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[en] Highlights: • A novel methodology to estimate global wind energy potential is proposed. • Wind park suitability is constrained by land use and water depth. • Power production density is derived from energy conservation laws. • Maximum wind potential is dependent on minimum Energy Return on Investment. • Total potential is established between 700 and 100 EJ/year at EROImin from 5 to 12. - Abstract: Looking ahead to 2050 many countries intend to utilise wind as a prominent energy source. Predicting a realistic maximum yield of onshore and offshore wind will play a key role in establishing what technology mix can be achieved, specifying investment needs and designing policy. Historically, studies of wind resources have however differed in their incorporation of physical limits, land availability and economic constraints, resulting in a wide range of harvesting potentials. To obtain a more reliable estimate, physical and economic limits must be taken into account. We use a grid-cell approach to assess the theoretical wind potential in all geographic locations by considering technological and land-use constraints. An analysis is then performed where the Energy Return on Investment (EROI) of the wind potential is evaluated. Finally, a top-down limitation on kinetic energy available in the atmospheric boundary layer is imposed. With these constraints wind farm designs are optimized in order to maximize the net energy flux. We find that the global wind potential is substantially lower than previously established when both physical limits and a high cut-off EROI > 10 is applied. Several countries’ potentials are below what is needed according to 100% renewable energy studies.
[en] Highlights: • Thermodynamic analysis is presented for a LAES system combined with packed bed units. • The LAES system round-trip efficiency is in the range 50–62%. • Cold box inlet temperature and discharge pressure have significant influence on system performance. • LAES system has smaller air storage volume and higher ASED compared with A-CAES system. - Abstract: Energy storage is a key technology required to manage intermittent or variable renewable energy, such as wind or solar energy. In this paper a concept of an energy storage based on liquid air energy storage (LAES) with packed bed units is introduced. First, the system thermodynamic performance of a typical cycle is investigated and temperature distribution in cold boxes is discussed. Then, the effects of inlet temperature of cold boxes, charge and discharge pressures on thermal behaviors of LAES system are analyzed, as well as the system round-trip efficiency. Finally, an overall comparison between this LAES system and an adiabatic compressed air energy storage (A-CAES) system is conducted. The system could achieve a round-trip efficiency in the range 50–62% depending on the values of process conditions. The system round-trip efficiency decreases with the increase of cold box inlet temperature, and increases with the rise of charge and discharge pressures. Although the round-trip efficiency of the present LAES system is a bit lower than the A-CAES system, however, the air storage volume decreases and the air storage energy density (ASED) increases remarkably for the same operational conditions. The main conclusions draw from this work is beneficial for future LAES development in particular the combination with the packed bed units and the fit with the requirements for large-scale energy storage.
[en] India is blessed with good solar resources and many regions of the country receive above-average sunshine compared to other regions of the world. The primary technology used for harnessing and converting solar energy into electrical energy in India is based on photovoltaic (PV) cells. Concentrated solar power (CSP) has hardly contributed to the overall installed solar power capacity in the country. In this article, some of the challenges that have inhibited the growth of CSP are identified and possible solutions suggested. The critical challenges for CSP are related to the lack of reliable direct normal irradiance database, indigenous manufacturing and competition from PV. The results of a case study carried out to assess the impact of indigenous manufacturing and economies of scale on capital costs and levelized cost of electricity are presented. This study shows that even with indigenous manufacturing and considering economies of scale, the capital cost per MW (Megawatt) of installed capacity is higher than the Central Electricity Regulatory Commission benchmark costs. To initiate larger adoption of CSP in India, we may have to consider alternative configurations, such as coupling desalination or thermal cooling systems to a CSP power plant. The merits of such configurations, called poly-generation plants, are presented for the Indian scenario. (author)
[en] Energy storage must play a crucial role in the widespread adoption of renewable energy sources because they are intermittent. In addition, energy storage is also important in matching the electrical power load with the generation capacity to improve the overall power plant efficiency. This point has been recognized in the recent California state mandate for the electrical utility companies to have energy storage at each power plant in order to utilize their generation capacity more efficiently. While electrochemical energy storage is still very expensive, thermal energy storage can be cost effective even at the present commercial development level, especially for solar CSP plants and conventional thermal power plants. Use of phase change materials for thermal energy storage can increase the storage density, reduce the size and therefore reduce the costs even further. However, it presents certain challenges in terms of poor heat transfer and material compatibility issues. This presentation will describe how these challenges have been overcome by innovative and transformative solutions to develop thermal energy storage using phase change materials at a system cost of less than $15/kWhth as compared to the present commercial thermal energy costs of more than $30/kWhth. (author)
[en] This preliminary study investigated data mining-based methods to assess and predict the performance of geothermal heat pump(GHP) system. Data mining is a key process of the knowledge discovery in database (KDD), which includes five steps: 1) Selection; 2) Pre-processing; 3) Transformation; 4) Analysis(data mining); and 5) Interpretation/Evaluation. We used two analysis models, categorical and numerical decision tree models to ascertain the patterns of performance(COP) and electrical consumption of the GHP system. Prior to applying the decision tree models, we statistically analyzed measurement database to determine the effect of sampling intervals on the system performance. Analysis results showed that 10-min sampling data for the performance analysis had highest accuracy of 97.7% over the actual dataset of the GHP system.
[en] The paper presents the results of calculated research on determining the thermal technical indicators of a combined solar desalinization and drying plant. The structure of the plant is developed and proposed. A mathematical model is developed that describes the thermal processes occurring in the plant based on heat-balance equations solved using the Laplace method.
[en] India faces a major challenge in providing a long-term energy security needed for meeting the aspirations of her growing population and, at the same time, in fulfilling her commitments for preventing generation of greenhouse gases. Use of non-fossil energy sources is the solution. There is a need for making a right balance of generation of energy from sources such as solar and wind which are, by nature, distributed and intermittent and from nuclear which is concentrated and continuous. It will be highlighted in this presentation how the solar and nuclear energy – the two primary energy sources can complement each other in supplying energy in a sustainable manner
[en] Pakistan has been struggling to overcome its energy deficiency issues for quite some time due to its extraordinary energy problems including heavy reliance on costly imported furnace oil, depleting natural gas reserves, severe power outages, high line-losses, etc. However, the efforts directed towards finding alternative, effective and lasting energy solutions are more intensive now than ever before. Renewable energy resources found in abundance in Pakistan, including solar, wind and biomass, have huge technical potential to meet the energy requirements. Present study is based on inputs from energy experts through a survey, prioritize various renewable energy resources taking into account factors including environmental impact, efficiency, cost, installed capacity, reliability, estimated potential and social acceptance. Analytic Hierarchy Process (AHP) is employed as decision making tool. The study ranked wind energy as the top priority among the three renewable alternates, followed by biomass and solar energy w.r.t. Pakistan to supplement future energy demands. (author)
[en] The future trends of the industry require major renovations in the infrastructure of transmission, distribution, and storing of generated energy. With the increased use of renewable energy across the globe, energy storage (ES) systems have started to play a prominent role in shaping the future of the ES market. However, because of the uneven distribution of the renewable energy throughout the world, more emphasis must be made to the integration of power grids with the ES devices to utilize the excess power more effectively. In this paper, a study is performed regarding the integration of a hybrid system, consisting of a lithium-ion battery (LIB) and superconducting magnetic energy storage (SMES), into an interconnected microgrid operation. The structure of a microgrid is explained by analyzing the selected battery (LIB) and voltage source converter (VSC)-based SMES unit via MATLAB & Simulink. Finally, the voltage waveforms are compared and discussed in detail.