Based in London, Minestro is a tidal power company that has developed a power plant known as Deep Green that converts energy from tidal stream flows. The company has taken an interesting approach that uses a hydrodynamic wing to direct smoother water flows through the turbine.
The design of the turbine itself is unremarkable. The key to the whole system is the wing labeled as '1' in the diagram above, which is directly from the Minestro website. The wing makes the system capable of operating in low velocity currents that would be too slow for other systems. The entire system is actually tethered to the sea floor by the cable indicated as '4' in the diagram. This cable allows the whole unit to move as the wing is pushed by the tidal currents. The movement this creates causes the turbine to be pushed through the water at speeds well in excess of the 2.5 meters per second generally thought of as the minimum for tidal stream applications. In essence, the entire unit moves like a large underwater kite.
There are two drawbacks to this technology. First, the strains placed on the wing and cable are fairly substantial and because the unit has to be light enough to float, this means that the materials used in construction are rather exotic and expensive. The second problem is that the kite-like activity may pose a threat to marine wildlife and appears to disturb the surrounding environment more than stationary turbines.
The company is currently developing a 3 MW test array in Strangford Lough, Northern Ireland. The test array will be complete by 2015 and, if successful, will be enlarged to 10 MW through 2016. Environmental monitoring of this unique approach to tidal power is paramount in the pilot deployment.