Axis Energy Projects Ltd is a firm which specialises in the design and delivery of offshore moorings and foundations including Tension Leg Buoys [TLB]. For more than 20 years with its Axis TLB™ technology, it has produced subsea structures, moorings and foundations such as floating arch systems for the oil and gas industry.
Now, Axis is bringing this expertise to the floating offshore wind [FOW] industry and has developed the ideal solution to deliver clean, sustainable energy.
Offshore wind has been developed to date in relatively shallow water, using substructures fixed to the seabed. However, 60-to-80 per cent of all offshore wind resource is located in waters of 60 metres or more in depth, where conventional fixed substructures are not economically viable, but higher wind reserves would be accessible. Solutions are therefore needed to harness the true potential of offshore wind.
Indeed, industry estimates suggest Floating Offshore Wind [FOW] could deliver 12 gigawatts of offshore wind, valued at £32 billion, by the year 2030. Furthermore, FOW benefits from faster delivery, simpler substructures, anchors and foundations, together with safer operation and maintenance and less environmental impact.
The novel Axis TLB™ system is being billed as the solution behind the delivery of floating offshore turbines. The Tension Leg Buoy is a robust, proven substructure and mooring system that provides controlled stability, roll and pitch, keeping the turbine vertical even in the most extreme conditions.
Independent numerical modelling suggests that the Axis TLB™ outperforms other designs in terms of reduction of maximum pitch. While FOW catenary moored structures are subject to movement in all six degrees of freedom, the TLB™ tethers allow roll, pitch and heave to be controlled, for the largest floating offshore wind turbines, allowing turbines to be located in optimum wind locations. This reduces the vibration loading on the turbine.
The system’s stability in operation and through the various phases of the installation process has been confirmed by hydrodynamic analyses performed by the Department of Naval Architecture at the University of Strathclyde. This independent numerical modelling concluded that the “Axis TLB™ system shows excellent dynamic properties under both operational and extreme conditions and can survive the harshest environmental condition in the North Sea”.
Some of the high-level environmental benefits of the Axis system include its relatively small seabed footprint, the lack of need for piling or jack-up vessels, and a very simple decommissioning process. Financial modelling of an entire offshore windfarm using the Axis TLB™ system has determined a levelised cost of electricity that is 30 per cent less than other FOW designs and comparable with offshore fixed installations. Future developments on design life, mass production, and material developments, will drive this further down.
With a share of 25 per cent of the forecast UK floating offshore wind market and five per cent of the global floating offshore wind export market, UK-based manufacture and supply of the TLB™ could generate a total UK gross value added per year of £280 million to £470 million in the 2030s, and £560 million to £940 million in the 2040s.
TLB™ is already drawing in support from within the industry and has been given due recognition as an award-winning piece of technology and an industry gamechanger. Because of TLB™, Axis Energy Projects enjoyed the double success of picking up the Natural Energy Award and Wind Power Award at the 13th Rushlight Awards in 2020, an awards showpiece which sought to celebrate and promote then new technologies, innovations and best practices across the whole environment spectrum for organisations throughout UK and internationally.
Photo by Nicholas Doherty on Unsplash
