Technical Field

The present disclosure relates to a tidal turbine including a nacelle and a seabed support structure, and, in particular, but not limited to, a tidal turbine including a nacelle and an asymmetrical seabed support structure.

Background

Known tidal turbines include tidal blades connected a nacelle which comprises a generator. The tidal turbine is placed underwater such that the tidal blades may be rotated by currents in the water so as to produce electricity by the generator.

In certain tidal turbines, the tidal turbine is placed on the seabed and anchored thereto so as to prevent movement of the tidal turbine. The means for connecting the tidal turbine to the seabed must be structurally formed to transfer the forces imparted on the tidal turbine from the current in the water. As the currents in the water can be very strong, the connection means are typically reinforced and can form heavy and expensive parts of known tidal turbines.

In view of the above, there is a need for a tidal turbine in which the connection means for anchoring the tidal turbine to the seabed can be made more structurally efficient.

Summary of the Disclosure

Accordingly, it is an object of the present disclosure to provide a tidal turbine in which the connection means for anchoring the tidal turbine to the seabed can be made more structurally efficient.

These objectives and others are achieved with the devices of Claims 1, 16 and 21. Preferred embodiments are recited in the dependent claims. In an aspect of the present disclosure, there is provided a tidal turbine including a nacelle and a seabed support structure for supporting the tidal turbine on the seabed, the seabed support structure comprises: a central tower extending downwardly from the nacelle, the central tower defining a longitudinal axis; and at least three supporting arms each being arranged to extend at least radially outwardly from the central tower, and being anchorable to the seabed, wherein the at least three supporting arms are disposed about the central tower such that a first pair of neighbouring supporting arms of said at least three supporting arms define a first angular spacing around the longitudinal axis of the central tower; and a second pair of neighbouring supporting arms of said at least three supporting arms define a second angular spacing around the longitudinal axis of the central tower, and wherein the magnitudes of the respective first and second angular spacings are non-equal.

In known tidal turbines, any supporting arms are disposed about a tower with equal angular spacings. For example, known tidal turbines may comprise three supporting arms which are each angularly spaced apart by 120 degrees around a tower which extends from the nacelle.

With the above-noted configurations of the present disclosure, as the first angular spacing and the second angular spacing are non-equal, the forces on the tidal blades may be more efficiently transferred to the seabed. Specifically, as the forces acting on the tidal blades tend to act along a particular direction, an asymmetrical support structure is better able to counter such directional forces. Therefore, the above-noted configurations of the present disclosure provide for an improved connection means for anchoring the tidal turbine to the seabed which can be made more structurally efficient.

In certain embodiments, each one/at least one of the at least three supporting arms is elongate in shape. In certain embodiments, each one/at least one of the at least three supporting arms each comprises a generally elongate arm element extending generally along the direction in which the respective supporting arm extends from the central tower. In certain embodiments, the elongate arm element forms the majority of the length of the respective supporting arm. In certain embodiments, the elongate arm element is generally straight. In certain embodiments, the elongate arm extends along the entire length of the respective supporting arm.

In certain embodiments, each one/at least one of the at least three supporting arms extends outwardly from the central tower in generally a single direction. In certain embodiments, the single direction consists of a single radial component direction relative to the central tower and a single longitudinal component direction relative to the central tower. In other words, each one/at least one of the at least three supporting arms generally does not extend outwardly from the central tower along multiple directions.

In certain embodiments, each one/at least one of the at least three supporting arms is arranged to extend radially outwardly from the central tower and longitudinally outwardly from the central tower.

In certain embodiments, each one/at least one of the at least three supporting arms comprises a bend therein.

As would be understood by the skilled person, the definitions used throughout this disclosure to define the relative arrangements of the supporting arms is to refer to all supporting arms of a given tidal turbine. In particular, the term "at least three supporting arms” and the arrangements thereof may refer to all supporting arms of the tidal turbine.

As used herein, the term 'supporting arm’ may refer to an element which can resist both tension and compression.

In certain embodiments, the radially outermost ends of two of said at least three supporting arms each lie on a notional line which intersects the plane defined by tidal blades of the tidal turbine. The angle between said notional line and said tidal blade plane lies in the range of about 80 degrees to about 100 degrees. The angle between said notional line and said tidal blade plane may lie in the range of about 85 degrees to about 95 degrees. As used herein, the plane defined by tidal blades of the tidal turbine refers to the plane in which the tidal blades rotate in.

Throughout this disclosure, the radially outermost end of any supporting arm may also be the section of the supporting arm which is configured to be in contact with/on the seabed when the tidal turbine is in use. The radially outermost end of any supporting arm may be the only section of the supporting arm which is configured to be in contact with/on the seabed when the tidal turbine is in use.

In certain embodiments, each one/at least one of the at least three supporting arms comprises a contact section configured to be in contact with/on the seabed when the tidal turbine is in use. In certain embodiments, each one/at least one of the at least three supporting arms comprises exactly one contact section configured to be in contact with/on the seabed when the tidal turbine is in use. In certain embodiments, the contact section is an anchor configured to be placed within the seabed.

In certain embodiments, the contact section of two of said at least three supporting arms each lie on a notional line which intersects the plane defined by tidal blades of the tidal turbine. The angle between said notional line and said tidal blade plane lies in the range of about 80 degrees to about 100 degrees. The angle between said notional line and said tidal blade plane may lie in the range of about 85 degrees to about 95 degrees.

In certain embodiments, the radially outermost ends of two of said at least three supporting arms each lie on a notional line which intersects the plane defined by tidal blades of the tidal turbine. The angle between said notional line and said tidal blade plane lies in the range of about 80 degrees to about 100 degrees. The angle between said notional line and said tidal blade plane may lie in the range of about 85 degrees to about 95 degrees.

In such embodiments, as the current in the water imparts forces largely in a direction perpendicular to the plane of the tidal blades, having two supporting arms arranged in such a manner allows for a support structure that is further able to counter the current forces efficiently. Therefore, the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, the angle between said notional line and said tidal blade plane is about 90 degrees.

In such embodiments, as the current in the water imparts forces largely in a direction perpendicular to the plane of the tidal blades, having two supporting arms arranged in such a manner allows for a support structure that is further able to counter the current forces efficiently. Therefore, the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, the radially outermost end of each one/at least one of the at least three supporting arms is configured to be placed, in use, on or in contact with the seabed. In certain embodiments, the radially outermost end of each one/at least one of the at least three supporting arms is the only part of the respective supporting arm which is configured to be placed, in use, on or in contact with the seabed.

In certain embodiments, the said two supporting arms are each longer than another supporting arm of the at least three supporting arms. In certain embodiments, the said two supporting arms are longer than each of the remaining supporting arms of the at least three supporting arms. In certain embodiments, the said two supporting arms are each about 1.2 to about 2.0 times greater in length than another supporting arm of the at least three supporting arms. In certain embodiments, the said two supporting arms are each about 1.2 to about 2.0 times greater in length than each of the remaining supporting arms of the at least three supporting arms.

In such embodiments, as the current in the water imparts forces largely in a direction perpendicular to the plane of the tidal blades, having two supporting arms arranged in such a manner and being longer in length allows for the two supporting arms to provide a greater force countering the forces caused by the currents. This allows for a support structure that is further able to counter the current forces efficiently. Therefore, the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, the radially outermost ends/contact sections of said two supporting arms are each at a greater radial distance from the central tower than the radially outermost ends/contact section of another supporting arm of the at least three supporting arms. In certain embodiments, the radially outermost ends/contact sections of said two supporting arms are each at a greater radial distance from the central tower than the radially outermost ends/contact section of the remaining supporting arms of the at least three supporting arms. In certain embodiments, the radially outermost ends/contact sections of said two supporting arms are each about 1.2 to about 2.0 times greater in radial distance from the central tower than the radially outermost ends/contact section of another supporting arm of the at least three supporting arms. In certain embodiments, the radially outermost ends/contact sections of said two supporting arms are each about 1.2 to about 2.0 times greater in radial distance from the central tower than the radially outermost ends/contact section of the remaining supporting arms of the at least three supporting arms.

In certain embodiments, the two of said at least three supporting arms each extend outwardly from the central tower along a radial direction by a substantially equal distance.

With such configurations, the two supporting arms can provide largely balanced structural support when the current is following in either direction relative to the tidal blades. Therefore, the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, the radially outermost ends/contact sections of two supporting arms of said at least three supporting arms each extend outwardly from the central tower along a radial direction by a substantially equal distance. In certain embodiments, the angular spacing between said two supporting arms is greater than the angular spacing between another pair of neighbouring supporting arms. In certain embodiments, the angular spacing between said two supporting arms is between about 130 degrees to about 160 degrees.

In certain embodiments, the angular spacing between said two supporting arms is greater than the angular spacing between each and every other pair of neighbouring supporting arms.

In certain embodiments, the tidal turbine consists of three supporting arms. In such embodiments, the angular spacing between said two supporting arms is between about 130 degrees to about 160 degrees. In such embodiments, the angular spacing between the other two pairs of neighbouring supporting arms is between about 100 degrees to about 115 degrees.

In such embodiments, as the current in the water imparts forces largely in a direction perpendicular to the plane of the tidal blades, having two supporting arms arranged in such a manner and being angularly spaced apart by a greater amount allows for the two supporting arms to provide a greater force countering the forces caused by the currents. This allows for a support structure that is further able to counter the current forces efficiently. Therefore, the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, at least one of said at least three supporting arms extends radially outwardly from the central tower along a radial direction which is substantially parallel to the plane defined by tidal blades of the tidal turbine.

In such embodiments, any forces acting on the tidal turbine in a direction which is not perpendicular to the plane of the tidal turbines can be efficiently countered by the supporting arm extending parallel to the tidal blade plane. This allows for a support structure that is further able to counter the current forces efficiently. Therefore, the above- noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, at least one/all of said at least three supporting arms extend towards the seabed when in use.

In certain embodiments, at least one of said at least three supporting arms extends directly from the central tower.

In such embodiments, the material used to construct the supporting structure is minimised and therefore the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, all of said at least three supporting arms extends directly from the central tower.

In such embodiments, the material used to construct the supporting structure is minimised and therefore the above-noted configurations provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, at least one of said at least three supporting arms is arranged to extend outwardly from the central tower along an axis. The angle between said axis and said longitudinal axis of the central tower being greater or less than, but not equal to, 90 degrees.

In such embodiments, the at least three supporting arms each extend both radially outwardly from the central tower and downwardly from the central tower. With such configurations, the bottom of the central tower may be raised above the seabed when in use. Such arrangements provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, the tidal turbine consists of three supporting arms.

Such configurations provide for the lowest number of supporting arms which still provide for sufficient support of the tidal turbine. Accordingly, such arrangements provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient.

In certain embodiments, each supporting arm is of a different length.

Such configurations are particularly suited for situations in which the directions of flow of the current are not directly opposite. Such arrangements provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient for such flow conditions.

In certain embodiments, at least two supporting arms are of the same length.

Such configurations are particularly suited for situations in which the directions of flow of the current are largely opposite. Such arrangements provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient for such flow conditions.

In certain embodiments, at least two supporting arms are longer than the remaining supporting arm(s).

Such configurations allow the two arms to be placed in a direction countering the flow of current. Such arrangements provide for a further improved connection means for anchoring the tidal turbine to the seabed which can be made even more structurally efficient. In certain embodiments, the seabed support structure is a gravity base.

In certain embodiments, the radially outermost end of each one of/at least one of the three supporting arm comprises a block weight. In certain embodiments, the block weight forms the majority of the overall weight of the respective supporting arm. In certain embodiments, the block weight may be shaped as a cuboid, and, optionally a rectangular cuboid.

In certain embodiments, the tidal blades are configured such that they rotate around a common rotation axis in the same direction regardless of the direction of current. In other words, both ebb and flow currents result in rotation of the two tidal blades in the same direction/sense around the common rotation axis.

In certain embodiments, the tidal turbine is a unidirectional tidal turbine.

In another aspect of the present disclosure, there is provided a tidal turbine including a nacelle and a seabed support structure for supporting the tidal turbine on the seabed, the seabed support structure comprising: a central tower extending downwardly from the nacelle, the central tower defining a longitudinal axis; and at least three supporting arms each being arranged to extend at least radially outwardly from the central tower, and being anchorable to the seabed, wherein the masses of two of the at least three supporting arms are non-equal.

In known tidal turbines, any supporting arms are of the same mass. With the above-noted configurations of the present disclosure, as at least two of the supporting arms have different masses, the forces on the tidal blades may be more efficiently transferred to the seabed. Specifically, as the forces acting on the tidal blades tend to act along a particular direction, an asymmetrical mass distribution of the support structure is better able to counter such directional forces. Therefore, the above-noted configurations of the present disclosure provide for an improved connection means for anchoring the tidal turbine to the seabed which can be made more structurally efficient. In certain embodiments, a first supporting arm of the at least three supporting arms and a second supporting arm of the at least three supporting arms each have a mass which is greater than a third supporting arm of the at least three supporting arms. In certain embodiments, the radially outermost ends of the first supporting arm and the second supporting arm each lie on a notional line which intersects the plane defined by tidal blades of the tidal turbine, the angle between said notional line and said tidal blade plane lies in the range of: about 80 degrees to about 100 degrees; or about 85 degrees to about 95 degrees, preferably about 90 degrees.

In certain embodiments, the third supporting arm extends radially outwardly from the central tower along a radial direction which is substantially parallel to a plane defined by tidal blades of the tidal turbine.

In certain embodiments, each of the at least three supporting arms comprises a block weight, and wherein the respective block weights of the two of the at least three supporting arms are non-equal such that the masses of two of the at least three supporting arms are non-equal. In certain embodiments, the block weights form the majority of the overall weight of the respective supporting arm. In certain embodiments, the block weights are disposed at the radially outermost end of the respective supporting arm.

In certain embodiments, the at least three supporting arms are disposed about the central tower such that neighbouring supporting arms therebetween define angular spacings around the longitudinal axis of the central tower, where all of the angular spacings between each neighbouring pairs are generally equal. In certain embodiments, the lengths of each of the at least three supporting arms are generally equal.

In another aspect of the present invention, there is provided a tidal turbine including a nacelle and a seabed support structure for supporting the tidal turbine on the seabed, the seabed support structure comprising: a central tower extending downwardly from the nacelle, the central tower defining a longitudinal axis; and at least three supporting arms each being arranged to extend at least radially outwardly from the central tower, and being anchorable to the seabed, wherein the lengths of two of the at least three supporting arms are non-equal.

In known tidal turbines, any supporting arms are of the same length. With the above-noted configurations of the present disclosure, as at least two of the supporting arms have different lengths, the forces on the tidal blades may be more efficiently transferred to the seabed. Specifically, as the forces acting on the tidal blades tend to act along a particular direction, an asymmetrical length of the support structure is better able to counter such directional forces. Therefore, the above-noted configurations of the present disclosure provide for an improved connection means for anchoring the tidal turbine to the seabed which can be made more structurally efficient.

In certain embodiments, a first supporting arm of the at least three supporting arms and a second supporting arm of the at least three supporting arms each have a length which is greater than a third supporting arm of the at least three supporting arms. In certain embodiments, the radially outermost ends of the first supporting arm and the second supporting arm each lie on a notional line which intersects the plane defined by tidal blades of the tidal turbine, the angle between said notional line and said tidal blade plane lies in the range of: about 80 degrees to about 100 degrees; or about 85 degrees to about 95 degrees, preferably about 90 degrees.

In certain embodiments, the third supporting arm extends radially outwardly from the central tower along a radial direction which is substantially parallel to a plane defined by tidal blades of the tidal turbine.

In certain embodiments, the first supporting arm and the second supporting arm are each about 1.2 to about 2.0 times greater in length than the third supporting arm.

In certain embodiments, the at least three supporting arms are disposed about the central tower such that neighbouring supporting arms therebetween define angular spacings around the longitudinal axis of the central tower, where all of the angular spacings between each neighbouring pairs are generally equal. In certain embodiments, the masses of each of the at least three supporting arms are generally equal. The above three aspects and their specifics embodiments can be freely combined as will be evident from the below detailed description.

In particular, there is also provided a tidal turbine including a nacelle and a seabed support structure for supporting the tidal turbine on the seabed, the seabed support structure comprising: a central tower extending downwardly from the nacelle, the central tower defining a longitudinal axis; and at least three supporting arms each being arranged to extend at least radially outwardly from the central tower, and being anchorable to the seabed, wherein the at least three supporting arms are disposed about the central tower such that a first pair of neighbouring supporting arms of said at least three supporting arms define a first angular spacing around the longitudinal axis of the central tower; and a second pair of neighbouring supporting arms of said at least three supporting arms define a second angular spacing around the longitudinal axis of the central tower, wherein the magnitudes of the respective first and second angular spacings are non-equal, and wherein the masses of two of the at least three supporting arms are non-equal.

There is also provided a tidal turbine including a nacelle and a seabed support structure for supporting the tidal turbine on the seabed, the seabed support structure comprising: a central tower extending downwardly from the nacelle, the central tower defining a longitudinal axis; and at least three supporting arms each being arranged to extend at least radially outwardly from the central tower, and being anchorable to the seabed, wherein the at least three supporting arms are disposed about the central tower such that a first pair of neighbouring supporting arms of said at least three supporting arms define a first angular spacing around the longitudinal axis of the central tower; and a second pair of neighbouring supporting arms of said at least three supporting arms define a second angular spacing around the longitudinal axis of the central tower, wherein the magnitudes of the respective first and second angular spacings are non-equal, and wherein the lengths of two of the at least three supporting arms are non-equal.

There is also provided a tidal turbine including a nacelle and a seabed support structure for supporting the tidal turbine on the seabed, the seabed support structure comprising: a central tower extending downwardly from the nacelle, the central tower defining a longitudinal axis; and at least three supporting arms each being arranged to extend at least radially outwardly from the central tower, and being anchorable to the seabed, wherein the masses of two of the at least three supporting arms are non-equal, and wherein the lengths of two of the at least three supporting arms are non-equal. In certain embodiments, the two supporting arms of non-equal masses are the same two supporting arms of non-equal lengths.

As used herein, angular spacings of two supporting arms refers to the angle of intersection of the notional lines along their direction of extension from the central tower.

As used throughout herein, the terms 'upwardly’, 'downwardly’, 'outwardly’, 'inwardly’, 'below’, 'above’, 'horizontal’ and 'vertical’ refer to their usual meanings understood by the skilled person when the tidal turbine is in use and being anchored to the seabed.

Brief Description of the Drawings

For a better understanding of the present disclosure and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

Figure 1 shows a perspective view of a tidal turbine including a nacelle and seabed support structure;

Figure 2 shows a top plan view of the tidal turbine of Figure 1; and

Figure 3 shows a side view of the tidal turbine of Figures 1 and 2.

Detailed Description

Figure 1 shows a perspective view of a tidal turbine 100. The tidal turbine 100 is for being placed underwater such that the tidal turbine 100 is able to produce electricity due to the currents in the water. The tidal turbine 100 comprises a nacelle 110 which has, amongst other things, a generator therein (not shown). Two tidal blades 120a, 120b are rotationally coupled to the generator such that rotation of the two tidal blades around a common rotation axis generates electricity via the generator.

The two tidal blades 120a, 120b are each configured such that a current flowing in a direction intersecting the face of the respective blade effects a force on the respective blade such that it rotates about the rotation axis. For example, such currents may be in the direction of the arrows C which represents the direction of currents in certain situations.

The two tidal blades 120a, 120b each rotate in a common plane, namely the tidal blade rotation plane P (see Figure 2). The tidal blade rotation plane P is perpendicular to the current directions C.

In certain embodiments, the two tidal blades 120a, 120b are configured such that they rotate around the common rotation axis in the same direction regardless of the direction of current along directions C. In other words, both ebb and flow currents result in rotation of the two tidal blades 120a, 120b in the same direction/sense around the common rotation axis. Accordingly, in certain embodiments, the tidal turbine 100 is a unidirectional tidal turbine.

The tidal turbine 100 further comprises a seabed support structure which is configured to support the tidal turbine on the seabed. The seabed support structure comprises a central tower 130 and a support arm structure 140.

The central tower 130 extends downwardly from the nacelle 110. The central tower 130 defines a longitudinal axis. As shown in Figure 1, the central tower 130 is elongate and generally cylindrical. The longitudinal axis of the central tower 130 is configured to be generally perpendicular to the seabed when the tidal turbine 100 is in use. The longitudinal axis of the central tower 130 is configured to be generally parallel to the tidal blade rotation plane P. The support arm structure 140 extends from the lower portion of the central tower 130. The support arm structure 140 comprises three supporting arms 141, 142, 143. Each one of the three supporting arms 141, 142, 143 is anchorable to the seabed.

Each one of the three supporting arms 141, 142, 143 extends outwardly from the central tower 130.

First supporting arm 141 extends outwardly from the central tower 130. The first supporting arm 141 extends outwardly away from the central tower 130 generally along a single direction. Said general direction of the first supporting arm 141 comprises a radial component relative to the central tower 130 and a longitudinal component relative to the central tower 130. As can be seen in Figure 3, first supporting arm 141 extends radially and downwardly from the central tower 130.

Similarly, second supporting arm 142 extends outwardly from the central tower 130. The second supporting arm 142 extends outwardly away from the central tower 130 generally along a single direction. Said general direction of the second supporting arm 142 being different from said general direction of the first supporting arm 141. Said general direction of the second supporting arm 142 comprises a radial component relative to the central tower 130 and a longitudinal component relative to the central tower 130. As can be seen in Figure 3, second supporting arm 142 extends radially and downwardly from the central tower 130.

Similarly, third supporting arm 143 extends outwardly from the central tower 130. The third supporting arm 143 extends outwardly away from the central tower 130 generally along a single direction. Said general direction of the third supporting arm 143 being different from said general direction of the first supporting arm 141 and the second supporting arm 142. Said general direction of the third supporting arm 143 comprises a radial component relative to the central tower 130 and a longitudinal component relative to the central tower 130. As can be seen in Figure 3, third supporting arm 143 extends radially and downwardly from the central tower 130. The first supporting arm 141 comprises an elongate arm element 141a. The elongate arm element 141a extends along the length of the first supporting arm 141. The elongate arm element 141a extends in the general direction in which the first supporting arm 141 extends outwardly away from the central tower 130. The first supporting arm 141 further comprises a block weight 141b. The block weight 141b is disposed at a distal portion of the first supporting arm 141.

Similarly, the second supporting arm 142 comprises an elongate arm element 142a. The elongate arm element 142a extends along the length of the second supporting arm 142. The elongate arm element 142a extends in the general direction in which the second supporting arm 142 extends outwardly away from the central tower 130. The second supporting arm

142 further comprises a block weight 142b. The block weight 142b is disposed at a distal portion of the second supporting arm 142.

Similarly, the third supporting arm 143 comprises an elongate arm element 143a. The elongate arm element 143a extends along the length of the third supporting arm 143. The elongate arm element 143a extends in the general direction in which the third supporting arm 143 extends outwardly away from the central tower 130. The third supporting arm

143 further comprises a block weight 143b. The block weight 143b is disposed at a distal portion of the third supporting arm 143.

Each one of the three supporting arms 141, 142, 143 is configured to be placed on or in contact with the seabed. In particular, the distal end of each of the three supporting arms 141, 142, 143 is configured to be placed on or in contact with the seabed. As shown in Figure 3, each of the three supporting arms 141, 142, 143 comprises a seabed penetrating anchor 141c, 142c, 143c, respectively. The seabed penetrating anchors 141c, 142c, 143c are disposed at the distal portion of the respective supporting arms 141, 142, 143. The seabed penetrating anchors 141c, 142c, 143c are each configured to be embedded within the seabed when the tidal turbine 100 is in use. The seabed support structure is a gravity base. In particular, the block weights 141b, 142b, 143b are configured to anchor the tidal turbine 100 to the seabed.

The first supporting arm 141 and the second supporting arm 142 each have a mass which is greater than the third supporting arm 143. This is achieved by the weight blocks 141b, 142b each being of a greater mass than the weight block 143b.

The first supporting arm 141 and the second supporting arm 142 are each longer in length than the third supporting arm 143. Specifically, the respective seabed contact points between the supporting arms are configured such that the contact points of each of the first supporting arm 141 and the second supporting arm 142 are at a greater radial extent than the contact point of the third supporting arm 143.

Turning to Figure 2, the arrangement of the three supporting arms 141, 142, 143 around the central tower 130 is described.

The supporting arms 141, 142 are disposed about the central tower 130 such that the first supporting arm 141 and the second supporting arm 142 (i.e. the first pair of neighbouring supporting arms 141, 142) define a first angular spacing a.

The supporting arms 142, 143 are disposed about the central tower 130 such that the second supporting arm 142 and the third supporting arm 143 (i.e. the second pair of neighbouring supporting arms 142, 143) define a second angular spacing b.

The supporting arms 141, 143 are disposed about the central tower 130 such that the first supporting arm 141 and the third supporting arm 143 (i.e. the third pair of neighbouring supporting arms 141, 143) define a third angular spacing y.

In the tidal turbine 100 of Figures 1 to 3, the first angular spacing a is greater than each of the second angular spacing b and the third angular spacing g. In the tidal turbine 100 of Figures 1 to 3, the second angular spacing b and the third angular spacing g are approximately equal.

In other embodiments, any two of the first angular spacing a, the second angular spacing b and the third angular spacing g may be non-equal. In certain embodiments, all three of the first angular spacing a, the second angular spacing b and the third angular spacing g may be non-equal.

As can be seen in Figure 2, the angular spacings referred to are the angular spacings about the central tower 130.

The first angular spacing a may be between about 130 degrees to about 160 degrees. The second angular spacing b may be between about 100 degrees to about 115 degrees. The third angular spacing g may be between about 100 degrees to about 115 degrees. In all arrangements with exactly three supporting arms (such as that shown in Figures 1 to 3), the angular spacings between all neighbouring pairs totals 360 degrees.

As can be seen in Figure 2, the radially outermost end of the first supporting arm 141 and the radially outermost end of the second supporting arm 142 line on a notional line connecting the two. The notional line intersects the tidal blade rotation plane P at an angle of about 90 degrees.

Referring to Figure 2, the third supporting arm 143 extends along a direction which is generally parallel to the tidal blade rotation plane P.

As can be seen in Figure 2, the radially outermost end of the first supporting arm 141 and the radially outermost end of the second supporting arm 142 are each at a greater radial distance from the central tower 130 than the radially outermost end of the third supporting arm 143.

The radially outermost end of the first supporting arm 141 and the radially outermost end of the second supporting arm 142 extend approximately the same radial distance from the central tower 130. The radially outermost end of the second supporting arm 142 extends past the tidal blade rotation plane P when seen from above.

Figure 3 shows a side view of the tidal turbine 100. As can be seen, the bottom of the central tower 130 is above the bottoms of each of the supporting arms 141, 142, 143. Accordingly, when in use on a flat seabed, the tidal turbine 100 is configured such that the central tower 130 does not contact the seabed.

Each of the supporting arms 141, 142, 143 extend both radially outwardly from the central tower 130 and longitudinally downwardly from the central tower 130.

Although particular embodiments of the disclosure have been disclosed herein in detail, this has been done by way of example and for the purposes of illustration only. The aforementioned embodiments are not intended to be limiting with respect to the scope of the appended claims.

For example, even though the above embodiment refers to a tidal turbine 100 with exactly three supporting arms, the tidal turbine may be modified to include more supporting arms, such as exactly four, five or six supporting arms.

Furthermore, the above embodiment refers to a tidal turbine 100 with a gravity base. However, alternative ways of anchoring the tidal turbine 100 to the seabed are envisaged such as securing the supporting arms to the seabed with grout.

Moreover, even though the above tidal turbine 100 has seabed penetrating anchors 141c, 142c, 143c, these are purely optional. Instead, the tidal turbine 100 may be anchored to the seabed purely by the frictional forces caused by the weight of the gravity base (i.e. the block weights 141b, 142b, 143b). It is contemplated by the inventors that various substitutions, alterations, and modifications may be made to the invention without departing from the scope of the invention as defined by the appended claims.