Self-Erecting, In-Situ Manufactured, Wind Energy Tower, Development of Nacelle Assembly Lifting System

Utility-scale wind turbines are getting so large that transportation limitations are driving final, onsite assembly costs.  To address this problem, this project will design an apparatus for placing wind turbine components ¿ the nacelle, generator, gear box, rotor, and blades ¿ on top of an in-situ-fabricated, self-erecting tower, without using an external crane. The approach builds on UltraTall, the result of a National Renewable Energy Laboratory funded project, in which a self-erecting tower (4 sections, 1:15 reduced scale, 5.3 meter tall) was fabricated and tested. However, it was beyond the scope of that project to develop a nacelle placement apparatus. In Phase I of this project, four different design concepts for the nacelle placement apparatus were prioritized and a detailed design of the leading concept was completed. Phase II will conduct a detailed Finite Element Analysis (FEA) of the nacelle placement system (tower plus nacelle placement apparatus), develop a full scale prototype, and then test the apparatus. The plan is to erect three sections of a full-scale UltraTall tower and use the prototype nacelle placement system to lift an equivalent weight. (The construction of a full-scale wind generating system for testing the nacelle placement system is beyond the scope of Phase II.) The nacelle placement apparatus and tower sections will have a complete set of sensors, and a structural health monitoring system will be used to collect data on the structural behavior. That data will be used to validate the FEA. Commercial Applications and Other Benefits as described by the awardee: The plan for Phase III is to erect and demonstrate a full-scale wind energy system that utilizes the UltraTall tower. The site, which is on a farm in eastern Oklahoma, already has two transmission lines from utilities that have on-going wind-energy programs.