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Project Submission: Integration of Oscilay™ Cables with Subsea Substations
Aker Solutions is currently running a project to integrate its dynamic inter-array cables with subsea substations to deliver a sustainable and low-cost solution for the offshore wind market.
Using its Oscilay™ cable manufacturing technique with subsea substations, the CAPEX can be significantly reduced compared to traditional installations. Oscilay™ cables have greater machine simplicity and require fewer splices and welds, as well as offer a simpler and more cost-effective offshore installation. Combined with subsea substations, this has the potential to significantly increase the efficiency of energy transmission back to shore
One key enabling element is a 72.5kV wet mate connection system combined with our 66kV dynamic power cable. One subsea substation can have a capacity up to 300MVA and eliminate the need for a dynamic export cable. Several such stations can be used in combination for higher capacities. The key to the exceptional capabilities is simplicity and no utilities as it is naturally cooled in water. Another key part is the rigorous qualification and test regimes from the subsea industry safeguarding well tested and fit for purpose designs.
Ongoing developments are currently being undertaken in the United Kingdom and Norway with partners Benestad and ABB, and supported by the department for Business, Energy and Industrial Strategy (BEIS), Innovation Norway, and Norwegian Research Council. The ongoing development and qualification projects are due to be completed in 2024.
Project Submission: Applying BargeRack to WTIVs
Friede and Goldman Ltd. (F&G), is a naval architecture and marine engineering firm based in Houston nominated for its BargeRack technology innovation. The rapid development of the U.S. offshore wind industry is challenged by certain Coastwise Laws (typically referred to as Jones Act). One of the biggest problems is that a Jones Act compliant Wind Turbine Installation Vessel (WTIV) built in the U.S. is cost-prohibitive and requires a long lead time for construction. There are concerns that the Jones Act mandated supply chain can only support a small part of domestic wind industry expansion.
With foreseeable increasing demand in the supply chain, and to avoid a potential bottleneck in development, the industry is looking towards other scalable solutions such as WTIV feeder concepts. To overcome the often-underestimated problem of feeder vessel motions, F&G proposed a first-of-a-kind solution – the BargeRack concept applied to a WTIV. The innovation incorporates superior jack-up technology from F&G’s nearly 130 jack-up rigs built to date.
The BargeRack module is a removable L-shaped structure which serves as a dock for a feeder barge. The module is similar to a forklift concept. Outfitted with a BargeRack attachment, the installation vessel can lift the feeder barge completely out of the water and install the components directly off the stationary barge. Barge motions are thus eliminated during the installation process, yielding safe, precise, fast, and simple lifting of equipment, and extended operation windows. The BargeRack module is designed to be applicable to different WTIVs and feeder barge sizes to accommodate different WT capacities (>15MW). It has the potential to fill the supply chain gap related to the installation phase. The concept continues to attract heavy interest from installation contractors, shipyards, and wind turbine manufacturers. The concept design was granted Approval in Principle from two major Classification Societies in 2022 and is currently patent pending.
Project Submission: Tapered Spiral Welding for Automated Tower Manufacturing Technology
Traditional tower manufacturing processes cannot efficiently scale to keep pace with the growth in offshore wind turbine size. Furthermore, the U.S. has insufficient domestic tower manufacturing supply capable of producing towers at the sizes required by today’s offshore wind turbines. Rather than investing in traditional tower and monopile manufacturing facilities, and their inherent limits on wall thickness and section size, the U.S. market should shift to advanced manufacturing technology that can scale easily to produce towers and piles for many generations of future turbine designs.
To this end, Keystone Tower Systems has developed tapered spiral welding, an automated tower manufacturing technology that enables highly efficient production of welded tubular steel towers. This technology is based on spiral welding, a proven process for producing cylindrical pipe and pilings that has been adapted to accommodate the tapered diameter, variable wall thickness, and high manufacturing quality required for wind turbine towers. Keystone has extended tapered spiral welding to flexibly scale to any wall thickness by employing a multi-wrap process, in which towers are produced by bonding successive layers of spiral welded steel into a steel composite structure. Multi-wrap spiral welding can produce any wall thickness, enabling the use of a single factory for any turbine size.
In this NOWRDC project, Keystone is partnering with major offshore wind turbine OEMs (GE and Vestas), major offshore wind developers Ørsted and Equinor, structural/civil engineering experts at Johns Hopkins and Northeastern University, welding experts at EWI, and the wind installation vessel manufacturer GustoMSC, to investigate the potential and feasibility of multi-wrap steel wind towers, specifically in offshore applications. The goal for the project is to affirm structural and economic performance for Keystone’s spiral-welding technology in offshore applications, as well as study and compare their experimental multi-wrap technology to their standard tower findings.
Validating the scaling capabilities of the spiral welding technology to offshore towers is complex. This challenge is overcome through a combination of numerical models and physical tests to demonstrate sound performance in novel buckling and fatigue modes. The advantages of spiral welding over traditional tower manufacturing are significant and merit the rigorous pursuit of these innovative technologies. Advantages of spiral welded towers include increased throughput, reduced land area requirement, tighter manufacturing tolerances which impart the same structural strength with reduced steel mass, and the possibility for single-section construction that eliminates the need for expensive and high maintenance intermediate flanges.
This has important implications for all offshore wind developments as it allows for flexibility, optimization, and cost savings in structural steel, project production rates, and localization/domestication of steel production, labor, other supporting supply chains, and transport services.
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At the Oceantic Network, formerly known as the Business Network for Offshore Wind, our driving purpose is to inform, coordinate, and mobilize human ingenuity, enterprise, and labor to take advantage of the urgent need to tap the vast renewable energy resources that lie offshore in the world’s oceans. The collective, coordinated efforts of our members equip communities and nations to accelerate the transition to clean energy and create economic opportunities.
November 9, 2023
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