Is Blue the New Green? The Power of Water


Traditionally, the power of water has been harnessed through hydroelectric dams to produce energy. Now, researchers and developers in North America and Europe are working to deploy underwater turbines and wave energy converters to generate clean, renewable energy.

Harnessing the power of water can be traced back to the 8th Century CE, where the first tide mill was found in Northern Ireland. During high tide, sea water would fill a collection pond through a one-way gate. During low tide the gate would close automatically. Once the tide reached a certain level, the stored water would be released to turn a water wheel, which was used to crush grain. These early tidal energy converters are similar to tidal barrages, which are still used to generate electricity.

Today, as in years gone by, energy from tides—the natural rise and fall of coastal waters—is used to create electricity or other forms of power. Sea currents are magnified by the gravitational fields of the earth, moon, and sun pulling the water over geographic features, such as headlands, inlets, and straits.

The Bay of Fundy (home to the highest tides in the world) in Canada, provides an excellent example of the abundant resource that can be used to generate power. In this 270 km ocean bay between the Canadian provinces of Nova Scotia and New Brunswick, the rise and fall of the tide can be as high as 16 m. Over the course of 12 hours, 160 billion tons of seawater flows in and out of the Bay of Fundy during one tidal cycle, more than four times the flow of all the world’s freshwater rivers over the same time period. The movement of the tides is a renewable and predictable source of power.

There are Three Key Ways to Generate Tidal Energy:

Tidal Streams: A turbine, similar to a wind turbine, is submerged directly in an area of significant tidal change, such as the Bay of Fundy or Pentland Firth in Scotland. Tidal stream generators draw energy from the currents in the same way wind turbines draw energy from air currents. The major benefit of tidal stream generators is that water is 800 times the density of air, meaning more energy can be extracted by a smaller turbine.

Tidal Barrages & Tidal Lagoons….

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