Abstract
The Bay of Fundy in eastern Canada is renowned for its high tides, which are among the world’s largest; and for this reason, the Bay of Fundy (BoF) has long been recognized as one of the world’s premier locations for deployment of tidal power generation systems. The large tides are a result of the near-resonant response of the BoF-GoM system to the M2 tidal forcing. The tidal barrage at Annapolis Royal has been operating successfully since 1984; however, because of hydrodynamic and environmental impacts upstream of this barrage, this type of tidal power development remains highly controversial. Tidal power lagoons are an alternative approach to tidal power conversion that attempts to achieve high efficiency while avoiding some of the environmental problems associated with tidal barrages. A typical tidal power lagoon consists of a large impoundment structure (a rubble-mound dyke or caisson) and a power-house containing sluices and conventional low-head hydroelectric generating equipment, situated a mile or more offshore in an area with shallow depths and high tides. While tidal power lagoons are believed to be technically feasible and efficient, their potential effects on the hydrodynamics of the BoF-GoM tidal system has not been investigated previously and remains unknown. The main objective of the study described in this report was to discover and assess the scale and character of the changes in tidal hydrodynamics that would be caused by tidal power lagoons operating in the upper part of the Bay.
A detailed two-dimensional hydrodynamic model, based on the TELEMAC modelling system, has been developed to simulate tidal flows in the Bay of Fundy and Gulf of Maine. The model has been well calibrated and validated against water level and velocity data. Twenty different versions of the model have been developed to simulate existing conditions and nineteen hypothetical scenarios with one or more tidal power lagoons operating in the upper Bay. Methods were developed to simulate, numerically, the flows through low-head turbines and sluices, and the storage and release of water from a lagoon impoundment. Tidal power lagoons, varying in size from 12 km2 up to 58 km2, have been simulated at six prospective sites, three sites in Minas Basin and three in Chignecto Bay. In one scenario, the effect of six lagoons working together, one at each site, was investigated. The changes in tidal hydrodynamics throughout the BoF and GoM due to the presence and operation of one or more tidal lagoons have been estimated by differencing results from simulations with lagoons and an equivalent simulation of existing conditions without lagoons. The sensitivities to changes in lagoon location, lagoon size, lagoon type, the number of lagoons and their location have all been investigated. Moreover, relationships that describe the trade-off between power generation from lagoons and the magnitude of the resulting hydrodynamic change have been developed for several major communities around the BoF and GoM.
The methods employed in the study and the results of these simulations are presented and discussed in this report. These results will help inform current and future policies concerning the development of the vast tidal energy resources in the Bay of Fundy.