Up till now, we have mainly talked about wave power, osmotic power and ocean thermal energy power. All of them consist in obtaining energy from the sea, be it by the power of the waves, the difference of salinity between two masses of water or by the difference of temperature of sea lever water and deep water.
Today a new concept is going to be introduced: Tidal Power. It is based on the movement of the rise and fall of sea levels. These tides are produced by the gravitational forces that the moon and the sun produce on the sea. Most places usually experiment two high tides and two low tides a day, although there are places that only have one high tide and one low tide a day.
Tidal power is not widely used yet, but it has certainly got a great potential. On the one hand, the worst aspects are that the development is very expensive, and that like all marine power types, it cannot be take place anywhere. On the other hand, tides are a totally predictable phenomenon, therefore it makes it a totally reliable mean of energy. Bear in mind that the greater the tide differences are, or the stronger the currents are, more energy will be produced.
There are three main methods to generate power from tides, some of which will be studied in following posts: Tidal Barrages, Tidal Stream Generators and Dynamic Tidal Power.
Tidal Barrages make use of the potential energy of the tides. They are situated in river estuaries, and as the tide flows in and out, it generates power. But don’t be mistaken, it is not a dam, because it does lets the water flow in and out although it is not very nature friendly either.
Tidal Stream Generators are the classic machines that one thinks of when it is being talked about tidal power. They are like wind power generators, but placed under the sea. These generators take benefit of the kinetic energy of the water flows that tides generate to move an axis centered rotor. This is the cheapest way of generating energy from tides, so as the most environmental friendly.
Dynamic Tidal Power. It is a new way of exploiting the sea’s potential to create energy. It still hasn’t taken place anywhere, and is still under research. It consists of a dam-like T form structure that comes 30 to 60 km out of the coastline. The idea is for it to interfere with coast parallel tidal flows, strong such as in China, Korea and the UK. It would generate up to 1GW, but what would happen to shipping routes, marine ecology, sediments and so on?