Tidal power plant
When tidal power plants are discussed we always imagine a natural landform (river, estuary, cove, gulf, etc.) which has been closed by a great artificial barrier in order to contain and administer water and thus produce energy. The barrier impedes navigation, makes commercial exploitation of the area difficult and affects the environment and landscape on a grand scale.
Central tidal power plant on the Rance river in France
But it doesn´t have to be this way. There is a new system which, if it had been utilized in the fillings of the port facilities in the Vigo Estuary (Spain) for the last 40 years, would not have provoked any influence to the geography of the estuary and would have permitted the estuary to maintain the maritime and commercial capacity it has now. What´s more, it would produce electricity to the whole population of Vigo and its surroundings. If I say that in addition to that we would have an enormous volume of surface to cultivate different marine species, it would sound like a dream.Having read the above information you should, I suppose, already be interested in the project so I will explain now how the new system functions.The technique of the filling has always been used to obtain the necessary space for ports and maritime facilities. It consisted of throwing organic matter and the remains of different materials at the water’s edge. However some prefabricated concrete crates have been used recently for this purpose. They are made by floating dikes and are towed to their final location. The crates are then filled with sand or soil and finally covered with a concrete layer. Later on constructions, necessary for the commercial exploitation of the port, are elevated onto the concrete layer
Crate dike.- Transferred to its final location and being filled up with the sand from the sea bottom.
The 28 metres high extension crate of the Reina Sofia dock in Las Palmas. Filling of the crates in their final location.
The crates used to extend Gijon harbour. The extension works there were done in the open sea without any protection from the attacks of the Bay of Biscay waters. For this reason a strong protection dike had to be constructed first.
In the above sequence of photos you can see first the protection dike, the crates installed later, and the cross crates forming together the port surface, and finally a general view of the port extension.
If all port forming crates – the whole port surface which is about 100 hectares – were filled only to the minimum tide level (low tide) instead of filling them up to the top, sea water could enter freely into the crates. If the water enters through a hole or a canal and if a turbine generating electricity is installed in the entrance, we will have 2.000.000 cubic meters of sea water going in and out twice a day, taking into account that the difference between the levels of the medium annual tide is of 2 metres (there are tides of 4 metres and others that are hardly noticeable). This way we would have port facilities, a tidal power plant, and a marine farm of molluscs in the sand of the filling in the same place. We could also breed many other marine species if we lowered the level of the filling. ojThis way, as you can see, it would be a tidal power plant or a harbour of triple use.Naturally the construction units can be formed by one or more crates depending on the volume of water, the diameter of the canal of the generator, or the level of the tides (there are places on earth with tides of 12 or 14 metres).
If all port forming crates – the whole port surface which is about 100 hectares – were filled only to the minimum tide level (low tide) instead of filling them up to the top, sea water could enter freely into the crates. If the water enters through a hole or a canal and if a turbine generating electricity is installed in the entrance, we will have 2.000.000 cubic meters of sea water going in and out twice a day, taking into account that the difference between the levels of the medium annual tide is of 2 metres (there are tides of 4 metres and others that are hardly noticeable). This way we would have port facilities, a tidal power plant, and a marine farm of molluscs in the sand of the filling in the same place. We could also breed many other marine species if we lowered the level of the filling. ojThis way, as you can see, it would be a tidal power plant or a harbour of triple use.Naturally the construction units can be formed by one or more crates depending on the volume of water, the diameter of the canal of the generator, or the level of the tides (there are places on earth with tides of 12 or 14 metres).
I hope the following video will clarify what I try to explain.
According to Pedro Fernández Diez, the retired professor of the Technical School of Industry and Telecommunications Engineering at the Cantabria University and the author of many books on energy engineering, the potential energy of the tides in a place with an average amplitude of 3.5 metres over an area of 1 km2, that is 1,000,000 m2 is of 24 GWh per year.
Naturally this type of power plant would obtain a much greater result in such places as the Santa Cruz Province (Argentina) where the amplitude of the tides is 14 metres, the bay of Fundy in Canada with an amplitude of 15 metres, the Estuary of the River Severn in Great Britain with an amplitude of 13.6 metres or the Bristol Bay – 7 metres at the entrance and 12 metres towards the interior, etc.
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