Ocean Energy – A Pioneer’s Perspective Professor Trevor Whittaker FREng., FICE, FRINA, CEng. Ocean Energy – A Pioneer’s Perspective MRIA Ocean Energy Industry Forum 3rd February 2017

40 years ‘Research Excellence Supporting Commercial Development’ Wave power, Tidal stream, Coastal modelling 1976 – invention of the Wells self rectifying turbine Professor Alan Wells FRS

Sea Trials Buoy 1 - 1977

Wave Powered Navigation Buoys - 1982

OWC’s 2GW station Outer Hebrides

Q.U.B. 75kW Station 1988 - 1999 1st UK Shoreline Device Islay, Scotland 75 kW Capacity Successful Prototype

LIMPET – Voith Hydro Wavegen Ltd., QUB 1999 - 2014

Oyster 1 – 2009

Oyster 800 - 2012

Design Choices Power Take Off (PTO) Pneumatic Electrical Mechanical Hydraulic Frame of Reference Relative motion of structures Fixed or stable structures – moving water Moving structure – relative to sea bed All wave power stations are terminators but can comprise terminators, point absorbers or attenuators Water depth – offshore, nearshore, shoreline

Essential Requirements for WECs Sustainability Low embedded energy Materials which can be recycled Net positive benefit to environment Survivability Avoid extreme loads intrinsically Design for fatigue Maintainability ‘Plug & Play’ whole or part Condition monitoring (replace before failure) Weather access Discussion of technical constraints (Weight, simplicity, resource exploitability). Cost and reliability at sea No requirement for complex control systems, if it goes wrong it survives naturally. Inherent load shedding. Sophisticated control systems can also improve reliability Fundamental approach to design you can control things, e.g. a fighter aircraft will not fly without a computer on board because it is hydro-dynamically unstable, but a glider will fly itself. 1/2km2 of Oyster II deployment predicted annual average output = 1MW (=30%*3MW, 6x500kW units, spaced 20m apart along parallel contour lines 40m apart). VS. 1km2 of deepwater with annual average power output 100-200kW)

Essential Requirements for WECs Maximise capture per unit of structure Broad frequency bandwidth response Highest efficiency in most common seas Maximise PTO performance Minimise cost of station Short direct load paths Mass production of components Design for installation & removal Design for maintenance Multi resonance, slow tuning, phase control Better accommodation of variation in seas More consistent energy production throughout year Maximise use of installed capacity Generation in extreme seas at very low efficiency

Technical challenges lack of specialised marine vessels Cost and weather dependency of marine operations lack of specialised marine vessels engineering challenge of economic sea bed attachment energy harvesting from many small units which are either fixed or floating Maintenance and access Component design for harsh environment Accurate full life energy accounting and sustainability

Wave Power – The Way Forward The industry must consolidate. Too many underfunded SME’s solving the same problems independently Public & private finance spread too thinly Funding must be more strategic systems must meet the criteria of survivability, sustainability & maintainability Full scale marine test bed needed for components such as bearings, hydraulic seals, valves, connection components, moorings More collaboration on common problems Do not waste money on non starters Devices are only as reliable as the weakest components The environment and the duty cycle is extreme, off the shelve components are not designed for this Wavegen have LIMPET for testing air turbines. Similar facilities for articulated structures with hydraulic PTO needed.

In Conclusion Cost of energy more important than utilisation of resource Marine energy is a significant renewable resource Wave power - demonstrated technically but PTO not reliable Economic wave power achievable with increasing numbers of plant constructed (if the industry focuses) R&D – target common and not device specific issues resource assessment, sea bed attachment, PTO systems, operation and maintenance