Sunday, October 28, 2012

Energy Generation: Stingray Tidal Power & Frond Wave Power

The Engineering Business (EB) started investigating renewables as a potential third market, behind submarine telecom and offshore oil and gas, in 1997 and comments that it soon became clear that Renewable Offshore Power Generation would be the most attractive technology area given the experience and expertise of EB staff. The devices currently being developed include both tidal and wave energy technologies, dominated by the 'Stingray' tidal generator and the 'EB Frond' wave energy converter.

Stingray uses the flow of the tidal stream over a hydroplane to create an oscillating motion that operates hydraulic cylinders to drive a motor that, in turn, drives an electrical generator. This device is a seabed mounted machine, to be situated typically in any water depth up to 100m.

The EB Frond, on the other hand, is a seabed mounted nearshore wave energy device designed for installation in 20-35 metres of water. A paddle-like collector on the end of a long lever is placed close to the sea surface and driven by the waves to produce hydraulic power similar to that of the Stingray.

In September 2002 EB tested the Stingray generator offshore in the Yell Sound off the Shetland Islands in the Highlands. The 180 tonne, 150 kW machine was installed and removed safely and data collected for analysis to aid the further development of both the demonstrator and commercial units. The 3rd phase of the development programme, a reinstallation of the demonstrator in the Yell Sound, has also been completed in 2003 and included a more flexible control system to allow the performance of the generator to be accurately controlled and recorded over a longer period.

The EB Frond is not at such an advanced stage of development but the phase 1 physical testing has been undertaken at scales of 1/33rd and 1/25th in the Lancaster University test tank, the academic partners in the project. Phase 2 is proposed for development in which a larger model will be deployed in more varied and extreme wave conditions. EB state that if this is successful it should lead to the design, build and installation of a full-scale demonstrator in a real near-shore wave environment, possibly as early as this year.

Future plans for the Stingray include a 5MW pre-commercial Stingray farm to be connected to a local power distribution system in order to test an innovative system for smoothing the flow of electricity from the oscillating devices.

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The megawatt (symbol: MW) is a unit for measuring power equal to one million watts. Or enough to electricity to power 50 thousand x 20 watt low energy light bulbs.

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