• Energy Research
• 7. Clean energy close
• DE close
• Energy Procedia close

Abstract The paper presents an equivalent circuit based simulation model for the static and dynamic behavior of lithium-ion battery systems and explains the different steps of the theoretical and experimental modeling process. The equivalent circuit based model describes the voltage-current characteristic, the state of charge behavior and the occurring losses of the battery system. A parameter identification method based on three characteristic experiments, a cycle test, an open circuit voltage test and pulse tests, is introduced. The model parameters are estimated employing a nonlinear optimization method. Furthermore, the experimental test bed for investigation of lithium-ion battery systems is described. The battery model approach is demonstrated and validated for a commercial 5 kWh lithium-ion battery system, including the model validation for test profiles and emulated battery charging and discharging profiles of a real photovoltaic home storage application. The comparison of measured and simulated voltage profiles indicates an excellent performance of the battery model.

AbstractPyrochemical methods for reprocessing of spent nuclear fuel are under development as an alternative to the hydrometallurgical processes. The pyrochemical reprocessing process developed in ITU is based on electrorefining of spent fuel in molten LiCl-KCl salt using solid aluminium cathodes. This is followed by a chlorination process for the recovery of actinides from the actinide-aluminium alloys formed and exhaustive electrolysis is proposed for clean-up of the salt from the remaining actinides. In this paper, all investigated techniques are described and the main achievements are summarised. The emphasis is given to the electrorefining, which represents the core process for homogeneous recovery of all actinides from the spent fuel. High efficiency of the process and excellent recovery of actinides over lanthanides have been achieved and very high capacity of solid aluminium to take up actinides has been demonstrated.

Abstract Commonly, wake models are calibrated in wind tunnels or using flow simulations with a wide degree of physical details. In general, it is assumed that these methods cannot fully reproduce the real operating conditions of wind turbines. This research aims at investigating the calibration of an analytical single wake model in relation to full-scale measurements. Within this scope, we fitted the wake model to wake measurements realised with a lidar installed on the nacelle of an offshore wind turbine. We studied the parameters returned by the fit separating cases at different levels of atmospheric turbulence and thrust on the wind turbine rotor. Comparing the results with a published calibration based on few LES wind fields representative for partial load conditions, we achieved good agreement when the considered wind turbines operated in similar conditions. For other situations, i.e. at full load, we found different calibrations of the model parameters. Our results show that and how nacelle-based lidar measurements can be complementary in the development of wake models.

AbstractOne of the advantages of solar thermal power plants (STPPs) with molten salt as heat transfer fluid is the direct storage system. This means that the thermal energy collected by the solar field and the electric power generation can be fully decoupled. The plant operator must therefore make the daily decision when to start-up or to shut-down the power block (PB). Normally, the solar field of these STPPs is overdesigned which leads to dumping of solar energy during days with high solar radiation, due to the inability of the hot tank and the PB to consume all the collected thermal energy. The PB must therefore start as soon as possible to prevent excessive dumping of solar energy. Contrarily, on days with low solar radiation, the PB should not start too early to prevent a second start-up on this day, because of a low hot tank level. In order to operate within these counter bounds, a fixed and a dynamic operation strategy are proposed. The so-called solar-driven strategy serves as a reference. Using this strategy, the PB operates whenever the solar field is online. The two proposed operation strategies are compared to the reference strategy by means of a transient STPP simulation model. Using the dynamic operation strategy, the annual unnecessary PB start-ups and the auxiliary heater thermal energy for anti-freeze protection are decreased, whereas the annual net electricity is increased.

AbstractEvaporation cooling systems are currently deployed in the majority of operating Concentrating Solar Power (CSP) plants. However, the fundamental drawback of this approach is that large quantities of water are used in the cooling tower, so that this solution will be not applicable for a large-scale CSP development in arid regions. In fact, in most of the sites suitable for CSP applications, ambient temperatures are typically high and water is scarcely available, or the cost of transporting water to these sites is prohibitive. For this reason, at these sites dry cooling will be the only viable option. This paper analyses the impact of dry cooling systems on technical and economic plant performances, considering several condenser layouts, different operation strategies and economic boundary conditions. In particular, the capacity and the operation of the thermal energy storage can be optimized in order to maximize power production, e.g. by preferential plant commitment at night hours. The analysis is carried out for three selected locations with real meteorological data by means of annual simulations with hourly time steps.

AbstractWe present the latest results of our back contact back silicon heterojunction (BCB-SHJ) solar cells with punctiform absorber contacts. We discuss the technological challenges and present a basic cell structure reaching an e_ciency of (17.1 _ 0.5)% on our BCB-SHJ solar cells. The main loss mechanisms a_ecting the fill factor and the VOC are identified and are found to be avoided by minor process modifications.

AbstractThis article summarizes scientific knowledge and practical experiences on the release and capture of SO2 and SO3 with a special focus on the implications of oxy-fuel combustion conditions on sulphur emission behaviour. Results, obtained at the experimental, 500 kWth atmospheric, pulverized fuel combustion rig (KSVA) of the IFK regarding sulphur oxide (SO2/SO3) emissions and capture behaviour are presented. The experimental plant was operated with pre-dried sulphur rich lignite in air and oxy-fuel combustion mode. The following issues are highlighted in particular:•General and transient behaviour of SO2 emissions under air and oxy-fuel combustion conditions SO3•separation behavior of the ESP under oxy-fuel conditions•Differences of ESP ash qualities from air and oxy-fuel operation