Optimal Design of Very Large Tidal Stream Farms: for Shallow Estuarine Applications

This project is a collaboration between SuperGen Marine, the Exeter Centre for Water Resources (Non-SuperGen), Penn State University, Aquascientific Ltd., The Danish Hydraulics Research Institute and is mentored by Garrad Hassan partners. The primary goal is the introduction of a new hybrid optimisation approach that allows the multi-objective optimal design of the layout and power loadings of marine energy farms subject to environmental impacts. It involves a new, academically highly challenging integrated analytic/numerical/experimental, approach to optimising the performance of large tidal stream energy capture farms. The specific application focus involves tidal turbines suited to operating in shallow medium flow estuaries but the technique can be applied to all types of marine energy farms. Optimisation is subject to minimising flood risk, with further environmental impacts, such as sediment transport driven outcomes, being capable of subsequent incorporation as slow timescale effects. The work complements the PERAWAT project and has key partners in common.

At present the state of the art in large tidal stream farms is the performance estimation of pre-defined large farm designs, while optimisation, requiring many performance calculations, is deemed to be computationally unrealistic for practical design purposes. The present project will overcome this barrier by employing a combination of :
(i) a new hybrid approach which describes the farm via a parameterised analytic model, that is matched to a numerical description of the estuary
(ii) a new highly efficient optimisation technique.
The model parameters, which define the optimum turbine locations and turbine loading factors over tidal cycles, are computed via the process of matching of the farm model and estuary descriptions. The new class of optimisation technique (pioneered at Exeter) based upon sampled surface functions, allows a large reduction in the number of optimisation parameters which require to be estimated. This method exploits the spatial dependencies between farm parameters and has applications far beyond the tidal stream farm problem. An important spin off from multi-objective optimisation is that it allows the unification of farm design and environmental impact which until now have been treated as rather separated issues.

The analytic and computational work will draw on a body of on going work at Exeter including existing experimental data on model and field trial 10kW scale near surface turbines obtained by Exeter/Aquascientific Ltd. This will be enhanced by an experimental study at Edinburgh. This will investigate (i) arrays of many tens of turbines, (manufactured in injection moulded kit form) and (ii) highly detailed interactions between small groups of large models in the new All Waters test tank. Of particular importance will be information on the relationship between power absorption and turbine geometry and on turbine interactions.

The outcomes of the work will be a combination: of new science and practical techniques that make the development of follow on tools for large scale tidal stream farm design optimisation realistic, plus the dissemination tools required to rapidly and effectively deliver these to the maine renewable energy community. This will impact on: investor/industrial provider confidence, and on the tidal stream research community, allowing the subsequent creation of a range of practical design tools for helping deliver 20:20 and 20:50 renewable energy targets. Garrad Hassan will mentor the project and undertake a due diligence study on the work for the purposes of dissemination to the wider stakeholder community.

The project includes a set of processes and dedicated events aimed at enahancing the operation of the SuperGen Marine consortium and promoting effective pathways to impact and has been planned explicitly around future research vissions of SuperGen.

Areas for Impact: The key areas for broad based (non research community) impact of research delivered under the proposed bid are: (i) investor confidence, (ii) industrial confidence in the commercial viability of tidal stream energy and hence (iii) fostering an internationally strong UK tidal energy industry, renewable energy and planning policy, (iv) political/public confidence in value for money and low environmental impact, (v) internationalisation and (vi) professional development of the next generation of appropriate tehcnical staff. The pathways to impact are designed to affect all these areas.

Overall Policy: Underpinning impact is the delivery of high quality science based upon standard outputs in the literature and conferences. The dissemination of these outputs is the remit of Pathways to Impact.
Having a world leading renewable energy consultant, Garrad Hassan (GH), as project mentor, with its network of contacts and interests connecting to all the cited areas for impact provides one key pathway. This role of GH will considerably accelerate the practical application of the science deliverables, which typically only occurs post project. A primary tool in this acceleration will be a professionally published Due Diligence Report on the work prepared by GH and suitable for broad based dissemination to decision makers. This will provide a critical users perspective on the potential impact of the new techniques developed within the project.
A second major set of pathways derive from the scope and reach of SuperGen Marine. This encompasses: its international research record, the EPSRC assigned role as the leaders in UK marine renewable energy research and the doctoral training centres. Added to this already strong base will be the incorporation into SuperGen of the outreach practices developed by the PRIMaRE Research consortium, whose brief from the South West Regional Development Agency was very close ties with industry and direct industrial assistance. This brief fostered a range of workshops, industry days and management support practices designed to build partnering relationships and disseminate research.

Internal Communication: The SuperGen Marine senior management has a responsibility to directly advise the research funding councils and government policy makers. Thus a very important issue will be providing these people with appropriate internal briefing documents on the outputs of the proposed project.

Research Staff Development: The junior research staff will constitute an important resource in the future development of marine renewable energy and so their professional development is a critical pathway to impact. To aid this end not only will the usual training schemes be made available but as far as possible the junior staff will be encouraged to become "the face of the research" to the stakeholder community.

Substantial External Events: In addition standard academic pathways and the feeding into the existing SuperGen and PRIMaRE dissemination pathways described above some specifically costed events are planned:
1. Targeted day briefing sessions with organisations who operate their own large proven dissemination networks. The first is aimed at NGOs including: the EPSRC established Electrical Supply Research Network, RenewableUK Marine Strategy Group. Marine Renewable Energy Research Advisory Group, the Scottish Advisory Group on Marine and Coastal Strategy. The second is directed at government sponsored agencies, including: DECC, DEFRA, EPSRC, The Carbon Trust and The Environment Agency.
2. A specific Stakeholder briefing Day aimed at the wider community touched by marine renewable energy.