U.K. company refines wave energy converter

Offshore Wave Energy Ltd. (OWEL) of the United Kingdom has begun a new phase of research into its Grampus wave energy converter, studying the geometric configuration of the device to optimize its performance.

In association with IT Power LTd., OWEL is promoting the Grampus device, which is to convert ocean wave energy into compressed air to drive a turbine and produce electricity. The Grampus unit consists of a tapered, horizontal duct floating on the ocean. As a wave enters the duct, air is trapped in the duct and is compressed between the wave and the stationary upper surface of the duct. This compressed air is taken from the duct through a valve and used to drive a conventional unidirectional turbine.

OWEL Director John Kemp said the technology is based on the premise that the horizontal motion of waves can be harnessed more effectively than vertical motion. OWEL says a single, large Grampus unit could provide a capacity of 12 MW. When the system is deployed in the ocean, it will feature several ducts connected to a large floating concrete platform, in water at least 40 meters deep.

OWEL’s research has been funded by a grant from the United Kingdom’s South West Regional Development Agency (SWRDA) and from contributions of shareholders.

In addition to studying internal geometric configuration of the device, the SWRDA-funded study is to investigate the unit’s structural loading and mooring requirements. The work will utilize computational fluid dynamics (CFD) modeling and a series of tank tests in a selected wave basin.

On completion, OWEL said it would have an optimized full-scale design and a more detailed understanding of its performance and cost characteristics.

To prove the concept, OWEL performed a feasibility study of a 1:100-scale model in a tank and completed mathematical modeling. The company then performed physical testing in a tank as well as CFD modeling on a computer of a 1:10-scale model.

The next step in development of the technology involves construction of a prototype to be deployed in the ocean. OWEL hopes to deploy a three-quarter-scale unit at the European Marine Energy Center (EMEC) in Scotland’s Orkney Islands. (HNN 8/7/08)

OWEL was formed in 2001 by Kemp, Sycamore Projects – Marine, IT Power Ltd., and Business Link Wessex. Other partners include the New and Renewable Energy Center.

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