Tidal array cost reduction: Testing a removable nacelle design for DeltaStream Technology

The global tidal renewable energy sector is preparing to enter the growth stage and is estimated to reach £7bn by 2020
with 3712MW of installed capacity, demonstrating huge potential to become a serious contributor to the energy mix.
Transition from the current embryonic stage of the sector requires to overcome a number of technological barriers and
demonstrate that significant reduction of cost of energy is achievable in order to remove barriers to market penetration.
There is an urgent need to reduce the installation and maintenance costs of tidal stream turbines. The current project
proposes an effective wet-mate nacelle removal system for cost-effective installation and recovery. Swansea University
(SU) will evaluate of the mechanical interfacing of the removable nacelle which is to be integrated on the DeltaStream final
device assembly. This Work Package focuses specifically on the testing of the removable nacelle components through a
purpose built experimental test rig for a full scale space-weight prototype assembly. Support will also be provided to the
final device assembly including tribology investigations to establish requirements for the critical mechanical interfacing
surfaces for long term deployment.

The partnership that has been formed between industry and academia emphasizes the importance of developing an effective wet-mate system for cost-effective installation and recovery as there is an urgent need to reduce the maintenance costs of the DeltaStream system. This important design element if addressed successfully it will bring down the cost of energy and commercialisation of tidal stream technology and improve the UK's security of energy supply. The main output of SU's study will be the evaluation of the mechanical interfacing of the removable nacelle on the support base structure.
The design and full scale testing of removable nacelle components will confirm the crane-ship 'wander' engagement envelope. The operability and reliability of the wet-mate engagement process with approach and orientation tolerances will
be verified. Key areas of impact of this work will be as follows:

UK: Targeted investment in low carbon marine energy technology provides a great opportunity to deliver industry growth benefits to remote coastal communities. At the same time investment in this emerging sector will help UK companies to become strong economic contributors to UK's growth providing jobs as well as creating international export opportunities for IP based technology and services. Furthermore, investing in renewable energy will help secure future energy needs, decarbonising the UK economy and enabling the UK Government to meet their obligations by reducing domestic Green
House Gas (GHG) emissions. Commercial scale deployment of DeltaStream will have significant and beneficial impact on the UK, stimulating its manufacturing sector. Tackling the uncertainties associated with design, manufacture, operation and
maintenance of all types of tidal energy devices will benefit TEL's DeltaStream supply chain and the wider marine energy community and the UK will therefore be better placed to become a global force. The structural engineering sector will also
be a beneficiary as the existing, yet underutilised, manufacturing facilities and expertise can be applied to the design and manufacture of TEC device installations. Building these structures within the UK will have clear benefits for the future UK
economy.

Academia: Where data gathered in the project is free of commercial sensitivity, it will also be shared with the academic community for application to research activities related to other significant projects in the marine and maritime sectors.
Importantly, the research assistant will benefit from the training and experience developed through formal training, conference visits and in collaborating with industry.

Device designers: The UK leads the world with the development and deployment of marine energy devices. This project will make significant contributions to accelerate the deployment of TEC arrays. The timescale benefits during installation will reduce overall Costs of Energy (CoE) and enable developers to reduce risk and inspire higher investor confidence. The input from the industrial collaborators, TEL and MML Marine will be significant in ensuring the findings of this project are put into practice at the first opportunity.

Energy companies, Consultants and Policy makers: The deployment of TEC arrays will lead to market growth where DeltaStream is expected to capture a considerable share both in the UK and internationally. Design improvements will reduce the cost of installation and maintenance (two of the biggest cost areas for marine tidal turbines). The overall reduced CoE of the DeltaStream design especially with regard to the foundations for fixing to the seabed will allow the energy suppliers to promote a product which is attractive to customers. Policy makers and consultants will learn important lessons in identifying best practice and will be in a better position to assess the technical, commercial and financial prospects of the tidal stream technologies in UK and internationally.