Marine Renewable Energy Seascape

Alistair Borthwick

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract / Description of output

Marine renewable energy has a major part to play in closing the world’s energy gap and lowering carbon emissions. Key global challenges relate to technology, grid infrastructure, cost and investment, environmental impact, and marine governance.

Offshore wind turbines typically consist of three blades rotating about a hub. Although offshore wind technology is rapidly being implemented, there remain many fascinating engineering problems to overcome. These include: offshore foundations and floating support structures; alternative turbine designs based on 3D computational fluid dynamics; use of advanced materials for blades; ship manoeuvring for safe maintenance; and shared offshore platform applications (such as energy production, storage, and marine aquaculture).

Many innovative tidal stream energy devices have been proposed. An example is Salter’s cross-flow turbine, which has blades arranged vertically, supported at each end on what are rather like enormous bicycle wheels. Although tidal power assessment seems easy, the very presence of tidal turbines alters the flow field, and in turn this affects power availability. Questions surround model uncertainty, turbulence, eddies, wave-current interaction, model scale-up, and environmental impact (e.g. on marine mammals and biodiversity). High performance and cloud computing should enable three-dimensional computational modelling to become routine in future. Scale model laboratory and pilot-scale field tests complement such analysis, providing validation data and insight into the in situ behaviour of tidal turbines.

Wave energy converter technology is another thriving area in which new inventions keep appearing. Here, engineers must find ways to maximise power output, improve efficiency, cut environmental impact, enhance material robustness and durability, reduce costs, and ensure survivability. Theoretical predictions of the power generated by wave energy converters require validation through laboratory-scale physical model studies and field tests. The latest simulation methods involve wave to wire modelling of arrays of wave energy converters, which integrates wave hydrodynamics, body responses, power take off, real-time control, and electricity production.

Ocean energy output is highly variable and so energy storage is essential. Compressed air energy storage, hydrogen storage, and substitute natural gas are particularly appealing options. At MaREI in Ireland, a marine power to gas concept is under development, where electrolysis is used to generate hydrogen, which is then converted to methane to be added to the natural gas network. Marine biomass is another source of marine renewable energy, through conversion to biofuel.

Novel materials with improved strength, fatigue, durability, and anti-corrosion properties are already on the horizon. Advanced composites, such as glass-fibre reinforced polymers, are ideal for cost reduction and increased reliability.

Access to ocean energy systems is expensive and hazardous. Present and future challenges include remote monitoring, control systems, robotics for operational support, and real-time weather forecasting for predictive maintenance to ensure devices can survive in extreme sea states as they arise.

In summary, marine renewable energy has huge potential, but demanding global challenges have to be met before the seascape will give up its precious energy resources. As in the industrial revolution, a new generation of engineers is required with the ingenuity, wisdom, and boldness to meet these inter-disciplinary challenges
Original languageEnglish
Title of host publicationThe 2nd Global Grand Challenges Summit, Beijing, 15-16 September 2015
Publication statusPublished - 2015

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