The hydrokinetic power resource in a tidal estuary: The Kennebec River of the central Maine coast

Power levels available from the kinetic energy of tidal flows can be significant in coastal or estuarine regions with relatively modest tidal ranges. For example, the central Maine coast, where the mean semi-diurnal tidal range is about 3 m, includes several river estuaries with narrow interconnecting passages where tidal currents exceed 2 m s−1. A numerical circulation model applied to this region shows that the vigorous tidal flows lead to available power peaks exceeding 3 kW per square meter of turbine aperture in several sites during a spring tide. At one promising location, the peak power density is 6.5 kW/m2 near the surface and the energy capacity in a 500 m2 section under mean tidal conditions is about 2700 MWh per year, sufficient to meet the average consumption needs of about 150 homes connected to an electrical grid capable of accepting the tidal power pulses and blending them with traditional sources.