Tidal range is the vertical difference in sea level between high and low tide and uses technology similar to the production of hydropower with a dam or barrage to impound a large volume of water.
The difference between the tide height inside and outside the impounded area causes water to be discharged from one side to the other. This water is forced through turbines inside the structure, which creates energy.
Since tidal energy production is not influenced by weather conditions but only by well-known cycles of the moon, sun and earth, it is entirely predictable.
For generating power commercially there are only 50 sites in 5 regions around the world with a sufficiently high tidal range. Here are some examples:
- Bay of Fundy, Canada
- Bristol Channel and Cardiff Bay, UK
- Normandy, France
- Magellan Strait, Argentina & Chile
- Cook Inlet, Alaska, USA
- Penzhinskaya Bay, Kamtchatka, Russia
The MeyGen tidal array project in Scotland stands out among the few large-scale tidal power projects under development.