“Subhub supports every stage of a tidal turbines life from integration ashore to deployment, installation and retrieval for maintenance and finally decommissioning”.
Full systems integration is conducted at the quayside. This is much safer and logistically easier than connecting up tidal turbine systems offshore. Most importantly it means the cost of deployment is substantially reduced since there is NO reliance put on large and specialist installation structures. Only harbour tugs and multicats are required which are commonly available and about 10x less expensive to anchor handlers and/or DP2 vessel and 15x less expensive to jack-ups and crane vessels.
Subhub is a fully integrated platform. That means it has everything onboard that it requires through its life. Therefore it can be deployed in a single offshore operation with very little support required from vessels. In fact, commonly available harbour tugs is all that is required to deliver the Subhub tidal platform to the tidal site.
Subhub is designed to be towed offshore in high sea states and this has been proven in the deployment of the demonstrator in near gale and rough conditions during its transit from Belfast Harbour to Strangford Lough. Commercial pressures can force schedules and having large operating weather windows is important for maintaining deployment rates and costs.
The installation/retrieval of any tidal turbine is the riskiest part of any offshore operation and this is where Subhub excels. Instead of using a heavy lift crane barge or DP2 installation vessel, which are assets lent from the O&G industry, Subhub uses buoyancy and its excellent stability characteristics when submerged to dive to the seabed. QED Naval have proven this installation and retrieval in both model and full scale.
One of the key advantages of this installation method is its simplicity, reversibility and robustness against against environmental conditions. The model and demonstrator has been proven in a broad range of environmental conditions.
Clearly retrieval for maintenance is as simple as installation and means maintenance costs can be minimised.