R Vennell – Renewable Energy, December 2012
► Turbines in large tidal straits may exceed the Betz limit on efficiency as they fill the channel’s cross-section. ► The efficiency of turbines in shallow channels falls below the Betz limit as they fill the cross-section. ► Maximizing the power production of large farms is not the same as maximizing the conversion efficiency of the turbines. ► The power produced by each turbine decreases as rows are added to a farm. ► The fraction of total power lost by the flow which is lost to bottom friction deceases as a farm expands.