The growing interest in processes that involve biomass conversion to renewable energy, such as anaerobic digestion, has stimulated research in this field in order to assess the optimum conditions for biogas production from abundant feedstocks, like agro-industrial wastes. Anaerobic digestion is an attractive process for the decomposition of organic wastes via a complex microbial consortium and subsequent conversion of metabolic intermediates to hydrogen and methane. The present study focused on the exploitation of liquid cow manure (LCM) and cheese whey (CW) as noneasily and easily biodegradable sources, respectively, using continuous stirred-tank reactors for biogas production, and a comparison was presented between single- and two-stage anaerobic digestion systems. No significant differences were found concerning LCM treatment, in a two-stage system compared to a single one, concluding that LCM can be treated by implementing a single-stage process, as a recalcitrant substrate, with t... [more]

The objective of this study was to investigate the factors that influence the consumer adoption of renewable energy in Thailand. The study adopted an extended theory of planned behavior (TPB) by including three additional variables. The study applied a quantitative study methodology, with primary data collected using a survey of consumers in five major cities in Thailand. The data were analyzed using structural equation modeling (SEM). The findings of the study indicated that perception of self-effectiveness, environmental concern, renewable energy awareness, and beliefs about renewable energy benefits have a significant and positive effect on consumers’ intention to adopt renewable energy. The cost of renewable was found to have a negative but non-significant influence on consumers’ adoption of renewable energy, while risk/trust perception was found to have a positive but non-significant influence on consumers’ adoption of renewable energy. The study concluded that stakeholders should... [more]

Construction time and time overruns for infrastructure projects have been frequently studied; however, the construction time of power plants has not been studied. This lack of study is problematic, as more renewable energy power plants, such as wind and solar, are planned for many jurisdictions. Accurately estimating the construction time of a power plant will assist construction planning, budget estimates, and policy development encouraging the use of more renewable sources. The construction times of utility scale power plants in Canada were studied using publicly available data. Multiple linear regression analysis techniques were applied to the data to generate construction time estimation functions for all power plants together, and for individual technologies. The analyses reveal that construction time is sensitive to jurisdiction and the decade of construction, indicating that decisions made by individual Canadian provincial governments at different times had statistically signifi... [more]

The Internet of Things (IoT) has found application in many components of implantable medical devices, wearable smart devices, monitoring systems, etc. The IoT devices are conventionally battery powered, even though, in several low power applications, they can also be powered using energy harvesting technology. Independently of the power sources (if batteries or environment), efficient and robust power converters must be designed to provide the small and distributed energy required by such IoT devices. This review paper will first provide an overview about the power consumption in IoT devices; second, it will discuss the most recent research and advance in the field of fully-integrated or embedded DC/DC converters, starting from high-performance integrated charge pumps or embedded inductive boost converters for specific harvesting sources (temperature, solar, and so on), to novel DC/DC converters for multiple energy sources.

Prior to full electric conversion, internal combustion engines will still maintain a paramount position in heavy goods and earth-moving vehicles. The most promising, cleaner alternative to fossil fuels is biodiesel. While it does not require alterations in the engine design, hence no major overhaul of existing infrastructure, biodiesel is more sustainable and clean-burning than petro-diesel. Extensive research has been reported on the effect of biodiesel blends, on the operational characteristics of compression ignition (CI) engines as well as the emissions behaviour of such engines. The performance characteristics of CI engines under transient operational conditions with Biodiesel blends has had limited attention so far from researchers. In the present work, transient performance characteristics of a CI engine has been evaluated for various biodiesel blends and its effects on performance behaviour have been quantified. In addition, emission footprints of CI engines under various trans... [more]

A theoretical−experimental annual analysis of a hybrid industrial direct−indirect solar air heating system performance for drying was conducted considering temperatures, useful energy Qu, efficiency η, and solar fraction SF. The direct solar air heating system located in Morelos, México, has flat-plate solar air collectors, and the indirect system has flat-plate solar water collectors, a thermal storage tank, a cross-flow fin, and a tube heat exchanger. A validated TRNSYS program modeled the process; the validation was carried out by comparing each component outlet temperature and useful energy with the respective experimental field data. The analysis considered annual usage over seven days a week, nine hours a day (from 09:00 to 18:00 h), and three operation modes. For the direct, indirect, and hybrid operation modes, the Qu values were 31.60, 55.19, and 75.18 MWh/yr; the annual η values were 0.44, 0.41, and 0.42; and the annual SF values were 0.45, and 0.73 for the indirect and hybri... [more]

Road transport is one of the key elements of economic development that helps build social and territorial cohesion. The economic development that has taken place in Poland over the last three decades has led to an improvement in road infrastructure throughout the country. Construction of new roads and improvement of existing ones promotes economic development. However, as the number of cars increases, so does the level of air emissions. In reducing pollutant emissions, the analysis of the technological possibilities used and the improvement of their efficiency with the simultaneous minimization of generated pollution is also of particular importance. The purpose of the publication is to present development trends in road transport in Poland and the possibility of reducing emissions in this respect. The method of analysing strategic documents and statistical data was used to achieve this goal. Moreover, the article shows perspectives for reducing the level of emissions from road transpo... [more]

A number of empirical correlations have been achieved between the hydraulic properties measured through geoelectrical methods and water well data of Arak Aquifer located in Markazi province, Iran. The geoelectrical method of Vertical Electrical Sounding (VES) technique was used to calculate the hydraulic properties of the aquifer. Through the VES technique, the pivotal hydraulic properties such as porosity, hydraulic conductivity, and specific yield of the layers were calculated. The results of VES technique were compared with the data obtained from seven observation water wells that were already drilled as exploratory coring boreholes in the region. The results demonstrate that as the porosity and hydraulic conductivity of the water-bearing layer increase, the results of VES technique appear much identical to the water well records. Furthermore, the specific yield was calculated as 4.6% that was very close to the value of 3.5% measured through the previous pumping tests. Moreover, VES... [more]

The main purpose of this paper is to present the differences in the volume of energy consumption in transport in the EU (European Union) countries. The specific objectives aim to determine the directions of changes and the degree of concentration in the volume of energy utilized by the transport sector in EU states, showing various models in this area, to establish the association between energy absorption and the parameters of the economy and in the field of transport. All EU countries were selected for research by the use of the purposeful selection method as of 31 December 2018. The analyzed period covered the years 2004−2018. For the examination of data, grading data analysis was used as one of the methods of multivariate data analysis. Descriptive, tabular and graphic methods were used to present the results. Findings reveal that there is a general tendency to reduce total energy consumption in the EU countries. The same is the case of energy in transport. Only in 2016−2018 was th... [more]

Liquid metal breeding blankets are extensively studied in nuclear fusion. In the main proposed systems, the Water Cooled Lithium Lead (WCLL) and the Dual Coolant Lithium Lead (DCLL), the liquid metal flows under an intense transverse magnetic field, for which a magnetohydrodynamic (MHD) effect is produced. The result is the alteration of all the flow features and the increase in the pressure drops. Although the latter issue can be evaluated with system models, 3D MHD codes are of extreme importance both in the design phase and for safety analyses. To test the reliability of COMSOL Multiphysics for the development of MHD models, a method for verification and validation of magnetohydrodynamic codes is followed. The benchmark problems solved regard steady state, fully developed flows in rectangular ducts, non-isothermal flows, flow in a spatially varying transverse magnetic field and two different unsteady turbulent problems, quasi-two-dimensional MHD turbulent flow and 3D turbulent MHD f... [more]

Many factors influence the prices of energy commodities and the value of energy and fuel companies. Among them there are the following factors: economic, social, environmental and political, and recently also the COVID-19 pandemic. The aim of the paper is to examine what the probability and intensity of a decrease in the prices of shares of energy and fuel companies listed on the Warsaw Stock Exchange (Poland) was during the first wave of the pandemic in the first quarter of 2020. The study used the survival analysis methods: the Kaplan-Meier estimator, the test of equality of duration curves and the Cox non-proportional hazards model. The analysis showed that the probability and intensity of price decline of energy and fuel companies in the initial period was the same as that of other companies. The differences become apparent only after 50 days from the established maximum of their value. The risk of price declines in energy and fuel companies increased significantly. This situation... [more]

Norway is a petroleum exporting country that, simultaneously, is at the forefront of implementing ambitious climate policy measures. Through a discourse analysis of official documents that address petroleum policy, this article examines how the Norwegian government justifies a place for Norwegian petroleum in a low-carbon future. Our findings show that the frames used to justify continued petroleum production between 2011 and 2018 remains predominantly stable, despite the growing opposition to this official discourse in relation to climate change and the societal dependence on petroleum revenues. This article highlights the tension that Norway, as a petroleum-producing country, face in an increasingly carbon-constrained world, and how this is handled in the official petroleum discourse. It shows how the official discourse portrays continued petroleum production and exploration as both valid and necessary and how this framing is discursively linked to a strong commitment to mitigate cli... [more]

One of the biggest problems in applying machine learning (ML) in the energy and buildings field is the lack of experience of ML users in implementing each ML algorithm in real-life applications the right way, because each algorithm has prerequisites to be used and specific problems or applications to be implemented. Hence, this paper introduces a generic pipeline to the ML users in the specified field to guide them to select the best-fitting algorithm based on their particular applications and to help them to implement the selected algorithm correctly to achieve the best performance. The introduced pipeline is built on (1) reviewing the most popular trails to put ML pipelines for the energy and building, with a declaration for each trial drawbacks to avoid it in the proposed pipeline; (2) reviewing the most popular ML algorithms in the energy and buildings field and linking them with possible applications in the energy and buildings field in one layout; (3) a full description of the pr... [more]

Fatigue affects multiple aspects of cognitive performance among drivers. However, even after fatigue builds up, some are still able to maintain the level of behavioral performance. To evaluate these adaptations on the neural network level, we utilized functional magnetic resonance imaging (fMRI). Seventeen male professional drivers underwent two fMRI sessions, once while rested and once in a fatigued condition after 10-h of overnight driving. The cognitive task used in the study involved the detection of visual feature conjunctions, namely the shape and the color. There were no significant differences in the task performance between the conditions except for longer reaction times in the fatigued condition. However, we observed substantial differences in the activation patterns during the cognitive task involving selective attention between the conditions. On the global level, we observed a general decrease in activation strength in the fatigued condition, which appeared to be more pron... [more]

Electric vehicles (EVs) have recently gained momentum as an integral part of the Internet of Vehicles (IoV) when authorities started expanding their low emission zones (LEZs) in an effort to build green cities with low carbon footprints. Energy is one of the key requirements of EVs, not only to support the smooth and sustainable operation of EVs, but also to ensure connectivity between the vehicle and the infrastructure in the critical times such as disaster recovery operation. In this context, renewable energy sources (such as wind energy) have an important role to play in the automobile sector towards designing energy-harvesting electric vehicles (EH-EV) to mitigate energy reliance on the national grid. In this article, a novel approach is presented to harness energy from a small-scale wind turbine due to vehicle mobility to support the communication primitives in electric vehicles which enable plenty of IoV use cases. The harvested power is then processed through a regulation circui... [more]

Thunderstorm downbursts have been reported to cause damage or failure to wind turbine arrays. We extend a large-eddy simulation model used in previous work to generate downburst-related inflow fields with a view toward defining correlated wind fields that all turbines in an array would experience together during a downburst. We are also interested in establishing what role contrasting atmospheric stability conditions can play on the structural demands on the turbines. This interest is because the evening transition period, when thunderstorms are most common, is also when there is generally acknowledged time-varying stability in the atmospheric boundary layer. Our results reveal that the structure of a downburst’s ring vortices and dissipation of its outflow play important roles in the separate inflow fields for turbines located at different parts of the array; these effects vary with stability. Interacting with the ambient winds, the outflow of a downburst is found to have greater impa... [more]

The key issue in the practical implementation of the sliding mode (SM) control−based power inverter is the variable switching frequency. This variable switching frequency not only induces electromagnetic interference (EMI) noise, but also reduces the efficiency of the inverter, as the size of the inductor and capacitor does not alter in tandem with this variable frequency. In this context, fixed switching frequency−based SM control techniques are proposed; however, some of them are too complex, while others compromise the inherent properties of SM control. In this research, a fixed frequency SM controller is proposed, which is based on the novel low-pass filter extraction of the discontinuous control signal. This allows the technique to be implemented with fewer hardware components, thus reducing the complications of implementation, while maintaining the robustness and parametric invariance of SM control. A simulation-based comparison with an existing pulse width modulated (PWM) SM con... [more]

Solid rotor induction machines are still used in high-speed systems. A two-dimensional field-circuit model based on the finite element method and the complex magnetic vector potential has been shown as a very time-effective tool in the analysis of their steady states compared to time-domain models. This continuation work presents a validated computational algorithm that enables the inclusion of the nonsinusoidal and/or asymmetrical voltage supply in the multi-harmonic field-circuit model of these machines that was presented in the previous works by the authors. The extended model accounts for both spatial harmonics due to slotting and/or winding distribution and the time-harmonics due to voltage waveform. The applicability range of the model therefore increases to cases when the machine is supplied with a nonsinusoidal three-phase system of voltages with symmetry or asymmetry that can be decomposed into three symmetrical components. Its short execution time characteristic allows for mu... [more]

The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dolomite on fast pyrolysis vapor upgrading of beechwood was investigated using an analytical pyro probe-gas chromatography/mass spectrometry instrument (Py-GC/MS) at a temperature of 500 °C. Overall, this research showcased that these catalysts can deoxygenate biomass pyrolysis vapors into a mixture of intermediate compounds which have substantially lower oxygen content. The intermediate compounds are deemed to be suitable for downstream hydrodeoxygenation processes and it also means that hydrogen consumption will be reduced as a result of moderate in-situ deoxygenation. Among the support catalysts, the application of hydrotalcite yielded the best results with the formation of moderately deoxygenated compounds such as light phenols, mono-oxy ketones, light furans and hydrocarbons with a TIC area % of 7.5, 44.8, 9.8 and 9.8, respectively. In addition, acids were considerably reduced. Dolomite w... [more]

This paper introduces a novel metaheuristic approach of sooty terns optimization algorithm (STOA) to determine the optimum parameters of model predictive control (MPC)-based deregulated load frequency control (LFC). The system structure consists of three interconnected plants with nonlinear multisources comprising wind turbine, photovoltaic model with maximum power point tracker, and superconducting magnetic energy storage under deregulated environment. The proposed objective function is the integral time absolute error (ITAE) of the deviations in frequencies and powers in tie-lines. The analysis aims at determining the optimum parameters of MPC via STOA such that ITAE is minimized. Moreover, the proposed STOA-MPC is examined under variation of the system parameters and random load disturbance. The time responses and performance specifications of the proposed STOA-MPC are compared to those obtained with MPC optimized via differential evolution, intelligent water drops algorithm, stain... [more]

Heat transfer including heat conduction, thermal convection, and thermal radiation is a major transport process that occurs in various engineering and natural systems such as heat exchangers, solar collectors, nuclear reactors, atmospheric boundary layers, electronical and biomedical systems, and others [...]

Optimal scheduling strategy of integrated energy systems (IES) with combined cooling, heating and power (CCHP) has become increasingly important. In order to make the scheduling strategy fit to the practical implementation, this paper proposes a variable performance parameters temperature−flowrate scheduling model for IES with CCHP. The novel scheduling model is established by taking flowrate and temperature as decision variables directly. In addition, performance parameters are treated as variables rather than constants in the proposed model. Specifically, the efficiencies of the gas turbine and the waste heating boiler are estimated with the partial load factor, and the coefficient of performance (COP) of the electrical chillers and heat pumps are estimated with the partial load factor and outlet water temperature. Then, to deal with the model nonlinearities caused by considering the variability of COPs, the COP-expansion method is developed by adopting a specific representation of t... [more]

Very often, constructors and designers of intelligent building and building automation systems have a choice: to create a compact system with a limited configuration and modifying the system’s behavior possibilities or provide a fully configurable solution at the expense of introducing a full SCADA system equipped with an additional knowledge database and inference system equipped with learning capabilities. In the presented work, we show that there is a third solution. Using a multilayer control system composed of programmable FPGAs, small PCs, and cloud computing resources, we can design and implement a fully configurable intelligent control system for the building’s heating. Our solution combines the compactness of the structure and the ease of installation and assembly.

This paper addresses the challenges the policymakers face concerning the EU decarbonization and total electrification roadmaps towards the Paris Agreement set forth to solve the global warming problem within the framework of a 100% renewable heating and cooling target. A new holistic model was developed based on the Rational Exergy Management Model (REMM). This model optimally solves the energy and exergy conflicts between the benefits of using widely available, low-temperature, low-exergy waste and renewable energy sources, like solar energy, and the inability of existing heating equipment, which requires higher exergy to cope with such low temperatures. In recognition of the challenges of retrofitting existing buildings in the EU stock, most of which are more than fifty years old, this study has developed a multi-pronged solution set. The first prong is the development of heating and cooling equipment with heat pipes that may be customized for supply temperatures as low as 35 °C in h... [more]

Accessories such as joints and terminations represent weak points in HVDC cable systems. The DC field distribution is intimately dependent on the thermal conditions of the accessory and on material properties. Moreover, there is no available method to probe charge distribution in these conditions. In this work, the field distribution in non-stationary conditions, both thermally and electrically, is computed considering crosslinked polyethylene (XLPE) as cable insulation and different insulating materials (silicone, rubber, XLPE) for a 200 kV joint assembled in a same geometry. In the conditions used, i.e., temperatures up to 70 °C, and with the material properties considered, the dielectric time constant appears of the same order or longer than the thermal one and is of several hours. This indicates that both physical phenomena need to be considered for modelling the electric field distribution. Both the radial and the tangential field distributions are analysed, and focus is given on... [more]