Enhancing solar tower competitiveness with star-shaped receivers

Star-shaped receivers represent a novel receiver concept to increase performance and reduce cost of solar tower plants, boosting the competitiveness of these renewable and dispatchable power production technology. This article presents a comprehensive analysis of star-shaped receivers, which, due to their unique geometry, provide lower optical and thermal losses, increased lifetime, and reduced construction and maintenance costs. The article describes methodologies for assessing optical and thermal performance, pressure drop, creep-fatigue lifetime, wind load, and capital and operating costs of star receivers. Specifically, optical analysis is performed using ray-tracing simulation tools while tailored numerical models are implemented in MATLAB to investigate thermal, mechanical and economic aspects. The proposed methods allow to estimate the maximum receiver size that can withstand wind loads for a given location and optimize the design of this innovative receiver through a constrained parametric procedure based on Levelized Costs of Heat (LCOH) minimization. Results show that the cost of the star receiver can be up to 75 % cheaper than the corresponding Gemasolar-like cylindrical receiver with the same design thermal power. This cost reduction results from the adoption of fewer number of tubes and less expensive material as 800H instead of H230. Overall, the optimal plant configuration has a higher thermal energy collected by around 5 % annually, resulting in a 30 % reduction in LCOH with respect to Gemasolar-like cylindrical receiver case.