SIMPLIFIED TIDAL BARRAGE FOR SMALL-SCALE APPLICATIONS

The performance of a tidal barrage with no gates and continuous flow t hrough its turbines has been investigated by simulation. Double-effect generation could be achieved with an axial-dow turbine that reverses direction after each half of the tidal cycle. Such a system might be a ttractive for unmanned operation in remote areas, perhaps on a smaller scale than for conventional barrage systems. Predictions have been ma de about the energy obtainable from such a system, and the conditions necessary to maximize energy capture have been determined. A mathemati cal model of a high specific speed turbine, incorporated into the pred iction procedures, allowed the behavior of the system under varying ti dal range (and hence varying head) to be examined. Differential heads across the turbine are somewhat less than those achievable with a gate d barrage, and performance is correspondingly affected in very small t idal ranges. Variable-speed turbine operation was found to be benefici al in these circumstances. Overall levels of predicted output were ver y encouraging and compare surprisingly well with conventional barrage schemes. The concept would seem to merit further investigation.