Tidal turbine

A UK-developed vertical axis turbine that can generate power from tidal movements has successfully completed the current phase of its evaluation trials.



Developed in the UK by Cornwall-based FreeFlow 69, the Osprey turbine is designed to generate power from tidal movements of the sea, rivers and inland waterways.



Following positive initial testing of a reduced-scale model in 2007, a full-size prototype has recently been trialled with what has been described as ‘significant success’.



A purpose-designed, 30ft-long aluminium catamaran rig was designed and built by associate company, Able Engineering of Swadlincote, Derbyshire, for use in these trials.



The test rig is equipped with a hydraulic scissor lift, to lower and retract the turbine housing into the water flow, and is powered by two outboard engines.



The rig drives the turbines through still water to simulate a current or flow of water at different speeds and it incorporates calibrated instrumentation to determine the power output of the turbine, together with two systems for measuring the torque loading on the contra-rotating blades.



Pat Cooke of FreeFlow 69 said: ‘Viability of the Osprey turbine concept has now been further proven. It has performed exceptionally well in the latest trials, with power output on target with our expectations.



‘The Carbon Trust has estimated that wave and tidal power could provide a fifth of the UK’s electricity needs. And, while we are confident that the Osprey turbine could significantly aid the UK in achieving its renewable energy targets, we definitely see huge potential for the Osprey worldwide.’



Osprey can reportedly provide power independently or as part of a larger system and outputs from 1kW up to 5MW in a multiple system are anticipated.



The Osprey turbine has also been designed as a key component of a conceptual modular lagoon-type hybrid generating system, harvesting power from tidal rise and fall, tidal flow boosted by a venturi and wind turbines.



According to FreeFlow 69, this system could be an alternative solution to the Severn barrage, or could be included as part of it, and is a simpler development of FreeFlow 69’s original Ocean Hydro Electricity Generator concept.



With the significant benefit of the gearbox and generator being above the water level, the Osprey turbine can operate effectively in variable depths to maximise power efficiency throughout the tidal cycle or in differing river heights.



It is also environmentally friendly, will not interfere with marine or river life and can be mounted on the seabed or suspended on pontoons.



With its bi-directional operation it will turn the same way in a flooding or ebbing tide and its modular design enables a bank of Osprey turbines to be built up and added to in order to generate more power.



FreeFlow 69 is now actively seeking a suitable sponsor to assist with funding for the next phase of development, which will include independent validation of the Osprey turbine’s performance and power-generation potential.