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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - HYPER TOWER (Design of Hyper Tall Onshore Wind Turbine Towers)

Teaser

Summary

In order to catch the â€œ20-20-20â€ targets there is a global trend to increase the use of sustainable sources in energy production. This leads among other sustainable energy production fields, the wind energy sector to evolve in radical ways. Contemporary onshore towers become more efficient due to increased tower heights but certain structural issues arise that make the construction of taller towers difficult to realise with the traditional tubular tower configuration. This makes the development of a new tower configuration imperative for the construction of hyper tall structures. Hyper Tower addresses this particular issue of constructing more robust, economical, light-weight and safe wind turbine towers by proposing an innovative tower configuration. It provides a crucial contribution to the wind energy sector by proposing the design of an innovative self-rising wind turbine tower configuration assembled by trusses made up from innovative cross-sections. Multiple loading conditions are examined in order to reassure its safety, robustness and design life. All the problems of traditional tubular wind turbine towers are overcome and the construction of more economic, environmental friendly and robust wind turbine towers is facilitated. The projects positive impact on society is evident since through its implementation a positive transfer of knowledge was realized among the research fellow, the scientific communities and the general society where the fellowship was undertaken. The innovative wind tower investigated in Hyper Tower project is a structure that can be implemented and offer to society greener energy. The results are disseminated and are open to the public, both to the scientific but also to the industrial community.
The overall objectives of Hyper Tower project are: RO1, to provide improved understanding of wind turbine tower design; RO2, to achieve greater tower heights in parallel with material use economy; RO3, to identify the critical points where experimental and numerical results do not coincide and to provide sufficient explanation of future improvements; RO4, to shorten the data needed to perform fatigue analyses with the use of artificial loading histories and calculate the design life of the structures; RO5, to develop new methodologies in order to achieve towers with greater height and to solve the new structural problems that appear.

Work performed

To meet the research objectives the work of the project is organized in six work packages, all of which were completed successfully. All the deliverables were successfully completed and all the milestones were accomplished. As far as the results are concerned, all journal and conference publications were delivered and the researcher participated in several outreach and dissemination activities both to scientific audiences and the general public. This reassured that all the results obtained from the project were communicated and are available for the industry and the society to be taken advantage of.
The numerical analysis of tubular wind turbine towers and the identification of structural issues that arise when attempting to reach greater heights were realized. A number of 10 tubular tower numerical models, of diverse height and wall thickness were elaborated with the aid of ABAQUS software under all actual loading conditions. The finite element analysis of the novel lattice wind turbine tower configuration was completed, assessing the tower height and material use. The innovative tower configuration was compared to the classical steel tubular configuration in terms of capacity and material weight used. The overall behaviour of the tower was assessed with more than 100 numerical models and the comparative results were published in a journal paper. The numerical simulation of the novel cross-sections to be introduced in hyper-tall towers was carried out. The tower subparts were analysed in detail with regards to the best structural performance and a number of sixteen (16) full scale numerical analyses of the tower subparts were performed. The numerical analyses performed with ABAQUS software were compared with the experimental analyses of the innovative cross-sections that were tested at the UoB laboratory. The simulation of fatigue problem was performed using advanced numerical methods and artificial loading time-histories. The design life of the structure was calculated using Life Cycle Analysis in order to assess the environmental impact of wind energy structures. Training and dissemination activities of HYPER TOWER project were performed throughout the duration of the project. The twitter account and the project website were live from the very first months of the project while the researcher participated in numerous workshops, presentations in schools and the University, open days for industrial representatives held in the campus and educational activities for children held with the aid of UoB or the local STEM ambassadors community. Conference publications were presented from the first year of the fellowship and two journal publications were presented in International Journals.

Final results

The commonest structural configuration of classical horizontal axis steel wind turbine towers is the tubular tower, whose structural integrity is known but problems arise when attempting to cover contemporary energy demands by construction of taller wind turbine towers. The challenges beyond the state of the art that Hyper Tower managed to solve were: (1) realisation of wide tower bases of lattice structure, a fact that is practically impossible for solid tubular towers; (2) transportation of individual modules independent of its length which is a great impediment of tubular towers since solid parts of more than 20 meters are impossible to transport on site; (3) hoisting tower submodules to the final position with the use of micro-cranes instead of crawler cranes that are expensive and limited in availability. The self-rising idea of the lattice tower elaborated in Hyper Tower project could lead eventually to the fabrication of steel subparts that are easy to transport and assemble on site and to the replacement of any crawler crane machinery for the erection of the tower. Therefore, the delivered results of Hyper Tower project have presented a valuable alternative to the classic tubular wind turbine tower for onshore applications facing most of the contemporary issues still present in the state-of-the-art.
Potential impact: the analysed tower configuration has been investigated thoroughly taking into account all aspects of civil engineering issues and has been proved to be robust and economic both in terms of money and in terms of environmental impact. Therefore the economic impact that it may have is that it can offer more energy capacity, greener energy and in a more affordable price since the initial investment cost would be minimized. The social impact that the proposed solution could offer is evident since the energy produced by wind structures that are of less environmental impact (following the LCA results for the lattice structure) is of great environmental benefit for the society. Hyper Tower project offers a structure that can be implemented and offer greener energy to society. The results are disseminated and are open to the public, both to the scientific but also to the industrial community.