7, Dassault Systèmes, Gilching, Germany) is used to develop the aero-hydro-servo-elastic coupling dynamic model with the full drivetrain that considers the flexibility of the tower and blade, the stochastic loads of wind and waves, gear meshing features, as well as the control strategy. The system reliability level of wind turbine drivetrain at different wind conditions is assessed using survival signature and fault tree analysis (FTA), and the influences of strength degradation of the transmission components on the system reliability are explored. Following this, the bending fatigue reliability and contact fatigue reliability concerning different wind conditions are compared in this paper. A case study is performed to demonstrate the effectiveness and feasibility of the proposed methodology.

To present great environmental pressure from energy consumption during textile production, this paper calculates the energy footprint (EFP) of Shaoxing’s textile industry, from 2005 to 2018. Moreover, this study analyzes the relationship between Shaoxing’s textile industry energy consumption and economic development by using decoupling theory. Furthermore, the Logarithmic Mean Divisia Index decomposition method was employed to investigate the main factors that affect the EFP of Shaoxing’s textile industry. Research results show the following: (1) The growth rate of the total output value of Shaoxing’s textile industry was greater than the growth rate of the EFP, from 2005 to 2007. Thus, the decoupling state showed a weak decoupling, and EFP intensity decreased. (2) The EFP and economic growth were mainly based on the strong decoupling of Shaoxing’s textile industry from 2008 to 2015 (except for 2011), and EFP intensity declined further. (3) Economic recession in the textile industry was severe in Shaoxing, from 2016 to 2018, and the EFP also showed a downward trend. The state of decoupling appeared as a recessive decoupling (2016) and a weak negative decoupling (2017 and 2018), and EFP intensity first increased and then decreased. (4) The total effect of the factors affecting the EFP of the textile industry in Shaoxing demonstrated a pulling trend, and industrial scale played a significant role in driving the EFP. The energy consumption intensity effect contributed the largest restraint. This paper fills in the gaps in the environmental regulation means and methods of pillar industrial clusters in specific regions.

Analyzing data from the Energy Poverty Observatory in Europe, it emerges that more than 50 million households in the EU live in energy poverty (people that cannot heat their homes during winter; cannot make their homes comfortable during the summer; pay their energy bills late). Research studies realized in the last 20 years highlight that making energy demand efficient and effective is the more significant and socially important the more it is able to involve users who are unable to sustain energy demand. The evolution of the research sees a narrowing of the field of investigation by focusing on the user dimension of energy poverty, stressing the role of citizens not only as consumer but also as producers of solutions to tackle energy poverty, real energy communities of agents. The paper aims to provide a systematic literature review highlighting the major findings of the topic, investigating the relationship between spatial and social issues, and looking at the state of energy poverty by addressing the profiling of users and consequently of services useful to overcome their current vulnerable condition. The paper is structured in two core sections. The first one gives the results of a systematic literature review on the energy/fuel poverty topic, the second one deepens the role of communities and individuals need, crucial in defining new design approaches for supportive solutions to tackle energy poverty.

The paper assesses the impact of combustion of biofuels produced based on municipal sewage sludge in stoker-fired boilers on the amount of pollutant emissions and examines the tendency of ash deposition of biofuels formed during the combustion process. The combustion tests were performed in a laboratory system enabling simulation of a combustion process present in stoker-fired boilers. The study was conducted for three types of biofuels; i.e., fuel from sewage sludge and coal slime (PBS fuel), sewage sludge and meat and bone meal (PBM fuel) and fuel based on sewage sludge and sawdust (PBT) with particle size of 35 mm and 15 mm. This paper describes and compares the combustion process of biofuels with different granulation and composition and presents the results of changes in emission values of NOx, SO2, CO, and CO2. The emission results were compared with the corresponding results obtained during combustion of hard coal. The results showed that biofuels with lower particle sizes were ignited faster and the shortest ignition time is achieved for fuel based on sewage sludge and coal slime‐PBS fuel. Also, the highest NO and SO2 emissions were obtained for PBS fuel. During the combustion of fuel based on sewage sludge and meat and bone meal (PBM), on the other hand, the highest CO2 emissions were observed for both granulations. Biofuels from sludge show a combustion process that is different compared to the one for hard coal. The problems of ash fouling, slagging, and deposition during biofuels combustion were also identified. The tendency for ash slagging and fouling is observed, especially for fuel from sewage sludge and meat and bone meal (PBM) and fuel based on sewage sludge and sawdust (PBT) ashes which consist of meat and bone meal and sawdust which is typical for biomass combustion.

With the gradual increasing of the transmission voltage level, the situation of interference on secondary side equipment in smart substations is becoming more serious. The authors tested the interference waveforms caused by the circuit breaker’s operation at the smart substation, which showed the severity of the electromagnetic (EM) environment. This paper takes the electronic current transformer acquisition card as an example. The influence of EM interference sources on the reliability of the acquisition card is analyzed. Then, standardized electromagnetic compatibility (EMC) immunity tests of the international electrotechnical commission (IEC) for different interferences are implemented. Typical output characteristics of acquisition cards for different tests are analyzed. Innovatively, this paper proposes a quantitative evaluation method of output waveform disturbance to evaluate the acquisition card’s performance. This disturbance distortion is of great significance to the EM environment estimation of the acquisition card.

Considering the huge power consumption, rapid response and the short-term heat reserving capacity of the air conditioning load in the building&rsquo, s energy system, the air conditioning load and its system can be equivalent to the virtual energy storage device for the power grid. Therefore, to obtain a high matching building renewable energy system, a virtual energy storage system of the air conditioning load, accompanied by a storage battery, was built in the paper. Then, operating strategies for the virtual energy storage of the air conditioning load and storage battery were designed. Further, to quantize the contribution of the virtual energy storage to the improvement of matching characteristics, two indicators of the demand side and supply side in the energy system were adopted, including on-site energy fraction (OEFr) and on-site energy matching (OEMr). Lastly, matching characteristic research of the building&rsquo, s renewable energy system based on virtual energy storage of the air conditioning load was established and analyzed by TRNSYS and MATLAB in Tianjin, China. The results revealed that a better matching characteristic performance of the building&rsquo, s renewable energy systems driven by virtual energy storage was obtained. In the condition set out in the paper, compared with that without virtual energy storage, the average values of OEFr and OEMr after virtual energy storage were 0.66 and 0.77, which increased by 8.19% and 8.45% respectively. Simultaneously, the battery operation performance in the building renewable system was improved when the virtual energy storage was working. The times of charge and discharge cycles decreased after virtual energy storage, and the depth of discharge of the battery reduced by 23.37% on a specific day.

Subhourly modeling of power systems and the use of the stochastic optimization are two relevant solutions proposed in the literature to address the integration of stochastic renewable energy sources. With this aim, this paper deals with the effect of different formulations of the subhourly stochastic unit commitment (SUC) problem on power system dynamics. Different SUC models are presented and embedded into time domain simulations (TDS) through a cosimulation platform. The objective of the paper is to study the combined impact of different frequency control/machine parameters and different SUC formulations on the long-term dynamic behaviour of power systems. The analysis is based on extensive Monte Carlo TDS (MC-TDS) and a variety of scenarios based on the New England 39-bus system.

This paper presents a SWOT analysis of the impact of recent EU regulatory changes on the business case for energy storage (ES) using the UK as a case study. ES technologies (such as batteries) are key enablers for increasing the share of renewable energy generation and hence decarbonising the electricity system. As such, recent regulatory changes seek to improve the business case for ES technologies on national networks. These changes include removing double network charging for ES, defining and classifying ES in relevant legislations, and clarifying ES ownership along with facilitating its grid access. However, most of the current regulations treat storage in a similar way to bulk generators without paying attention to the different sizes and types of ES. As a result, storage with higher capacity receives significantly higher payment in the capacity market and can be exempt from paying renewable energy promotion taxes. Despite the recent regulatory changes, ES is defined as a generation device, which is a barrier to a wide range of revenue streams from demand side services. Also, regulators avoid disrupting the current energy market structure by creating an independent asset class for ES. Instead, they are encouraging changes that co-exist with the current market and regulatory structure. Therefore, although some of the reviewed market and regulatory changes for ES in this paper are positive, it can be concluded that these changes are not likely to allow a level playing field for ES that encourage its increase on energy networks.

This paper addresses economic aspects of heat savings in the context of strategic heat planning. The analysis uses the city of Aalborg, Denmark, as a case where municipalisation through a recent acquisition of a coal-fired cogeneration of heat and power (CHP) plant has made an update of a municipal strategic energy plan necessary. Combining datasets on buildings and insulation techniques with economic methods, we investigate how the local district heating tariff can be adapted to improve the conditions for heat savings and support the transition to lower supply temperatures in line with the requirements of future fourth generation district heating systems. The paper concludes that implementing a fully variable heat tariff scheme improves the financial incentive for heat savings, while also making the system development less vulnerable to fluctuations and shortages in capital markets. The paper supplements existing literature on heat savings with novelty in its approach and in its systematic investigation of the interplay between tariff policies and interest rates. This paper addresses economic aspects of heat savings in the context of strategic heat planning. The analysis uses the city of Aalborg, Denmark, as a case where municipalisation through a recent acquisition of a coal-fired cogeneration of heat and power (CHP) plant has made an update of a municipal strategic energy plan necessary. Combining datasets on buildings and insulation techniques with economic methods, we investigate how the local district heating tariff can be adapted to improve the conditions for heat savings and support the transition to lower supply temperatures in line with the requirements of future fourth generation district heating systems. The paper concludes that implementing a fully variable heat tariff scheme improves the financial incentive for heat savings, while also making the system development less vulnerable to fluctuations and shortages in capital markets. The paper supplements existing literature on heat savings with novelty in its approach and in its systematic investigation of the interplay between tariff policies and interest rates.

Nowadays, the usage of thermal insulation materials is widespread not only in the building sector but also in the vehicle industry. The application of fibrous or loose-fill insulation materials like glass wool or mineral wool as well as aerogel is well known. Aerogel-based materials are among the best solid materials for thermal insulation available today; they are prepared through a sol−gel process. For building walls, the glass-fiber-enhanced types are the frequently used ones. They are prepared by adding the liquid−solid solution to the fibrous batting, which is called a sol−gel process. In the present paper, the changes in the most important building physical properties of aerogel blankets after thermal annealing are presented. The samples were subjected to isochronal heat treatments from 70 to 210 °C for 24 h. The changes in the thermal conductivity were followed by Holometrix Lambda heat flow meter, and differential scanning calorimetry results were also recorded. From the measured values, together with the densities, the most important thermal properties were calculated, such as thermal resistance, diffusivity, effusivity (heat absorption), and thermal inertia. In this paper, we attempt to clarify the role played by thermal annealing in the transient thermal properties of aerogel materials. Besides presenting the measurement results, a theoretical background is given. The investigations of not only the steady-state but also the transient thermal parameters of the materials are momentous at the design stage.

This paper presents the results of research describing the thermokinetics of brown coal&rsquo, s (lignite) drying process in a fountain-bubble fluidized bed dryer. The drying medium was atmospheric air of a variable temperature in subsequent tests, which ranged from 27 to 70 &deg, C. This paper presents the results of many experimental studies for two different types of brown coal: xylite, from the Bełchat&oacute, w mine, and earth, from the Tur&oacute, w mine. The two types of brown coal are used to assess different sized coal particles and different air drying temperatures. The functions parameterizing the moisture content of dried coal at different air drying temperatures at any given time are also presented.

This paper evaluates the potential for automated lighting control as a resource for frequency regulation of the electric grid system in the context of current energy policies, economic incentives, and technological trends. The growing prevalence of renewable energy has increased the need for ancillary services to maintain grid frequency and stability. While demand side resources like heating, ventilating, and air-conditioning systems, as well as water treatment plants are already evaluated as regulation service providers, the potential application to electrical lighting systems has largely been ignored. Yet, aggregations of lighting systems that are retrofitted with intelligent controls could conceivably contribute to frequency regulation services with little impact on user comfort. To further explore the feasibility of lighting potential, this paper explores (1) how lighting control systems are limited by visual comfort perception and acceptability, (2) how such limitations impact the performance of the lighting system as an frequency regulation resource, and (3) how the market potential of lighting systems as demand side resources compares in different regional transmission organizations. Finally, the impact of developing technologies on the application of lighting systems for frequency regulation is discussed.

This paper reports the application of RC dynamic models (network of resistances and capacitances analogous to electrical networks) to obtain the heat loss coefficient (HLC) from a dynamic test campaign carried out in an in-use building. It is a well-insulated building located in Gainsborough, U.K. This case study and data were made available to participants in the IEA–EBC Annex 71 project Building Energy Performance Assessment Based on In-Situ Measurements. The analysis reported in this paper is mainly focused on the identification of the main heat transfer contributions and also on the translation of these phenomena to the RC models used to obtain the required HLC. First pre-processing and qualitative analysis were carried out. Afterwards several candidate models were constructed according to different plausible assumptions and approximations. The validity of the results obtained using these models has been evaluated taking into account the agreement among different data series and also the levels of the residuals obtained using the different models. The work concludes obtaining accurate estimates of the HLC from the energy balance including the following relevant contributions: space heating, solar gains, internal gains due to appliances, and internal gains due to metabolic activity. These terms were modelled using the following driving variables: consumption of gas and water, electricity production by the photovoltaic (PV) panels and electricity consumption (modelling internal gains due to appliances and occupancy patterns).

The development of the renewable energy industry is a priority of economic policies in many countries, since it is viewed as one of the key growth sectors in the economy, playing also a very important role in mitigating climate change. At the international level, renewable energy is an issue of international cooperation but also an area of high trade tensions between countries. The main goal of this paper is to examine the nature and sources of recent trade disputes in the solar photovoltaic sector, which is the most dynamically growing sector in the green energy industry. In particular, the paper explores the links between the contemporary trade disputes and modern protectionism and between protectionist policies and practices and the export competitiveness in the growing sector of the economy. To achieve the aim of the study we explore in detail the WTO trade disputes over photovoltaic (PV) products, which occurred in the years 2007–2018. The products covered by the analysis were solar modules and cells classified under the HS code 854140. In our research we also used measures of descriptive statistics, hierarchical cluster analysis and revealed comparative advantage indexes. Our key results demonstrate the existence of links between protectionist policy causing trade conflicts and the export competitiveness. The research has also allowed us to identify problems of future studies concerning the association between trade protectionism and global value chains in the solar energy sector.

The paper presents a research study on modeling and computer simulation of injecting CO2 into the coal seams of the Upper Silesian Coal Basin, Poland connected with enhanced coal bed methane (ECBM) recovery. In the initial stage of the research activities, a structural parameter model was developed specifically with reference to the coal-bearing formations of the Upper Carboniferous for which basic parameters of coal quality and the distribution of methane content were estimated. In addition, a lithological model of the overall reservoir structure was developed and the reservoir parameters of the storage site were analyzed. In the next stage of the research, the static model was supplemented with detailed reservoir parameters as well as the thermodynamic properties of fluids and complex gases. The paper discusses a series of simulations of an enhanced coalbed methane recovery process with a simultaneous injection of carbon dioxide. The analyses were performed using the ECLIPSE software designed for simulating coal seam processes. The results of the simulations demonstrated that the total volume of CO2 injected to a designated seam in a coal mine during the period of one year equaled 1,954,213 sm3. The total amount of water obtained from the production wells during the whole period of the simulations (6.5 years) was 9867 sm3. At the same time, 15,558,906 sm3 of gas was recovered, out of which 14,445,424 sm3 was methane. The remaining 7% of the extracted gas was carbon dioxide as a result of reverse production of the previously injected CO2. However, taking into consideration the phenomena of coal matrix shrinking and swelling, the total amount of injected CO2 decreased to approximately 625,000 sm3.

The increasing resort to renewable energy distributed generation, which is needed to mitigate anthropogenic CO2 emissions, leads to challenges concerning the proper operation of electric distribution systems. As a result of the intrinsic nature of Renewable Energy Sources (RESs), this generation shows a high volatility and a low predictability that make the balancing of energy production and consumption difficult. At the same time, the electrification of new energy-intensive sectors (such as heating) is expected. This complex scenario paves the way for new sources of flexibility that will have more and more relevance in the coming years. This paper analyses how the electrification of the heating system, combined with an electric flexibility utilisation module, can be used to mitigate the problems related to the fluctuating production of RES. By using Power-to-Heat (P2H) technologies, buildings are able to store the overproduction of RES in the form of thermal energy for end-use according to the principle of the so-called Virtual Energy Storage (VES). A context-aware demand flexibility extraction based on the VES model and the flexibility upscale and utilisation on district-level through grid simulation and energy flow optimisation is presented in the paper. The involved modules have been developed within the PLANET (PLAnning and operational tools for optimising energy flows and synergies between energy NETworks) H2020 European project and interact under a unified co-simulation framework with the PLANET Decision Support System (DSS) for the analysis of multi-energy scenarios. DSS has been used to simulate a realistic future energy scenario, according to which the imbalance problems triggered by RES overproduction are mitigated with the optimal exploitation of the demand flexibility enabled by VES.

Background: This paper proposes a Nautilus isometric spiral vertical axis wind turbine, which is a new structure, and its aerodynamic performance and power generation performance need to be analyzed. Methods: A 3D model of the wind turbine was built and its aerodynamic performance was analyzed. Then the wind turbine power generation and grid-connected simulation platform was built by MATLAB/SIMULINK, and its power generation performance and subsequent grid connection were studied. Results: The basic parameters of the wind turbine were obtained. In order to improve efficiency, parameters such as pressure, torque, wind energy utilization rate and relative velocity of wind turbines with different blade numbers and different sizes were compared. In addition, by building a simulation platform for the power generation control system, the power generation characteristics and grid connection characteristic curves of the generator were obtained. Conclusions: When the number of blades is three and the ratio between the ellipse major axis and minor axis of the blade inlet is 0.76, the best efficiency of the wind turbine can be obtained. Application of the power generation control system used in this paper can achieve grid-connected operation of this wind turbine. It also confirmed that the Nautilus isometric spiral wind turbine has good performance and is worthy of in-depth research.

This paper proposes detailed and practical guidance on applying model-based design (MBD) for voltage and frequency stability assessments, control tuning and verification of off-grid hybrid power plants (HPPs) comprising both grid-forming and grid-feeding inverter units and synchronous generation. First, the requirement specifications are defined by means of system, functional and model requirements. Secondly, a modular approach for state-space modelling of the distributed energy resources (DERs) is presented. Flexible merging of subsystems by properly defining input and output vectors is highlighted to describe the dynamics of the HPP during various operating states. Eigenvalue (EV) and participation factor (PF) analyses demonstrate the necessity of assessing small-signal stability over a wide range of operational scenarios. A sensitivity analysis shows the impact of relevant system parameters on critical EVs and enables one to finally design and tune the central HPP controller (HPPC). The rapid control prototyping and control verification stages are accomplished by means of discrete-time domain models being used in both off-line simulation studies and real-time hardware-in-the-loop (RT-HIL) testing. The outcome of this paper is targeted at off-grid HPP operators seeking to achieve a proof-of-concept on stable voltage and frequency regulation. Nonetheless, the overall methodology is applicable to on-grid HPPs, too.

To reduce the dependence on oil and environmental pollution, the development of electric vehicles has been accelerated in many countries. The implementation of EVs, especially battery electric vehicles, is considered a solution to the energy crisis and environmental issues. This paper provides a comprehensive review of the technical development of EVs and emerging technologies for their future application. Key technologies regarding batteries, charging technology, electric motors and control, and charging infrastructure of EVs are summarized. This paper also highlights the technical challenges and emerging technologies for the improvement of efficiency, reliability, and safety of EVs in the coming stages as another contribution.

The co-evolution of techno-economic, societal, environmental and political-institutional systems towards sustainable energy transitions is largely influencing the disruptive reconfiguration of the energy sector across the globe. At the heart of this disruption is the peer-to-peer energy sharing concept. Nonetheless, peer-to-peer energy sharing business models are yet very little put into practice due to the rigid energy market structures and lagging regulatory frameworks across the globe. In view of this, this paper presents a novel peer-to-peer energy sharing business model developed specifically for the context of the Portuguese energy market, which was successfully trialed in three pilot projects in Portugal under real market conditions. All things considered, the novelty of this paper lies on an innovative approach for the collaborative use of the surplus electricity generation from photovoltaic systems between end-users under the same low voltage/medium voltage transformer substation, which resulted in direct financial benefits to them. While absent deregulation obstructs the implementation of effective peer-to-peer energy sharing markets in Portugal, such demonstration projects are essential to challenge restrictive regulatory frameworks that do not keep pace with techno-economic and societal innovations, thus helping to build the emerging consumer-centric energy regime and disrupt the old one.

Green loans are a way of financing green innovation. Two important factors, the lending interest rate and the loaning scale, should be focused on. In this paper, we explore the impact of lending interest rates and loaning scale on green innovation. We show that the incentive of green innovation strongly depends on the lending interest rate and the loaning scale through model analysis. Moreover, the dependence is summarized as a two-step strategy. In the first step, the lending interest rate should be lower than some rate thresholds given in the paper. Otherwise, green innovation fails to be stimulated. In the second step, if the lending interest rate is lower than the given rate threshold, then the practical loaning scale should lie between two thresholds of loaning scale derived in the paper, such that the green innovation will be stimulated. What is more, to guarantee the green effect of the innovation on the environment, we construct a threshold of loaning scale. If the loaning scale is larger than this threshold, then the innovation will show green effect on the environment. Otherwise, green innovation loses its environmental significance. The government stimulates green innovation through government subsidy. In this paper, we consider three kinds of government subsidy, including a subsidy for the bank, subsidy for the enterprise before and after implementing green innovation. Some appropriate government subsidy scales are presented.

To promote the utilization of distributed resources, this paper proposes a concept of a micro energy system (MES) and its core structure with energy production, conversion, and storage devices. In addition, the effect of demand&ndash, response on the operation of a MES is studied. Firstly, based on uncertainties of a MES, a probability distribution model is introduced. Secondly, with the objectives of maximizing operating revenue, and minimizing operational risk and carbon emissions, a multi-objective coordinated dispatching optimization model was constructed. To solve this model, this paper linearizes objective functions and constraints via fuzzy satisfaction theory, then establishes the input&ndash, output matrix of the model and calculates the optimal weight coefficients of different objective functions via the rough set method. Next, a comprehensive dispatching optimization model was built. Finally, data from a MES in Longgang commercial park, Shenzhen City, were introduced for a case study, and the results show that: (1) A MES can integrate different types of energy, such as wind, photovoltaics, and gas. A multi-energy cycle is achieved via energy conversion and storage devices, and different energy demands are satisfied. Demand&ndash, response from users in a MES achieves the optimization of source&ndash, load interaction. (2) The proposed model gives consideration to the multi-objectives of operating revenue, operational risk, and carbon emissions, and its optimal strategy is obtained by using the proposed solution algorithm. (3) Sensitivity analysis results showed that risks can be avoided, to varying degrees, via reasonable setting of confidence. Price-based demand&ndash, response and maximum total emission allowances can be used as indirect factors to influence the energy supply structure of a MES. In summary, the proposed model and solution algorithm are effective tools for different decision makers to conceive of dispatching strategies for different interests.

In the entrained flow coal gasification process, the gas production is critically affected by the operating temperature (OT) and coal ash melting point (AMP), and the AMP is one of key factors for the determinations of OT. Considering the fact that coal is a typical nonhomogeneous substance and the coal ash composition varies from batch to batch, this paper proposes the application of the Markov Chain (MC) method in simulation of the random AMP series and the stochastic optimization of OT based on MC simulation for entrained flow coal gasification. The purpose of this paper is to provide a more accurate optimal OT decision method for entrained flow coal gasification practice. In this paper, the AMP was regarded as a random variable, and the random process method, Markov Chain, was used to describe the random AMP series of feed coal. Firstly, the MC simulation model about AMP was founded according to an actual sample data, 200 sets of AMP data from an industrial gasification plant under three simulation schemes (the sample data were individually divided into 16, eight and four state groups,). The comparisons between the simulation results and the actual values show that the founded MC simulation model descries the AMP series very well. Then, a stochastic programming model based on MC simulation for OT optimization was developed. Finally, this stochastic programming optimization model was optimized by genetic algorithm (GA). Comparing with the conventional OT optimization method, the proposed stochastic OT optimization model integrated MC simulation can ascertain a more accurate OT for guiding the coal gasification practice.

Climate change and global warming are significantly affected by carbon emissions that arise from the burning of fossil fuels, specifically coal, oil, and gas. Accurate prices are essential for the purposes of measuring, capturing, storing, and trading in carbon emissions at regional, national, and international levels, especially as carbon emissions can be taxed appropriately when the price is known and widely accepted. This paper uses a novel Capital (K), Labor (L), Energy (E) and Materials (M) (or KLEM) production function approach to calculate the latent carbon emission prices, where carbon emission is the output and capital (K), labor (L), energy (E) (or electricity), and materials (M) are the inputs for the production process. The variables K, L, and M are essentially fixed on a daily or monthly basis, whereas E can be changed more frequently, such as daily or monthly, so that changes in carbon emissions depend on changes in E. If prices are assumed to depend on the average cost pricing, the prices of carbon emissions and energy may be approximated by an energy production model with a constant factor of proportionality, so that carbon emission prices are a function of energy prices. Using this novel modeling approach, this paper estimates the carbon emission prices for Japan using seasonally adjusted and unadjusted monthly data on the volumes of carbon emissions and energy, as well as energy prices, from December 2008 to April 2018. The econometric models show that, as sources of electricity, the logarithms of coal and oil, though not Liquefied Natural Gas (LNG,) are statistically significant in explaining the logarithm of carbon emissions, with oil being more significant than coal. The models generally displayed a high power in predicting the latent prices of carbon emissions. The usefulness of the empirical findings suggest that the methodology can also be applied for other countries where carbon emission prices are latent.

Power grid investment behavior (PGIB) is a necessary prerequisite to ensure safe and reliable power supply. The supervision of PGIB is an important measure to reduce electricity price. It helps to release the dividends of the new power system reform and promote the sustainable development of the power industry. However, for a long time, China&rsquo, s regulation of PGIB was relatively weak, lacking clear supervision awareness and effective supervision methods. On the basis of clarifying the contents of PGIB supervision, this paper establishes an evaluation index system for the compliance of PGIB from the government supervision perspective, involving four dimensions and 14 secondary indicators. Furthermore, a hybrid evaluation model based on the combined decision-making trial and evaluation laboratory method (DEMATEL-ANP), analytical network process method, and vague set is proposed. The results reveal that the control over cost and efficiency of the PGIB in China is not enough. According to the results, this paper puts forward the indicators that close attention should be paid to and the work priorities in China&rsquo, s supervision of PGIB, which has certain practical value for the implementation of new power system reform and the sustainable development of Chinese power industry.

The paper overviews the current energy demand trends in the building sector for the Arab region using reported historical energy consumption. Moreover, the paper describes the current energy efficiency policies and regulations for all the Arab countries specific to both residential and commercial buildings. Finally, the paper evaluates potential benefits for large-scale energy efficiency programs specific to new and existing building stocks within the Arab region using a bottom-up analysis approach. The analysis of the available energy consumption for all the Arab countries has shown that the Arab region presents a significant variation in energy consumption levels between its sub-regions and countries. Indeed, the Arab region includes oil-producing countries such as Saudi Arabia with the largest energy use per capita in the World with over 9000 kWh/person of electricity used annually in buildings. However, the same region has the least developed countries such as Sudan and Yemen with the lowest energy use per capita in the World with barely 100 kWh/person/year of electrical consumption. The review of the existing regulations has indicated that several Arab countries have not implemented any energy efficiency codes and standards for building envelope, lighting, heating and cooling equipment, and appliances. A cost-effectiveness analysis has indicated that the Arab region can incur significant benefits in upgrading the energy efficiency of its new and existing buildings especially its households. Specifically, the adoption and the enforcement of stringent energy efficiency codes for new residential and commercial buildings can result in a reduction of 12.7 TWh/year in final annual energy consumption for the Arab region. Moreover, retrofit programs targeting existing buildings can save up to 470 TWh or a third of the building sector final energy consumption per year after 2030. Combining comprehensive energy efficiency requirements for new buildings and extensive retrofit programs for existing buildings would reduce the total final energy consumption of the building sector in the Arab region by 600 TWh by 2030 and by 900 TWh by 2050 if all the energy programs start to be implemented by 2020.

This paper proposes an approach for accurate wind speed forecasting. While previous works have proposed approaches that have either underperformed in accuracy or were too computationally intensive, the work described in this paper was implemented using a computationally efficient model. This model provides wind speed nowcasting using a combination of perturbed observation ensemble networks and artificial neural networks. The model was validated and evaluated via simulation using data that were measured from wind masts. The simulation results show that the proposed model improved the normalized root mean square error by 20.9% compared to other contending approaches. In terms of prediction interval coverage probability, our proposed model shows a 17.8% improvement, all while using a smaller number of neural networks. Furthermore, the proposed model has an execution time that is one order of magnitude faster than other contenders.

The energy yield of a solar panel can be severely impacted by partial shading. Shade caused by nearby static objects can hardly be avoided in installations such as building-applied or building-integrated photovoltaics. Smart reconfigurable photovoltaics (PV) panels are able to change their intra-module configuration to reduce this impact: small substrings can be rewired to be connected in a more optimal configuration. To achieve this, a reconfiguration switch needs to be designed. In this paper a switch for the optimization of module power by reconfiguration of all strings (SOMBRA), a smart switch, is presented. SOMBRA is a fully integrated, low-ohmic switch, designed for currents up to 10 A. It is fully floating up to 50 V, while still being able to communicate with a central unit as an inter-integrated circuit (I 2 C) slave. Two versions were realized, SOMBRA-LV10 for low voltages (LV) and a load current of 10 A, and SOMBRA-HV05 for high voltages (HV) and a load current of 5 A. Measurements proved these devices to be functional, measuring an on-resistance of 1.3 m &Omega, for SOMBRA-LV10 and 7.3 m &Omega, for SOMBRA-HV05. This paper will elaborate on the operation, design, and implementation of SOMRBA, as well as the first tests with a small reconfigurable PV module.

Energy efficiency is one of the most relevant issues that the scientific community, and society in general, must face in the next years. Furthermore, higher energy efficiencies will contribute to worldwide sustainability. Buildings are responsible for 40% of the overall consumed energy. Smart Grids and Smart Buildings are playing an essential role in the definition of the next generation of sustainable Smart Cities. The main goal is reducing the impact of energy consumption on the environment as much as possible. This paper focuses on information communication technologies (ICTs) and techniques, their key characteristics and contribution to obtain higher energy efficiencies in smart buildings. Given that electrical energy is the most used, the investigation mainly centres on this energy. This paper also pays attention to green energies and energy harvesting due to their contribution to energy efficiency by providing additional clean energy. The main contribution of this investigation is pointing out the most relevant existing and emerging ICT technologies and techniques which can be used to optimize the energy efficiency of Smart Buildings. The research puts special attention on available, novel and emerging sensors, communication technologies and standards, intelligence techniques and algorithms, green energies and energy harvesting. All of them enable high-performance intelligent systems to optimize energy consumption and occupants’ comfort. Furthermore, it remarks on the most suitable technologies and techniques, their main features and their applications in Smart Buildings.

Reverse osmosis (RO) is a desalination technique that is commonly preferred because of its low energy consumption. In this paper, an innovative, thermally powered RO desalination process is presented. This new thermo-hydraulic process uses solar thermal energy in order to realize the pressurization of the saltwater beyond its osmotic pressure to allow its desalination. This pressurization is enabled thanks to a piston or a membrane set in motion in a reservoir by a working fluid that follows a thermodynamic cycle similar to an Organic Rankine Cycle. In this cycle, the evaporator is heated by low-grade heat, such as the one delivered by flat-plate solar collectors, while the condenser is cooled by the saltwater to be treated. Such an installation, designed for small-scale (1 to 10 m3·day−1) brackish water desalination, should enable an average daily production of 500 L of drinkable water per m² of solar collectors with a specific thermal energy consumption of about 6 kWhth·m−3. A dynamic modeling of the whole process has been developed in order to study its dynamic cyclic operating behavior under variable solar thermal power, to optimize its design, and to maximize its performances. This paper presents the preliminary performance results of such a solar-driven desalination process.

Increasing penetration of electric vehicles (EVs) gives rise to the challenges in the secure operation of power systems. The EV charging loads should be distributed among charging stations in a fair and incentive-compatible manner while ensuring that power transmission and transformation facilities are not overloaded. This paper first proposes a charging right (or charging power ration) trading mechanism and model based on blockchain. Considering all kinds of random factors of charging station loads, we use Monte Carlo modeling to determine the charging demand of charging stations in the future. Based on the charging demand of charging stations, a charging station needs to submit the charging demand for a future period. The blockchain first distributes initial charging right in a just manner and ensures the security of facilities. Given that the charging urgency and elasticity differences vary by charging stations, all charging stations then proceed with double auction and peer-to-peer (P2P) transaction of charging right. Bids and offers are cleared via double auctions if bids are higher than offers. The remaining bids and offers are cleared via the P2P market. Then, this paper designs the charging right allocation and trading platform and smart contract based on the Ethernet blockchain to ensure the safety of the distribution network (DN) and the transparency and efficiency of charging right trading. Simulation results based on the Ethereum private blockchain show the fairness and efficiency of the proposed mechanism and the effectiveness of the method and the mechanism.

In this paper, the concept of smart battery pack is introduced. The smart battery pack is based on wireless feedback from individual battery cells and is capable to be applied to electric vehicle applications. The proposed solution increases the usable capacity and prolongs the life cycle of the batteries by directly integrating the battery management system in the battery pack. The battery cells are connected through half-bridge chopper circuits, which allow either the insertion or the bypass of a single cell depending on the current states of charge. This consequently leads to the balancing of the whole pack during both the typical charging and discharging time of an electric vehicle and enables the fault-tolerant operation of the pack. A wireless feedback for implementing the balancing method is proposed. This solution reduces the need for cabling and simplifies the assembling of the battery pack, making also possible a direct off-board diagnosis. The paper validates the proposed smart battery pack and the wireless feedback through simulations and experimental results by adopting a battery cell emulator.

Buildings, energy, and the environment are key issues facing construction around the world. The energy efficiency of buildings is a key topic when it comes to reducing the world’s energy consumption, releasing harmful gases, and global climate change, as they consume about 40% of the world’s energy supplies. Heat losses in buildings reduce the energy performance of buildings and are basically important to them. In the paper, the authors focus on the main problems related to heat losses generated by chimney systems, which are inseparable equipment of building structures, resulting in lower energy efficiency and, at the same time, technical efficiency and durability of the building partitions themselves. Authors present thermal imaging with its contribution to the detection of heat losses, thermal bridges, insulation problems, and other performance disturbances, and then verifications using appropriate simulation models. The mathematical apparatus of artificial neural networks was implemented to predict the temperature distributions on the surfaces of prefabricated chimney solutions. In Europe, we can often find a large building substance equipped with traditional chimneys, which disrupts the current trend of striving to reduce energy consumption, especially that derived from fossil fuels. Speaking of energy-efficient buildings, one should not ignore those that, without additional security and modern installations, are constantly used in a very wide range. Therefore, the article deals with an essential problem that is not perceived in design studies and during the operation period as having a basis in incorrect architectural solutions and which can be easily eliminated. It concerns the cooling of internal partitions of buildings on their last storeys, in places where chimneys are located, regardless of their function. The authors of the paper decided to take a closer look at this phenomenon, which may allow the limiting of its effects and at the same time reduce its impact on the energy performance of technologically older buildings.

Nowadays, the increasing number of nonlinear loads and renewable energy resources pose new challenges for the standard electrical grid. Conventional solutions cannot handle most of them. The weakest component in the whole system is a conventional distribution (converting medium to low AC voltage) transformer. It should not operate with unbalanced, heavily distorted voltage and cannot control power flow or compensate current harmonics. One of the promising solutions to replace the conventional transformer and thus minimize power flow and grid distortions is a power electronics device called a solid state transformer (SST). Depending on the SST topology, it can have different functionalities, and, with the proper control algorithm, it is able to compensate any power imbalances in both low voltage (LV) and medium voltage (MV) grid sides. In the case of a three energy conversion stage SST, the LV and the MV stages can be treated separately. This paper focuses on the MV-AC to the MV-DC stage only based on a star-connected cascaded H-bridge converter. In this paper, a simple control solution for such a converter enabling different current control strategies to distribute power among the phases in an MV grid in the case of voltage imbalances is proposed. Simulation and experimental results proved good performance and verified the validity of the proposed control algorithm.

Since there are not standard configurations of the Concentrating Photovoltaic (CPV) systems, several types of optics are designed and analyzed. In this paper, the optical performances of a spherical mirror and a commonly used Fresnel lens of the same diameter are compared, highlighting their impact on the CPV system energy performance. First, the absolute and percentual variation trends of optical concentration factor and optical efficiency as function of the distance between each optical system and receiver are analyzed. The concentration levels obtained by means of the spherical mirror are much higher than the Fresnel lens, with maximum values of optical efficiency equal to 72.8% and 24.1%, respectively. The analysis of the concentration reduction due to a solar-tracking failure has also allowed the estimation of the acceptance angle, thus observing that the spherical mirror requires a less accurate solar tracker with respect to the Fresnel lens, especially if a secondary optics is adopted. As for the energy comparison, the spherical mirror allows increase of the Triple-Junction (TJ) cell temperature up to about 65 °C higher than the environmental temperature and to reach an electrical power of about 15 W in correspondence of a concentrated solar radiation of 470 kW/m2. Finally, the deviation between the cumulative electric energy produced by the TJ cell in the cases of correct and incorrect solar tracking and for the configurations with and without secondary optics has been also evaluated for both the optics. The equations experimentally obtained in this paper represent a more accurate tool to describe the physical phenomenon in comparison with the equations theoretically obtained for similar CPV systems. The results can be used to design a real CPV system that adopts a Fresnel lens or a spherical mirror. The equations experimentally obtained in this paper represent a more accurate tool to describe the physical phenomenon in comparison with the equations theoretically obtained for similar CPV systems. The results can be used to design a real CPV system that adopts a Fresnel lens or a spherical mirror.

Results-based financing (RBF) programmes in the clean cooking sector have gained increasing donor interest over the last decade. Although the risks and advantages of RBF have been discussed quite extensively for other sectors, especially health services, there is limited research-documented experience of its application to clean cooking. Due to the sheer scale of the important transition from ‘dirty’ to clean cooking for the 4 billion people who lack access, especially in the Global South, efficient and performance-proven solutions are urgently required. This paper, undertaken as part of the work of the UKAid-funded Modern Energy Cooking Services (MECS) programme, aims to close an important research gap by reviewing evidence-based support mechanisms and documenting essential experiences from previous and ongoing RBF programmes in the clean cooking and other sectors. On this basis, the paper derives key strategic implications and learning lessons for the global scaling of RBF programmes and finds that qualitative key performance indicators such as consumer acceptance as well as longer-term monitoring are critical long-term success factors for RBF to ensure the continued uptake and use of clean cooking solutions (CCS), however securing the inclusion of these indicators within programmes remains challenging. Finally, by discussing the opportunities for the evolution of RBF into broader impact funding programmes and the integration of energy access and clean cooking strategies through multi-sector approaches, the paper illustrates potential steps to enhance the impact of RBF in this sector in the future.

The present article analyzes the technological advancement and innovations related to drilling operations. It covers the review of currently proven and emerging technologies that could mitigate the drilling operational deficiencies and instabilities that could hinder operational performance activities and the economic part of drilling development with great effort to minimize their environmental footprint. Drilling system design and operations are among the major aspects and cost-effective endeavors of the oil and gas industries, which are therefore technology dependent. They are also considered to be among the most expensive operations in the world, as they require huge expenses daily. Drilling success, depending on prevalent conditions, is a function of several general factors. These include the selection of the best technologies and tools, procedural optimization, concrete problem-solving, accurate prediction, and rapid decision-making. Consequently, any sorts of tools or advanced technologies that can improve the time-efficient operational and economic performance of drilling activities are essential and demanded. The paper provides a review of available technologies and developmental innovations based on both company-based and academic research-enabled drilling solutions over the past 5 years in the field of drilling systems and technological design. The paper further highlighted potential technologies that could be tapped in from other industries and could possibly be adopted by pushing the conventional boundaries of drilling operations.

The underground coal gasification (UCG) represents an effective coal mining technology, where coal is transformed into syngas underground. Extracted syngas is cleaned and processed for energy production. Various gasification agents can be injected into an underground georeactor, e.g., air, technical oxygen, or water steam, to ensure necessary temperature and produce syngas with the highest possible calorific value. This paper presents an experimental study where dynamic optimization of operating variables maximizes syngas calorific value during gasification. Several experiments performed on an ex situ reactor show that the optimization algorithm increased syngas calorific value. Three operation variables, i.e., airflow, oxygen flow, and syngas exhaust, were continually optimized by an algorithm of gradient method. By optimizing the manipulation variables, the calorific value of the syngas was increased by 5 MJ/m3, both in gasification with air and additional oxygen. Furthermore, a higher average calorific value of 4.8–5.1 MJ/m3 was achieved using supplementary oxygen. The paper describes the proposed ex situ reactor, the mathematical background of the optimization task, and results obtained during optimal control of coal gasification.

This paper focuses on the analysis of trends in the development of nuclear energy in selected European and non-European countries in the context of the pace of renewable energy development in the world. The perception of Poles related to their openness to various energy sources against the background of European trends was also examined, as well as their ecological approach to the quality of the environment in this context. The survey was carried out using the Computer Assisted Web Interview (CAWI) technique. The total number of correctly completed forms was 923. To identify the ecological attitude, purchasing attitude, and the perception of nuclear energy, the research tool contained a number of statements on the issues studied, and the respondents assessed compliance with their opinion using a seven-point bipolar scale. The semantic differential was also used to gather opinions on the characteristics of nuclear energy. This paper shows that global trends are promoting the development of unstable renewable energy sources and the reduction of the share of nuclear power plants as an energy source. It has also been shown that the Organization for Economic Co-operation and Development (OECD) countries are more skeptical about nuclear power than countries that do not belong to the OECD (for example, China and Africa).

Infrared thermography has been used as a key means for the identification of overheating defects in power cable accessories. At present, analysis of thermal imaging pictures relies on human visual inspections, which is time-consuming and laborious and requires engineering expertise. In order to realize intelligent, autonomous recognition of infrared images taken from electrical equipment, previous studies reported preliminary work in preprocessing of infrared images and in the extraction of key feature parameters, which were then used to train neural networks. However, the key features required manual selection, and previous reports showed no practical implementations. In this contribution, an autonomous diagnosis method, which is based on the Faster RCNN network and the Mean-Shift algorithm, is proposed. Firstly, the Faster RCNN network is trained to implement the autonomous identification and positioning of the objects to be diagnosed in the infrared images. Then, the Mean-Shift algorithm is used for image segmentation to extract the area of overheating. Next, the parameters determining the temperature of the overheating parts of cable accessories are calculated, based on which the diagnosis are then made by following the relevant cable condition assessment criteria. Case studies are carried out in the paper, and results show that the cable accessories and their overheating regions can be located and assessed at different camera angles and under various background conditions via the autonomous processing and diagnosis methods proposed in the paper.

This paper investigates the potential of a new integrated solar concentrated photovoltaic (CPV) system that uses a solo point focus Fresnel lens for multiple multi-junction solar cells (MJSCs). The proposed system comprises of an FL concentrator as the primary optical element, a multi-leg homogeniser as the secondary optical element (SOE), a plano-concave lens, and four MJSCs. A three-dimensional model of this system was developed using the ray tracing method to predict the influence of aperture width, height, and position with respect to MJSCs of different reflective and refractive SOE on the overall optical efficiency of the system and the irradiance uniformity achieved on the MJSCs’ surfaces. The results show that the refractive homogeniser using N-BK7 glass can achieve higher optical efficiency (79%) compared to the reflective homogeniser (57.5%). In addition, the peak to average ratio of illumination at MJSCs for the reflective homogeniser ranges from 1.07 to 1.14, while for the refractive homogeniser, it ranges from 1.06 to 1.34, causing minimum effects on the electrical performance of the MJSCs. The novelty of this paper is the development of a high concentration CPV system that integrates multiple MJSCs with a uniform distribution of rays, unlike the conventional CPV systems that utilise a single concentrator onto a single MJSC. The optical efficiency of the CPV system was also examined using both the types of homogeniser (reflective and refractive).