AIRLIFT ACTUATED BY A SUCTION PUMP DRIVEN BY WIND ENERGY OR BY SEA WAVE ENERGY Description Field of the invention The present invention relates to a plant for artificial upwelling or for forced downwelling, as well as a variant thereof for the production of compressed air by water compression, which uses an airlift pumping system supplied with air at atmospheric pressure, thanks to one or more suction pumps, actuated by wind energy or by sea wave energy or by both. State of the art With regard to artificial upwelling, the devices that have been invented to cause artificial upwelling are innumerable. Thus, thought has been given to the possibility of using differences in density, in temperature, in salinity between surface water and deep water, the oscillatory motion of waves, the energy of currents, hybrid systems that use solar, chemical, wind energy, etc. A fairly complete summary of the various technologies can be read in “Research progress in artificial upwelling and its potential environmental effects”, Pan Y., Fan W. et al., in Science China Earth Science, 2015; “Feasibility analysis and trial of air-lift artificial upwelling powered by hybrid energy system”, Yang J., Zhang D. et al., in Ocean Engineering, 2017, pages 520-528; as well as in “Artificial upwelling using offshore wind energy for mariculture applications”, Pelegrí J.L. and Vaqué D., Planet Ocean, Scientia Marina, September 2016, pages. 235-248; “Development of air-lifted artificial upwelling powered by wave”, Chen J. W., Yang J, et al., in MTS/IEEE Oceans Conference, Sep. 23-27, 2013. San Diego 1-7. Currently, the system deemed the most efficient is the one based on artificial upwelling with the airlift system. This system can be summarized as follows: an upwelling pipe is immersed vertically in water; the lower end is placed at the depth (as a rule, at least 300 meters) at which the water to be lifted is located; the upper end - which serves as a discharge outlet - is positioned at the height (or in proximity to) the sea surface. Into the upper segment of the pipe, at a depth of at least 5-10 meters, through a dedicated pipe with diffuser, is blown compressed air which, mixing with the water present in that segment of the pipe, reduces its density. Following this, a pressure drop is created between the column of the air-water mixture present inside the pipe and the corresponding column of water external thereto, as a consequence of which deep water starts to rise - and continues to do so throughout the time in which compressed air is blown - and flows out from the discharge outlet. The compressed air necessary for airlift operation is produced by a specific compressor, actuated electrically or powered by fossil fuels, installed, if possible, on the ground, or on barges, or floating platforms. It has also been thought possible to use piston compressors, connected to floating devices, actuated by wave energy. The limitation of this type of compressors is given, mainly, by the fact that the pumps operate through moving mechanical members and that the quantity of compressed air obtainable through the wave motion is tied to the dimensional characteristics of the pump, which are inevitably limited. Moreover, a mechanical pump that operates in a marine environment may easily be subject to phenomena of corrosion and wear and to frequent failures. Since the compressed air necessary for the operation of the airlift can also have compression value that is not very high, consideration has been given to the idea of injecting into the upper segment of the upwelling pipe the compressed air produced by an OWC connected thereto by means of a flexible tube. A system of this type - studied and proposed as early as 1976 by Mc Cornick - is well described by Liang, N.K. (see “A Preliminary Study on Air-lift ArtiÞcial Upwelling System”, Liang, N.K., 1996. Acta Oceanogr, Taiwan, pp. 187-200). The great advantage of this type of plant, with respect to those that use mechanical compressors, is, in the first place, that the piston used to compress air is a hydraulic piston, which allows to overcome all the disadvantages and critical issues encountered by any type of mechanical pump that has to operate immersed in a marine environment. Moreover, using a hydraulic piston allows to use OWCs of large size (with the sole limitation imposed by the characteristics of the wave motion recorded in the installation site) and hence to produce large volumes of compressed air. Given these advantages, however, there remains the severe limitation deriving from the fact that the plant comprises three distinct components (an OWC caisson, the upwelling pipe and a flexible pipe that transfers thereto the compressed air coming from the caisson), installed offshore, each of which is subjected to different forces (the OWC and the upwelling pipe, and those of the waves that respectively impact them; the compressed air supply pipe, and those exerted by the motion of the caisson, of the upwelling pipe and by the water in which it is immersed), which makes necessary, with regard to the caisson and the upwelling pipe, the presence of distinct anchoring systems and, with regard to the compressed air supply pipe, the presence of systems for fixing said pipeline to the OWC and to the upwelling pipe. In addition, dedicated device are required which allow the three components to maintain their mutual position substantially unchanged in spite of the wave motion. Moreover, in all plants of this kind, the OWC caisson, to operate, uses, at least, a mechanical valve that allows, in the intake phase, the entry of atmospheric air into the caisson, in the compression phase, the flow of compressed air only inside the (upper) part of the upwelling pipe, which operates as an emulsifier tube. The above characteristics make this type of plant subject to wear and to risks of failure and, in any case, they impose frequent tests, operating checks, maintenance operations. Recently, attempts were made to overcome the aforesaid critical issues with a plant (patent application WO/2019/123330) that always uses wave energy to produce the compressed air necessary for the operation of the air lift but consists of a single block machine, lacking moving mechanical members and particularly solid. The limit of this machine is given, however, by the fact that with waves, whose significant height, in most months of the year, is lower than 2-2.5 meters, the compressed air produced in the caisson rarely exceeds the value of 1.5 atmosphere, substantially insufficient to raise large masses of water, also taking into account, in addition to head losses, the fact that deep water, given its temperature, is far denser than surface water. With regard to downwelling. In most cases, forced downwelling (as well as artificial upwelling) is carried out in OTEC plants to have available the warm water (and the cold water) necessary for the operation of the plant. For this purpose, as a rule, mechanical pumps are used. In the more limited cases in which, instead, the purpose to be pursued is only environmental (attempt to decrease “global warming”; to prevent the formation of hurricanes; to submerge large quantities of CO2), downwelling is, in general, caused by exploiting wave energy and, in particular, the potential energy deriving from wave height. For this purpose, the water that forms the crest of the wave flows, substantially by overtopping, and is collected inside floating tanks - whose edges are positioned at a greater height than that of the sea surface when it is still, but lower than the height reached by the crest of the wave when the sea is rough - from which, through a dedicated pipeline, then, they flow out towards the bottom, by gravity. The patent US20090173386 A1 by Jeffrey A. et al., in its essential core, is based on this principle. A fundamental limit of this type of plants is given, substantially, by the fact that, on one hand, they can use only the potential gravitational energy of the waves, and not also the kinetic energy, on the other hand, that they can only catch the limited part of the wave that rises above the edge of the caisson. These limits, as will be seen, are, instead, overcome by the pump of the present invention. With regard to the production of compressed air. The production of compressed air by means of a hydraulic compressor - also known as trompe or Taylor compressor, or also HAC (Hydraulic Air Compressor) is a technique known for centuries and widely used in the past, in particular in mines, to produce the compressed air necessary to cool tunnels positioned at great depth and to assure air exchange, as well as to actuate hammers or other machinery actuated by pneumatic devices. Currently, its use has been proposed again, both to exploit small waterfalls, to produce the compressed air necessary to actuate air turbines (see “Performance Analysis of Low Head Hydraulic Air Compressor”, Walid A.A., Salama Abdel-Hady M. et al., Smart Grid and Renewable Energy, 2010, 1, 15-24; Hydraulic air pumps for low-head hydropower”, Howey D.A. and Pullen K.R.; “Low-head hydroelectric power using pneumatic conversion, Bellamy N.W., in Power Engineering Journal, 1989 ”), and, more in general, as a more reliable, efficient, economical, non-polluting mode, with respect to current technologies for the production of compressed air (see “Mechanical Efficiency of hydraulic air compressor”, Pavese V., Millar D. and Verda V., in Journal of Energy Resources Technology 2016; Hydraulic Air Compressor (HAC) Demonstrator Project”, Millar d. and Muller E., ACEEE Summer Study on Energy Efficiency in Industry 2017). Pumps of this kind consists, fundamentally, of two tubes, of different length, installed, in vertical position and in fluid communication with each other, at the height of their lower ends, through a hermetically closed reservoir in which they both penetrate, in which a column of water that, given the difference in level between the two tubes, can circulate from the longer pipe to the shorter tube to exit, then, into the external environment, in the descending phase, it aspirates and progressively compresses the external atmospheric air which, once it is freed from water, is then collected in the upper part of the reservoir. This type of pump has no mechanical moving members, it is particularly robust and, substantially, it is not subject to failures or to wear. In addition, once it is started, it works uninterruptedly, with no need for adjustment or maintenance, as long as it continues to be powered by the water. Its efficiency is particularly high, exceeding that of any other type of compressor (it is approximately 60-70% and it can reach 80%), both because the compression of air can be considered substantially isothermal, because it occurs in close contact with the water that flows into the motor tube, and because, as stated, the compressor has no mechanical moving members. Moreover, the compressed air thus produced is particularly valuable because it is very dry and free of oily contaminants. Nevertheless, this type of hydraulic compressor has not, in fact, had great development on an industrial scale, inasmuch as its installation in a land environment (the only one where its construction has generally been conceived), to produce significant volumes of compressed air at adequate compression values in view of market needs (generally 7 or more atmosphere), is subordinated to the concurrent presence of three environmental conditions that are very difficult to find: 1. a body of water from which flow rates of several cubic meters per second can be drawn; 2. a waterfall of at least 10 meters (but preferably 15) between the level of the water that powers the motor tube of the hydraulic compressor and the one to which the water used in the process is discharged to the exterior; 3. a conformation of the ground, in the place where the water intake plant is situated, that allows, with no need for particular excavation works, for moving the soil and for building construction works, the installation of the motor tube of the hydraulic compressor in the vertical position, with the discharge outlet at a depth corresponding to the one at which the reservoir has to be placed - in relation to the pressure to which the air is to be compressed - i.e. the basis on which bears the column of water that rising from the exhaust pipe, flows out into the external environment. All these limitations, instead, do not apply if the pump is installed in a marine or lake environment and is made to operate creating an artificial and/or virtual geodetic fall between the height of the column of water mixed with air that flows in the motor tube and the one that rises in the exhaust pipe. In the hydraulic compressor of patent no. W02016/046689A1 – which is totally immersed in sea water - this virtual fall is achieved exploiting the energy of sea currents, forcing the water of the current to traverse, thanks to the kinetic energy possessed by it, if strong enough, or also to the thrust that is provided to it by a pump actuated by the current itself, a very large Venturi tube and making the water that operated the compression be discharged inside the narrow section of said Venturi tube. The fundamental limit of this type of hydraulic compressor, however, is given by the low efficiency of the suction system and by the consequent need, if significant volumes of compressed air are to be produced and allocated in the market, to install Venturi tubes of extremely large dimensions, with such construction and installation costs as to drastically reduce the advantages tied to the high efficiency of the hydraulic compressor and to the benefits connected with the use of free, clean energy. In the patent no. US3754147A, which also relates to a plant built in a marine environment, the hydraulic compressor instead is not fully immersed. The inlet of the motor tube that operates as a compressor is positioned at a greater height than that of the free surface of the sea when it is still but slightly lower than the height ordinarily reached by the crest of the wave when the sea is rough, so that the pressure drop used is the one that corresponds to this height difference, which as is acknowledged in the same patent, is, as a rule, of the order of just 1.5- 2 meters, and hence altogether insufficient to produce appreciable quantities of compressed air at significant compression values. In this regard, it should be considered that since the motor tube where compression takes place does not contain only water but also air, the pressure of the related column is a function of the density of the mixture present therein so that it will be the smaller, the greater the percentage of air. Thus, for example, if in a 100-meter high pipeline, the total percentage of air present in the mixture is equal to 10%, the hydrostatic pressure that can be exerted by this column is (at most) equal to 90 meters of water column. It is therefore evident that the water fall necessary for the plant to be able to work, taking into account head losses as well, will have to be around 15 meters. Advantages of the invention The plant of the present invention, in all sectors in which it can operate, is instead not subject to the limits and the critical issues pointed out with reference to existing machines in general, with respect to which it has particularly significant advantages. And in fact, both in the version that uses wind energy and in the one that exploits wave motion (even if it is characterized by an average wave height slightly above one meter), the plant is able to make available a pressure drop: - of approximately 9 meters, in the case of upwelling or downwelling; - of approximately 15 meters, in the version directed at the production of compressed air, and, hence, wholly adequate pressure drops to obtain the desired results. In addition, the plant, in the version that uses wave energy to actuate the suction pump, constitutes a static machine, inasmuch as it has no mechanical moving members Lastly - and this, too, is a feature that makes this plant particularly competitive with respect to all the other existing ones - in the plant can be installed and operate, both jointly and alternatively, both the aspirator actuated by wind energy, and the one moved by wave energy, which enormously broadens its possibilities of use. Brief description of the drawings The present invention is described below with reference to the accompanying drawings, which illustrate some, embodiments thereof, not limiting or binding, in which: - FIGURE 1 is a schematic lateral view, in vertical section, of an embodiment of the invention in the version of the plant directed at causing artificial upwelling, or downwelling, or downwelling with concurrent aeration of the sunken water, in condition of non-operation; - FIGURE 2 shows the plant per Figure 1 with the aspirator S in operation and the taps D1 and E1, which allow, regulate, prevent the flow of air at atmospheric pressure inside the plant, through the ducts D and E, closed; - FIGURE 3 shows the plant per Figure 1 in upwelling operation, with the aspirator S in operation, the tap E1 open, the other tap, D1, closed; - FIGURE 4 shows the plant per Figure 1 in downwelling operation, with the aspirator S in operation, the tap E1 closed and the other tap, D1, open; - FIGURE 5 shows the plant per Figure 1 with both taps E1 and D1 open, in downwelling operation with aeration of the water that is sunk; - FIGURE 6 is a schematic lateral view in vertical section of a version of the plant for the production of compressed air, showing the circulation of the water column that compresses the air from the descending pipe B1 to the reservoir 18 and, therefrom, through the rise and discharge pipe B2, inside the section A2 of the tubular chamber A, from which, by gravity, it flows out into the external environment; - FIGURE 7 is a highly schematic lateral view, representing a version of the plant in which the aspirator S1 consists of an Andreau wind turbine; - FIGURE 8 is a schematic lateral sectioned view of an embodiment of the plant, in which the aspirator consists of an artifact of annular shape that surrounds the tubular chamber A, which, given its particular conformation, can exploit the wave motion to create a Venturi effect inside it. Detailed description of some embodiments of the invention The description that follows intentionally refrains from dwelling on the technical details that for a person skilled in the art can be realized in various ways and that are, in any case, within his/her reach. Hence, the purpose of the present description consists of making it possible for the person skilled in the art to understand in general the invention and the related inventive concept, to implement it in its various embodiments, albeit with appropriate variants within the scope of the claims. In the version for upwelling and downwelling, the plant is characterized, in the first place, in that it consists of a hydro-pneumatic machine, partially immersed in a liquid body, in which upwelling or downwelling is obtained through an airlift pumping system that uses, as compressed air, air at atmospheric pressure, by virtue of the fact that the internal part of the system that is located above the free surface of the liquid body is housed in a space - a chamber open at its base, partially immersed, for some meters, in a liquid body - which one or more aspirators with which it is functionally connected maintain at a pressure lower than atmospheric pressure. Another, and no less important, feature of the plant is that it can operate indifferently, i.e. without any structural modification, but only depending on whether the air is made to flow, merely by opening/closing one or more taps, in one or other part of the plant, as a pump for upwelling deep water or for downwelling, i.e. sinking, and possibly aerating, surface water. Proceeding in an orderly manner, and with reference to the accompanying figures, FIGURE 1 shows, first of all, schematically, the general structure of the plant. In its essential core, the plant consists of: a chamber A, preferably of tubular shape, made of rigid, pressure-resistant material (in particular, able to withstand the pressure gradient exerted by the exterior air when the plant is in operation), open at its base (4), whose opening, as a rule, corresponds to its maximum diameter, partially immersed, in vertical position, in a liquid body (as a rule, the sea but also a lake), from which it projects for at least 20 meters. Said tubular chamber is watertight and can come in fluid communication with air at atmospheric pressure (6) only through the aspirator S and the ducts D and E, further described below. When the plant, i.e. the aspirator, is not in operation, as a rule the chamber A is filled with air at atmospheric pressure (6). The lower part (1) of the tubular chamber A is immersed in the (sea or lake) water under the free surface (2) indicated by the dashed line (for example for approximately 5 meters); at least, one aspirator S, which, as stated, is in fluid communication, in a part thereof, with the atmospheric air (6), in the other, with the inner upper part of the tubular chamber A, to which, as a rule, it is also connected materially, so as to form a single body. In Figure 1, the aspirator S is positioned at the top 3 of the tubular chamber A, but this is not binding. Thus, for example, in Figure 8, further illustrated below, the aspirator - that in this case consists of a water aspirator that exploits the Venturi effect - is installed in the lower part of the tubular chamber A. The function of the aspirator, or of the aspirators if more than one, is to maintain inside the tubular chamber a pressure lower than atmospheric pressure, possibly as low as possible. The aspirators are (preferably) actuated by wind energy or by sea wave energy, or also by both. The X inside the box of the aspirator S indicates that it is not in operation. In the plant may also be installed multiple aspirators, optionally, two - one actuated by wind energy, the other one by sea wave energy - both joined with the tubular chamber A so as to form a single body therewith. The aspirators can operate both simultaneously and alternatively, depending on the energy available at the time and they are provided with appropriate valves/devices that interrupt fluid communication with the outside environment, preventing the inflow of atmospheric air into the tubular chamber A, when they are not in function or if its condition of non-operation is accompanied by the condition of operation of the other aspirator or aspirators; a tubular body B. The body is hollow, open at the two ends (7 and 8), inner and coaxial to the tubular chamber A and it is partially immersed in the liquid body. Only its upper segment, also made with rigid material, projects from the free surface of the water by a variable height, depending on whether the plant is used for upwelling or for downwelling, from 11 to 18 meters. In Figure 1, the upper end 7 is positioned, but purely by way of example, at a height of approximately 14 meters from the free surface 2 of the water. This is because at this height, the tube can operate, indifferently, both for upwelling and for downwelling. The height at which the tube B is made to operate can be varied, providing appropriate means (not shown in the Figure) for adjusting the position of the upper end 7 of the tubular body B with respect to the free surface of the water 2, as coaxial sliding guides (radii) of the tubular body B in the tubular chamber A, a sliding sleeve applied to the end 7, etc. The depth to which said tube extends is not indicated because it can be the most widely varied. When the water to be upwelled are very deep, it is possible to join the tube B with another tube, C, flexible as a rule, which is fully immersed in water and which can be even many hundreds of meters long. Its lower end, 11, reaches the depth at which the water to be upwelled is located, or the one to which the surface water is to be downwelled; at least two ducts D and E (hereafter also indicated as first and second means for the injection of atmospheric air), which allow the external air (6) to flow into the tubular chamber A or the tubular body B. Said ducts are provided with appropriate taps, valves or the like, indicated with the letters D1 and E1, which allow to adjust, or to block, the flow of atmospheric air. These taps may not be simple on/off valves, but rather valves with multiples ways and multiple positions, flow regulators, flow sensors (for example, ultrasound), to indicate any failure conditions. The X affixed inside the circles that represent the taps D1 and E1 indicates that the taps are closed. Both ducts, at their inner end, are provided with appropriate diffusers (not represented in the drawing) that allow to diffuse, according to their conformation, atmospheric air inside the space 9 or 12, or, in the case of downwelling with concurrent aeration of the sunken water, of both. Thus, for example, in case of downwelling, the diffuser of the duct D can consist of a manifold of annular shape that surrounds the tubular body B, whose upper surface is traversed by holes that allow the atmospheric air to flow in the whole annular space 12 (and not just in the limited part indicated in Figure 1), directing it upwards; a system for anchoring the plant (not shown in Figure 1) to the bottom of the sea, lake, artificial basin, or the like, or to another fixed structure, or to a floating structure, which allows the plant to maintain the desired position and to withstand the force of waves and wind. Currently available technologies allow to carry out such anchoring even in the case of (sea) bottoms of many hundreds of meters and, therefore, the description will not dwell on these details, which are well known to a person skilled in the art; a series of mechanical devices (not shown in the Figure), which join together the various components of the plant, or only some of them, and which allow them to be configured as a single body. Since the tubular chamber A can be connected to several aspirators, some of them can be installed even at a distance therefrom. In this case, the connection between the tubular chamber A and these aspirators will only be fluidic through dedicated tubes. As stated, Figure 1 represents the upwelling and downwelling plant in non-operating conditions. In this situation, the space inside the tubular chamber A is also subjected to the same pressure (atmospheric pressure) existing externally because the aspirator S indicated in Figure 1 (being the sole one installed in the plant) is not provided with valves/devices that prevent the passage of air when it is not in operation. Therefore, since the part of the liquid body enclosed by the tubular chamber constitutes a system of communicating vessels with the part of the liquid body that is outside, the water level is the same both inside and outside said tubular chamber A, since, as stated, both spaces are subjected to the same pressure. When, instead, the aspirator is in operation (FIGURE 2), in the space delimited by the tubular chamber A, the pressure declines to values below that of atmospheric pressure; therefore, inside the tubular chamber A, and hence also inside the tubular body B, the water rises to a height in meters corresponding to the difference between atmospheric pressure and the pressure existing inside the chamber A, and hence, when the internal pressure is stabilized around 0.1 atmospheres, to a height of approximately 9 meters (in fact, in the tubular body B to no more than 8 meters when it is made to operate for upwelling, given the higher density of deep water because of its low temperature relative to surface water). In FIGURE 3, the plant is shown in the upwelling function. Here the system is in the following configuration: - aspirator S in operation; - tap E1 open (empty circle); - tap D1 closed (circle with cross “X”). Consequently, since the space inside the plant is at lower than atmospheric pressure, in this hypothetical case, as stated, at 0.1 atmospheres, the air naturally flows, given the higher pressure, through the duct E, into the tubular body B, at immediately greater height than the free surface of the external water, creating an air-water mixture (in Figure 3, air bubbles are indicated with small circles, 16, the water present in the mixture with small dashes) that, if at 50%, although it can rise up to 18 meters, in effect, upon reaching the upper end of the tubular body B, which is at 14 meters, flows out of it and into the tubular chamber A, forcing the surrounding annular column of water to sink (arrows Q in Figure 3), while the bubbles 16 separate and are ejected, by the aspirator, into the outside environment. In correlation, as indicated by the curved arrows F in Figure 3, deep water containing nutrients (nitrates, phosphates, silicates, etc.) rise in the flexible tube C and, then, in the tubular body B, and this artificial upwelling process continues until the aspirator S is in operation. It should be noted that the drawing is obviously not to scale inasmuch as the flexible tube C can descend into the water even down to many hundreds of meters while the plant could be approximately 20 meters high above the free surface 2, i.e. substantially of this order of magnitude as a number provided purely by way of non-binding example. In FIGURE 4, the plant is shown in the downwelling function. Here the system is in the following configuration: - aspirator S in operation; - tap E1 closed (circle with cross “X”); - tap D1 open (blank, i.e. empty, circle). The dynamics of the downwelling process is exactly inverse to that of upwelling. In particular, atmospheric air naturally flows into the tubular chamber A, passing through the duct (or the ducts) D, creating an air-water mixture (in this hypothesis, also at 50%) which rises to a greater height than the upper mouth 7 of the tubular body B. The air bubbles 16 are aspirated by the aspirator S and ejected outwards while the water, separating therefrom, falls back inside the tubular body B, causing the sinking of the column of water present inside it (arrows R in Figure 4). Obviously, the water of this column exits, as indicated by the arrows V, from the lower end 11 of the flexible tube C (Figure 4). The sunken surface water (arrow T) is progressively replaced by the less warm underlying water, thus reducing the temperature of the surface water. FIGURE 5 shows the plant in downwelling operation with concurrent aeration of the sunken water. The operation is similar to the one illustrated in the preceding Figure 4, with the only variant that the tap E1 is open as well, but so regulated as to allow the flow of a smaller quantity of air than the one that flows in the upwelling operation shown in Figure 3. However, in this case the bubbles 16’, flowing into the descending water column in the tubular body B and having reduced flow rate, are driven downwards (arrows R). The water of this column, as pressure grows in the descent, absorbs progressively more air until saturation; lastly, exiting from the tubular body, together with the compressed air that has not been absorbed, contributes to oxygenate the water of the surrounding outside environment (which can be particularly useful with regard to lake restoration). FIGURE 6 refers to the version of the plant directed at the production of compressed air. In this version - which constitutes a variant of the one relating to upwelling and downwelling - the plant is configured at an open circuit hydraulic air compressor, powered by the same water of the liquid body in which it is fully immersed. The plant comprises among its components, in the first place, a tubular chamber A and an aspirator, already described in regard to Figure 1. However, in this version the tubular chamber A is divided in two separate sections, A1 and A2, through a vertical dividing wall P, which extends above the free surface of the water to approximately 19 meters of height. In the segment that emerges from the water, therefore, there is not direct communication between the two sections A1 and A2, except in the upper part of the tubular chamber A, where the vertical dividing wall P is interrupted (point indicated with the numeral 17), i.e. where both sections A1 and A2 join each other and towards the aspirator S, so that each of the two sections, in effect, operates as the tubular chamber A per the preceding Figures 1-5. In section A1 is present the motor tube, i.e. the tube inside which the hydraulic compression of air takes place. The motor tube consists of a tubular body, B1, open at the two ends, upper (7”) and lower (8”) and almost fully immersed, in vertical position, in the liquid body. The immersed segment of said tubular body extends downwards to a hermetically closed reservoir (18), into which it penetrates to reach slightly below the upper wall thereof; the segment that projects from the free surface of the water extends, inside the section A1, for a height of approximately 17 meters. As stated, the function of said tubular body is to operate as a motor tube. Therein, the column of water that operates the compression of the aspirated air flows downwards to the reservoir (18), through a duct, E”, from the exterior. In the section A2 is present the tube for the rising and discharge of the water that operated the compression. Said tube consists of a tubular body, B2. It too is open at the two ends, upper (7’) and lower (8”), it is almost completely immersed, in vertical position, in the liquid body and extends downwards, to the same reservoir (18) in which the tubular body B1 penetrates, but, differently therefrom, it penetrates more deeply inside it, to stop slightly above the bottom, so as to always be below the free surface of the water that collects in the reservoir. The segment that projects from the free surface of the water extends, inside the section A2, for a lower height than that reached by the tubular body B1; as a rule, it stops at a height of approximately 10-11 meters. As stated, the function of said tubular body B2, which as a rule has a greater diameter than that of the tubular body B1, is to allow the rise of the water that operated the compression from the bottom of the reservoir to the height at which it has to be discharged. The plant further comprises three ducts D’, E’ and E”, for the injection of atmospheric air inside, respectively, the section A1 of the chamber A, of the rising tube B2, and of the descending tube B1. In the first case, to create the air-water mixture, as a rule 50% which, rising to the height above that, of 17 meters, at which the inlet of the motor tube is positioned, powers the plant with the water that, having separated from air, falls downwards by gravity; in the second case, to reduce the density of the water present in the last 16-17 meters (approximately) of the rising tube, thus starting its exit from said tube; in the third case, to inject into the motor tube the atmospheric air to be compressed. In all three cases, the injection of the air takes place, as a rule, at a height slightly greater than that of the free surface of the water exterior to the plant, and, therefore, in an environment in which the pressure is lower than atmospheric pressure. Each duct is provided with appropriate taps/valves, respectively D1’, with regard to the duct D’; E1’, with regard to the ducts E’; E1”, with regard to the duct E”. These taps allow, regulate, block the inflow of the atmospheric air. At the inner end of each duct are installed diffusers (not shown in the drawing, with the exception of the one pertaining to the duct E’) which distribute atmospheric air into the space according to their conformation. Thus, for example, with regard to the duct D’, the diffuser, as a rule, will have the shape of a holed ring that surrounds the tubular body B1, thus allowing to distribute uniformly the air injected by the tap/valve D1’ in the substantially annular cylindrical space delimited, in section A1, by the tubular body B1. Another component of the plant is a reservoir (18), positioned at its lower end. The reservoir has the dual function, on one hand, of collecting, on the bottom, the water that, after operating the compression, projects from the motor tube and, in the upper part, the compressed air that was freed from the water; on the other hand, of placing in fluid communication the motor tube with the rise and discharge tube. In fact, when the level of the water, that collects on the bottom of the reservoir, overcomes the inlet of the rise tube B2, i.e. its lower ends, the pressure exerted by the overlying compressed air forces it to rise in the tube B2. Since the pressure to which the air can be compressed is given by the pressure exerted by the water column and by the air-water mixture present in the rise tube it is evident that to produce compressed air at a determined pressure, the reservoir will have to be installed at a depth corresponding to the height of said column. Another component of the plant is a long tube (not shown in the Figure), which fluidically connects the upper part of the reservoir (18) to the place of utilization/storage of the compressed air that has been produced. Said tube is provided with appropriate valves/pressure sensors, which allow, prevent, regulate, in relation to the pressure existing inside the reservoir and/or place of utilization/storage of the compressed air, the flow thereof. With regard to the operation, the circulation of the water column in the plant, from the descending tube B1 (motor tube) to the reservoir (18) and therefrom, through the rise and discharge tube (B2), in the section A2 of the chamber A, and, hence, in the external environment, is obtained thanks to the creation of a geodetic drop of approximately 15 meters (of which 8-9 virtual) between the inlet 7” of the motor tube and the discharge outlet of the rise tube 7’. This drop is created by two airlift pumps, one of which raises the water present in the section A1 to the inlet 7” of the motor tube, and it is realized with the injection of the atmospheric air, through the duct D’, in the water column present in the space - in effect, an actual pipeline with substantially circular crown shape - delimited, inside the section A1, by the tube B1; the other airlift pump reduces, by approximately 50%, the density of the water that rises in the last 16-17 meters of the rise and discharge pipe B2, through the injection of atmospheric air in the upper segment of the tube B2, through the duct E’. The hydraulic compressor is also characterized in that the two airlift pumps use, like the upwelling and downwelling plant, air at atmospheric pressure as compressed air. This is made possible by the fact that both the segment of the descending tube (i.e. of the motor tube), and the segment of the ascending tube (i.e. the rise and discharge tube), which project from the liquid body, for approximately 17 meters, the former, and 10-11 meters, the latter, are housed in a space - the two distinct sections of the tubular chamber A - in which one or more aspirators maintain a pressure lower than atmospheric, as a rule around 0.1 atmospheres. This entails that - as has already been illustrated with regard to the plant for upwelling downwelling - when the aspirator is in operation: - the water rises inside the chamber A (and, hence, in this case, in both sections into which the chamber is divided), to the equilibrium height and, hence, with a vacuum of 0.1 atmospheres up to 9 meters; - for its part, the external air, given the greater pressure, can flow, through the appropriate ducts, both inside the section A1 in which the higher segment of the motor tube is housed, and inside the rise and discharge tube B2, so as to form, with the water present therein, a 50% air- water mixture; - said mixture, in the section A1, rises to a height of approximately 18 meters, thus powering, with the water that, having separated from the air, falls by gravity downwards, the underlying motor tube; in the tube B2, it reduces the density of the water present in the last 16-17 meters thereof thus starting the exit of the mixture from the tube and the consequent sinking of the water present in the section A2; - in turn, the air, as it progressively separates from the mixture that was formed both in the section A1 and in the rise and discharge tube, is transferred outside through the aspirator S. To increase the pressure drop between the water column that descends in the tubular body B1 and the one that rises in the rise tube B2, a small part of the compressed air that is produced can be blown, through an appropriate duct (not shown in the Figure) that joins the upper part of the reservoir with any interior segment of the rise tube, thus further reducing the density of the water column present in the rise tube. This, obviously, reduces the quantity of compressed air that can be used for other purposes but makes the velocity of circulation of the water in the plant enormously more efficient. FIGURE 7 is a very schematic lateral view of a version of the preceding embodiments of the invention. The reference symbols are those of the preceding figures with the exception of the details relating to the aspirator S1. In this case, the aspirator consists of an Andreau wind turbine, whose tower (which substantially coincides with the tubular chamber A), whose hub, 22, and whose blades, 23, are hollow, and the latter have openings, 23a, at their ends. This entails that, when the blades are moved by the wind, the centrifugal force expels the air present therein, and since there is an internal communication between the tower A, the hub and the blades, a continuous flow of suction air is generated - the air that progressively flows into the plant to actuate the airlift pumping system - that allows to maintain within the tubular chamber A (which, as stated, coincides with the tower) a pressure lower than atmospheric pressure, for example of 0.1 atmospheres. This aspirator may be the only one installed in the plant or it may operate with one or more others, for example with the one actuated by wave motion, to be described when illustrating Figure 8. In this latter case, i.e. when there are multiple aspirators in the plant, in the blades of the wind turbine, at the height of their ends, are installed appropriate devices/valves that close, when the turbine is not in operation, the openings, 23a, present in that point of the blades, thus preventing the external atmospheric air from penetrating inside the plant. FIGURE 8, lastly, represents (also schematically and in section view) another type of aspirator, which, like the one shown in Figure 7, is actuated by natural energies, in this case by wave motion energy. Like the aspirator actuated by wind energy, per Figure 7, this aspirator too can be installed in both versions of the plant, i.e. both in the one for upwelling and downwelling and in the one for the production of compressed air. Moreover, it can be installed in a plant in which is already present the wind aspirator per Figure 7 and operate jointly therewith. Said configuration gives enormous advantages, both with regard to the efficiency of the plant, because the simultaneous operation of two aspirator obviously increases the aspiration capacity and, and above all, the continuity of operation of the plant, because the loss of one of the two energies (wind and wave motion) used by the aspirator does not entail the stoppage of the plant in the presence of the other. This aspirator is essentially a Venturi water aspirator. The aspirator exploits the flow of the waves forced to pass in an artifact whose section corresponds to the one of a Venturi tube, to obtain the vacuum necessary to aspirate (through appropriate ducts) and, hence, to transfer to the outside environment the air that, after flowing into the tubular chamber A and having operated as compressed air, in the airlift pumping system present in its interior, expands inside said chamber. A fundamental feature of this marine aspirator is given by the fact that it: - can operate, maintaining very low pressures (even lower than 0.1 atmospheres) in the tubular chamber A even with waves of very limited height (even of only 1 or 2 meters); - is able to aspirate enormous quantities of air. And in fact, on one hand, the vacuum that can be created inside the narrowed region of the artifact does not depend on the height of the water column that flows inside it, but on the narrowing ratio; on the other hand, the volume of air aspirated is tied to two factors: the dimensions and the shape of the artifact, which depend only on the choice of those who build it; the quantity of water that can flow inside it, which consisting of sea wave water, can be considered substantially unlimited for this purposes. Figure 8 represents, as stated, one of the possible embodiments of such a water aspirator and therefore it does not limit all the others that can be embodiments within the scope of the present invention. As the drawing shows, in this embodiment the water aspirator fundamentally consists of an artifact of annular shape, partially immersed in the liquid body, formed by two opposite walls 25’ and 25”, convergent divergent, whose section corresponds to that a Venturi tube. It is open at the two ends, upper and lower, and it surrounds the tubular chamber A, in a part thereof, above, in the other one, below, the free surface of the water. It is joined (when it is metallic, for example welded) thereto so as to form, with said tubular chamber A, a single body and hermetically to close the space 28 existing between the two structures. The divergent segment, which develops above the free surface of the water, projects therefrom, for a height correlated - for example in a ratio of 2/5 - to the average height of the waves recorded on site. This height could even be much greater if the artifact is realized within, and as a component of, an overtopping structure. In this case, moreover, its operation would not be closely tied to the period of the waves but also to the quantity of water that can be accumulated in the related structure. The inner wall 25”, in the limited segment 26 of approximately 50 cm (corresponding to the maximum narrowing of the artifact), which extends by 25/30 cm above and by an equal distance below the free surface of the water when the sea is calm, is traversed by numerous holes 27. Said holes put in fluidic communication the hollow inner space 28 - otherwise hermetically closed - existing between the inner wall 25” of the aspirator and the wall 13 of the tubular chamber A. In turn, this space 28 is put in fluidic communication with the upper inner part of the tubular chamber A by an inner tube 29 (or by multiple tubes) appropriately joined thereto and open at the two ends. The lower end of said tube 29 (or tubes) penetrates inside the space 28, traversing the wall of the tubular chamber. Its upper end reaches, instead, as stated, the upper inner part of the tubular chamber A. Said tube 29 when the water aspirator S2 is intended to operate together with others is provided with appropriate devices/valves that when the water aspirator is not in operation interrupt the fluidic communication with the outside environment, preventing atmospheric air from flowing inside the tubular chamber A. As stated, the principle of operation of this aspirator is that of any Venturi water aspirator, in this case tied to wave motion. This means that when a wave, of sufficient height, rises over the upper edge of the artifact, the mass of water that descends downwards creates, in the narrowed region 26, a vacuum in relation to which is aspirated - and hence driven into the outside environment, by the water the exits from the lower end of the artifact - first of all, the air present in the space, 28, existing between the inner wall of the aspirator and that, 13, of the tubular chamber A; and, hence, the one present in the upper segment of the tubular chamber A, which progressively flows in said space 28 through the duct 29. Obviously, this process continues uninterruptedly as long as the aspirator is in operation. List of reference symbols 1 lower part of A 2 free surface 3 top of A 4 lower opening of A 5 interior of the tubular chamber A 6 exterior of A, atmospheric air 7 upper end of B 7’ upper end of B2 7” upper end of B1 8 lower end of B 8’ lower end of B2 8” lower end of B1 9 inner space of B 10 upper end of C 11 lower end of C 12 (annular) space between A and B 13 wall of the tubular chamber A 14 wall of the tubular body B 14’ wall of the second tubular body B2 14” wall of the first tubular body B1 15 second level of the water (equal in A and in B) 16 air bubbles/molecules 16’ air bubbles for aeration (Fig. 5) or for compression (Fig. 6) 17 point of interruption of the dividing wall P (Fig. 6) 18 submerged reservoir 19 bottom 20 mass of water in the submerged reservoir 18 21 space occupied by the compressed air in the submerged reservoir 22 turbine hub 23 turbine blades 23a openings of the blades 23 24 anchoring structure 25’ outer wall of the artifact (Fig. 8) 25” inner wall of the artifact (Fig. 8) 26 narrowed limited segment of the Venturi (Fig. 8) 27 holes of the limited segment 26 (Fig. 8) 28 space between A and S2 29 aspiration tube/duct (Fig.8) A tubular chamber A1 first section of A A2 second section of A B tubular body B1 first tubular body B2 second tubular body C flexible tube E duct (of the tubular body B) E1 tap/valve E’ duct (of the second tubular body B2) E1’ tap/valve E” duct (of the first tubular body B1) E1” tap valve duct (of the tubular chamber A) D1 tap/valve D’ duct (of the section A1 of the tubular chamber A) D1’ tap/valve P dividing wall F flow arrows Q flow arrows R flow arrows V flow arrows T flow arrows X closed condition (aspirator or tap) S aspirator (Figs. 1-6) S1 aspirator (Fig. 7) S2 aspirator (Fig. 8)