Trends in Renewable Energy
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Production of Biochar Based Porous Carbon Nanofibers for High-Performance Supercapacitor Applications
Get PDFBiomass-derived biochar was used as the precursor to synthesize porous carbons for supercapacitor electrodes. The biochar was first activated with KOH to generate porous carbon material and then fabricated into highly flexible porous carbon nanofibers (ECNF) by electrospinning technique. Activated carbons with a surface area of around 2258 m2/g were found. The resultant biochar based ECNF mats exhibited outstanding mechanical flexibility and electrochemical properties as free-stranding and binder free electrodes of supercapacitor. The PAN/BCK3 ECNFs, which were made from the composite of polyacrylonitrile (PAN) and KOH-activated biochar (mass ratio of Biochar/KOH =1:3) exhibited the highest gravimetric capacitance (108 F/g at current density of 0.5 A/g) with high retention (96% at 1 A/g) due to its well-developed micro-mesoporosity. The results indicated that biomass-derived biochar is a promising material which can be used for the production of low cost high performance electrode materials for supercapacitor. Citation: Xiu, S., Gbewonyob, S., Shahbazi, A., and Zhang, L. (2019). Production of Biochar Based Porous Carbon Nanofibers for High-Performance Supercapacitor Applications. Trends in Renewable Energy, 5, 151-164. DOI: 10.17737/tre.2019.5.2.009
Catalytic Pyrolysis of Kapok Fiber for Production of Olefins
Get PDFPyrolysis of kapok fibers over mesoporous molecular sieves of MCM-41, Zr-MCM-41 and Cr-MCM-41 (the mole ratio of Si:Zr or Si/Cr=50) was studied by using pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Pure silicon MCM-41 showed weak acidity during pyrolysis with furfural as the main product. Zr-MCM-41 showed the dual-functionality of acid and base with both furfural and hydroxy acetone present in the products. Cr-MCM-41 was more acidic with more furfural produced. The optimal conditions for producing olefins were found to be 600°C and the ratio of kapok fiber to catalyst being 1:10 with the Zr-MCM-41 catalyst. The main products obtained via pyrolysis of kapok fiber were acetic acid, furfural, 2,4-di-tert-butylphenol, olefins, and alkanes. The excess of the catalyst and the high temperature of the reaction had certain effects on the pyrolysis of biomass to produce olefins, such as 1-decene, 1-dodecene, 1-undecene, 1-tridecene and heptadecane. Citation: Qiu, Q., Cai, Y., Ye, Q., and Lv, W. (2019). Catalytic Pyrolysis of Kapok Fiber for Production of Olefins. Trends in Renewable Energy, 5, 218-228. DOI: 10.17737/tre.2019.5.2.009
Virtual Indicative Broadband over Power Lines Topologies for Respective Subclasses by Adjusting Channel Attenuation Statistical Distribution Parameters of Statistical Hybrid Models (Class Maps) - Part 3: The Case of Overhead Transmission Power Grids
Get PDFIn [1], [2], the theoretical framework and the numerical results concerning the class mapping of overhead and underground medium voltage broadband over power lines (OV and UN MV BPL) topologies have been presented on the basis of the recently proposed initial statistical hybrid model (iSHM), modified statistical hybrid model (mSHM) and class map definition procedure. In this paper, all the recent findings regarding the statistical channel modeling and class mapping are first applied to transmission BPL networks; say, OV high voltage (HV) BPL topologies. The numerical results of OV HV BPL networks are compared against the respective ones of OV and UN distribution networks revealing significant similarities and differences. Finally, the impact of considering minimum or maximum capacity value instead of the average one during the definition procedure is investigated as well as the behavior of the total simulation time of class mapping.Citation: Lazaropoulos, A. (2019). Virtual Indicative Broadband over Power Lines Topologies for Respective Subclasses by Adjusting Channel Attenuation Statistical Distribution Parameters of Statistical Hybrid Models (Class Maps) - Part 3: The Case of Overhead Transmission Power Grids. Trends in Renewable Energy, 5(3), 282-306. doi:http://dx.doi.org/10.17737/tre.2019.5.3.0010
Enhancing the Statistical Hybrid Model Performance in Overhead and Underground Medium Voltage Broadband over Power Lines Channels by Adopting Empirical Channel Attenuation Statistical Distribution
Get PDFStatistical hybrid model is a statistical channel model suitable for the broadband over power lines (BPL) networks while it is based on the statistical processing of channel attenuation and capacity values of preassumed BPL topology classes. One of the key operation elements of the statistical hybrid model, which affects its results fidelity, is the selection of the appropriate channel attenuation statistical distribution among a set of well-known channel attenuation statistical distributions (i.e., such as Gaussian, Lognormal, Wald, Weibull and Gumbel distributions). The selection of the appropriate channel attenuation statistical distribution becomes a hard task since it depends on a number of factors such as the power grid type -either overhead (OV) or underground (UN) power grid-, the representative distribution BPL topology of the examined class, the applied electromagnetic interference (EMI) policies and the used coupling scheme type. The contribution of this paper is to identify the conditions whether the Empirical channel attenuation statistical distribution can act as the default distribution of statistical hybrid model (modified statistical hybrid model) thus replacing the required comparison analysis prior to the selection of the aforementioned distributions of the initial statistical hybrid model. The evaluation comparison is based on the already applied metrics of capacity percentage change and average absolute capacity percentage change.Citation: Lazaropoulos, A. (2019). Enhancing the Statistical Hybrid Model Performance in Overhead and Underground Medium Voltage Broadband over Power Lines Channels by Adopting Empirical Channel Attenuation Statistical Distribution. Trends in Renewable Energy, 5(2), 181-217. doi:http://dx.doi.org/10.17737/tre.2019.5.2.009
Virtual Indicative Broadband over Power Lines Topologies for Respective Subclasses by Adjusting Channel Attenuation Statistical Distribution Parameters of Statistical Hybrid Models (Class Maps) - Part 1: Theory
Get PDFBased on a set of indicative overhead and underground medium voltage broadband over power lines (OV and UN MV BPL) topologies, initial statistical hybrid model (iSHM) and modified statistical hybrid model (mSHM) are statistical channel models suitable for the distribution BPL networks. Both iSHM and mSHM statistically process channel attenuation and capacity values of assumed indicative OV and UN MV BPL topologies by exploiting channel attenuation statistical distributions (CASDs). iSHM exploits a set of well-known CASDs (i.e., Gaussian, Lognormal, Wald, Weibull and Gumbel CASDs) while mSHM exploits the Empirical CASD. Each indicative OV and UN MV BPL topology acts as the representative one of a respective OV and UN MV BPL topology class (i.e., rural, suburban, urban and aggravated urban class) that consists of a number of respective statistically equivalent OV and UN MV BPL topologies. The contribution of this paper is the theoretical framework presentation of the creation of new virtual indicative OV and UN MV BPL topologies by appropriately adjusting the parameters of iSHM and mSHM CASDs. These new virtual indicative OV and UN MV BPL topologies will enrich the respective today's OV and UN MV BPL topology classes with respective OV and UN MV BPL topology subclasses while each subclass will be enriched by a number of respective statistically equivalent OV and UN MV BPL topologies. The procedure of defining new virtual distribution BPL topologies by applying iSHM and mSHM will allow a better capacity study of OV and UN MV BPL topology classes. Apart from the definition procedure of the virtual indicative OV MV and UN MV BPL topologies and their respective virtual subclasses by adjusting CASD parameters of iSHM and mSHM, the contribution of this paper is the class map that analytically describes the taxonomy of distribution BPL topology classes and subclasses.Citation: Lazaropoulos, A. (2019). Virtual Indicative Broadband over Power Lines Topologies for Respective Subclasses by Adjusting Channel Attenuation Statistical Distribution Parameters of Statistical Hybrid Models (Class Maps) - Part 1: Theory. Trends in Renewable Energy, 5(3), 237-257. doi:http://dx.doi.org/10.17737/tre.2019.5.3.009
Virtual Indicative Broadband over Power Lines Topologies for Respective Subclasses by Adjusting Channel Attenuation Statistical Distribution Parameters of Statistical Hybrid Models (Class Maps) - Part 2: Numerical Results for the Overhead and Underground Medium-Voltage Power Grids
Get PDFWith reference to the initial statistical hybrid model (iSHM) and modified statistical hybrid model (mSHM), the theory of the definition procedure of new virtual indicative distribution BPL topologies by appropriately adjusting the channel attenuation statistical distributions (CASDs) parameters of iSHM and mSHM has been presented in [1]. In this paper, the results of the definition procedure for the OV and UN MV BPL networks are first presented through the prism of the proposed class maps of iSHM and mSHM.Citation: Lazaropoulos, A. (2019). Virtual Indicative Broadband over Power Lines Topologies for Respective Subclasses by Adjusting Channel Attenuation Statistical Distribution Parameters of Statistical Hybrid Models (Class Maps) - Part 2: Numerical Results for the Overhead and Underground Medium-Voltage Power Grids. Trends in Renewable Energy, 5(3), 258-281. doi:http://dx.doi.org/10.17737/tre.2019.5.3.0010
IoT Based Smart Solar Flower Water Pump System
Get PDFThe electric demand of the countries is increasing day by day and the available resources are quite insufficient to fulfill this demand. The reasons are that the conventional energy resources are diminishing and available with finite sources. Due to these reasons, the solar power is one of the promising alternatives that is easily available, pollution free and having higher operating life. The solar system also provides higher operating efficiency for the load, and the cost of the solar panel is minimum. To improve the switching technology used for the power conversion, we presented a smart flower system powered by photovoltaic panels that could supply standalone AC/DC load. In this system, solar panels produce a direct current, which can be converted into AC by the converter and used in home, industrial and agriculture applications. The output of the panels depends on the direction of sun's rays (solar energy), and the solar photovoltaic cell converts the solar energy into useful electrical energy. The aim of this paper is to develop the solar photovoltaic generation system based on a standard power electronics cell for micro industrial, commercial, home as well as agriculture applications. The proposed system is capable to provide protection from wind and rain, thereby the efficiency of the solar panels will increase. The generation of the electricity is more with trackers than stationary counterparts due to direct exposure to sun's rays. This increase can be as much as 25% depending upon the geographic location of the tracking system. The generated output voltage can be used for various purposes, and we used the store energy to run an agriculture water pump by using the internet of things (IoT). Citation: Band, B. H., and Ingole, A. D. (2019). IoT Based Smart Solar Flower Water Pump System. Trends in Renewable Energy, 5, 229-236. DOI: 10.17737/tre.2019.5.3.009
Green Refining of Waste Lubricating Oil: A China Perspective
Get PDFPresently, many regeneration processes of waste lubricating oil, such as catalytic hydrogenation, are available. However, some of these processes are highly costly and not suitable for Chinese economic conditions, and some may produce contaminated impurities such as acid slag, which cannot meet environmental protection requirements. This study aims to develop a green process for the regeneration of waste lubricating oil into a base oil, which should meet the requirements of green chemistry, have the characteristics of simple operation, low cost, less pollution and high recovery rate, and turn wastes into renewable resources. The new process developed via this research has three stages. First, mechanical and large particle impurities in the waste lubricating oil were removed by pretreatment. Second, most of the colloid and asphaltene were removed by thermal extraction and sedimentation. Finally, the activated bleaching earth was used to further purify the waste lubricating oil. The performance evaluation of the finally obtained lubricating base oil conformed to the standard of the HVI-100 lubricating oil. The total recovery rate of the process was about 63.5%.Citation:Â Wu, J., Li, B., Wang, W., Yang, S., Liu, P., Yang, C., and Ding, Y. (2019). Green Refining of Waste Lubricating Oil: A China Perspective. Trends in Renewable Energy, 5, 165-180. DOI: 10.17737/tre.2019.5.2.008
Impact of Sunshine Duration and Clearness Index on Diffuse Solar Radiation Estimation in Mountainous Climate
Get PDFIn this paper, measured data of solar radiation was applied to develop forty-three (43) empirical models for estimation of monthly average diffuse solar radiation using clearness index, sunshine duration and a combination of them as predictors. The data covered a period of two years from May 2015 to April 2017 and was measured at Mehran University of Engineering and Technology, Hyderabad, Pakistan. Through a comprehensive statistical performance analysis, 43 dimensional models developed were tested for constructing the most accurate regression model to predict the monthly mean daily diffuse solar radiation in Hyderabad, Pakistan. On the whole, the model 42- a hybrid of sunshine duration and clearness index predictors of diffuse fraction outperformed the remaining models proposed in this study. The best model (model 42) was then compared with 5 models and 5 measured data of diffuse solar radiation available in the literature and the NASA database by applying statistical indicators such as MBE, MPE, RMSE, RRMSE, R2 and GPI. Through the analysis, the hybrid of sunshine duration and clearness index predictors of diffuse fraction model (model 42) was selected as the most appropriate model. The study concluded that the proposed hybrid model can serve as a baseline for the design of photovoltaic systems and estimate the monthly mean daily diffuse solar radiation on the horizontal surface for Hyderabad, Pakistan and other locations with similar local climate conditions.Citation: Nwokolo, S., & Otse, C. (2019). Impact of Sunshine Duration and Clearness Index on Diffuse Solar Radiation Estimation in Mountainous Climate. Trends in Renewable Energy, 5(3), 307-332. doi:http://dx.doi.org/10.17737/tre.2019.5.3.0010
Broadband Performance Metrics and Regression Approximations of the New Coupling Schemes for Distribution Broadband over Power Lines (BPL) Networks
Get PDFThis paper assesses the broadband performance of overhead (OV) and underground (UN) low-voltage (LV) and medium-voltage (MV) broadband over power lines (BPL) networks when the new refined Coupling Scheme module (CS2 module) is adopted. The broadband performance of distribution BPL networks is assessed in terms of their Average Channel Gain (ACG), Root-Mean-Square Delay-Spread (RMS-DS), Coherence Bandwidth (CB) and Spectral Efficiency (SE). Also, corresponding regression approximations (i.e., UN1, UN2 and UN3 approaches) are given in the examined BPL frequency range. The aforementioned broadband performance metrics of the application of CS2 module are compared against the relative ones of the vintage CS1 module and of MIMO channels. The analysis and relevant numerical results outline: (i) the important improvement of the aforementioned performance metrics and regression approximations when CS2 module is applied in distribution BPL networks instead of CS1 module; and (ii) the universal role of UN1, UN2 and UN3 approaches for describing coupling scheme channels and MIMO ones.Citation: Lazaropoulos, A. (2018). Broadband Performance Metrics and Regression Approximations of the New Coupling Schemes for Distribution Broadband over Power Lines (BPL) Networks.Trends in Renewable Energy, 4(1), 43-73. doi:http://dx.doi.org/10.17737/tre.2018.4.1.005