Scotstream is developing the Spintral floating structure and mooring system that can be used for Wind and Tidal Stream applications.  The base case configuration uses a 10 MW Wind Turbine and 5 off 1 MW Tidal Stream turbines to provide 15 MW Capacity.

The semi-submersible weathervaning floating structure uses a hybrid single line mooring system.

The structure can also be used for Wave energy and Floating Solar energy applications.  Hydrogen production and storage facilities can also be integrated into the floating structure.

The floating structure is also designed so that it can have an integrated offshore fish farm.

The simple floating structure and mooring system can be used for a range of renewable energy application and for aquaculture.

All of the Scotstream Technology is available under a licencing agreement.

One of the main features is the wind turbine design – the Ballast Tower, where the heavy generator and gearbox are relocated from the nacelle at the top of the tower to a machinery room located below the tower base.  A vertical drive shaft and gearbox arrangement transmit the power from the blades down to the generator.  The main benefit of this configuration is that the stability of the floating structure will be improved by about 25% and therefore the structure and mooring system size can be reduced considerably.  Scotstream Ballast Tower Brochure

The floating wind industry is at an early stage in its development.  More than 75 floating wind concepts have been proposed and there have been a number of first-generation systems installed and tested.  Europe currently has a total of less than 50 megawatts of floating wind installed.  It is projected that 350 megawatts of floating offshore wind will be in operation by 2022 at various demonstration projects.  The global market for floating wind is predicted to be immense.

In Scotland, the ScotWind leases are due to be released shortly.  These leases have the potential to provide up to 13.5 GW of floating wind power.

In addition, the UKCS Oil and Gas industry is in the process of transitioning from hydrocarbon generation over to net zero generation.  It is envisaged that many of the offshore installations will be powered by floating wind farms in the near future.  It is envisaged that up to 7.5 GW of power could be provided from the ScotWind lease areas in order to provide electricity to the offshore installations.

The main challenge facing the development of floating wind systems is the high Capex costs initially and then the high Opex cost during the service lifetime, resulting in a high Levelized Cost of Energy (LCOE).   The LCOE for floating wind systems is currently too high at about £250/MWh, this compares to about £40/MWh for a bottom fixed inshore wind system. Spintral Floating Wind System – Lowering the LCOE.docx

In order to reduce the LCOE the capital cost of the wind turbine, structure and mooring system will require to be considerably reduced.

The operating cost for planned and unplanned maintenance will require to be minimised.  Component replacement should be performed offshore, rather than requiring the structure to be returned to port for component replacement.   The generating capacity of the floating assembly should be maximised.  The current systems are rated at about 10 MW.  This capacity should be increased to 15 MW and then eventually 20 MW.

The Spintral system is a new floating wind system that has been designed to address these issues – in order to lower the LCOE for the industry.  The design is based on offshore oil and gas technology that has been adapted to suit the specific requirements for floating renewable systems – at a lower cost base.

The Scotstream approach is to licence the technology on a global basis. This will enable any party that is interested in developing renewable energy sites to have direct access to the technology and manufacture the devices in their own local area. This should open up the market, reduce costs and speed up implementation of the technology worldwide.