The present invention relates to an arrangement for energy recovery from mo tions of a floating structure as defined in the preamble of claim 1.

Typical floating structures in the sense the invention are among other things ships and offshore platforms such as oil and gas platforms or floating wind tur bines. Particularly, ships or vessels, such as oil tankers are suitable applications for the arrangement according to the invention. Later only a term“ship” is used when all floating structures are meant. In exceptional cases also other terms may be used.

When ships are under away or anchored offshore, for example waiting for load ing or refueling, they are in most cases in a continuing motion because of the wind and waves. These motions are typically rolling, pitching, yawing, heaving, swaying and surging. Later a common expression“swinging” is used for these motions. In exceptional cases also the above-mentioned real terms or other terms may be used.

The swinging motions of the ship are not properly utilized to recover the kinetic energy of the motions and to store the recovered energy. One problem in recov ering is the storing of the recovered energy. Electrical energy is generally stored in accumulators of different sizes and capacities. Large electrical energy storage structures comprise, for instance, large containers equipped with li-on accumula tors. These storages can be used as disturbance reserve to balance needs of electric network by preventing unnecessary electrical interrupts. In that way the quality of the electricity of the electric network can be improved. A disadvantage with the large electrical energy storage structures is that they are expensive, their active lifetime is short, and they are harmful to environment because after use they are mostly hazardous waste which is difficult to dispose. They also re quire additional infrastructure to protect against the fire hazard and their charg ing/discharging rates are low.

In prior art, attempts have been made to construct more environmentally friendly energy storage systems than the large electrical energy storage structures men tioned above.

International patent publication WO2017066826 A1 presents a wind turbine power storage and regeneration system where the recovered wind energy is stored as a hydraulic fluid pressure in a storage vessel. The solution of the WO publication is intended only for collecting wind energy. No other energy sources have been mentioned.

United States patent US9774230 B2 presents a generator set having a coupling member between a flywheel and a generator. The generator set includes a fly wheel coupled to the crankshaft of the engine. The flywheel may be used for en ergy storage purposes. The flywheel may be configured to convert a rotational power generated by the engine into an electric power. No other energy sources have been mentioned in this connection either.

The object of the present invention is to eliminate the drawbacks described above and to achieve a versatile, economical and efficient arrangement for ener gy recovery from motions of a floating structure. Another object of the present invention is to achieve an environment friendly, economical and efficient ar rangement for storing the energy, preferably the energy recovered from the mo tions of a floating structure, such as a ship. The arrangement for energy recovery from motions of a floating structure according to the invention is characterized by what is presented in the characterization part of claim 1. Other embodiments of the invention are characterized by what is presented in the other claims. An aspect of the invention is to provide an arrangement for energy recovery from motions of a floating structure, such as a ship, oil tanker, ocean liner or offshore platform, which floating structure comprises at least a deck above the water lev- el, an anchoring arrangement for anchoring the floating structure at its location and an electric system. Advantageously, the arrangement comprises an energy recovery assembly having one or more energy recovery units that are arranged to recover kinetic energy from motions of the floating structure. The solution of the invention has significant advantages over the solutions of the prior art. The number of relatively small energy recovery units with or without a power-take-off (PTO) units and/or hydraulic pressure accumulators and/or fly wheel mechanisms make it possible to recover kinetic energy from the motions of the ship and to easily storage the recovered energy for further use. An additional advantage is that the arrangement of the invention is not high priced and is envi ronmentally acceptable. Service and maintenance are also easy and fast to per form. In addition, energy recovery units are easy to install into cooperation with various functions of the ship. For instance, an energy recovery unit can be easily fitted to the existing rudder steering gear or mechanism with minimal costs. The energy recovery units can also be fitted to anchoring arrangement, for instance to mooring lines or anchor ropes or chains. In this way sudden shock loads in lines, ropes or chains can be reduced and thus life span of the lines, ropes or chains can be increased. One more advantage of the arrangement is that the energy storage arrangement of the invention is capable to save the recovered energy in a high speed.

In the following, the invention will be described in detail by the aid of examples by referring to the attached simplified and diagrammatic drawings, wherein Fig. 1 presents in a simplified oblique top view a ship, such as oil tanker, equipped with the arrangement according to the invention, Fig. 1 a presents in an oblique top view and in a simplified and diagrammatic way an energy recovery unit placed on the deck of the ship of Fig. 1 to recover kinetic energy from rolling motions of the ship,

Fig. 2 presents in an end view and in a simplified and diagrammatic way in a neutral straight position a floating ship equipped with another en ergy recovery unit placed to recover energy from the anchor ropes or chains or mooring lines when the ship is rolling,

Fig. 3 presents in a simplified and diagrammatic way the ship according to

Fig. 2 in a first rolling position,

Fig. 4 presents in a simplified and diagrammatic way the ship according to

Fig. 2 in a second rolling position,

Fig. 5 presents in a top view and in a simplified and diagrammatic way the reciprocating hydraulic cylinder arrangement of the energy recovery unit presented in Fig. 2 in a neutral middle position,

Fig. 6 presents in a top view and in a simplified and diagrammatic way the reciprocating hydraulic cylinder arrangement of the energy recovery unit presented in Fig. 2 in a first extreme position,

Fig. 7 presents in a front view and in a simplified and diagrammatic way a hawse pipe of a ship,

Fig. 8 presents in a front view and in a simplified and diagrammatic way yet another energy recovery unit according to the invention to be in stalled in front of the hawse pipe presented in Fig. 7,

Fig. 9 presents in a front view and in a simplified and diagrammatic way the energy recovery unit of Fig.8 installed in front of the hawse pipe pre sented in Fig. 7,

Fig. 10 presents in a side view and in a simplified and diagrammatic way the energy recovery unit of Fig. 8 installed in front of the hawse pipe presented in Fig. 7, Fig. 11 presents in a top view and in a simplified and diagrammatic way yet another energy recovery unit according to the invention in the neutral middle position and installed into the rudder steering mechanism of a ship,

Fig. 12 presents in a top view and in a simplified and diagrammatic way the energy recovery unit according to Fig. 10 in the first extreme posi tion,

Fig. 13 presents in a front view and in a simplified and diagrammatic way a ship with a stabilizer element on both sides of the ship,

Fig. 14 presents in a simplified oblique top view a part of a side and bottom of a ship and one of the stabilizers presented in Fig. 13, and Fig. 15 presents in a side view and in a simplified and diagrammatic way one type of hydraulic pressure accumulator structure according to the in vention comprising a hydraulic accumulation rack with a weighing system.

The basic idea of the present invention is to achieve an arrangement, which comprises one or more hydraulically operated energy recovery units to recover the kinetic energy from motions of a floating structure, such as a ship, oil tanker, offshore platform, and so on, and to store the recovered energy to one or more energy storage units of an energy storage arrangement. The arrangement also comprises means to convert the recovered energy to another type of energy. One kind of a hydraulic energy recovery system that can be used in the ar rangement according to the invention is presented in the US patent US9631599.

Fig. 1 presents in a simplified oblique top view a ship 1 , such as an oil tanker, equipped with the arrangement according to the invention. The ship 1 comprises a deck 2, a hull 3, a stern 4 and a bow 5. In addition, the ship 1 comprises an anchoring arrangement 6 having one or more anchor chains, lines or ropes 7, later only anchor ropes 7, and a hawse pipe 8 with its center hole 22 in the bow of the ship 1 for the anchor ropes 7. Further, the ship 1 comprises a superstruc ture 4a and a rudder steering gear arrangement, shorter a steering mechanism, and also the ship 1 comprises a rudder. Advantageously, the energy storage arrangement 9 according to the invention is placed on the deck 2 of the ship 1. Preferably, the energy storage arrangement 9 comprises a hydraulic pressure accumulator structure 9a comprising a control system, oil tank, inverter, hydraulic motors and/or generators and pumps, and one or more hydraulic accumulator packages connected to the hydraulic motors and/or generators and pumps and to the oil tank. The hydraulic accumulator packages may be connected to each other through an appropriate manifold ar rangement.

In addition, the energy storage arrangement 9 according to the invention may comprise a flywheel mechanism 9b with one or more flywheels.

The energy storage arrangement 9 may consist of one or more energy storage units that may be hydraulic accumulator packages and/or flywheel packages. The energy storage arrangement 9 also comprises inputs for energy recovery units placed in different position and functions of the ship 1 , and outputs to deliv er the stored energy for further use. The recovered energy is arranged to be brought to the energy storage arrangement 9 as a pressurized hydraulic flow. Hydraulic pipes 11 are arranged to convey the energy recovered by a first ener- gy recovery unit 10 to the energy storage arrangement 9. Further, hydraulic pipe system 12 are arranged to convey the energy recovered by one or more other energy recovery units to the energy storage arrangement 9. Such energy recov ery units may be, for example, an energy recovery unit coupled to the rudder steering mechanism of the ship 1 and/or an energy recovery unit coupled to the stabilizer mechanism inside the hull 3, which stabilizer mechanism comprises stabilizer elements outside the hull 3 on both sides of the ship 1.

Preferably, the components of the energy storage arrangement 9 are placed in one or more replaceable containers, such as a sea container. However, the en ergy storage arrangement 9 may also be placed in another type of a shelter. In the embodiment example of Fig. 1 the hydraulic pressure accumulator structure 9a is placed in two containers but the flywheel mechanism 9b is placed in a dif ferent kind of a shelter.

Fig. 1 a presents in an oblique top view and in a simplified and diagrammatic way an energy recovery unit 10 placed on the deck 2 of the ship 1. The energy re covery unit 10 is oriented in a transversal position in relation to the ship’s longi tudinal direction and is arranged to recover energy mainly from rolling motions of the ship 1. For that purpose, the energy recovery unit 10 comprises a mass 13 guided by two guide rails 14 and arranged to move along the guide rails 14 by gravity, hydraulic cylinders 15, end plates 16 and hydraulic pipes 17. The hy draulic cylinders 15 are placed between the mass 13 and the end plates 16 so that when the mass 13 moves along the guide rails 14 towards the first direction it simultaneously pulls the piston of the first hydraulic cylinder 15 and pushes the piston of the second hydraulic cylinder 15. When the mass 13 moves along the guide rails 14 towards the opposite direction it simultaneously pulls the piston of the second hydraulic cylinder 15 and pushes the piston of the first hydraulic cyl inder 15. The mass 13 moves along the rolling motion of the ship 1. The recipro cating motion of the mass 13 causes a pressure in the first and second hydraulic cylinder 15 in turns, and that pressure is conveyed to the energy storage ar rangement 9 through the hydraulic pipes 17.

Though the energy recovery unit 10 is placed in the transversal direction in rela tion to the longitudinal direction of the ship, it can also be placed in the longitudi- nal direction of the ship 1. In that case its main purpose is the recover the kinetic energy from the pitching motion of the ship 1. The arrangement of the invention may comprise one or more energy recovery units 10 placed in different locations in the ship 1 , also under the deck 2.

Figs. 2-6 present another type of energy recovery unit according to the invention. Fig. 2 presents in an end view and in a simplified and diagrammatic way a float ing ship 1 in a neutral straight position. Fig. 3 presents the ship 1 in a first rolling position and Fig. 4 presents the ship 1 in a second rolling position. The rolling positions presented in Figs. 3 and 4 may be the extreme rolling positions of the ship 1. Fig. 5 presents in a top view and in a simplified and diagrammatic way the reciprocating hydraulic cylinder arrangement of the energy recovery unit 18 in its neutral middle position, and Fig. 6 presents the same hydraulic cylinder arrangement in its first extreme position. The energy recovery unit 18 is arranged to recover energy from the anchor ropes 7 mainly when the ship 1 is rolling. For the sake of clarity, only a coupler element 20 of the energy recovery unit 18 is presented in figures 2-4.

The hydraulic cylinder arrangement of the energy recovery unit 18 comprises preferably two in opposite direction working hydraulic cylinders 19 that are fas tened, for example, onto the deck 2 of the ship 1. Each hydraulic cylinder 19 comprises at least one connection 21 at its end to connect the hydraulic cylinder 19 to the energy storage arrangement 9 by a hydraulic pipe.

The free ends of the piston rods are fastened to the coupler element 20, each piston rod in its own side. The coupler element 20 is further fastened to the an chor rope 7 that in this case is a double-sided version. It means that the continu ous anchor rope 7 extends from one side of the ship 1 to another side of the ship 1 and an anchor is in its both ends. This kind of the energy recovery unit 18 can also be used in spread mooring systems. The energy recovery unit 18 coupled the anchor rope 7 is arranged to work so that in the neutral floating position presented by Fig. 2 the centre of gravity and the centre of buoyancy are aligned, and the coupler element 20 is in its neutral middle position. Fig. 3 presents the situation where the heeling caused by wind and waves from the starboard side of the ship 1 causes the starboard anchor rope 7 to tighten, which forces the coupler element 20 to the starboard direction. Simultaneously, the pressure in the hydraulic cylinder 19 of the starboard side increases. After a while the righting lever formed by the centre of gravity and centre of buoyancy causes the ship 1 to right itself and the coupler element 20 returns towards its middle position. In most cases the ship 1 heels over its neu tral position as presented in Fig. 4. In that case the pressure in the opposite hy draulic cylinder 19 increases. So, the hydraulic cylinders 19 work in turns. The arrangement may also be coupled so that the energy recovery unit 18 is fas tened to only one anchor rope 7 that is only in one side of the ship 1. In that case a counterweight can be used to return the coupler element 20 to its neutral posi tion when the anchor rope 7 slackens. Figs. 7-10 present yet another type of energy recovery unit 23 according to the invention. Fig. 7 presents in a front view and in a simplified and diagrammatic way a hawse pipe 8 of a ship 1. Preferably the hawse pipe 8 is on the side shell plate 5a of the bow 5 or the ship 1. Fig. 8 presents in a front view and in a simpli fied and diagrammatic way solely the energy recovery unit 23 to be installed in front of the center hole 22 of the hawse pipe 8. Fig. 9 presents in a front view and Fig. 10 presents in a side view the energy recovery unit 23 installed in front of the hawse pipe 8. For the sake of clarity, the figures are simplified and the fastening and supporting structures of the energy recovery unit 23 are not pre sented in figures. The energy recovery unit 23 comprises a frame 24 that is fastened in front of the hawse pipe 8, either to the hawse pipe 2 or the side shell plate 5a of the bow 4 or to the both. Further, the energy recovery unit 23 comprises a follower ring 25 that is coupled to the frame 24 through a group of hydraulic cylinders 26. Prefer ably, the number of hydraulic cylinders 26 is four but they can also be more or less, for example two or three. The hydraulic cylinders 26 are placed around the circumference of the follower ring 25 in even distances, in case of four hydraulic cylinders 26 they are at intervals of 90 degrees. The hydraulic cylinders 26 are hinged at their both ends so that they can turn into slant positions.

The anchor rope 7 is passed through the follower ring 25 so that the motions of the anchor rope 7 in the hawse pipe 8 move the position of the follower ring 25. In that case also a pressure in one or more hydraulic cylinder increases and so recovered kinetic energy is conveyed through hydraulic pipes to the energy stor age arrangement 9.

Figs. 11 -12 present yet another type of energy recovery unit 35 according to the invention. Fig. 11 presents the energy recovery unit 35 in the neutral middle po sition and installed into the rudder steering mechanism 27 of the ship 1. Fig. 12 presents the energy recovery unit 35 in its first extreme position.

The steering mechanism 27 is for controlling the turning position of the rudder shaft 28 of the ship 1. Turning the rudder shaft 28 simultaneously turns also the rudder of the ship 1. The steering mechanism 27 comprises at least a substan tially symmetrical coupling element 29 that is fastened to the rudder shaft 28. At its both far ends the coupling element 29 comprises a round ended slot 30 to which a linearly moving dowel like counter element 31 is placed. The steering mechanism 27 further comprises two pairs of steering hydraulic cylinders 32 that are arranged in each pair to work in the opposite directions. The steering hy draulic cylinders 32 in each pair have a piston rod 33 that is in common for both the steering hydraulic cylinders 32 in the pair. The counter element 31 is fas tened to the piston rod 33 so that in the neutral middle position, that is presented in Fig. 11 , the counter element 31 is at an equal distance from both the steering hydraulic cylinders 32. At the same time the pistons inside the steering hydraulic cylinders 32 are substantially in the middle of the steering hydraulic cylinders 32 so that they can move linearly an equal distance in both directions in their motion direction. When the steering mechanism 27 is in use the pistons, piston rods 33 and the counter elements 31 all make a reciprocating linear motion. Further, the steering hydraulic cylinders 32 comprise rod end ports 34 and cap end ports 34a to connect each steering hydraulic cylinder 32 to a hydraulic pump and/or a hy draulic container.

The energy recovery unit 35 according to this embodiment of the invention com prises a hydraulic cylinder 36 with a piston and a piston rod 37. The hydraulic cylinder 36 comprises at its both ends a connection 39 to connect the hydraulic cylinder 36 to the energy storage arrangement 9 by the hydraulic pipe system 12. The energy recovery unit 35 is coupled to the rudder steering mechanism 27 through a coupler mechanism that comprises a coupler element 38 that is fas tened at its first end to the counter element 31 and coupled at its second end to the free end of the piston rod 37 of the hydraulic cylinder 36.

The energy recovery unit 35 coupled the steering mechanism 27 is arranged to work so that in the neutral position presented in Fig. 11 when the rudder is in its middle position also the counter element 31 is in its middle position. Fig. 12 pre sents the situation where the rudder has been turned, either when the ship is in a motion or anchored or moored. It must be understood, that normally this would only work when the steering gear is not active, i.e. whilst the ship is at anchor, surging on the anchor due the wind and wave. In this case the piston in the hy draulic cylinder 36 has moved from its neutral middle position towards the sec ond end of the hydraulic cylinder 36 and the pressure at the second end has in- creased. This means that kinetic energy from a motion of the rudder has been recovered, and it is to be conveyed to the energy storage arrangement 9 through the connection 39 and further through the hydraulic pipe system 12. When the rudder is turned to the opposite direction the pistons and piston rods 33 move also to the opposite direction. In that case the piston rod 37 comes out wards from the hydraulic cylinder 36 towards its neutral middle position, and if the motion of the rudder is big enough the piston rod 37 comes out from the hy draulic cylinder 36 as far as to its second extreme end, opposite the first extreme end.

Thus, the energy recovery unit 35 is arranged to recover the kinetic energy of the rudder steering mechanism 27 in both the motion direction and also substantially continuously in all positions between the neutral position of the rudder and its both extreme positions.

The arrangement may also be coupled so that the energy recovery unit 35 is coupled to both the pairs of the steering hydraulic cylinders 32. Also, two energy recovery units 35 can be coupled to one pair of the steering hydraulic cylinders 32. For instance, about the same way as has been done in the energy recovery unit 18 in Figs. 5 and 6. In that case the hydraulic cylinders 36 work in turns.

Figs. 13-14 present yet another type of energy recovery unit according to the invention. Fig. 13 presents in a front view and in a simplified and diagrammatic way a ship 1 with a stabilizer mechanism 40. Only stabilizer elements 41 of a wing type are seen outside the hull 3 of the ship 1 on both sides of the ship 1. Fig. 14 presents in a simplified oblique top view a part of a side and bottom of the ship 1 and one stabilizer element 41 on one side of the hull 3 of the ship 1. The actual stabilizer mechanism 40 is placed inside the hull 3 of the ship 1 . The stabilizer mechanism 40 comprises hydraulically controllable actuators for mov ing the stabilizer elements 41 so that they are rotated and tilted depending on the needed corrective action.

The hydraulically controllable actuators make it possible to couple one or more energy recovery units 42, substantially such like described above, to the stabi lizer mechanism 40 substantially in the same way as described above. Thus, the hydraulically controllable actuators are arranged also to move the pistons of the energy recovery units 42, and so the kinetic energy of the hydraulically control lable actuators of the stabilizer mechanism 40 of the ship 1 is arranged to be recovered. From the energy recovery units 42 coupled to the stabilizer mecha nism 40 the recovered energy is conveyed to the energy storage arrangement 9 for instance through the hydraulic pipe system 12.

Fig. 15 presents in a side view and in a simplified and diagrammatic way one type of hydraulic pressure accumulator structure 9a according to the invention comprising a hydraulic accumulation rack construction 43 equipped with a group of pressure pipes 44, a manifold 45 and one or more weighing elements 46. The pressure pipes 44 are filled with a gas and liquid, such as hydraulic oil. The en ergy is stored in the pressure pipes 44 as a pressure. In Fig. 15 the three lower most pressure pipes 44 are full of oil. Thus, their filling level is 100%. Corre spondingly, the two uppermost pressure pipes 44 comprise both oil and gas. Thus, the gas in the pressure pipes 44 can still compress and the amount of oil can increase. The filling level in these uppermost pressure pipes 44 is not yet 100%.

The arrangement comprises means for monitoring the filling level of the pressure pipes 44 of the hydraulic accumulation rack construction 43. The means for mon itoring the filling level preferably comprises one or more weighing elements 46 that are installed to measure the weight of the hydraulic accumulation rack con struction 43. The weight tells how much oil and/or gas is in the pressure pipes 44 when the hydraulic accumulation rack construction 43 is in a normal use. Moni toring the filling level of the pressure pipes 44 by the help of weighing in a swing- ing and moving rack construction 43 installed on a floating structure, such as a ship 1 , is preferably done with multidimensional calculation with velocity and ac celeration in all directions all the time.

As a conclusion, the arrangement according to the invention for energy recovery from motions of a floating structure comprises an energy recovery assembly hav ing one or more energy recovery units 10, 18, 23, 35, 42 that are arranged to recover kinetic energy from motions of the floating structure, such as the ship 1 mentioned above. Preferably, the energy recovery assembly comprises one or more power-take-off (PTO) units to convert the recovered energy to another type of energy. In addition, the arrangement comprises an energy storage arrange ment 9 with one or more energy storage units connected to the energy recovery assembly for storing the energy recovered by the energy recovery units 10, 18, 23, 35, 42. International patent publications WO2015177400 A1 and WO2015193532 A1 present hydraulic power-take-off (PTO) units that can be used also in the ar rangement according to the present invention.

Preferably, the arrangement according to the invention also comprises means for desalination of seawater with the energy recovered by one or more energy re covery units 10, 18, 23, 35, 42 of the energy recovery assembly of the floating structure. This is because the pulsating nature of the recovered energy is smoothed by the accumulators thus ensuring that the output can be used as small pressure for desalination sea water with membranes or distillation. Preferably, the arrangement according to the invention also comprises means for momentarily increasing the power supply when large momentary power is re quired. In that case the additional power is needed, for example, to give extra power supply to starting electric devices, such as electric motors, for example, in a ship 1 a bow thruster motor. The additional momentary power is preferably taken from the energy storage arrangement 9 according to the invention, for in stance either from the hydraulic pressure accumulator structure 9a or from the flywheel mechanism 9b. It is obvious to the person skilled in the art that the invention is not restricted to the examples described above but that it may be varied within the scope of the claims presented below. Thus, for example, the structures and positions of the energy recovery units can be different from what is presented.