Energy requirement for the production of silicon solar arrays

An assessment of potential changes and alternative technologies which could impact the photovoltaic manufacturing process is presented. Topics discussed include: a multiple wire saw, ribbon growth techniques, silicon casting, and a computer model for a large-scale solar power plant. Emphasis is placed on reducing the energy demands of the manufacturing process

Energy requirement for the production of silicon solar arrays

Photovoltaics is subject of an extensive technology assessment in terms of its net energy potential as an alternate energy source. Reduction of quartzite pebbles, refinement, crystal growth, cell processing and panel building are evaluated for energy expenditure compared to direct, indirect, and overhead energies

Arc behavior in low-voltage arc chambers

The arc behavior in an arrangement of parallel arc rails with a splitter plate in between has been investigated experimentally and in numerical computations. Thereby, the arc is simulated by coupling finite-volume modeling for the gasdynamics and finite-elements modeling for the electromagnetics. The formation of arc roots on the splitter plate can be described by a thin layer of elements with a current-density dependent specific resistance. The simulations were extended to model the experimental arrangement exactly. Additionally, net emission coefficients and radiation heat conductivity of air plasma instead of a simplified T4 net emission of a black body were used to model the radiative cooling of the arc. The results of the arc voltage, the arc movement and the splitting process have been compared to measurements and high speed movies of the arc and yield good correlation. Moreover, the simulations allow good insight into the temperature distribution of the arc and the movement of the pressure waves caused at the arc ignition.

Electromagnetic stray fields of the power supply systems of TEXTOR regarding the council recommendation (1999/519/EC)

The European Union adopted a Council Recommendation to limit the exposure of the general public to electromagnetic fields (EMF) (0 Hz-300 GHz), in July 1999. The new limits for EMF are much lower than in the past. As EMF from supplies and feeder lines of TEXTOR occur in places with public access the fields have to be known to be sure that protection limits are not exceeded or precautions can be taken against the exposure to the fields. Magnetic fields were measured in relevant areas. Different instruments have registered direct fields as well as alternating fields up to 30 kHz and from 27 MHz to 1 GHz. The mechanisms for the impacts of EMF and the sources of magnetic stray fields are listed. The results of the measurements are given and discussed. For areas where the limits are clearly exceeded, suggestions for measures or precautions to be taken are given. The results also show that in some areas further measurements have to be done. (C) 2003 Elsevier Science B.V. All rights reserved