Results 1 - 10 of 2086
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[en] In this book for Master and engineering students as well as for engineers and researchers, the author aims at providing a comprehensive overview of the production of photovoltaic and thermodynamic solar electricity (fundamentals, state of the art, main envisaged innovations on the short and medium term). The first part addresses the solar resource: radiometric values, the Sun as an energy source, atmospheric attenuation, ground-based radiation measurement, the Sun's apparent movement, the Sun's position with respect to an inclined surface, energy collected by a surface on the ground. The second part addressed the photovoltaic conversion of solar energy: historical overview, the band diagram of semiconductors, doping of semiconductors and charge transport, light absorption in semiconductors, physics of photovoltaic cells, fabrication processes for cells and modules, photovoltaic modules, generators and systems, photovoltaic installations in isolated site, installations connected to the grid, integration of photovoltaic production to the electric power system. The third part addresses thermodynamic solar technologies based on concentration: historical perspective, the reasons for solar flux concentration, general principles and state of the art, plants with cylindrical-parabolic collectors, tower plants, thermal storage
[en] Climate change is one of the most challenging issues faced by humankind today. Scientific evidence regarding the existence of anthropogenic climate change was proven by the Intergovernmental Panel on Climate Change (IPCC). Based on the evidence, negotiations led to international agreements on the long-term stabilization of the climate system. In 2015, a limit on the global average temperature increase was set to 2°C, preferably 1.5°C, until 2100. To achieve this goal on a European scale, the EU agreed to reduce total greenhousegas (GHG) emissions by 80 to 95 % by 2050. Thereof, emission targets for individual sectors were derived. The effort is shared among member countries. Individual intermediate targets are being continually negotiated. However, a holistic plan that sets the pathway for implementing effective measures to achieve the GHG emission reduction targets in all sectors by 2050 is missing. It is expected that challenges to achieve the reduction will increase in the last twenty years due to the growing integration of variable renewable energy sources. In addition, anticipated demand shift from other sectors to the electricity sector and relatively strict reduction targets in the latter corroborate the priority to decarbonize the electricity sector. The cost-effective implementation of measures to achieve the GHG emission reduction targets requires a strategy based on optimal planning. Long-term economic depreciation of power plants and a radical technological change create a dynamic and a complex environment. Decisions taken on short-term scale affect the design of the electricity system on a long-term. Therefore, model-based studies help to unveil insights about the transition towards a decarbonized electricity supply and provide important information for planning of the future electricity system. Despite the large number of studies on the future of the electricity sector, cost-effective decarbonization pathways to achieve the GHG emission reduction goals are insufficiently explored. Successive transformation planning of the European electricity system is needed in order to achieve the GHG emission reduction targets by 2050. This thesis assesses cost-optimal decarbonization pathways for the European electricity sector to meet emission reduction targets by 2050. These pathways outline the transformation of the electricity supply infrastructure in successive 5-years increments until 2050. It includes investments in power plants, energy storage facilities, and the transmission system. For assessing these pathways, the multi-period, multi-region energy system model elesplan-m for European electricity sector was developed and used. This computer model is based on linear programming allowing the assessment of investment decisions constrained by technical and economic circumstances. These decisions are evaluated based on analyzing the electricity supply on an hourly scale for each reference year. The analyzed decarbonization pathways show that enormous effort is required to cut GHG emissions in the European electricity sector by 98 % by 2050 relative to 1990 levels. According to the investigated pathways, electricity generation by wind and photovoltaic (PV) power will meet the majority of the electricity demand by 2050. This requires 1,430 GW of wind power and 1,260 GW of PV power to be installed by 2050. Therefore, capacity of both technologies needs to be extended by approximately 40 GW on average per year. Enhanced international cooperation through the extension of cross-border transmission capacities allows a cost-effective implementation of climate protection measures in the electricity sector. The proposed electricity system design for 2050 includes 43 GW of pumped-hydro storage, 230 GW of battery energy storage systems, and 260 GW of power-to-gas (PtG) to balance supply and demand mismatches. Several sensitivity scenarios show that PtG is required to achieve climate change mitigation beyond the GHG reduction of 88 %. Carbon-intense electricity generation technologies, such as coal power, must be abandoned around 2035 to realize effective decarbonization. Cost of electricity supply is very likely to increase by approximately 60 % until 2050. The sensitivity scenarios show the cost increase only deviates by +/- 10 % relative to the reference case. If rising fuel prices, costs due to the impact of climate change, and other external costs would be incorporated in the cost of electricity supply, costs would be comparable to the expected cost increase of deploying renewables. Based on the results of this thesis, it can be concluded that a reliable political framework is required for a successful implementation of GHG reduction measures in the European electricity supply sector. A European-wide agenda to decarbonize the electricity sector allows cost-effective coordinated actions. A guaranteed reliable environment attracts investors to finance power plants, energy storage systems, and transmission system projects. Furthermore, it must be guaranteed that required technologies, i.e. power-to-gas, and manufacturing capacities for PV and wind power, are available. Immediate action is needed to realize climate change mitigation within the 2°C limits. Among other requirements, investments in coal power must be avoided and replaced by investments in renewable energy.
[en] The most important issue for the Republic of Armenia is to choose a new nuclear option, which will replace the existing unit after its decommissioning in 2026. The latest strategies for the development of the Armenian energy system are formulated in a Republic of Armenia governmental decree that was adopted in December 2015 and contained a long term (up to 2036) energy sector development strategy (referred to as ‘Strategy’ hereafter). This Strategy provides various possible expansion plans for the Armenian energy system, including different nuclear options. The future development of the Armenian energy system is expected to be mainly based upon nuclear energy and modern gas fired power generation plants, the development and expansion of economically viable and technically available renewable energy sources, and the diversification of fuel supply chains. At the same time, the Strategy document has not provided a final decision about the technologies expected to be implemented in the system. The main goal of the present study is to clarify and select the most attractive nuclear option for Armenia reflected in the Strategy by carrying out some additional evaluations and comparative analyses. For this purpose, the KIND approach and KIND-ET evaluation tool have been used. This report summarizes the main findings of the study.
[en] Since 2012, when Resolution No. 482 of ANEEL (National Agency for Electric Energy) created the Electric Energy Compensation System, it was possible for Brazilian consumers to generate their own electricity from renewable sources or qualified cogeneration, supply the surplus to the distribution network of your locality. This milestone motivated the industry to develop technology in the area of photovoltaic energy. In light of this new perspective, the objective of this article is to compare the generation of electric energy by Grid-Connected Photovoltaic Power System 3.1 kWp installed in the rural area of the State of Rondônia located in the Amazon region, where the climatic seasons are rain and dry, with the generation estimate of the PVSyst program. The results of this analysis suggest that the industry develop projects and research to improve the program when it involves grid-connected photovoltaic (PV) power system in the northern region. (author)
[en] Pairing of electrons either on the same lattice site or between neighboring sites has been studied. Recently discovered superconductivity in twisted bilayer graphene offers a new platform where superconductivity occurs in flat bands whose Wannier states envelop many graphene unit cells. Solved here is a spin-fluctuation mediated pairing eigenvalue problem with realistic Fermi surface. Owing to the unique arrangement of Wannier states in a triangular Moire lattice in this system, it obtains a nodal extended s-wave pairing symmetry. These results are compared with those of graphene on hBN with a different Moire lattice, and single-layer graphene with no Moire pattern
[en] Safeties of nuclear systems are to be verified during the design and licensing periods. The experiments are to be performed at severe conditions and require expensive facilities. The paper introduces an experimental methodology based on the analogy between heat and mass transfer. The basic idea is to replace heat transfer systems with corresponding mass transfer systems. Here the copper-sulfate electroplating system is used. This experimental method can achieve high buoyancy with small facilities due to the reduction of cupric ions at the cathode induces large density decrease of the fluid. A few published researches of the authors are summarized as the examples of the applications, simulating highly buoyant flow conditions of the In-Vessel Retention and External Reactor Vessel Cooling (IVR-ERVC), Reactor Cavity Cooling System (RCCS), and even a Critical Heat Flux (CHF) problems. Utilization of this analogy experimental method will ease the preliminary verification of the nuclear safety system. (author)
[en] The technically important design and safety criteria - both for regenerative as well as for conventional and nuclear energy systems - are still part of a sound basic training in energy technology. The 6th updated and revised edition imparts the relevant knowledge in a proven manner and enables the verification of the acquired knowledge by means of exercises. In addition, the book discusses criteria that must be taken into account for technology assessments (quantifiability of environmentally relevant decision criteria, socio-political and economic aspects) and encourages independent application of the findings. The clear presentation of the facts and the use of simple mathematical models allow readers from different disciplines to get an introduction to the subject.