Tidal energy is that which comes from the movement of the tides. Two types of tidal energy can be obtained: kinetic energy from ocean currents and potential energy from the height difference between high and low tides. For it to be converted into electricity, it is necessary to build dams, locks and power generating units.
Although it is a renewable and clean source of energy and can replace the use of fossil fuels , tidal energy is still underused. This is because, to be efficient and economically viable, the coast needs to have specific characteristics, such as tides greater than three meters. In addition, its final price is high, making tidal energy unattractive compared to other sources.
Emergence of ecological energies
The First Industrial Revolution, in addition to generating transformations related to the work and production process, increased consumption and dependence on different energy sources for the most varied human activities. Initially, coal – both vegetable and mineral – was the main energy source used in the world. Later, other sources began to compose the planet’s energy matrix, such as oil , electricity and biomass .
Petroleum, mineral coal and natural gas , also called fossil fuels due to their formation resulting from the sedimentation and decomposition of organic matter, correspond to the main energy sources used in the world, representing 80% of the global energy matrix.
The world’s high dependence on fossil fuels brings several challenges for the future. Firstly, they are finite energy sources, since their production cycle involves long geological ages. In addition, they are sources that produce greenhouse gases such as CO2 , which aggravate climate change and its future consequences.
These challenges have resulted in a greater demand for cleaner energy sources. Several countries, such as Germany, Sweden, the United Kingdom and even nations known for their high levels of pollutant emissions, such as China and the United States, have increased their investments in the search for alternative sources of energy.
Standing out as alternative and renewable sources are hydroelectric , tidal , geothermal , solar and wind , of which the last two are the ones with the greatest growth potential, according to current forecasts.
Power generation system
The electricity generation system is analogous to that of a hydroelectric plant . The dams are built close to the sea, and the dykes act to capture water during high tide. The water is stored and later released during low tide, passing through a turbine that generates electricity.
The power of the tides has been used since the 11th century, when the French and English used this resource to move small mills. However, the first major project to generate electricity from the tides was carried out in 1967. In that year, the French built a 710-metre dam on the River Rance, taking advantage of the tidal energy potential.
Advantages and disadvantages of tidal energy
As previously mentioned, tidal energy can be an alternative to the use of fossil fuels, as it is a renewable and clean source of energy. However, it is worth noting that few locations have characteristics conducive to obtaining this type of energy. Other aggravating factors are high investments and low energy use.
In addition, a negative impact of the implementation of large projects is the change in the way of life of the populations that live in the region, or in the surroundings of the place where the plant will be implanted. It is important to point out that these communities are often human groups identified as traditional populations (indigenous peoples, quilombolas, Amazon riverside communities and others), whose survival depends on the use of resources from the place where they live, and which have links with the territory of cultural order.
Furthermore, rivers tend to have a dynamic balance between discharge, average water velocity, sediment load and bed morphology. The construction of reservoirs affects this balance and, consequently, causes hydrological and sedimentary changes, not only at the damming site, but also in the surrounding area and in the bed below the dam.
Main locations of Tidal Energy
The places that have great potential for tidal energy production are the Bay of Fundy, in Canada, and the Mont-Saint-Michel bay, in France, which have about 15 meters of difference in level between high and low tide. In Brazil, one can mention the estuary of the Bacanga River, in São Luís, and the island of Macapá, in Amapá, with differences in level of approximately seven and 11 meters, respectively.