Field of application of the invention

The present invention relates to exploitation of alternative forms of energy and, in particular, to a plant for the production of electrical energy in a coastal area, fed by diversified sources of renewable energy. The invention concerns exploitation of wave motion of any intensity, whether at sea or on a lake, even if the greatest opportunities of using this energy are found at the sea coast. Tidal action however is of no particular interest and for this reason the plant for produc- tion of electrical energy can be located in coastal regions where tidal action is limited.

Review of the known art

In the most industrialized countries, electricity is produced at power stations that to a great extent are still dependent on fossil fuels, by their very nature ex- haustible and polluting, not to mention nuclear with its attendant risks and problems over the elimination of radioactive waste. For some time past serious attempts have been made to develop the use of renewable sources of non- polluting energy such as water power, ocean wave motion, tides, wind, solar radiation.

The Italian patent No. 0001368431 filed on 4.5.2006 entitled: "Mechanical project for exploiting wave motion to produce electrical energy" describes "a system comprising a central flywheel (cardan) connected by a pulley to the shaft of a dynamo". The flywheel is fixed to a shaft hinged at its two ends to a support by two respective anti-reverse bearings. Two cogwheels are fitted onto the centre of the shaft by two further one-way rotating ball bearings, the one-way joints of the "freewheel" type. A float is joined to the end of a first chain wound from the right onto the first cogwheel, a first counterweight being joined to the other end of the chain. The same float is joined to the end of another chain wound from the left onto the second cogwheel, a second counterweight being joined to the other end of the chain. With this arrangement the flywheel rotates continuously during both.the rise and fall of the float.

The mechanical design described above needs two counterweights to transmit power to the shaft, their weight necessarily being in proportion to the peak of electrical power to be generated. This involves the use of an even heavier float to avoid of coming out from the water at the end of the rising stage, and to raise the other counterweight during its descent. Shape and materials being equal compared with those of a float without counterweights, the fact that the float is heavier means that there is less possibility of fully exploiting hydrostatic thrust, the height of the part above water being lower. For these reasons, although this mechanical design can deal with small waves, it would be clumsy and bulky should it be necessary to increase the number of flywheels and floats to provide enough power for a plant that produces electrical energy.

Today, conversion of energy from wind turbines, solar panels and marine wave motion into electric power is a recognized reality even if a combined exploitation of these sources, by their very nature discontinuous, raises problems of how to achieve a regular supply of energy. Considering conversion of wave motion or tidal action alone, the most successful examples so far realized involve the use of large buoys or of vertical tubes of a large diameter to exploit hydrostatic pressure to the maximum. Large plants have already been set up in coastal areas where wave motion is usually high and/or where there is marked tidal action, even in the open sea where interference with tourism is unlikely.

Many people of ecological convictions would like to be able to use an electric car to reach the seaside, and be able to park and recharge their batteries. At such places there is often no electricity supply but, even if there were, owners of electric cars would prefer not to use it if it came from a polluting source and would prefer energy from a renewable source that could serve this purpose, any surplus to be available for sale to the electricity company.

An 'ecological' solution to this problem appears to coincide with present trends by automobile makers who, fearing an excessive exploitation of resources of fossil fuels, have begun producing non-polluting electric vehicles, even if inevitably of limited charge, mileage autonomy and acceleration. While for vehicles of the traditional kind there are plenty of service stations along main roads, the same is not true when it comes to recharging the accumulators that feed the engines of recently introduced electric cars. When electric cars are more widely used there will be more stations to service them but meanwhile the risk of exhausting a car battery during its journey is very real.

Today it is hard to foresee if and when electric-accumulator technology can overcome the intrinsically limited concentration of charge as yet unable to com- pare with the chemical energy stored in an equivalent mass of petrol or diesel oil. The fact still remains that paying a visit to a seaside area with clean air at some distance from main highways presents real problems of autonomy for electric vehicles, especially on their homeward journeys

Purposes of the invention

The main purpose of the present invention is therefore to suggest a method of producing electrical energy in a synergic combination of diversified sources of renewable energy all present at the same place.

Another purpose of the present invention is to suggest a system of exploiting energy from wave motion that is both mechanically simple and effective in achieving its object.

A further purpose still is to indicate a manner for local exploitation of the electrical energy produced.

Summary of the invention

To achieve these purposes, subject of the present invention is a plant for pro- duction of electrical energy from local sources of renewable energy, including: - means of flotation immersed in an expanse of water subject to wave motion, connected to activating means of a drive shaft coupled to a first electric gen- erator, the activating means including at least one one-way rotation joint, hereinafter called an anti-reverse joint:

characterized in that it also includes:

- a wharf constrained to the bottom of the expanse of water at a fixed height from the bottom to support said means of flotation consisting of at least one first row of floats, and for each float the activating means including:

- an arm joined to said float;

- a second shaft supported by the wharf and rotationally engaged by said arm;

- a 90 degree gear drive engaged by said second shaft and in its turn engaging said drive shaft, hereinafter called a longitudinal shaft, and said degree gear drive being in series with said anti-reverse joint to couple said arm to said drive shaft (46) only when the arm is able to transfer the active power created by hydrodynamic thrust exerted in sequence on the floats by a coming wave (WN),

- a second electric generator operated by wind turbines;

- a third electric generator fed by photovoltaic panels;

- interfacing means comprising means for converting the electric power provided intermittently by each electric generator into an equivalent direct cur- rent electric power at a same DC voltage across an electric line directed towards the charge, as described in claim 1.

Further characteristics of the present invention considered innovative are described in the dependent claims.

The 90 degree transmission plays an important part in utilization of wave mo- tion, known to move from the open sea towards the shore, because the length of a longitudinal structure fitted with floats, such as that of the wharf of the plant described in claim 1 , can be kept as short as possible and placed perpendicular to the coastline.

In one example of its execution the solar panels are placed on the roof of a cor- ridor giving access to the wharf extending along part of its length. The panels are arranged in parallel rows, inclined with opposite angles to maximize the power of solar radiation throughout the day. The wharf is a structure with two bottom levels, the upper one accessible by tourists and the lower one housing mechanical and electrical equipment. The length of the wharf, the number, shape and size of the floats can be decided according to the type of wave motion and to how much electrical power is to be produced from it, to the part cov- ered by solar panels and to how much power they are required to produce. The minimum number of floats in each row must in any case permit uniform rotation of the shaft of the generator of electricity even if rotation impressed by each one is intermittent. Uniform rotation is a result of each float being raised by the incoming wave with, a slight delay compared with the preceding one, and with this delay will provide its own angular contribution to rotation; as a consequence, during the inactive downward stage of float movement, there will in any case be floats farther along the row whose movement will be in the upward stage.

In one preferred configuration the axis of rotation of the hub that carries the blades of the wind turbines is kept parallel to the longitudinal axis of the stretch of wharf occupied by the floats so as to catch the wind from the sea that creates the waves most useful for correct activation of the floats; this is not a limit for the invention as it is possible rotate the nacelle which bears the blades and includes the dynamo, so as to follow the variable direction of the wind.

The function of the wharf therefore extends well beyond its section in the water integrating the photovoltaic function in a single synergic structure with the preferred disposition of the wind turbine blades.

In one example of its realization, the drive shaft is coupled to the shaft of the first generator by an overgear.

According to one aspect of the invention, the drive shaft lies along the wharf for about its entire length, while said second shafts lie transversally to it.

In one example of its execution, the longitudinal shaft consists of several sections coupled together by joints able to offset reciprocal misalignments and variations in length when there is a change of temperature. Cardan joints can serve for both uses but if drive shafts are very long and if temperature changes are considerable, additional expansion joints could be fitted in series to some of the cardan joints. In one example of its execution, said first row of floats is placed at one side of the wharf outside it, and the arm of each float is inclined outwards to create a space between said first row and the side of the wharf to make room for a second row of floats, each one in the second row being offset, preferably equally spaced, in relation to the two following floats in the first row.

In one example of its execution one or more further rows of floats can be equipped in the free space under the bottom of the wharf.

In one example of its execution, unless the wharf has also to be used for anchoring pleasure boats, the shape of floats at one side and, possibly under the bottom, up to half the width of the wharf, and related mechanical equipment, is equally reflected on the other side.

In one example of its execution comprising more longitudinal shafts, each shaft is coupled to the shaft of a respective electrical generator.

In one example of its execution comprising more longitudinal shafts, each shaft is coupled to the shaft of a common electrical generator, for example by means of belts and pulleys or equivalent kinematic mechanisms.

In one example of its execution a probe float is mounted on the front of the wharf coupled to positional sensors fixed to the wharf and, optionally, fitted with an accelerometer. It is of advantage, therefore, if this float is suited to sensing the presence of particularly high waves and can signal this situation to the electronic controls, to activate joints for coupling the shaft of at least one supplementary dynamo to the shaft of the dynamo then functioning, for example by friction clutches.

Before going on to explain the next three examples of execution in the kine- matic series consisting of the anti-reverse joint and transmission at 90 degrees, it must be stated that the one-way effect impressed in rotating the longitudinal shaft has no reference to the order in which these components come in the series. Once the configuration of the kinematic chain for a float has been established, the direction of rotation of the longitudinal shaft is also determined and will be the same for all the kinematic chains of the remaining floats. The anti- reverse joint is a well-known device in mechanical processes, as a bearing fitted with ramps for rollers or ball bearings reciprocally engaging the two crowns, or as a reel with a spring catch (pawl).

In one example of its execution the anti-reverse joint connects the respective transverse shaft to one of the two elements of the transmission at 90 degrees, causing it to rotate.

In one example of its execution the anti-reverse joint connects one of the two elements of the transmission at 90 degrees to said longitudinal shaft, causing it to rotate.

In one example of its execution the anti-reverse joint connects the arm of the respective float to the transverse shaft causing it to rotate.

In one example of its execution each transmission at 90 degrees comprises a pair of bevel gears the first of which engages the transversal shaft while the second engages the longitudinal shaft.

In one example of execution, the revolutions made by said pair of bevel gears are the same.

In another example of its execution, said pair of bevel gears is an overgear of the longitudinal shaft.

In one example of its execution, both the transmission at 90 degrees of one row or of several parallel rows of floats external to the wharf, and second 90 de- grees transmissions of an adjacent row of floats under the wharf, are coupled to a single longitudinal shaft, the first and second transmissions being so configured to impress a rotation of agreed direction onto the longitudinal shaft.

The decision on where to build the plant is of particular importance as it must be a place where the three sources of renewable energy are available in sufficient quantity.

Disposition of the floats in relation to the coast is best decided according to the main direction of wave movement: a) where wave movement is prevailingly transversal to the shore a greater length of the wharf orthogonal to the coastline will be occupied by the floats; b) where wave movement is prevailingly parallel to the shore a greater length of the wharf parallel to the coastline will be occupied by the floats; c) where wave movement alternates between transversal and parallel to the shore, a first section of the wharf will be occupied by floats lying transversal to the shore and a second section of equal length will be occupied by floats parallel to it; d) where the direction of wave movement varies and there is no main direction of flow, the wharf will lie obliquely to the coastline. When, in all its variability, wave motion is directed onto the front of the wharf, the foremost floats receive hydraulic thrust before those behind, but the floats being coupled to the longitudinal shaft by the 'freewheel' mechanism prevents those behind from being passively carried along above the surface of the water by rotation of the longitudinal shaft as, being still inactive, they are neutral in relation to the shaft's rotation. It should also be noted that the 'freewheel' mecha- nism means that the angular speed reached by said 90 degree transmission is equal to or greater than the angular speed of the longitudinal shaft when fully operative, so effectively transmitting its contribution of mechanical power to the shaft. Each inactive float, not yet transferring dynamic power to the longitudinal shaft and therefore accelerated to the maximum by upward thrust from the com- ing wave, in fact fulfils this condition impressing an angular speed on the 90 degree transmission initially greater than the steady one of the longitudinal shaft, whose rotation is slowed by transfer of power to the rotor of the electrical generator as well as by losses due to friction in the supporting bearings and in the joints over a long distance. It follows that the longitudinal shaft acts as collector of contributions of power independently from each single float.

It would be advantageous to have accumulator-battery recharging facilities for electric vehicles stationed near the plant; these to include several charging slots each fitted with an electric socket for DC current at a voltage only slightly higher than rated voltage of the batteries.

From both functional and aesthetic standpoints, the mast carrying the blades of the wind turbine and related generator might preferably be situated in the middle of an open space near the entry to the corridor leading to the wharf, accessible from the road network with branches to the recharging station and to a car park for electric vehicles.

Concerning realization of the above interfacing means among outputs of the various generators of electricity and the charge, a problem arises over bringing output voltages at the generators to a single level of voltage at the charge. The problem with the generators arises because the respective rated output voltages are usually different as are trends in power during the 24 hours. A DC charge consisting of the electric car batteries, and an AC charge at a different rated voltage consisting of the charge present in the electricity mains at low voltage, must also be supplied when surplus electric power is transferred. The individual photovoltaic cell generates low-voltage DC but several cells can be connected in series to reach the required voltage. The wind turbine blades move the rotor of a dynamo or else of an alternator, and the same applies to the shaft of each electrical generator used in exploiting wave motion. Within certain operative limits where renewable sources of energy are concerned, the angular speed of such electric machines can be mechanically stabilized by various known methods, consequently stabilizing the nominal value of voltage generated. The AC voltage generated at the terminals of an alternator can easily be converted to the desired level by a transformer and, if necessary, be rectified and levelled. For the wind and wave-motion component dynamos could also be chosen that generate the DC voltage required by the user although this somewhat inflexible and costly approach is inadvisable. Lastly, it should be noted that the rated voltage tends to fall with a higher charge so that, within certain limits of absorption, voltage on the charge must be stabilized.

In one embodiment the interfacing means implemented at the plant of the present invention solve the problems described above, including first converters that convert the power generated by respective generators into a corresponding single-voltage power for all the first converters applicable in parallel to the charge, each electric generator being therefore able to supply at a common charge its own contribution of power when available.

According to one aspect of the invention the first converters are DC/DC converters.

According to another aspect of the invention the first converters are AC/DC converters.

In one embodiment the interfacing means also include second converters of electric power converted in DC by said first converters with outputs in parallel, into AC electric power at the low-voltage domestic network frequency and at only a slightly higher voltage so that the power surplus produced at the plant can be transferred to the electricity mains.

An inverter is also provided at the DC output of the interface able to supply mo- nophasic alternating current at a voltage only slightly higher than those of the low-voltage network (220 V, 50 Hz), and at the same frequency, that goes automatically into the electricity mains as soon as there is a surplus of power from the plant extra to that required by the batteries being recharged.

Advantages of the invention

Integration at a single plant of several generators fed by different sources of re- newable energy would provide a more uniform supply of electric power over a period of time compared with that possible if the three sources were exploited singly. For example, on a fine day with a calm sea and little wind the photovoltaic source would give a better result while wind and wave-motion sources would produce the minimum. On cloudy days with rough seas and strong gusts of wind, wave-motion and wind sources would be more productive and solar panels at the minimum. The control system will only direct those really productive sources onto the charge, cutting off the unproductive sources to prevent their becoming inactive users of power. A very different result would be obtained if management did not integrate the various sources with a generator of each source feeding the charge assigned to it. Clearly such a charge cannot be fed when the respective sources are unproductive, while this does not happen in the plant here described. The synergy that the invention can realize among the different means that cooperate in exploitation of the three renewable sources is thus clear.

An intelligent management of the data provided by the probe float enables the control system, typically operated by a microprocessor, to increase productivity of the active sources during windy days and with rough seas, coupling the shaft of further dynamos to that of the dynamo in use, for example with friction clutches.

The control system is preferably fitted with a robot for cleaning the photovoltaic panels and with an atmospheric detector for activating it to avoid any lessening of productivity by the photovoltaic installation. Limited to the mechanical part of the wharf, activation of a long drive shaft constrained to a plurality of pairs of bevel gears by respective anti-reverse bearings operated by transversal shafts made to rotate step-by-step by the arms of respective floats, appears as a highly compact mechanical solution able to favour wave motion in extracting all the power possible from it on the long side of the wharf. Due to the considerable length of wharf occupied by the floats, exploitation of their upward stage only is in no way disadvantageous for the reasons explained above; rather does it represent a considerable simplification compared with the known art referred to. The chains and counterweights in fact be- come superfluous, being in any case noisy and difficult to manage over long kinematic distances, as is any other hypothetical attempt to burden the mechanical part for the sole purpose of exploiting the downward stage of the floats which, for the reasons given cannot significantly increase power at the drive shaft, unless it is to increase the weight of the float though at the same time making it more bulky and therefore less suitable for use on a wharf. The fact of having placed the entire mechanical part in the double bottom of the wharf protects it from bad weather and from the corrosive effect of salt, facilitating the periodical greasing of bearings and gears.

The plant of this invention is a new and entirely ecologically sustainable struc- ture of a pleasing environmental impact to the point where the wharf can easily become a tourist attraction housing shops, refreshments, seating and other amenities. The roof of the recharging building can be fitted out for visitors as a panoramic viewpoint. In the uppermost part of the wind tower, at a certain distance from the nacelle including the rotor, a fully soundproofed and wide glazing room can be foreseen, which it can be reached by means of lift or spiral staircase for enjoy a panoramic view. From the panoramic room one can be access to a external gallery, obviously only when blades are inactive.

The wharf can be designed in different ways, such as a port for boats or a pier. Still in the field of ecology, the electricity produced can be used in the surround- ing area to light tourist villages, holiday camps, drive-ins, amusement parks, or to supply a plant for the production of hydrogen considered as being the fuel of the future. Short description of the figures

Further purposes and advantages of the present invention will be clear from the following detailed description and from the attached drawings given purely for explanatory reasons and in no way limitative, wherein:

Figure 1 is a plan view of how the plant for production of electric energy in a coastal region would appear according to the present invention, showing the wharf orthogonal to the coastline.

Figure 1A shows a detail of the end section near the front of the wharf in Figure 1.

Figure 1 B is an enlargement of Figure 1A.

Figure 2 is a perspective view of the section of the wharf in Figure 1 A.

Figure 3 is a side view of a model of the plant in Figure 1 where a cross section of the ground is also shown.

Figure 4 is a front view of the plant in Figure 1 , including the cross section of the ground.

Figure 4A is an enlarged detail of the float on the left in Figure 4.

Figure 5 differs from the view in Figure 1 showing a different design for the wharf.

Figure 6 is a diagrammatic view of a repetitive section of the mechanism that joins the floats housed in the double bottom of the wharf in Figure 1. In the left- hand part of the figure in correspondence of the upper and lower corners, two details referred to the reciprocal rotations of orthogonally coupled shafts on the respective sides of the wharf, are shown in perspective.

Figures 6A, 6B, 6C are enlarged details taken from Figure 6.

Figure 7 is a block diagram of the electrical part of the plant in Figure 1.

Detailed description of some preferred ways to realize the invention

In the following description identical elements that appear in different figures may be marked with the same symbols.

Figure 1 shows a plant 1 seen from above, situated partly on the mainland 2 and partly on the sea 3 with a long wharf 4 orthogonal to the shore 5. This latter divides the length of the wharf 4 in a first section where the wharf stands on land, about 40% of its full length, and in the remainder where the wharf is raised above water level. The plant 1 is accessible from the main road 6 from where a car park 8 can be reached and a station opposite 9 where the parked electric cars can have their batteries recharged, ending in an open space 7 in front of the wharf 4. An wind tower 10 stands in the centre of the open space 7 that communicates with the base of the wharf 4 on land. A roof of solar panels 11 extends from the base of the wharf on land 2 to about 60% of its total length and therefore onto the part in the water. From the rounded front 12 of the wharf 4 four rows of floats 13 depart longitudinally towards the base of the wharf, two offset rows per side, to about 48% of the length of the wharf. The wharf 4 is a structure with a double bottom that rests on piles driven into the sea floor. The section of the wharf on land partly rests on a strong base of reinforced concrete 14 in the ground. This part includes a large room used as a power station and operations room containing dynamo, transformers, inverter, relays, control panel, control system, communication equipment and everything else needed for running the plant 1 to ensure that the best possible use is made of the current produced. The mechanical part, to be described below, is housed' in the double bottom of the part of the wharf under water. DC electric cables 15 and 16 leave from the operations room respectively directed towards the car park 8 and recharging station 9, and an AC cable 17 directed to a cabin 18 for connec- tion to the electricity mains 19.

Figure 1A shows the end of the wharf 4 in Figure 1 at the front 12 and a short length preceding it, showing how the floats are lifted by the incoming wave according to the direction of arrow WN. To simplify the drawing the probe float has been omitted. Figure 1 B is only a partial enlargement. Referring to both fig- ures, the view from above shows the two offset rows of floats 13 on each long side of the wharf 4. Referring for simplicity only to the rows of floats shown farther down in the figure, a first row 21 of floats 13 is farther away from the outer side of the wharf 4 compared with a second row 22 whose floats 13 are across the side of wharf 4 between two floats of row 21. All the floats are mechanically connected to the sides of the wharf by pivoting arms one end of which is joined to its own float and the other end articulated to a rigid support with the wharf. More precisely, the floats 13 in the outer row 21 are held tightly by a central ring 26 rigidly joined to an arm 25 inclined towards the outside of the wharf 4 and ending with a length 25a parallel to the side of the wharf. Through the end of length 25a is a hole through which passes a shaft 27 transversal to the longitudinal direction of the wharf 4 to which length 25a, and therefore arm 25, is rig- idly joined. The contiguous float 13 belonging to the inner row 22, is joined to an arm 28 by a tightening ring 29. Unlike arm 25, arm 29 lies parallel to the side of wharf 4 along its full length, this one too having a hole at its end through which passes a transversal shaft 30 and to which it is rigidly joined.

The perspective view in Figure 2 clearly shows the shape of the arms and their position in the two offset rows of external floats. The figure also shows two rows of piers 34 to support the wharf 4 at a level above the water that allows room for the floats underneath (see Figure 4). The considerable depth of the surround 35 indicates the presence of a double bottom to house the mechanical parts. A balustrade 36 encircles the wharf on whose upper surface there are benches and roofed refreshment kiosks 37 with glass walls. It will also be seen that arm 25 of float 3 in the outer row presents a section 25b perpendicular to the fastening ring 26.

Better seen in Figure 3 are the respective lengths of the sections of the wharf 4 over the water 3, on land 2 and at the shoreline 5 that moves back and forth at high and low tide. The piers 34 are well grounded in the sea floor and continue on land in the area of tidal variability. The section on land stands on a strong wall 14 where the dynamos and control system are housed. The base of the wharf 4 on dry land 2 starts from the open space 7 on which stands the wind tower 10. Beyond the space 7 a roofed corridor 11a leads to the wharf 4 with rows of solar panels 11 installed on its roof.

The front view in Figure 4 better shows the arrangement of floats 13 seen in the four longitudinal rows in Figure 1A, plus two rows 40, 41 underneath the wharf 4. Row 40 shares a longitudinal shaft with the outer rows 21 , 22; in the same way row 41 shares the longitudinal shaft with the outer rows 23, 24. Also to note is the wind tower 10 with a horizontal rotor at its summit to carry the three blades 10a, placed to catch the wind from the sea, the same wind that creates the waves to activate the floats 13. Figure 4 A clearly shows the outward inclination of arm 25 fixed to float 13 in the outer row.

The plan view in Figure 5 is an oblique configuration of the wharf 4 in respect of shoreline 5. The smaller angle subtended with the shoreline 5 is from the side of the recharging station 9, but the symmetrical configuration is equivalent, the choice between the two configurations depending on the predominant direction of the wind observed in the long time, and consequently on the direction of the wave motion. As it can be noticed in the figure, even the blades 10a of the rotor carried by wind tower 10 are provisory rotated of the same angle of the wharf to better intercept the wind.

Figure 6 shows a repetitive section of the mechanical part of the wharf 4 housed in its double bottom. The figure is a view from the bottom as if the lower part had ideally been removed. These mechanisms are applied to the floats as illustrated in Figure 1A where they are raised by the incoming wave in the di- rection WN. As the figure shows, the mechanisms include two drive shafts 46 and 60 lying longitudinally close to the sides of the wharf 4, supported by respective steel bases of type 47 and 61 constrained to the frame TL of the structure by radial bearings 48, 62. Shafts 46, 60 consist of a sequence of sections 46a, 60a joined by cardan joints 49, 63 that support the deformation of frame TL due to its length, at the same time absorbing the differences in length of the various sections caused by changes in temperature. The three rows of floats 21 , 22, 40 are constrained to shaft 46 and the three rows of floats 23, 24, 41 to shaft 60. The number of floats in the outer rows 21 , 22 and 23, 24 are the same while rows 40, 41 underneath the wharf 4 have double the number of floats, more or less aligned with those in the two outer rows. This configuration makes for better exploitation of wave motion as the floats in the row under the wharf and the corresponding ones in the outer rows simultaneously receive the impact from the front of the wave. This arrangement is repeated in exactly the same way for the whole section of the wharf equipped with floats. In greater detail: external to the side of the wharf 4 on the side of shaft 46, the row of floats 21 , lying outermost in relation to the side of the wharf, is represented by float 21a, row 22, also an outer row, is represented by float 22a and the row 40 under the wharf on the opposite side in relation to shaft 46, is represented by two floats 40a and 40b. Similarly, external to the side of wharf 4, on the side of shaft 60, the row of outer floats 23 is represented by float 23a, the other outer row 24 is represented by float 24a while row 41 , under the wharf on the side opposite shaft 60, is represented by floats 41a and 41 b. The arm of each float is joined to a first end of its own shaft type 27, 30 orthogonal to the respective longitudinal shaft 46, 60 and therefore transversal to the wharf 4. Steel supports including ball bearings, to sustain transversal shafts type 27, 30, are fixed to the frame TL. These supports, in opposing pairs on the two longitudinal sides of the wharf, one spaced from the other by more than the length of the float arms to allow them to make a complete rotation, are indicated thus: supports 50, 51 to sustain transversal shafts 50a, 51a operated by floats respectively 21a and 22a; supports 52, 53 to sustain transversal shafts 52a, 53a operated by floats respectively 40a and 40b by their own arms 42a and 42b; supports 64, 65 to sus- tain transversal shafts 64a, 65a operated by floats respectively 23a and 24a by arms 23b and 24b; supports 66, 67 to sustain transversal shafts 66a, 67a, operated by floats respectively 41a and 41b, by their own arms 43a and 43b. Each transversal shaft is joined to its own longitudinal shaft 46, 60 by a pair of bevel gears, of which a first gear is engaged in one-way rotation by the second end of the transversal arm while the second gear is fixed to the longitudinal shaft. The transversal shafts activated by floats lying on opposite sides in relation to the longitudinal shaft are misaligned to allow coupling at 90°. The lesser misalignment can be remedied by placing the two bevel gears of the pairs of bevel gears one opposite the other on the longitudinal shaft. Bevel gears en- gaged by the transversal arms include a one-way clutch bearing, of some known type, also called anti-reverse, keyed to its own transversal shaft.

The congruency of direction of rotation impressed by all the pairs of bevel gears on the longitudinal shaft is found by mounting all the anti-reverse bearings in the same direction. The details shown in the left-hand top and bottom corners of figure 6, show the directions of rotation of the involved shafts by means of curve arrows. The depicted details are prospective views of the respective sides of the wharf as seen by observers external to the wharf who see along the di- rection of an axial arrow. Rotation of the longitudinal shaft is made possible by keying the anti-reverse bearings straight into the longitudinal shaft and coupling them to a gear of the respective pairs of bevel gears. The same operation can also be obtained by keying each anti-reverse bearing at the end of its transversal shaft operated by the arm of the float; the direction of the anti-reverse bearing will be the opposite to that of the preceding configuration and the float arm will have a seat that engages the external rim of the anti-reverse bearing.

To explain it in greater detail, the anti-reverse joints 54a, 56a coupled to respective gears of the pairs of bevel gears 54, 56 are keyed to respective transversal shafts 50a, 51 a; the anti-reverse joints 55a, 57a coupled to respective pairs of bevel gears 55, 57 are keyed to respective transversal shafts 52a, 53a; the anti- reverse joints 68a, 70a coupled to respective gears of pairs of bevel gears 68, 70 are keyed to respective transversal shafts 64a, 65a; the anti-reverse joints 69a, 71a coupled to respective gears of pairs of bevel gears 69, 71 are keyed to respective transversal shafts 66a, 67a.

Figure 6A shows in detail the pairs of bevel gears 54, 55 that engage the longitudinal shaft 46 in one-way rotation, and are in turn engaged by the transversal shafts 50a, 52a. It will be seen from the figure that on each gear 80, 81 of the pair of bevel gear 54, and on each gear 90, 91 of the pair of bevel gear 55, there is a cylindrical extension for passage of the shaft in one piece with the side of the ring gear on the side where the diameter is greater; these extensions have been numbered 82, 84, 92, 94 for bevel gears 80, 81 , 90, 91. Bevel gears 80 and 90 are placed across the longitudinal shaft 46 with their faces of a smaller diameter one opposite the other at a reciprocal distance greater than the greater diameter; these gears are fixed to the longitudinal shaft 46 each by its own screw 83, 93 that pass through the wall of cylindrical extensions 82, 92 and screw into threaded holes made for them in the longitudinal shaft 46. At the end of the transversal shaft 50a opposite the end constrained to the arm of float 2 a, an anti-reverse bearing 54a is keyed by means of a tongue 88. Inside the cylindrical extension 84 to bevel gear 81 is the anti-reverse bearing 54a fixed to its outer rim by two screws 86, 87. Similarly, the anti-reverse bearing 55a is keyed by a tongue 98 to the end of the transversal shaft 52a opposite the end constrained to the arm of float 40a. The cylindrical extension 94 to bevel gear 91 includes within it the anti-reverse bearing 55a to whose external rim it is fixed by two screws 66, 97. The arrows indicate the anti-clockwise direction of rotation of bevel gears 81 and 91 made possible by their respective anti-reverse bearings 54a, 55a, a direction converted to clockwise by the respective bevel gears 80 and 90 fixed the longitudinal shaft 46, causing both to rotate clockwise.

Figure 6B shows a section of the support 50 along a plane parallel to the bottom of the wharf .4 passing through the axis of transversal shaft 50a, showing the ball bearing 105 crossed by shaft 50a and kept in its seat by a flange 106 screwed to the wall of the support 50.

Figure 6C shows the rigid connection between the transversal shaft 50a and the upper end 25a of arm 25, seen from above in the horizontal position of arm 25. As shown in figure 6C, a hole 99 is made in the arm 25a through which passes the end of shaft 50a, said end being constrained against the wall of arm 25a by two brackets 100 and 101 and by bolts 102, 103, 104. The two brackets 100, 101 are fixed to the wall 25a on opposite sides of arm 50a by screws 102, 103 and nuts. Brackets 100 and 101 contain cylindrical grooves to receive the arm 25a. Screw 104 crosses through the wall of bracket 100, then through a hole present in transversal shaft 50a and through the wall of bracket 101 to which it is fixed by its nut. This type of rigid connection is obviously only one of those possible.

Figure 7 is a block diagram of the electrical system in the plant 1 in Figure 1 comprising interfacing means between the generators and the charge. The con- vention here adopted uses dark arrows to indicate the current generated and consumed, and therefore of a certain power, and light arrows to indicate the signals without power referred to the signalling. The blocks drawn with continuous lines are physically included in the power station housed in the underground part of the wharf 4, while those drawn with dotted lines are not. The + and - indicate the polarity of DC voltage; one of the two poles can be grounded. Figure 7 shows a photovoltaic generator 201 that on receiving solar radiation generates E1 voltage at the DC output terminals. Generator 201 is connected upstream to a DC/DC converter 202 that generates constant E0 voltage applied to a DC electric line 203. A dynamo 204 generates E2 DC voltage at the output terminals when activated by the blades 10a of the wind turbine generator 10. The dynamo 204 is connected upstream to a DC/DC converter 205 that gener- ates constant E0 voltage applied to an electric line 203. A dynamo 206 generates E3 voltage when operated by the mechanism under the wharf 4; it is connected upstream to a DC/DC converter 207 that generates constant E0 voltage across the electric line 203. Block 206 ideally groups the two dynamos connected to longitudinal shafts 46 and 60. Block 207 ideally includes another DC/DC converter downstream of the dynamo not shown. Dynamo 206 can, if needed, be reinforced by an auxiliary 208, this too activated by the mechanics under the wharf and this too generating E3 voltage. Dynamo 208 is connected upstream to a DC/DC converter 209 that generates constant E0 voltage. The DC/DC converter 209 is connected in parallel to electric line 203 by the two con- tacts of a relay 210. Block 208 ideally groups the two dynamos connected to longitudinal shafts 46 and 60. Block 209 ideally includes another DC/DC converter downstream of the dynamo not shown.

DC users are connected in parallel to electric line 203, these users being the accumulator batteries, shown diagrammatically by respective conductance 212, belonging to the electric vehicles that use a recharging station 211 adjacent to the plant. Line DC 203 feeds an inverter 213 that generates monophasic alternating current (AG) at the output terminals at 50 Hz of rated value 230 V (here indicated by Eal). These terminals are connected in parallel to the low voltage electric line 215 to put in the surplus power produced, and are connected in parallel to a local line 214 that serves local consumers 216, here diagrammatically indicated by a resistance 217. A pad accumulator 218, here diagrammatically indicated by conductance 219, has greater capacity compared with that of single batteries 212 and rated voltage of a compatible value. By means of the two contacts of a relay 220 the accumulator 218 can be connected in parallel to the electric line DC 203. The accumulator can function as a charge, when it accumulates energy, or as a generator when returning it. Lastly, the electric line DC 203 is connected to a microprocessor electronic controller 230 with its own two-way bus 231 to which the sensors and remote actuators in the various devices can be connected when they ask for it, as can the instruments for measuring current and voltage at the outputs of generators and on the charge. One of these devices is the probe float 232 as regards the sensor of position and, if present, the sensor of acceleration whose signalling will be used by the control system 230 to operate an actuator 233 whose task is that of mechanically inserting the auxiliary dynamo 208 and closing the relay 210 contacts towards line DC 203. The control system 230 is set up so that it continuously measures the value of electric power generated by the various dynamos 204, 206, 208 and by the photovoltaic generator 201 , measures the power consumed by users 200 and 216 and also finds out the charge level of the pad battery 218; it can therefore decide whether to charge the pad battery or supply energy to the AC 215 network. Starting from an initial condition of contacts of relay 220 open, in the first case the control system 230 will order closure of contacts of relay 220 to al- low current to pass to the battery 218 and charge it. System 230 could simultaneously control opening of a double contact to exclude network 215 but this is not essential as, on account of greater absorption of current, the inverter 213 might not be able to increase output voltage to the value needed for transfer of power to the network 215 except in so far as it can serve the charge 216. When charging has been completed, by opening contacts 220 the battery 218 is excluded to avoid draining off current. When its charging contribution is needed, contacts 220 will be closed again so that current can be supplied direct to the recharging station 21 1.

Referring to the plant in Figure 1 , the constructional and operative principles of the wind and photovoltaic generators are already well known and needs no further explanation. Little is as yet known, however, about a wharf capable of exploiting wave motion using the mechanics of rotation and orthogonal transmission described above. This capability is derived from the long sequence of floats fitted with arms for transmitting to a mechanical shaft the torque generated by hydrodynamic thrust sequentially exerted on the floats by the incoming wave. It is well known that marine waves lose speed on nearing the coast and entering shallow water, becoming higher and acquiring horizontal thrust. Well- documented studies affirm that on the Italian coast the power available in a metre of wave front varies from 8 to 12 kW/m. It follows that a considerable amount of power can be extracted from wave motion by the wharf in Figure 1 , which has a 133 m long and 15 m wide section equipped with four rows of spherical floats. The floats intercept the wave in sequence receiving its hydrostatic thrust opposing to it the resistance encountered by the arm levered on the bearing of the transversal shaft. Some approximate calculations will be given here to indicate the sort of size the project involves, though without any pretence at rigorous accuracy. As. there are 40 floats outside the wharf and another 40 under- neath it, each having a diameter of about 4 m and a volume of 33.5 m ³ , the total theoretical float volume deployed by the 80 floats is 2,680 m ³ , of which much more than half can be exploited to extract power from the upward thrust of the incoming waves, the inactive float being under water for less than the length of the radius. Adjacent floats are 7 m apart thus making possible a rise of over 5 m under pressure from the higher waves to lift the arm almost up to the surface of the wharf. Under these extreme conditions peak power is considerable: assuming that waves remain for 4 seconds, the mass of water that contributes to upward thrust is 1 ,340 m ³ equivalent to a hydrodynamic force of 13,145,400 N that generates a moment of 65,727,000 Nxm. Assuming a rotation of 60° in 4 s and therefore an angular speed of 0.0416 Hz/s (equivalent to ω = 0.261 rad/s) a peak power of 3,430,845 Wpeak is reached at the dynamo shaft. In more normal conditions with waves 1 m high and in the same time, peak power is likely to fall by a 5 factor to about 686 kWpeak, mechanical losses excluded. This value is equivalent to 8.58 kW per float equivalent to an ideal 85.8% of the theo- retical power of 10 kW/m from the incoming wave. According to the Douglas scale an average value of 1 m per wave height in open sea corresponds to a condition described as from not very rough to rough and, according to the Beaufort scale, represents force 3 (tending to force 4) with a wind of about 19 km/h. Bearing in mind that waves tend to rise as they reach the coast, 1m seems too high to be considered as an average value over 1 year, while a value of 0.6 m caused by a wind of 12 km/h would seem more reasonable for the place chosen. Adopting the value of 0.6 m as average local wave height over one year, the equivalent average power would be 411.6 kW from which to subtract the passive contribution due to friction created by the mechanical part comprising: 80 bevel gear couplings, 80 one-way joints, 80 bearings on the transversal shafts, various cardan joints, and the bearings supporting the longitudinal shaft. In spite of the high number of mechanical couplings, losses are reasonably low for two reasons: firstly, because couplings engage the longitudinal transversal shaft singly and overall efficiency is therefore a weighed average of each single one; secondly, couplings take place in sequence and when completed friction is considerably less. Adopting an approximation by excess, a loss of mechanical power may be assumed as 10% that reduces power to 370.44 kW (average over a long period) at the dynamo shaft. It must be stated that dynamo efficiency varies with variations in the power delivered to the charge according to a typical trend that increases rapidly from zero (loadless dynamo) to the highest value then slowly falls as losses in the armature increase. Assuming maximum dynamo efficiency as being 80%, 315 kW of power would be available at the charge (average over a long period).

In Figure 1 the area covered by solar panels projected onto the surface of the wharf, to allow for the angle of incidence of solar radiation, is a rectangle of 185 x 15.6 = 2,886 m ² . Taking a plant producing 1 kW of rated power as a refer- ence, with excellent orientation and inclination and with no shade, the Energy Authority in Italy has made the following estimate of maximum possibilities of production: northern regions 1 ,000-1 ,100 kWh/year; central regions 1 ,200-1 ,300 kWh/year; southern regions 1 ,400-1 ,500 kWh/year. Taking as an example 1 ,200 kWh/year, this gives an average power of about 144 W _mea n value (if avail- able night and day). Knowing that the surface occupied by polycrystalline silicon photovoltaic modules is about 7.5 m ² /kWp, also equivalent to 7.5 m ² /kW _mea n, annual average power produced by the entire roof of solar panels would be around 55.4 kW _mean , capable of a continual supply of power to about 18 domestic consumers using 3kW but would be insufficient if having to supply power to the station for systematically recharging the batteries of the electric vehicles. In Figure 1 , the rotor of the wind turbine carried by the tower 10, at a height of 48 m, carries three blades each 20 m long. A plant of this kind can generate about 30 kW _mean of average power over one year; rated power can obviously reach 600 kW. In modern aero-generators able to exploit low levels of wind, minimum wind speed enabling the turbine to supply the power for which it was designed, lies between 12 and 15 m/s which agrees with the value indicated for the floats while wind speeds over 25 m/s would mean deactivating the generator for reasons of safety.

Adding up the three preceding contributions: from wave motion 315 kW _mea n, from solar 55.4 kW _mea n, and from wind 30 kW _mea n, making a total of 400.4 kW _mea n which being integrated are always available night and day all the year round (apart from simultaneous and unlikely absence of energy from the three sources and from the pad battery); rated values over a short period can be considerably higher. In the best possible case in which the three sources simultaneously supplied rated power values, this would be:

(686 x 0.85) kW _wave motion + 600 kW _win d + 382 1.565 MW _rate d.

A considerable fraction of the value always available 400.4 kW _mea n will be devoted to recharging the batteries of the electric vehicles, today mainly consisting of a plurality of lithium ion accumulators of various sizes. It is expected that progress will quickly be made to increase charging capacity and therefore car autonomy, and to reduce charging time, requirements that together make greater peak power necessary at the station. It may reasonably be presumed that batteries will have a capacity of 35 kWh and a recharging time of 4 hours; estimating total consumption of an electric car at 0.33 kWh per km, autonomy would be 106 km. With average power available, the charging station could simultaneously serve 10 cars, a further 50.4 kW remaining unused, of which 10.4 kW could go to local users and 40 kW be put into the low-voltage electricity mains.

Referring to the above, it would seem that never before has such vast and complementary integration of synergic exploitation of renewable energy from wind, solar, and wave-motion sources been attempted such as that possible by the plant 1 in Figure 1. The core of such integration consists of the interfacing means between electric generators and the charge that appear as a single generator for a more constant and continuous supply to the charge. The interfacing means hitherto described include DC/DC converters which, in the configuration given in Figure 7, can automatically combine the contributions of power at different rated voltages bringing them to a common voltage dictated by the DC charge. These same means also include an inverter fed by the common DC level to obtain an AC power to supply at the voltage dictated by the AC charge. It is advantage to use several DC/DC converters with outputs in parallel as in this way each converter can stabilize the voltage on the charge independently from the others, obviously when this is possible in feedback according to PWM technique, suiting the power supplied to the charge to is own generating capac- ity.

The use of DC/DC converters, while advantageous, in no way limits the invention because different interfacing means carrying out similar functions could be provided. An alternative example originates in using alternators, respectively wind and wave-motion operated, and a (DC/AC) inverter downstream of the photovoltaic generator; three transformers then returning the three AC voltages to a single level, the three transformed voltages are rectified and applied in parallel to the terminals of the charge. This solution is much less efficient for stabilizing the voltages of single generators according to their absorption of the common charge; it would in fact be necessary to introduce a Zener diode in parallel to each voltage rectified, or alternatively use an electronic voltage regulator, of the series or parallel type, involving a reduction in conversion efficiency. A further example uses four inverters in place of the four DC-DC converters, three of which are so designed as to generate alternating current at a common voltage higher than that imposed by the DC charge; this current must be recti- fied and levelled bringing it to the value imposed by the charge. The fourth inverter is identical to inverter 213 and connected in the same way. The solution described is in every way equivalent to that which uses the four DC-DC converters, both the inverters and the DC-DC converter belonging to a common family of switching feeders.

As a check on the operational aspect, it should be stated the Figure 1 shows the plant in its final form, the invention hitherto realized being a prototype of a smaller size but with all its component parts functioning perfectly and fully inte- grated. As regards exploitation of wave motion to activate a dynamo, the first prototype realized had a single shaft in the mechanics of the wharf 4, equipped with two parallel rows of floats, one row on each side in relation to the shaft, but fewer than in the final realization. The prototype was brought to perfection in a tank of water where wave motion of variable frequency and height was created, from time to time measuring the power generated. Maximum wave height was scaled down by the ratio between length of float arms of the prototype and their length in the ultimate version, so as to reproduce equivalent transversal shaft rotations. The perfected prototype was then taken to a chosen place on the coast, usually windy, and the frame was rigidly fixed to a pier so that the floats could be hit by marine waves of the required kind (choosing the most suitable days). Solar panels were mounted on the base of the pier as well as a generator of wind power of the same type as shown in Figure 1. Rated power levels of the solar and wind generators, compared with their final value, were scaled to a value equal to the ratio existing between the overall volume of the prototype floats and the overall volume of the floats in their final form, this reduction consisting in a smaller surface both photovoltaic and of wind interception by the blades. The reduction of scale in the dimensions of the blades was corrected to allow for wind speed rising with the increased distance from land. All this hav- ing been decided, the terminals of the two dynamos and of the photovoltaic generator were connected to the respective inputs of the DC/DC converter with output at 12 V. Outputs of the three DC/DC converters were connected in parallel to feed common car accumulators; overall capacity of the accumulators was scaled as stated above compared with the capacity planned for the battery re- charging station in the ultimate version. An additional accumulator was connected in parallel to the others to check for any surplus energy produced. Ammeters with digital output were inserted in series at the outputs of each generator and at the charge so that the contribution of power supplied by each one and the integrated power supplied to the charge could be recorded and traced in the 24 hours. The results obtained by the prototype proved to be up to expectations because the accumulators were charged within the recommended time for charging, including additional time. Based on the description given of a preferred example of realization of the invention, some changes may be thought necessary by an expert in the field without thereby departing from its sphere as will appear from the following claims.