Hybrid welding reduces cost and emissions of wind turbine production by 90%
With the help of electromagnets, a new start-up can reduce the welding time of a 120m wind tower from 96 to 12 hours, while also creating cost savings of up to 90% (Image: Gabriele Rohde/Adobe Stock)
A ‘game-changing’ welding approach is being commercialised to dramatically reduce the time, energy and cost of wind turbine production.
The new approach could reduce welding times for a modern 120m steel wind tower by up to eight times – from 96 hours to just under 12 – while also reducing energy consumption from 4,000kWh to just 900kWh.
Consequently, the costs for welding could be reduced by up to 90%, while the CO2 emissions from the production of a wind tower could be reduced by as much as 90%.
In addition to accelerating the production of wind farms, the technology could also save time and money in the manufacture of cruise ships, pipelines, gas turbines, gas tanks and many other industrial structures.
Modern steel wind towers comprise welds totalling a length of approximately 700m, with steel sheets up to 30mm-thick having to be joined together in several layers.
While this is typically done using submerged arc welding, at present this can take up to 100 hours to complete. In Germany, this limits the capacity of the four remaining German production sites to about 520 steel towers per year – only around half of what the German government's expansion targets for onshore wind energy envisage.
Additional steel towers are therefore currently being brought in from abroad, mainly from China, where they can be produced particularly cheaply due to low labour costs.
Looking to help secure important competitive advantages for Germany’s wind industry, a team of scientists at the Bundesanstalt für Materialforschung und -prüfung’s (BAM’s) Wind Competence Centre have developed a way of producing steel towers significantly faster and more cost-effectively using laser hybrid welding.
Deployed since the turn of the century, laser hybrid welding uses a combination of laser beam and electric arc welding to rapidly produce welds that require little rework. It was first used in the automotive industry to join metal sheets with a thickness of 1-3mm, while the ship building industry soon followed by using it to process 10mm-thick parts.
The technique requires only a single welding layer, however so far it has only been industrially approved for sheets up to 12mm thick. This is because when welding thicker sheets, drops form from the liquefied metal underneath the weld seam due to gravity, which can both endanger the stability of the weld while also creating need for expensive rework.
In recent years, the BAM researchers have developed a solution to this long-known issue. It involves attaching a system of electromagnets to the welding zone, which by creating a so-called Lorentz force can counteract the effects of gravity, preventing drops forming at the weld seam. The innovation makes it possible to use fast laser hybrid welding to join thick steel sheets without compromising weld stability.
In a new approach to laser hybrid weldings, electromagnets are used to counteract the effects of gravity to prevent drops from forming on the weld seam (Image: BAM)
Four scientists from BAM's Wind Competence Centre are now setting up their own spin-off company to commercialise the technology, with the aim of developing it into a marketable system for industry over the next two years.
"Experts already confirm that our system could become a game changer for the wind industry," explains Fatma Akyel, responsible for R&D at the new firm. "At the same time, steel wind towers are only one field of application for our innovation. There is further potential wherever thick-walled steel sheets are joined together: in the construction of hydrogen pipelines, of containers for liquid gas or chemicals, in ship and bridge construction."
The work is being supported by the EXIST funding programme of the German Federal Ministry of Economics and Climate Action (BMWK).