Energy of ocean
Are some technical workings out of reception of energy from ocean though its contribution to power balance even is in the long term estimated is low.
Energy of inflow
The First possibility is use of energy of inflow. During inflow level of sea water raises, and these can take advantage for filling of any tank. On a water stream way it is possible to put the turbine which will develop the electric power. Return water stream during outflow also can rotate the turbine if its design provides possibility of direct and return rotation and development thus the electric power.
In the world experimental tidal power stations are maintained some. For us in the country at coast Barintseva of the sea since 1968 works Kislogubsky on which 2 turbines on 400 kw everyone are established. The big tidal station is maintained on the river La-Rans (France), its capacity - 240 thousand of kw. There are projects of a construction of other tidal stations. For example, in a mouth the rivers Severi (England), having the highest level of inflow on the Earth, are developed various variants of a construction of stations. Capacity of turbogenerators of this station made under the project of 7,2 million in kw. The governmental committee considering this project, recommended to spend studying of its possible influence on environment, definitions of its economic efficiency etc.
On similar with tidal a principle the power stations using energy of sea waves can work.
One of variants of wave power station is that: sea waves periodically compress air which is of inside vertically located chamber. Leaving the chamber, air actuates turbine blades. Falling, the wave creates vacuum therefore air which continues to rotate the turbine is from the outside sucked in in the cylinder. The main difficulty consisted in providing turbine rotation in the same direction at a direct and return current of air.
In other design the tank placed above sea level and connected by the inclined channel with its surface is used. At excitement sea water fills the tank, following from it, it rotates the turbine. Such wave power station of small capacity has been put in operation in Norway in 1985 Considering wave energy as one of possible power resources, it is necessary to specify in its considerable non-uniformity connected with change of intensity of an air stream over a surface of sea waters.
Nevertheless the available way of operation of wave power stations of small capacity testifies to utility of their application. Now in a number of foreign countries search works on studying of possibility of use of thermal energy of ocean are conducted. By results of this studying it will be possible to judge all merits and demerits of this kind of a power resource.
Energy of waves
World's reserves of wave energy make about 2,7 billion in kw. The problem consists in finding effective at cost ways of transformation of energy of moving waves in the mechanical or pneumatic form which can be used for a drive in action of turbogenerators. As at sea waves a wide range of lengths and amplitudes, any effective device or should be broadband, or have frequency adjustment. Here the technical problem is somewhat similar to a problem of use of wind energy.
Interest to a problem of use of energy of waves was especially showed last 10-15 years. Wide-ranging studies with "a practical exit" creations of installations not only skilled, but also for daily practice are spent, for example in Japan. Here on energy of sea waves operate over 300 buoys and beacons. In England also there is begun the corresponding program. At the Edinburgh university the special laboratory with skilled pool for imitations different kinds of sea excitement - from an easy ripple to 10-balls a storm, research and the control over a course of processes is created. Similar works and in Russia are conducted. What principle of action of wave power stations? What possible technical decisions?
1. Use of vertical liftings and recessions of a wave for at water in action of the water or air turbines connected with electro by generators.
2. Use of horizontal moving of waves by means of devices flugers type for reception through special transfer of a rotary motion.
3. Concentration of waves in the converging channel in which their kinetic energy would support a water pressure, sufficient for a drive in turbine action.
One of devices of the first group represents the vertical pipe shipped by the bottom open end in quiet enough layers of the sea and closed from above. The pipe is fixed on a float. In its top part, in "the wave" chamber, water has a free surface '. At lifting of a wave level of a free surface in "the wave" chamber rises and compresses air which puts in action the air turbine connected to the electrogenerator. At wave recession through the atmospheric valve in "the wave" chamber the new portion of air is sucked in. And further process repeats. The period of fluctuations of a water level - 5-6 with.
Thermal energy of ocean
Idea of reception of energy at the expense of a difference of water temperatures in superficial and ocean deep layers has been stated by scientists about 100 years ago.
But wide practical researches in this direction are developed only after 1973 Basic possibility of creation of industrial electric power plants on the basis of use of a temperature gradient of ocean water is confirmed. Experimental installations work on the Hawaiian Islands where the difference of temperatures at a water surface and on depth about kilometre makes 22 °С. Installation consists of the condenser, the evaporator, the pump and the turbine, working in the closed cycle. On pipes connecting them the working body - freon proceeds. The condenser is cooled by the water lifted from a deep water at temperature +8°С. The evaporator is at temperature of superficial water + 30 degrees. Passed in the evaporator in a gaseous state freon results the turbine then it is cooled in the condenser in rotation and again moves on heating in the evaporator.
Floating hydrothermal power stations can settle down there where temperature conditions in thickness of water optimum and give the highest gradient, including in the international waters on immense open spaces of the seas and oceans. Moreover, such power stations can be migrating, i.e. they are not adhered to any strictly certain area, and at change of temperature conditions can move there, where a gradient of temperatures the greatest and accordingly efficiency of their work the highest.
The modern technics allows to define the most perspective in this plan areas by means of companions of the Earth. But here, naturally, there is a problem: how to be with the developed electric power? Possibility of transportation of the electric power on coast on transmission lines - to underwater cables - behind range of distance, naturally, is excluded. In due course ways of transfer of the electric power on a long distance without wires will be, of course, fulfilled. For now the conclusion arises: electric power consumers should be here, on a place, i.e. be constructed not simply power stations, and electro-technologyes the complexes making on the basis of the developed electric power various kinds of secondary production.
The experts who are engaged in projects of use of thermal energy of ocean, consider that similar installations have considerable advantages in front of other devices realising energy renewed of sources - a wind, the sun or sea waves. The main thing from them - a constancy of a temperature gradient in time and, the inspector but, its reliability. A critical temperature difference at which ocean power stations become profitable, 22 degrees. In the World ocean it is a lot of such places. One more argument - low current expenses for the account of "free fuel". They make from 0,02 to 0,08 dollars for 1 kw-h.
Large ocean power stations capacity 200-400 Mvt mounted on floating platforms, according to their designers, will find application as factories on mining operations from ocean. Small stations capacity 40-50 MVt will be useful to developing countries of a tropical belt as, besides the electric power, they are capable to freshen water. It is possible to receive hydrogen and oxygen from water.
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