Das Projekt "Cover sealing of a blast furnace dust dump - a comparative evaluation of in situ test fields" wird vom Umweltbundesamt gefördert und von Universität Trier, Fachbereich VI, Lehrstuhl für Geologie durchgeführt. Objective: The purpose of this EC research project is to obtain data on the water balance and water movement in a cover sealing system and to quantify the functioning of different sealing systems under natural conditions. A comparative assessment is to be made of the effectiveness and cost-effectiveness of different in situ test fields. General Information: The requirements of a cover seal are fundamentally different from those of a base liner, as they are exposed to different risks and they are used for different purposes. There are few results available on the long-term effectiveness of different capping systems. The function and effectiveness of such systems have been studied in laboratory experiments, but their results cannot simply be extrapolated to natural conditions. The cover seal of landfills or contaminated sites has the following functions: 1. to minimize seepage of rainwater into the dump; 2. to prevent leaching of soluble contaminants into surface waters (particularly at the edges); 3. to serve as a substrate for recultivation. These functions must be maintained in the long term, i.e. the cover seal must be protected from erosion, frost, drying out, clogging, settling, penetration by roots and burrowing, etc. Normally, a combination of covering layers, drainage systems and barrier layers is used to meet these requirements. Planting of the cover layers helps to protect the deeper layers from direct atmospheric and biotic attack. The cover layer and the vegetation should store a large proportion of the precipitation and/or increase its evaporation. The drainage layer below is designed to channel the water seeping in from the cover layer to the edge. The barrier layer below this can be built up of various materials: a) plastic sheeting; b) cohesive, mineral soil (mineral seal); c) non-cohesive, mineral soil (capillary barrier); d) asphalt concrete. The Technical Instruction on Municipal Waste (regulations in force in Germany) requires a landfill site to be capped once it is full. In the case of category I landfills, a simple mineral seal is sufficient as a covering. After settling has ceased, there must be a gradient greater than or equal to 5 per cent. A drainage layer greater than or equal to 30 cm must be applied on top of the mineral seal. A 1 m thick recultivation layer must be applied on top of the drainage layer, which must consist of cultivable soil and be planted with suitable vegetation. The recultivation layer must be capable of protecting the mineral layer from root penetration and frost damage. The vegetation must provide sufficient protection against wind or water erosion. The water balance of the landfill capping system must be in equilibrium. The state of the recultivation layer and the vegetation of the closed landfill must be monitored at six-monthly intervals to detect any erosion damage, settling or deformation.
Das Projekt "Substrat- und Sperrschichtoptimierung fuer im CVD-Verfahren hergestellte Duennschicht-Siliziumkristall-Solarzellen" wird vom Umweltbundesamt gefördert und von Fraunhofer-Institut für Solare Energiesysteme durchgeführt. Objective: A consortium has been formed by partners stemming from research and industry in order to make a further step towards the development of a cost-effective thin-film crystalline Si solar cell technology, based on thermally assisted Chemical Vapour Deposition (CVD) as deposition technique. This project should result in a thin-film crystalline Si low-cost PV module with a competitive cost/Wp. Description of work: The numerous possible options for thin-film crystalline Si solar cells (for substrate and barrier layer) and the absence of real progress on the level of equipment development for large-volume Si-layer deposition bear an inherent risk for subcritical research in this area. The consortium defined a clear strategy as far as substrates and deposition system are concerned. - Concerning the substrates, the number of options has been reduced to 3 options (Si-ribbons, a conductive ceramic: Si-infiltrated SiAlON and an insulating ceramic: SiAlON). - Together with the development and optimisation of the barrier layers, 4 technically relevant substrate/barrier layers schemes are investigated on cell level: Si-ribbons with and without barrier layer, Si-infiltrated SiAlON-substrates with a conductive SiC-layer, SiAlON-substrates and Si-ribbons with an insulating oxide barrier layer. After the Midterm Assessment, the number of substrate/barrier schemes is reduced to 2 (a conductive and non-conductive scheme), based on the results of a laboratory-type comparison of cells and the first cost projections. - Concerning the development of a high-throughput CVD-system, first steps toward a continuous Si-deposition system are taken. The consortium wishes to assess and reduce the running costs of such system. Specifically the costs associated with waste treatment and a reduction of the gas consumption through a H2-recirculation system will be looked at in more detail . In the first phase of the project these aspects will be studied. After the Midterm Assessment this deposition system will be intensively used for the growth of the Si-layers on the selected substrates, which will be processed into solar cells using processes, compatible with the industrial reality. Expected Results and Exploitation Plans: - The selection of a suitable low-cost substrate, compatible with Si-deposition by means of thermally-assisted Chemical Vapour Deposition (and possibly a liquid phase recrystallisation step); - The development of suitable barrier layers to prevent impurity indiffusion from the low-cost substrate into the active layer and to optimise internal reflection; - The assessment of a continuous high-throughput CVD-reactor, compatible with the requirements of the solar cell industry; - A module of 30x30 cm2 on the selected conductive substrate/barrier layer combination with an efficiency = 12 per cent obtained by a two-side contacting technology. Prime Contractor: Interuniversity microelectronics centre, microsyst4ems, components and packaging advanced solar cells