Showing papers in "Journal of Renewable and Sustainable Energy in 2018"
TL;DR: A detailed literature review of organosolv pretreatment, focusing on the effects of each of the pretreatment conditions for biorefinery applications, is presented in this article.
Abstract: The concept of a biorefinery that provides valuable bioproducts from biomass conversion instead of fossil based products is presented. One of the main biorefinery products, bioethanol, can be produced from sugar, starch, or lignocellulosic-based biomass. Lignocellulosic-based bioethanol could be a good alternative to sugar- or starch-based bioethanol. While sugar- and starch-based biomass includes mainly glucose or starch, lignocellulosic biomass contains cellulose, hemicellulose, and lignin. While the cellulose is essential for the biomass-to-bioethanol conversion process, hemicellulose and lignin are undesirable in this context, and therefore pretreatment is necessary to break down the lignocellulose structure and separate hemicellulose and lignin from cellulose. Organosolv pretreatment is an attractive method for separating both cellulose and nearly pure lignin from the lignocellulosic material. In a biorefinery, organosolv pretreatment is one of the best options for producing more than one valuable product (bioethanol and lignin) in the same process. For effective bioethanol production, the delignification rate and enzymatic glucose conversion are fundamental parameters. This paper presents a detailed literature review of organosolv pretreatment, focusing on the effects of each of the pretreatment conditions for biorefinery applications. The organosolv pretreatment method is first described in detail and then each of the pretreatment conditions is explored individually. A number of technical studies are reviewed, and the effects of the various conditions on the delignification rate and on enzymatic glucose conversion for effective bioethanol production are described. The current status of development of organosolv-based biorefineries around the world is discussed. In previous reviews of this topic, only the solvent and catalyst effects have been investigated. This review will contribute to the literature by showing the impacts of all pretreatment conditions on pretreatment efficiency.
121 citations
TL;DR: An overview of developments in PSCs is given in, where the authors focus on the synthesis of low bandgap materials and optimization of tandem cells, which led to a power conversion efficiency of ∼13%. Even though this efficiency may not be sufficient enough to compete with that of inorganic solar cells, unique properties of poly(3hexylthiophene-2,5-diyl).
Abstract: For the last two decades, polymer solar cells (PSCs) have been a cynosure of the photovoltaic community, as evidenced by the growing number of patent applications and scientific publications. Efforts to achieve high power conversion efficiency in PSC, propelled by advances in device architecture, material combination, and nanomorphology control, evolved into poly(3-hexylthiophene-2,5-diyl) (P3HT):phenyl-C61-Butyric-Acid-Methyl Ester (PCBM) bulk heterojunction PSCs, which had been the best seller in PSC research for a decade. Subsequently, PSC research was redirected towards the synthesis of low bandgap materials and optimization of tandem cells, which led to a power conversion efficiency of ∼13%. Even though this efficiency may not be sufficient enough to compete with that of inorganic solar cells, unique properties of PSCs, such as mass roll-to-roll production capability, as well as flexibility and lightness, suggest their niche market opportunities. In this review, an overview of developments in PSCs is...
108 citations
TL;DR: An in-depth literature review of Solar cell efficiency, DC-DC power converters, Maximum Power Point Tracking algorithms, solar energy prediction algorithms, microcontrollers, energy storage (battery/supercapacitor), and various design costs for SEH-WSNs is presented.
Abstract: Solar energy harvesting that provides an alternative power source for an energy-constrained wireless sensor network (WSN) node is completely a new idea. Several developed countries like Finland, Mexico, China, and the USA are making research efforts to provide design solutions for challenges in renewable energy harvesting applications. The small size solar panels suitably connected to low-power energy harvester circuits and rechargeable batteries provide a loom to make the WSN nodes completely self-powered with an infinite network lifetime. Recent advancements in renewable energy harvesting technologies have led the researchers and companies to design and innovate novel energy harvesting circuits for traditional battery powered WSNs, such as Texas Instruments Ultra Low Energy Harvester and Power Management IC bq25505 [see https://store.ti.com/BQ25505 for Texas Instruments (TI) Ultra Low Power Boost Charger IC bq25505 with Battery Management and Autonomous Power Multiplexor for Primary Battery in Energy Harvester Applications datasheets (2015).]. In modern days, the increasing demand of smart autonomous sensor nodes in the Internet of Things applications (like temperature monitoring of an industrial plant over the internet, smart home automation, and smart cities) requires a detailed literature survey of state of the art in solar energy harvesting WSN (SEH-WSN) for researchers and design engineers. Therefore, we present an in-depth literature review of Solar cell efficiency, DC-DC power converters, Maximum Power Point Tracking algorithms, solar energy prediction algorithms, microcontrollers, energy storage (battery/supercapacitor), and various design costs for SEH-WSNs. As per our knowledge, this is the first comprehensive literature survey of SEH-WSNs.
88 citations
TL;DR: An attempt of comparing the performance of several energy storage devices such as battery ES, flywheel ES, capacitive ES, superconducting magnetic ES, ultra-capacitors, and redox flow batteries in automatic generation control of an interconnected system finds the superiority of FOPI-FOPID over the others.
Abstract: This paper highlights an attempt of comparing the performance of several energy storage (ES) devices such as battery ES, flywheel ES, capacitive ES, superconducting magnetic ES, ultra-capacitors, and redox flow batteries (RFBs) in automatic generation control of an interconnected system. The considered system comprises conventional thermal, hydro, wind, and solar photovoltaic generations wherein a geothermal power plant (GTPP) is also incorporated. The thermal and hydro systems are provided with appropriate generation rate constraints. A new fractional order (FO) cascade controller named as the FO proportional-integral–FO proportional-integral-derivative (FOPI-FOPID) is proposed as a secondary controller, and its performance is compared with the commonly used classical controllers. A powerful stochastic algorithm called the Sine Cosine Algorithm has been used to optimize the controller gains and other parameters. Analyses of the dynamic responses reveal the superiority of FOPI-FOPID over the others in terms of settling time, peak deviation, and magnitude of oscillation. The effect due to introduction of GTPP has been examined, and the responses disclose that integration of GTPP leads to better dynamics. The comparison of performances of various ES devices in the presence of the FOPI-FOPID controller highlights the predominance of RFB over others.
72 citations
TL;DR: In this paper, a large-eddy simulation (LES) of a wind turbine under uniform inflow is performed using an actuator line model (ALM) for wind energy applications.
Abstract: Large-eddy simulation (LES) of a wind turbine under uniform inflow is performed using an actuator line model (ALM). Predictions from four LES research codes from the wind energy community are compared. The implementation of the ALM in all codes is similar and quantities along the blades are shown to match closely for all codes. The value of the Smagorinsky coefficient in the subgrid-scale turbulence model is shown to have a negligible effect on the time-averaged loads along the blades. Conversely, the breakdown location of the wake is strongly dependent on the Smagorinsky coefficient in uniform laminar inflow. Simulations are also performed using uniform mean velocity inflow with added homogeneous isotropic turbulence from a public database. The time-averaged loads along the blade do not depend on the inflow turbulence. Moreover, and in contrast to the uniform inflow cases, the Smagorinsky coefficient has a negligible effect on the wake profiles. It is concluded that for LES of wind turbines and wind farms using ALM, careful implementation and extensive cross-verification among codes can result in highly reproducible predictions. Moreover, the characteristics of the inflow turbulence appear to be more important than the details of the subgrid-scale modeling employed in the wake, at least for LES of wind energy applications at the resolutions tested in this work.
59 citations
TL;DR: In this paper, numerical simulation and modeling of CZTS-based thin-film kesterite photovoltaic cells using SCAP-1D software is presented, and promising optimized results had been achieved with a conversion efficiency of 23.72%, a fill factor of 82.54%, a shortcircuit current (J s c ) of 44.87 mA / cm 2, and an open circuit voltage (V o c) of 0.64V.
Abstract: C u 2 ZnSn S 4 ( CZTS ) is a non-toxic earth abundant material and a promising quaternary semiconductor compound of groups I − I I − I V − V I having a kesterite symmetrical structure. Due to its optimum direct bandgap, it has been considered as a suitable material for absorber layers for photovoltaic cell applications. This paper presents the numerical simulation and modeling of CZTS based thin film kesterite photovoltaic cells using SCAP-1D software. The influence of device parameters such as the carrier concentration, thickness, densities of absorber, buffer and window layers, defect densities and the temperature effect on the performance of the Z n O / C d S / CZTS / M o photovoltaic cell structure are analyzed. Defect densities are added to the absorber layer and the interface between the buffer layer and the absorber layer. This type of solar cell does not comprise any toxic material and can lead to non-toxic thin film photovoltaic cells with outstanding optical properties. In this work, promising optimized results had been achieved with a conversion efficiency of 23.72%, a fill factor of 82.54%, a short-circuit current ( J s c ) of 44.87 mA / cm 2, and an open circuit voltage ( V o c ) of 0.64V.
57 citations
TL;DR: In this paper, a well-aligned hierarchical NiMoO4 nanorod is successfully grown on nickel foam by a facile hydrothermal method, which can be directly used as integrated electrodes for supercapacitors without the addition of other ancillary materials such as binders or additives to enhance electrode cycling stability or conductivity.
Abstract: Well-aligned hierarchical NiMoO4 nanorods are successfully grown on nickel foam by a facile hydrothermal method, which can be directly used as integrated electrodes for supercapacitors without the addition of other ancillary materials such as binders or additives to enhance electrode cycling stability or conductivity. The samples are characterized by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements. The achieved NiMoO4 nanorods are uniformly grown on nickel foam with the average diameter of 100 nm and length of 3 μm. The results indicate that the NiMoO4 nanorod samples deliver high specific capacitances of 3412, 2490, 1740, and 1496 F/g at 1, 4, 7, and 10 A/g, respectively. Furthermore, the excellent rate capability of the NiMoO4 nanorod based supercapacitors has been obtained in the KOH electrolyte, demonstrating that the as-prepared products can be promising electrode materials for supercapacitors.
50 citations
TL;DR: Critical observation reveals the superiority of the meta-heuristic algorithm, whale optimization algorithm, in terms of peak deviations and settling time for the T-G system under both step load perturbation and random load perturbedation.
Abstract: The present article deals with automatic generation control of a three-area multi-source thermal-gas (T-G) system with integration of distributed generation (DG), electric vehicles (EVs), and energy storage devices. Each thermal unit is equipped with a single reheat turbine, a generation rate constraint, and a governor dead band. A cascade combination of two degree of freedom proportional-integral-derivative with a filter (2DOF-PIDN) and a fractional order integrator controller [(2DOF-PIDN)-FOI] is proposed as the secondary controller for the system. A meta-heuristic algorithm, whale optimization algorithm, is utilized for simultaneous optimization of gains and other parameters of controllers PIDN, PIDN-FOI, and (2DOF-PIDN)-FOI. Critical observation reveals the superiority of the latter in terms of peak deviations and settling time (ST) for the T-G system under both step load perturbation and random load perturbation. Eigen value analysis is also performed for the T-G system with and without secondary con...
47 citations
TL;DR: In this article, the authors summarize the classification of Savonius wind turbines according to the blade profile and present the development of this promising low speed generator, which can not only present the effect of key design parameters on rotor's performance, but also obtain the functional features of different profiles and the comparison among different profiles.
Abstract: The utilization of urban wind energy through small wind turbines has become an arising technology to ease the conflicts between rising energy demands in buildings and depletion of traditional energy resources Many studies have reported that drag type vertical axis wind turbines have superior performance in the unsteady wind because of their attractive features Several review studies have been conducted on these turbines They mainly focused on the geometrical design parameters, the flow patterns, the research methodology, and the wind tunnel blockage correction However, less research has been conducted to classify the Savonius rotor based on the classification criterion of the blade profile and has made a comprehensive performance comparison between different types of Savonius rotors The blade profile is the essential design issue for a Savonius rotor; therefore, the variation of the blade profile will change the design parameters and affect the rotor's performance significantly So, the classification based on the blade profile can not only present the effect of key design parameters on rotor's performance for each blade profile easily but also obtain the functional features of different profiles and the comparison among different profiles Hence, in this article, we aim to summarize the classification of Savonius wind turbines according to the blade profile and present the development of this promising low speed generator
43 citations
TL;DR: In this paper, an attempt has been made to review the utilization of agro-waste derived ashes as heterogeneous catalysts and metal loaded ash catalysts in synthesis of biodiesel through transesterification reaction of various oil feedstocks.
Abstract: Agro-wastes are the post-harvest products or agricultural residues generated through various agricultural activities which have diverse scopes for various applications. Reutilization of agro-waste is an environmentally safe and cost-effective process of waste management. Proper and optimal utilization of these waste by-products is one of the major challenges for the human society nowadays. The recent trend around the globe is to transform waste into different products useful for various applications. Agro-waste derived ashes have recently been extensively studied as the heterogeneous base catalysts in biodiesel synthesis which is attracting increasing attention worldwide. Agro-waste derived catalysts are easily available, simple to prepare, easy to handle, biodegradable, non-toxic, more environmentally benign, and more cost-effective. In this study, an attempt has been made to review the utilization of agro-waste derived ashes as heterogeneous catalysts and metal loaded ash catalysts in synthesis of biodiesel through transesterification reaction of various oil feedstocks. Several parameters like the calcination temperature, catalyst amount, ratio of methanol to oil, reaction times, and temperatures which affect the transesterification reaction were also briefly discussed herein. The agro-waste derived heterogeneous base catalysts are highly active for catalysing transesterification of oil to biodiesel with a shorter reaction time and higher conversion up to 100% as compared to commercial catalysts and other catalysts derived from other renewable biomasses such as egg shells, fish scales, and bones. Further, the performance of agro-waste derived heterogeneous base catalysts is better and more efficient than that of the metal source loaded ash catalysts. The high activities of these catalysts are due to the higher potassium content which is accrediting their high basicity. Moreover, efficient utilization of waste materials will help to reduce global warming and enhance the clean and clear environment in the society.
41 citations
TL;DR: In this paper, a review of Pakistan's energy dynamics and the potential of renewable energy resources is explored, which reveals that biomass energy could help to achieve the target of increasing the share of renewables in energy mix from less than 1% to 5% by 2030 as envisaged by the Government of Pakistan.
Abstract: Pakistan is a developing economy with a mainstay shifting gradually from agriculture to industry. Improving lifestyles, population growth, and rapid urbanization have led to a continuous increase in the demand of energy. The demand-supply gap amounts to 5000 MW on average which reaches 7000 MW in the month of July when the energy demand is at peak. This shortfall causes 4%–7% loss to the gross domestic product. Energy demand is at a constant peak of 8%–10% per annum. Fossil fuels make 61% of energy mix, while the share of renewables is less than 1%. This situation calls for careful analysis and review of Pakistan's energy dynamics and to explore the potential of renewable energy resources. Biomass, a promising resource of renewable energy, is abundantly available in Pakistan. Biomass is found in various forms from firewood to crop residues to municipal solid waste. About 50% of domestic energy requirements are fulfilled by fuelwood and 34% by animal and crop residues. However, the availability of fuelwood reduces as the rate of growth of forests has shrunk to 8.8%. Other biomass resources like charcoal are used at the minor level. Bagasse produced by 70 sugar industries in the country has been found to be sufficient for the generation of 5700 GWh of electricity. Major crop residues include cotton stalks, wheat straw, rice straw, sugarcane trash, and corn stalk having production of 49.4, 34.581, 16.75, 7.83, and 5.325 million tons, respectively. Collective processing residues per annum of these crops amount to 25.271 million tons having a power generation potential of 689.25 TWh annually. Animal dung also offers encouraging potential of power generation. The total number of animals in the country is 51 million. The potential of electricity generation from animal dung at the national level has been estimated to be 4761 to 5554 MW. The municipal solid waste potential for production of energy by biochemical and thermochemical conversion is 216 kWh/t and 552 kWh/t, respectively. It was found that the country possesses potential of successfully running 15 million biogas plants. This review, which policymakers and researchers may find to be useful, revealed that biomass energy could help to achieve the target of increasing share of renewables in energy mix of the country from less than 1% to 5% by 2030 as envisaged by the Government of Pakistan.
TL;DR: The proposed wind prediction model feeds the ranked features into a deep learning prediction system enabled by RNN, whose neurons have self-feedback loops to help gather the past decisions, and thus be more effective than FNN for wind power prediction.
Abstract: There are many features that have been taken into consideration for wind power forecasting. Since properly ranking these relevant features, often redundant, can be quite difficult, highly accurate short term wind power forcasting remains a big challenge. Another noted problem that adversely impacts the accuracy of wind forcasting stems from the weakness of the prevailing prediction models based on the feedforward neural network (FNN) in handling wind power time series. This paper thus attempts to address the aforementioned problems in short-term wind power forecasting with a novel approach that combines the infinite feature selection (Inf-FS) with the recurrent neural networks (RNN). In particular, all the possible features related to wind forecast are first clustered into multiple feature sets, after which the identified feature sets are mapped onto the paths of a graph built for Inf-FS. Traversing such a graph helps effectively determine/rank the significance of the features according to their stability and classification accuracy measured in the feature space. The proposed wind prediction model then feeds the ranked features into a deep learning prediction system enabled by RNN, whose neurons have self-feedback loops to help gather the past decisions, and thus be more effective than FNN for wind power prediction. The proposed wind power prediction approach is demonstrated through the experimental evaluations using a dataset from the National Renewable Energy Laboratory (NREL). The result shows that the accuracy of short-term wind power forecast is increased by 11%, 29%, 33%, and 19% in spring, summer, autumn and winter, respectively, over that achieved using the traditional approaches.
TL;DR: In this article, the impact of atmospheric stability on wake parameters like the wake length was investigated in the German Bight, and it was shown that in this area stable atmospheric conditions favour longer wakes.
Abstract: C-band and X-band Synthetic Aperture Radar (SAR) data acquired by the Sentinel-1 and TerraSAR-X satellites are used to study atmospheric wakes behind offshore wind parks in the German Bight. A particular focus is on the impact of atmospheric stability on wake parameters like the wake length. Stability parameters are estimated from measurements taken at the FINO-1 observation platform. Based on a data set covering different seasons and concentrating on the first German offshore wind park Alpha Ventus (AV), it is shown that in this area stable atmospheric conditions favour longer wakes. This is first demonstrated for situations, where the wake behind AV was unperturbed by other neighbor wind parks. In this case, wakes of more than 30 km length are observed. In a second step, the more complicated situation with wake superposition from different neighboring wind parks is analysed. It is shown that in this case, the merged wakes can extend to more than 70 km downstream.The analysis is challenged by two factors. First of all, the FINO-1 platform is within the wind farm wakes for a certain range of wind directions. This means stability estimates for the upstream conditions are not straightforward to obtain in these conditions. The second complication is associated with an apparent increase in the radar cross section downstream of wind parks observed on many SAR scenes, typically within the first 10 km downstream the wind park. A semi-empirical model is proposed to explain this effect by an increased downward momentum flux associated with increased turbulence generated by the wind park. Applying numerical inversion methods, a couple of typical downstream wind speed profiles are reproduced with this model based on SAR derived estimates of the friction velocity.
TL;DR: The results demonstrate that the proposed stochastic model can successfully optimize cogeneration of a hydro-thermal-wind-solar system and minimize energy cost in the network.
Abstract: This paper optimizes cogeneration of a hydro-thermal-wind-solar system. In the proposed hybrid system, the energy storage systems are also incorporated to smooth out the fluctuations of renewable energies. The uncertainties of wind and solar powers are included, and stochastic programming is adopted to deal with the uncertainties. The hydro system comprises two cascade reservoirs. The optimal scheduling of both reservoirs is presented, and the electricity generated by each reservoir is optimized. The optimal scheduling of thermal unit is also determined. The optimal location, capacity, power, and charging-discharging pattern are determined for battery energy storage systems. The simulations are carried out using an IEEE 69-bus distribution network, and the model is implemented in GAMS software and solved as a mixed integer linear programming. The objective of the problem is to minimize energy cost in the network. The results demonstrate that the proposed stochastic model can successfully optimize cogenera...
TL;DR: This paper deals with optimal arbitrage of DSSs in ADNs including the solar/wind/CHP hybrid energy system aiming at finding the optimal trade-off between congestion and economic targets by defining a novel probabilistic risk-based multi-objective model.
Abstract: Nowadays, dispersed storage systems (DSSs) have an irrefutable role in creating the favourable substrates for optimal management of active distribution networks (ADNs). Actually, they are capable of managing the congestion of ADNs by providing feasible solution that can dramatically improve the system reliability and resiliency against contingencies that threaten the network security. To this end, this paper deals with optimal arbitrage of DSSs in ADNs including the solar/wind/CHP hybrid energy system aiming at finding the optimal trade-off between congestion and economic targets by defining a novel probabilistic risk-based multi-objective model. In particular, the proposed method is fulfilled considering (1) feeders/line congestions, (2) network voltage deviations, (3) power losses, (4) operating cost of distributed generation associated with the cost of DSS charging/discharging, and (5) uncertainty pertaining to renewable generation. The two conflicting objectives consisting of congestion alleviation and procurement cost minimization are optimized simultaneously by multiobjective particle swarm optimization to purvey the Pareto-optimal curve, and subsequently, fuzzy decision-making is executed to extract the best solution from the Pareto curve obtained with respect to defined risk-based strategies. Finally, a case study referring to the modified IEEE 33-bus distribution system is utilized to evidence the efficiency and proficiency of the proposed congestion relief approach.Nowadays, dispersed storage systems (DSSs) have an irrefutable role in creating the favourable substrates for optimal management of active distribution networks (ADNs). Actually, they are capable of managing the congestion of ADNs by providing feasible solution that can dramatically improve the system reliability and resiliency against contingencies that threaten the network security. To this end, this paper deals with optimal arbitrage of DSSs in ADNs including the solar/wind/CHP hybrid energy system aiming at finding the optimal trade-off between congestion and economic targets by defining a novel probabilistic risk-based multi-objective model. In particular, the proposed method is fulfilled considering (1) feeders/line congestions, (2) network voltage deviations, (3) power losses, (4) operating cost of distributed generation associated with the cost of DSS charging/discharging, and (5) uncertainty pertaining to renewable generation. The two conflicting objectives consisting of congestion alleviation an...
TL;DR: An overview of the applications of Genetic Algorithms, Fuzzy logic, Particle Swarm optimization, and similar other evolutionary and nature inspired algorithms that have been employed for the optimization, control, and power management strategies for renewable energy studies involving hybrid power generation schemes is presented.
Abstract: Hybrid renewable energy systems (HRESs) can alleviate the grid dependence for power in rural and distant locations. The intermittent nature of renewable energy sources acting alone does not make the system reliable; however, combining one or more sources (like solar, wind, diesel, biomass, micro-hydel, etc.) with adequate storage options or intelligent control of hybrid systems ensures power availability to the end user. As a result, it is imperative that the technical aspects of such a hybrid system can be analyzed with respect to optimal sizing of sources, proper control design and mechanism for energy management, and adequate backup via the storage option that ascertain reliable power supply to the consumer/end user or at the distributed generation end. This paper presents an overview of the applications of Genetic Algorithms, Fuzzy logic, Particle Swarm optimization, and similar other evolutionary and nature inspired algorithms that have been employed for the optimization, control, and power management strategies for renewable energy studies involving hybrid power generation schemes. Analysis of the algorithms and the potential applications of new improved algorithms for optimization, control, and power management of HRES is discussed and reported.
TL;DR: A rolling prediction model combining Empirical Mode Decomposition (EMD) and Artificial Neural Network (ANN) techniques with the need for historical solar radiation data only is proposed, and it can be used to predict long-term solar radiation.
Abstract: Long-term prediction of solar radiation intensity plays an important role in the planning and design of photovoltaic power stations. Unlike previous research on solar radiation prediction requiring various meteorological and topographic data, this study proposed a rolling prediction model combining Empirical Mode Decomposition (EMD) and Artificial Neural Network (ANN) techniques with the need for historical solar radiation data only. To overcome the inconsistency problem of the number of intrinsic mode functions derived from the EMD, they are classified into high-frequency term, low-frequency term, and trend item, which are taken as the input parameters of the ANN model. With the historical data one-year after as the output parameter, the ANN model implies the complex, non-linear relationship between the adjacent periods, and it can be used to predict long-term solar radiation. The proposed methodology is applied to Gonghe county in the Qinghai province of China, where a large-scale photovoltaic power pla...
TL;DR: In this article, the authors examined the factors influencing consumers' intention to use renewable energy technologies for household usage in Pakistan and found that factors such as subjective norm, perceived behavioural control, and attitude positively influence consumers' intentions to use renewables in Pakistan, whereas cost has the opposite effect.
Abstract: Adoption of renewable energy technologies is a complex and intricate process affected by a multitude of factors. The objective of this study is to examine the factors influencing consumers' intention to use renewable energy technologies for household usage in Pakistan. In order to understand the adoption behaviour, we have extended the actual framework of the theory of planned behaviour by integrating three additional factors, i.e., environmental concern, cost, and awareness. The findings of this research are based on primary data collected from 244 households in the twin cities of Islamabad and Rawalpindi through survey questionnaires. The proposed hypotheses were then tested and analysed using structural equation modelling. The results reveal that factors such as subjective norm, perceived behavioural control, and attitude positively influence consumers' intention to use renewable energy technologies in Pakistan, whereas cost has the opposite effect. Interestingly, awareness and environmental concern were found to be insignificant. The results of this study highlight the need to increase environmental awareness, frame innovative financing mechanisms, and address the benefits that renewable energy technology offers, all through an integrative and coherent effort.
TL;DR: In this article, the authors used the Random Forest Algorithm in WEKA to forecast the post-consecutive years one by one with the pre-consequent years which includes the preforecasted years.
Abstract: Solar energy and the concept of passive solar architecture are being increased in several areas to attain the net-zero energy concept. This paved the way for an increase in the need of solar irradiance forecasting for both solar PV applications and Passive Solar Architectural buildings. First, solar irradiance forecasting was done with 131 400 data sets (1-h data for 15 years) which was split into monthly mean for every year. This model was evaluated by forecasting the post-consecutive years one by one with the pre-consecutive years which includes the pre-forecasted years. This model was shown to have RMSE values of 11% to 24% for various seasonal forecasting using the Random Forest Algorithm in WEKA, which gave the annual irradiance results nearer to the PV Sol energy forecasting results. The R-value was in the range of 0.8 to 0.9 for various seasons which is good. Building Energy Optimization was carried out using BEopt 2.8 software designed by NREL. The chosen building was set to the standard parameters in India, and then, the optimization was done with various customized parameters and systems available in India to reduce the energy consumption from 192.2 MMBtu/yr to 109.1 MMBtu/yr with a 7 kW Solar PV System to attain the net-zero energy concept.
TL;DR: In this paper, a road piezoelectric transducer (PZT-5H) was used as the core component of a road PZT to generate electric energy in road pavement.
Abstract: This article demonstrates the design of a road piezoelectric transducer (PZT) through a laboratory load test, to utilize the load mechanical energy in road. PZT-5H was selected as the piezoelectric vibrator material. With the combination of the action property of low-frequency forced vibration of the pavement vehicle wheel load, a simple supported disk lap piling piezoelectric vibrator was used as the core component of the road piezoelectricity generating set. The tracking wheel-pressure test of a beam piece was used to determine the piezoelectricity generating capacity of road pavement. The maximum voltage that could be reached is 65.2 V. The primary wheel rolling impact could produce an electric energy of 0.23 mJ. The electric capacity of 0.8 kW/h could be produced per day, which can meet the demand of signal lights.
TL;DR: In this article, the physicochemical properties of pyrolysis of three waste biomass, viz., pinewood sawdust, sal wood sawdust and Areca Nut husk powders, were reported.
Abstract: This work reports the kinetics and pyrolysis characteristics of three waste biomass, viz., pinewood sawdust, sal wood sawdust, and Areca Nut husk powders. Pyrolysis was conducted with five different heating rates of 5 °C min−1–25 °C min−1 under an inert atmosphere. The burnout temperatures and physicochemical properties of the three biomass were reported in this work. The results indicated that heating rates widely affected the burnout temperatures during combustion. When heating rates increased, the burnout temperatures shifted towards the higher temperature region. It was observed that kinetic parameters and degradation rates were functions of heating rate and temperature. However, activation energy varied with the change in heating rates. The activation energy, pre-exponential factor, and derivative of thermogravimetric analysis (TGA) (DTG) characteristics were affected by the rise in heating rates. At higher heating rates, DTG peaks shifted to the higher temperature region, but it does not affect the ...
TL;DR: In this article, a thermally stratified wind turbine array boundary layer is studied in detail using a combination of Lumley and barycentric maps together with the recently introduced spheroid and color maps.
Abstract: In the interest of understanding the dynamics and energy transfer between the atmospheric boundary layer and large wind turbine arrays, a description of the turbulence anisotropy in the wake region of wind turbines is necessary. Flux of high momentum flow into the wind turbine array by anisotropic turbulence is a dominant factor of mean kinetic energy resupply for the wind farm. Under thermal stratification, the behavior of the turbulence field, and the energy flux, is significantly altered. Here, a thermally stratified wind turbine array boundary layer is studied in detail using a combination of Lumley and barycentric maps together with the recently introduced spheroid and color maps. The atmospheric flow is modelled using a large eddy simulation driven by a constant geostrophic wind and a time-varying ground surface temperature, obtained from a selected period of the Cooperative Atmosphere-Surface Exchange Study-99 field experiment. The wind farm is modelled using the traditional actuator-disk with rota...
TL;DR: In this article, the performance implications of the choice of structure used to mount turbine blades to the central shaft were examined experimentally in a recirculating water flume and it was found that using foil cross-section struts located at the turbine blade tips resulted in the highest turbine performance.
Abstract: Cross-flow or vertical-axis turbines are flow energy conversion devices in which lift forces cause blades to rotate around an axis perpendicular to the flow. In marine currents, rivers, and some wind energy applications, cross-flow turbines are a promising alternative to more conventional axial-flow turbines. The performance implications of the choice of structure used to mount turbine blades to the central shaft are examined experimentally in a recirculating water flume. Turbine performance is found to be strongly dependent on the choice of the mounting structure. Power loss due to rotational drag on these structures is estimated experimentally by rotating the mounting structure without blades. Through a perturbation-theory approach, interactions between turbine blades and mounting structures are examined. Analytical models for the power loss due to mounting structure drag are introduced and shown to be consistent with experiments. To provide guidance for cross-flow turbine design, the models are re-formulated in terms of non-dimensional turbine geometric and operational parameters. Mounting blades solely at their mid-span is shown to decrease performance through multiple fluid effects. Using foil cross-section struts located at the turbine blade tips is found to result in the highest turbine performance.
TL;DR: In this article, a new pattern of positioning the PV module using the Latin square pattern without changing the total cross tied electrical connection was proposed, which disperses the shading uniformly within the given PV array which reduces mismatch losses significantly and increases the generation of power.
Abstract: Partial shading in a solar array deteriorates the maximum power generated owing to the voltage mismatch and current mismatch of the shaded solar PV module. Also, partial shading primes to multiple peaks in the P-V characteristics of the solar PV array and it has become more complex to track the Maximum Power Point (MPP). To enhance the maximum power generated by means of reducing mismatch losses, several reconfiguration techniques were suggested earlier. The mismatch losses depend not only on the amount of the area shaded but also on the shading pattern and array arrangement. This paper proposes a new pattern of positioning the PV module using the Latin square pattern without changing the total cross tied electrical connection. The proposed pattern disperses the shading uniformly within the given PV array which reduces mismatch losses significantly and increases the generation of power. The shade dispersion using proposed pattern also eliminates multiple peaks in its PV curve which enables the use of a simple algorithm to track MPP. This Latin square pattern is studied under different partial shading conditions, and the results exhibit improved performance under partial shading conditions.Partial shading in a solar array deteriorates the maximum power generated owing to the voltage mismatch and current mismatch of the shaded solar PV module. Also, partial shading primes to multiple peaks in the P-V characteristics of the solar PV array and it has become more complex to track the Maximum Power Point (MPP). To enhance the maximum power generated by means of reducing mismatch losses, several reconfiguration techniques were suggested earlier. The mismatch losses depend not only on the amount of the area shaded but also on the shading pattern and array arrangement. This paper proposes a new pattern of positioning the PV module using the Latin square pattern without changing the total cross tied electrical connection. The proposed pattern disperses the shading uniformly within the given PV array which reduces mismatch losses significantly and increases the generation of power. The shade dispersion using proposed pattern also eliminates multiple peaks in its PV curve which enables the use of a si...
TL;DR: In this paper, the authors used CuFe2O4 spinel as an oxygen carrier (OC) in chemical looping gasification (CLG) of solid fuels (biomass or coal) is an effective gasification technology.
Abstract: Chemical looping gasification (CLG) of solid fuels (biomass or coal) is an effective gasification technology. In this work, CuFe2O4 spinel was used as an oxygen carrier (OC) in CLG. Coal and biomass char heat-treated at 600 °C, 700 °C, and 800 °C were used as fuels. The reactivity of char heat-treated at 600 °C and OC was studied using thermogravimetry. The results showed that the optimal mass ratio of OC/char is 6:4. Under this condition, the highest reactivity of char heat-treated at 600 °C was obtained. The gas composition was tested in a fixed bed at various OC/char mass ratios (7:3, 6:4, 5:5, 4:6, and 3:7). The CO yield increases with the decrease in the oxygen carrier ratio. An opposite trend was observed in the CO2 yield. In addition, six kinetic models were used to study the mechanism of CLG. The modified random pore model is found to be optimum in describing experimental data. The results showed that the OC/char in CLG is influenced by pores and catalytic active sites.
TL;DR: In this article, the authors describe possibilities to standardize the production under laboratory conditions by eliminating distorting factors, such as the pressure by which the glass plates with conductive coatings, serving as electrodes, are pushed together to close the solar cell.
Abstract: Dye-sensitized solar cells are subject to intensive research nowadays. Their open-circuit voltage, short-circuit current, and efficiency depend on several parameters which can be optimized. Here, examinations are limited to non-toxic substances due to planned future application on textile fabrics, i.e., to TiO2, graphite, and natural dyes. During experiments on the TiO2 layer, the reproducibility of the experiment turned out to be a crucial factor, limiting the significance of the experimental findings. Thus, the main goal of this paper is the description of possibilities to standardize the production under laboratory conditions by eliminating distorting factors. Specifically, the pressure by which the glass plates with conductive coatings, serving as electrodes, are pushed together to close the solar cell was found to significantly influence the results. Different possibilities were hence tested to normalize this pressure, including different clamps and magnets. In the optimal setup, the deviations betwe...
TL;DR: In this article, a new model of the hybrid system consisting of a photovoltaic (PV) array and thermally regenerative electrochemical cycles (TRECs) is proposed to improve the conversion efficiency of solar energy, where the temperature of the PV array is determined by the energy balance equation.
Abstract: A new model of the hybrid system consisting of a photovoltaic (PV) array and thermally regenerative electrochemical cycles (TRECs) is proposed to improve the conversion efficiency of solar energy, where the temperature of the PV array is determined by the energy balance equation. Analytical expressions for the power output, efficiency of the PV array, TRECs, and hybrid system are derived. The influences of the voltage output of the PV array, the electric current of TRECs, the solar irradiation, and the numbers of TRECs on the efficiency of the hybrid system are discussed in detail. The maximum efficiency of the hybrid system is numerically calculated and the corresponding parameters are determined. The results obtained here show that TRECs can efficiently utilize the waste heat from the PV array.
TL;DR: In this article, the performance of the double basin single slope solar still has been evaluated for the various water depths at the location of 20.61° N, 72.91° E.
Abstract: In the present era, pure water scarcity is one of the biggest dilemmas. A solar still may be the best solution to solve the water problem in remote areas. But due to its lower efficiency, the device is not quite commercialized. A single basin single slope solar still is simple and economical, but it has a very low yield of distilled water. A double basin single slope solar still may enhance the productivity of the solar still by utilizing the latent heat of condensation which is lost in the atmosphere in the single basin single slope solar still. In the present paper, the performance of the double basin single slope solar still has been evaluated for the various water depths at the location of 20.61° N, 72.91° E. The yield of the solar still has been measured for the various depths of saline water in the lower basin such as 0.01 m, 0.02 m, 0.03 m, and 0.04 m. From the experimental results, the daily distillate of 2.024 l, 1.944 l, 1.892 l, and 1.792 l per m2 of the basin area and the overall efficiency of 24.56%, 24.00%, 23.33%, and 21.89% were obtained for the water depths of 0.01 m, 0.02 m, 0.03 m, and 0.04 m in the lower basin, respectively.
TL;DR: In this article, the authors present the influence of solidity on the aerodynamic performance of H-rotor VAWTs immersed in turbulence via wind tunnel tests and investigate the relationship between the turbine's power coefficient, CP, and BSR, λ, at different turbulence levels.
Abstract: Recent research suggests that vertical axis wind turbines (VAWTs) are suitable for urban installations. Nevertheless, systematic investigation of the power performance of VAWTs operating in flows of various turbulence levels remains limited. This study presents the influence of solidity on the aerodynamic performance of H-rotor VAWTs immersed in turbulence via wind tunnel tests. Homogeneous turbulence of various levels was generated by a wooden grid. A turbine control system was used to tune the blade speed ratio (BSR) and measure the rotational speed and torque. The relationship between the turbine's power coefficient, CP, and BSR, λ, was examined at different turbulence levels, I. Further, the impact of changes in the solidity ratio, σ, on the CP–λ curve was investigated. The analysis results show that the CP value of the turbine in turbulent flows was, on average, two times that of the one in smooth flow. However, a simple relationship between the increase in turbulence intensity and the increase in po...
TL;DR: In this article, the authors investigate the energy production of two vertical axis wind turbines (VAWTs) arranged in a side-by-side configuration for five different rotor distances and three combinations of rotational directions.
Abstract: The present study is intended to investigate the energy production of two vertical axis wind turbines (VAWTs) arranged in a side-by-side configuration for 5 different rotor distances and three combinations of rotational directions. The studied two-bladed rotor is constructed by the NACA 0021 airfoil with a radius of 1 m and operates at a wind speed of 8 m/s. Computational Fluid Dynamics approaches are employed in these analyses using the Menter SST turbulence model, and the simulations agree well with the available measurement data for a single rotor. The investigations reveal that the attained power of the two VAWT rotors depends strongly on the distance of the turbines and the direction of the rotor rotation. Load fluctuations are further examined in the present study. The performance improvement and vortex shedding of the dual-rotor system depend strongly on the tip speed ratio. An improved performance of the rotor can be achieved by considering the mentioned parameters, and layouts of the turbine array are designed based on these studies.