Optimization and performance assessment of Solar Towers

The present paper investigates possible strategies to improve the competitiveness of Solar Towers, considered the best option over CSP technologies. Nevertheless, many aspects still penalize the tower systems, mainly the higher installation costs and the lower energy density. The optimal design of the heliostat layout and the selection of the optimal tower height are fundamental to improve the performance of CRS. A new model for optimizing and simulating solar tower plants, based on an in-house Matlab® code, has been developed and validated. A technical and an economic optimization procedure allows to select the plant configuration with the maximum efficiency or the minimum LCOE, respectively. The case study is focused on a solar field of 6000 heliostats, corresponding to a nominal power of 100 MWe. The tower height shows a strong influence on the heliostat layout and solar field performance; however, the annual energy yield shows a nearly asymptotic behavior when the tower height is increased. An economic optimization leads to a less dense layout to limit the tower impact on the cost; a penalty in efficiency of around 6% can reduce the LCOE of more than 5%. The minimization of land utilization, saving 24% of the occupied area, has a penalization of about 8% in terms of LCOE.