Global steelmaker Tata Steel is excited about its new partnership with global firm RWE, which aims to bring floating offshore wind turbines to the Celtic Sea. If all goes according to plan, these won’t be just any old wind turbines. RWE is also one of the heavy hitters behind the experimental ‘TetraSpar Demonstrator’ floating turbine design currently being tested off the coast of Norway.
More steel for more offshore wind turbines
The steel industry is seriously turning to renewable resources – 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 defunct steel mill in Pittsburgh to produce trackers for the utility-scale solar market.
The Tata Steel news hasn’t caused much excitement across the pond, but it’s big news for the Welsh economy and the more than 5,000 employees directly employed by Tata Steel’s facilities across the country.
RWE is planning to deliver a number of gigawatt-scale floating wind turbine projects to the Celtic Sea and appears to be counting on Tata to help deliver the goods. The new deal will see RWE and Tata collaborate on management and technical support for Crown Estate, the agency that manages offshore and onshore assets in Wales.
What is this TetraSpar you speak of?
CleanTechnica has dipped into the waters of the TetraSpar Demonstrator project here and there over the years, so now is a good time to catch up.
RWE has partnered with Shell, TEPCO Renewable Power and Stiesdal Offshore Technologies on a demonstration project consisting of one 3.6 megawatt floating turbine. The platform was built in the port of Grena, Denmark, and towed with the turbine to the Norwegian METcentre test site, about 10 kilometers offshore.
As described by Shell, TetraSpar has been fully operational since last December and has been generating power on autopilot.
Of interest to steelmakers and other wind industry stakeholders, Shell lists a number of features that “provide a leaner manufacturing, assembly and installation process with lower material costs:
- Quick dock assembly of modules with no welding or special docking facilities required
- Launch using a semi-barge, followed by rapid turbine installation using a conventional dry crane
- The secure placement of the keel when anchored at sufficient depth makes the TetraSpar Demonstrator the world’s first spar foundation capable of deployment from a conventional, shallow-water dock.
“The demonstration project showed 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 lower material costs,” Shell reiterates.
Wait, who is Stiesdal?
The engineering firm behind it all is Stiesdal Offshore. If that name doesn’t ring any bells, join the club. Apart from one side mentioned here and there in the Tetraspar news, Stiesdal was flying under the ship. CleanTechnica radar, so now is a good time to catch up.
Stiesdal has some interesting points to add to his talk about offshore wind turbines.
Compared to conventional, monopile stationary turbine offshore wind construction, the floating field has risen slowly. This is partly due to the relatively high cost of docking systems and flexible cables. However, Stiesdal notes that floating wind has some major cost advantages in terms of potentially high-volume production and deployment.
“A floating structure can essentially be designed as a one-size-fits-all,” explains Stiesdal. “The same floating foundation can be used all over the world, allowing for differences in turbine size. This is a significant standardization from today’s practice of having different foundations for different projects.”
One size fits all floating dovetails with turbine manufacturers offering the same models worldwide.
In addition, fixed turbine construction requires the workforce to spend more time at sea. Floating wind turbines can be assembled in port, which is an important advantage. Offshore installation vessels are not a penny, nor are offshore crews. The advantage of port construction is great.
Stiesdal also notes that the percussion noise involved in conventional fixed, monopile construction is an environmental hazard. Floating wind anchors are not inefficient, but technology is improving and they are addressing the noise problem.
Others have pointed out the advantages, which explains why the floating wind field takes off like hotcakes. Stiesdal aims to break out of the pack by focusing on standard industrial processes that enable high volume and low cost.
“The Tetra Foundation is the world’s first fully industrialized floating offshore concept. It is based on factory-made modules with maintenance-free joints assembled overboard to form a complete foundation,” explains Stiesdal. “The application 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 can be adapted to any turbine size and any water depth and is well suited to localization requirements.”
Onward and Upward for Floating Wind Turbines
Windsurfing for a relatively new field has certainly started quickly. We guess that Stiesdal no longer condones the idea of installing multiple turbines on one platform. Improvements in anchorage systems are also part of the mix.
Of course, no talk of offshore wind is complete without a mention of green hydrogen, especially as it pertains to Shell. RWE has it too. 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 field, starting with an oil-fired power plant before switching to natural gas after 2010. It seems that natural gas will run for a short time compared to the burning phase of oil.
Although RWE notes that the high-efficiency gas plant “has the lowest CO2 intensity power of any gas plant in the UK,” the company is eyeing a further push into decarbonisation territory.
The game plan may include connecting a carbon capture facility to a gas-fired power plant, at least in the short term. However, the Pembroke plan also targets a 100 to 250 megawatt “pathfinder” electrolysis plant for green hydrogen production.
Considering that most electrolysers today operate at around 20 megawatts, this is quite ambitious. On the other hand, it appears that the electrolysis field is rapidly moving into triple-digit territory.
Looks like we haven’t seen anything yet. RWE expects the pathfinder system to pave the way for gigawatt-scale green hydrogen production at some point in the future, likely with the help of future gigawatt-scale floating wind projects in the Celtic Sea.
Follow me on Twitter @TinaMCasey.
Photo: Construction of the TetraSpar offshore wind turbine continues, courtesy of Stiesdal.
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