Capacity value of large tidal barrages

This paper presents for the first time a detailed capacity value calculation for tidal barrage generation, based on modelling of operational modes for the proposed 8 GW Severn Barrage scheme in Great Britain. The key finding is that the Effective Load Carrying Capability is very low as a percentage of installed capacity (less than 10% for the example presented here). This is because of the high probability of having zero available output at time of peak demand, if peak demand occurs on the wrong part of the tidal cycle; this result may be explained transparently using a simple two-state model of the barrage. The prospects for building a probabilistic model of tidal barrage availability are also discussed.