Showing papers on "Solar power published in 2018"

Solar energy: Potential and future prospects

Abstract: The development of novel solar power technologies is considered to be one of many key solutions toward fulfilling a worldwide increasing demand for energy. Rapid growth within the field of solar technologies is nonetheless facing various technical barriers, such as low solar cell efficiencies, low performing balance-of-systems (BOS), economic hindrances (e.g., high upfront costs and a lack of financing mechanisms), and institutional obstacles (e.g., inadequate infrastructure and a shortage of skilled manpower). The merits and demerits of solar energy technologies are both discussed in this article. A number of technical problems affecting renewable energy research are also highlighted, along with beneficial interactions between regulation policy frameworks and their future prospects. In order to help open novel routes with regard to solar energy research and practices, a future roadmap for the field of solar research is discussed.

A Comprehensive Review of Thermal Energy Storage

Abstract: Thermal energy storage (TES) is a technology that stocks thermal energy by heating or cooling a storage medium so that the stored energy can be used at a later time for heating and cooling applications and power generation TES systems are used particularly in buildings and in industrial processes This paper is focused on TES technologies that provide a way of valorizing solar heat and reducing the energy demand of buildings The principles of several energy storage methods and calculation of storage capacities are described Sensible heat storage technologies, including water tank, underground, and packed-bed storage methods, are briefly reviewed Additionally, latent-heat storage systems associated with phase-change materials for use in solar heating/cooling of buildings, solar water heating, heat-pump systems, and concentrating solar power plants as well as thermo-chemical storage are discussed Finally, cool thermal energy storage is also briefly reviewed and outstanding information on the performance and costs of TES systems are included

A comprehensive review of state-of-the-art concentrating solar power (CSP) technologies: current status and research trends

Abstract: Concentrating solar power (CSP) has received significant attention among researchers, power-producing companies and state policymakers for its bulk electricity generation capability, overcoming the intermittency of solar resources. The parabolic trough collector (PTC) and solar power tower (SPT) are the two dominant CSP systems that are either operational or in the construction stage. The USA and Spain are global leaders in CSP electricity generation, whereas developing countries such as China and India are emerging by aggressive investment. Each year, hundreds of articles have been published on CSP. However, there is a need to observe the overall research development of this field which is missing in the current body of literature. To bridge this gap, this study 1) provides a most up-to-date overview of the CSP technologies implemented across the globe, 2) reviews previously published review articles on this issue to highlight major findings and 3) analyzes future research trends in the CSP research. Text mining approach is utilized to analyze and visualize the scientific landscape of the research. Thermal energy storage, solar collector and policy-level analysis are found as core topics of discussion in the previous studies. With a holistic analysis, it is found that direct steam generation (DSG) is a promising innovation which is reviewed in this study. This paper provides a comprehensive outlook on the CSP technologies and its research which offers practical help to the future researchers who start to research on this topic.

Potential of solar energy in developing countries for reducing energy-related emissions

Abstract: The growing global demand for energy from fossil fuels plays a key role in the upward trend in greenhouse gas (GHG) emissions and air pollutants. Rapid population growth and increasing energy demand in the developing countries have brought many concerns such as poverty, pollution, health and environmental problems. While for these countries, particularly the poorest ones, modern energy is necessary to stimulate production, income generation and social development plus reduce the serious health issues that are caused by the use of fuelwood, charcoal, animal dung and agricultural waste. Solar energy is the best answer to energy poverty and it can provide excellent opportunities for reduction of GHG emissions and indoor air pollution through substituting kerosene for lighting and firewood for cooking. Solar photovoltaic (PV) can be an appropriate technology for a source of renewable electricity in developing nations especially in remote rural areas where grid extensions are financially or technically not viable. PV can also be used to reduce demand for fossil fuels and associated emissions, including carbon dioxide (CO2), nitrogen oxides (NOx) and sulfur dioxide (SO2). The use of PV systems can reduce 69–100 million tons of CO2, 126,000–184,000 t of SO2 and 68,000–99,000 t of NOx by 2030. In case countries use concentrating solar power (CSP) systems, each square meter of concentrator surface is enough to save about 200–300 kg (kg) of CO2 emissions annually. Although there are excellent renewable opportunities in many developing countries, several key barriers have prevented large-scale deployment of solar energy technologies in these countries. This study reviews the sources of energy-related emissions, risks of climate change, global solar energy potential, sustainability indicators of renewable energies, environmental impacts of fossil fuels and renewable energies, benefits of solar energy utilization. It also discusses barriers to widespread use of solar energy.

Wind and Solar Power Integration in Electricity Markets and Distribution Networks Through Service-Centric Virtual Power Plants

Abstract: A virtual power plant (VPP) is formulated and developed as a service-centric aggregator that enables the market integration of distributed energy resources and simultaneously supports cooperation with the distribution system operator in addressing the issue of network usage A suitable schedule of interactions and communications between aggregators, market operators, system operators, generators, and consumers, regarding electricity market participation and network operation is proposed and presented in a sequence diagram The cooperation on congestion management in the distribution network is highlighted as a solution to relieve network constraints via the optimal adjustment of active and reactive power of VPP resources while maximizing renewable energy integration across the pool under management The VPP reduces uncertainty affiliated with input data by employing the latest forecasts through a rolling horizon approach in the planning stage Thanks to the flexibility of the VPP to perform rescheduling in accordance with agreements it negotiated with its resources, it becomes possible to refrain from undesirable curtailments Both the market-integrative and the service-centric roles of the VPP are verified through modeling and simulation with a benchmark European distribution network The results confirm the added value of the proposed VPP in enhancing the integration of wind and solar power

Energy and exergy analyses of various typical solar energy applications: A comprehensive review

Abstract: The overuse of fossil fuels in real life applications has caused their rapid depletion and fast climate change due to global warming and thus access to eco-friendly energy resources has become essential to meet the growing demand of clean energy. With this view, solar energy has proven to be an effective alternative and clean source of energy for the sustainable development of the society worldwide. Solar energy is a cheap, abundant and everlasting source of renewable energy and thus it can be integrated with different systems deals with energy consumption to overcome the dependency of present society on conventional fuels. Such integration of solar energy has given an opportunity for several studies based on the energy and exergy approaches. The energy analysis is very crucial in the study of process effectiveness while the exergetic analysis is another important tool to investigate the realistic behaviour of process involving various energy losses and internal irreversibility. The main objective of this article is to bring out valuable recommendations for wide exploitation of solar energy systems for different applications, from a thermodynamics perspective. Therefore, the present article has summarized the previous findings on energy and exergy analyses of different solar energy systems (solar drying, solar air conditioning and refrigeration, solar water heating, solar cooking and solar power generation through solar photovoltaic and concentrated solar power techniques used for various heat and power generation applications).

Solar energy forecasting based on hybrid neural network and improved metaheuristic algorithm

Abstract: Prediction of solar power involves the knowledge of the sun , atmosphere and other parameters, and the scattering processes and the specifications of a solar energy plant that employs the sun's energy to generate solar power . This prediction result is essential for an efficient use of the solar power plant, the management of the electricity grid, and solar energy trading. However, because of nonlinear and nonstationary behavior of solar power time series, an efficient forecasting model is needed to predict it. Accordingly, in this paper, we propose a new forecast approach based on combination of a neural network with a metaheuristic algorithm as the hybrid forecasting engine. The metaheuristic algorithm optimizes the free parameters of the neural network. This approach also includes a 2‐stage feature selection filter based on the information‐theoretic criteria of mutual information and interaction gain, which filters out the ineffective input features. To demonstrate the effectiveness of the proposed forecast approach, it is implemented on a real‐world engineering test case. Obtained results illustrate the superiority of the proposed approach in comparison with other prediction methods.

Recent advancements and challenges in Solar Tracking Systems (STS): A review

Abstract: The conversion of solar energy into electricity is a viable response to address most of world's energy problems. Among the parameters affecting the performance of both photovoltaic (PV) cells and concentrating solar power (CSP) systems include their orientation and tilt angle with respect to the sun. Solar trackers (ST) are ideal devises for efficiency improvement. This paper aims to review the most commonly used ST and identify the systems that offer benefits such as greater efficiency, greater tracking accuracy, easy installation and cost effectiveness. There are mainly two types of ST viz. single and double axis ST. The optimization of these devices requires cumbersome specifications to avoid potential tracking errors that often lead to their poor performance. These specifications cannot be fulfilled by simple tracking methods due to different sources of tracking errors such as the misalignment of the tracking fixture, the level of pollution of the area, the shading of the sensors, the types of control schemes involved, the auxiliary units of the system, the lack of maintenance as well as the imperfection and power mismatch of connecting grids. The study reveals that double axis ST in form of polar-axis and azimuth/elevation featuring the solar movement models and the dynamic closed loop feedback control are the most effective and generally give more than a 40% improvement in energy return compared to fixed PV panels. Moreover, large systems significantly reduce the costs and save on materials. The energy consumed by the moving fixtures is mostly low (2–5% of the collected energy) but this could be higher if no optimization is performed. Lastly, all the hardware and software energy saving parameters must be optimized right from the early stages of the development of the system to prevent materials wastage and the energy over-consumption by the tracking units.

Fundamentals of soiling processes on photovoltaic modules

Abstract: The topic of soiling of photovoltaic module (PV) and concentrated solar power (CSP) collectors has recently gained increasing attention due to its impact on solar power production, especially in arid and semi-arid areas with high concentrations of airborne dust. Soiling describes the deposition of dust and other contaminants on surfaces, reducing solar irradiation by absorbing or reflecting the sunlight, causing energy yield losses which can exceed 1% per day. The amount of soiling is influenced by complex interactions of many factors which can vary significantly from site to site. In this study we provide a detailed overview of macroscopic and microscopic factors influencing soiling. This includes a global analysis of key parameters including airborne dust concentrations, dust characteristics (mineral composition, size distribution), and particle deposition rates. A theoretical model for relevant particle adhesion and removal forces is presented to achieve a microscopic understanding of wind cleaning effects. Further, it was found that dew occurs frequently on PV modules in many soiling affected areas and that this can significantly increase particle adhesion. Therefore, a detailed analysis and model of the dew-driven soiling mechanisms of cementation, particle caking, and capillary aging are given on the basis of microstructural material and dust characterization of outdoor exposed glass samples. Furthermore, we study the complex interplay and dynamics of different environmental parameters (relative humidity, ambient and module temperature, airborne dust concentration, wind speed) and their correlation to dust accumulation, and provide explanations with the help of the developed models. Overall the study aims to provide a useful, in-depth but also global overview and fundamental understanding of soiling processes on PV modules down to the microscale, which could be used to develop appropriate soiling mitigation strategies.

The Role of Concentrating Solar Power Toward High Renewable Energy Penetrated Power Systems

Abstract: Achieving high renewable energy penetrated power systems requires considerable operational flexibility to hedge the variability and uncertainty of variable renewable energy (VRE) generation. Compared with VRE sources, concentrating solar power (CSP) is an emerging controllable renewable generation technique that utilizes solar thermal power to generate electricity. The operational dispatchability of CSP would contribute to the power system transition toward high renewable penetration. In this paper, we explore how the generation portfolio will change toward high renewable energy penetrations, how much cost is involved, and what role CSP will play in realizing a high renewable energy penetrated power system. This study relies on a stochastic two-stage generation and transmission expansion planning model with CSP plants. The model captures the uncertainty and variability of renewable generation and the flexibility limits of thermal plants. With the target of achieving a renewable-dominated minimum-cost system with an expected renewable energy penetration level, the investments of both generation and transmission facilities are optimized. A case study on IEEE test systems with renewable technology cost data in 2050 is performed to analyze the value of CSP toward high renewable energy penetrated power systems.

Energy Harvesting Sources, Storage Devices and System Topologies for Environmental Wireless Sensor Networks: A Review.

Abstract: The operational efficiency of remote environmental wireless sensor networks (EWSNs) has improved tremendously with the advent of Internet of Things (IoT) technologies over the past few years. EWSNs require elaborate device composition and advanced control to attain long-term operation with minimal maintenance. This article is focused on power supplies that provide energy to run the wireless sensor nodes in environmental applications. In this context, EWSNs have two distinct features that set them apart from monitoring systems in other application domains. They are often deployed in remote areas, preventing the use of mains power and precluding regular visits to exchange batteries. At the same time, their surroundings usually provide opportunities to harvest ambient energy and use it to (partially) power the sensor nodes. This review provides a comprehensive account of energy harvesting sources, energy storage devices, and corresponding topologies of energy harvesting systems, focusing on studies published within the last 10 years. Current trends and future directions in these areas are also covered.

Energy production, economic growth and CO 2 emission: evidence from Pakistan

Abstract: An extensive body of knowledge is available on the relationship between energy consumption and CO2 emission incorporated by different variables. However, the role of energy production in the pollution equation is largely unknown. The present work quantifies the relationship between energy production, economic growth and CO2 emission. A family of econometric tools is used to achieve the objective of the study. Due to the sensitivity of objective of the present work, we use structural break unit root test to measure the stability of parameters within the time span of 1970–2011. Johansen cointegration test confirms the existence of cointegration among variables. Autoregressive distributive lag model reveals that energy production from the fossil fuel is the main culprit behind growing CO2 emission. Additionally, the finding of the study claims the existence of environmental Kuznets curve hypothesis in the significance of energy production in Pakistan. Moreover, bidirectional causality is detected between energy production and carbon dioxide emission in the long-run path. It is suggested that pollution can be condensed by producing energy from the renewable source (hydropower, solar power, geothermal and wind energy) and add more renewable energy to the energy mix.

The road ahead for solar PV power

Abstract: Over the past decade, solar photovoltaic (PV) power has experienced dramatic deployment growth coupled with substantial decreases in system prices. This article examines how solar PV power is currently positioned in the electricity marketplace and how that position is likely to evolve in the foreseeable future. We first assess the current cost competitiveness of solar PV in select U.S. locations and industry segments using the levelized cost of electricity (LCOE) metric. This framework enables us to quantify the effects that supportive public policies, time-of-use pricing, and anticipated future technological improvements have on the cost of solar PV. We also build on recent analytical work that has identified circumstances under which it becomes financially attractive to add behind-the-meter batteries to an existing PV solar system. Taken together, our findings suggest that solar power, by itself and in conjunction with low cost storage, is positioned to account for a significant and growing share of the overall energy mix.

Materials corrosion for thermal energy storage systems in concentrated solar power plants

Abstract: The current commercial deployment of concentrating solar power (CSP) relies on a system of thermal energy storage (TES) for round the clock generation of electricity. The heat harvested by a system of collectors, either parabolic troughs or a heliostat field, is transferred by means of heat transfer fluid (HTF) to a storage tank, where it is kept until required for power generation. In the implemented systems, the storage of heat is accomplished by a mixture of salts characterized by an optimum set of properties required at the desired temperatures of operation. In liquid phase, the salt mixture represents an ionic conductor providing conditions for electrochemical degradation of materials when in direct contact. The risk of materials failure is further increased by thermal cycling and the possibility of mechanical stress. This paper describes the possible corrosion issues that might affect a TES system considering generalized and localized corrosion, as well as flow accelerated and mechanically assisted corrosion for the specific operation conditions of CSP plants. A comprehensive summary of uniform corrosion rates determined for common and less common alloys considered for application in TES is provided, along with discussion of the applicability for evaluation of possible corrosion damage in an actual CSP plant.

Design and Control of Microgrid Fed by Renewable Energy Generating Sources

Abstract: This paper presents a control of a microgrid at an isolated location fed from wind and solar based hybrid energy sources. The machine used for wind energy conversion is doubly fed induction generator (DFIG) and a battery bank is connected to a common dc bus of them. A solar photovoltaic (PV) array is used to convert solar power, which is evacuated at the common dc bus of DFIG using a dc–dc boost converter in a cost effective way. The voltage and frequency are controlled through an indirect vector control of the line side converter, which is incorporated with droop characteristics. It alters the frequency set point based on the energy level of the battery, which slows down over charging or discharging of the battery. The system is also able to work when wind power source is unavailable. Both wind and solar energy blocks have maximum power point tracking (MPPT) in their control algorithm. The system is designed for complete automatic operation taking consideration of all the practical conditions. The system is also provided with a provision of external power support for the battery charging without any additional requirement. A simulation model of system is developed in MATLAB environment and simulation results are presented for various conditions, e.g., unavailability of wind or solar energies, unbalanced and nonlinear loads, and low state of charge of the battery. Finally, a prototype of the system is implemented using a 5-kW solar PV array simulator and a 3.7-kW wound rotor induction machine and experimental results are produced to reaffirm the theoretical model and design.

Overview of porous media/metal foam application in fuel cells and solar power systems

Abstract: Fuel cells and solar energy are promising candidates for electricity generation. It is forecast that fuel cells and solar power systems will play an important role in reducing the greenhouse gas footprint and replacing fossil fuels. Therefore, the limitations of fuel cells and solar power systems, such as low efficiency, high cost, and low reliability, must be addressed appropriately to enable their full potentials. Metal foam is a new class of material that has gained immense attention due to its excellent properties suitable for a wide range of applications. Its unique characteristics distinguish it from typical solid metals. The properties of metal foam can be modified during the fabrication stage by manipulating its physical structure. The goal of this paper is to review the application of metal foam in fuel cells and solar power systems. Besides, the performance of metal foam in fuel cells and solar systems is also discussed. Metal foam has been applied to the electrodes, gas diffusion layer and flow field of fuel cells to enhance performance, especially in regard to current density and flow distribution. Furthermore, metal foam is a heat exchanger for the solar energy harvesting system to improve its efficiency. Superior performances in experimental testing allows the possibility of commercialization of metal foam products in the renewable energy field.

Forecasting Solar Power Using Long-Short Term Memory and Convolutional Neural Networks

Abstract: As solar photovoltaic (PV) generation becomes cost-effective, solar power comes into its own as the alternative energy with the potential to make up a larger share of growing energy needs. Consequently, operations and maintenance cost now have a large impact on the profit of managing power modules, and the energy market participants need to estimate the solar power in short or long terms of future. In this paper, we propose a solar power forecasting technique by utilizing convolutional neural networks and long–short-term memory networks recently developed for analyzing time series data in the deep learning communities. Considering that weather information may not be always available for the location where PV modules are installed and sensors are often damaged, we empirically confirm that the proposed method predicts the solar power well with roughly estimated weather data obtained from national weather centers as well as it works robustly without sophisticatedly preprocessed input to remove outliers.