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The integration of high temperature thermal energy storages into existing conventional power plants can help to reduce the CO2 emissions of those plants and lead to lower capital expenditures for building energy storage systems, due to the use of synergy effects [1]. One possibility to implement that, is a molten salt storage system with a powerful power-to-heat unit. This paper presents two possible control concepts for the startup of the charging system of such a facility. The procedures are implemented in a detailed dynamic process model. The performance and safety regarding the film temperatures at heat transmitting surfaces are investigated in the process simulations. To improve the accuracy in predicting the film temperatures, CFD simulations of the electrical heater are carried out and the results are merged with the dynamic model. The results show that both investigated control concepts are safe regarding the temperature limits. The gradient controlled startup performed better than the temperature-controlled startup. Nevertheless, there are several uncertainties that need to be investigated further. [ABSTRACT FROM AUTHOR]

Central receiver systems with open volumetric air receiver and packed bed thermal storage are an alternative to the currently deployed salt and steam receiver plants. The air receiver technology is being tested as a complete system at the 1 MWe test and demonstration plant Solar Tower Jülich since 2009 and shows high robustness and availability. Recent developments focused on increasing the thermal receiver efficiency. Changing the receiver geometry to a cavity type and further structural improvements resulted in an efficiency increase to above 85%, as experiments and CFD simulation models show. The high dynamic flexibility could be further enhanced. A commercial reference plant with 50 MWe power level was defined for a potential location in South Africa. An LCOE analysis based on an annual performance simulation was conducted for several design and operational alternatives. Under good conditions, results show LCOE values below 90 €/MWh for the single 50 MWe standard unit. Higher power levels can be reached by multiplying such standard units, leading to further cost savings. [ABSTRACT FROM AUTHOR]

The yield of solar thermal power plants is strongly affected by disturbances in the irradiation condition through passing clouds. This effect is even more prominent when the clouds shade the solar field only partially as the irradiance situation cannot be fully measured by few measurement points in the field. In this paper, the benefit of using nowcasting systems to produce highly resolved irradiance maps on the field during start-up is studied. A simulation tool is used to dynamically model all the loops and piping in a reference commercial solar field. Automatic solar field controllers allow the model to operate during different situations. The performance of the field under a reference state-of-the-art controller is compared against a controller using the irradiance maps from nowcasting systems. The benefit during start-up processes is found to be significantly lower than the benefit the system makes during normal solar field operation. However, there is more potential shown for more advanced controllers, like model-predictive control. [ABSTRACT FROM AUTHOR]