1. 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

2. 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

3. Sea Trials Buoy

4. Wave Powered Navigation Buoys - 1982

5. OWC’s 2GW station Outer Hebrides

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

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

8. Oyster 1 – 2009

9. Oyster

10. 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

11. 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 kW)

12. 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

13. 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

14. 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.

15. 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