Techno-economic analysis of thermochemical storage for CSP systems

The use of thermochemical materials, like redox oxides, for hybrid sensible/thermochemical storage in solar tower plants can potentially reduce the LCOE and make such plants more competitive. For the techno-economic system analysis, three candidate redox materials were analyzed for their cost reduction potential: cobalt-based, manganese-based and perovskite-based oxide materials. As reference process the use of inert commercial bauxite particles (sensible-only storage) was considered. A CSP plant with a nominal power of 125 MWe and a storage capacity of 12h was assumed for the analysis. Cost factors influenced by the material selection are storage cost, steam generator cost and particle transport system cost. Based on total system cost and annual electricity generation, the LCOE was calculated. The results of the analysis show that some redox materials can significantly reduce the required storage mass and volume, while others lead only to a marginal improvement. More important is the specific cost of the redox material. Expensive cobalt-based materials result in significantly higher LCOE, while perovskite materials show potential for reduced LCOE when these particles can be manufactured at low cost. Therefore it is recommended to focus future work on this material class.