VATIS Update Non-conventional Energy . Oct-Dec 2015

Revision as of 06:47, 17 February 2016 by Kalpana Shibu (Talk | contribs)


New tidal energy system

Harnessing tidal power around the UK’s coast has so far been limited by the cost of the large dams and barrages required and unpredictable results. Now, Kepler Energy, the United Kingdom, in conjunction with researchers at Oxford University, the United Kingdomm has devised a way to overcome this obstacle by creating a new type of horizontal axis turbine that can be used underwater at depths of up to 30 meters, at an economical cost. Conventional propeller-type turbines are like underwater wind turbines and the number of suitable sites for them are vastly reduced by the size of their large blades, limiting their use to waters at least 30 meters deep.

The THAWT (Transverse Horizontal Axis Water Turbine) technology, by contrast, is designed for deployment in shallower, lower velocity, tidal waters. Put simply, as the water flows past the fence a head of water is produced that increases the turbine’s efficiency. The phenomenon is called a ‘blockage’ of the turbines and gets larger in proportion to the length of the fence. “The original Darrieus turbine has blades that are parallel to the axis of rotation, and that means that the loads in the blades are carried entirely by bending of the blades. That results in very high stresses. The re-design that we’ve done changes the blades so that they form this triangulated structure, and that’s a very stiff and very strong structural form,” said Guy Houlsby at Oxford.

The design has minimal moving parts in the water, while its generator and other electrical equipment are installed in dry columns, increasing their reliability, efficiency, and shelf life. The generating units consist of two sets of blades sitting on three columns with a single generator in between. The THAWT has a series of other advantages. It’s hardy, with each rotor having a 25 year design life and the columns and electricity connectors 100 years. It could also have positive knock-on effects for Britain’s carbon fiber manufacturing industry. THAWT’s electrical output would be equal to that of a nuclear power station, without any of the risk, and because the blades move at a relatively slow speed there is no danger to fish swimming through the fence.


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