ALBERT

Description: As urbanization continues across the globe, cities face significant challenges and opportunities to grow in ways that reduce carbon emissions while providing high quality of life. An EcoPartnership between the cities of Portland, Oregon, USA and Kunming, China is designed to accelerate the exchange of policies and strategies for low-carbon development. Kunming successfully implemented China's first bus-rapid transit system (BRT); Portland is currently analyzing the feasibility of BRT. Portland relies on an urban growth boundary (UGB) as a key policy to guide growth management; Kunming is evaluating the feasibility of a UGB. Both cities are investing in infrastructure for bicycle networks. Key characteristics of successful collaboration include shared substantive priorities; familiarity with the institutional context and roles of the individuals involved; a good match in the responsibilities of the participating agencies and individuals; interpersonal rapport and trust; and the persistence of the collaboration over time.

Description: This paper investigates a method for optimal control of a point absorbing wave energy converter by considering the constraints on motions and forces in the time domain. The problem is converted to an optimization problem with the cost function being convex quadratic and the constraints being nonlinear. The influence of the constraints on the converter is studied, and the results are compared with uncontrolled cases and established theoretical bounds. Since this method is based on the knowledge of the future sea state or the excitation force, the influence of the prediction horizon is indicated. The resulting performance of the wave energy converter under different regular waves shows that this method leads to a substantial increase in conversion efficiency.

Description: Biomass tar can be used as reducing agent for reduction of iron oxide, and simultaneously iron is a good catalyst for tar cracking. Thus, an iron ore reduction system integrated tar cracking and iron ore reduction was proposed. The influences of raw material characteristics, the equivalence ratio of tar to iron ore fines as well as reduction conditions on the reduction behaviors of iron ore fines were discussed. Also, the co-pyrolysis of mixture of tar and iron ore fines was investigated. The results show that the iron ore reduction using tar is reliable with a high tar cracking efficiency and a high reduction degree. Due to the formation of porous structures, preheated iron ore fines showed an excellent reduction behavior than those without preheating. At the initial stage, iron oxide did not exert any obvious effect on tar destruction, while as reaction temperature raised above 600 °C, a noticeable decline of tar content was observed, which was attributed to the enhanced reduction consumption and catalytic decomposition by the reduced iron. Increasing the ratio of tar to iron ore was favorable for the reduction of iron oxide, while, when the ratio exceeding 0.6, the effect became less notable. The introduction of proper amount of steam can improve tar cracking and further improve iron oxide reduction. At optimum conditions (iron ore fines was first preheated at 400 °C and then mixed with tar according to tar/iron ore fines 0.6, reacted at 900 °C for 30 min under the steam atmosphere with the mass ratio of steam/tar 0.87), the reduced iron product with metallization rate 94.1% was achieved.

Description: Integrating renewable energy into standalone Internal Combustion Generator (ICG) systems is an economical and eco-friendly option. However, previous studies demonstrate the difficulties in replacing the ICGs completely by using Solar PV (SPV) and wind energy with a dispatchable energy storage. This makes it interesting to analyze the limitations in integrating the SPV and wind energy into Hybrid Energy System. A multi criterion analysis is presented in this study, considering Levelized Energy Cost, Loss of Load Probability, and Fuel Consumption varying the scale of the ICG capacity to attain aforementioned objective. Changes in the system design with the integration of the SPV and wind energy were analyzed using Pareto multi-objective optimization considering Renewable Energy Capacity as an objective function. Sensitivity of the ICG capacity on optimum Renewable Energy Technology, role of the ICG in improving system reliability, etc., were subsequently analyzed. The results depict that the ICG capacity notably influence to the balance between wind and SPV capacity. An increase in the ICG capacity does increase the contribution from dispatchable energy source in most of the scenarios. Furthermore, it facilitates to amalgamate highly fluctuating renewable energy sources at a relatively low cost. This makes it inevitable to replace ICG with non-dispatchable renewable energy sources and energy storage.

Description: Photovoltaic (PV) energy is one of the most important renewable energies because it is clean, requires very little maintenance. However, the relatively high costs and low conversion efficiency are still the major challenge to a larger and faster spread of PV systems. Therefore, the maximum power point tracker (MPPT) is essential in a PV system for maximizing the conversion efficiency of the solar array. Because of the nonlinear behavior of the PV systems, various techniques of the MPPT are employed in order to continuously operate the solar array at their MPP, despite the unavoidable changes in solar irradiance and temperature. This paper presents an assessment of five widely used MPPT techniques. These techniques are simulated in Matlab/Simulink environment in order to provide a comparison in terms of sensors required, ease of implementation, efficiency, the dynamic response of the PV system to variations in temperature and irradiance, and their appropriateness for the different applications of PV system. This can be used as a reference for future research related to the PV power generation.

Description: Since launching the PlantBottle™ Packaging program in 2009, The Coca-Cola Company has distributed more than 30 × 10 9 bottles in nearly 40 countries using its current PlantBottle packaging, which is made from up to 30% plant-based materials. It is estimated the use of PlantBottle packaging since launch has helped save the equivalent annual emissions of more than 315 000 metric tons of carbon dioxide. To expand the application of this innovative packaging material, a sustainable feedstock needs to be identified, and a new technology needs to be developed to allow its integration into PlantBottle technology, for using agriculture waste to produce bio-polyethylene terephthalate (bio-PET), and develop an economically viable supply chain of bio-PET in China. These breakthroughs can also be applied beyond packaging and have the potential to help companies around the world reach their own sustainability goals. Using renewable feedstock to produce bio-PET reduces dependence on petro-based resources, mitigates carbon emissions, and promotes sustainable development. Under the China-US EcoPartnership program, The Coca-Cola Company partners with the Yangtze River Delta Circular Economy Institute of Technologyto identify and advance commercial technologies for converting local agricultural residues or wastes (e.g., corn cob and stover) into the base ingredient, mono-ethylene glycol (MEG), for manufacturing polyester resin/fiber. The Coca-Cola Company is developing bio-MEG conversion technology with a technology and implementation partner, and finalizing the technical conversion process for commercial production. Yangtze River Delta Circular Economy Institute of Technology is exploring the related supply chain and feedstock logistics. Any advancement using agricultural wastes today are likely to have continued relevance to this second part of the journey toward realizing sustainably sourced and fully recyclable PET plastic product solutions.

Description: In keeping with the Energy and Environment theme of the EcoPartnership program, the Stony Brook-Tongji collaboration is addressing greenhouse gas emissions from landfills, one of the most critical issues of our time. Tongji is developing a model that can significantly improve the accuracy of emissions estimates, while Stony Brook is perfecting an innovative technology to economically removal impurities and produce a clean fuel for transportation, heating, or electricity generation. The environmental impact of the process being developed under this collaboration versus releasing fugitive gases is noted. By the culmination of this partnership, both sides have developed economical pathways to effectively utilize fugitive gases and commercialized technologies for transportation use and power generation for offering in both countries.

Description: Sustainable development in a quickly urbanizing and resource-constrained world is more essential now than ever before. There is a chance to lock-in high performance for decades to come as vast new construction efforts are pursued throughout China and around the world. Local governments play a critical leadership role in planning and implementing sustainable development measures, but they may face capacity, resource, and stakeholder buy-in constraints. A comprehensive and well-informed approach is the key to unlocking viable long-term solutions that enhance the quality of life for their constituents. International cooperation in this endeavor can be incredibly transformative, as peers are able to share innovative best practices and information. Development priorities often vary and solutions have to be tailored for their unique context, but there are recurrent winning concepts that can be readily parlayed from one locality to another. This paper explores how the International City/County Management Association and China University of Political Science and Law are leveraging the U.S.-China EcoPartnerships program to amplify sustainable development at the local-level in a number of locations throughout both countries.

Description: In July 2014, the Port of Los Angeles (POLA) and the Shanghai Municipal Transportation Commission (SMTC, formerly Port of Shanghai) entered into an EcoPartnership focused on reducing air emissions at both ports by instituting and expanding the use of Shore Power on ocean-going vessels while at berth. In 2004, POLA became the first port in the world to have a container ship plug into shore power through their Alternative Maritime Power™ (AMP™) program. Since then, the shore power plug-in program has expanded to include all container terminals and the cruise terminal at POLA, and significant air emission reductions have occurred as a direct result of those efforts. The EcoPartnership builds upon that experience to support the development of SMTC's capabilities in technology, strategy, and policy development as it relates to shore power. POLA and SMTC developed annual milestones extending through the term of the EcoPartnership agreement with a goal of successfully setting up and implementing a Shore Power program at a Shanghai terminal, including the successful operation of four shore power-ready terminals by 2017. Through their term in the EcoPartnership program, both ports will continue to collaborate and learn from each other on a variety of environmental issues. The potential benefits of the EcoPartnership extend much further. It is envisioned that coordinated development of compatible shore power infrastructure will encourage ship owners to more rapidly convert their fleet to allow ships to plug in, expediting emission reductions at both ports. Additionally, this project will serve as an example that other ports across the globe can use to implement shore power programs at their facilities.

Description: This paper proposes a set of guideline for optimum design of an energy harvester from the vertical motion of small boats and yachts. The device comprises a sprung mass coupled to an electrical generator using a ball screw. The mathematical equations describing the dynamics of the system are derived. The equations are used as a basis for determining the optimum device parameters, namely, its mass, spring stiffness, ball screw lead, and load resistance. The process of design optimization is presented as an integrated part of the design guidelines, to maximize the system output power and efficiency within practical constraints. In addition, the experimental results of testing a ball screw based energy harvester are presented. The main purpose of conducting the experiment is to observe the performance of the system and validate the dynamic equations of the system. The experimental results that investigate the frequency response, relation between base and relative displacements and the output power profile are in reasonable agreement with the theoretical calculations.

Description: Maximum power point tracking (MPPT) is a key technology in high efficient Photovoltaic (PV) systems. Against the contradiction between the tracking speed and tracking accuracy of the MPPT in the PV systems, this paper presents a self-adaptive step-size MPPT method. First, PV modeling is built under different sunlight intensity and temperatures. Then, by discussing the due features of a self-adaptive step-size function, a new variable step-size function is built based on the logarithm form. Through modeling in Matlab/Simulink and experiment, both results show that the proposed method can improve the MPPT response in both tracking speed and accuracy steadily compared with other published results.

Description: This paper presents results from experimental and numerical investigations on the wave potential extraction of an energy conversion device subjected to regular waves in intermediate water depth. The device is based on a pontoon-type floating breakwater with asymmetric mooring plates. The numerical model is built based on the Navier-Stokes solver coupled with immersed boundary method, volume of fluid method and the mechanics model of energy device. The data obtained in the laboratory investigation suggest that reactive control methods must be employed to optimize the load of the power take off system and maintain the wave energy converter near resonance, which plays an important role in capturing higher wave power. The energy conversion efficiency can reach 14% during experimental runs with only one dynamo installed. Furthermore, by comparing with the experimental results, the applicability of the developed numerical model is demonstrated in predicting the interactions between water waves and the wave power device. With the help of snapshots of water particle velocity field and the wave pressure field from numerical calculation, the flow pattern and external forces from the fluid field can also be estimated. Finally, the effects of mooring angle and the length of floating body on the performance of the energy device are highlighted.

Description: This study estimates the total solar radiation potential over Nairobi City. Several theoretical models based on the initial work of Angstrom have been used to estimate the global solar radiations on a horizontal surface for the city, using bright sunshine hours for the period 2004–2014. The models were developed using the 2004–2012 sunshine hours data and validated by comparing with measured values for 2013 and 2014. Dependencies of the models were tested using Mean Bias Error, Root Mean Square Error, the Nash–Sutcliffe Equation and t -statistics. The result of clearness index for Nairobi shows that the sky is clear all year round except during the June-July-August season where K T is less than 0.5. Most models tested in the current studies were able to adequately estimate daily mean monthly global radiation from sunshine duration with Akinoglu and Ecevit model giving the best estimation.

Description: This paper analyzes the maximum power that a kite, or system of kites, can extract from the wind. First, a number of existing results on kite system efficiency are reviewed. The results that are generally applicable require significant simplifying assumptions, usually neglecting the effects of inertia and gravity. On the other hand, the more precise analyses are usually only applicable to a particular type of kite-power system. Second, a novel result is derived that relates the maximum power output of a kite system to the angle of the average aerodynamic force produced by the system. This result essentially requires no limiting assumptions, and as such it is generally applicable. As it considers average forces that must be balanced, inertial forces are implicitly accounted for. In order to derive practically useful results, the maximum power output is expressed in terms of the system overall strength-to-weight ratio, the tether angle, and the tether drag through an efficiency factor. The result is a simple analytic expression that can be used to calculate the maximum power-producing potential for a system of wings, flying either dynamically or statically, supported by a tether. As an example, the analysis is applied to two systems currently under development, namely, pumping-cycle generators and jet-stream wind power.

Description: Lignocellulosic wastes, inexpensive and potential sources of bioenergy were explored for delignification and production of biogas. Wheat straw was subjected to chemical and biological treatment methods for removal of lignin, facilitating bio-methanation. Pretreatment produced remarkable results with an enhanced amount of methane. Bio-methanation of wheat straw after pretreatment produced biogas with an appreciable methane content (acid treatment 80%, alkaline treatment 74%, thermal treatment 77%, and fungal treatment 92%). Among all, fungal treatment responded to maximum delignification and biogas generation. The method has the potential to be converted to technology for large scale operations.

Description: A new criterion of mixing quality in anaerobic digester based on the most important process parameters of methane fermentation is proposed. A set of numerical studies of mixing quality in anaerobic digesters of cylindrical shape with various systems of hydraulic mixing was carried out. Comparative analysis using the proposed criterion as well as other known methods of evaluation of mixing quality showed that results of evaluation of mixing quality in anaerobic digester using different methods are consistent with each other and are not contradictory.

Description: A vibration harvester is usually designed to work in resonance responding to source vibration. However, in many cases, this source vibration may occur at a wide range of frequencies. If the harvester has very narrow tuning range, it becomes ineffective when there is a mismatch in the frequencies between source excitation and device resonance. Increasing the bandwidth of vibration harvesters has been an important design objective. We propose a two-stage design to improve of a harvester's performance. In a previous work [J. S. Fernando and Q. Sun, Rev. Sci. Instrum. 84 (11), 114704 (2013)], we have demonstrated that use of a two-stage design can increase the power production at a single frequency excitation. In this paper, we will show that a two-stage design can also increase the width of the usable frequency band of the harvester. An optimization routine was used to determine the optimal choice of harvester design parameters with respect to the maximization of an objective function. Experiments were used to verify the electromechanical model as well as the trends predicted by the optimization. Performance comparisons between single- and two-stage harvesters are made through numerical simulation and experiments.

Description: The use of current injection and light exposure is shown to distinguish the impact of degradation in the contact, and intrinsic regions of a-Si:H solar cells, respectively. The drop in the maximum power conversion capability of the cell after light exposure is a consequence of an increase of dangling bonds in the intrinsic layer of the cell due to the Staebler-Wronksi effect. This has a detrimental effect on short circuit current, open circuit voltage, and fill factor. On the other hand, injected current increases the open circuit voltage and greatly reduces the fill factor without affecting the short circuit current, which is attributed to an increase of defects in the p-layer. A clear distinction from both degradation mechanisms is observed from evolution of the ideality factor m of the main junction, and the ideality factor n of the ZnO/a-Si:H(p) interface. A back-to-back diode model of a solar cell that considers the effect of non-ideal contacts, where a high value of n represents an increased tunneling transport at the contact interface, can effectively address the separation of damage in the two regions.

Description: Under shading condition, the power–voltage characteristics of the photovoltaic ( PV ) modules exhibit complexity with multiple numbers of peaks. Existence of multiple peaks leads to additional difficulties in tracking maximum power point ( MPP ) and shall mar efficiency of PV arrays under shading, if appropriate measures are not taken. It is due to the nonlinear characteristics of PV cell, maximum power can be extracted under particular weather condition. Maximum power point tracking (MPPT) techniques are used to maximize PV array output power continuously, by tracking MPP , the location of which depends on atmospheric temperature and solar insolation. The major drawbacks of traditional MPPT techniques are that they are unable to track global peak under non-uniform irradiance/insolation. Numerous techniques are reported in literature to find MPP in both under uniform insolation and partial shading condition. This paper presents a comprehensive review of various MPPT techniques under uniform and non-uniform irradiances and comparatively evaluates them for their merits and demerits. The review is helpful in selecting appropriate MPPT techniques and adjudges its impact on the given solar PV applications.

Description: This paper presents design studies of the gravity-based foundation for a linear generator wave energy converter. The wave energy converter is based on a direct driven generator mounted on the gravity-based foundation located at the seabed. The linear generator is connected to a point absorbing buoy on the sea surface via a connection rope. Such a device, developed at Uppsala University, has been in operation on the Swedish west coast since 2006. Study is focused on the analysis of the impact from undesirable motions of the gravity-based foundation, particularly the study of the tip and lifts phenomena with regard to the heave and surge forces. Long-term extreme significant wave heights are extrapolated from the statistical analysis of the measured wave climate data in the test site where the wave energy converter is deployed. The joint distribution of the significant wave height and the zero-crossing period from the measured wave climate is also analyzed to estimate the associated periods with respect to the long-term extreme significant wave height. The 25 years return extreme significant wave height 4.8 m which is associated with its mean zero-crossing period 8.25 s from the joint distribution is chosen to determine the characteristics of the possible maximum wave for the Lysekil test site. The estimated maximum wave 9.2 m is used to estimate the extreme values of the heave and surge forces on the wave energy converter and the gravity-based foundation. The results with respect to the foundation of a new generation wave energy converter about 35 tons with the presented methodology indicate that a heavier foundation which is about 70 tons needs to be designed in terms of considering the stability of the mooring foundation for long term real sea operation. The purpose of this paper is to propose a reliable approach to estimate the appropriate dimensions for gravity-based foundation of the linear generator wave energy converter and provides a theoretical reference to the construction of the gravity-based foundation.

Description: The aerodynamic and structural coupling optimization of a 1.5 MW wind turbine blade is conducted based on the multi-objective genetic algorithm NSGA-II. Through the optimization of the chord lengths, the twist angles, and the number of laminating, an optimal solution set is obtained, in which the blade is lighter and the generating capacity is higher. Particularly, the fuzzy evaluation is performed after the multi-objective optimization to select the best design adapting to the specific working environment. A new method to determine the membership is proposed instead of experts vote when the fuzzy evaluation is carried out, which contributes to decreasing subjectivity, and saving much time, human and material resources. Hopefully, the method combining the multi-objective optimization and the fuzzy evaluation can be applied to the other similar projects in engineering.

Description: Electricity is usually generated in bulk from large scale conventional power stations and transmitted unidirectional from high to low voltage level where the users are located. More recently, the integration of solar Photovoltaic (PV) systems has been gaining attention in Malaysia given their potential technical benefits and strong governmental support. However, investigation on the potential impact of residential rooftop PV systems on the distribution network has not been properly addressed in the Malaysian context. Therefore, this paper aims to probabilistically assess the impact of different levels of PV penetration on the Malaysian low-voltage (LV) distribution network using the Monte Carlo approach. More specifically, a real and typical residential network in Malaysia has been utilized and used as the test network in this paper. In addition, uncertainties in terms of PV generation intermittency, distribution of the connected PV system capacities as well as allocations of PV systems across the different phases of the network were considered in the study. These allow a more meaningful conclusion to be made. Furthermore, two types of networks, namely, newly developed and matured networks were considered in performing the network impact assessment study. The network output performance metrics include voltage profiles, voltage unbalance, feeder and transformer thermal limits, as well as network losses. The results from the study suggest voltage unbalance and voltage rise are the two main reasons that could limit the higher PV penetration level in typical Malaysian residential LV networks.

Description: Transient process of a pump-turbine, in which the inlet discharge decreases rapidly in pump mode, usually appears due to its frequent switch between pump mode and turbine mode. In order to ensure safe and stable operation, the mechanism of flow characteristics during the transient process was investigated combining numerical and experimental methods. First, steady and unsteady simulations were carried out using the shear-stress transport (SST) k-ω turbulence model under 19 mm guide vane opening. External and internal characteristics under different discharges were presented using numerical simulations based on experimental validation. The results show that the position and area of flow separation as well as appearance of vortices vary with time in the transient process. Finally, the variation of the transient frequency characteristics was obtained through short time Fourier transform. It indicates that main frequencies are blade passing frequency and its harmonic frequencies at the beginning of the transient process, then other complicated frequency components occur as the discharge is reduced, which may come from the vortex motion within the runner.

Description: Earth-to-air heat exchangers (EAHEs) increase the energy performance of passive houses (PHs). The EAHE's performance depends on the climatology of the place and on design and operational parameters. The current commercial practice for implementing EAHEs in the PHs of South-Eastern Europe is by ad litteram importing the existing German design solutions. This is not always a good strategy from the point of view of thermal performance. In this paper, a reference EAHE with fixed design and operational parameters is defined and its performance is studied, when moved in different geographical places in Germany and other Western and South-Eastern European countries. The maximum yearly heating energy for Western Europe is 2730.6 kW h at Stockholm, while in Munich it is 2202.3 kW h. The same quantity in South-Eastern Europe is 2544.4 kW h at Bucharest. The maximum yearly cooling energy in South-Eastern Europe is 973.5 kW h at Belgrade and 739.7 kW h at Bucharest. This quantity is significantly larger than that for Western Europe (149 kW h at Munich). The EAHEs are indeed effective in the climate of South-Eastern Europe, especially as a cooling source during the warm season. Appropriate design solutions and operational parameters are needed in order to obtain the best EAHE's performance. A few practical recommendations for the implementation of EAHEs operating with forced air circulation are given.

Description: Partial shading on photovoltaic (PV) modules reduces the generated power of the PV system than the maximum power generated from each module separately. The shaded PV module acts as a load to unshaded ones which can lead to hot-spot. To alleviate the effect of partial shading, bypass diodes should be connected across each PV modules. Connecting several PV modules together produces multiple peaks (one global peak (GP) and multiple local peaks (LPs)) on partial shading conditions. Maximum power point tracker conventional techniques are designed to follow the GP but they stuck around LPs such as fuzzy logic controller (FLC). In this paper, modified particle swarm optimization (MPSO) using genetic algorism has been used to follow the GP under any operating conditions. MPSO has been studied and compared with the FLC technique to show the superiority of this technique under all operating conditions. Co-simulation between Matlab/Simulink and PSIM has been used to model the PV system under partial shading conditions. The simulation results show that the MPSO technique is more effective than FLC in following the GP. The generated power increases considerably with the MPSO than the FLC technique in shading conditions.

Description: In this study, hybrid bulk heterojunction solar cells with an inverted architecture were fabricated using solution processing techniques. ZnO and TiO 2 nanoparticles were then incorporated to the active layer which primarily consists of poly (3-hexylthiophene) (P3HT) and [6,6] phenyl-C61-butyric acid methyl ester (PCBM). The devices were prepared with varying ratios of PCBM to nanostructured inorganic oxides (ZnO and TiO 2 ) while keeping a fixed amount of P3HT. Various characterization techniques were used to understand the effect of metal oxide nanoparticles on structure, morphology, and performance of resulting devices. It was observed that incorporating an optimum amount of nanoparticles to the active layer increased charge carrier mobility, surface roughness of the active layer, and absorption in visible region leading to a significant increase in power conversion efficiency. However, a significant agglomeration of nanoparticles was observed as their ratio relative to PCBM increased and they completely agglomerated in the absence of the fullerene derivative.

Description: How does one connect two of the most important rivers in the world? In the East, China's longest river, the Yangtze, stretches 6300 km from the Tibetan Plateau to the port of Shanghai. In the West, the longest river in the United States, the Mississippi, runs 5970 km from northern Minnesota down to the Gulf of Mexico. Both rivers play vital roles in the cultures and economies of their respective countries. Each river system gives life to a wealth of biodiversity while providing millions of people with drinking water, hydroelectric power, and a number of other services. The vitality of the Yangtze and Mississippi faces challenges, however, and the fisheries resources of these two great rivers face specific and common threats. That is why The Nature Conservancy and the Yangtze River Basin Fisheries Resources Management Commission (YFC) came together to form an EcoPartnership to help preserve the natural fisheries of these two great rivers. (Note: YFC recently became the Yangtze Fisheries Bureau, with fisheries responsibilities for all rivers in China from the Yangtze on south and greater administrative authority. The great rivers partnership logo uses the rubric of the Changjiang Fisheries Agency, retaining the Chinese pinyin for the name of the river.

Description: As flood is discharged in the high dam, vibrations are generated and transmitted to the surrounding ground, causing vibrations in adjacent structures. The vibration can sometimes reach such a high level that can be harmful to the neighboring residents and buildings, which is an undesirable phenomenon and should be prevented. In this study, an attempt has been made to identify the vibration sources, analyze the law of vibration propagation, and establish the relationship between the vibration sources and ground vibration using the Time-Wavelet Power Spectrum and the Cross Wavelet Transform techniques. The results reveal that the flow fluctuating loads generated by different discharge structures are the main cause of the ground vibration. The contribution from each vibration source as well as its attenuation during propagation is different, based on the ways of flood discharge and composition of the grounds. The results lay a good foundation for controlling the ground vibration induced by flood discharge of high dams in the future.

Description: There are numerous sources of mechanical energy in our environment, such as ultrasonic waves, body movement, and irregular air flow/vibration. Here, we present a simple, cost-effective approach for fabricating a flexible nanogenerator and apply it to harvest energy from environmental mechanical vibrations. The nanogenerator was based on ZnO nanorods grown on common paper substrate using a low-temperature hydrothermal method. Piezoelectric currents were measured by attaching the nanogenerator on the surface of a cantilever and a wind-up drum, respectively. At the same time, the vibrations of the cantilever and wind-up drum could also be characterized by the corresponding output signals. This is a practical and versatile technology with the potential for converting a variety of environment energy into electric energy, and also with the application for pre-warning of emergency, such as earthquake and burgling.

Description: Estimates of the amount of land used for a defined amount of utility-scale electricity generation in the solar power industry, referred to as solar land use energy intensity (LUEI), are important to decision makers for evaluating the environmental impact of energy technology choices. In general, solar energy tends to have a larger on-site LUEI than that of fossil fuels because the energy generated per square meter of power plant area is much lower. Unfortunately, there are few studies that quantify the off-site LUEI for utility-scale solar energy, and of those that do, they share common methodologies and data sets. In this study, we develop a new method for calculating the off-site LUEI for utility-scale solar energy for three different technologies: silicon photovoltaic (Si-PV), cadmium-telluride (CdTe) PV, and parabolic trough concentrated solar thermal. Our results indicate that the off-site LUEI is most likely 1% or less of the on-site LUEI for each technology. Although our results have some inherent uncertainties, they fall within an order of magnitude of other estimates in the literature.

Description: This paper presents the performance of a wind power system under failures in the lubricant system, and a procedure is proposed to detect the failure. According to the fact that the friction torque caused by the lubricant system, failure makes the maximum power point (MPP) of the wind system to be smaller than that of normal operation; for MPP tracking operations, the difference between actual and simulated (estimated) output power of the wind system is an indicator for the lubricant system failure. However, for non-MPP tracking operations, in which the demanded power is small enough to be satisfied by the failed wind system, the above indicator cannot be used to detect the lubricant system failure. In this case, the predetermined angular shaft speed ratio is used to detect the lubricant system failure. Moreover, the converter failure is considered in this paper, and a model-based fault detection filter is designed to detect the DC/DC converter failure in a wind system. The proposed detection filter consists of an observer combined with a residual signal generator, where the driving torque is assumed as an unknown bounded input in the proposed failure detection scheme. Numerical simulation results support the proposed detection procedures.

Description: Research on hybrid systems has emerged in recent years due to the current and growing global interest in the search for energy resources that lead to a decrease in fossil fuel use for power generation. Such systems are coupled to both conventional and non-conventional sources. Therefore, in this paper we present a review of hybrid energy systems, with emphasis on those which are engaged in photovoltaic solar energy. The purpose is to identify the different integration frameworks and types of storage capacities according to energy demand, geographic area, and other parameters. Finally, an overview of Mexico in relation to hybrid systems is presented as an attempt to motivate researchers, industry, and government to implement and develop these systems.

Description: This paper proposes a fuzzy control method for tracking maximum power point in photovoltaic (PV) power systems to solve a fast irradiation change problem. Perturb and Observe (P&O) is known as a very simple maximum power point tracking and is extensively disseminated. Fuzzy logic is also simple to investigate and provides fast dynamics. The suggested technique combines both fuzzy logic and P&O advantages. A fuzzy logic-based P&O algorithm is illustrated to identify the fault direction tracking of conventional P&O algorithm under trapezoidal irradiation change. The proposed algorithm is verified using Matlab/Simulink™ software. The robust tracking capability under rapidly increasing and decreasing irradiance is verified experimentally with a PV array emulator. Simulation and experimental results confirm that the proposed algorithm provides effective, fast, and accurate tracking compared to the conventional P&O algorithm.

Description: The increasing penetration of distributed generators (DGs) makes further interconnection of multiple energy carriers possible. In this paper, an integration model comprising IEEE-33 bus distribution network and a correspondingly designed water system is proposed with DG coupling of thermal and electrical energy. The integrated energy system incorporates the constraints of the distribution network, water system, and DGs and ensures that the electrical and thermal demands of the integrated energy system are satisfied simultaneously by energy flow. An optimal procedure including optimal sizing, positioning, and operation of DGs and gas boilers in a given system was implemented while minimizing the total costs of investment and operation. The model constitutes a mixed integer nonlinear problem, as it takes the power flow calculation and the nonlinear characteristics of DG efficiency into consideration. Therefore, the particle swarm optimization algorithm is employed to simulate the proposed model. The simulation results in conjunction with numerical studies reveal the impact of the water system on the optimal configuration of DGs and the advantages of the integrated energy system on economic considerations, voltage level, and net loss.

Description: Developing countries like Pakistan need a continuous supply of clean and cheap energy. It is a very common fear in today's world that the fossil fuels will be depleted soon and the cost of energy is increasing day-by-day. Renewable energy sources and technologies have the potential to provide solutions to long-standing energy problems faced by developing countries. Currently, Pakistan is experiencing a critical energy crisis and renewable energy resources can be the best alternatives for quickly terminating the need for fossil fuels. The renewable energy sources such as solar energy, wind energy, and biomass energy combined with fuel cell technology can be used to overcome the energy shortage in Pakistan. Biomass is a promising renewable energy source and is gaining more interest because it produces a similar type of fuel like crude oil and natural gas. Energy from biomass only depends upon the availability of raw materials; therefore, biomass can play an important role to fulfill the energy requirements of the modern age. The use of energy has increased greatly since the last century and almost all human activities have become more dependent on energy. Biomass, being a potential and indigenous candidate, could be a good solution to meet the energy needs of Pakistan. In this review paper, the detailed current energy requirements and solutions from available energy resources and the scope, potential, and implementation of biomass conversion to energy in Pakistan are explored with a special focus on the major province of Punjab and the advantages of biomass for energy purposes.

Description: Reducing wake losses in wind farms by deflecting the wakes through turbine yawing has been shown to be a feasible wind farm controls approach. Nonetheless, the effectiveness of yawing depends not only on the degree of wake deflection but also on the resulting shape of the wake. In this work, the deflection and morphology of wakes behind a porous disk model of a wind turbine operating in yawed conditions are studied using wind tunnel experiments and uniform inflow. First, by measuring velocity distributions at various downstream positions and comparing with prior studies, we confirm that the non-rotating porous disk wind turbine model in yaw generates realistic wake deflections. Second, we characterize the wake shape and make observations of what is termed as curled wake, displaying significant spanwise asymmetry. The wake curling observed in the experiments is also reproduced qualitatively in Large Eddy Simulations using both actuator disk and actuator line models. Results suggest that when a wind turbine is yawed for the benefit of downstream turbines, the curled shape of the wake and its asymmetry must be taken into account since it affects how much of it intersects the downstream turbines.

Description: Changes in the topology of distribution networks which is due to connecting or disconnecting of distributed generations (DGs) is a critical challenge in maintaining protection coordination in these networks. Protection coordination is generally retrieved after deciding optimal capacity and location of installing DGs. Nevertheless, in this paper, a new method is presented which merges the protection coordination of distribution networks in the process of sizing and siting DGs. The presented approach of this paper, in addition to identifying the optimal location and capacity of DGs with the purpose of increasing the benefits and reducing cost of installing these resources, is to also create a robust protection coordination. In order to provide a robust protection coordination, the capacity and location of fault current limiters are identified parallel with sizing and siting DGs. The protection coordination considered in this paper results in grouping different topologies of the network according to allowable memory of protective relays. On this basis, the protection coordination of all operational topologies of the network is guaranteed. In order to coordinate each group interval linear programming is suggested. This method reduces the number of protection coordination constraints of each group and simplifies appropriate protection coordination for the group. The proposed method is tested on Zanjan Regional Electric Board, Iran. Simulation results are reported and discussed.

Description: Vegetable insulating oils (VIOs) have attracted wide attention for their high flash point, high insulation performance and degradability. However, the unsaturated fatty acids contained in VIOs reduce their oxidation stability, which requires the addition of some antioxidants to ensure their usage. Here, we establish a high-performance liquid chromatography (HPLC) method for determination of antioxidants in VIOs. The standard calibration curves of 3 analytes (PG, BHA, BHT) all show high linearity, and the correlation coefficients are all above 0.9994. Limits of detection of all three analytes range from 0.003 to 0.010 mg/ml; limits of quantitation range from 0.010 to 0.033 mg/ml. The new HPLC method is proved ideally suitable for the analysis of commercialized transformer oil Cooper-FR3 with precision (%RSD = 0.3%–0.7%) and accuracy (%recovery = 100.0%–102.1%), suggesting that this method is an efficient tool for routine screening of antioxidant contents in VIOs. We used this method to monitor the changes of antioxidant contents in the oxidation of two VIOs–soybean oil and rapeseed oil.

Description: This paper introduces a stochastic reliability evaluation methodology for quantifying the impact of unmanaged plug-in hybrid electric vehicles (PHEVs') charging on the transformers' hottest spot temperature (HST)-dependent aging failures. Further, a novel PHEVs' charging management method has been proposed from the distribution transformers' dynamic thermal modeling perspective. The proposed reliability evaluation method provided the precise stochastic model corresponding to the PHEV owners' behavior. The introduced reliability evaluation methodology has been applied to an actual distribution system of the Hormozgan Regional Electrical Company in Iran under various PHEVs' charging scenarios. The numerical results imply that the distribution transformers' failures are adversely affected due to unmanaged PHEVs charging. The system under study has been simulated during a 10-year-period. The test results show that the transformers' HST-dependent failures due to the PHEVs' charging demand load exponentially increased as a function of system age. As revealed by the results, the proposed PHEVs' charging management methodology mitigates the aggregated peak load and transformers' HST by deferring the peak charging load to midnight.

Description: Under partial shading conditions, the power–voltage (P-U) curve may exhibit multiple local maxima. This makes it challenging to track the global maximum power point (GMPP). Additionally, in such conditions, conventional maximum power point tracking (MPPT) methods cannot be used to extract the GMPP. This paper describes a modified firefly algorithm (MFA) that can rapidly and accurately extract the GMPP under partial shading conditions. The algorithm introduces the concepts of the global and local firefly densities during each iteration, and devises two elimination mechanisms to adaptively adjust the firefly population. The proposed method is compared with the traditional MPPT algorithms under four different partial shading conditions. Simulation results demonstrate that the MFA can immediately and accurately track the global maximum under the partially shaded conditions, and that the proposed method outperforms conventional techniques in terms of tracking efficiency and speed.

Description: The parameters influencing gas alternative water (WAG) for CO 2 flooding in the low permeability block of the Jilin oil fields in China were investigated using the numerical simulation software, Eclipse. The minimum miscibility pressure was first determined based on slim tube tests. Comparisons were made between continuous water flooding, continuous CO 2 flooding, and WAG flooding methods. The oil recovery ratio of “gas injection first method” was higher than that of “water injection first method” and the mechanism of CO 2 displacement was analyzed. The optimum parameters for WAG flooding were 7 for the number of slugs, 0.3845 PV for the total injection volume, approximately 0.5742 for the gas/water slug ratio, and 120 days for the stewing time. The optimum injection timing of the switching depletion development to the WAG injection was 0.25 years and the earlier switching to the WAG injection after water flooding was more suitable for enhanced oil recovery. The maximal cumulative water injection by water flooding or by WAG flooding yielded the highest oil recovery ratio for homogeneous reservoir. The results do not only play a very important role in optimizing different development schemes but also provide theoretical basis for CO 2 flooding in low permeability hydrocarbon reservoirs.

Description: Experimental results on the performances of ten solar stills with different glass inclination angles are presented. The inclination angles selected are 10–55 in steps of 5°. Results demonstrate that the angles between 30° and 35° may be associated with the least still performance while those between 20° and 25° provide the optimum performance as far as the clean water productivity and cost effectiveness are concerned. Empirical modeling of the still operation produced good agreement with the experimental data.

Description: Water intake structure is an important element technology for small hydroelectric generation. Currently, intake structures with bar screens have been broadly introduced; however, these require constant maintenance to avoid the clogging of bars by dust or gravel. This study considers the optimal structure of bottom intakes by focusing on two criteria: efficient water intake and prevention of clogs by trapping trash. Grating was selected as the intake structure because it is convenient to construct, widely available, and cheaper than other materials. A flume experiment was conducted to examine the relation between the grating structure and the intake efficiency and trash-trapping rate. Results indicate a clear linear relation between the installation angle and water intake capacity. Furthermore, the trash-trapping rate is low for gratings that have high opening area ratios because their surface areas are small and friction resistance is low.

Description: Earth-abundant kesterite Cu 2 ZnSnSe 4 material is a promising candidate for the mass production of low-cost thin film solar cells. However, the synthesis of single-phase kesterite films is especially challenging, since the kesterite single-phase region in the equilibrium phase diagram is very narrow. In this study, the metal composition was varied within the Cu-poor composition range in order to study the presence of Sn-Se secondary phases. Both SnSe and SnSe 2 are found in copper-poor CZTSe absorbers where Zn/Sn   1 because the studied composition range is actually copper-poor zinc-rich and tin-rich. The Sn-Se secondary phases can be detected using X-ray diffraction, a bulk detection method. They are also detected at the absorber's surface by SEM and Raman spectroscopy. Therefore, when the Sn-Se phases are present, at least a part of them is located at the absorber's surface, which is highly detrimental to device performance. Acting as shunting paths, they reduce the device power conversion efficiency and demonstrate an apparent quantum efficiency effect under reverse bias. Removal of these phases from the surface by chemical etching greatly reduces their detrimental influence.

Description: Solar irradiation is the main potential energy source used in various processes. An accurate estimation of solar irradiation becomes a challenge due to the unavailability of weather data in Algeria. Therefore, an operated model can offer an important alternative for calculating the solar irradiation including the minimum of the input data. The present study derives a simple model from a review of our previously published work. It aims to develop a new approach for the estimation of the global irradiation on the horizontal plane only based on the measured sunshine duration. Maps of solar energy are required by many system designs; for this reason, it is mandatory to draw the global solar irradiation maps for Algeria for all types of sky. Algebraic relative errors were used as indicators of the agreement between the experimental and the calculated global irradiation. It has been proved that the highest intensity of the solar irradiation is located around the area of Djanet and Tamanrasset, whereas the less intense area extends from Skikda zone to Annaba, and more exactly in around 7° longitude.

Description: A Luminescent Solar Concentrator (LSC) greenhouse and an identical control greenhouse were constructed with photovoltaic (PV) cells attached to the roof panels of both structures. The placement and types of PV cells used in the LSC panels were varied for performance comparisons. Solar power generation was monitored continuously for one year, with leading LSC panels exhibiting a 37% increase in power production compared to the reference. The 22.3 m 2 greenhouse was projected to generate a total of 1342 kWh per year, or 57.4 kWh/m 2 if it were composed solely of the leading panel of Criss Cross panel design. The LSC panels showed no signs of degradation throughout the trial demonstrating the material's robustness in field conditions.

Description: This paper presents the performance analysis of a new maximum power point tracking (MPPT) algorithm for solar photovoltaic (SPV) system using LUO converter. For effective utilization of the SPV panel, MPPT is essential. Hence, it is significant to simplify the tracking control algorithm with faster response, reduced ripple, higher efficiency, and cost-effective system. The proposed technique performs MPPT using a simple control technique by fine-tuning the duty cycle of the converter so as to make the input resistance of converter equal to the load resistance of the solar panel. Hence, the need for proportional–integral control loop is eliminated. The performance analysis of the proposed MPPT algorithm is compared with an existing perturb-and-observe algorithm in MATLAB simulation and experiment results of the proposed MPPT is implemented with the field programmable gate array controller using LUO converter with 40 W solar panel. From the results, it is proved that the response of the proposed method is faster than the existing perturb-and-observe method under varying solar irradiation conditions for the same step size. The input and output side ripples are considerably low and also the proposed algorithm has higher efficiency and low cost.

Description: The environmental concerns are gaining importance nowadays for power producing companies in the context of clean energy act. The efforts of reducing the harmful emissions beyond a certain level are being made by most of the power utilities in the developing countries. Consequently, the minimization of harmful emissions has also become an important objective function while solving the hydrothermal scheduling problem. The heuristic approaches are considered as potential solution methodologies for non-convex hydrothermal scheduling. This paper presents an Evaporation Rate based Water Cycle Algorithm (ERWCA) for the solution of non-convex Environmental Economic Scheduling of Hydrothermal Energy Systems (EESHES). This algorithm has been evolved from the water cycle nature of raining, formation of streams, and their movement towards the rivers and finally into the sea. ERWCA has been investigated on the standard test system of EESHES with three case studies: (i) Economic Cost Scheduling, (ii) Environmental Economic Scheduling, (iii) Economic Environmental and Cost Scheduling. The comparison of obtained results with the recent results in the literature shows the superiority of ERWCA in terms of both lower fuel cost and fuel emissions. Hence, ERWCA is a worthwhile addition to the algorithms which have successfully solved this complex and combinatorial bi-objective optimization problem.

Description: With the deterioration of the global greenhouse effect, the study of carbon dioxide emissions has received more and more international attention and accurate prediction of carbon dioxide emissions is also important for the formulation of reasonable energy-saving emission reduction measures. In this paper, the genetic algorithm is used to optimize the initial connection weights and thresholds of the traditional back propagation neural network (BPNN) which can give full play to the advantages of the genetic algorithm's global search capacity and BPNN's local search. The data of Hebei province in China during the period 1978–2012 are selected to carry out the carbon dioxide emissions prediction with the established model. In the view of the choice of input variables, the coal consumption, gross domestic product, total population, and urbanization level are examined by Pearson coefficient test. Auto correlation and partial correlation are applied to analyze the inner relationships between the historic carbon dioxide emissions, thus to select the input variables of BPNN. Besides, in order to verify the validity of the built model, the residual auto correlation and partial correlation are done upon the training set. The prediction results suggest the proposed model outperforms the compared models.

Description: A recent trend of the power system is the ever increasing number of distributed generators (DGs) utilizing renewable energy sources, which have output powers that fluctuate due to unpredictable weather and ambient conditions. This causes fluctuations in system frequency and bus voltages, resulting in poor quality power, higher prices for electricity, and increased chances of reverse power flow and voltage collapse. In order to allow higher levels of DG penetration, methods of reducing the effects of fluctuations must be implemented. This paper proposes a method to mitigate these fluctuations using controllable loads such as heat pump water heaters (HPs) and battery storage systems. The HPs are controlled using a decentralized bang-bang (on/off) control based on the cumulative distribution of water temperature of HPs in the local area and the local frequency. Battery systems are controlled using a smart frequency and voltage droop characteristics based control. The decentralized bang-bang control mitigates local frequency fluctuations by increasing active power consumption to lower frequency as well as decreasing active power consumption to increase the frequency. The smart droop characteristics based control applies a commonly used droop characteristics control to voltage and frequency; however, the control system monitors the state of charge (SOC) of the battery system and takes appropriate actions to prevent the SOC from reaching a critical level. The results of simulations show that fluctuations in frequency and bus voltage are mitigated by the application of the proposed control methodologies without adversely affecting the comfort level of consumers.

Description: This paper presents a model-based algorithm for fast tracking of maximum power point of a photovoltaic panel. Parameters of an equivalent circuit have been estimated based on experimental data and characteristic data provided by manufacturer. Since photoelectric current is highly temperature-dependent, the effect of temperature is considered in the model. The proposed method is based on the maximum power point locus of the solar panel. So the tracking speed is much faster than a model-free method. In the suggested technique, the voltage of maximum power point can be determined using output voltage and current of solar panel and the voltage of a point on the maximum power point locus with the same current, in three steps. The main novelty of the proposed model-based method is that there is no need to measure solar radiation. Experiment results are presented and prove the feasibility of the proposed maximum power point tracking method.

Description: Kui Wang, Jianchun Jiang, Zhan Si, and Xinyu Liang A solid acid catalyst SO/TiO/La was prepared via sol-gel method using tetrabutyl titanate as TiO precursor. The catalyst simultaneously catalyzed esterification and transesterification resulting in the synthesis of biodiesel from waste cooking oil with high content of free fatty acids as feedstock. ... [J. Renewable Sustainable Energy 5, 052001 (2013)] published Mon Sep 9, 2013.

Description: Giorgos Markou and Dimitris Georgakakis In this study, maize silage was anaerobically mono- and co-digested together with low solid swine wastewater in a novel two-state (liquid/solid) anaerobic digester. The special subject of the two-state digester is that operates with both, liquid and solid fractions, which are present in a segregated ... [J. Renewable Sustainable Energy 5, 053107 (2013)] published Fri Sep 13, 2013.

Description: Jung Yup Yang, Young Kyoung Ahn, Pil Ho Huh, Jung Gyu Nam, Min Park et al. After producing crystalline Si (c-Si) solar module, the output power of the c-Si module was decreased compared to the total amount of c-Si cells' power due to the increase of series resistance and the light absorption of the cover glass and encapsulant. We define this power loss as cell to module (C ... [J. Renewable Sustainable Energy 5, 052003 (2013)] published Fri Sep 13, 2013.

Description: Wenjing Qin, Xinrui Xu, Dongyue Liu, Chunyu Ma, Liying Yang et al. ZnO is a promising material used as the electron transport layer in the inverted organic solar cells (IOSCs). However, the electrical or photoelectric properties of ZnO nanoparticles are governed by the surface states of the nanoparticles. Here, we demonstrate that the large number of hydroxyl (-OH) ... [J. Renewable Sustainable Energy 5, 053106 (2013)] published Fri Sep 13, 2013.

Description: A. Khiareddine, C. Ben Salah, and M. F. Mimouni The use of renewable energy is growing significantly in the world. In front of the growing demand for electric energy, essentially for the needs of remote, desolate, and mountainous regions, photovoltaic systems, especially water pumping systems, are beginning to emerge in large applications. In thi ... [J. Renewable Sustainable Energy 5, 053109 (2013)] published Tue Sep 17, 2013.

Description: Robert Kennedy Smith and Benjamin F. Hobbs Electricity generation from the combustion of biomass feedstocks provides low-carbon energy that is not as geographically constricted as other renewable technologies. This study uses non-linear programming to provide policymakers with scenarios of possible sources of biomass for power generation as ... [J. Renewable Sustainable Energy 5, 053118 (2013)] published Thu Sep 19, 2013.

Description: Hongyan Wang, Yimin Cao, Dan Li, Usman Muhammad, Chunshan Li et al. In the perspective of fossil fuel depletion, the importance of renewable and substitute fuels is remarkable. In this study, clean liquid-fuel was obtained from tar through catalytic hydrorefining method. Hydrorefining catalysts were prepared by impregnation, containing tungsten-nickel (W-Ni), molybd ... [J. Renewable Sustainable Energy 5, 053114 (2013)] published Thu Sep 19, 2013.

Description: Puyang Zhang, Hongyan Ding, Conghuan Le, and Xu Huang With the current state of offshore wind turbine construction technology, a major marine spread is necessary for the installation of the foundation, tower, and turbine. It is advantageous for offshore installation to be integrated into a single operation. The large-scale composite bucket foundation i ... [J. Renewable Sustainable Energy 5, 053117 (2013)] published Thu Sep 19, 2013.

Description: J. Chen, J. C. Jiang, X. A. Nie, J. M. Xu, X. Chang et al. The process of producing diesel-like fuel from combination of catalytic cracking with catalytic esterification was studied. The optimal technological conditions were obtained as follows: CaO as cracking catalyst, distillation temperature 320 350 degrees C, cracking temperature 480 500 degrees C, ... [J. Renewable Sustainable Energy 5, 052004 (2013)] published Thu Sep 19, 2013.

Description: Yanji Li, Kewei Zou, Tianhua Yang, Rundong Li, and Yong Chi Combustible solid waste gasification was simulated with Aspen Plus based on the principle of Gibbs free energy as well as mass and energy balance. Preheated air temperature and air equivalence ratio (ER) were found to have a crucial influence on gasification characteristics under 600 degrees C gas ... [J. Renewable Sustainable Energy 5, 053113 (2013)] published Thu Sep 19, 2013.

Description: Sajjad Saberi and Mehdi Karrari In recent years with the increasing use of wind generators in power systems, the issue of keeping these generators stable and maintaining their connection to the network in the presence of fault or voltage sag has gained a great importance. In this paper some enhancement methods for the low voltage ... [J. Renewable Sustainable Energy 5, 053116 (2013)] published Thu Sep 19, 2013.

Description: M. Whittle, J. Trevelyan, and P. J. Tavner Increasing the availability of multi-megawatt wind turbines (WT) is necessary if the cost of energy generated by wind is to be reduced. It has been found that WT generator bearings have a surprisingly high failure rate, with failures happening too early to be due to classical rolling contact fatigue ... [J. Renewable Sustainable Energy 5, 053128 (2013)] published Thu Sep 26, 2013.

Description: H. J. Chen, Q. Cui, Q. G. Li, K. Zheng, and H. Q. Yao SAPO (silico-alumino-phosphate) molecular sieves might be promising for adsorption refrigeration driven by low-grade heat source due to their weak polar frameworks. The SAPO-34 molecular sieve was synthesized using a hydrothermal method. Its crystal phase, morphology, and microstructure were charact ... [J. Renewable Sustainable Energy 5, 053129 (2013)] published Tue Oct 1, 2013.

Description: Antonio de la Villa Jaen, Dan El Montoya Andrade, and Agustin Garcia Santana The control strategy applied to the oscillating system of the wave energy converters largely determines the overall system efficiency and thus the energy production. One of the first proposed control strategies for this type of device is the passive control. This type of control continues currently ... [J. Renewable Sustainable Energy 5, 053132 (2013)] published Wed Oct 2, 2013.

Description: Bhagyashre Pani and Udai P. Singh Kesterite-type CZTS (CuZnSnS) is an emerging absorber material to be used in thin film solar cells. Here, we report a simple and convenient route to synthesize CZTS thin film by using ball milled metallic precursors; paste preparation by using propylene glycol as binder despite of using too many che ... [J. Renewable Sustainable Energy 5, 053131 (2013)] published Wed Oct 2, 2013.

Description: J. B. Zhao, G. X. Zhang, X. R. Wang, and D. H. Zou Distribution state estimation (DSE) is becoming more and more important in distribution control center considering deregulation and introduction of renewable sources based distributed generations (REDGs). To realize the real-time estimation of the load and REDGs output values with limited monitoring ... [J. Renewable Sustainable Energy 5, 053133 (2013)] published Wed Oct 2, 2013.

Description: Kojo Atta Aikins and Jong Min Choi There is a need for hot water generation in a more efficient and environmentally friendly way for heating, ventilating, and air conditioning systems, and the heat pump is a great candidate for that. In this paper, hot water temperatures generated by ground source heat pump (GSHP) systems in Korea ar ... [J. Renewable Sustainable Energy 5, 052002 (2013)] published Fri Sep 13, 2013.

Description: Hesan Ziar and Hossein Kazemi Karegar Photovoltaic panels are very sensitive to environmental conditions. Study and formulation of this sensitivity lead to improvement of photovoltaic systems. Parameter which shows the rate of impact of environmental conditions on photovoltaic panels is Fill Factor (FF). In this paper, sensitivity of Fi ... [J. Renewable Sustainable Energy 5, 053108 (2013)] published Fri Sep 13, 2013.

Description: A. T. Soares, B. F. Silva, L. L. Fialho, M. A. G. Pequeno, A. A. H. Vieira et al. The fatty acid methyl ester and triacylglyceride content of the oils of seven microalgae species were analyzed by gas chromatography in order to predict the influence of fatty acid content on the physicochemical properties of biodiesel. Among the seven species examined, Chlorella minutissima and Art ... [J. Renewable Sustainable Energy 5, 053111 (2013)] published Tue Sep 17, 2013.

Description: Hsi-Chien Liu and Gou-Jen Wang In this paper, a novel two-stage metal-assisted etching (MAE) method is proposed for the fabrication of a high anti-reflection silicon nanowire array. In the first stage of etching, a high-concentration etchant is implemented in a short etching time to enable the uniform and complete deposition of c ... [J. Renewable Sustainable Energy 5, 053115 (2013)] published Thu Sep 19, 2013.

Description: N. Balakrishnan and K. Mayilsamy Oxidative thermal degradation and flame retardant behavior of cotton with intumescent formulations containing nanoclay as well as biodiesel (B0, B23, and B100) are studied by thermogravimetry (TG), differential thermal analysis, and limiting oxygen index (LOI). Activation energy of thermal degradati ... [J. Renewable Sustainable Energy 5, 053121 (2013)] published Mon Sep 23, 2013.

Description: D. Jayaweera, S. Islam, and S. Neduvelil Distribution networks are limited with spare capacities to integrate increased volumes of distributed generation (DG). Network constraints and congestion, dynamic thermal limits, intermittent outputs, and the need for reduction in greenhouse gas emission increase the complexity of capturing optimal ... [J. Renewable Sustainable Energy 5, 053120 (2013)] published Mon Sep 23, 2013.

Description: Reda A. I. Abou-Shanab, Seong-Heon Kim, Min-Kyu Ji, Sang-Hun Lee, Hyun-Seog Roh et al. Municipal wastewater is a major problem due to its high concentration of nutrients, which can cause eutrophication of the surrounding water, resulting in serious disturbance in health and ecosystem. Microalgae can utilize nitrogen and phosphorus in wastewater as a potential source of cost effective ... [J. Renewable Sustainable Energy 5, 052006 (2013)] published Mon Sep 23, 2013.

Description: Krishnil R. Ram, Sunil Lal, and M. Rafiuddin Ahmed Optimization of a low Reynolds number airfoil for use in small wind turbines is carried out using a Genetic Algorithm (GA) optimization technique. With the aim of creating a roughness insensitive airfoil for the tip region of turbine blades, a multi-objective genetic algorithm code is developed. A r ... [J. Renewable Sustainable Energy 5, 052007 (2013)] published Mon Sep 23, 2013.

Description: Mostafa Mehrtash, Daniel R. Rousse, and Guillermo Quesada This paper deals with demonstrating the energy performance of solar tracking photovoltaic (PV) systems in Canada. In this study, a grid connected stand-alone PV system has been designed and coupled with four different tracking systems: fixed horizontal, fixed tilted, single-axis tracking, and dual-a ... [J. Renewable Sustainable Energy 5, 053119 (2013)] published Mon Sep 23, 2013.

Description: Yeolwan Seong, Seunghoon Lee, Doo Young Gwak, Yoonho Cho, Jiyoung Hong et al. Wind turbine noise referred to as swishing sound causes annoyance due to the amplitude modulation of the noise aerodynamically generated from blades. For the propagation characteristic of sound emitted from blade, the noise can be heard differently from place to place. For that reason, many studies ... [J. Renewable Sustainable Energy 5, 052008 (2013)] published Fri Sep 27, 2013.

Description: Arghya Bhowmik, Tanmay Sarkar, Arun Kumar Varanasi, Umesh V. Waghmare, and Mridula Dixit Bharadwaj We use first-principles density functional theory based calculations and topological analysis of the electronic charge density in lithiated and delithiated forms of olivine phosphates (LiMPO), an important class of cathode materials for Li-ion batteries, to determine the electronic mechanisms that g ... [J. Renewable Sustainable Energy 5, 053130 (2013)] published Tue Oct 1, 2013.

Description: Bo Sun, Jun Mei, Jianyong Zheng, and Kai Deng Compared with traditional Z-source and quasi-Z-source inverter, switched-inductor quasi-Z-source has higher booster multiple, lower capacitance stress, and higher conversion efficiency. Therefore, it is very suitable for grid-connected photovoltaic power generation system. This paper analyzes the vo ... [J. Renewable Sustainable Energy 5, 033120 (2013)] published Wed Jun 5, 2013.

Description: S. Pradhan and A. Dhar We report here the formation of vertical N,N[prime]-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C) nanostructure with simple chemical treatment over thermally evaporated thin film of PTCDI-C. Here, we have used PTCDI-C nanostructures as an electron accepting material and a conjugated polymer as an ... [J. Renewable Sustainable Energy 5, 031611 (2013)] published Wed Jun 5, 2013.

Description: Chandan Ashis Gupta, S. Mangal, and U. P. Singh Doped and co-doped ZnO thin films are currently under intense investigation and development for optoelectronic and solar cell applications. Here in this study Aluminum and Boron (ZAB), Gallium and Boron (ZGB), and Gallium and Aluminum (ZGA) co-doped ZnO thin films were deposited on glass substrate u ... [J. Renewable Sustainable Energy 5, 031609 (2013)] published Wed Jun 5, 2013.

Description: M. Laihanen, A. Karhunen, and T. Ranta In Finland, it is estimated that forest biomass will be the main source of bioenergy when meeting the national target of 38% renewable from final energy consumption by 2020. Achieving this target means that concrete actions on increasing the use of renewable energy have to take place in regional lev ... [J. Renewable Sustainable Energy 5, 033121 (2013)] published Wed Jun 5, 2013.

Description: Sinan Kivrak The two most important parameters in generating electrical energy from photovoltaic panels are the amount of sun radiance and sunshine duration. Because sunshine duration cannot be consistently relied upon, the most important factor is to utilize sun radiance at an optimum level. In the consequence ... [J. Renewable Sustainable Energy 5, 033119 (2013)] published Wed Jun 5, 2013.

Description: U. Chalapathi, S. Uthanna, and V. Sundara Raja Thin films of CuZnSnS (CZTS), a potential absorber layer for thin film heterojunction solar cells, have been successfully grown on soda-lime glass substrates held at 450 [convolution]C using co-evaporation technique. Cu, Sn, ZnS, and S, kept in molybdenum boats, are used as the source materials. The ... [J. Renewable Sustainable Energy 5, 031610 (2013)] published Wed Jun 5, 2013.

Description: Aparajita Mandal and Partha Chaudhuri In this paper, we have used Finite Difference Time Domain method for numerically calculating the absorption spectra within a thin layer of hydrogenated amorphous silicon (a-Si:H) with the front surface regularly patterned with spherical Ag nano particles. We have considered a wide range of particle ... [J. Renewable Sustainable Energy 5, 031614 (2013)] published Tue Jun 11, 2013.

Description: T. P. Otanicar, R. A. Taylor, and C. Telang Hybrid photovoltaic/thermal (PV/T) collectors would benefit from the use of fluid based optical filters as a means to separate the useful irradiance for the PV cell from those wavelengths which are more suited to heat generation. Nanoparticle based dispersions within a working fluid can be designed/ ... [J. Renewable Sustainable Energy 5, 033124 (2013)] published Tue Jun 11, 2013.

Description: D. Ketata and and L. Krichen This paper focuses on Distributed Generator (DG) integration in Power Electrical System (PES) for dispersed nodes. The main objective of the DG use can be classified into two aspects: a load following service and ancillary service systems. In this study, the DG system contains a Fuel cell and a Supe ... [J. Renewable Sustainable Energy 5, 033122 (2013)] published Tue Jun 11, 2013.

Description: R. Aparna, N. Sivakumar, A. Balakrishnan, A. Sreekumar Nair, Shantikumar V. Nair et al. In this paper, a simple, cost effective, and scalable process for production of few-layer graphene is reported by combining ball milling with exfoliants. The graphene was derived from low-cost graphite, which was subjected to high-energy ball milling in an aqueous medium containing a strong exfolian ... [J. Renewable Sustainable Energy 5, 033123 (2013)] published Tue Jun 11, 2013.

Description: Shivaji M. Sonawane and N. B. Chaure Antimony telluride (SbTe) is binary p-type compound of narrow band gap (0.3 eV) semiconductor, which has application in solar cell to make low resistive ohmic contact. SbTe acts as a diffusion barrier and may improve the ohmic contact due to top doping on CdTe surface. We have synthesized antimony t ... [J. Renewable Sustainable Energy 5, 031612 (2013)] published Fri Jun 7, 2013.

Description: M. V. Reddy, P. Babu, K. T. Ramakrishna Reddy, and R. W. Miles Tin sulfide (SnS) thin films were grown by single zone sulfurization process using sputtered tin layers. Metallic tin (Sn) layers were grown on molybdenum (Mo) coated soda-lime glass substrates by DC magnetron sputtering. The sputtered Sn layers along with sulfur flakes were kept in a graphite box a ... [J. Renewable Sustainable Energy 5, 031613 (2013)] published Fri Jun 7, 2013.

Description: Barbara Goss Levi Abstract not available. [J. Renewable Sustainable Energy 5, 032801 (2013)] published Tue Jun 11, 2013.

Description: Zhangxing He, Zhen Li, Zhi Zhou, Feiyue Tu, Yifan Jiang et al. Methylsulfonic acid (MSA) as supporting electrolyte for vanadium redox battery was studied and evaluated by thermal stability test, cyclic voltammetry, linear sweep voltammetry, and charge-discharge technique. The results show that the V(V)-MSA solution has better thermal stability than the sulfuric ... [J. Renewable Sustainable Energy 5, 023130 (2013)] published Fri Apr 5, 2013.

Description: I. Odeh Three years field data analysis for eight systems installed in Jordan is used to determine and investigate photovoltaic (PV), subsystems and system efficiencies of PV water pumping systems. For these three parameters, it is found that all systems inhibit unique trend with insolation. New performance ... [J. Renewable Sustainable Energy 5, 023135 (2013)] published Tue Apr 9, 2013.

Description: Chao Yang, Guogang Yang, Danting Yue, Jinliang Yuan, and Bengt Sunden A 3D model is developed to describe an anode-supported planar solid oxide fuel cell (SOFC), by Ansys/Fluent evaluating reactions including methane steam reforming (MSR)/water-gas shift (WGSR) reactions in thick anode layer and H-O/CO-O electrochemical reactions in anode active layer, coupled with he ... [J. Renewable Sustainable Energy 5, 021420 (2013)] published Wed Apr 10, 2013.

Description: Qian Dai, Shanxu Duan, Tao Cai, and Changsong Chen Renewable energy resources (RESs) with plug-in electric vehicles (PEVs) are being gradually accepted by society for their low carbon emission merits. However, reverse power from the RES will result in the grid node's voltage rise and cause protection malfunction. As large amount of PEVs plug in the ... [J. Renewable Sustainable Energy 5, 021417 (2013)] published Fri Mar 29, 2013.

Description: Jinsheng Xiao, Tingting Zhou, Pierre Benard, and Richard Chahine One of the primary challenges to introduce hydrogen on the energy market is to improve onboard hydrogen storage and research more efficient distribution technologies to increase the amount of stored gas while lessening the storage pressure. The aim of this paper is to study hydrogen storage in an on ... [J. Renewable Sustainable Energy 5, 021415 (2013)] published Fri Mar 29, 2013.

Description: Chunting Liu (刘春廷) , Hongzhou Dong (董红周) , Qian Zhang (张乾) , Qiong Sun (孙琼) , Liyan Yu (于立岩) et al. We report on the synthesis and characterization of Sn-doped hematite nanorods as well as their implementation as the photoanode for solar cells. Hematite nanorods are prepared on fluorine-doped tin oxide (FTO) substrates by a hydrothermal method, followed by a two-step sintering in air, and Sn-dopin ... [J. Renewable Sustainable Energy 5, 021416 (2013)] published Fri Mar 29, 2013.

Description: Hassan M. Farh and Ali M. Eltamaly This paper proposes a variable speed control scheme of grid-connected wind energy conversion system, WECS, using permanent magnet synchronous generator. The control algorithm tracking the maximum power for wind speeds below rated speed of wind turbines (WTs) and ensure the power will not exceed the ... [J. Renewable Sustainable Energy 5, 023125 (2013)] published Wed Apr 3, 2013.