WO2008084507A1

WO2008084507A1 - Production system of electricity from sea wave energy

Info

Publication number: WO2008084507A1
Application number: PCT/IT2007/000547
Authority: WO
Inventors: Leonardo Galloppa
Original assignee: Lopez, Francesco
Priority date: 2007-01-10
Filing date: 2007-07-31
Publication date: 2008-07-17
Also published as: ITCH20070002A1

Abstract

A production system of electricity from sea wave energy comprises: a submarine structure that supports columns emerging from the sea. Floats provided with slides or sliding wheels are attached to the columns and moved vertically by the waves. A force is produced and transmitted to pneumatic pistons that are vertically arranged along the column. The consequent production of compressed air, the excessive quantity being stored, is used to alternatively feed two tanks that pressurise the oil of the hydraulic circuit and are alternatively used as tank to power the motor or tank as recover the discharged oil. The pressurised oil is used to power one or more hydraulic motors connected to AC generators.

Description

Production system of electricity from sea wave energy.

Description

The present invention relates to a production system of electricity from sea wave energy.

The plants that have been realised or studied so far according to the known technique use the sea wave energy to actuate devices that convert mechanical energy into electrical energy.

For example, the sea wave energy is typically used to actuate rotors connected to an alternator for the production of electricity.

However, the solutions according to the known technique are impaired by some drawbacks: the immediate transformation of the hydromechanical energy into electricity affects the power that is produced and delivered; in fact the systems or plants according to the known technique are strictly related with sea conditions for their operation.

In case of storms or high waves the systems according to the known technique are not able to take and transform the kinetic energy of the waves into electricity and they must be often deactivated to avoid damages to the system.

The large quantity of energy that could be taken in very rough sea conditions is actually wasted by the systems according to the known technique, since they are not able to extract it efficaciously and efficiently in relation to the installation costs.

Other systems according to the known technique provide for the generation of compressed air from the wave energy, using docks or piers to compress the air, which is then used in double-effect machines. This solution, however, is impaired by considerably high installation costs that discourage installation except for places without high, constant wave energy; in fact, in these cases it is necessary to realise structures, such as piers or docks, that have very high installation costs, together with an unacceptable environmental impact in the majority of cases. A further inconvenience of the systems according to the known technique is given by fact that the kinetic energy of the wave energy is not transformed in such a way as to permit accumulation for later use.

The purpose of the present invention is to provide a production system of electricity from sea wave energy able to overcome the aforementioned inconveniences.

The present invention relates to a production system of electricity from sea wave energy that comprises:

- at least one support structure for at least one emerged or emergible column; - at least one float that slides along the column;

- the float is operatively connected to a pneumatic piston for the production of compressed air;

- the compressed air is at least partially conveyed by means of a pneumatic circuit to at least one first tank, being the first tank in active phase, that is to say feeding at least one hydraulic motor by means of at least one hydraulic circuit;

- the hydraulic motor/s is/are operatively connected to at least one alternator for the production of electricity.

According to the present invention, the kinetic energy of the waves is taken by means of a float that compresses a pneumatic piston, generating compressed air that is used to pressurise a tank that contains a fluid, for example oil, which is sent to a hydraulic engine connected to an alternator or generator.

The conversion of the kinetic energy of the waves is suitable for low cost installations, which can be realised in open sea to use the energy of the waves, while reducing the environmental impact and storing energy in a simple economic way: in fact, the compressed air can be produced and stored in a simple, inexpensive way in suitable storage tanks, as described below, in order to be used when the sea is calm. The presence of at least one hydraulic motor ensures high efficiency and allows to use the wave energy in a very convenient way.

In the specific case of the executive version described and illustrated below, the system according to the present invention is composed of a structural part exposed to sea conditions and a hydropneumatic circuit that feeds a current generator.

To take better advantage of the wave energy, the system is adapted to the different sea conditions, with dynamic variations caused by tides, wave height and frequency.

These variables make the structure operate at different work heights and the same hydraulic and pneumatic circuit, or hydropneumatic, must be capable of having different configurations. The adaptation is obtained by means of mechanical and fluidodynamical systems.

Considering the existence of seas characterised by prevalently rough and shallow waters, a careful selection of the geographical location for the installation and a careful dimensioning of the structural components will allow to obtain considerable quantities of energy and constant production. The system according to the present invention can be advantageously applied to existing platforms that are used for different purposes, in order to provide them with energy autonomy or, alternatively, multiple systems can be realised, that is to say composed of a plurality of systems according to the present invention, with multiple productive units applied to the same support structure, possibly in submarine installation.

The geometrical configuration of each group of productive units advantageously uses the passage of the same wave in different points; moreover, a series of systems can be realised with a series of satellite productive units with independent operation, and a central system that receives and transforms the energy produced by the same units according to a modular configuration.

Furthermore, this system advantageously allows to store the wave energy, converting the part of wave energy that is excessive for the installation in case of storms into a potential reserve, and recover a good part of the energy that is not used by the circuit for functional reasons.

According to the preferred executive version illustrated below, the system according to the present invention provides for the construction of a structure on the sea bottom, with one or more floats attached to the emerging part. The floats are free to move in vertical direction, floating on the sea surface, and are pushed upwards by the waves, producing a force that is proportional to the weight of the water volume that is necessary for floating. This force is applied or transferred to pneumatic pistons attached to the structure for the production of compressed air.

According to the preferred executive version illustrated below, by means of a directional-control valve, the compressed air is alternatively sent to two pressurizable tanks that transfer the pneumatic pressure to the hydraulic oil contained in the tanks.

The oil is then sent to power a variable volume hydraulic motor applied to an electrical alternator.

Further characteristics are the subject of the enclosed claims and subclaims. The present invention will become clearer with reference to the enclosed drawings, whereby:

- fig. 1 shows a support tower structure used to support the columns according to the present invention;

- fig. 2 shows a support tower structure with submergible column support attached to internal guides according to the present invention;

- fig. 3 shows a support tower structure with submergible column support attached to external guides according to the present invention;

- fig. 4 shows a submergible support tower structure anchored to the sea bottom according to the present invention; fig. 5 is a sectional view of the preferred circular layout of two concentric series of columns supported by a submergible platform attached to the external guides of the tower according to the present invention;

- fig. 4 is a side view of a column with corresponding float and pneumatic piston according to the present invention; - fig. 7 is a side sectional view of a float according to the present invention;

- fig. 8 is a detailed view of a sliding means between floats and column according to the present invention; - figs. 9 and 10 show two different executive versions of the housing for the column provided in the float according to the present invention;

- fig. 11 shows a first executive version of a piston according to the present invention, being the so-called straight piston; - fig. 12 shows a second executive version of a piston according to the present invention, being the so-called overturned piston;

- fig. 13 shows an executive detail of a piston according to the present invention;

- fig. 14 shows an alternative executive version of a piston according to the present invention, being the so-called piston with mobile bottom;

- fig. 15 is a side view of a column and of the upper and lower crowns according to the present invention;

- fig. 16 is a plan view of a column and of the upper and lower crowns according to the present invention; - fig. 17 shows an executive detail of an advantageous executive version of a crown according to the present invention;

- figs. 18 and 19 show the combination of a mobile upper crown and a so- called overturned piston;

- fig. 20 shows a column provided with hydraulic positioner piston according to the present invention;

- figs. 21 , 22, 23 and 24 show an upper crown provided with a rotating ring with internal thread, screwed on toothed bars in vertical position along the column;

- figs. 25, 26, 27 and 28 show an alternative executive version of an upper crown provided with a rotating ring with internal thread, screwed on toothed bars in vertical position along the column;

- figs. 29, 30, 31 show an additional executive version obtained with four vertical female screws screwed onto corresponding passages in the mobile crown; - figs. 32 and 33 show an alternative position of a mobile crown on overturned pistons;

- figs. 34 and 35 show the combination of a mobile upper crown and a so- called straight piston;

- figs. 36 and 37 show the combination of a fixed crown coupled with a piston with mobile bottom;

- figs. 38 and 39 show the combination of a fixed crown coupled with a piston with mobile bottom, being the so-called overturned piston;

- figs. 40 and 41 show a combination of a fixed crown associated with a submergible platform or submergible support structure anchored to the sea bottom;

- figs. 42 and 43 show a combination of a fixed crown and a so-called submergible internal-guided platform;

- fig. 44 shows a combination of a fixed crown and a so-called submergible external-guided platform;

- fig. 45 shows a diagram of the hydropneumatic circuit according to the present invention; - fig. 46 shows an executive version of a tank for compressed air with variable volume and constant pressure according to the present invention;

- fig. 47 shows an alternative executive version of a tank for compressed air with variable volume and constant pressure according to the present invention. Fig. 45 shows a preferred executive version of the system according to the present invention.

The operating principle of the system is described below: by means of a directional-control valve (36), the compressed air coming from the pneumatic piston through the pneumatic circuit is alternatively sent to two pressurizable tanks (31 , 32) that transfer the pneumatic pressure to the hydraulic oil contained in the tanks.

The oil is then sent to power a variable volume hydraulic motor (38) applied to an electrical alternator that produces electricity.

The oil introduced in the motor (38) comes from a pressurizable tank (31 ), full of oil in the figures, which is pressurized with compressed air by means of the pneumatic directional-control valve (36).

The oil expelled by the motor (38) is recovered in the tank (32) by means of the hydraulic directional-control valve (37) and the tank (32) that is being filled is maintained at atmospheric pressure until it is full, in order not to hinder filling.

When the tank (31) is almost empty, the tank (32) is full and therefore the pneumatic directional-control valve (36) pressurises it, while advantageously discharging the residual pressure in the tank (31) up to the atmospheric pressure. During this event, part of the air pressure is recovered in the reserve tanks (34) by means of the pneumatic circuit.

Practically, the pneumatic directional-control valve (36), which is controlled according to the oil level in the tanks, alternatively transforms either of the two tanks (31 , 32) from power source of the motor (38) to recovery tank for the discharged oil.

The valve (36) operates together with a hydraulic directional- control valve (37) designed to sort out the oil coming in and out between the motor and the tanks (31 , 32).

Both valves (36, 37) are advantageously and simultaneously operated by the same impulse to avoid discontinuity in powering the motor during the change. Valves with proportional opening are advantageously provided, together with a piston accumulator installed upstream the motor, whose operating pressure is set by the compressed air of the pneumatic circuit.

Assuming that the motor system is dimensioned according to intermediate sea conditions between calm sea and a storm, pressurizable tank systems (34) are provided and powered by the excessive pressure in case of storms in order to generate an energy reserve that will power the generators when the sea is calm.

The reserve can be obtained in different advantageous versions and is a preferred solution to ensure constant production.

A version of a tank for compressed air with fixed volume and variable pressure and two solutions of a tank for compressed air with variable volume and constant pressure are advantageously described and illustrated below. Figs. 1 , 2, 3, 4 illustrate four advantageous executive versions of a support structure used to support at least one column (5), either emerged or emergible, provided with at least one float (6) with possibility to slide, being operatively connected to a pneumatic piston (7) for production of compressed air.

In particular, fig. 1 shows a typical tower structure (1 ) anchored to the sea bottom, while fig. 4 shows a variant of the support structure in the executive version of a submergible platform (2) that is prevented from emerging and translating by means of cables (3) anchored to the sea bottom.

Alternatively, as shown in figs. 2 and 3, the submergible platform can be immersed inside and/or outside the tower (4) that acts as a guide.

The emerging part of the support structure is composed of one or more columns (5), in which floats (6) are inserted to compress the pneumatic pistons (7) when pushed upwards by a wave.

The columns (5) may have any type of section, preferably a circular or polyhedric section. In case of columns with a polyhedric section, the presence of the sliding guides between the column and the float to prevent the float from rotating with respect to its vertical axis, as described below, is advantageously avoided.

In case of multiple columns (5), each of them being provided with a float (6) and corresponding pneumatic piston (7), the circular arrangement of the columns (5) with respect to the support structure (2) is especially advantageous, as shown in fig. 5, since it permits to use the passage of a single wave in different points, regardless of its direction.

Fig. 6 is a side view of a column (5) with float (6) and corresponding pneumatic piston (7).

This is basically the core of each production unit of compressed air and is composed of a column (5), a float (6) and one or more pneumatic pistons (7) with upper (8) and lower (9) attachment brackets, in crown configuration, being the so-called upper (8) and lower crown (9).

In particular, fig. 6 shows the preferred solution of multiple pistons that are operatively connected to the same column (5) by means of the said upper (8) and lower crown (9), in the three moments that correspond to the passage of the wave.

Figs. 7, 8, 9, and 10 show the preferred advantageous executive version of a float (6).

The dimensions of the float determine the useful force that is divided among different pistons. The shape and volume of the float are important to take advantage of waves in any sea conditions.

As shown in fig. 7, the float has a spheroidal shape with slightly flattened poles to improve flotation and hydrodynamic penetrability.

The circular section allows the float to advantageously work with waves from any direction and offers a lower hydrodynamic resistance when the float is submerged by the wave in rough sea conditions.

The float (6) is provided with an opening (10) or housing, with cylindrical or any other suitable section, along its vertical axis used to insert the float (6) in the columns (5).

When the float (6) is raised by the waves, it moves vertically along the column (5). The opening (10) where the float (6) and the column (5) are interfaced is internally provided with a series of sliding guides, such as, without limitation, wheels or trolleys (11 ) that make vertical movements easier. Vertical sliding guides (12) are inserted in case of circular columns.

The top of the float (6) is provided with brackets or lower crown (9) for the lower attachment of pistons (7), which are preferably arranged in circular configuration around the column (5). In the preferred solution the lower attachment crown (9) is circular.

Fig. 9 shows a float (6) with a cylindrical opening (10) or housing provided with sliding means (11 ), while fig. 10 shows a float (6) with a polygonal opening (10) or housing, with quadrangular section, provided with sliding means (11 ). Figs.11 , 12, 13 and 14 show different executive versions of pneumatic pistons according to the present invention.

The pneumatic pistons basically transform the vertical force of the float in compressed air.

The pneumatic piston comprises a stem (13) that slides inside a cylinder (14) and ends inside the cylinder with a plunger (25), while the cylinder ends with a bottom (15) at the opposite end with respect to the coupling end of the stem.

Pressure is obtained when the height of the bottom (15) of the piston is accurately related with the maximum flotation height of the float. The height varies according to different sea conditions and, for this reason, alternative executive versions are provided to advantageously vary the vertical position of the bottom (15).

Fig. 11 shows a first executive version of the piston, i.e. the so- called straight piston, in which the piston is positioned with the cylinder (14) in lower position and connected to the float by means of the lower crown, while the stem (13) is positioned in upper position and connected to the upper crown. According to this first executive version of the piston, as shown in fig. 13, the air in the top of the stem (13) is intercepted, by providing a delivery pipe (48) inside the stem (13) and using the residual internal volume (49) for intake. Intake valves (29) and delivery valves (30) for the air are provided in the thickness of the plunger (25). Fig. 12 shows a second executive version of the piston, i.e. the so- called overturned piston: this piston is in opposite position with respect to the straight piston and is provided with a stem (13) connected to the float (6) by means of the lower crown (9) and the cylinder connected to the upper crown (8). The air is intercepted at the top of the cylinder (14), and therefore the intake valves (29) and delivery valves (30) are positioned in the bottom (15).

According to another alternative and advantageous executive version shown in fig. 14, the piston has a mobile bottom (26) that slides inside the cylinder.

In this advantageous executive version, the piston can adapt to the height of the waves by varying the volume of the compression chamber.

Basically, by pumping the filling oil (27) inside the cylinder liner (14), the position of the mobile bottom (26) can be varied to reach the height of the top dead centre of the plunger (25), thus changing the internal volume and the volumetric capacity of the piston.

If the waves tend to get bigger, the plunger moves the bottom to the new top dead centre, thus ejecting the necessary quantity of oil. The filling oil circuit (27) can be independent and fed by a pressurized tank or, alternatively, by a hydraulic shock-absorber (45) capable of pushing oil inside the cylinder (14) and recover it when it is ejected.

Furthermore, a pilot-operated valve (44) is provided to block the oil coming out of the cylinder, thus setting the mobile bottom (26) in position during the intake and compression of the air.

If the waves get smaller, the same valve permits to introduce oil in the cylinder to replace the mobile bottom (26) at a lower height.

Figs. 15, 16 and 17 show the upper and lower crowns used to fix the pistons. According to the preferred and illustrated executive version, the lower (9) or upper (8) crown is a simple circular series of perforated plates that is used to fix the pistons. The lower crown (9) is basically positioned at the top of the float (6) and the upper crown (8) can be provided with the possibility to move along the vertical axis of the column (5), being attached to it.

According to an advantageous executive version, in order to prevent that sudden variations in the plunger travel can cause damage to the components of the pistons, such as the bottom (15) or mobile bottom (26) against the plunger (25), a crown of brackets fixed by means of a sliding guide (47) and provided with spring shock-absorber (46) can be provided.

The actuation of the shock-absorber (46) and the measure of the travel covered by the shock-absorber (46) can be considered as command for temporary adjustment to the sea conditions.

The maximum height of the wave determines the height of the top dead centre of the piston, and therefore it is preferable to move the bottom (15, 26) of the piston vertically (15,26), where the air is compressed, in order to position it the proximity of such a point. In this way, the volume of the compression chamber of the cylinders is related with the travel, thus using the strength of the wave at best.

The following alternative executive versions advantageously solve the adaptation problems of the structure according to variable sea conditions, by changing the height where air is compressed inside the pistons.

The different alternative executive versions provide for the following characteristics, either alternatively or in combination: the variation of the vertical position of the upper crown (8) used to attach the pistons, the use of a piston provided with mobile bottom (26) with variable position inside the cylinder of the piston, the construction of a submergible support for the columns (2) provided with compensation chambers or other mechanisms used to change the height.

Figs. 18 and 19 show the combination of a mobile upper crown and a so-called overturned piston. By changing the height of the wave (vq), being the travel of the pistons proportional to it, the assembly composed of float/pistons/upper crown is positioned at different heights along the column (5) that is fixed on the support structure.

The stems (13) are anchored on the float, while the liners or cylinders (14) in upper position are connected to the structure by means of a crown of brackets (8) that can be translated in vertical direction in order to position the bottom (15) in the proximity of the top dead centre of the travel of the plunger (25).

Figures from 20 to 31 show four preferred advantageous executive versions used to control the position of the upper mobile crown (8) of the pistons.

In particular, fig. 20 shows a first executive version that provides for a hydraulic positioner piston (28) inside the column (5), which is connected to the upper crown (8) by means of slots (16) on the column (5) or by means of suitable brackets; the said brackets provided between the positioner piston and the upper mobile crown (8) advantageously act as vertical guide for the mobile crown in order to avoid circular displacements. Figs. 21 , 22, 23 and 24 show an upper crown (8) provided with a rotating ring (17) with internal thread, screwed on toothed bars (18) in vertical position along the column.

Advantageously, the circular motion of the threaded ring is transmitted by a vertical profiled shaft (19) engaged with a tooth wheel (20) that engages with the upper crown (8).

The rotation of the shaft is provided by a gear motor (21 ) installed on the top of the column (5).

In this way, the shaft is driven into rotation and, by means of the tooth wheel, it actuates the rotating ring (17) that, because of its thread, is moved vertically along the column, thus moving the upper crown (8).

Figs. 25, 26, 27, 28 show a preferred alternative executive version used to control the position of the upper mobile crown (8) of the pistons. In particular, this alternative executive version provides for an upper crown (8) with an internally threaded rotating ring (17) that is screwed onto toothed bars (18) in vertical position along the column, as described and illustrated above for figures from 21 to 24.

In this case, the gear motor (21 ) is directly installed on the crown (8) and engaged with the rotating ring (17) by means of the tooth wheel (20). Also in this case, the rotating ring (17) engages the internal thread in the vertical tooth bars (18), thus moving the upper crown (8).

Figs. 29, 30 and 31 show an additional alternative executive version used to control the position of the upper mobile crown (8) of the pistons, which comprises a system composed of four vertical female screws (22) screwed into corresponding passages obtained in the mobile crown (8).

Similarly, the motion is provided by a gear motor (21 ) installed at the top of the column (5) and is transmitted by a tooth belt or chain (23) by means of tooth wheels (20) and idler rolls (24) that also act as tensors for the belt. Figs. 32 and 33 show an executive version according to which the pistons are anchored to the column in the proximity of the bottom from which the stem protrudes, rather than on the side of the ending bottom. According to the said executive version, the pistons (13) are connected to the upper crown (8) near the end of the cylinder that is closer to the stem.

Advantageously, this allows to reduce the emersion of the column, as shown in the drawing with (qc) at a lower height.

In order to improve the resistance of cylinders and the cohesion between the cylinders of the pistons, the liners of the pistons, that is to say the cylinders, are connected by cross-pieces or similar elements to form a network structure that joins the pistons and improves the sturdiness of the assembly.

Figs. 32 and 33 show the height variation (vq) of the crown (8) caused by two waves with different height. Also in this case, movements of the upper crown (8) are provided according to the aforementioned executive versions. Figs. 34 and 35 show the combination of a mobile upper crown and a so-called straight piston.

This solution has the same characteristics as the solution that provides for the combination between a mobile crown and an overturned piston, as described and illustrated above, with the difference that the cylinder (14) of the pistons is connected to the float (6) and the stems (13) are connected to the column (5).

The intake (49) and delivery (48) pipes are obtained inside the stem, being preferably concentric, while the intake (29) and delivery (30) valves are preferably positioned in the thickness of the plunger (25). An alternative advantageous solution provides for the combination of a fixed crown coupled with at least one piston with mobile bottom, as shown in figs. 36 and 37.

As described above, pistons with mobile bottom are basically special pistons that avoid, either completely or in part, the need to move the upper crown vertically.

The constructive peculiarity of the piston is the presence of a mobile bottom (26) inside the cylinder that is positioned in the proximity of the top dead centre of the plunger (25) when sea conditions change.

The bottom is moved by an independent hydraulic circuit that introduces filling oil (27) in the liner (14), thus permitting fixing in position.

Basically, when the presence of a wave with higher size varies the top dead centre of the plunger travel, the consequent increase of the travel of the pistons moves the bottom (26) to a new operating height, and a suitably set maximum pressure valve (42) ejects the filling oil that is recovered in the corresponding circuit.

Oil (27) is pumped again inside the liner to reduce the height of the mobile bottom (26). In this way the volume of the compression chamber is always related with travel and operating height.

Moreover, the application of the valve that is set to discharge the oil from the liner causes the automatic adjustment of the operating height when passing from low to high waves. Because of this process, the system is continuously adapted to the height variation (vq).

From the operative point of view, in this case the total length of the pistons must be increased with respect to the maximum permitted height variation (vq). In fact, to calculate the maximum travel of the piston, the difference in height between the lowest wave point in low tide and the highest wave point in high tide must be measured, in sea storm conditions.

The compressed air is intercepted by means of the stem that is internally provided with two concentric chambers for intake (49) and delivery (48). The intake and delivery valves are obtained in the thickness of the body of the plunger (25). As described above, the liners or cylinders positioned on the float, that is to say straight pistons, are advantageously characterised by easy connection of the piston delivery to the installation.

Figs. 38 and 39 show the combination of a fixed crown coupled with a piston with mobile bottom, i.e. overturned piston, with liners on top and stems attached to the float. This solution offers additional advantages, because the oil mass and the pumping installation do not oppress the float.

The connection of the compressed air at the end of the stem is obtained by means of an extensible pipe that follows the end during the alternate motion.

Figs. 40 and 41 show an especially advantageous combination of a fixed crown associated with a submergible platform or submergible support structure anchored to the sea bottom. In this case, the height variation is obtained by means of a fixed upper crown (8) of the pistons, in which the columns (5) rest on a submerged platform (2), whose immersion height is varied by means of the cables (289 used for anchoring to the bottom. In practical terms, the emersion height of the column with respect to the sea is altered, and not the height of the attachment point of the pistons to the column, thus obtaining advantages similar to the preceding solutions.

Alternatively, a combination between a fixed crown and an internally guided submergible platform is provided, as shown in figs. 42 and 43. Figs. 42 and 43 show a submarine support tower structure (4), on top of which, internally and/or externally to the perimeter formed between the columns of the structure, a submerged body is immersed, at variable heights, used to support the assemblies composed of column/body/pistons.

Also in this case, the use of the mobile crown is advantageously avoided, since the operating height is reached by means of floodable tanks that change the gravitational position, while the presence of the structure eliminates the need for anchoring to the sea bottom.

A similar solution is shown in fig. 44, which illustrates a fixed crown combined with a support structure configured as a submergible extemally- guided platform.

In this case, the platform is external to the tower structure (4) and forms a preferably and advantageously circular platform, where multiple concentric rows of columns (5) can be installed, being combined with the internal platform, meaning that the same tower structure simultaneously support a platform in internal position and a platform in external position.

Fig. 45 shows the diagram of the hydropneumatic circuit according to the present invention. In particular, the figure shows the bottom (15) of the piston (7) where the check valves (29) and (30) for air intake in the piston and for delivery of compressed air towards the pressurization circuit of the tanks (31) and (32) are positioned. A maximum pressure valve (33) is used to discharge the excessive pressure in the tank (34) that operates both as shock-absorber for pressure peaks and as pressure reserve. The safety valve for overpressures (35) is also responsible for sequential filling in case of multiple reserve tanks. They feed the main circuit by means of the same valve (33) when the operating pressures falls within a threshold value in calm sea conditions.

The pistons (7) convert the kinetic energy of the waves into pneumatic pressure that pressurizes the tanks (31 ) and (32) through the directional-control valve (36).

In the phase illustrated in the drawing, tank (31 ) is the feeding tank and tank (32) is the recovery tank.

The valve (36) alternatively directs the air between the two tanks, feeding the tank full of oil and discharging the pressure from the other tank.

The residual pressure in the feeding tank at the end of the cycle, before being completely lost in the atmosphere, is partially recovered by the pilot-operated directional-control valve (40) that feeds the reserve tank (34) up to a suitable value for maximum efficiency of the system.

This valve is controlled by the pressure of the reserve tanks (34) and set to direct the air discharged from the tank at the end of the cycle into the reserve tank, up to a certain pressure value. The correct setting is a balance between the thrust pressure and the pressure necessary to fill the reserve tank. Beyond the threshold value, the effort made to overcome the filling pressure of the reserve tanks sets an excessive weight on the feeding pressure, thus negatively affecting the global efficiency of the circuit.

By giving a thrust to the oil, the pressurised tank (31 ) powers one or more hydraulic motors connected to AC generators.

The directional-control valve (37) is designed to sort out the oil between the motor and the two tanks (31 ) and (32), which alternatively operate according to a different function.

The two directional-control valves (31 ) and (32) operate simultaneously based on the impulse sent according to the level of hydraulic oil contained in the tanks. Advantageously, the following variants or executive specifications are provided to increase the adaptation capability of the circuit to marine variables: the hydraulic motor is a motor of variable cylinder capacity to optimise rotation according to the different pressure values of the circuit. The cylinder capacity varies according to the characteristics of the hydraulic flow. A choker (37) is provided downstream the tanks in order to maintain the pressure at a minimum functional value when the waves are very small. The choker is inversely proportional to the pressure of the circuit and is automatically deactivated beyond specific pressure values.

Other hydraulic motors are connected in parallel to divide the pressure generated in case of rough sea over multiple generators. The rougher the sea, the larger the quantity of produced air and the more the operating hydraulic motors. Sequence valves (39) are installed downstream the directional-control valve (37) to feed the additional motors. The valves open in sequential mode with regard to the different pressures reached by the hydraulic circuit. The circuit pressure is decreased when one of these valves is actuated. This event causes an intervention on the volumetry of the hydraulic motors that must adapt to the flow in order not to reduce the rotations.

According to other advantageous characteristics, a system is provided for energy conservation in pressure reserve tanks fed by the peaks of the main circuit and by the recovery of residual pressure in the feeding tanks (31 ) or (32), when they change operating phase. The reserve capacity is increased by connecting multiple tanks, using the energy of a storm at best. Two systems can be advantageously used to store the energy: pressurizable containers with constant volume and/or special containers with variable internal volume according to the pressure, which must be constant. Fig. 45 shows a first executive version of a tank for compressed air. The tank (34) for compressed air is represented in the diagram of the hydropneumatic circuit.

The reserve can be advantageously composed of a series of tanks (34) fed by the overpressures of the circuit and by the discharge of the pilot- operated valve (40), which recovers the convenient part of the residual pressure in the tank (31 ) or (32) at the end of the cycle.

A connection in sequential mode is advantageously provided between the reserve tanks (34) in order to maintain minimum functional energy for each portion of the total reserve volume. Each tank is fed when the preceding tank has reached a certain filling pressure.

Fig. 46 shows a second executive version of a tank for compressed air, being a tank with constant pressure and variable volume, in particular a cylindrical tank anchored or fixed to the sea bottom. According to this executive version, a series of vertical cylinders (43) closed on top is anchored to the sea bottom and connected in such a way to be pressurized by the main circuit. An expandable air bubble is formed inside the cylinder, whose pressure is counterbalanced by the sea pressure.

The depth of the air bubble directly affects the operating pressure: for example, at 100 m depth the counterpressure is 10 atm.

This type of tanks can be positioned at the base of a submarine support structure and, alternatively or in combination, may be advantageously provided inside the columns of the support structure.

Fig. 47 shows an alternative executive version of a tank with constant pressure and variable volume, as one or more inflatable balloons. In this case a certain quantity of inflatable balloons (51 ) is connected in series at the necessary depth to obtain the desired pressure. The external pressure of the water counterbalances the pressure of the accumulated air, while the elasticity of the membrane that forms the balloon guarantees constant outlet pressure. The variation of the total volume of the reserve does not affect the pressure, being the latter maintained by the external pressure of the sea.

Advantageously, a system is provided to anchor the elastic balloons and/or submerged cylinders at variable heights in order to vary their internal pressure.

According to the present invention, the system of tanks can be used to recover part of the pressure in the tank (31 ) or (32) in the final moment of the powering phase of the hydraulic motor.

In fact, if the circuit operates with a certain pressure P on the surface of the oil of the hydraulic circuit (50), after the phase change between the two tanks, from feeding tank in active phase to recovery tank in passive phase, before being completely discharged into the atmosphere, the residual pressure P of the empty tank is recovered up to a pressure value p < P set for convenience purposes for final efficiency, meaning that the recovered pressure p is limited to such a value that recovery is not too difficult for the main pressure P to overcome the pressure of the reserve where recovery occurs. The recovery of the air discharged by the tank (31 ) or (32) should be started at a low counterpressure height, that is to say with the minimum immersion of the tank, in order to initially receive most of pressure P.

Successively, the reserve is brought at a higher depth in order for the internal pressure to reach the operating pressure. A system of air bubbles, regardless of their collection method, for instance by means of submerged balloons or tanks, is useful, with the possibility of changing the internal pressure of the said balloons or tanks by changing the depth of their position.

Claims

1. Production system of electricity from sea wave energy, characterised by the fact that it comprises:

- at least one support structure to support at least one emerged or emergible column (5), - one float (6) that slides on the said column (5),

- the float (6) being operatively connected to a pneumatic piston (7) for production of compressed air

- the compressed air being, at least partially, conveyed by means of a pneumatic circuit, to at least one first tank (31 ), being the said first tank in active phase, i.e. powering at least one hydraulic motor (38) by means of at least one hydraulic circuit,

- the hydraulic motors being operatively connected to at least one alternator for production of electricity.

2. System according to the preceding claim, characterised by the fact that it provides for at least one second tank (32), being the first (31) and second

(32) tank alternatively in active phase - i.e. feeding oil to the hydraulic motor (38), and in passive phase - i.e. recovering oil from the said hydraulic motor, being the tank in active phase fed by the compressed air and the tank in passive phase maintained at atmospheric pressure until it is filled with oil from the hydraulic motor.

3. System according to one or more of the preceding claims, characterised by the fact that it provides for at least one pneumatic directional-control valve 36) and one hydraulic directional-control valve (37), being the said pneumatic directional-control valve (36) positioned in the pneumatic compressed air circuit of the two tanks, and being the hydraulic directional-control valve (37) connected to the outlet of the hydraulic fluid into the hydraulic motor, in such a way that the hydraulic directional-control valve (37) and the pneumatic directional-control valve (36) are simultaneously actuated by the same impulse for simultaneous switching from the active to the passive phase and vice versa of the two tanks (31 , 32).

4. System according to one or more of the preceding claims, characterised by the fact that it provides for pressurizable tanks (34) for compressed air storage connected to the pneumatic circuit.

5. System according to one or more of the preceding claims, characterised by the fact that the support structure is a support tower structure (1 ) anchored on the sea bottom and/or a submergible platform (2) anchored to the sea bottom by means of cables or chains or similar items (3) and/or is a submergible platform submerged by means of vertical translation of the said platform with respect to at least one tower structure (4) or similar element, being the said tower structure or similar element anchored on the sea bottom.

6. System according to one or more of the preceding claims, characterised by the fact that the support structure supports at least one column (5) on which at least one float (6) slides along a vertical translation direction along the said column when a wave arrives, which is mechanically connected to at least one corresponding piston (7).

7. System according to one or more of the preceding claims, characterised by the fact that the column has a circular or polyhedric section and is provided with sliding guides, such as guides and/or wheels and/or trolleys (11 ) between the column and the float.

8. System according to one or more of the preceding claims, characterised by the fact that the mechanical connection between the pneumatic piston and/or said column and/or said float is obtained by means of upper fixing brackets and/or lower fixing brackets, being the said fixing brackets, especially in case of multiple columns with corresponding floats, arranged in crown configuration, being the so-called lower crown (9) and upper crown (8).

9. System according to one or more of the preceding claims, characterised by the fact that the float preferably has a spheroidal shape with slightly flattened poles, such as ellipsoid or similar shape, being also provided with a cylindrical opening (10) along the vertical axis designed to house the corresponding column, with sliding guides, such as guides and/or wheels and/or trolleys (11 ) provided between column and float.

10. System according to one or more of the preceding claims, characterised by the fact that the pneumatic piston is a so-called straight pneumatic piston, which comprises a part of stem (13) at the free end of the stem of a plunger (25) that slides inside a corresponding cylinder (14) or liner, being the said cylinder (14) in lower position with respect to the stem (13), when the piston is mounted, and the said cylinder being connected to the float by means of the lower crown, the said stem being connected to the upper crown, in which air is taken at the top of the stem (13), that is to say at the free end of the stem, the said stem (13) also comprising a delivery pipe and a plunger (25) that comprises at least one intake valve (29) and one delivery valve (30) of the air.

11. System according to one or more of claims 1 to 9, characterised by the fact that the pneumatic piston is a so-called overturned pneumatic piston, which comprises a stem (13) in lower position with respect to the cylinder (14), when the piston is mounted, being the said stem connected to the float (6) by means of the lower crown (9), the said cylinder (14) being connected to the upper crown (8), in which air is taken at the top of the cylinder (14), providing at least one intake valve (29) and one delivery valve (30) in the thickness of the free end of the said cylinder, that is to say in the bottom of the said cylinder.

12. System according to one or more of claims 10 or 11 , characterised by the fact that the pneumatic piston is a so-called pneumatic piston with mobile bottom, which comprises a stem (13) that slides in a corresponding cylinder (14), the said stem (13) being provided at the end inside the cylinder (14) with a plunger, and the said cylinder being provided at the end opposite the end coupled with the stem (13) with a mobile bottom (26) that slides inside the cylinder, in such a way that the compression chamber between the walls of the cylinder, the mobile bottom (26) and the plunger of the stem (13) is a compression chamber with variable volume, the volume variation being obtained by moving the said mobile bottom (26) closer or further from the plunger.

13. System according to the preceding claim, characterised by the fact that the movement of the mobile bottom closer or farther from the plunger is obtained by filling/emptying the oil in the liner o cylinder (14) between the fixed bottom, the mobile bottom (26) and the walls of the cylinder (14), the said filling/emptying being obtained by means of an oil circuit fed by a pressurized tank and/or a hydraulic shock-absorber (45) that pushes the oil inside the cylinder (14) and recovers it when it is ejected, with a pilot-operated valve (44) being designed to block the oil ejection from the cylinder in order to set the mobile bottom (26) in position during the intake and compression stages of the air.

14. System according to one or more of the preceding claims, characterised by the fact that the upper crown and/or lower crown are constrained by means of a sliding guide (47) and/or provided with spring shock-absorber (46).

15. System according to one or more of the preceding claims, characterised by the fact that it provides for a pneumatic piston as claimed in claim 11 , in which the upper crown (8) moves in vertical direction along the column, being provided with movement means to move the bottom (15) with reference to the top dead centre of the travel of the plunger (25).

16. System according to claim 15, characterised by the fact that the movement means include at least one hydraulic piston (28) positioned inside the column (5) and comprise at least one, preferably multiple slots (16), or openings, on the column, being the hydraulic piston operatively connected to the upper crown (8) to move the upper crown along the column.

17. System according to claim 15, characterised by the fact that the movement means comprise at least one rotating ring (17) connected to the column, the said rotating ring (17) being internally threaded, and at least one or more toothed bars (18) in vertical position along the column, the said ring being designed to engage by screwing/unscrewing to the toothed bars with circular motion, the said circular motion being transmitted by a basically vertical profiled shaft (19) engaged with a tooth wheel (20) hinged on the upper crown (8), with at least one gear motor (21 ) being provided at the top of the column (5) and connected to the profiles shaft by means of the tooth wheel.

18. System according to claim 15, characterised by the fact that the movement means comprise at least one rotating ring (17) connected to the column, the said rotating ring being internally threaded, and at least one or more toothed bars (18) in vertical position along the column, the said ring being designed to engage by screwing/unscrewing to the toothed bars with circular motion, the said circular motion being transmitted by a gear motor (21) joined to the upper crown, the gear motor (8) being engaged with the rotating ring (17) by means of the tooth wheel (20).

19. System according to claim 15, characterised by the fact that the movement means comprise at least one, preferably multiple, in particular four vertical female screws (22) engaged on the upper crown (8), being the said female screws designed to rotate on their axis in order to move the upper crown vertically along the column, the rotation of the female screws being provided by a gear motor (21 ) installed on the top of the column (5), the gear motor being connected to the said female screws by means of a flexible connection, such as a toothed belt and/or a chain (23), the flexible connection means being designed to engage with at least one tooth wheel (20) provided on the top of each female screw, with corresponding idler rolls (24) being provided to return and provide tension to the flexible connection means.

20. System according to one or more of the preceding claims, characterised by the fact that the cylinders of the pistons are connected to the upper crown in the proximity of the end of the cylinder used for coupling the cylinder with the stem, being the said cylinders connected by means of connection elements, such as cross-pieces or similar elements to form a network structure.

21. System according to one or more of the preceding claims, characterised by the fact that it comprises a pneumatic piston as claimed in claim 10, in which the piston (7) has the corresponding cylinder (14) connected to the float by means of the lower crown and the corresponding stem (13) connected to the said column (5) by means of the upper crown, being the intake (49) and delivery (48) pipes obtained inside the stem, in particular being concentric, with the intake (29) and delivery (30) valves being positioned in the thickness of the plunger (25).

22. System according to claim 14, characterised by the fact that the upper crown is fixed with respect to the column and multiple hydraulic pistons are provided in combination, according to claims 11 to 13.

23. System according to one or more of the preceding claims, characterised by the fact that the pressurizable tanks for compressed air storage connected to the pneumatic circuit are pressurizable tanks with constant volume (34) and/or containers with constant pressure and variable volume.

24. System according to one or more of the preceding claims, characterised by the fact that the pressurizable containers with constant volume are cylinders or similar vertical elements (43) closed on top and connected to the said pneumatic circuit in such a way that an expandable air bubble is formed inside the cylinder, the said vertical cylinders (43) being anchored to the sea bottom and/or inside the columns (5) or support structure.

25. System according to one or more of the preceding claims, characterised by the fact that the pressurizable tanks with constant pressure are inflatable balloons.

26. System according to one or more of the preceding claims, characterised by the fact that the pressurizable tanks are fixed or movable at variable depth in order to change their internal pressure.