Reuse of decommissioned wind turbine blades in pedestrian bridges - An investigation of using wind turbine blades as structural members in pedestrian bridges

Abstract

Wind energy is currently one of the fastest growing renewable energy sources. As a consequence, the amount of decommissioned wind turbine blades are expected to increase in a near future. The blades mainly consists of GFRP. The polymer in GFRP is most often a thermosetting polymer which, due to its complex composition, is both insoluble and infusible. As a result, waste management of the decommissioned blades are difficult and currently no viable sustainable recycling method of wind turbine blades exists. This thesis aims to investigate the possibilities to reuse the blades as structural members in pedestrian bridges. The blades are lightweight and high performing components and using the blades in bridges could lengthen the blades life cycle and handle a portion of the decommissioned turbine blades. To achieve this a literature study was performed. This involved the theory of fibre reinforced plastics, the properties of the blades as well as guidelines and regulations on bridges provided in Eurocode and by Trafikverket. Together with experienced architects and engineers, different bridge concepts were developed. Based on the knowledge gained in the literature study, the concepts were evaluated in terms of aesthetics, simplicity of the construction, degree of maintenance as well as costs. The production method was also an important aspect considered as the part of the blade used in the bridge had a length of 20 m and a width of 3.6 m. The final concept was further designed and a FE-model in BRIGADE/Plus were created. The FE-model showed that the deformation requirements were met but that the fundamental frequency were below 5 Hz. Further investigations are therefore needed in order to verify the acceleration.