Abstract
The Passamaquoddy–Cobscook Bay archipelago, located near the entrance to the Bay of Fundy where the mean tidal range is 5.7 m, has long been regarded a promising site for tidal-power development. Modern low-head turbines allow power extraction primarily from the kinetic energy of the tidal stream, rather than from the potential energy of an impounded basin, eliminating the need for expensive and elaborate systems of dams, locks and gates. Although the available power levels are much less in streaming applications, the resource may still be significant and accessible in areas with strong tidal flows, because the available power follows the cube of the current speed. The much lower costs per installed kilowatt and the relatively minor environmental impacts warrant a fresh look at the tidal-stream resource.
Circulation models indicate that the peak power resource in narrow straits such as Letete Passage and Lubec Narrows exceeds 10 kW/m2 of installed turbine aperture. In those locations an installation with the surface “footprint” of a typical aquaculture site could produce peak power levels of 1–2 MW under mean tide conditions, and perhaps twice that during spring tides, using modern turbines. Lower power levels are available in deeper, less restricted regions such as Western and Head Harbor Passages. Regions between islands and near headlands where flow speeds exceed about 2 m s−1 (about 4 knots) offer a modest tidal-power potential that could be tapped at relatively low cost and with minimal impact on the environment, fisheries and navigation.