Solar updraft tower - structural optimisation under dynamic wind action

Abstract

A solar updraft tower is a type of power plant which uses solar irradiation to generate electricity. It consists of three elements: a solar air collector, wind turbines and a chimney. The proposed concepts for this chimney schematise it as a 1-km-tall reinforced concrete shell, which are vulnerable to resonance induced by storm actions. This paper presents a method to optimise the pre-existing designs for the chimney of a solar updraft tower. A finite element model has been created and analysed to find out which key problem areas can benefit from improvement. A design tool, based on this finite element model, is presented which enables the user to analyse multiple chimney configurations at once. A multi-objective optimisation process reveals that the key problem areas can be optimised as follows: changing the aspect ratio of the rings ensures that the chimney is fully loaded in compression. An increase in the throat height further improves the reduction of tension and the first eigenfrequency. A reduction in wall thickness at the top of the chimney improves the first eigenfrequency while also reducing material use. Finally, the stiffening rings at the bottom serve little to no purpose. Removing those rings leads to a reduction in material use while some of the material gained can be used to increase the dimensions of the top rings, consequently improving the second eigenfrequency and reducing tension.