Water Current Turbines for River Applications - Alaska Energy ...

WCT Evaluation3.3.4 Hydraulically Tapped Duct SystemsNRCan-06-01071Rochester Venturi - HYDROVENTURI (UK, USA)Technology: The Rochester Venturi exploits two simple well known phenomena—it is difficult tocompress water, and, liquid or gas passing over a curved surface will generate a vacuum on the trailingedge of that surface. These phenomena are described by the Bernoulli Effect. HydroVenturi uses atechnology based on these simple principles to accelerate water through a choke system (see figurebelow). The acceleration creates a pressure drop in the device. This pressure drop is used to driveturbines. Using coupling devices, the turbines can be situated above water or even on shore. Thisremoves the need for complex moving parts or electrical parts in the water. There are three mainadvantages of this method of extracting energy: 1) The absence of moving mechanical or electricalcomponents in the water implies minimal maintenance costs; 2) The HV systems could be submerged sothat there are no visual impacts and shipping would not be impeded; and 3) The suction output fromseveral venturis could be connected in parallel to the same generator, providing economy of scale. Anunderwater barrage, honeycombed with venturis, can consist of a string of concrete caissons sunkroughly in a line. These could be re-floated for maintenance or for moving to another site, by pumpingout the water used to flood them when they were sunk. RV’s are modular and can be used to createsystems from 50kW to 500MW which have a 20% water to wire efficiency.Application: The system is designed to operate in tidal, ocean, and river currents.Stage of Development: HydroVenturi has spent the past 3 years developing and improving theirsystems by 1) extensive testing in our installation in the North of England, and more recently theircurrent design near Derby. 2) development of new and improved technologies in the primary system andin the power take-off and control electronics, 3) development of novel applications in our technology forlow head hydro and tidal sites, 4) in-depth feasibility studies of a range of locations, for example inScotland, Canada, New York, Iceland and New Zealand. Since 2005, HydroVenturi has beendeveloping an ultra-low head hydropower demonstrator site in the English Midlands.Verdant Power Canada ULC 31