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AbstractIron-acceptor (FeAc) pair association has been studied in compensated n-type silicon. A dynamic approach, based on the charge carrier recombination rates over the Fei trap level, leads to an explanation of the observed FeAc pairing reaction in compensated n-type silicon and extends the understanding of FeAc pairing kinetics. Association kinetics was used to measure a height dependent acceptor concentration profile. Even in compensated n-type silicon good agreement with expected concentrations is found.

AbstractAlthough the road-map of the oxy-fuel process seems to be very advanced, there are still plenty of open questions. One of the significant ones is the corrosive behaviour of the heat exchanger surfaces. The Institute of Combustion and Power Plant Technology, University of Stuttgart, performs research on the fireside corrosion under oxy-fuel and conventional combustion conditions for the current and supercritical power plants considering the influence of combustion modus, gas atmosphere and fly ash deposits on the waterwall and superheater surfaces. Since the oxy-fuel-combustion atmosphere is composed of recirculated flue gases and pure oxygen, significantly higher concentrations of CO2, SO2 and H2O are present compared to the conventional combustion of coal with air as an oxidizer. In the here presented study the influence of an oxy-fuel combustion of a hard-coal on the surface of selected superheater materials is discussed and compared to the results obtained for lignite. Especially the interactions between the flue gas atmosphere, ash deposits and heat exchanger materials are studied in detail. The investigation encompassed in this paper has been focused on impacts of oxide-scale growth, carbon enrichment of the materials and sulphur-induced corrosion.Increased sulphur-induced corrosion has been observed in samples exposed to the oxy-combustion atmosphere. The noticed higher depth of corrosive attack of the oxy-fuel samples might be explained by a higher partial pressure of SO2 which is characteristic for oxy-fuel process. Moreover in certain cases the sulphur might be released by the deposits. Beside that, the oxy-fuel samples were exposed to much higher partial pressures of carbon dioxide comparing to the air-case leading apparently to rapid and massive internal carbon enrichment in the oxide scale. Moreover dependence between the chromium content and oxidation ability of the austenitic materials surfaces was noticed under oxy-fuel conditions.

AbstractThe future European energy supply system will have a high share of renewable energy sources (RES) to meet the greenhouse gas emission policy of the European Commission. Such a system is characterized by the need for a strongly interconnected energy transport grid as well as a high demand of energy storage capacities to compensate the time fluctuating characteristic of most RE generation technologies. With the RE generators at the location of high harvest potential, the appropriate dimension of storage and transmission system between different regions, a cost efficient system can be achieved. To find the preferred target system, the optimization tool GENESYS (Genetic Optimization of a European Energy System) was developed. The example calculations under the assumption of 100% self-supply, show a need of about 2,500 GW RES in total, a storage capacity of about 240,000 GWh, corresponding to 6% of the annual energy demand, and a HVDC transmission grid of 375,000 GWkm. The combined cost for generation, storage and transmission excluding distribution, was estimated to be 6.87 ct/kWh.

The European Geosciences Union (EGU) brings together geoscientists from all over the world covering all disciplines of the Earth, planetary and space sciences. This geoscientific interdisciplinarity is needed to tackle the challenges of the future. One major challenge for humankind is to provide adequate and reliable supplies of affordable energy and other resources in efficient and environmentally sustainable ways. This Energy Procedia issue provides an overview of the contributions of the Division on Energy, Resources & the Environment (ERE) at the EGU General Assembly 2017.

Abstract This research is conducted to determine the limiting values of the geometric concentration when used with solar thermal system (thermoelectric generator) (TEG) to maintain desired hot and cold side temperatures for power generation. Experiments were conducted to determine the optimum solar concentration (aperture area/target area) using a thermoelectric generator sandwiched between the target plate and passive heat sink. A computer model is developed to solve the energy balance equations and find the optimum values for geometric concentration. It was observed that for the single configuration of heat sink and thermoelectric generator in a system, the trend of temperature difference between the hot and cold sides remain the same at different geometric concentrations. The optimum geometric concentration is determined for heat sinks in study. It is observed that with solar radiation intensity of 800 W/m2 and heat sink fin length of 0.15m the optimum geometric concentration is 13.

AbstractState of the art technologies like air-to-water heat pumps have become popular because of their high efficiencies and their supply by electricity rather than by gas or oil. As a direct result of this supply substitution and due to high load- shifting potential, electricity demand of heat pumps have to be taken into account into energy management strategies of the overall building. In this paper a new controller is discussed, which has predictive and adaptive properties and is able to optimize the running-times of non-modulating heat pumps.

Abstract Global primary energy consumption will continue to increase with a high rate to 2050, which will be a big challenge for countries to meet both global and regional energy demand. Pumped storage stations (PSS) integrated to a hybrid power system (HPS) with solar and wind power for China are under construction to tussle with this challenge. Historically, modeling of a PSS integrated HPS has been ignored the interaction effect between the shaft vibration and the governing strategies, which will increase the dynamic risk of PSS disconnected immediately to HPS. Here we unify the models of the hydro-turbine governing system and hydro-turbine generator units with a novel expression of hydraulic forces. We quantize all the parameter’s interaction contributions of PSS integration to HPS and validate this model with the existing models. Finally, we show the feasibility of PSS’s model in integrating of a HPS under steady and fault scenarios.

AbstractThis paper presents the experimental plans and designs as well as examples of predictive modeling of a pilot-scale CO2 injection experiment at the Heletz site (Israel). The overall objective of the experiment is to find optimal ways to characterize CO2 -relevant in-situ medium properties, including field-scale residual and dissolution trapping, to explore ways of characterizing heterogeneity through joint analysis of different types of data, and to detect leakage. The experiment will involve two wells, an injection well and a monitoring well. Prior to the actual CO2 injection, hydraulic, thermal and tracer tests will be carried out for standard site characterization. The actual CO2 injection experiments will include (i) a single well injection-withdrawal experiment, with the main objective to estimate in-situ residual trapping and (ii) a two-well injection-withdrawal test with injection of CO2 in a dipole mode (injection of CO2 in one well with simultaneous withdrawal of water in the monitoring well), with the objective to understand the CO2 transport in heterogeneous geology as well as the associated dissolution and residual trapping. Tracers will be introduced in both experiments to further aid in detecting the development of the phase composition during CO2 transport. Geophysical monitoring will also be implemented. By means of modeling, different experimental sequences and injection/withdrawal patterns have been analyzed, as have parameter uncertainties. The objectives have been to (i) evaluate key aspects of the experimental design, (ii) to identify key parameters affecting the fate of the CO2 and (iii) to evaluate the relationships between measurable quantities and parameters of interest.