Evaluation of annual efficiencies of high temperature central receiver concentrated solar power plants with thermal energy storage.

Abstract

The current study has examined four cases of a central receiver concentrated solar power plant with thermal energy storage using the DELSOL and SOLERGY computer codes. The current state-of-the-art base case was compared with a theoretical high temperature case which was based on the scaling of some input parameters and the estimation of other parameters based on performance targets from the Department of Energy SunShot Initiative. This comparison was done for both current and high temperature cases in two configurations: a surround field with an external cylindrical receiver and a north field with a single cavity receiver. There is a fairly dramatic difference between the design point and annual average performance, especially in the solar field and receiver subsystems, and also in energy losses due to the thermal energy storage being full to capacity. Additionally, there are relatively small differences (<2%) in annual average efficiencies between the Base and High Temperature cases, despite an increase in thermal to electric conversion efficiency of over 8%. This is due the increased thermal losses at higher temperature and operational losses due to subsystem start-up and shut-down. Thermal energy storage can mitigate some of these losses by utilizing larger thermal energy storage to ensure that the electric power production system does not need to stop and re-start as often, but solar energy is inherently transient. Economic and cost considerations were not considered here, but will have a significant impact on solar thermal electric power production strategy and sizing.

A review and perspective of efficient hydrogen generation via solar thermal water splitting

“…Reaction rates and reactor residence times (with associated heat losses for any hold times or storage within the process) may dramatically impact efficiency values and could greatly affect reactor design. Transient operation is important in solar processes, and more detailed models would be useful for predicting the effects of different materials and process designs to daily start‐up and shut‐down processes, and less‐than‐optimal solar irradiance, both of which can significantly impact performance . More detailed models incorporating these effects will make better economic assessment of processes possible.…”

Storage capacities required for a solar thermal plant to avoid unscheduled reductions in output

“…This is because as the storage capacity required to achieve continuous energy output during the rare occurrences of long periods of low insolation is extremely large and is inevitably associated with substantial dumping of excess energy. This combination of a low utilisation factor, together with literature reviews citing an overall system efficiency for economic viability in the range of 13-16% for concentrated solar power plants with TES (Bradshaw et al, 2002;Kolb, 2011;Ehrhart and Gill, 2013), suggests that such a system that aims to achieve continuous power supply through increasing energy storage size is unlikely to be economically viable in the foreseeable future.…”

“…Recent developments in TES technologies have resulted in them achieving relatively high daily thermal storage efficiencies, of around 98-99% for molten-salt storage systems in commercial solar power towers operating at approximately 565°C (Bradshaw et al, 2002;Kolb, 2011;Ehrhart and Gill, 2013). However, it is to be noted that at significantly higher operating temperatures (e.g.…”

Dynamic Modeling of a Central Receiver CSP System in Modelica

“…As no efficiency matrix has been published for the Solar Two heliostat field, a matrix calculated for a similar type of field was modified and used. The matrix is generated by Sandia National Laboratories using an algorithm called DELSOL, written in FORTRAN (Ehrhart et al, 2013). Inputs to DELSOL differ slightly from properties of the Solar Two plant, which will cause an error.…”