FEASIBILITY STUDY OF AN INNOVATIVE DRY-COOLING SYSTEM WITH PHASE-CHANGE MATERIAL STORAGE FOR CONCENTRATED SOLAR POWER MULTI-MW SIZE SOLAR PLANT

This work concerns the economic potential assessment of an innovative hybrid-cooling system for steam condensation in concentrated solar power plants. The system consists of an air-cooled condenser (ACC) working in parallel to a latent heat storage with phase-change material (PCM). The purpose of the hybrid system is to store some of the latent heat of steam condensation during the turbine operation and reject it at night, in order to shift a share of the cooling work and exploit the high diurnal temperature range of desert areas. System's energy and economic performances are assessed by the parametric analysis of a theoretical case study, referred to an existing solar power plant and based on historical meteorological data. The analysis considers an ideal “perfect” PCM storage system, namely with no technological barriers, and different cost scenarios. The simulation campaign outcome indicates how the innovative solution can provide just a slight improvement of the plant performance, which is anyway significant in qualitative terms since the risk of breakdowns of turbine operation during the hottest summer days is avoided. It is remarkable that the introduction of the heat storage allows for a reduction of the ACC installed power. The economic feasibility of the proposed solution follows on mainly from the comparison between the investment cost increase —due to the PCM storage—and savings—due to reduction of the installed ACC modules. The hybrid-cooling system would be an attractive alternative to standard systems if the PCM storage cost could be contained by increasing the conductivity of the PCM material. As an alternative, a cheaper heat storage technology (e.g., a water thermocline) could be coupled to an indirect-cooling system.