Abstract
The Bristol Channel/Severn Estuary has some of the largest tides in the world with a mean spring tidal range of 12.2 m. Numerous proposals have been made to exploit this for energy extraction. However, the large tidal range is partially driven by tidal resonance and such systems can be sensitive to small changes. Thus, it is important to understand the impact of a barrage on the resonance of the system which in turn leads to an understanding of the environmental impact of building a barrage. In this paper, we examine the resonant response of the Bristol Channel system, with and without a barrage structure deployed, using a depth-averaged numerical model. We find that the barrage can alter the response of the Bristol Channel to excitation with higher frequencies than 12 h. However, the barrage causes very little change to the resonant response for longer periods including for the semi-diurnal periods which dominate the tides in the region. We also briefly examine the Swansea Lagoon scheme and find that this is too small to have a significant impact on the resonant response of the channel.
Highlights
Tidal energy is a clean and predictable, intermittent source of power
A key part of the decision making process as to whether to go ahead with such schemes is to appreciate the effect they would have on the tidal hydrodynamics
The study we present here looks explicitly at the resonance phenomenon and how this is modified by the presence of a Severn Barrage
Summary
Tidal energy is a clean and predictable, intermittent source of power. Tidal barrages or lagoons enable a head difference to be built up across tidal turbines as the tide goes in and out. A more recent proposal has been made for a smaller scale tidal ‘lagoon’ in Swansea Bay (Waters and Aggidis 2016). This would be primarily a proof of concept project. A key part of the decision making process as to whether to go ahead with such schemes is to appreciate the effect they would have on the tidal hydrodynamics. This is important both in assessing the power output and in determining the environmental change caused by such a structure. This paper focuses on understanding some of the fundamental science of how the hydrodynamics are modified
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