The Annapolis Tidal Power Plant came online in 1984. The turbine is a single effect 7.6 m diameter horizontal axis Straflow turbine designed to generate power during discharge from the reservoir into the sea. It has a capacity of 20 megawatts and a daily output of roughly 80-100 megawatt hours, depending on the tides.
Located in the Bay of Fundy and Annapolis River, near Granville’s Ferry and Annapolis Royal, Canada.
The Annapolis Tidal Generating Station generates electricity from tidal flows in the Bay of Fundy, and operates in full compliance with all regulatory requirements (i.e. Fisheries Act). Although Annapolis Tidal maintains operating agreements with DFO, no formal Operating Approval exists for Annapolis Tidal with Nova Scotia Environment (NSE), as the facility operates in federal jurisdiction solely.
In 1980 Nova Scotia Power started construction on Hogg Island at the mouth of the Annapolis River as a federal and provincial government pilot project. Four years later the construction was complete and the station began operation. It is currently the third largest tidal barrage in the world.
Due to equipment failure, the plant was shut down in January 2019 and the project was subsequently cancelled.
Key Environmental Issues
EIA included release of suspended sediment, scour in existing channels and at adjacent shorelines, flood flow management, and passage of anadromous fish through the barrage. Concerns with increased basin water levels included interference with existing agriculture, flooding, and accelerated rates of bank erosion.
While effectively generating electricity, the blocking of water flow by the dam (to allow the tidal difference to accumulate every six hours) has caused a slight increase in river bank erosion on both the upstream and downstream ends. The dam also has the potential to trap some marine life. Two notable cases occurred in:
- August 2004: a mature Humpback whale (nicknamed Sluice) swam through the open sluice gate at slack tide, ending up trapped for several days in the upper part of the river before eventually finding its way out to the Annapolis Basin.
- Spring 2007: When a body of an immature Humpback whale was discovered near the head of tide in the river at Bridgetown. A post-mortem was inconclusive but suggested the whale had become trapped in the river after following fish through the sluice gates.
Post-Installation Monitoring: Annapolis Tidal Station
|Stressor||Receptor||Study Description||Design and Methods||Results||Status|
|Marine Mammals||Marine Mammal Observation||NA||August 2004: a mature Humpback whale (nicknamed Sluice) swam through the open sluice gate at slack tide, ending up trapped for several days in the upper part of the river before eventually finding its way out to the Annapolis Basin. Spring 2007: When a body of an immature Humpback whale was discovered near the head of tide in the river at Bridgetown. A post-mortem was inconclusive but suggested the whale had become trapped in the river after following fish through the sluice gates. ||Completed|
|Collision||Fish||Passage of anadromous fish through the barrage.||NA||The study was hampered by the fact that almost no quantitative data on fish movement in the vicinity of the barrage or the levels of mortality associated with passage through large diameter straight flow turbines were available. ||Completed|
|Changes in Flow||Physical Environment||Release of suspended sediment, scour in existing channels and at adjacent shorelines, flood flow management.||Numerical plume dispersion models were constructed to predict the decay of the velocity fields created by the discharges. ||The data indicated that while the velocities decayed very rapidly, the discharges from the turbine would impinge upon 430 m of downstream shoreline at velocities up to 0.5 m/sec while, in the basin, the velocities would be as high as 0.9 m/sec but the length affected would be only 160 m. Discharges from the sluice gates would not impinge on any |
shorelines, but velocities of 0.1 m/sec from these flows would still be
experienced 2.6 km upstream. Calculations showed that the velocities at the shorelines would only be about one-half those experienced with spring tides before the barrage was constructed, and that significant erosion was unlikely to occur. A layer of natural cobble on both shores will prevent serious bank undercutting. The only material that will be scoured by any of these discharges is a thin layer (<0.5 m) of sediment that has accumulated in the basin since barrage construction.