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: The aim of this paper is to present new evidence of relationship between economic activities and environmental conditions, and accordingly to obtain emission-cutting focus in China. This study decomposes total CO 2 emissions into six determinants derived from three net effects of Environmental Kuznets Curve (EKC): scale, technique, and composition. Meanwhile, in views of huge provincial-disparity in economic situation and environmental conditions, we investigate impact factors of CO 2 emissions at sub-national level via generalized method of moment estimation. Test including panel unit root, panel cointegration, Sargan and residual auto-correlation is also performed to maintain strict structure and scientific estimation. Results show that CO 2 emissions substantially increase over a decade with an upward annual growth rate and a high provincial disparity; sorted in descending order, previous CO 2 emissions, coal share, economic growth, and industrial energy consumption are main determinants for accelerated CO 2 emissions; EKC with an inverted-U shape relationship between environment quality and income is not verified. Accordingly, emission-reducing policies at sub-national level are concluded.

Description: The islanding condition occurs when the utility is disconnected and the distributed generation (DG) continues to supply power for local load. This condition is not desirable which brings about the instability of voltage and frequency as well as the power quality degradation, thus presenting a great threaten to maintenance personnel. Considering equipment safety and personnel safety, unintentional islanding for DG operation will not be tolerated here. The study of interference of different islanding detection methods (IDMs) in multi-inverter situations as the potential method has attracted a lot of attention in relevant field. This paper discusses interaction and degradation of three active and positive feedback IDMs, including current-disturbing positive feedback, active frequency drift positive feedback, and Sandia frequency shift IDMs. Non-detection zones of multi-inverter systems in a load parameter space are used as analysis tool. Two 220 V–1 kW Simulink models are set up for the simulation tests and three scenarios with potential for interference and degradation of the system are simulated. Simulation results confirm that multi-inverter equipped with both current and frequency positive feedback disturbing exhibits more complicated phenomenon than the one equipped with single disturbing method.

Description: Although it is possible to improve the optoelectronic conversions of solar cells through the construction of one-dimensional nanostructures on their front surfaces, much effort at such fabrication has led to only modest increases in conversion efficiencies. In this study, we employed i-line lithography and ion implantation to fabricate arrays of well-aligned, contamination-free silicon nanopillars with core/shell p–n junctions for use in high-performance nanostructured solar cells. Such structures provided concurrent improvements in both the optical and electrical characteristics of nanopillar devices. We extracted high currents with large fill factors from these lowly reflective nanopillar arrays, resulting in power conversion efficiencies of up to 11.70 ± 0.22%—that is, 28% higher than that of the planar counterpart. Moreover, when applying 75-nm-thick silicon nitride as a passivation layer on the nanopillars, the average total reflection over wavelengths in the range of 400–1020 nm decreased to 2.56%, while the power conversion efficiency increased further to 12.39%.

Description: This paper presents an innovative technique for energy management of hybrid micro-grid system during grid connected and islanding modes by adaptive power smoothing control. In order to perform the adaptive power smoothing control, fuzzy logic control algorithm (FLCA) is incorporated with conventional control scheme of dc-dc buck boost converter of the battery energy storage system. A standard battery energy limiter is considered with the dc-dc buck boost controller as smoothing trip controller which can disable the smoothing operation if the state of charge of battery (SOC) exceeds its limits. A secondary frequency control and grid resynchronization technique for the converter between the AC and DC buses are considered for islanding and grid reconnected operations, respectively, to demonstrate the effectiveness of the adaptive technique in smoothing wind farm output power. The proposed FLCA adjusts its reference automatically during transition from grid mode to islanding mode and vice-versa based on the battery's SOC. Several cases have been tested where it has been verified that the FLCA can efficiently manage the SOC, while performing smoothing operation and maintain energy balance due to its adaptive nature instead of completely disabling the wind power smoothing at some extreme conditions.

Description: Wind-power ramps are a significant source of uncertainty in wind-energy forecasting and are a challenge to electric-grid stability. In the Canadian province of Alberta, strong westerly winds buffet the Rocky Mountains creating an abundant yet intermittent wind energy resource in the plains of Alberta. In the current study, wind-power ramp events have been detected and correlated to several environmental factors including time-of-day, atmospheric stability, season and a Föhn wind event known locally as a Chinook wind at a field wind measurement station downstream of the Rocky Mountains. Large wind-power ramps (a 50% change in power in less than 4 h) were found to occur on days when a Föhn wind was present over 50% of the time. The result highlights the importance of this meteorological phenomenon to wind energy production locally and also in regions where Föhn winds occur. The detected wind-power ramps were found to vary significantly with season, with the strongest wind-power ramps emanating from the Rocky Mountains in the winter months under stable atmospheric conditions.

Description: Solar global irradiation is barely recorded in remote areas around the world. The lack of access to an electricity grid in these areas presents an enormous opportunity for electrification through renewable energy sources and, specifically, with photovoltaic energy where great solar resources are available. Traditionally, solar resource estimation was performed using parametric-empirical models based on the relationship between solar irradiation and other atmospheric and commonly measured variables, such as temperatures, rainfall, sunshine duration, etc., achieving a relatively high level of certainty. The significant improvement in soft-computing techniques, applied extensively in many research fields, has led to improvements in solar global irradiation modeling. This study conducts a comparative assessment of four different soft-computing techniques (artificial neural networks, support vector regression, M5P regression trees, and extreme learning machines). The results were also compared with two well-known parametric models [Liu and Scot, Agric. For. Meteorol. 106 (1), 41–59 (2001) and Antonanzas-Torres et al ., Renewable Energy 60 , 604–614 (2013b)]. A striking mean absolute error of 1.74 MJ / m 2   day was achieved with support vector regression (around 10% lower than with classic parametric models). Furthermore, the annual sums of estimated solar irradiation with this technique were within the intrinsic tolerance of pyranometers (5%). This methodology is performed in free environment R software and released at www.github.com/EDMANSOLAR/remote for future replications of the study in different areas.

Description: In this study, combustion experiments of green algae granulations ( Enteromorpha clathrata ) (EN) were carried out in a bench-scale fluidized bed. The particle diameter was kept constant during the combustion process and combustion model was described as a shrinking core model. Model was divided into water ball, volatile-matter ball, and carbon ball. Ash ball radius was assumed to be the same during the combustion and carbon ball was burned layer by layer. Simulation of single-particle combustion process consists of process of water evaporation, release of volatile matters and combustion, and the process of char combustion. Finally, a mathematical model was established for the combustion of EN single particle in the fluidized bed, validated by the experiment data. The model can be applied for the design of the combustion devices for the combustion of seaweed particles with high content of ash.

Description: This paper presents a novel probabilistic framework for solving the security constrained generation dispatch problem in the presence of wind power and responsive loads. The proposed framework is capable of decreasing the probability or preventing any constraint violations in real time for different combinations of uncertain variables while minimizing the desired objective functions. The presented framework is formulated as a chance constrained problem using the point estimate method to calculate the probabilistic characteristics of output variables. The objective functions which are studied in this work are total operation costs, emissions, and security indexes. Also a probabilistic multi-objective framework is developed to optimize all objective functions concurrently. To study the effect of responsive loads, two different cases are studied neglecting and regarding demand response resources. The proposed method is studied on the IEEE 30-bus system and the results are presented and compared with results obtained from the deterministic generation dispatch framework.

Description: Traditionally, the economic operation of a microgrid (MG) is independent with that of a distribution network (DN), and the electricity trade between them is simply based on contract prices or wholesale electricity market prices. In order to coordinate the benefits of DNs and MGs more effectively, a new economic operation model for DNs with MG is proposed in this paper modeled as a bilevel programming problem (BLPP). At the upper level, electric power from the gird and electricity price of MGs are control variables. A DN seeks the least operation cost by optimizing these control variables. At the lower level, control variables are electric power of dispatchable distributed generations (DGs) and the DN. Based on the electricity price got from the upper level and the operation costs of dispatchable DGs, a MG minimizes its hourly operation cost by optimizing the control variables. Furthermore, electricity price constraints are considered in this BLPP model, and a method to dynamically determine the constraints is proposed. They are decided by the load power demand profile in the DN and the price differential between the wholesale electricity market and dispatchable DGs. A comprehensive real-time pricing for residential consumers is also considered in the operation model to study the impact from demand response. The proposed BLPP model is solved by particles swarm optimization based on bilevel iterative algorithm. The demonstration is performed on a modified IEEE 33-node radial distribution system.

Description: A new simulation tool aimed at characterizing the thermal behavior of parabolic trough collectors over a wide range of pressures and gas mixtures in the vacuum chamber is presented in this study. The model is able to accurately predict overall efficiency and heat losses obtained in a number of experimental sources based on both on-sun and off-sun testing, with vacuum in the annulus and no hydrogen. Excellent agreement of the simulations with experiments including different gas compositions, especially with high hydrogen concentrations, is achieved through the use of molecular dynamics results for the determination of the accommodation coefficient of the mixture. Additional experiments were carried out to validate the accuracy of the model over a range of pressures between 10 −4 and 130 mbar. The accurate modelling of rarefied gas dynamics presented here also leads to an excellent agreement between simulations and experiments over the whole pressure range. An accurate determination of the performance in such extreme conditions is critical for an adequate Operation & Maintenance strategy, as well as the development of effective predictive and preventives plans.

Description: Study on how renewable energy use and economic growth interact with each other has been an active area of research. This study examines the impacts of renewable energy production (and consumption) on local economic development and income, for a panel data of the 31 provinces of China over the period 2000–2010 within a multivariable framework. Using regression with panels corrected standard errors, this study investigates the effects of renewable energy use on provincial real gross domestic production and local rural income. It is found that deployment of renewable energy use in rural areas has shown significant positive effects on income increase of rural households. But in general, most renewable energy use has negative impacts on economic growth except hydro power generation, improving the economic efficiency of renewable energy production and adjusting renewable energy related subsidy policies are of prime importance.

Description: There is an imperative need of developing new strategies and models for meeting the swelling demand of electricity in developing nations like India. One of the promising models for this would be Decentralized Distributed Generation (DDG). DDG locates the power generating source closer to the consumer utilizing locally available Renewable Energy (RE) resources, thereby decreasing the Transmission and Distribution (T&D) losses. Despite the numerous advantages with DDG, there have been some minor issues preventing its large scale deployment and utilization in India. This paper discusses the various technology options which can be used for DDG in India and the problems which the Indian power sector has been facing for a long time. This paper aims to provide a complete analysis of the best possible RE based technology options for DDG in India along with their cost of generation, benefits, barriers, applications, and the possible pathways for its deployment.

Description: Energy, especially oil, plays a special and irreplaceable role in the economic development, modern civilization, and social progress. With the rapid growth over the past few decades, China has gradually become a big power in oil consumption. In order to solve the contradiction between supply and demand as well as minimize social costs, it is necessary and useful to forecast the trend of China's oil consumption. In addition, reasonable and effective oil production and scheduling through forecasting progress also makes an important impact on the health economic development, social stability, and sustainable development. However, it is a challenging task to carry out such a forecasting because oil consumption is influenced by a number of factors, such as technology development, economic level, government policy, natural disaster, unexpected politic events, and so on. Therefore, it is difficult to forecast such a complex system with a single traditional model. This paper proposes an improved hybrid method known as GGNN, which combined the grey models, the back propagation (BP) neural network, and the genetic algorithm (GA) to take the advantages of linear model, nonlinear model, and swarm intelligence optimization, respectively. GM (1, 1) and improved grey models including an unbiased GM (1, 1), initial correction GM (1, 1), p value GM (1, 1), and background value GM (1, 1)are applied to capture the linear information. BP is widely used due to its nonlinear mapping capability; in this paper, it is used to capture the nonlinear information. Moreover, the GA is also applied to obtain the optimum weights and thresholds of the GGNN which is made up of all grey models and BP neural model. The superiority of this proposed method is examined by using the historical data of China's oil consumption. Assessment results demonstrate that the proposed method GGNN can improve the forecasting accuracy compared with some other existing methods.

Description: The magnitude of energy, which can be extracted by tidal energy converter devices, has a significant impact on the commercial viability of a project. Therefore, a quantitative characterization of the tidal current at the location of interest and subsequently a reliable prediction of the productivity of a tidal energy converter prior to installation is of high interest. This paper presents the successful deployment of a unique and novel fully symmetric tidal in-stream current energy converter HyTide 110-5.3 in Jindo, South Korea, and a methodology to predict the productivity of a single device based on simulation. The simulation combines a 2D shallow water equation model with turbine performance curves and is validated using real performance data from the prototype under real conditions. In addition, the predicted productivity is compared with actual field measurements during the operation of the Voith demonstrator using two Acoustic Doppler Current Profilers according to the IEC specifications for the performance assessment of Tidal Energy Converters, which is novel at that time. The simulation results show that the productivity of a single device can be predicted accurately and furthermore serves as a proof of concept for the symmetrical turbine layout. The 2D shallow water equation solver based on OpenFOAM ® (tidalFoam) captures the rough conditions at the turbine site accurately, where the turbine is facing flood tides with a mean inclined inflow angle of . In addition, the zero-equation turbulence model is shown to successfully capture the influence of a Kármán Vortex street on the turbine unit. High-resolution data of bathymetry, shorelines, and tidal elevations are used to set up the open boundaries of the unstructured mesh used in the model. The sea ground friction as an additional source term in the model is used to calibrate the simulation against Acoustic Doppler Current Profiler measurements on site. The simulation results are shown to be reliable, yielding highly accurate productivity predictions of a single tidal turbine. This is an important step towards a robust commercial evaluation of tidal energy projects prior to installation. Based on the single turbine model, simulations of three tidal current turbine farms as well as the available theoretical and technical power output of the region around Jindo during an entire moon cycle were performed. Possible impacts on average volumetric flow rate changes for neighbouring channels are presented. 30 °

Description: This paper presents the experimental proof of concept of CECO, an innovative wave energy converter designed to convert simultaneously the kinetic and the potential energy of ocean waves into electrical energy, based on the oblique motion of two floating modules. First, the main characteristics of CECO and its work principle are briefly presented. Then, the behavior of the device is analyzed for different wave conditions and modes of operation (power take-off damping levels and device inclinations), based on results obtained with a physical model built on a geometric scale of 1/20. CECO performance strongly depends on the incident wave characteristics, the device inclination angle, and the damping introduced by the power-take-off. Relative capture widths of up to 14% were reached in this initial study, confirming that CECO is a valid technology to extract energy from waves. The application of wavelets showed that CECO response occurs mainly in the frequency of incident waves during the entire test duration.

Description: Many candidate sites for tidal stream energy extraction can be classified as headland sites. Understanding the tidal resource of such sites is of fundamental importance to the industry. This paper examines an upper bound for the power that might be generated from an idealised headland. The dependence of this on length of turbine rows, number of turbine rows, and turbine blockage ratio is examined. Conclusions are drawn from this which are applicable to real headland sites.

Description: Concerns on climate change and dwindling fossil fuel supply have renewed interest on alternative ways of harnessing renewable energy. Using rotating cylinders to generate lift from a fluid stream, a Magnus rotor can produce up to 10 times more lift compared to an airfoil. However, it is also producing more drag. Recent studies have demonstrated improvement on the aerodynamic efficiency of a Magnus rotor through the application of surface modifications such as grooves, bumps, dimples, and even changing the shape of the cylinder into a frustum. However, it is unknown which is most desirable among those modifications; moreover, if some may be combined for even better performance. This present study seeks to fill the mentioned research gap with the aid of computer simulation tool ANSYS CFX. Simulation results showed that modifying cylinder shape into a frustum generates the most lift force. However, it is also increasing the drag on the cylinder. Interestingly, a helical groove may be employed around the frustum cylinder to mitigate the increase in drag, making the two modifications a promising combination. Multiple response surface analysis using desirability function was used to investigate the sensitivity of the rotor design to the different modifications. Furthermore, a new perspective is introduced wherein the rotor may be able to withstand more drag in exchange for more lift. For lift generation purposes, bumps are not desirable. Finally, the aerodynamic performances of the modified rotors are compared against other published results by means of a drag polar plot.

Description: Wave energy converters (WECs) extract energy from ocean waves and have the potential to produce a significant amount of electricity from a renewable resource. However, large “WEC farms” or “WEC arrays” (composed of a large number of individual WECs) are expected to exhibit “WEC array effects”. These effects represent the impact of the WECs on the wave climate at an installation site, as well as on the overall power absorption of the WEC array. Tests have been performed in the Shallow Water Wave Basin of DHI (Denmark) to study such “WEC array effects”. Large arrays of up to 25 heaving point absorber type WECs have been tested for a range of geometric layout configurations and wave conditions. Each WEC consists of a buoy with a diameter of 0.315 m. Power take-off was modeled by realizing friction based energy dissipation through damping of the WECs' motion. The produced database is presented: WEC response, wave induced forces on the WECs, and wave field modifications have been measured. A first understanding of WEC array effects is obtained. This unique experimental set-up of up to 25 individual WEC units in an array layout, placed in a large wave tank, is at present the largest set-up of its kind studying the important WEC array effects. The data obtained from these experimental tests will be very useful for validation and extension of numerical models. This model validation will enable optimization of the geometrical layout of WEC arrays for realistic wave farm applications and reduction of the cost of energy from wave energy systems.

Description: Marine renewable energy (MRE), which includes wave, tidal, and offshore wind energy, has the potential to make significant contributions towards a sustainable energy future in a number of countries worldwide. One such country is Spain, where MREs are among the largest renewable resources; yet they are not playing their full part in the national energy mix. Among other constraints, the lack of a specific policy framework promoting this emerging sector is often pointed to as the main barrier for MRE grid penetration. This paper assesses the Spanish MRE sector, in terms of resource availability, government plans, policy regulations, and projects undertaken, with a view to establish a comparison with the situation in other European countries. In particular, the United Kingdom is used as a case study to analyze ongoing research activities, pilot projects, and lessons learned. As a result, it is found that public funding needs to be increased; the economic crisis should be seen as an opportunity for job creation and industrial development rather than a barrier; administrative procedures must be simplified and cross-national cooperation should be increased. Policies focused on these aspects may contribute to boost the MRE sector in Spain.

Description: Wave power is one of the most rich and promising sources of renewable energy for the future. Approximately 2000 TWh/year can be produced through the exploitation of the wave energy potential. In the past four decades, hundreds of Wave Energy Converters have been proposed and studied, but so far a conclusive architecture to harvest wave power has not been identified. Many engineering problems are still to be solved; these include survivability, durability, and effective power capture in a variable wave climate. Reacting body devices use the inertia of a large mass to generate the reaction needed from the power take off (PTO). Heretically, in the case of a simple inertial mass, optimal control adjusts the dynamic parameters of the PTO, such as the spring constant and energy absorbing damping, to maximize energy absorption. The ISWEC (Inertial Sea Wave Energy Converter) uses a gyroscope to create an internal inertial reaction that is able to harvest wave power without exposing mechanical parts to the harsh oceanic environment. In the past few years, the ISWEC has been successfully tested using two scale models (scales 1:45 and 1:8) and several extensive laboratory experimental campaigns. In this paper, the first full scale ISWEC prototype is presented along with its control system and a refined control strategy. The goal of this paper is to identify an optimal control strategy in order to maximize wave power exploitation of the ISWEC. The control technique presented is numerically applied to the ISWEC full scale device with rated power of 60 kW. The control strategy is tested, and the expected production obtained, for the typical wave climate of Pantelleria Island, in the Mediterranean Sea where the first full scale ISWEC prototype was deployed in autumn 2015.

Description: The recently implemented Longyangxia 320 MW complementary hydro/photovoltaic (PV) project provides a novel operation mode for utility-scale PV power plants. In this paper, the principle of complimentary hydro/PV operation is presented. In short-term scheduling, hydropower can improve the power quality of PV by compensating for the sawtooth-shaped power output curve of PV and for the intermittent and random output of PV. Conversely, in mid- to long-term scheduling and during peak load regulation, PV can compensate the hydro energy deficiency of hydropower via the electricity generated. The concept of virtual hydropower is also proposed. The ability of hydropower to compensate for PV is analyzed, and curtailment situations for solar energy and water as well as their causes are detected. Finally, a calculation model for complementary hydro/PV operation is developed based on the Longyangxia project. The results show that complementary hydro/PV operation can remarkably improve the power quality of PV and is better able to reduce the peak load than a standalone hydropower plant.

Description: The extraction of maximum power from solar photovoltaic (PV) using Maximum Power Point Tracking (MPPT) methods is a promising research area in the recent past. Many methods including conventional methods, such as Hill Climbing and Incremental Conductance, and methods based on neural network, Fuzzy logic and bio-inspired algorithms, were proposed for MPPT application. However, all these methods suffer from drawbacks such as slower convergence, reduced power output, predominant steady state oscillations, larger memory requirement, and complex structure. Hence, in this paper an attempt is made to enhance existing Particle Swarm Optimization technique by emphasizing proper initial value selection. The key features of this method include the ability to track the global peak power accurately under partial shading conditions with almost zero steady state oscillations, faster dynamic response, and easy implementation. Simulations are carried out for different shading patterns and the results obtained are compared with existing methods. Further, simulation results are validated via experimental values.

Description: This study presents full transient numerical simulations of a cross-flow vertical-axis marine current turbine (straight-bladed Darrieus type) with particular emphasis on the analysis of hydrodynamic characteristics. Turbine design and performance are studied using a time-accurate Reynolds-averaged Navier–Stokes commercial solver. A physical transient rotor-stator model with a sliding mesh technique is used to capture changes in flow field at a particular time step. A shear stress transport k-ω turbulence model was initially employed to model turbulent features of the flow. Two dimensional simulations are used to parametrically study the influence of selected geometrical parameters of the airfoil (camber, thickness, and symmetry-asymmetry) on the performance prediction (torque and force coefficients) of the turbine. As a result, torque increases with blade thickness-to-chord ratio up to 15% and camber reduces the average load in the turbine shaft. Additionally, the influence of blockage ratio, profile trailing edge geometry, and selected turbulence models on the turbine performance prediction is investigated.

Description: This paper reports the effects of engine design and operating parameters such as stroke length, ratio of bore to stroke length, compression ratio, equivalence ratio, engine load, biodiesel percentage, friction coefficient, engine speed and mean piston speed on engine performance and energy losses by experiments and a theoretical model based on the finite-time thermodynamics. In this study, the performance of a single cylinder, four-stroke, direct injection diesel engine fueled with diesel-biodiesel mixtures has been experimentally and theoretically investigated. The simulation results agree with the experimental data. After model verification, parametrical studies have been conducted for various conditions. The results showed that the biodiesel percentage and the cycle pressure ratio affect positively the engine performance. The friction coefficient has negative influence on the engine performance. The effective efficiency decreases with the increasing of the engine load, stroke length, and engine speed but effective power increases with increasing them. The effective power always increases with the increasing mean piston speed. However, the effective efficiency decreases at the constant stroke length condition, as it increases at the constant engine speed condition. The effective power and the effective efficiency increase with increasing equivalence ratio to a specified value and then begin to decrease for constant bore/stroke length conditions. The effective efficiency increases with decreasing equivalence ratio as effective power has an optimum value for constant compression ratio condition. The effects of bore/stroke length change at different conditions. At the constant compression ratio condition, the engine performance increases with increasing ratio of bore to stroke length. They are the optimum values which provide the maximum effective efficiency and maximum effective power at the other conditions. This study also reports the energy losses as the ratio of fuel energy and they are classified as friction losses, incomplete combustion losses, heat transfer losses, and exhaust losses. They are defined with respect to compression ratio. With the increasing compression ratio, the friction losses are constant for constant cycle temperature ratio and equivalence ratio, whereas the incomplete combustion losses increase at a constant cycle temperature ratio condition and are constant at constant equivalence ratio condition. The heat transfer losses increase and the exhaust losses decrease for both the conditions. The presented model could be used to optimize the performance of diesel engines fueled with biodiesel and it can be developed for all kinds of engines running at different conditions with various fuels.

Description: In this paper, the energy efficiency of airlines is measured. Number of employees and tons of aviation kerosene are chosen as the inputs. Revenue tonne kilometers, revenue passenger kilometers, and total business income are the outputs. Capital stock is selected as the dynamic factor. A new model, Virtual Frontier Dynamic range adjusted measure (RAM), is proposed to calculate the energy efficiencies of 22 airlines from 2008 to 2012. In Virtual Frontier Dynamic RAM, the reference DMU (decision-making unit) set and the evaluated DMU set are two different sets to distinguish between efficient DMUs. The results demonstrate the following: (1) Air Greenland exhibits the highest energy efficiency, while the efficiency score of Air France-KLM is at the bottom of the 22 airlines. (2) Aggregate airline energy efficiency consistently increased from 2008 to 2012.

Description: A new type of n-p-n transistor photovoltaic device based on CdS/multi-wall carbon nanotube (MWNT)/n-Si configuration was fabricated in a facile process. CdS quantum dots were deposited on fluorine-doped tin-oxide glass using a chemical bath deposition method, and MWNT film was coated on n-type Si substrate by airbrushing. The materials used for the n-p-n transistor solar cells were characterized by multiple techniques including X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman, Ultraviolet visible (UV-vis) spectrophotometer, and I-V characteristic measurements. The CdS layer acts as a good n-type material for the transistor solar cells. The thickness of the CdS layer can be controlled by the chemical bath deposition time to achieve different photovoltaic responses. I-V characteristic measurements show that the efficiency increases with increasing the thickness of the CdS thin layer. Compared with the tandem solar cells based on (p/n)–(p/n) semiconductor junctions, our n-p-n transistor solar cell has a simple structure without using tunnel junctions or wafer bonding schemes for interconnecting the cells.

Description: This study proposes a new method for direct generation of synthetic wind power time series for a wind farm. The method combines the random nature of wind with the operational information of the wind turbines (i.e., failure and repair rates). It uses chronological or sequential Monte Carlo Simulation instead of non-sequential one due to its usefulness and flexibility in preserving statistical characteristics of the chronological processes. The validity of the synthetic values generated by the proposed method and the conventional Markov Chain Monte Carlo methods is compared with the measured data in terms of average and variance values, Probability Distribution Function, and Auto-Correlation Function. Due to increasing interest in the use of the storage system in paralleling with wind power generation, a practical application of the proposed method is also included. Optimal sizing of various energy storage technologies is obtained through a cost-benefit analysis in a typical Micro-Grid.

Description: Food waste along with its two individual components, noodle waste and rice waste, were tested for bio-hydrogen production by using sludge as a source of mix consortia of Clostridium under different physical conditions (pH 5, 6, and 7; temperature 37 °C and 55 °C). The increase in pH increased the bio-hydrogen yield for all tested wastes, whereas an increase in temperature increased the bio-hydrogen yield just for food waste. The highest experimental yield of 115.76 ml/VS removed was produced in the mesophilic noodle waste reactor at pH 7. The drop in pH from 7 to 4.8 ± 0.2 was found optimum for bio-hydrogen production for all tested wastes under mesophilic as well as thermophilic conditions. Most of the hydrogen production was observed within 72 h of incubation, which can be used as the optimum bio-hydrogen production period for food waste. The bio-hydrogen yield, final volatile fatty acids (VFA), and glucose consumption at 72 h were analyzed with the help of the response surface methodology. The resultant plots represented an increase in glucose consumption with the increase in pH from 5 till pH 6 ± 0.5, after which glucose consumption started to decrease up to pH 7. The final VFA represented a similar trend as that observed for glucose except that the change in VFA production was observed due to the temperature and transition was observed at 47.5 ± 1.5 °C for food waste as well as for noodle waste.

Description: A new approach based on the use of external frequency converters for Nd:YAG solar pumped lasers providing effective conversion of solar-to-laser power is proposed. The possibility of a more than four-fold increase in Nd:YAG solar pumped laser efficiency is shown by the simulation calculation method.

Description: This paper uses monthly data for the time span 2006:M01 to 2014:M06, to study the relationship between electricity generation regimes, both ordinary and special, and economic activity in Portugal. An autoregressive distributed lag bounds test approach is pursued to analyse the short- and long-run dynamics between renewable/non-renewable electricity sources and industrial production. Results show that both ordinary thermal sources and hydro sources are driving forces behind electricity from the special regime. Economic activity is stimulating the special regime, but, conversely, the special regime hampers the growth of industrial production. It is demonstrated that a crucial role is being played by large-scale hydropower in accommodating the special regime in the electricity mix. This source is causing economic activity, while at the same time, backing up new renewable sources.

Description: CuZnS is a new promising material in thin film photovoltaics which is earth abundant and eco-friendly. Its electrical and optical properties can be controlled by varying atomic ratios of Copper and Zinc, so as to use it as absorber or window layers. Type of conductivity of this material can also be changed from n to p by adjusting Cu/Zn value. In the present work, we report improvement of cell parameters of CuZnS/In 2 S 3 hetero junction considerably from our own earlier reported values just by increasing Cu to Zn ratio in CuZnS. Current density increased from 5.4 mA/cm 2 to 10.7 mA/cm 2 , thereby enhancing conversion efficiency from 1% to 1.95%. Results are explained on the basis of improvement of multiple band structure.

Description: Lithium iron phosphate (LiFePO 4 ) batteries are widely used as power batteries for electric vehicle applications. For safety issues, it is important to estimate the State of Charge (SOC) of a battery accurately. The improved Thevenin equivalent circuit model is established according to the characteristics of the LiFePO 4 battery, and the model parameters are identified by experimental testing. Furthermore, a novel algorithm of SOC online estimation is proposed, which combines the open-circuit voltage method, ampere-hour integration, and Kalman filtering. The simulations and experimental results show that the improved Thevenin equivalent circuit model can enhance the accuracy of SOC estimation. This proposed algorithm could estimate the SOC precisely even with inaccurate initial values and current measurement errors and distinguish the performances between the batteries. The performance of the proposed SOC estimation method when the voltage sensor is unavailable has been investigated and presented as well. From the characteristics mentioned above, this novel approach is able to guarantee the reliability and safety of the batteries.

Description: The availability of reasonably accurate global solar radiation data is vital for the success of any solar project. However, only a few meteorological stations around the world capture these data as a result of the high cost of measuring equipment and the lack of technical capability in calibrating them. In an attempt to resolve this challenge, engineers and researchers have developed various alternatives to generate the data. In this paper, we surveyed the methods used in generating synthetic global solar radiation with a view to classifying them and bringing out the advantages and the challenges of each. This could motivate the development of a new set of robust prediction techniques that combines the strengths of different existing models for prediction purposes. The various prediction techniques can be generally classified into four categories: the regression techniques, the artificial intelligence methods, the statistical approaches, and the satellite imagery techniques. It is shown from the review that the regression techniques are widely used for the prediction of global solar radiation because of their simplicity. However, their accuracy depends on the completeness of the meteorological data employed in predicting global solar radiation. The statistical methods are based on the assumption that data have an internal linear structure that can be identified and used for prediction purposes. However, it is observed in the literature that the techniques, especially the time series techniques, are generally not good for short time prediction as the error in the prediction of the next value in a series is usually large. Satellite imagery is desirable if surface data for location does not exist. Generally, the use of surface measurements together with a cloud index based on satellite imagery is encouraged to increase the accuracy of prediction. Artificial intelligence methods have been generally favoured for their capability to handle complex relationships between the global solar radiation and the other meteorological data, and as well provide better accuracy and efficiency. This paper is important to engineers and researchers who are interested in the global solar radiation prediction methods.

Description: When the photovoltaic (PV) system is fully illuminated, the voltage-power characteristic of the array has one maximum power point (MPP). This point can be tracked by conventional maximum power point tracker algorithms. On the other hand, in partially shaded PV, the voltage--power characteristic has only one global MPP (GMPP) and multiple local MPPs. It is important to operate the PV system at GMPP for achieving optimal operation. This paper presents the application of two novel meta-heuristic optimization algorithms to extract GMPP from the PV system under partial shading conditions: The mine blast algorithm (MBA) and the teaching learning based optimization algorithm (TLBO). A proposed constrained objective function representing the PV array output power is also presented. Different patterns of shadows that strike the PV array surface are studied. The studied patterns are uniform ones, changing from 0% to 375% with steps of 25%, and non-uniform patterns with different locations of GMPP. The obtained results from each algorithm are compared, and the results show that the MBA based tracker is more reliable, more efficient, and superior to TLBO. A comparison with fuzzy logic control and adaptive neuro-fuzzy and particle swarm optimization based trackers has been done. The results ensure that the reliability of the MBA in solving the problem is addressed.

Description: Aiming at the multiple peaks phenomenon on the power-voltage characteristic curve of photovoltaic (PV) array under partially shaded conditions, this paper proposes a fast global maximum power point tracking method based on sliding mode control (SMC). First, according to the operating characteristics of PV arrays, a reduced scanning range is adopted to avoid large power fluctuations and the optimal scanning direction of global maximum power point (GMPP) is determined to avoid the repeating scanning of the PV curve, both of which reduce the scanning time greatly. Second, during the scanning and tracking process, SMC is introduced to move the operating point quickly to the reference value, which improves the scanning speed further. Finally, when the operating point is close to the GMPP, the control mode is switched from the SMC based tracking control to the SMC based maximum power point tracking control, which quickly stabilizes the operating point of the PV array at the GMPP, reducing the power ripple during steady-state operation. Furthermore, the proposed method is independent of PV parameters, due to the new open circuit voltage detection method proposed in this paper, which does not occupy extra time. Simulation and experimental results validate that the proposed method can guarantee accurate convergence to the GMPP with fast tracking process and low energy loss under partially shaded conditions.

Description: Geothermal heat pumps have several advantages over conventional heating and cooling systems. They can operate in both winter and summer, have high efficiencies, and do not directly emit any greenhouse gases during operation. Investors (in developing countries) can use Clean Development Mechanism as a source of financing for new or existing renewable energy facilities by selling Certified Emission Reductions credits (CERs), which represent the amount of CO 2 emission (1 CER = 1 tCO 2 eq) that is avoided using renewable energy. The aim of this paper is to analyze the possibility of CO 2 reduction by using geothermal heat pumps for fossil fuel displacement with applying Clean Development Mechanism. Results have shown that by using geothermal heat pumps during a 7-year crediting period, the estimated emission reduction would be 79.45 tCO 2 (equal to 80 CERs), enabling the investor to achieve profit from selling 80 CERs and thus helping to fund the proposed project activity. Three main factors which influence the amount of CO 2 reduction have been identified: carbon-dioxide emission factor for electricity source, efficiency of technology used for baseline scenario, and coefficient of performance (COP) of heat pumps.

Description: The utilization of lignocelluloses for biogas production is limited for several aspects, and an efficient pre-treatment is essential to increase the enzyme accessibility of cellulose. This research focused on the mechanism of biogas production and biodegradation properties under the treatments with different acid agents, including sulfuric acid (H 2 SO 4 ), acetic acid (CH 3 COOH), and phosphoric acid (H 3 PO 4 ). The H 3 PO 4 pretreated corn stover was then co-digested with cow dung in a pilot test to investigate the performance of acid pretreatment in practice. The results showed that the main compositions of corn stover were cellulose, hemicellulose, and lignin, and their proportions in the corn stovers were increased after the acid pretreatments. This hence increased the final biogas yields (up to 40.75%), methane content, and promoted the biodegradation process. More significantly, the acid pretreatments delayed the appearance of the peak value of the biogas yield for 3 to 8 days depending on the acid concentrations. This study proposed that the dilute weak acid pretreatment, especially H 3 PO 4 pretreatment, efficiently enhanced the biogas production by increasing the degradation of hemicellulose. Further on, the H 3 PO 4 pretreatment also improved the stability of fermentation, which would benefit the biogas generation in practice. This research contributes to a better understanding of the mechanism of acid influence on enhancing the biogas generation and substrate biodegradation, and provides pratically sound guidance for reclamation of lignocellulosic materials.

Description: A 1 kW e integrated auxiliary power unit (APU) system consisting of an autothermal reformer and a solid oxide fuel cell (SOFC) unit, as well as balance-of-plant components, was designed and analyzed. A relatively easy-to-approach SOFC model was developed in order to conveniently calculate V-I and P-I curves and the system's net efficiency at different operating conditions. The effects of steam to carbon and oxygen to carbon ratios in the reactants, channel dimensions of the SOFC unit, and hydrocarbon fuel types on the integrated APU system's performance were discussed. Five hydrocarbon fuels including diesel, Jet-A, gasoline, ethanol, and methanol were studied as fuel sources for the APU system. The system's net efficiency around 35% is possible for all the tested fuels in the current density range of 100–400 mA/cm 2 . The APU system was also verified to be thermally self-sustainable in the steady state operation by a thermal management analysis.

Description: This study describes a method to quantify the visual impact of an offshore wind farm, as seen from the coast. In brief, the method involves distinguishing between the visual impact due to the intrusion in the observer's vision field and the un-aesthetic effect of the arrangement unevenness. Both parameters, visual intrusion and unevenness, can be quantifiable; therefore, a final indicator for the visual impact of the wind farm can be calculated for a specific wind farm layout. Two approaches are presented to calculate the visual intrusion, which give rise to similar results. The method has been programmed and included in an application that has been tested with two known wind farm layouts, showing a complete coherence of the results given by the method. This method provides the designer with a tool that allows him to take into account the estimated visual impact of a wind farm under study. If an algorithm is used to look for the optimum location/layout for an offshore wind farm, its programmer can include this method in order to obtain a trade-off between maximum profitability and minimum visual impact.

Description: The accuracy and applicability of existing methods of solar resource modelling and solar photovoltaic module performance are investigated in the case of a ground array installation at Edinburgh College, Midlothian Campus, the principal derived quantities consisting of slope irradiation, cell temperature, and cell efficiency. Experimental data were obtained on site through both automated and manual measurements for comparison with the calculated quantities. Results indicate that the horizontal-to-slope conversion models used are extremely accurate, with greater than 99% degree of confidence in the calculated results. Likewise, correlations between measured and calculated cell temperature were very high at up to 94%. Estimations of the cell efficiency and hence module output were less reliable, however, with only one of the models used, for one of the days studied, giving reasonable results. Efficiency values were, however, in the approximately correct range of 15%–20%.

Description: Algae, an ideal feedstock for biodiesel, can assimilate organic and inorganic pollutants of animal wastewater and convert them into cellular constituents such as lipids and carbohydrates. In the study, the impacts of Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) of swine manure wastewater and inoculation concentration of algae seeds on biomass production of algae Chlorella sorokiniana were studied. Our results demonstrated that concentration of TN in wastewater would scarcely affect the algae growth, and inhibition of ammonia nitrogen (NH 3 -N) on the growth of C. sorokiniana was not so obvious, although NH 3 -N occupied the overwhelming proportion of nitrogen source. Three factors (COD, TP, and inoculation size) which had significant impact on biomass production of C. sorokiniana using swine manure wastewater were optimized using response surface methodology. The optimal biomass production (128 mg l −1 d −1 ) was obtained when C. sorokiniana was cultivated in swine manure wastewater containing 345 mg l −1 COD and 45 mg l −1 TP, with the initial inoculation concentration of 136 mg l −1 algae seeds (dry weight). Then the strain was cultivated in 30 l photobioreactor with the optimized condition, a biomass yield (160 mg l −1 d −1 ) was achieved, accompanied with removal rates of TN (72%), TP (86%), and COD (38%). The study could provide guidance for large-scale cultivation of algae in wastewater.

Description: We address the problem of setting realistic regional carbon reduction targets in China. Scenario analysis, combined with a regional carbon emission model, was used to evaluate whether the current government goals are realistic. We first set reasonable scenarios for factors in the model that have important effects on carbon emissions, and then forecast the carbon emissions for a given region. Reasonable regional carbon reduction goals were obtained based on these forecasts. In Beijing, eleven kinds of development scenarios were considered, and their effects on carbon reduction goals were analyzed. Results showed that future CO 2 emissions in Beijing will rise markedly, whereas carbon intensity will reduce gradually, causing the rate of carbon reduction to slow over the long term. We found that an 18% reduction in carbon intensity for Beijing during the 12th Five-Year Plan is a reasonable goal, whereas a 45%–50% reduction from 2005 to 2020 is also realistic. Moreover, the carbon intensity in Beijing could be reduced by 12%–16% during the 13th Five-Year Plan and by a further 12% during the 14th Five-Year Plan. Rapid economic growth, stable urban development, and a rising proportion of tertiary industries in Beijing all contribute to achieving its carbon reduction target.

Description: Bio-energy from lignocellulosic biomass is cleaner, sustainable, and one of the renewable energy sources that could help meet some of our energy demand. Unlike fossil fuels, it can be grown and used repeatedly and its use can replace the fossil fuels. In addition to this, these materials are easily available either in the form of agricultural waste or forest residues and are economically viable. The current study focuses on physico-chemical characterisation of three commonly available lignocellulosic biomasses of north-east India such as Castor ( Ricinus communis ), Jatropha ( Jatropha curcas ), and Miscanthus ( Miscanthus sinensis ) for second generation biofuels production. Ultimate analysis (CHNSO), thermogravimetric analysis, X-ray diffraction, Fourier transformation infrared (FTIR), and oxygen bomb calorimeter techniques were used to characterise the above mentioned three lignocellulose biomasses. It was found that the cellulose content of three biomasses varied from 40% to 44%, hemicellulose content from 8% to 14%, and lignin content varied from 21% to 30%. Chemical structure of lignocellulose is studied through FTIR. The crystallinity index of Castor and Jatropha is similar, i.e., ∼69%, where as crystallinity index of Miscanthus was 72%. Due to the presence of higher carbon and cellulose content along with less moisture (10%–12%), ash (5%–10%), sulphur (0.1%–0.8%), and extractives (12%–20%) make them a very good source for production of alcoholic fuels through a biochemical route.

Description: Solar power is fundamentally very intermittent. The majority of the power is produced when the sun is shining brightly and is significantly reduced during substantial cloud cover and dust settlement. As solar Photovoltaic (PV) sources grow in use and the percentage of grid power met by them increases, grid stability becomes an increasingly important issue. In principle, the usage of an energy storage at the solar farm would reduce the effects of intermittency. However, batteries which are commonly used for storage of DC power are not a suitable option with intermittent power sources due to their high cost and low lifetimes (2000–3000 cycles). Supercapacitors have excellent power and cycling capabilities (100 000 cycles) make them ideal for storing and discharging energy from intermittent sources. They can be easily integrated with individual solar panels, offering an attractive option to reduce intermittency right at the panel level. In this paper, simulations have been carried out to understand the effect of intermittency on the PV system performance and it was found that the power output drastically decreases due to intermittency. Simulations show that a 50% solar shading causes a 50%–60% loss in solar power output. To manage the intermittency, we have designed and built two systems (Model 1 and Model 2) where a supercapacitor is being used as the storage element and is directly connected to the solar panels. The first model uses a simple relay based switching for reducing intermittencies. However, it is not efficient under all shading intermittencies. The second model uses a semiconductor switching integrated with dynamic threshold limiter which works successfully in all types of intermittencies for a period of 45 to 75 s (with a minimal switching time of 40 ms). The system proposed here is easily scalable to accommodate higher storage requirements.

Description: The U.S.-China EcoPartnership for Environmental Sustainability (USCEES), one of 30 EcoPartnerships, was established within the U.S.-China Strategic Economic Dialogue framework in May 2011 by a joint agreement between the U.S. Department of State and China's National Development and Reform Commission. The USCEES has the goal of fostering bi-national research innovation, communication, and entrepreneurship to address the interconnected challenges of environmental, social, and economic sustainability. Research and education programs within the USCEES are focused on understanding current and past degradation of natural resources, investigating the drivers, impacts, and mitigation of global climate change, and assessing options for sustainable use of natural resources. Although both the U.S. and China have embraced a future based on science, technology, and innovation, our bi-national framework acknowledges that these two nations have vastly different cultural, political, and demographic legacies that could pose distinct challenges to uniform solutions or mandated collaborative networks. The peer-to-peer connections that drive the research component of the USCEES program are promoted and initiated from the ground up; they are based on the voluntary participation of scientists and engineers who are fascinated by the intellectual challenge of solving complex problems of inherent interest to them. Herein, we present highlights of USCEES activities that describe our efforts to discover, incubate, and nurture U.S.-China research collaborations to meet our collective goals. We discuss our pilot programs that are designed to highlight university facilities, resources, and technologies for tech transfer and licensing with an environmental solutions-oriented direction. Additionally, programs to promote cross-EcoPartnership collaborations are discussed.

Description: Uncertainties in smart distribution grids operation are important and challenging issues. The integration of the renewable energy resources (RERs) into the conventional distribution networks changes the radial structure of the network while its inherent characteristics such as high R/X ration of feeders remained unchanged. Conventional power flow methods may be not be suitable or efficient for smart distribution networks. This paper proposes a heuristic optimization based Probabilistic Load Flow (PLF) method to overcome new problems of future distribution networks. The proposed algorithm is suitable for any smart distribution networks with RERs. Imperialist Competitive Algorithm is used to formulate and solve the PLF considering RERs. Comparative studies with small and large sample numbers of RERs and load data are done to evaluate the effect of the samples number on the performance and simulation time. The results are compared with Monte Carlo Simulation (MCS) method. Some network parameters such as buses voltage, feeders power, and network loss in modified 33-bus network are given as Probability Density Function and compared by MCS. Based on the results the proposed algorithm can solve the PLF, regardless of the type of distribution network.

Description: New York Institute of Technology, Peking University, Wuhan University, the International Society for Water Solutions of the American Institute of Chemical Engineers, and an industrial partner HDR|HydroQual formed an EcoPartnership in 2013. The partners are jointly advancing innovative water quality models, real-time water monitoring tools and information systems, water scarcity and hydrologic simulations, and techniques for water management during hydraulic fracturing. These goals are being pursued through a combination of pilot demonstration projects, research on the next generation of technologies, and practical training and community outreach (through conferences and workshops). This comprehensive approach will help foster water quality, management, and conservation in China and the U.S.