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A small team of engineers based in Cornwall, England, have made a breakthrough with the development of a turbine that they claim could solve the commercial viability of tidal power. Known as the Osprey turbine, the technology can be used to create electricity offshore at sea -- or in tidal rivers and inland waterways.
"If this is successful, as we are confident it will be, we intend to manufacture a range of small units for river applications, followed by a range of cross flow turbines for conventional micro hydro plants."
Pat Cooke, Able Engineering & FreeFlow 69
The Osprey turbine is a vertical axis free flow device which produces power independently or as part of a larger system. Power output is expected to be from 1 kW up to 5 MW in a multiple system. It is the brainchild of Fowey-based FreeFlow 69 Ltd., research and development consultants in renewable energy, which is headed up by Pat Cooke.
The team conceived the unique turbine concept while working on design and development for their offshore Ocean Hydro Electricity Generator (OHEG), a concept using tidal energy to create electricity 24 hours a day. Following successful testing of a model rotor, a reduced-scale model prototype has been developed to assist in the design of a full-scale prototype.
"There is still some way to go before the Osprey is fully commissioned and starts to generate electricity for the national grid," said Cooke. "But if, as we envisage it will, the Osprey performs successfully, it could play a key role in providing a simple 24-7 green power system—possibly in conjunction with a simplified version of our original OHEG concept."
With the advantage of having the gearbox and generator above the water level, the technology operates effectively in variable depths to maximize the efficiency of the power available through the tidal cycle, or in differing river heights.
It is also environmentally friendly and will not interfere with marine or river life, can be mounted on the sea bed or suspended on pontoons, is bi-directional and will turn the same way in a flooding or ebbing tide. Due to its modular design, a bank of Osprey turbines can be built up and added to in order to generate more power.
"We already have a patent application in place and plan to build a full size prototype by the Autumn," said Cooke. "If this is successful, as we are confident it will be, we intend to manufacture a range of small units for river applications, followed by a range of cross flow turbines for conventional micro hydro plants."
A prototype for an Archimedes screw type version turbine will also be produced for rivers where a weir or leat is available, such as old mill sites. Able Engineering will manufacture the river turbines and take on the project management of the larger river systems, while FreeFlow 69 will act as developer for the larger offshore systems.
Cooke, who is Chairman of Able Engineering as well as leading the FreeFlow 69 team, believes that exploiting tidal power from the sea and rivers can play a significant role in achieving the UK government's targets for renewable energy.
"It is estimated by the Carbon Trust that wave and tidal power can provide a fifth of the UK's electricity needs," he said. "The benefits of ramping up investment in tidal power generation would be considerable, providing not only a reliable source of energy, but the opportunity for Britain to be at the forefront of the global market in the same way that Danish companies took an early lead in the wind turbine industry."
The idea reminds me of a test we had by our hydraulics professor at the university:
1. A submarine is moving under water, its mass is M, and the total drag is D.
2. A propeller on a mast protrudes above the water holding a turbine turning at w rpm, with blade diameter d and other physical characteristics as indicated.
3. A turbine type water pump is fixed to the submarine, with impeller diameter d1 and turning at w1 rpm.
Calculate the speed of the submarine.
Keep It Simple Son. Did you consider ... Varying sea level, varying wave heights, storms, construction costs, operation and maintenance costs???.
Visit www.renewableenergypumps.com Funny no body from Access commented.
Shamil Ayntrazi, PE
This seems to be too much infrastructure for a low ROI. Very little quantatative data is presented just some wild estimates of satisfying 20% of the UK energy. More focus should be directed to wave energy systems such as CETO where there is a real proven energy available 24x7 that could supply 100% of the required energy and make desalinated water as well. The wave equipment is below the surface and uses well proven technology components from the undersea drilling industry with the generation components on shore.
See: http://www.reh-plc.com/projects_background.asp
It's time to get beyond pipe dreams and start really doing something!
Does anyone know whether an array of these systems extract enough energy to significantly reduce wave action on the shore?
And, if so, would they provide the additional benefit of acting a bit like a sea wall? If so, that could significantly defray the cost in locations where sea walls are desirable and would be built at a specific cost, even without any power generation benefits.
I share Scott's imagination. For the past couple of years I have conceived of the possibility of an array of vanes, with some kind of turbine collector methodology, that could also function as a sea wall that could reduce costal damage and erosion in the face of our increasingly volatile weather systems.
I don't mind the complexity of the triple harvesting approach but a Keep It Simple Stupid (KISS) strategy does strike me as a less obtrusive way to go.
Shamil, I am trying to get a better sense of what you are getting at, not being an engineer, trained or untrained. I would hope that we have enough collective experience with fluid and hydro dynamics to address your several concerns.
I probably haven't been paying close enough attention but aren't there tidal harvesting arrays off of the coasts of Scotaland and Denmark? What kinds of technologies are they deploying?
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