Global steelmaker Tata Steel is thrilled with its new partnership with global firm RWE, which aims to supply offshore floating wind turbines to the Celtic Sea. If all goes according to plan, it will not be just any old wind turbines. RWE is also one of the heavyweights behind the experimental “TetraSpar Demonstrator” floating turbine design, which is currently being tested off the coast of Norway.
More steel for more offshore floating wind turbines
The steel industry has made a hard turn in renewable energy – not only to use it for energy, but also to produce clean power infrastructure. One such example is the recent news that Nextracker and BCI Steel are reviving a dormant steel plant in Pittsburgh to manufacture trackers for the utility scale solar power market.
The Tata Steel news has not generated as much excitement here across the dam, but it is big news for the Welsh economy and the more than 5,000 workers working directly at Tata Steel’s facilities across the country.
RWE plans to carry out a series of gigawatt-scale floating wind turbine projects in the Celtic Sea, and apparently relies on Tata to help deliver the goods. The new agreement will enable RWE and Tata to work together on guidance and technical assistance to the Crown Estate, the agency that manages marine and land assets in Wales.
What is this TetraSpar you are talking about?
CleanTechnica you’ve been dipping a tone in the water of the TetraSpar Demonstrator project here and there over the years, so now’s a good time to catch up.
RWE has partnered with Shell, TEPCO Renewable Power and Stiesdal Offshore Technologies on the demonstration project, which involves one 3.6 megawatts floating turbine. The platform was manufactured in the port of Grenaa in Denmark and towed along with the turbine to Norway’s METcentre test site about 10 kilometers off the coast.
As described by Shell, TetraSpar was fully operational from December last year and produced power on an automatic pilot system.
Of interest to steelmakers and other stakeholders in the wind industry, Shell lists a number of features that allow for a smoother manufacturing, assembly and installation process with lower material costs:
- Quick assembly of the modules at the quay, which requires no welding and no special port facilities
- Launch with a semi-submersible bowl, followed by quick turbine installation with an ordinary onshore crane
- Safe deployment of the keel when towed to a place of sufficient depth, making the TetraSpar Demonstrator the world’s first spar foundation capable of deploying from a normal, shallow water port
“The demonstration project has shown that Stiesdal’s ‘Tetra’ concept remains on target to offer significant advantages over existing floating wind concepts, with the potential for leaner manufacturing, assembly and installation processes, and with lower material costs,” Shell reiterates.
Wait, who’s Stiesdal?
The engineering firm behind it all is Stiesdal Offshore. If that name does not ring any bells, join the club. Apart from a side mention in the Tetraspar news here and there, Stiesdal has already CleanTechnica radar, so now’s a good time to catch up.
Stiesdal has some interesting points to add to the offshore floating wind turbine conversation.
Compared to conventional, monopile fixed-turbine offshore wind construction, the floating field was slow to rise. This is due in part to the relatively high cost of mooring systems and flexible cables. However, Stiesdal points out that floating wind potentially has some significant cost advantages in terms of high-volume manufacturing and deployment.
“The floating structure can be made essentially as one size fits all,” explains Stiesdal. “With differences in turbine sizes, the same floating foundation can be used around the world. It is a significant standardization upside of today’s practice to have different foundations for different projects. ”
The one-size fits all floating dovetails with turbine manufacturers, who also deliver identical models worldwide.
In addition, fixed turbine construction requires the workforce to spend more time at sea. Floating wind turbines can be assembled at port, which is an important advantage. Sea-going installation vessels are not a tell me a dozen, nor are sea crews. The port construction advantage is great.
Stiesdal also notes that the percussion noise involved in conventional fixed, monopile construction is an environmental hazard. Floating wind anchors are not impact-free, but the technology is improving and it provides a solution to the noise issue.
The TetraSpar difference
Others also took note of the benefits, which explain why the floating wind area rises like sweet cake. Stiesdal seeks to break out of the pack with a focus on standard industrial processes that allow for high volume and low cost.
“The Tetra Foundation is the world’s first fully industrialized floating foreign concept. It is based on factory-manufactured modules that are assembled at the quay with maintenance-free joints to form a complete foundation, ”explains Stiesdal. “The application of mass production methods in a factory environment reduces manufacturing hours by 85-90%, achieving a lean, fully industrialized floating foundation concept with low material costs and fast assembly.”
“The Tetra concept can be implemented in a range of variants and adapted to any turbine size and any water depth and is well suited for localization requirements,” they add.
Forward and upward for floating wind turbines
For a relatively new field, drifting winds certainly started quickly. We guess Stiesdal is already addressing the idea of mounting several turbines on one platform. Improvements in anchor systems are also part of the mix.
Of course, no mention of offshore wind is complete without a mention of green hydrogen, especially where Shell is involved. RWE seems to have it in hand, too. The company has already established a depolarization center in South West Wales called the Pembroke Net Zero Center.
RWE has a 60-year history at the site, starting with an oil-fired power plant before moving to natural gas after 2010. Compared to the oil combustion phase, it looks like natural gas will have a short duration.
Although RWE notes that the highly efficient gas plant has the “lowest COtwo intensity of any gas plant in the UK, ”the company is considering a further move to a decarburization area.
The game plan may involve linking a carbon capture facility to the gas-fired power station, at least in the short term. However, the Pembroke plan also envisages a “pathfinder” electrolysis facility of between 100 and 250 megawatts for green hydrogen production.
This is quite ambitious, as most of the electrolysers today clock in at around 20 megawatts. On the other hand, it appears that the electrolyte field is rapidly moving towards three-digit area.
Apparently we have not seen anything yet. RWE expects the pathfinder system to lead the way to gigawatt-scale green hydrogen production sometime in the future, most likely with the help of its upcoming gigawatt-scale floating wind projects in the Celtic Sea.
Follow me on Twitter @TinaMCasey.
Photo: TetraSpar offshore floating wind turbine under construction, with permission from Stiesdal.
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