The problem of ocean energy

Energy resources of the oceans are associated not only with hydrocarbon extracted in large quantities on the shelf, but with renewable energy sources. While ocean energy only to a very small extent, put at the service of man, which makes the problem a global sound (see also "energy problem").
Given the fact that the energy of the tides (tidal energy potential of the world's oceans is estimated at several billion kilowatts) in 2000 times the annual amount of energy of all the rivers of the world, this trend in global energy development is especially promising.
Unfortunately, the same can not be said of the other directions. Thus, a constant renewable resource is the kinetic energy of waves. Of course, it is located far from uniform in the waters of the ocean, but in some places on the shelf, where it is possible hydro, it reaches high concentrations. The first industrial wave power low power already built in Norway, Japan, and India. Most often with the help of the energy of the waves are driven generators installed on floating lighthouses. Despite the high cost costs, feasibility of establishing a wave stations is determined by specific geographical conditions, the presence or absence of alternative sources of incoming energy density, and so on. D.
Another direction in the development of the Ocean Energy has the potential to be the construction of power plants that use energy flows. The results of hydrological studies suggest that only the Gulf Stream in the most powerful of its parts (38 ° s. Lat.) Suffers every second of 82 million m3 of water, and during the year - 250 thousand. Km3, which is 6.5 times more than the annual runoff from all the land surface. Of course, installation projects in the interior of the Gulf Stream turbines large diameter for power generation today seem unreal, but it is possible that as the exacerbation of the energy situation in the world such projects have come back. The main limiting factors are the wide use of energy flows today - extremely low efficiency of the existing converters of this type of energy (of 0.5-10%), the colossal cost of giant turbines, many unresolved purely technical issues.
Direct relation to the problem of energy utilization has Ocean thermal energy waters. Solar heat is known to accumulate in the upper layers of the ocean, while the lower preserve fairly low temperatures. As a result, created significant differences in temperature of the surface and deep-lying water. In tropical latitudes on the surface of the water temperature reaches about 30 °, and a depth of 0.5 km - only 8-10 °. Thus, the amplitude of the temperature is approximately 20 °.
This phenomenon is the basis of the hydrothermal (or moretermalnyh) power plants. The principle of using the temperature difference is quite simple. It is known that with decreasing pressure lowers the boiling point of water and the temperature of the vapor, respectively. When heated by the water sucked in vacuum of 0.01 atm, it boils and forms steam that can rotate a turbine coupled to a generator. The function of cold water is to cool the vapor entering the condenser.
The idea of ??widespread use of the thermal energy is not new. Back in 1927, p. Meuse in France was built hydrothermal small power station. Then it was built a few larger (15 thousand. KW or more) stations in the United States, Japan, Cote d'Ivoire. In this new designs were developed hydrothermal stations, in particular based on the use of freon gas.
Finally, in a world created and discuss projects for the construction of power plants, based on the creation of an artificial drop of sea water in the narrow straits. However, the reality of such projects is very low.