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Demonstration of Integrated Solution for offshore Tocardo Tidal power plants.

Periodic Reporting for period 2 - InToTidal (Demonstration of Integrated Solution for offshore Tocardo Tidal power plants.)

Reporting period: 2017-10-01 to 2019-12-31

InToTidal focused on the supporting technologies and methodologies used to simplify and optimise the installation of floating tidal stream turbines.

These turbines can provide predictable, reliable power to the electrical power grid, or to standalone power systems. A significant element within the deployment costs of these devices are the systems used to hold the devices in place – the anchors and moorings, as well a way to protect the umbilical used to send the power to the shore. These formed individual work packages within the project.

A single turbine platform was used by Tocardo to demonstrate many of the principles of the project work packages as a stepping stone towards a larger Universal Floating System (UFS) which was intended to house 5 turbines. This single turbine deployment at EMECs tidal test site in the Orkney isles provided information used by project partner IFREMER in their scale model testing, looking into the design of the full scale moorings.

External pressures meant that the development of this UFS fell outwith the timeline of the project and the resources of the project were refocused on one particular work package that developed a submersible drill rig for the installation of rock anchors.
A single rock anchor can replace many hundreds of tonnes of gravity moorings, and is seen as the next step in reducing the cost and environmental impact of mooring large renewable energy structures in rocky seabeds.The potential economic and environmental savings are considerable, and are hoped to provide a step change in the cost of deploying tidal turbines, as well as cost reductions in other offshore industries such as wave energy, offshore wind and aquaculture.

Leask Marine led the work package, designing and fabricating a bespoke rig that was displayed as the centrepiece of All Energy 2019 in Glasgow. EMEC prepared a cutting edge monitoring system to capture the acoustic signature of the drill in action.
The InToTidal project is a tidal energy power plant project to demonstrate at full-scale (via sub-system testing and duration complete system testing) that the LCoE (Levelised Total Cost of Energy) of free-flow tidal energy can give a positive commercial business case for the tidal feed-in tariff regimes currently applicable. This is achieved by a combination of significantly improving the energy yield of the turbines, reducing costs for mooring and anchoring systems and providing a highly reliable power export umbilical solution. The demonstration project is comprised of the sub-objectives that together support the main objective. The progress on these sub-objectives is as follows:

1. Validation testing of turbine energy yield enhancements.
• New control system tested in sheltered water test programme, elevated load factors achieved

2. Installation and validation of a low-load mooring system.
• Gravity based system using synthetic mooring lines demonstrated in sheltered water testing. Ease of installation and resilience of moorings proven

3. Installation and validation of low-cost anchoring systems.
• Geotechnical and design requirement report produced
• Submersible drill rig design finalised
• Anchor development work completed to create an industry leading offering - the Stratalock
• Drill rig displayed at All Energy 2019 as main focus of project dissemination
• Detailed environmental monitoring plan developed for the characterisation of the acoustic output of the drill rig

4. Installation and validation testing of maintenance-free dynamic umbilical system.
• Umbilical handling strategy identified, and scale test plan created

5. Validation of installation and service methods for a floating tidal turbine foundation solution.
• Installation and maintenance of demonstration scale device in sheltered water shown to be cost effective and efficient

6. Full circle correlation of modelling, scaled tank testing and full scale testing to improve future design models.
• Several successful tank test programmes have been completed, validating much of the conceptual work done by project partners in terms of moorings and design of UFS
"The project had several successful outcomes:

Economic
•The development of a replacement for gravity anchors and gravity based foundations is well placed to present significant savings to the marine energy convertor sectors, and also provide cost effective options for aquaculture. Avoiding the need to deposit thousands of tonnes of metal and concrete on the seabed is both economically and environmentally beneficial
• Advanced control algorithms allow for the precise control of a tidal turbine. Considerable improvements in this area of research were achieved by Tocardo, which will feed into future projects and commercial enterprises, strengthening the entire sector
• Extra staff have been taken on by Leask Marine to facilitate the fabrication and development of the Submersible Drill Rig, enhancing the local economy. These staff have won national level awards for their work on this project.

Technology
• The Submersible Drill Rig that Leask Marine have developed is beyond state of the art, providing a remarkably tailored solution for a challenge felt by all tidal developers. The large diameter piles, installed from cost effective ""multicat"" style vessels offers a step change in the availability and suitability of the rock anchor approach.
• Synthetic moorings are a relatively new concept in the sector, and this project provided a selection of useful data points regarding the operability and resilience of the system.

Societal
• InToTidal has provided a valuable additional to the toolbox that marine energy developers can use for the roll out of clean energy for Europe and wider into the rest of the world."
EU commission inspection of TFS at EMEC test site
Scale model of UFS undergoing flume tank testing at Ifremer
Artists impression of UFS