Journal of Renewable Energy http://www.hindawi.com The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. An Analytical Model for Optimizing the Combination of Energy Sources in a Single Power Transmission Network Tue, 18 Nov 2014 07:50:01 +0000 http://www.hindawi.com/journals/jre/2014/143736/ The increasing amount of renewable energy currently being added to distribution networks presents new challenges and opportunities to system operators. This situation further complicates the operators’ tasks in dealing with changing net loads and balancing. The current work provides an analytical model to assist systems operators in stabilizing power generation and lowering total costs, through optimization of choices in the combination of programmable fossil sources and nonprogrammable renewable sources. The study first examines the various programmable and renewable energy sources that appear broadly suitable and economically appealing for combination. Next we identify the most important factors determining the potential integration of the sources in the system. Based on this introductory information we then develop the model for the selection of the appropriate mix of sources to achieve stable production. In developing the model we define indicators to evaluate and select the best configurations of the sources included in a particular combination. Next we apply the model to a specific case study and finally reexamine the interdependencies among all the variables of the model, to provide a better understanding of its dynamics and results. Massimo de Falco and Nicola Mastrandrea Copyright © 2014 Massimo de Falco and Nicola Mastrandrea. All rights reserved. Inherent Difference in Saliency for Generators with Different PM Materials Tue, 11 Nov 2014 09:15:09 +0000 http://www.hindawi.com/journals/jre/2014/567896/ The inherent differences between salient and nonsalient electrical machines are evaluated for two permanent magnet generators with different configurations. The neodymium based (NdFeB) permanent magnets (PMs) in a generator are substituted with ferrite magnets and the characteristics of the NdFeB generator and the ferrite generator are compared through FEM simulations. The NdFeB generator is a nonsalient generator, whereas the ferrite machine is a salient-pole generator, with small saliency. The two generators have almost identical properties at rated load operation. However, at overload the behaviour differs between the two generators. The salient-pole, ferrite generator has lower maximum torque than the NdFeB generator and a larger voltage drop at high current. It is concluded that, for applications where overload capability is important, saliency must be considered and the generator design adapted according to the behaviour at overload operation. Furthermore, if the maximum torque is the design criteria, additional PM mass will be required for the salient-pole machine. Sandra Eriksson Copyright © 2014 Sandra Eriksson. All rights reserved. Computational Actuator Disc Models for Wind and Tidal Applications Wed, 29 Oct 2014 00:00:00 +0000 http://www.hindawi.com/journals/jre/2014/172461/ This paper details a computational fluid dynamic (CFD) study of a constantly loaded actuator disc model featuring different boundary conditions; these boundary conditions were defined to represent a channel and a duct flow. The simulations were carried out using the commercially available CFD software ANSYS-CFX. The data produced were compared to the one-dimensional (1D) momentum equation as well as previous numerical and experimental studies featuring porous discs in a channel flow. The actuator disc was modelled as a momentum loss using a resistance coefficient related to the thrust coefficient (). The model showed good agreement with the 1D momentum theory in terms of the velocity and pressure profiles. Less agreement was demonstrated when compared to previous numerical and empirical data in terms of velocity and turbulence characteristics in the far field. These models predicted a far larger velocity deficit and a turbulence peak further downstream. This study therefore demonstrates the usefulness of the duct boundary condition (for computational ease) for representing open channel flow when simulating far field effects as well as the importance of turbulence definition at the inlet. B. Johnson, J. Francis, J. Howe, and J. Whitty Copyright © 2014 B. Johnson et al. All rights reserved. Study on Effect of Number of Transparent Covers and Refractive Index on Performance of Solar Water Heater Mon, 01 Sep 2014 07:46:03 +0000 http://www.hindawi.com/journals/jre/2014/757618/ Liquid flat plate collector (solar flat plate collector) is one of the important applications in solar thermal system. The development in solar photovoltaic is an emerging challenge for the solar thermal system. In the current work an attempt has been made to optimize the number of transparent covers and refractive index to improve the optical efficiency and thermal efficiency for the collector. Performance of the liquid flat plate collector at VIT University Vellore has been simulated numerically for January 21st at an interval of half an hour with different numbers of transparent covers (0–3) and different refractive index values ranging from 1.1 to 1.7. The formulation and solutions are developed with simple software Microsoft Office Excel to result the performance characteristics. The result shows that the efficiency of the flat plate collector increases with an increase in number of covers and decreases after an optimum number of covers. It also decreases with an increase in refractive index. The combination of optimum number (two) and lower refractive index (1.1) results improved useful heat. B. Kalidasan and T. Srinivas Copyright © 2014 B. Kalidasan and T. Srinivas. All rights reserved. Solar Water Heating as a Potential Source for Inland Norway Energy Mix Mon, 04 Aug 2014 08:20:14 +0000 http://www.hindawi.com/journals/jre/2014/968320/ The aim of this paper is to assess solar potential and investigate the possibility of using solar water heating for residential application in Inland Norway. Solar potential based on observation and satellite-derived data for four typical populous locations has been assessed and used to estimate energy yield using two types of solar collectors for a technoeconomic performance comparison. Based on the results, solar energy use for water heating is competitive and viable even in low solar potential areas. In this study it was shown that a typical tubular collector in Inland Norway could supply 62% of annual water heating energy demand for a single residential household, while glazed flat plates of the same size were able to supply 48%. For a given energy demand in Inland Norway, tubular collectors are preferred to flat plate collectors for performance and cost reasons. This was shown by break-even capital cost for a series of collector specifications. Deployment of solar water heating in all detached dwellings in Inland could have the potential to save 182 GWh of electrical energy, equivalent to a reduction of 15,690 tonnes of oil energy and 48.6 kt emissions, and contributes greatly to Norway 67.5% renewable share target by 2020. Dejene Assefa Hagos, Alemayehu Gebremedhin, and Björn Zethraeus Copyright © 2014 Dejene Assefa Hagos et al. All rights reserved. Energy Efficient Hybrid Dual Axis Solar Tracking System Tue, 08 Jul 2014 09:20:47 +0000 http://www.hindawi.com/journals/jre/2014/629717/ This paper describes the design and implementation of an energy efficient solar tracking system from a normal mechanical single axis to a hybrid dual axis. For optimizing the solar tracking mechanism electromechanical systems were evolved through implementation of different evolutional algorithms and methodologies. To present the tracker, a hybrid dual-axis solar tracking system is designed, built, and tested based on both the solar map and light sensor based continuous tracking mechanism. These light sensors also compare the darkness and cloudy and sunny conditions assisting daily tracking. The designed tracker can track sun’s apparent position at different months and seasons; thereby the electrical controlling device requires a real time clock device for guiding the tracking system in seeking solar position for the seasonal motion. So the combination of both of these tracking mechanisms made the designed tracker a hybrid one. The power gain and system power consumption are compared with a static and continuous dual axis solar tracking system. It is found that power gain of hybrid dual axis solar tracking system is almost equal to continuous dual axis solar tracking system, whereas the power saved in system operation by the hybrid tracker is 44.44% compared to the continuous tracking system. Rashid Ahammed Ferdaus, Mahir Asif Mohammed, Sanzidur Rahman, Sayedus Salehin, and Mohammad Abdul Mannan Copyright © 2014 Rashid Ahammed Ferdaus et al. All rights reserved. Satisfying the Energy Demand of a Rural Area by Considering the Investment on Renewable Energy Alternatives and Depreciation Costs Sun, 29 Jun 2014 12:48:13 +0000 http://www.hindawi.com/journals/jre/2014/907592/ In this paper, a fuzzy multiobjective model which chooses the best mix of renewable energy options and determines the optimal amount of energy to be transferred from each resource to each end use is proposed. The depreciation of equipment along with time value of money has been taken into account in the first objective function while the second and the third objective functions minimize the greenhouse gas emissions and water consumption, respectively. Also, this study is one of the pioneer works that has considered demand-side management (DSM) as a competitive option against supply-side alternatives for making apt energy planning decisions. Moreover, the intrinsic uncertainty of demand parameter is considered and modeled by fuzzy numbers. To convert the proposed fuzzy multiobjective formulation to a crisp single-objective formulation the well-known fuzzy goal programming approach together with Jimenez defuzzifying technique is employed. The model is validated through setting up a diversity of datasets whose data were mostly derived from the literature. The obtained results show that DSM programs have greatly contributed to cost reductions in the network. Also, it is concluded that the model is capable of solving even large-scaled instances of problems in negligible central processing unit (CPU) times using Lingo 8.0 software. Masoud Rabbani, Yaser Rahimi, Seyed Mahmood Kazemi, and Mehran Samavati Copyright © 2014 Masoud Rabbani et al. All rights reserved. Assessment of the Potential of Biomass Gasification for Electricity Generation in Bangladesh Thu, 12 Jun 2014 00:00:00 +0000 http://www.hindawi.com/journals/jre/2014/429518/ Bangladesh is an agriculture based country where more than 65 percent of the people live in rural areas and over 70% of total primary energy consumption is covered by biomass, mainly agricultural waste and wood. Only about 6% of the entire population has access to natural gas, primarily in urban areas. Electricity production in Bangladesh largely depends on fossil fuel whose reserve is now under threat and the government is now focusing on the alternating sources to harness electricity to meet the continuous increasing demand. To reduce the dependency on fossil fuels, biomass to electricity could play a vital role in this regard. This paper explores the biomass based power generation potential of Bangladesh through gasification technology—an efficient thermochemical process for distributed power generation. It has been estimated that the total power generation from the agricultural residue is about 1178 MWe. Among them, the generation potential from rice husk, and bagasses is 1010 MWe, and 50 MWe, respectively. On the other hand, wheat straw, jute stalks, maize residues, lentil straw, and coconut shell are also the promising biomass resources for power generation which counted around 118 MWe. The forest residue and municipal solid waste could also contribute to the total power generation 250 MWe and 100 MWe, respectively. Barun Kumar Das and S. M. Najmul Hoque Copyright © 2014 Barun Kumar Das and S. M. Najmul Hoque. All rights reserved. Comparison and Optimization of Neural Networks and Network Ensembles for Gap Filling of Wind Energy Data Mon, 26 May 2014 05:39:49 +0000 http://www.hindawi.com/journals/jre/2014/986830/ Wind turbines play an important role in providing electrical energy for an ever-growing demand. Due to climate change driven by anthropogenic emissions of greenhouse gases, the exploration and use of sustainable energy sources is essential with wind energy covering a significant portion. Data of existing wind turbines is needed to reduce the uncertainty of model predictions of future energy yields for planned wind farms. Due to maintenance routines and technical issues, data gaps of reference wind parks are unavoidable. Here, we present real-world case studies using multilayer perceptron networks and radial basis function networks to reproduce electrical energy outputs of wind turbines at 3 different locations in Germany covering a range of landscapes with varying topographic complexity. The results show that the energy output values of the turbines could be modeled with high correlations ranging from 0.90 to 0.99. In complex terrain, the RBF networks outperformed the MLP networks. In addition, rare extreme values were better captured by the RBF networks in most cases. By using wind meteorological variables and operating data recorded by the wind turbines in addition to the daily energy output values, the error could be further reduced to more than 20%. Andres Schmidt and Maya Suchaneck Copyright © 2014 Andres Schmidt and Maya Suchaneck. All rights reserved. Feasibility and Optimal Design of a Stand-Alone Photovoltaic Energy System for the Orphanage Wed, 30 Apr 2014 08:28:14 +0000 http://www.hindawi.com/journals/jre/2014/379729/ Access to electricity can have a positive psychological impact through a lessening of the sense of exclusion, and vulnerability often felt by the orphanages. This paper presented the simulation and optimization study of a stand-alone photovoltaic power system that produced the desired power needs of an orphanage. Solar resources for the design of the system were obtained from the National Aeronautics and Space Administration (NASA) Surface Meteorology and Solar Energy website at a location of 6°51′N latitude and 7°35′E longitude, with annual average solar radiation of 4.92 kWh/m2/d. This study is based on modeling, simulation, and optimization of energy system in the orphanage. The patterns of load consumption within the orphanage were studied and suitably modeled for optimization. Hybrid Optimization Model for Electric Renewables (HOMER) software was used to analyze and design the proposed stand-alone photovoltaic power system model. The model was designed to provide an optimal system configuration based on an hour-by-hour data for energy availability and demands. A detailed design, description, and expected performance of the system were presented in this paper. Vincent Anayochukwu Ani Copyright © 2014 Vincent Anayochukwu Ani. All rights reserved. Microalgae as a Renewable Source of Energy: A Niche Opportunity Thu, 24 Apr 2014 10:05:34 +0000 http://www.hindawi.com/journals/jre/2014/430203/ Algae are believed to be a good source of renewable energy because of its rapid growth rate and its ability to be cultivated in waste water or waste land. Several companies and government agencies are making efforts to reduce capital cost and operating costs and make algae fuel production commercially viable. Algae are the fastest growing plant and theoretically have the potential to produce more oil or biomass per acre when compared to other crops and plants. However, the energy efficiency ratio and carbon and water footprint for algal based biofuels still need to be evaluated in order to fully understand the environmental impact of algal derived biofuels. Simon Jegan Porphy Jegathese and Mohammed Farid Copyright © 2014 Simon Jegan Porphy Jegathese and Mohammed Farid. All rights reserved. Combustion and Emission Characteristics of Variable Compression Ignition Engine Fueled with Jatropha curcas Ethyl Ester Blends at Different Compression Ratio Wed, 16 Apr 2014 16:20:26 +0000 http://www.hindawi.com/journals/jre/2014/872923/ Engine performance and emission characteristics of unmodified biodiesel fueled diesel engines are highly influenced by their ignition and combustion behavior. In this study, emission and combustion characteristics were studied when the engine operated using the different blends (B10, B20, B30, and B40) and normal diesel fuel (B0) as well as when varying the compression ratio from 16.5 : 1 to 17.5 : 1 to 18.5 : 1. The change of compression ratio from 16.5 : 1 to 18.5 : 1 resulted in 27.1%, 27.29%, 26.38%, 28.48%, and 34.68% increase in cylinder pressure for the blends B0, B10, B20, B30, and B40, respectively, at 75% of rated load conditions. Higher peak heat release rate increased by 23.19%, 14.03%, 26.32%, 21.87%, and 25.53% for the blends B0, B10, B20, B30, and B40, respectively, at 75% of rated load conditions, when compression ratio was increased from16.5 : 1 to 18.5 : 1. The delay period decreased by 21.26%, CO emission reduced by 14.28%, and emission increased by 22.84% for B40 blends at 75% of rated load conditions, when compression ratio was increased from 16.5 : 1 to 18.5 : 1. It is concluded that Jatropha oil ester can be used as fuel in diesel engine by blending it with diesel fuel. Rajneesh Kumar and Anoop Kumar Dixit Copyright © 2014 Rajneesh Kumar and Anoop Kumar Dixit. All rights reserved. Design of an Energy System Based on Photovoltaic Thermal Collectors in the South of Algeria Sun, 30 Mar 2014 12:46:46 +0000 http://www.hindawi.com/journals/jre/2014/824529/ The objective of this work is the design of a new energy system where the energy source will be provided by solar photovoltaic thermal (PV/T) hybrid collectors. This system will be applied to a habitation in the region of Ghardaïa in the south of Algeria. The cold water reaches the thermal storage tank and then will be heated by the hybrid collector. The hot water will be used directly as sanitary water. The electric power produced by the hybrid collector will be used to charge the battery and will be delivered to the load (electrical appliances, lamps, etc.). Two types of loads are considered: a DC load and the other alternating current. The fans located adjacent to the radiators supplied with hot water will provide warm air to the house in winter. K. Touafek, A. Khelifa, M. Adouane, and H. Haloui Copyright © 2014 K. Touafek et al. All rights reserved. Design and Modelling of Water Chilling Production System by the Combined Effects of Evaporation and Night Sky Radiation Sun, 02 Mar 2014 00:00:00 +0000 http://www.hindawi.com/journals/jre/2014/624502/ The design and mathematical modelling of thermal radiator panel to be used primarily to measure night sky radiation wet coated surface is presented in this paper. The panel consists of an upper dry surface coated aluminium sheet laminated to an ethylene vinyl acetate foam backing block as an insulation. Water is sprayed onto the surface of the panel so that an evaporative cooling effect is gained in addition to the radiation effect; the surface of a panel then is wetted in order to study and measure the night sky radiation from the panel wet surface. In this case, the measuring water is circulated over the upper face of this panel during night time. Initial TRNSYS simulations for the performance of the system are presented and it is planned to use the panel as calibrated instruments for discriminating between the cooling effects of night sky radiation and evaporation. Ahmed Y. Taha Al-Zubaydi and W. John Dartnall Copyright © 2014 Ahmed Y. Taha Al-Zubaydi and W. John Dartnall. All rights reserved. Determining Balıkesir’s Energy Potential Using a Regression Analysis Computer Program Tue, 25 Feb 2014 08:39:42 +0000 http://www.hindawi.com/journals/jre/2014/975403/ Solar power and wind energy are used concurrently during specific periods, while at other times only the more efficient is used, and hybrid systems make this possible. When establishing a hybrid system, the extent to which these two energy sources support each other needs to be taken into account. This paper is a study of the effects of wind speed, insolation levels, and the meteorological parameters of temperature and humidity on the energy potential in Balıkesir, in the Marmara region of Turkey. The relationship between the parameters was studied using a multiple linear regression method. Using a designed-for-purpose computer program, two different regression equations were derived, with wind speed being the dependent variable in the first and insolation levels in the second. The regression equations yielded accurate results. The computer program allowed for the rapid calculation of different acceptance rates. The results of the statistical analysis proved the reliability of the equations. An estimate of identified meteorological parameters and unknown parameters could be produced with a specified precision by using the regression analysis method. The regression equations also worked for the evaluation of energy potential. Bedri Yüksel and Ergun Ateş Copyright © 2014 Bedri Yüksel and Ergun Ateş. All rights reserved. Magnetic Biofilm Carriers: The Use of Novel Magnetic Foam Glass Particles in Anaerobic Digestion of Sugar Beet Silage Mon, 24 Feb 2014 13:32:20 +0000 http://www.hindawi.com/journals/jre/2014/208718/ The use of recently developed magnetic foam glass particles for immobilization of microbial biomass was tested. The effect of the particles was illustrated at the production of biogas from sugar beet silage as the sole substrate. Lab-scale fermentation experiments were conducted using a mesophilic completely stirred tank reactor and a magnetic separator. Microscopic analysis revealed biofilm coverage of 50–60% on the surface of the particles within 110 days. It was possible to recover 76.3% of the particles from fermentation effluent by means of a separation procedure based on magnetic forces. Comparing a particle charged reactor with a control reactor showed a small performance gain. The methane rate was increased from to  L L−1 d−1 and the methane yield was increased from to  L g−1 (volatile solids) at an organic loading rate of  g L−1 d−1 (volatile solids). Maximum methane rates of 1.42 L L−1 d−1 at an organic loading rate of 4.60 g (volatile solids) L−1 d−1 (reactor including magnetic particles) and 1.34 L L−1 d−1 at 3.73 g L−1 d−1 (control reactor) were achieved. Based on the results, it can be concluded that the use of magnetic particles could be an attractive option for the optimization of biogas production. Patrice Ramm, Carsten Jost, Elisabeth Neitmann, Ulrich Sohling, Oliver Menhorn, Karl Weinberger, Jan Mumme, and Bernd Linke Copyright © 2014 Patrice Ramm et al. All rights reserved. A Review of the Wood Pellet Value Chain, Modern Value/Supply Chain Management Approaches, and Value/Supply Chain Models Mon, 27 Jan 2014 07:13:23 +0000 http://www.hindawi.com/journals/jre/2014/654158/ We reviewed 153 peer-reviewed sources to provide identification of modern supply chain management techniques and exploration of supply chain modeling, to offer decision support to managers. Ultimately, the review is intended to assist member-companies of supply chains, mainly producers, improve their current management approaches, by directing them to studies that may be suitable for direct application to their supply chains and value chains for improved efficiency and profitability. We found that information on supply chain management and modeling techniques in general is available. However, few Canadian-based published studies exist regarding a demand-driven modeling approach to value/supply chain management for wood pellet production. Only three papers were found specifically on wood pellet value chain analysis. We propose that more studies should be carried out on the value chain of wood pellet manufacturing, as well as demand-driven management and modeling approaches with improved demand forecasting methods. Natalie M. Hughes, Chander Shahi, and Reino Pulkki Copyright © 2014 Natalie M. Hughes et al. All rights reserved. FEMAN: Fuzzy-Based Energy Management System for Green Houses Using Hybrid Grid Solar Power Sun, 01 Sep 2013 13:28:22 +0000 http://www.hindawi.com/journals/jre/2013/785636/ The United Nations has designated the year 2012 as the international year of sustainable energy. Today, we are seeing a rise in global awareness of energy consumption and environmental problems. Many nations have launched different programs to reduce the energy consumption in residential and commercial buildings to seek lower-carbon energy solutions. We are talking about the future green and smart houses. The subject of smart/green houses is not one of “why,” but rather “how,” specifically: “how making the future house more energy efficient.” The use of the renewable energy, the technology and the services could help us to answer this question. Intelligent home energy management is an approach to build centralized systems that deliver application functionality as services to end-consumer applications. The objective of this work is to develop a smart and robust controller for house energy consumption with maximizing the use of solar energy and reducing the impact on the power grid while satisfying the energy demand of house appliances. We proposed a fuzzy-based energy management controller in order to reduce the consumed energy of the building while respecting a fixed comfort. Abdellah Chehri and Hussein T. Mouftah Copyright © 2013 Abdellah Chehri and Hussein T. Mouftah. All rights reserved. Modeling and Characteristic Analysis of a Solar Parabolic Trough System: Thermal Oil as the Heat Transfer Fluid Sun, 18 Aug 2013 09:42:28 +0000 http://www.hindawi.com/journals/jre/2013/389514/ The thermal oil is applied as the heat transfer fluid in a solar parabolic trough collector system. Firstly, the system dynamic model was established and validated by the real operating data in typical summer and spring days in references. Secondly, the alteration characteristics of different solar radiation, inlet water temperature and flow rate, and collectors’ area and length are analyzed and compared with the normal working condition. The model can be used for studying, system designing, and better understanding of the performance of parabolic trough systems. Zhai Rongrong, Yang Yongping, Yan Qin, and Zhu Yong Copyright © 2013 Zhai Rongrong et al. All rights reserved. The Effectiveness of Feature Selection Method in Solar Power Prediction Tue, 06 Aug 2013 08:27:55 +0000 http://www.hindawi.com/journals/jre/2013/952613/ This paper empirically shows that the effect of applying selected feature subsets on machine learning techniques significantly improves the accuracy for solar power prediction. Experiments are performed using five well-known wrapper feature selection methods to obtain the solar power prediction accuracy of machine learning techniques with selected feature subsets. For all the experiments, the machine learning techniques, namely, least median square (LMS), multilayer perceptron (MLP), and support vector machine (SVM), are used. Afterwards, these results are compared with the solar power prediction accuracy of those same machine leaning techniques (i.e., LMS, MLP, and SVM) but without applying feature selection methods (WAFS). Experiments are carried out using reliable and real life historical meteorological data. The comparison between the results clearly shows that LMS, MLP, and SVM provide better prediction accuracy (i.e., reduced MAE and MASE) with selected feature subsets than without selected feature subsets. Experimental results of this paper facilitate to make a concrete verdict that providing more attention and effort towards the feature subset selection aspect (e.g., selected feature subsets on prediction accuracy which is investigated in this paper) can significantly contribute to improve the accuracy of solar power prediction. Md Rahat Hossain, Amanullah Maung Than Oo, and A. B. M. Shawkat Ali Copyright © 2013 Md Rahat Hossain et al. All rights reserved. Propagation of Shock on NREL Phase VI Wind Turbine Airfoil under Compressible Flow Sun, 28 Jul 2013 08:30:57 +0000 http://www.hindawi.com/journals/jre/2013/653103/ The work is focused on numeric analysis of compressible flow around National Renewable Energy Laboratory (NREL) phase VI wind turbine blade airfoil S809. Although wind turbine airfoils are low Reynolds number airfoils, a reasonable investigation of compressible flow under extreme condition might be helpful. A subsonic flow (mach no. ) has been considered for this analysis and the impacts of this flow under seven different angles of attack have been determined. The results show that shock takes place just after the mid span at the top surface and just before the mid span at the bottom surface at zero angle of attack. Slowly the shock waves translate their positions as angle of attack increases. A relative translation of the shock waves in upper and lower face of the airfoil are presented. Variation of Turbulent viscosity ratio and surface Y+ have also been determined. A k-ω SST turbulent model is considered and the commercial CFD code ANSYS FLUENT is used to find the pressure coefficient (Cp) as well as the lift (CL) and drag coefficients (CD). A graphical comparison of shock propagation has been shown with different angle of attack. Flow separation and stream function are also determined. Mohammad A. Hossain, Ziaul Huque, and Raghava R. Kammalapati Copyright © 2013 Mohammad A. Hossain et al. All rights reserved. Evaluation of Harmonic Content from a Tap Transformer Based Grid Connection System for Wind Power Sun, 21 Jul 2013 10:48:38 +0000 http://www.hindawi.com/journals/jre/2013/190573/ Simulations done in MATLAB/Simulink together with experiments conducted at the Ångströms laboratory are used to evaluate and discuss the total harmonic distortion (THD) and total demand distortion (TDD) of a tap transformer based grid connection system. The grid connection topology can be used with different turbine and generator topologies and is here applied on a vertical axis wind turbine (VAWT) with a permanent magnet synchronous generator (PMSG) and its operational scheme. The full variable-speed wind conversion system consists of a diode rectifier, DC link, IGBT inverter, LCL-filter, and tap transformer. The full variable-speed operation is enabled by the use of the different step-up ratios of the tap transformer. In the laboratory study, a full experimental setup of the system was used, a clone of the on-site PMSG driven by a motor was used, and the grid was replaced with a resistive load. With a resistive load, grid harmonics and possible unbalances are removed. The results show a TDD and THD below 5% for the full operating range and harmonic values within the limits set up by IEEE-519. Furthermore, a change in tap, going to a lower step-up ratio, results in a reduction in both THD and TDD for the same output power. S. Apelfröjd and S. Eriksson Copyright © 2013 S. Apelfröjd and S. Eriksson. All rights reserved. Evaluation of Potential Geographic Distribution for Large-Scale Photovoltaic System in Suburbs of China Sun, 21 Jul 2013 09:24:00 +0000 http://www.hindawi.com/journals/jre/2013/106063/ Since China is the largest CO2 emitting country in the world, photovoltaic (PV) systems are expected to be widely installed to reduce CO2 emission. In general, available area for PV installation depends on urban area due to differences in land use and slope. Amount of electricity generated by a PV system also depends on urban area because of differences in solar irradiation and ambient temperature. The aim of this study is to evaluate the installation of large-scale PV systems in suburbs of China, taking these differences into consideration. We have used a geographic information system (GIS) to evaluate amounts of installation capacity of large-scale PV systems, electricity generated, and CO2 emission reduction by the installation capacity of large-scale PV systems in suburbs of Liaoning, Shanghai, Anhui, and Guangdong. In Liaoning, the amount of CO2 emission reduction by the installation capacity of large-scale PV systems was estimated to be the largest, 3,058 kt-CO2/yr, due to its larger amount of the installation capacity, 2439.4 MW, than the amount of the installation capacity in other regions. Masashi Kawase, Keiichi Okajima, and Yohji Uchiyama Copyright © 2013 Masashi Kawase et al. All rights reserved. Optimization of the Energy Output of Osmotic Power Plants Tue, 16 Jul 2013 12:57:58 +0000 http://www.hindawi.com/journals/jre/2013/496768/ On the way to a completely renewable energy supply, additional alternatives to hydroelectric, wind, and solar power have to be investigated. Osmotic power is such an alternative with a theoretical global annual potential of up to 14400 TWh (70% of the global electricity consumption of 2008) per year. It utilizes the phenomenon that upon the mixing of fresh water and oceanic salt water (e.g., at a river mouth), around 2.88 MJ of energy per 1 m3 of fresh water is released. Here, we describe a new approach to derive operational parameter settings for osmotic power plants using a pressure exchanger for optimal performance, either with respect to maximum generated power or maximum extracted energy. Up to now, only power optimization is discussed in the literature, but when considering the fresh water supply as a limiting factor, the energy optimization appears as the challenging task. Florian Dinger, Tobias Tröndle, and Ulrich Platt Copyright © 2013 Florian Dinger et al. All rights reserved. Computational Study on the Aerodynamic Performance of Wind Turbine Airfoil Fitted with Coandă Jet Mon, 27 May 2013 12:40:10 +0000 http://www.hindawi.com/journals/jre/2013/839319/ Various methods of flow control for enhanced aerodynamic performance have been developed and applied to enhance and control the behavior of aerodynamic components. The use of Coandă effect for the enhancement of circulation and lift has gained renewed interest, in particular with the progress of CFD. The present work addresses the influence, effectiveness, and configuration of Coandă-jet fitted aerodynamic surface for improving lift and , specifically for S809 airfoil, with a view on its incorporation in the wind turbine. A simple two-dimensional CFD modeling using - turbulence model is utilized to reveal the key elements that could exhibit the desired performance for a series of S809 airfoil configurations. Parametric study performed indicates that the use of Coandă-jet S809 airfoil can only be effective in certain range of trailing edge rounding-off radius, Coandă-jet thickness, and momentum jet size. The location of the Coandă-jet was found to be effective when it is placed close to the trailing edge. The results are compared with experimental data for benchmarking. Three-dimensional configurations are synthesized using certain acceptable assumptions. A trade-off study on the S809 Coandă configured airfoil is needed to judge the optimum configuration of Coandă-jet fitted Wind-Turbine design. H. Djojodihardjo, M. F. Abdul Hamid, A. A. Jaafar, S. Basri, F. I. Romli, F. Mustapha, A. S. Mohd Rafie, and D. L. A. Abdul Majid Copyright © 2013 H. Djojodihardjo et al. All rights reserved. Pretreated Landfill Gas Conversion Process via a Catalytic Membrane Reactor for Renewable Combined Fuel Cell-Power Generation Wed, 08 May 2013 16:02:37 +0000 http://www.hindawi.com/journals/jre/2013/209364/ A new landfill gas-based reforming catalytic processing system for the conversion of gaseous hydrocarbons, such as incoming methane to hydrogen and carbon oxide mixtures, is described and analyzed. The exit synthesis gas (syn-gas) is fed to power effectively high-temperature fuel cells such as SOFC types for combined efficient electricity generation. The current research work is also referred on the description and design aspects of permreactors (permeable reformers) carrying the same type of landfill gas-reforming reactions. Membrane reactors is a new technology that can be applied efficiently in such systems. Membrane reactors seem to perform better than the nonmembrane traditional reactors. The aim of this research includes turnkey system and process development for the landfill-based power generation and fuel cell industries. Also, a discussion of the efficient utilization of landfill and waste type resources for combined green-type/renewable power generation with increased processing capacity and efficiency via fuel cell systems is taking place. Moreover, pollution reduction is an additional design consideration in the current catalytic processors fuel cell cycles. Zoe Ziaka and Savvas Vasileiadis Copyright © 2013 Zoe Ziaka and Savvas Vasileiadis. All rights reserved. Case Study of Integrating an Offshore Wind Farm with Offshore Oil and Gas Platforms and with an Onshore Electrical Grid Mon, 29 Apr 2013 15:01:47 +0000 http://www.hindawi.com/journals/jre/2013/607165/ This research project explored the technical feasibility of utilizing an offshore wind farm as a supplementary power source to several electrical grids of offshore oil and gas platforms and providing surplus power to an onshore grid. Three case studies comprising wind farms rated at 20 MW, 100 MW, and 1000 MW have been studied with the focus on (i) the operation benefits of CO2/NOx emission reduction, (ii) the electrical grid stability, and (iii) the technical implementation feasibility. The proposed 20 MW, 100 MW, and 1000 MW wind farm cases are theoretically feasible in terms of the selected technical criteria, although further detailed design operational studies, and economical analysis are required. Wei He, Kjetil Uhlen, Mahesh Hadiya, Zhe Chen, Gang Shi, and Emilio del Rio Copyright © 2013 Wei He et al. All rights reserved. Performance Evaluation of a Double-Glazed Box-Type Solar Oven with Reflector Sun, 28 Apr 2013 18:06:22 +0000 http://www.hindawi.com/journals/jre/2013/184352/ This research paper describes the performance evaluation of a double-glazed box-type solar oven with reflector fabricated using locally available materials, compressed sawdust with binder; size of the box is 700 mm ×  700 mm × 400 mm and 10 mm thickness. The experimental solar cooker consists of an aluminium absorber plate (1 mm) painted matt black and a double-glazed lid. The bottom and sides are lagged with fibreglass wool insulator, thickness = 50 mm,  W/m°C. The reflector consists of a wooden-framed commercially available specular plane mirror which is sized to form a cover for the box when not being in use. Its thermal performance was tested according to the ASAE International Test procedure and Bureau of Indian Standards (BIS) for testing the thermal performance of box-type solar cooker. Thermal performance experiments were conducted in order to determine the first figure of merit (F1), the second figure of merit (F2) and standard cooking power (Ps). The obtained test results were employed to calculate the two figures of merit (F1, and F2) and the standard cooking power (P50) to be 0.11 Km2w−1, 0.31, and 23.95 W, respectively. Finally, the results illustrated that the cooker has a good reliability for cooking food and boiling water. Joshua Folaranmi Copyright © 2013 Joshua Folaranmi. All rights reserved. Ventilated Double Window for the Preheating of the Ventilation Air Comparison of Its Performance in a Northern and a Southern European Climate Tue, 16 Apr 2013 14:38:23 +0000 http://www.hindawi.com/journals/jre/2013/290865/ Keeping the indoor air quality within the reference levels requires that the polluted indoor air be replaced by fresh air coming from the outside. This paper presents a sensitivity analysis and a series of simulations where the performance of this passive system is studied. The influence of each relevant factor, like the wind, the solar radiation, and the outdoor air temperature, is assessed. Two different local sets of climatic data were chosen, a mild and a cold winter. Jorge S. Carlos and Helena Corvacho Copyright © 2013 Jorge S. Carlos and Helena Corvacho. All rights reserved. Investigation of Energy Storage Systems, Its Advantage and Requirement in Various Locations in Australia Thu, 11 Apr 2013 18:56:00 +0000 http://www.hindawi.com/journals/jre/2013/835309/ Storage minimizes the intermittent nature of renewable sources. Solar and wind are the two fostered source of renewable energy. However, the availability of useful solar radiation and wind speed varies with geographical locations, and also the duration of this energy sources varies with seasonal variation. With the available vast open land and geographical position, Australia has great potential for both solar and wind energies. However, both these sources require energy buffering to support load demand to ensure required power quality. Electricity demand is increasing gradually, and also Australia has target to achieve 20% electricity from renewable sources by 2020. For effective utilization of solar and wind energy potential location of these sources needs to be identified, and effective size of storage needs to be estimated for best utilization according to the load demand. Therefore this paper investigated wind speed and solar radiation data of 210 locations in Australia, identified the potential locations, and estimated required storage in various potential locations to support residential load demand. Advantages of storage were analyzed in terms of loading on distribution transformer and storage support during energy fluctuation from renewable energy. Further analysis showed that storage greatly reduces greenhouse gas emission and reduces overall cost of energy by maximizing the use of solar and wind energies. Mohammad Taufiqul Arif, Amanullah M. T. Oo, and A. B. M. Shawkat Ali Copyright © 2013 Mohammad Taufiqul Arif et al. All rights reserved.