SUPPORTING FOUNDATION FOR A HYDROKINETIC TURBINE, AND RELATED UNDERWATER DEVICE AND INSTALLATION METHOD

Abstract

The invention relates to a supporting foundation (20) including a base (50), a marine current turbine carrier (54) supported by the base (50), and at least three legs (52) for bearing on the floor of the body of water (14), connected together by means of the base (50). Each bearing leg (52) comprises a hollow casing (70), and a rigid member (72) for adjusting the vertical position of the hollow casing (70) relative to the floor (12) of the body of water. The rigid adjustment member (72) is immobilized so as to vertically project under the casing (70). Each bearing leg (52) further includes a member (74) for engaging with the floor of the body of water (14) and rigidly connected to the lower end of the rigid adjustment member (72).

Description

The present invention relates to a supporting foundation for a hydrokinetic turbine, intended to be laid on the floor of a body of water, the supporting support comprising:

• • a base;
  • a hydrokinetic turbine carrier supported by the base;
  • at least three legs for bearing upon the floor of the body of water, connected together by means of the base, each bearing leg including a hollow casing.

Such a supporting foundation is intended to be placed bearing upon the floor of a body of water, in which marine or hydraulic currents are present.

This body of water may for example be an ocean, or a sea, in which case the hydraulic or marine currents in particular result from the tides or the swell. Alternatively, the body of water is a river or a waterway, in which hydraulic or marine currents notably result from the flow between the source and mouth of the body of water.

The supporting foundation bears and fixes on the bottom of the body of water a hydrokinetic turbine including a turbine and an alternator. The hydrokinetic turbine is capable of collecting the hydraulic energy resulting from the water circulation, as mechanical rotational energy, by means of the turbine, and of transforming the mechanical energy into electric energy by means of the alternator.

Considering the potential force of the current which may be exerted on the hydrokinetic turbine, it is important that the supporting foundation maintains the hydrokinetic turbine very firmly in position on the floor of the body of water, while retaining as much as possible the orientation of the hydrokinetic turbine for optimizing its energy production.

In order to ensure good stability to the hydrokinetic turbine, the use of a supporting foundation of the tripod type is known, as described for example in WO 2008/110811 and EP 1 992 741.

The supporting foundations comprise a central base bearing the hydrokinetic turbine and three vertical legs intended to be sunken into the floor of the body of water.

Each leg comprises a casing open downwards which is sunken into the floor of a body of water, once the supporting foundation is laid on this floor.

In WO 2008/110811, the casing is further ballasted in order to stabilize the supporting foundation on the floor of the body of water.

Such supporting foundations are well adapted for substantially flat floors and have sufficient rigidity for preventing too large sinking of the supporting foundation into the floor.

If the floor is not flat, it is necessary to prepare the floor of the body of water both for ensuring some flatness, and for guaranteeing that the floor is not too soft.

This prevents the supporting foundation from sinking into the subsoil in an uncontrolled way and guarantees the orientation of the hydrokinetic turbine in a horizontal plane and in a vertical plane.

Such a preparation of the floor of the body of water is time-consuming and consumes heavy means, since it is necessary to mobilize ships specialized in underwater earthmoving.

An object of the invention is to obtain a foundation supporting a hydrokinetic turbine which may be positioned in a simple and inexpensive way on any type of sea floor, notably those having a floor provided with reliefs and/or soft areas.

For this purpose, the object of the invention is a supporting foundation of the aforementioned type, characterizing that each bearing leg further comprises:

• • a rigid member for adjusting the vertical position of the casing relative to the floor of the body of water, the rigid adjustment member being immobilized so as to vertically protrude under the casing;
  • a member for engaging with the floor of a body of water, rigidly connected to the lower end of the rigid adjustment member.

The supporting foundation according to the invention may comprise one or more of the following features, taken individually or according to any technically possible combination(s):

• • at least two of the adjustment members have different heights, taken between the casing and the engaging member;
  • each adjustment member comprises an element which may be deployed towards the floor of the body of water relatively to the casing before installing the supporting foundation on the floor of the body of water;
  • each adjustment member comprises a fixed element relative to the casing, the deployable element being moveably mounted relatively to the fixed element before installing the supporting foundation on the floor of the body of water, the fixed element and the deployable element being in particular formed by telescopic tubes;
  • each casing comprises at least one bottom wall and a side wall delimiting an inner space able to be filled with gas in order to ensure floatability specific to the supporting foundation on the body of water;
  • the casing comprises an upper wall obturating the inner space upwards, the casing including at least one tapping for injecting and/or purging fluid in the inner space.
  • the inner space permanently opens out upwards above the side wall;
  • one of the engaging members delimits a cavity opening downwards, intended to be inserted into the floor of the body of water;
  • the cavity is delimited by a hollow receptacle opening downwards and having an upper obturation wall towards the top of the cavity;
  • one of the engaging members comprises a totally solid, in particular convex, lower surface in order to oppose the penetration of the engaging member into the floor of the body of water.

The object of the invention is also an underwater electric power generation device characterized in that it comprises:

• • a supporting foundation as defined above;
  • a hydrokinetic turbine mounted on the hydrokinetic turbine support.

The object of the invention is also a method for setting into place a supporting foundation as defined above comprising the following steps:

• • transporting the supporting foundation at least partly above the surface of the body of water as far as a point located facing a region for laying the supporting foundation on the floor of the body of water;
  • totally immersing the supporting foundation into the body of water;
  • arranging the legs of the supporting foundation bearing on the laying region, each engaging member being placed in contact with the floor of the body of water.

The method according to the invention may comprise one or more of the following features, taken individually or according to any technically possible combination(s):

• • it comprises a step for adjusting the height projecting from each rigid adjustment member under the casing, and then a step for immobilizing each rigid adjustment member relatively to the casing.
  • the step for adjusting the height for each protruding rigid adjustment member under the casing is carried out before total immersion of the supporting foundation in the body of water.
  • the transport step is carried out while maintaining the supporting foundation partly immersed in the body of water under the effect of its own floatability.

The invention will be better understood upon reading the description which follows, only given as an example and made with reference to the appended drawings, wherein:

FIG. 1 is a partly exploded top perspective view of a first electric power generating device comprising a supporting foundation according to the invention laid on the floor of a body of water;

FIG. 2 is a side view of the device of FIG. 1;

FIG. 3 is a view similar to FIG. 2, before its installation on the floor of the body of water;

FIG. 4 is a sectional view along a medium vertical plane of a leg of the supporting foundation of FIG. 1;

FIGS. 5 to 9 are views similar to FIG. 4 of alternative supporting foundation legs according to the invention;

FIG. 10 is a front view of a hydrokinetic turbine able to be borne by the supporting foundation of FIG. 1;

FIG. 11 is a perspective view of a three-quarter face of another hydrokinetic turbine able to be borne by the supporting foundation of FIG. 1;

FIG. 12 is a side view illustrating a laying ship and a supporting foundation according to the invention, during a first step of a first method for setting into place the supporting foundation according to the invention;

FIG. 13 is a view similar to FIG. 12, during a second step of the first installation method;

FIG. 14 is a side view of a laying ship and of a supporting foundation during a first step of a second placement method according to the invention;

FIG. 15 is a view similar to FIG. 14 during a second step of the second placement method; and

FIG. 16 is a view similar to FIG. 14 during a third step of the second placement method.

A first underwater device 10 for generating electric power according to the invention is illustrated in FIGS. 1 to 4.

This device 10 is intended to be laid on the floor 12 of a body of water 14, in order to produce electric power from hydraulic or marine currents present in the body of water 14.

The body of water 14 is for example a body of salt water having hydraulic or marine currents, such as an ocean or a sea, or a circulating body of soft water such as a waterway or a river.

The minimum depth of the body of water 14, in the region where the device 10 is laid, is greater than 5 m and is generally comprised between 20 m and 60 m.

The floor 12 of the body of water is delimited by solid material such as rocks or sediments. It has a greater surface which, in the example illustrated in FIG. 2, is provided with irregularities such as steps 16A, 16B, 16C extending at different depths relatively to the surface of the body of water 14.

The floor 12 of the body of water 14 may further have relatively more rigid areas and relatively softer areas facing the underwater device 10.

The underwater device 10 is totally immersed under the surface of the body of water 14. It comprises a supporting foundation 20 fixed and bearing on the floor 12 of the body of water 14 and a hydrokinetic turbine 22, sometimes designated by the term of “hydroelectric turbine” mounted on the supporting foundation 20 so as to protrude.

In a known way, the hydrokinetic turbine 22 comprises a base body 24 attached to the supporting foundation 20 via an attachment stud 26.

It includes a hydraulic turbine 28 rotatably mounted around a substantially horizontal axis A-A′ on the base body 24 in order to transform the hydraulic energy present in the body of water 14 into mechanical rotational energy.

The hydrokinetic turbine 22 further comprises an alternator 30 able to convert the mechanical energy resulting from the rotation of the turbine 28 into electric power.

In the exemplary hydrokinetic turbine 22 illustrated in FIG. 10, the base body 24 comprises a fairing 32 capable of guiding the water flow towards the turbine 28 along its axis of rotation A-A′ and a turbine support 34 positioned in the fairing 32.

The turbine 28 comprises a hub 36 rotatably mounted around the axis A-A′ in the turbine support 34 and a plurality of vanes 38 which protrude radially in the fairing 24 from the hub 36.

In the alternative hydrokinetic turbine 22 illustrated in FIG. 11, the base body 24 is without any fairing and the turbine 28 is mounted at one end of the turbine support 34.

Still alternatively the axis of rotation A-A′ of the turbine 28 is vertical.

In the example illustrated in FIG. 1 the attachment stud 26 comprises a substantially cylindrical upper portion 40 bearing the base body 24, an intermediate guiding portion 42 with a downward convergent shape, and a substantially cylindrical lower portion 44 intended to be inserted into the supporting foundation 20.

The lower portion 44 has a transverse dimension, taken perpendicularly to a vertical axis, smaller than the transverse dimension of the upper portion 40.

The attachment stud 26 comprises along a generatrix of the lower portion 44 a vertical guiding rib 46 intended to angularly index the hydrokinetic turbine 22 onto the supporting foundation 20 as this will be seen below.

In the example illustrated in the figures, the hydrokinetic turbine 22 is removably mounted on the supporting foundation 20 so as to be able to be brought back to the surface of the body of water 14, for its periodic maintenance, without having to bring up the supporting foundation 20. Alternatively, the hydrokinetic turbine 22 is permanently fixed onto the supporting foundation 20.

With reference to FIGS. 1 to 4, the supporting foundation 20 comprises an openworked base 50, at least three substantially vertical legs 52 bearing upon the floor 12 of the body of water 14, connected together by means of the base 50 and a hydrokinetic turbine support 54 borne by the base 50.

In the example illustrated in FIG. 1, the base 50 has an outer contour substantially with a shape of a polygon, the legs 52 being positioned at the apices of the polygon.

More specifically, the base 50 has the shape of an advantageously equilateral or isosceles triangle and the supporting foundation 20 has three legs positioned at the apex of the base 50.

Alternatively, the number of legs 52 is greater than three in order to further increase the stability of the supporting foundation 20.

The base 50 is formed by a plurality of frame members 60A, connecting the hydrokinetic turbine support 54 to each leg 52, and a plurality of frame members 60B connecting each leg 52 to two adjacent legs 52.

Thus, in the example illustrated in FIG. 1, the base 50 comprises at least two tilted frame members 60A, connecting the base 54 to each leg 52 and at least two substantially horizontal frame members 60B connecting one leg 52 to an adjacent leg 52.

The frame members 60A, 60B delimit between them water circulation spaces in order to minimize the resistance of the supporting foundation 20 to hydraulic or marine currents.

According to the invention, each leg 52 includes an upper hollow casing 70, a member 72 for adjusting the vertical position of the casing 70 relatively to the floor 12 of the body of water, fixed onto the casing 70 so as to vertically protrude under the casing 70, and a member 74 for engaging with the floor 12 of the body of water 14, positioned at the lower end of the adjustment member 72 in contact with the floor 12.

Each leg 52 further comprises a fastening element 76 to a line of descent of the supporting foundation 20 in the body of water 14.

As illustrated by FIG. 4 each casing 70 delimits an inner floatability and ballasting space 78, intended to be selectively filled with a gas for ensuring floatability of the supporting foundation 20 during its transport and with a ballast solid or liquid for ensuring the stability of the supporting foundation 20 on the floor 12 of the body of water 14 after laying the supporting foundation.

Each casing 70 has a substantially cylindrical shape with a vertical axis B-B′. Thus it comprises a bottom wall 80, a peripheral side wall 82 and an upper wall 84, the walls 80, 82 and 84 interiorly delimiting the space 78.

The inner space of each casing 70 is for example comprised between 300 m³ and 500 m³.

The casing 70 further comprises a tapping 85A for injecting liquid or solid into the space 78 and a tapping 85B for purging the space 78 opening out into the inner space 78 above the injection tapping 85A.

The tappings 85A, 85B are provided with valves for selectively obturating access to the space 78.

The adjustment member 72 is attached on the casing 70.

It has a maximum transverse dimension, taken horizontally in FIG. 2, of less than the minimum transverse dimension of the casing 70.

The member 72 includes in this example a first tubular element 86 fixedly mounted in the casing 70 through the inner space 78 between the lower wall 80 and the upper wall 84 and a lower tubular element 88, deployable from the fixed element 86 before or during the installation of the supporting foundation 20, in order to adjust the vertical position of the casing 70 above the floor 12 of the body of water.

In this example, the fixed element 86 and the moveable element 88 are formed by telescopic tubes slideably mounted into each other along a vertical axis.

The deployable element 88 is displaceable relatively to the fixed element 86 in order to protrude downwards beyond the casing 70 between a retracted position in the casing 70, illustrated in FIG. 3, and a plurality of deployed positions under the casing 70 at a selected height.

During the installation of the supporting foundation 20, the deployable element 88 is temporarily or permanently immobilized in a selected deployed position relatively to the fixed elements 86 and relatively to the casing 70, in order to maintain the casing 70 in a selected vertical position relatively to the floor 12 of the body of water.

This vertical position is for example comprised between 0.5 m and 5 m above the floor 12.

The immobilization of the fixed element 86 relatively to the deployable element 88 is for example ensured by welding, screwing or riveting or by plastic deformation.

The presence of the adjustment member 72 on the different legs 52 allows adjustment of the height of each adjustment member 72 which protrudes under the casing 70 between the lower wall 80 and the engaging member 74, depending on the depth of the floor 12 facing the leg 52.

Thus, regardless of the topography of the floor 12 of the body of water 14, the casing 70 may be maintained with their bottom walls 80 substantially in a selected vertical position so that the base 50 and the support 56 have a determined orientation in a horizontal plane and in a vertical plane.

In the example illustrated in the figures, the base 50 is maintained substantially horizontal, the casings 70 all being substantially positioned at the same depth relatively to the surface of the body of water 14.

For this purpose, as illustrated in FIG. 2, the protruding height of the adjustment members 72 between the casing 70 and the engaging member 74 may be different from one leg 52 to the other. This height is for example comprised between 1/10 and 1 time the height of the casing 70.

Thus, the supporting foundation 20 comprises at least two adjustment members 72 which have different protruding heights under their casing 70.

The engaging member 74 has a maximum transverse dimension, taken horizontally in FIG. 2, greater than the maximum transverse dimension of the rigid adjustment member 72.

In the example illustrated in FIGS. 1 to 4, the engaging member 74 is formed by a shoe 90 attached to the lower end of the adjustment member 72.

The shoe 90 is positioned bearing upon the floor 12 of the body of water. It has a solid and convex lower surface 92 with convexity directed downwards in order to prevent or at least limit the sinking of the leg 52 into the floor 12, notably if this floor 12 is soft.

In an alternative, illustrated in FIG. 5, the shoe 90 is formed by a cone pointing downwards delimiting a solid lower surface 92. Such a conical shoe 90 is notably adapted to a floor 12 consisting of or comprising a large amount of rocks 94.

In the alternatives illustrated in FIGS. 6 and 7, the engaging member 74 is formed by a hollow receptacle 94 turned upside down delimiting a cavity 96 for receiving the floor 12.

The cavity 96 opens out downwards in order to allow the sinking of the receptacle 94 into the floor 12. In the example illustrated in FIG. 6, the height of the receptacle 94 is advantageously relatively small, for example less than the height of the casing 70.

Further, the hollow wall delimiting the receptacle 94 is solid facing the space 98 delimited between the receptacle 94 and the floor 12 in the cavity 96.

In the alternative illustrated in FIG. 7, the receptacle 94 comprises a tapping 100 opening out into the space 98 through an upper region of the hollow wall forming the receptacle 94. The tapping 100 is intended to be connected to a pump in order to suck up fluid present in the space 98 and to sink the receptacle 94 into the floor 12 which forms a suction anchor.

The height of the receptacle 94 is then advantageously greater than that of the casing 70.

In the alternative illustrated in FIG. 8, the engaging member 74 is formed by a mass 102 of cement which is injected through the upper tubular element 86 and through the lower tubular element 88, the end of which is introduced beforehand by drilling into the floor 12 of the body of water 14. The body 102 extends around the lower tubular element 88 between its lower end and the body of water 14.

According to the different soil compositions forming the floor 12 facing the legs 52, an engaging member 74 adapted to the nature of the soil below the leg 52 is therefore used.

The supporting foundation 20 may therefore comprise legs 52 having engaging members 74 of distinct structures. With this it is possible to ensure good, notably horizontal, stability of the supporting foundation 20 on the floor 12 of the body of water 14.

In an alternative illustrated in FIG. 9, the casing 70 is open upwards along the upper edge of the side wall 82. It is thus without any upper wall 84 above the side wall 82. The inner space 78 may be filled with liquid and/or solid ballast via the opening of the casing 70 located above the side wall 82.

With reference to FIG. 1, the hydrokinetic turbine support 54 comprises a substantially cylindrical nacelle 110 and a sleeve 112 for guiding the attachment stud 26 inserted into the nacelle 110.

The nacelle 110 is formed by a hollow wall opening out upwards. It extends along a nacelle axis C-C′ which, in this example is vertical and substantially passes close to the centroid of the base 50.

The frame members 60A connecting the support 54 to each leg 52 are attached on the outer surface of the nacelle 110 while being angularly distributed around the axis of the nacelle.

The guiding sleeve 112 is positioned in the nacelle 110. It includes a lower region 114 intended to receive the lower portion 44 of the stud 26 and an upper region 116 divergent upwards for supporting the intermediate convergent portion 42 of the stud 26.

The sleeve 112 further delimits a vertical slot 118 for receiving the indexation rib 46, the slot 118 opening out upwards through a divergent cavity 120 for guiding the groove 46 towards the slot 118.

The lower region 114 delimits a cylindrical central cavity with a substantially conjugate transverse section to the cross-section of the lower portion 44.

The upper region 116 also delimits a central cavity divergent upwards, and having a shape mating the shape of the intermediate portion 42.

The slot 118 extends through the lower region 114 and partly through the upper region 116. It has a width conjugate to that of the rib 46 for blocking rotation of the stud 26 around the axis C-C′ when the rib 46 is received in the slot 118.

The divergent cavity 120 is made in the upper region 116 at the upper end of the slot 118.

When the hydrokinetic turbine 22 is attached onto the supporting foundation 20, the stud 26 has been partly introduced into the nacelle 110. The lower portion 44 is housed in the lower region 114 and the intermediate portion 42 rests on the upper region 116.

The rib 46 is angularly immobilized in the slot 118 ensuring angular indexation of the hydrokinetic turbine 22 in a determined position around the axis C-C′.

A first method for placing a device 10 for generating electric power according to the invention is illustrated by FIGS. 12 and 13.

This method is applied by means of a laying ship 130 provided with hoists 132, such as cranes. The hoists 132 have deployable lines 133 capable of moving the device 10 down into the body of water 14.

This method comprises a step for transporting the supporting foundation 20 at the surface of the body of water 14 as far as a point located facing a region 134 for laying this foundation on the floor 12 of a body of water 14.

The method then comprises a step for totally immersing the supporting foundation 20 into the body of water 14 from the laying ship 130, and a step for positioning the supporting foundation 20 bearing upon the floor 12 of the body of water 14.

Initially, in the transport step, the supporting foundation 20 is loaded on the ship 130. As illustrated in FIG. 3, the members 72 for adjusting the legs 52 are retracted in the casing 70 so that the vertical congestion of the supporting foundation 20 is minimum.

For this purpose, the lower tubular elements 88 are maintained in the retracted position in the upper tubular elements 86. The engaging members 74 are maintained close to the casings 70.

In a first alternative of the method, the topography of the laying region 134 is determined before setting the supporting foundation 20 into place.

Thus, the height of each adjustment member 72 protruding under the casing 70 is calculated for each leg 52 according to the determined topography in order to maintain the base 50 in a determined orientation relatively to a vertical plane and relatively to a horizontal plane on the floor 12 of the stretch of water 14.

The adjustment members 72 are then deployed at the surface for each leg 52, by adjusting their height according to the calculated height values for each leg 52.

Next, the lower tubular elements 88 are immobilized at the determined height on the upper tubular elements 86 by welding or by plastic deformation at the surface of the body of water, for example on the laying ship 130.

Actuation lines 133 are then attached on the attachment members 76 and the cranes 132 are maneuvered in order to extract the supporting foundation 20 from out of the ship 130 and place it facing the laying region 134 above or partly immersed in the body of water 14.

A selected amount of solid and/or liquid ballast is then introduced into the inner space 78 of each casing 70 and the supporting foundation 20 is moved down into the body of water 14.

In the example illustrated in FIG. 12, the hydrokinetic turbine 22 is mounted beforehand on its support 54 by introducing the attachment stud 26 into the nacelle 110 as described earlier.

Alternatively, the supporting foundation 20 is moved down and laid on the floor 12 before the hydrokinetic turbine 22, the hydrokinetic turbine 22 then being moved down into the body of water 14 after having positioned the supporting foundation 20 on the floor 12.

Next, in the immersion step, the supporting foundation 20 is totally immersed into the body of water 14 and is then moved down as far as the region 134 while being hung on the lines 133 for positioning engaging members 74 in contact with the floor 12 of the body of water.

Taking into account the presence of members 72 for adjusting adequate heights for each leg 52 and of preselected engaging members 74 for adapting to the nature of the soil making up the floor 12, the supporting foundation 20 is positioned very accurately and robustly on the floor 12 of the body of water 14.

This is achieved without it being necessary to carry out significant earthmoving work, and by a laying method which is very simple to apply.

The cost of the laying of the supporting foundation 20 and of the device 10 is therefore reduced and the laying operation is facilitated.

Next, the lines 133 are detached from the attachment members 76 and are brought back up to the laying ship 130. The hydrokinetic turbine 22 is then able to operate and to produce electric power under the effect of the rotation of the turbine 28, via the alternator 30.

In an alternative of the method, the supporting foundation 20 is moved down while maintaining the adjustment members 72 retracted.

Next, when the supporting foundation 20 reaches a position selected with at least one leg 52 located away from the floor 12 of the body of water, the lower tubular elements 88 are released so as to deploy towards the floor 12 of the body of water until the engaging member 74 comes into contact with the floor 12.

When the positioning of the supporting foundation 20 is satisfactory, the lower elements 88 are immobilized relatively to the upper elements 86, for example by plastic deformation and the lines 133 are brought back up.

A second placement method according to the invention is illustrated in FIGS. 14 to 16.

Unlike the first method described in FIGS. 12 and 13, the inner space 78 of the floatability casing 70 is filled with a sufficient amount of gas for ensuring sufficient floatability of the supporting foundation 20 in order to maintain it partly immersed at the surface of the body of water 14, under the effect of its own floatability.

As illustrated in FIG. 14, this specific floatability is also sufficient for maintaining the hydrokinetic turbine 22 above the surface of the body of water when this hydrokinetic turbine 22 is initially borne by the supporting foundation 20.

In the transport step illustrated in FIG. 14, the laying ship 130 then tows the supporting foundation 20 partly immersed in the body of water 14 by means of a traction line 140 as far as a point located facing the implantation region 134.

Therefore it is not necessary that the ship 130 be provided with hoists 132 of high load capacity, able to allow the lifting of the supporting foundation 20.

Next, when the supporting foundation 20 reaches the aforementioned point, located facing the implantation region 134, float lines 142 provided with buoys 144 distributed over their length are attached on each attachment element 74, in order to maintain the position of the supporting foundation 20 horizontal at the beginning of its immersion.

The tappings for injecting fluid 85A of each casing 70 are opened in order to inject liquid or solid ballast into the inner space 78, as a replacement for at least one portion of the gas present in this space 78.

The floatability of the supporting foundation 20 decreases, which causes its total immersion in the vicinity of the surface.

As illustrated by FIG. 16, the ship 130 is then placed above the supporting foundation 20. A descent line 146 deployed by means of a winch from the ship 130 is then connected onto the attachment member 76 and the float lines 142 may be detached from the attachment members 76.

The supporting foundation 20 is then gradually lowered by the descent line 146 as far as the region 134, in order to position the legs 52 bearing upon the floor 12 of the body of water as described earlier.

In an alternative, the immersion of the supporting foundation 20 and its deposition onto the floor 12 are exclusively carried out by means of float lines 142 without using a descent line 146 from the ship 130.

The immersion of the supporting foundation 20 is then automatically controlled by the buoys 144 present on the float lines 142.

In all the cases as described earlier, the adjustment members 72 may be deployed either before lowering the supporting foundation 20 into the body of water 14, if the topography of the region 134 has been studied beforehand, or as an alternative, when the supporting foundation 20 is positioned in the body of water 14 in the vicinity of the region 134 with at least one leg away from the floor 12.

Claims

1. A supporting foundation for a hydrokinetic turbine, intended to be laid on the floor of a body of water, the supporting foundation comprising: a base;a hydrokinetic turbine carrier supported by the base,at least three legs for bearing on the floor of the body of water, connected together by means of the base, each bearing leg including a hollow casing,characterized in that each bearing leg further comprises:a rigid member for adjusting the vertical position of the casing relatively to the floor of the body of water, the rigid adjustment member being immobilized so as to protrude vertically under the casing;a member for engaging with the floor of the body of water, rigidly connected to the lower end of the rigid adjustment member.

2. The supporting foundation according to claim 1, wherein at least two of the adjustment members have different heights, taken between the casing and the engaging member.

3. The supporting foundation according to claim 1, wherein each adjustment member comprises an element which may be deployed towards the floor of the body of water relatively to the casing before installing the supporting foundation on the floor of the body of water.

4. The supporting foundation according to claim 3, wherein each adjustment member comprises a fixed element relatively to the casing, the deployable element being moveably mounted relatively to the fixed element before installing the supporting foundation on the floor of the body of water, the fixed element and the deployable element being in particular formed by telescopic tubes.

5. The supporting foundation according to claim 1, wherein each casing comprises at least one bottom wall and a side wall delimiting an interior space able to be filled with gas for ensuring floatability specific to the supporting foundation on the body of water.

6. The supporting foundation according to claim 5, wherein the casing comprises an upper wall obturating upwards the inner space the casing including at least one tapping for injecting and/or purging fluid in the inner space.

7. The supporting foundation according to claim 5, wherein the inner space permanently opens out upwards above the side wall.

8. The supporting foundation according to claim 1, wherein at least one of the engaging members delimits a cavity opening downwards, intended to be inserted into the floor of the body of water.

9. The supporting foundation according to claim 8, wherein the cavity is delimited by a hollow receptacle opening downwards and having an upper obturation wall towards the top of the cavity.

10. The supporting foundation according to claim 1, wherein at least one of the engaging members comprises a totally solid, in particular convex, lower surface for opposing penetration of the engaging member into the floor of the body of water.

11. An underwater device for generating electric power, comprising: a supporting foundation according to claim 1,a hydrokinetic turbine mounted on the hydrokinetic turbine support.

12. A method for setting into place a supporting foundation according to claim 1, comprising the following steps: transporting the supporting foundation at least partly above the surface of the body of water as far as point located facing a laying region for the supporting foundation on the floor of the body of water;totally immersing the supporting foundation in the body of water;positioning the legs of the supporting foundation bearing upon the laying region, each engaging member being placed in contact with the floor of the body of water.

13. The method according to claim 12, comprising a step for adjusting the protruding height of each rigid adjustment member under the casing, and then a step for immobilizing each rigid adjustment member relatively to the casing.

14. The method according to claim 13, wherein the step for adjusting the height of each protruding rigid adjustment member under the casing is carried out before total immersion of the supporting foundation in the body of water.

15. The method according to claim 1, wherein the transport step is achieved by maintaining the supporting foundation partly immersed in the body of water under the effect of its own floatability.