The tidal power is received because of the energy of waves.
There are two ways that tidal power plants (TPPs) can harness this energy. The first uses the same principle as conventional hydroelectric power plants: the receiving turbine is placed below the tidal level and the force of the falling water rotates the turbines connected to an electric generator. The other method uses the energy of water movement – the difference between the ‘high’ and ‘low’ water levels at high tide. This involves setting up a dam on the seabed, cutting off the bay from the sea and consisting of a series of windmills, whose spinning turbines are linked to electric generators that feed the generated current to coastal power stations. The system reverses the direction of the turbine blades as the water changes direction. In order to build a hydroelectric plant, the tidal range will need to be at least five meters.[1] Tidal range energy potential in the world is 450 TWh/year.[2] By comparison, for instance, small scale hydro power in 1995 produced 115 TWh/year, this figure will increase to 220 TWh in 2010.[3] It can be assumed that the tidal range energy can play a significant role in the further progress of human society.
Problems
- the cost of tidal power plants.
- energy pulsation due to tidal cycling over a half-month period.
Output: When combined in the same power system with high-capacity thermal power plants, the energy generated by the PES can be used to cover the peak loads of the power system, and HPPs in the same system with seasonally regulated reservoirs can compensate for the intra-month fluctuations in tidal energy.
The advantages of a CCPP are:
- Uses a renewable energy source;
- Operates steadily in power grids with a guaranteed constant monthly power output. (Power generation in PES is not dependent on the water availability of the year);
- does not pollute the atmosphere by harmful emissions unlike thermal power plants;
- does not lead to flooding of lands unlike hydroelectric power plants as there is no need to create water reservoirs;
- does not pose a potential risk of radioactive contamination, unlike nuclear power plants;
- easier to maintain and more durable than oceanic wave power plants;
-Capital investments for building PES are not higher than costs for HES due to tested floating construction method in Russia[5] and application of new technological “orthogonal” hydro unit
-Relatively cheap cost of produced electricity. (proven over 35 years at Rance – France).
Among the disadvantages of using PES are usually mentioned:
- the span of the mill blades of bottom-mounted PESs impedes navigation in the areas where the plants are located;
- possible damage to marine flora and fauna during the construction and operation of the PES, although this fact is actively researched and often disputed.
Environmental safety:
- The PES dams are biologically permeable, allowing fish to pass through the PES unhindered;
The environmental damage caused by PES is much lower than that of hydropower plants. Studies by the Polar Institute of Fisheries and Oceanology confirm that no dead or damaged fish have been found in the area of the pilot Kislogubská PES. In addition, about 5-10% of plankton, the main food base for fish, is killed during the operation of the PES, whereas 83-99% during the operation of the hydropower plant.
- Reduction of water salinity in HPP basin, which determines ecological condition of sea fauna and ice, is 0.05-0.07 %, i.e. practically insensible. In addition, hummocks and prerequisites for their formation disappear in the basin, and ice pressure on the structure is not observed.
- Bottom scour and sediment movement during construction of the FPU are fully stabilised within the first two years of operation. The floating construction method makes it possible to avoid erecting temporary construction bases and bridges at HPP sites, which contributes to environmental protection of the HPP area.
- The operation of the power plant prevents the emission of harmful gases, ash, radioactive and thermal waste.
The power plant does not endanger people and changes in the area of its operation are only local in nature.
There are no more than 10 tidal power plants in the world. The largest is France’s La Rance, with an installed capacity of 240 MW. The power plant is located at the mouth of the River Rance in the Brittany region and was built in 1966. It has a tidal range of 12 to 18 metres. It has 24 turbines that operate for an average of 2,200 hours a year. Today, there is a great deal of interest in the potential of the power plant. Norwegian companies, for example, are testing a new and revolutionary underwater technology, which makes it possible to exploit the differing tidal heights (from 3 to 20 metres) found in Norway’s coastal waterscape. Hammerfest Strøm commissioned a project in Hammerfest in 2003.[10] The constructed power plant is a bottom-mill system and supplies electricity to 15-20 homes in the immediate coastal area. The company plans to expand its output and supply electricity to the entire town of Hammerfest.
Another Norwegian company, Statkraft, is testing a concept based on a floating underwater metal anchor structure. Its four turbines, which have 22-metre diameter rotors, are powered by the tide. It will be placed off the coast of Kvalsundet for a trial period of two years. The design has a number of positive features: it is easy to maintain and can be transported to shore terminals as required. Throughout the trial period, the research station at Trumso will be measuring the impact of the structure on benthic fauna. Its ecological effect is expected to be biologically neutral, as it has no permanent impact on benthic flora and fauna.