Up to the scale of 100 array,the optimal distribution of tidal stream site over the NW European shelf seas was identical for the cases where the threshold M2 current amplitude was in the range 1.0-2.0 m/s, and anglesey. For larger exploitation(e.g. up to 1000 arrays), there is a higher concentration in the Irish Sea and Faroe Island,with some development at Flamborough Head in the North Sea.