AZTERLAN Technology Centre collaborates with the companies FIHI FORGING INDUSTRY, S.L, GRI Renewable Industries and with TECNALIA in the development of more resistant flanges, with optimized designs for the installation of large offshore wind turbines of greater power capacity.
Undoubtedly, wind energy is called to occupy a preferential place in the energy mix of the future emissions-neutral Europe of 2050. Globally, forecasts suggest that the wind energy industry will generate 17,000 GWh in 2050 (a capacity 15 times greater than in 2018 when it was 1,100 GWh) with an installed electricity generation capacity of up to 5 TW. Due to the lack of space limitations and a more consistent power generation, offshore wind farms will be a strong bet of the energy sector in the coming years, with a clear tendency to increase their power.
With such ambitious growth targets, the rapid start-up of wind farms, the increase in their capacity to generate energy and the optimization of the performance of wind turbines are the key aspects that the sector must deal with. Thus, the trend points towards creating structures of greater dimensions and power capacity, at the same time the industry seeks for optimizing its production chain and the installation process of the towers, component by component. In this context, wind flanges are a critical structural element, especially in the field of offshore wind farms.
To develop a new generation of flanges for offshore wind turbines, the manufacturer of components for wind turbines FIHI FORGING INDUSTRY, S.L. leads the NEXTFLANGE project, together with the company GRI Renewable Industries, the AZTERLAN Metallurgy Research Centre and TECNALIA (both members of BRTA), aimed at the development of new steels and manufacturing routes for disruptive flange designs, with the ultimate goal of achieving excellence of product structural efficiency.
In the words of AZTERLAN researcher Itziar Berriozabalgoitia, an expert in Forming Technologies, “the current materials used to manufacture flanges do not have the mechanical resistance demanded by the change of scale that is taking place in the power of the wind towers. This increase in power means that the stresses that the flanges must withstand keep increasing and, therefore, it is necessary to develop new steels, always under the limitation of the standards that rule the manufacturing and implementation of flanges (UNE EN 10025), to ensure proper performance”. For this reason, in the field of materials “we will start from S355NL steel, a material used in the wind energy sector, from which we plan to develop evolutions in terms of chemical composition, that will improve their resistance and toughness”.
However, the project team is aware that “acting exclusively on the chemical composition of the material is not possible to cope with the demands of this application”. For this reason, “we will also have to work on the development of new heat treatments and welding routes, mainly due to the differences in weldability and thermal behavior of these steels to meet the high demands of the sector.”
New wedged flange design to overcome the limitations of bolted joining systems
In addition to working on the characteristics of the manufacturing materials, NEXTFLANGE FIHI will also evaluate the reliability of new coined connection design concepts compared to the one (bolted joints) traditionally applied by the sector. “The current bolted L-flange system does not endure the increase in turbine weights that magnification of size and power require.” The new coined joining system will allow overcoming this limitation, favoring stronger joints; in this case, “the main challenge relies on developing an advanced manufacturing route for this disruptive design that, in addition, will allow offering a competitive cost for the sector”.
The NEXTFLANGE project started in 2022 and it is scheduled for completion during the first quarter of 2025. The NEXTFLANGE project (CPP2021-008783) is funded by MCIN/EIP/10.13039/501100011033 and the European Union’s NextGenerationEU/PRTR.
