Author(s): Roger A. Falconer; Junqiang Xia; Binliang Lin
Keywords: Severn Barrage; Tidal power; Coastal flooding; Operating modes; Ebb generation; Two-way generation; Hydrodynamic modeling; Hydro-environment
Abstract: The Severn Estuary in the UK has a spring tidal range approaching 14 m, which is regarded as having one of the highest tidal ranges in the world. Various proposals have been made regarding over the years for the construction of a tidal power barrage across the estuary to enable tidal energy to be extracted. The barrage scheme originally proposed by the Severn Tidal Power Group would be the largest project for tidal power generation in the world if built, as proposed. Therefore, it is important to study the impact of different operating modes for this barrage on the tidal power output, hydrodynamic processes and hydro-environmental characteristics in the estuary. In this paper, an existing twodimensional hydrodynamic model, based on an unstructured triangular mesh, has been integrated with a new algorithm developed for the estimation of tidal power output, which can account for three barrage operating modes, including ebb generation, flood generation, and two-way generation. The developed dynamic model was then used to investigate the impact of different barrage operating modes on the tidal power output and the associated extent of flood inundation along the Severn Estuary. Predicted results indicate that the mode of flood generation would produce the least electrical energy and cause a larger reduction in the maximum water levels upstream of the barrage. Two-way generation would provide an improvement to these conditions, and produce an equivalent amount of electricity to that from ebb generation, with a low installed capacity and a small loss of intertidal zones. Therefore, the mode of ebb generation or two-way generation would appear to be a preferred option for power generation, because both would offer benefits of acceptable electrical energy and reduced flood risk. The latter scheme however would offer less hydro-environmental change to the estuary.