The great Nikola Tesla many times in private conversations argued that people are surrounded by energy everywhere, they just need to be able to use it. Mankind has gone the easiest way, taking from the nature of the most saturated with calories substances and burning them. The efficiency of resource use turns out to be low, but few people think about it, although Mendeleev also pointed out the proportionality of the benefits from the burning of oil and banknotes. Nevertheless, from time to time the academic world remembers its past experience or comes up with something new. So there are fields of wind turbines with generators, solar panels, tidal and geothermal power plants, other sources of energy that use the natural forces that are being wasted almost completely wasted today.
Energy of natural forces
Wind, waves, lightning, hurricanes, tornadoes, volcanic eruptions are large-scale movements of the masses and energy of air, water, heat and static electricity. If we succeed in learning how to take away from nature at least part of its strength for the needs of our growing civilization, then for the future of mankind, you can be calm. Otherwise, with the increasing consumption of non-renewable resources, their depletion is inevitable. Someday coal, oil, gas, uranium, plutonium and other minerals will run out, and a planetary energy collapse will occur. One of the possible ways out of a prospective crisis is rightly considered tidal power. As is clear from their name, they consume the energy of huge masses of water flowing from one part of the World Ocean to another with a certain frequency.
What is tide
The fact that the sea level rises and falls from time to time, people have known for a long time. This phenomenon was faced by ancient sailors. Having once started their ships in a cozy lagoon and trying to get out of it again into the sea, they suddenly ran into a stranded, which had not recently existed. Legends about the spirits that moved the underwater reefs, rocks, beating about the stem by the wave of mermaids and other fascinating myths. Soon, stranded again somewhere disappeared, and the ships moved on. The discovery of astronomical patterns led to the realization of the mutual connection between the concept of water level and the lunar phases. All explained the law of the world. Water was attracted to the Moon at the moments of its approach to the Earth with a force inversely proportional to the square of the distance between space bodies. From the point of view of physics, tidal power stations should be called lunar. They use the energy of water movement, which in turn draws power from the only natural satellite of our planet. The sun, by the way, also contributes to this process, even though it is farther than the moon, but then the mass of the star is much larger.
Tidal Mills, British, and Pomors
Intuitively, humanity learned to apply tidal energy long before the discoveries of Newton's laws. There were no electric generators either. But on the other hand, mills worked with might and main, the millstones of which were spinning with wheels with blades lowered into the water where the waves of the sea were the most active. Usually, the place for the construction of similar objects of the food industry was chosen by the ancient mills in the bays with a narrow mouth. There the water streams spit unwise mechanisms especially effectively. It was tide - the direction of rotation is one, and at low tide - the other, the opposite, and the grain does not care how the millstones rotate, it is ground in any case. In essence, the tidal mills were the same windmills, they only worked not in the air, but in the water environment. These devices functioned on the British Isles as early as the 12th century, and their appearance in Russia on the White Sea is known from the chronicles of the 17th century. Perhaps the Pomors used the English experience when they saw these mills during their trade missions, but it is possible that they themselves thought of it, they were talented.
After the fundamental discoveries in the field of theoretical electrical engineering, the question of practical industrial production of new energy came up close. The steam engine, the axis of the hydraulic installation screw or any other mechanical source with torque could rotate the generator shaft.
The simplest solution was the dam, which, by analogy with a water mill, used the difference of the level potentials. In the 19th century, steam engines were also widely used, as were internal combustion engines. In 1913, the world's first experimental tidal power station was built. The principle of operation of this energy source is used today. The power of the generator, mounted in Dee Bay, near the port of Liverpool, was small, 635 watts, but it did not start.
In 1935, the Americans, who were keen on innovations, tried to build a more powerful aggregate of “gratuitous” energy, invested a fair amount in the project, but the idea turned into a collapse. The relief of the seabed was not sufficiently studied, the ground “floated”, and efforts to shut off the water area of Passamakvodi Bay (US East Coast) were in vain.
But experience is always useful, experiments, even unsuccessful ones, are useful. In the course of the work, the engineers determined the necessary and sufficient conditions under which tidal power plants can operate, in particular, the minimum level difference. He was four meters. Naturally, the more, the better, but if less, then it’s not worth starting a construction of a PES.
It is quite obvious that during ebb and flow, the direction of water flow through the turbine propeller will be different. Moreover, the intensity of rotation also varies depending on the level of the working fluid in the energy-accumulating basin. In the design of turbines, these features of the concept engineers had to take into account. The generator shaft stops completely at two dead points, limiting the duty cycle. Rotation begins only when a level difference occurs, it does not matter whether it is positive or negative, as all tidal power plants work. Pros and cons are side by side in any systems and machines invented by people, nothing is perfect. It is important to properly evaluate the advantages and disadvantages.
What are good for environmental PES?
The main advantage is that these stations do not need fuel, and therefore there are no combustion products.
The second plus is also very important. Whatever happens, and whatever cataclysms (earthquakes, tsunamis, volcanic eruptions, aircraft crash, bombing, terrorist attack, etc.), the worst thing that can happen is the destruction of the work unit and the generator with the substation. Other consequences, such as spills of fuel, radioactive coolant, and even something terrible can not be due to the absence of hazardous process agents.
The third positive side, which favorably tidal power from hydroelectric, for example, is the principle work that lead to respect for the fish wealth of the country. Part of the plankton, of course, dies with the passage of the intakes, but not more than one-tenth (for comparison: the passage of the blades of hydropower plants does not stand up from 83 to 99% of the aquatic microfauna, the main feed of fish).
Fourthly, ice conditions practically do not affect the work of the PES.
Fifth, the salinity of the water remains almost unchanged.
And the sixth ecological moment is that the inevitable structural disturbances of the bottom arising during construction are completely “healed” in two years with the full restoration of the hydrobiosphere’s vital activity.
The only tidal power plant in Russia and the French Rance TPS, using their examples, showed that the cost of energy extracted from water is the lowest. In addition, the productivity of enterprises is highly stable and does not depend on any political or macroeconomic shocks. The work of TEC is affected only by the movement of space bodies. The increase or decrease in load levels and energy consumption by consumers also does not violate the technological regulations of operation.
The construction technology, called floating, allows you to create power units not at the site of future stations, but at coastal docks, and only then tow tidal power plants to the desired area of the world's oceans. Thus, the installation process is greatly simplified.
The greatest amplitude of the sea level is observed in the bays in which natural semi-closed basins are formed by the coastal relief. Changing the direction of rotation of the turbine is technically implemented through a variable pitch of the blades, in other words, their rotation relative to the axis of rotation. As a rule, turbines have the ability to switch from the generator to the pump mode, depending on the situation and the phase of the technological cycle. The main disadvantage of uneven performance is leveled by a common integrated power grid, of which tidal power plants are a part. The pros and cons of this technology, when compared, still incline power engineers and environmentalists in favor of PES.
Why are few of them?
If everything is so wonderful, then why are the shores of all continents not saturated with these wonderful, environmentally friendly, harmless and harmless, but very useful facilities? Why mankind still smokes in the atmosphere with fuel oil, coal and other exhausts, risks new Chernobyls and Fukushima, ruins fish with turbine blades of hydroelectric power stations and slows down the movement of rivers, leading to environmental violations? Greenpeace members reasonably claim that the tides of power plants alone can meet the modern needs of the world's inhabitants together with enterprises five thousand times. In the world, however, they can be counted on the fingers.
High cost and benefits
The fact is that they are very expensive. Each TPP costs as much as 150% more than a hydroelectric station of the same capacity. The cost of ruined fish and environmental damage no one considers. You can have a different attitude to the organization Greenpeace and not all support its activities, but it is probably worth listening to its members. And some have already done this.
The share of energy currently given by all tidal power plants in the world is insignificant, but it tends to steady growth. Now there are a little more than a dozen of them, they have different capacities, and only the principle of operation unites them.
Here is a list of them with their characteristics, country and year of commissioning:
Five more operating Chinese stations were not included in the list due to low power.
At the same time, experts estimate the total potential of hydro-tidal power engineering to be one million megawatts, obtained without burning fossil fuels or nuclear reactions.
Kislogubskaya tidal power plant worked until the complete wear of the aggregate and in 1994, was subjected to conservation, but in the beginning of the third Millennium it was decided to reconstruct for the purpose of conducting experimental studies. The issue of alternative receiving huge amounts of energy the leadership of the Russian Federation pays serious attention, despite the high cost of construction of industrial units.
The only tidal power plant in Russia is only a base for technology development. There is a project to build the world's largest Penzhinsky energy center in the Sea of Okhotsk with a total capacity of 135 GW. It is supposed to be used to produce huge amounts of hydrogen, necessary for the production of synthetic fossil fuels that do not form harmful chemical compounds during combustion. This project requires serious investments, but promises to give an effect, the value of which today is even difficult to estimate.
The question of exactly when the Penzhinsk tidal power plant in Russia will be built remains open.