Feldhoff J.F.,German Aerospace Center |
Schmitz K.,Flagsol GmbH |
Eck M.,German Aerospace Center |
Schnatbaum-Laumann L.,Solar Millennium AG |
And 3 more authors.
Solar Energy | Year: 2012
Parabolic trough power plants are currently the most commercially applied systems for CSP power generation. To improve their cost-effectiveness, one focus of industry and research is the development of processes with other heat transfer fluids than the currently used synthetic oil. One option is the utilization of water/steam in the solar field, the so-called direct steam generation (DSG). Several previous studies promoted the economic potential of DSG technology (Eck et al., 2008b; Price et al., 2002; Zarza, 2002). Analyses' results showed that live steam parameters of up to 500. °C and 120. bars are most promising and could lead to a reduction of the levelized electricity cost (LEC) of about 11% (Feldhoff et al., 2010). However, all of these studies only considered plants without thermal energy storage (TES). Therefore, a system analysis including integrated TES was performed by Flagsol GmbH and DLR together with Solar Millennium AG, Schott CSP GmbH and Senior Berghöfer GmbH, all Germany. Two types of plants are analyzed and compared in detail: a power plant with synthetic oil and a DSG power plant. The design of the synthetic oil plant is very similar to the Spanish Andasol plants (Solar Millennium, 2009) and includes a molten salt two-tank storage system. The DSG plant has main steam parameters of 500. °C and 112. bars and uses phase change material (PCM) for the latent and molten salt for the sensible part of the TES system. To enable comparability, both plants share the same gross electric turbine capacity of 100. MWel, the same TES capacity of 9. h of full load equivalent and the same solar multiple of the collector field of about two. This paper describes and compares both plants' design, performance and investment. Based on these results, the LEC are calculated and the DSG plant's potential is evaluated. One key finding is that with currently proposed DSG storage costs, the LEC of a DSG plant could be higher than those of a synthetic oil plant. When considering a plant without TES on the other hand, the DSG system could reduce the LEC. This underlines the large influence of TES and the still needed effort in the development of a commercial storage system for DSG. © 2011 Elsevier Ltd.
Torres E.,Max Planck Institute Für Eisenforschung |
Torres E.,Technological University of Bolívar |
Blumenau A.T.,Max Planck Institute Für Eisenforschung |
Blumenau A.T.,Schott Solar AG |
Biedermann P.U.,Max Planck Institute Für Eisenforschung
ChemPhysChem | Year: 2011
The translational and orientational potential energy surfaces (PESs) of n-alkanethiols with up to four carbon atoms are studied for (√(3) × √(3))R30° self-assembled monolayers (SAMs). The PESs indicate that methanethiol may form SAM structures that are not accessible for long-chain thiols. The tilt of the thiol molecules is determined by a compromise between the preferred binding geometry at the sulfur atom and the steric requirements of the alkane chains. The Au-S bond lengths, offset from the bridge position (brg), and the Au-S-C bond angles result in tilt angles of the S-C bond in the range of 55-60°. As DFT/generalized gradient approximation systematically underestimates chain-chain interactions, the binding energies are corrected by comparison to MP2 interaction energies of alkane dimers in SAM-like configurations. The resulting thiol binding energies increase by approximately 1 kcal mol -1 per CH 2 group, which results in a substantial stabilization of long-chain SAMs due to chain-chain interactions. Furthermore, as the chain length increases, the accessible range of backbone tilt angles is constrained due to steric effects. The combination of these two effects may explain why SAM structures with long-chain thiols exhibit higher order in experiments. For each thiol two favorable SAM structures are found with the sulfur head group at the fcc-brg and hcp-brg positions, respectively. These domains may coexist in thermal equilibrium. In combination with the symmetry of the gold (111) surface, this raises the possibility of up to six different domains on single-crystal terraces. Reconstructions by an adatom or vacancy of ethanethiol SAMs with (√(3) × √(3))R30° lattice are also studied using PES scans. The results indicate that adsorption of thiols next to a vacancy is favorable and may lead to point defects inside SAMs. Showing potential: The translational and orientational potential energy surfaces of n-alkanethiols with up to four carbon atoms are studied for (√(3) × √(3))R30° self-assembled monolayers (SAMs, see picture). The binding energies with the van der Waals interactions corrected using MP2 calculations increase by about 1 kcal mol -1 per CH 2 group. This trend and the increasingly confined accessible range of the tilt angles may contribute to the higher order observed in long-chain thiol SAMs on gold. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Agency: European Commission | Branch: FP7 | Program: CP-CSA | Phase: ENERGY.2013.10.1.10 | Award Amount: 21.20M | Year: 2014
Concentrating Solar Thermal Energy encompasses Solar Thermal Electricity (STE), Solar Fuels, Solar Process Heat and Solar Desalination that are called to play a major role in attaining energy sustainability in our modern societies due to their unique features: 1) Solar energy offers the highest renewable energy potential to our planet; 2) STE can provide dispatchable power in a technically and economically viable way, by means of thermal energy storage and/or hybridization, e.g. with biomass. However, significant research efforts are needed to achieve this goal. This Integrated Research Programme (IRP) engages all major European research institutes, with relevant and recognized activities on STE and related technologies, in an integrated research structure to successfully accomplish the following general objectives: a) Convert the consortium into a reference institution for concentrating solar energy research in Europe, creating a new entity with effective governance structure; b) Enhance the cooperation between EU research institutions participating in the IRP to create EU added value; c) Synchronize the different national research programs to avoid duplication and to achieve better and faster results; d) Accelerate the transfer of knowledge to industry in order to maintain and strengthen the existing European industrial leadership in STE; e) Expand joint activities among research centres by offering researchers and industry a comprehensive portfolio of research capabilities, bringing added value to innovation and industry-driven technology; f) Establish the European reference association for promoting and coordinating international cooperation in concentrating solar energy research. To that end, this IRP promotes Coordination and Support Actions (CSA) and, in parallel, performs Coordinated Projects (CP) covering the full spectrum of current concentrating solar energy research topics, selected to provide the highest EU added value and filling the gaps among national programs.
Pohl J.,TU Darmstadt |
Muller M.,Schott Solar AG |
Seidl A.,Schott Solar AG |
Albe K.,TU Darmstadt
Journal of Crystal Growth | Year: 2010
Twin formation in silicon growth from the melt is examined by molecular dynamics (MD) simulations. For a moderate undercooling of 25 K, we find that twins do not nucleate on (1 1 1) microfacets in the perfect crystal, but exclusively occur in the vicinity of grain boundaries. Only at an undercooling of 150 K, we observe the formation of metastable twin bounded loops with incoherent interfaces to the matrix consisting of coherency and anticoherency dislocations. In conclusion, the nucleation of stable twins in silicon growth requires the presence of a grain boundary or more general of a three-phase boundary, but is unlikely to occur on ideal (1 1 1) facets because of the excess energy of the interfacial area between matrix and twinned crystal. © 2009 Elsevier B.V. All rights reserved.
Kiessling F.-M.,Leibniz Institute for Crystal Growth |
Bullesfeld F.,Schott AG |
Dropka N.,Leibniz Institute for Crystal Growth |
Frank-Rotsch C.,Leibniz Institute for Crystal Growth |
And 2 more authors.
Journal of Crystal Growth | Year: 2012
Solar-grade boron doped silicon has been directionally solidified in a vertical gradient freeze-type furnace equipped with KRISTMAG ®- heaters to study the influence of travelling magnetic fields (TMFs) on the ingot quality. As-grown silicon ingots of 22×22×13 cm 3 in volume were cut vertically and analysed. Information was obtained on the curvature of the melt-solid interface, the grain size distribution, the content of SiC and Si 3N 4 particles and the electrical activity of defects. TMFs were used to enhance melt stirring and to control the growth interface shape. Primarily inclusion-free ingots were solidified with grains of several centimetres in size. Minority carrier lifetimes of τ=20-30 μs were measured on polished surfaces of cuts from as-grown ingots. The concentrations of carbon, oxygen and nitrogen were determined by FTIR spectroscopy to (3-4)×10 17 atoms/cm 3, (2-3)×10 17 atoms/cm 3 and (0.6-2)×10 15 atoms/cm 3, respectively. Mean etch pit densities were evaluated on vertical cuts as low as (2-3)×10 3 cm -2. © 2012 Elsevier B.V.
Schott AG and Schott Solar AG | Date: 2011-04-26
Photovoltaic installations and their parts and fittings, namely, solar cells, solar modules, converters, batteries, accumulators and connecting devices for electrical circuits. Solar collectors, solar receivers. Unworked or semi-worked glass except glass for building. Scientific and technological consulting services in the fields of solar energy and photovoltaic; technical analysis and research services in the fields of solar energy and photovoltaic; design and technical planning of energy production plants, especially solar current production plants.
Herlufsen S.,Institute for Solar Energy Research Hamelin |
Bothe K.,Institute for Solar Energy Research Hamelin |
Schmidt J.,Institute for Solar Energy Research Hamelin |
Schmidt J.,Leibniz University of Hanover |
And 3 more authors.
Solar Energy Materials and Solar Cells | Year: 2012
We apply the approach of dynamic photoluminescence lifetime imaging to a multicrystalline silicon brick. The dynamic approach allows the calibration-free determination of the bulk carrier lifetime of silicon bricks prior to wafer sawing. Using an indium gallium arsenide camera, we determine the bulk lifetime from the time-dependent luminescence emission for a modulated optical excitation. A ratio, including four photoluminescence images, acquired at different times during the modulated excitation, is calculated and found to depend on the camera integration time and the bulk lifetime. We demonstrate that the exact value of the surface recombination and the thickness of the brick are not required for the determination of the bulk carrier lifetime with the dynamic photoluminescence technique. The bulk lifetime is obtained locally by comparing the experimentally determined ratio with the simulated ratio for each image pixel. Since we are investigating the ratio of photoluminescence images containing information of the time dependence of the excess carriers, the doping-dependent luminescence emission has not to be corrected for the typical height-dependent doping variations. Therefore, the dynamic photoluminescence lifetime imaging technique is well suited for the investigation of bricks. © 2012 Elsevier B.V. All rights reserved.
ARCHETYPE SW550 - Demonstration of innovating parabolic solar trough using an alternative heat transfer fluid producing electricity and fresh water: ARChimede Hot Energy TYPology Enhanced Water Solar 550
Agency: European Commission | Branch: FP7 | Program: CP | Phase: ENERGY.2010.2.9-1 | Award Amount: 54.12M | Year: 2012
ARCHETYPE SW550 will design, build and operate the Worlds first industrial size Concentrated Power & Fresh Water Plant based on parabolic trough technology. It will efficiently integrate in a single plant the direct molten salt solar field, a twin tank storage system with a dedicated power block, a fresh water production unit and hybridization biomass system plant. It aims at demonstrating the performances of the Worlds first direct molten salt CSP stand alone plant where the inlet turbine temperature is 530C and molten salts are used directly into the solar trough collectors fully integrating the production of electricity, fresh water and integration with niomass. ARCHETYPE SW550 will also design and develop the innovative key components which will allow to improve the overall efficiency of the plant and to reduce the costs. Performances, costs of operation and life-cycle of components of the integrated fresh water system will be monitored and analyzed to demonstrate the improvements on the thermodynamic cycle. All participants are strongly interested in developing ARCHETYPE SW550 for which relevant commitments and permits are already in place. EGP has a strong experience in design and implementation of industrial power plant expecially in renewable, through respectively expertise of company ENEL Innovation and Engineering. LEC expected from ARCHETYPE SW550 should be 0.21 /kWh; during the operation the values of energy production and the cost of operation will be constantly monitored to verify the LEC. Fresh water production costs will benefit from the integration with the solar fed thermal cycle, thus achieving a monitored advantage in comparison with currently available technologies. Finally, ARCHETYPE SW550 will spread demonstration results all around the Mediterranean areas, potentially connectible to EUs grid and where power and fresh water are needed, in order to foster diffusion of CSP coupled with fresh water production and to allow a faster spreading of this technology.
Schott Solar AG | Date: 2010-05-17
Process for producing strip-shaped and/or point-shaped electrically conducting contacts on a semiconductor component like a solar cell, includes the steps of applying a moist material forming the contacts in a desired striplike and/or point-like arrangement on at least one exterior surface of the semiconductor component; drying the moist material by heating the semiconductor component to a temperature T_(1 )and keeping the semiconductor element at temperature T_(1 )over a time t_(1); sintering the dried material by heating the semiconductor component to a temperature T_(2 )and keeping the semiconductor component at temperature T_(2 )over a time t_(2); cooling the semiconductor component to a temperature T_(3 )that is equal or roughly equal to room temperature, and keeping the semiconductor component at temperature T_(3 )over a time T_(3); cooling the semiconductor component to a temperature T_(4 )with T_(4)35 C. and keeping the semiconductor component at temperature T_(4 )over a time T_(4); and heating the semiconductor component to room temperature.
Schott Solar AG | Date: 2011-09-09
For forming the separating lines, (5, 6, 7) which are produced in the functional layers (2, 3, 4) deposited on a transparent substrate (1) during manufacture of a photovoltaic module with series-connected cells (C1, C2, . . . ), there are used laser scanners (8) whose laser beam (14) produces in the field (17) scanned thereby a plurality of adjacent separating line sections (18) in the functional layer (2, 3, 4). The laser scanners (8) are then moved relative to the coated substrate (1) in the direction (Y) of the separating lines (5, 6, 7) by a distance corresponding at the most to the length (L) of the scanned field (17) to thereby form continuous separating lines (5, 6, 7) through mutually flush separating line sections (18).