Correcting the Under-estimate of the Tidal-Stream Resource of the Pentland Firth

The equation used for predicting the output of a wind turbine in an open flow field uses the cube of wind velocity. But the correct equation for an hydraulic machine in a closed duct uses the first power of flow rate times the pressure head. This paper argues that the second equation should be used for close-packed tidal- stream turbines in long channels where the water has no easy escape path and that it will lead to a much larger estimate for the size of the resource. It seems wrong to base the design of tidal steam plant on a fundamental misunderstanding of the energy source.