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Scope Series 4 RTÉ Two, Thursday, 7.00pm

Marine Turbines

Marine Turbine 1Renewable energy company Marine Current Turbines (MCT) is proposing to install an experimental tidal turbine system in Strangford Lough in Northern Ireland this year.

This will be a research project involving a single monopile tidal turbine which will be installed for a period of between two and five years. It will then be removed.

Tidal turbine technology has been identified as one of the key renewable energy technologies which will help the UK achieve its CO2 emission reduction targets in the coming years.

It has an important role to play in meeting targets for averting global warming as well as a clean, sustainable replacement for fossil fuels in future. The UK government is financially supporting about half the cost of this project.

MCTis one of the World’s leading developers of tidal stream technology, and has successfully installed and operated a prototype experimental system near Lynmouth in North Devon for nearly two years.

Marine Turbine 2The proposed tidal turbine system comprises two turbines mounted either side of a single monopile structure.

Marine current turbines work, in principle, much like submerged windmills, but driven by flowing water rather than air.

They can be installed in the sea at places with high tidal current velocities, or in a few places with fast enough continuous ocean currents, to take out energy from these huge volumes of flowing water.

These flows have the major advantage of being an energy resource which is mostly as predictable as the tides that cause them, unlike wind or wave energy which respond to the more random quirks of the weather system.

The technology under development by MCT consists of twin axial flow rotors of 15m to 20m in diameter, each driving a generator via a gearbox, much like a hydro-electric turbine or a wind turbine. The twin power units of each system are mounted on wing-like extensions either side of a tubular steel monopile some 3m in diameter which is set into a hole drilled into the seabed.

The technology for placing monopiles at sea was developed by Seacore Ltd, a specialist offshore engineering company (and MCT's largest shareholder) which is co-operating with MCT in this work.

The submerged turbines, which will generally be rated at from 750 to 1500kW per unit (depending on the local flow pattern and peak velocity), will be grouped in arrays or farms under the sea, at places with high currents.

The turbines at Strangford Lough will generate approximately 1MW of electricity without causing any pollution, which approximately matches the energy requirements of Portaferry or Strangford villages


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