Exploring Our Fluid Earth

Scientists have been looking to renewable sources of energy in order to decrease our reliance on fossil fuels. The burning of fossil fuels is a serious environmental concern because it releases a lot of carbon dioxide into the atmosphere, a greenhouse gas that contributes to global warming.

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SF Fig. 6.17. (A) Aerial view of the tidal barrage at La Rance Tidal Power Station, Brittany, France

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Image courtesy of Tswgb, Wikimedia Commons

SF Fig. 6.17. (B) SeaFlow tidal turbine raised out of the water for maintenance, Devon, United Kingdom

Image courtesy of Fundy, Wikimedia Commons

SF Fig. 6.17. (C) Tidal turbine before installation, Race Rocks, British Columbia, Canada

Image courtesy of Gflet, Wikimedia Commons

The rise and fall of water due to tides is a predictable and reliable phenomenon. This feature makes tidal cycling an attractive source of renewable energy. Other sources of renewable energy like wind and solar power are less dependable because they can be affected by the weather. Tidal power transforms the energy of tidal currents into electricity. The first tidal power stations were built in the 1960s as “barrages” or dam-like structures across coastal inlets with high tidal ranges (SF Fig. 6.17 A). These tidal barrages contain fan-like turbines that generate electricity when they are turned by moving water. Newer tidal power stations use individual turbines fully submerged beneath the water surface (SF Fig. 6.17 B and SF Fig. 6.17 C) to reduce environmental impacts and allow local boat traffic.

Newer tidal power generators are generally underwater, so equipment has less of a visual impact compared to wind turbines, which are often set on hills and are sometimes criticized for spoiling scenic landscapes. One of the disadvantages of tidal power is that it only generates electricity during ebb or flood tides and might miss the times of peak electrical demand in nearby communities.