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Details of Grant 

EPSRC Reference: EP/N508640/1
Title: The capability of the WITT Wave Energy Converter to generate megawatts of offshore power at a competitive LCOE
Principal Investigator: Porter, Dr R
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Mathematics
Organisation: University of Bristol
Scheme: Technology Programme
Starts: 05 May 2015 Ends: 31 August 2016 Value (£): 85,602
EPSRC Research Topic Classifications:
Energy - Marine & Hydropower
EPSRC Industrial Sector Classifications:
Energy
Related Grants:
EP/N508652/1
Panel History:  
Summary on Grant Application Form
The potential for harnessing significant amounts of clean renewable energy from ocean waves is vast. Commitments made

by the UK government and others to tackle climate change require an expansion in development and deployment of

renewable technologies and it is widely recognised that ocean wave energy will play an important role in meeting future

targets for the reduction of carbon emissions. Whilst significant advances have been made over the last 35 years in

developing new ideas aimed towards producing robust and economically viable wave energy converters (WECs) there

remains no clear consensus on future direction of design and operation of WECs.

In addition to supporting existing concepts, it is important that promising new ideas for wave energy conversion continue to

be explored. It is widely accepted that there are two key elements to a successful WEC design. First, the design should be

driven by fundamental theoretical principles of wave energy absorption as these ultimately determine the capacity for

power conversion. Second, prospective designs must take account of the significant engineering challenges that arise

when operating in harsh marine environments.

In a recent paper "A submerged cylinder wave energy converter" Crowley, Porter & Evans, Journal of Fluid Mechanics,

2013, vol 716, (hereafter CPE) advocated a WEC design which sought to address these two demands. In particular, the

design was assumed to use an internal power take-off system consisting of a pendulum rotating on a horizontal axis whose rotation was damped to produce power. Such a design benefits by its isolation from the marine environment, mechanically

robust by relying on few moving parts and free from end-stop problems associated with over-excitation of the device. A

combination of theoretical and numerical results demonstrated that the device of CPE extracts significant power over a

broad range of energy-dense wave periods. Indeed, a mean capture factor more than double any existing WEC of its type

was predicted.

The WITT developed by WITT Limited under whom this TSB grant is being led is closely related to the device conceived in

the work of CPE. Instead of a linear device working in surge/pitch modes of motion enclosed within a long cylinder, the

WITT is a device designed for use in buoys. It not only converts power in surge and pitch modes but also in sway and roll.

The WITT has been developed by specialists in gear transmission systems and has been shown to have high efficiency in

conversion of kinetic to electric power. It is scalable and robust.

The project being led by WITT includes partners specialising in mooring systems and marine deployment, power take-off

design and manufacture and experimental methods including wave tank testing.

In Bristol, the project will develop a theoretical model for the operation of the WITT WEC device as a spherical buoy either

floating or submerged, to include effect of the mooring lines, the device and its interaction with a model sea state and the

internal power take-off system. The work will be based on the earlier work of CPE, with changes implementated to account

for the revised converter geometry, mooring line configuration and power take-off system. After verification tests have been

completed, an optimisation method will be applied to determine parameters for optimal power conversion for WITT devices

over a range of physical scales.

The work will develop in tandem with other partners on the project, in particular in developing the optimal mooring system

and through the validation of theoretical predictions by the experimental work performed in Southampton.

The successful completion of this project will result in a set of experimentally-validated theoretical results for a WEC design

with the potential to be developed a larger scale and eventually to full scale commercialisation.
Key Findings
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Project URL:  
Further Information:  
Organisation Website: http://www.bris.ac.uk