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[en] This paper discusses developments in light collection which had their origin in efforts to construct high performance gas Cerenkov detectors for precision studies of hyperon beta decays at the ZGS. The resulting devices, know generally as open-quotes compound parabolic concentrators,close quotes have found applications ranging from nuclear and particle physics experiments to solar energy concentration, instrument illumination, and understanding the optics of visual receptors. Interest in these devices and the ideas underlying them stimulated the development of a substantial new subfield of physics: nonimaging optics. This progression provides an excellent example of some ways in which unanticipated - and often unanticipatable - applied science and open-quotes practicalclose quotes devices naturally emerge from first-rate basic science. The characteristics of this process suggest that the term open-quotes spinoffclose quotes commonly used to denote it is misleading and in need of replacement
[en] Solar energy has a huge global and European potential for sustainable generation of electricity, heat and fuels. Photovoltaic solar energy conversion (PV) and concentrating solar power (CSP) are the two options for electricity generation. In the longer term they may also be used to generate sustainable fuel, especially hydrogen, if that would turn out to be useful in the total energy mix. Because of the different nature of the PV and CSP conversion processes and the related distinctive features, they can be considered largely complementary Clearly, the combination of the two absolutely makes a winning team and may form (or even has to form) the basis of our future sustainable energy system. Grid parity is a rather simplified indicator of the competitiveness of PV. It is nevertheless very useful since it assumes the viewpoint of a potential investor in a PV system and has thus helped to define potential markets. Moreover the concept does roughly illustrate how long it takes PV to reach competitiveness in different segments of the electricity market. It may not be the Holy Grail but it is certainly no hype either. When used with care it is one key to the success of PV.
[en] Data resulting from the operation of the Solar Central Receiver Steam Production System at Weizmann Institute of Science was compared to data calculated from modelling computer codes on receiver tube surface temperatures, absorbed power, efficiency and steam quality. Good correspondence was shown between calculated and observed data. Extrapolation to higher flux inputs and lower circulation rates using the models indicated that the heat flux on the evaporation panel could safely be raise to 900 kw/m2 and to saturate steam temperatures of 260 degrees C from the original designed 300 kw/m2 and 200 degrees C respectively. Furthermore a preliminary economic analysis indicated that this cavity receiver system could be operated competitively at levels 10-100 megawatts thermal equivalent steam production. (authors)
[en] The present master thesis conducts technical and economic simulations of large-scale Photovoltaic (PV) and Concentrated Solar Power (CSP) plants for the Moroccan Solar Plan. It provides a database of performance indicators such as energy yields, capacity factors, typical efficiencies and losses of technical components, LCOE, and difference costs (DC: LCOE minus avoided costs of the conventional power system) for fixed tilted, 1-axis horizontal, 1-axis vertical and 2-axis tracking PV and CSP with no, 6, 12 and 18 full load hours of thermal storage. HelioClim irradiation data of 2005 for the sites in Ouarzazate, Ain Ben Mathar, Boujdour, Laayoune and Tarfaya is used ranging between 1,927 - 2,428 kWh/m"2/y (DNI) and 1,968 - 2,154 kWh/m"2/y (GHI). In the base scenario minimum LCOE are 9.6 - 5.4 EURct/kWh for PV (2012 - 2020) varying between 0.90 - 1.55 EURct/kWh among sites and technologies. CSP reaches 12.8 - 9.2 EURct/kWh and a bandwidth of 2.3 - 1.6 EURct/kWh. Average DC are lowest for horizontal 1-axis tracking (0.4 and -7.7 EURct/kWh for plants built in 2012 and 2020 respectively) and CSP with 6 hours of storage (1.3 and -3.5 EURct/kWh). PV is cheaper for all sites and technologies due to higher learning curves and less initial investment, but cannot contribute to coverage of the daily evening peak in Morocco. Four different MSP-scenarios with 2000 MW of solar energy require total investments of 3.7 - 7.5 billion EUR and yield 7.9% - 12.8% of the electricity demand in 2020 (given a growth 7%/y) depending on the ratio of PV and CSP utilization. The average LCOE are 8.3 - 11.7 EURct/kWh and the total discounted DC (10%/y) are -254 - 391 million EUR. Thus, solar energy is partly less expensive than a business-as-usual scenario. An extensive sensitivity analysis for WACC and price escalation of conventional energy shows that for only PV and only CSP scenarios in 55 and 22 out of 72 cases the DC are negative - although no environmental costs for conventional generation are internalized. The weighted average extra costs of a feed-in tariff for the analyzed scenarios range between 0.4% - 8.1% of today's electricity price until break-even with conventional energy.
[en] Solar energy has received much interest in recent years, being a clean (free of pollution or other environmental damage) and inexhaustible energy source. It is also considered safer than some other non conventional energy sources (like nuclear energy). The interest in solar energy is motivated mainly by the growing awareness of the environmental problems associated with the use of conventional fuels. However, solar energy may become a serious alternative only if it can be used efficiently in major energy consuming industries (like the chemical industry), or be used for electricity generation. Those facilities are nowadays solely dependent on fossil fuels as the prime source of energy. The solar energy, reaching the earth in the form of radiation, can be utilized either by direct quantum conversion using photo-voltaic solar cells, or by converting the radiation into thermal energy, to be used directly for heating, or to feed a thermal to electric converting cycle. After three decades of huge spending on the development of photo-voltaic systems those devices are commercially competitive only on a very small energy scale, while solar thermal commercial applications are more attractive. Prominent examples are the domestic heating water receivers (direct thermal), and LUZ International electricity generation plants which are currently operated on a commercial basis, supplying 80 MWe per plant. Direct thermal exploitation of solar energy is naturally more efficient than converting to electricity, but is limited to specific applications and locations especially since thermal storage at high temperature is not commercially viable. Efficient electricity production at a competitive price is clearly the biggest opportunity for solar energy . (author)
[en] A four stage asymmetric type depressed collector has been designed for the Israeli mm-wave FEM that is driven by a 1.4 MeV, 1.5 A electron beam. After leaving the interaction section the spent beam has an energy spread of 120 keV and 75 π mm mrad normalized beam emittance. Simulations of the beam transport system from the undulator exit through the decelerator tube into the collector have been carried out using EGUN and GPT codes. The latter has also been employed to study trajectories of the primary and scattered particles within the collector, optimizing the asymmetrical collector geometry and the electrode potentials at the presence of a deflecting magnetic field. The estimated overall system and collector efficiencies reach 50% and 70%, respectively, with a beam recovery of 99.6%. The design is aimed to attain millisecond long pulse operation and subsequently 1 kW average power. Simulation results are implemented in a mechanical design that leads to a simple, cost efficient assembly eliminating ceramic insulator rings between collector stages and the associated brazing in the manufacturing process. Instead, each copper plate is supported by insulating posts and freely displaceable within the vacuum chamber. We report on the simulation results of the beam transport and recovery systems and on the mechanical aspects of the multistage collector design
[en] A solar energy powered falling film evaporator with film promoter was developed for concentrating diluted solutions (industrial effluents). The procedure proposed here does not emit CO2, making it a viable alternative to the method of concentrating solutions that uses vapor as a heat source and releases CO2 from burning fuel oil in a furnace, in direct opposition to the carbon reduction agreement established by the Kyoto protocol. This novel device consists of the following components: a flat plate solar collector with adjustable inclination, a film promoter (adhering to the collector), a liquid distributor, a concentrate collector, and accessories. The evaporation rate of the device was found to be affected both by the inclination of the collector and by the feed flow. The meteorological variables cannot be controlled, but were monitored constantly to ascertain the behavior of the equipment in response to the variations occurring throughout the day. Higher efficiencies were attained when the inclination of the collector was adjusted monthly, showing up to 36.4% higher values than when the collector remained in a fixed position