SMARTY - Supergen MARrine TechnologY challenge

Any structure exposed to breaking waves, be it a simple breakwater or a complex and expensive marine energy machine, will be exposed to high wave impact loads as overturning wave crests slam into it. The violence of the motion of the water surface as waves break are well-known to surfers who seek out such conditions. Marine renewable energy devices will be hit by the most violent storms that nature can produce, yet they are required to produce significant power when the weather is benign and the waves relatively small. This dichotomy can result in expensive failures such as that of the Osprey, a 2MW wave power prototype device located off the north coast of Scotland, which was damaged and sank in a storm. If marine renewable energy is to play a significant role in meeting the energy requirements of the the United Kingdom, all energy extraction devices must survive for many years and many large storms without damage. Hence accurate design methods are required to estimate the peak hydrodynamic loads occurring in such storms.

This project explores the science and engineering required to ensure that renewable energy devices survive extreme conditions, and seeks to identify the upper limit of device operations in less severe conditions. Key to making a significant advance in survivability is understanding how steep and violent waves behave on significant currents. Both wave power machines and marine current turbines are likely to be located in relatively shallow water with relatively fast tidal currents, obviously for tidal turbines this is a virtue! If the current is fast and the water shallow, there will be considerable resistance to the flow close to the sea-bed and less further up towards the surface. Thus, the current is likely to be highly sheared and very turbulent. Add on top of this bulk flow violently overturning steep waves and it is clear that the water will be moving around very fast in local regions. The first part of this project is to characterize the statistics of waves and how this varies over time for decades to decades. Next the waves are combined with sheared currents. Then models of marine renewable energy devices will be exposed to such violent combined wave and current events and the forces measured. Finally we aim to develop and test force computer based computational methods for assessing loads.

The overall output from this research project will make an important contribution to removing blocks limiting and slowing down the large-scale implementation of marine renewable energy.

The SUPERGEN Marine challenge call on 'Accelerating the deployment of marine energy (Wave and Tidal)' stresses the need to address the issues which are holding back the deployment of marine energy, some of which were highlighted by the scoping workshop in March 2011 (attended by Dr Drake, one of the partners in this proposal).

This proposal is aimed directly at the part of the call 'Understanding extreme loading events and impact on devices and arrays'. So our work packages are constructed to tackle this problem directly via a combination of high quality laboratory experiments and numerical simulations. We expect the outputs from this work to have a major impact on marine renewable development and coastal and offshore engineering more broadly.
There remain serious scientific questions to be addressed as to the behaviour of steep and breaking waves on sheared currents, and the loads which such massively unsteady turbulent flows exert on any marine renewable systems. The SMARTY project will develop new experimental techniques using state of the art facilities, better than industry standard analysis methods in combination with strong stakeholder engagement through an advisory group meeting with the participants on a regular basis, all aimed at achieving significant improvements in device survivability and utilization.

Engagement with the advisory group will provide natural knowledge transfer. The active participation of Lloyds Register will provide guidance from a regulatory and certification viewpoint. BP will bring their expertise in physical oceanography and offshore structural analysis, as shown by the statement of support from their group chief oceanographer. The support from Peter Fraenkel from Marine Current Turbines shows that device developers will buy into our research programme. Support from EPD and E-ON shows that energy utilities believe we have something important to offer, as does that from Garrad Hassan as representative of consultants in marine renewables.

Dissemination activities will include publication of the research findings in leading international journals, and participation by SMARTY researchers in international conferences and UK meetings. Engagement with learned societies will occur through the Society of Underwater Technology via their SUTGEF group, currently chaired by the P-I Prof Taylor. The experiments at UCL will make excellent material for university open days etc. to engage the interest of visiting school groups etc. The work in this proposal will be tightly integrated into the rest of the ongoing SUPERGEN activities via the hub in Edinburgh.

Further details are given in the Pathways to Impact statement (attached).