Global steelmaker Tata Steel is very excited about its new partnership with global firm RWE to supply offshore floating wind turbines to the Celtic Sea. If all goes according to plan, these won’t be any old wind turbines. RWE is also one of those behind the experimental floating turbine design “TetraSpar Demonstrator”, which is currently undergoing tests off the coast of Norway.
More steel for more offshore floating wind turbines
The steel industry is heavily focused on renewables – not only using them for energy, but also producing clean energy infrastructure. One such example is the recent news that Nextracker and BCI Steel are reviving a dormant steel mill in Pittsburgh to manufacture trackers for the utility-scale solar market.
The Tata Steel news hasn’t caused as much excitement over here across the pond, but it’s great news for the Welsh economy and the more than 5,000 workers directly employed at Tata Steel plants across the country.
RWE plans to power a number of gigawatt-scale floating wind turbine projects in the Celtic Sea and is apparently counting on Tata to help deliver the goods. The new deal will see RWE and Tata work together to provide advice and technical assistance to the Crown Estate, the agency that manages marine and land assets in Wales.
What is this TetraSpar you speak of?
CleanTechnica has dabbled in the waters of the TetraSpar Demonstrator project here and there over the years, so now is a good time to catch up.
RWE is working with Shell, TEPCO Renewable Power and Stiesdal Offshore Technologies on the demonstration project, which includes one 3.6 megawatt floating turbine. The platform was built in the port of Grenaa in Denmark and towed along with the turbine to Norway’s METcentre test center about 10 kilometers offshore.
As described by Shell, TetraSpar was fully commissioned last December and produces power on an autopilot system.
Of interest to steelmakers and other wind industry stakeholders, Shell touts a number of features that enable a “leaner manufacturing, assembly and installation process with lower material costs:
- Quick assembly of modules on the quayside, requires no welding and no special dock equipment
- Launch using a semi-submersible boat, followed by rapid installation of the turbine using a conventional offshore crane
- Safe deployment of the keel when towing to a location with sufficient depth, making the TetraSpar Demonstrator the world’s first girder foundation capable of deployment from an ordinary harbor in shallow water.
“The demonstration project showed that Stiesdal’s ‘Tetra’ concept remains on target to offer important advantages over existing floating wind concepts with the potential for leaner manufacturing, assembly and installation processes and lower material costs,” reiterates Shell.
Wait, who is Stiesdal?
The engineering company Stiesdal Offshore is behind all of this. If that name doesn’t ring a bell, join the club. Apart from a passing mention in reports of Tetraspar now and then, Stiesdal flew under CleanTechnica radar, so now is a good time to catch up.
Stiesdal has some interesting points to add to the conversation about offshore floating wind turbines.
Compared to the conventional single-pilot fixed turbine offshore wind farm design, the floating array took off slowly. This is partly due to the relatively high cost of anchoring systems and flexible cables. However, Stiesdal points out that floating wind potentially has some key cost advantages when it comes to large-scale production and deployment.
“Floating structure can basically be made as one size fits all,” explains Stiesdal. “Taking into account differences in turbine size, the same floating foundation can be used all over the world. This is a significant standardization benefit compared to today’s practice, where different projects have different bases.”
One size fits all floating dovetails from turbine manufacturers who also supply identical models worldwide.
In addition, the design of fixed turbines requires the workforce to spend more time at sea. Floating wind turbines can be assembled in port, which is an important advantage. Naval installation vessels aren’t a dime a dozen, and so are naval crews. The advantage of the construction on the left side is great.
Stiesdal also notes that impact noise in conventional fixed, monopile construction is an environmental hazard. Floating wind anchors are not without impact, but technology is improving and providing a solution to the noise problem.
TetraSpar difference
Others have also noticed the benefits, which explains why the floating wind area is taking off like hotcakes. Stiesdal aims to break out of the pack by focusing on standard industry processes that enable high volume and low cost.
“The Tetra base is the first fully industrialized floating offshore concept in the world. It is based on factory-built modules assembled on the waterfront with maintenance-free joints that form a complete foundation,” explains Stiesdal. “The use of mass production methods in a factory environment reduces production hours by 85-90%, achieving a lean, fully industrialized floating foundation concept with low material costs and rapid assembly.”
“The Tetra concept can be implemented in a number of variants and adapted to any turbine size and water depth and is well suited to siting requirements,” they add.
Onward and upward for floating wind turbines
For a relatively new field, floating wind certainly took off quickly. We guess that Stiesdal is already considering the idea of mounting several turbines on one platform. Also in the mix are improvements to anchor systems.
Of course, no mention of offshore wind is complete without a mention of green hydrogen, especially when it comes to Shell. It seems that RWE has it in its hands as well. The company has already set up a decarbonisation center in South West Wales called the Pembroke Net Zero Centre.
RWE has a 60-year history in the locality, starting with an oil-fired power plant and switching to natural gas after 2010. Compared to the oil burning phase, natural gas looks like it will have a short run.
Although RWE notes that the highly efficient gas plant has “the lowest CO2 the output intensity of any gas-fired power plant in the UK,” the company is eyeing another move into decarbonisation territory.
The game plan may include attaching a carbon capture device to a gas-fired power plant, at least in the short term. However, the Pembroke plan also seeks a “groundbreaking” electrolysis facility of 100 to 250 megawatts to produce green hydrogen.
This is quite ambitious, considering that most electrolysers today are rated at around 20 megawatts. On the other hand, the electrolysis field appears to be moving rapidly into triple digit territory.
Apparently we haven’t seen anything yet. RWE expects this system to lead to gigawatt-scale production of green hydrogen at some point in the future, most likely with the help of upcoming gigawatt-scale floating wind turbine projects in the Celtic Sea.
Follow me on Twitter @TinaMCasey.
Photo: TetraSpar offshore floating wind turbine under construction, courtesy of Stiesdal.
Check out our brand new A guide to e-bikes. If you are curious about electric bikes, this is the best place to start your e-mobility journey!
Do you appreciate the originality and reporting of CleanTechnica? Consider becoming a CleanTechnica member, supporter, technician or ambassador – or a patron on Patreon.