High temperature central tower plants for concentrated solar power: 2021 overview

Among the diverse technologies for producing clean energy through concentrated solar power, central tower plants are believed to be the most promising in the next years. In these plants a heliostat field collects and redirects solar irradiance towards a central receiver where a fluid is heated up. Afterwards, the same fluid or eventually another one heated in a heat exchanger develops a thermodynamic cycle that produces a mechanical power output, transformed in electrical energy through an electrical subsystem. Quite high temperatures can be reached in the solar receiver, above 1000 K, ensuring a high cycle efficiency. This review is focused to summarize the state-of-the-art of this technology and the open challenges for the next generation of this kind of plants. An actualized review of the plants working nowadays as well as the plants under development and research projects is presented. Updated thermo-economic data are collected in a comprehensive way. Each of the subsystems of a typical plant are surveyed, putting the emphasis on the more relevant research lines and the issues to be solved in the next years. Heliostat field margin of improvement, high temperature receivers and the most suitable thermodynamic cycles to take advantage of high temperature heat are detailed. Thermal storage and hybridization concepts are also surveyed. It is stressed the importance to design the plant as a whole, optimizing subsystems and their coupling to improve overall plant performance. Finally, a prospect for future R&D in this field is performed.