GB2596270A

GB2596270A - Offshore tidal stream turbine system

Info

Publication number: GB2596270A
Application number: GB2006542.1A
Authority: GB
Inventors: Peter Mackinnon Calum
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-05-04
Filing date: 2020-05-04
Publication date: 2021-12-29
Also published as: GB202006542D0

Abstract

A tidal stream energy system comprising: a semi-submersible weathervaning floating structure 100 with tidal stream turbines and handling systems. The structure has a single point mooring system 103 and a separate dynamic electrical conduit 105. The tidal stream assembly (200, fig 2) floats on the surface. The hybrid mooring line (400 fig 2) is attached to an anchor foundation structure (500, fig 2). The hybrid mooring line and the dynamic electrical conduit allow the structure to weathervane so that the blades are always directed into the oncoming current flow.

Description

OFFSHORE TIDAL STREAM TURBINE SYSTEM

FIELD OF THE INVENTION

The present invention relates to a tidal stream energy floating system that weathervanes on a single point mooring arrangement. The invention may also relate to a hybrid mooring system and rotating connector which may be used in conjunction with a weathervaning floating system. Further to this, the invention may relate to hybrid subsea connection system.

BACKGROUND OF THE INVENTION

Tidal Stream Turbines are used to convert ocean current flow energy into electrical energy which goes on to be used for powering homes and commercial buildings. Tidal stream is being used more frequently as energy suppliers seek alternative ways to harvest the earth's natural resources. Tidal stream currents operate on a lunar cycle and the energy resource is entirely predictable. Currents can provide a reliable baseline energy source, in comparison to wind, wave, and solar energy which depend on the weather conditions. The dependability of tidal stream energy makes it an attractive opportunity for energy suppliers.

However, tidal stream energy comes with some significant challenges. Firstly, the turbine device generally has to work in a bi-directional current regime, it has to operate in both directions of flow. Secondly, the turbine device has to work in a harsh offshore environment. Thirdly, the capital costs and the costs of maintaining and repairing the equipment during the operating lifetime are high.

Tidal Stream devices can be mounted on the seabed, mid water or just below the surface. The optimal location for the device blades is mounted on a floating structure and operating just below the water surface as this is where the current is highest.

The main problem with locating the blades just below the sea surface is the cavitation effect. This can damage standard propeller type blades during operation, resulting in generating downtime.

Floating devices can operate in tidal streams that flow in one direction only or in bidirectional regimes that follow a lunar cycle and flow in opposite directions in turn.

Tidal stream devices can operate in inshore channels between land and islands or in the open ocean.

The floating devices have to operate in high tidal stream conditions. This requires the floating structure to have a low drag profile to minimise the mooring loads.

A robust mooring system has to be provided to counteract the structure tidal current loadings and also wave loadings.

In a bi-directional current regime, the mooring system has to enable the floating structure and blade system to generate energy from both directions of flow.

One way to do this is to have the floating structure moored in a fixed location and heading using a multi leg mooring system. In this configuration, the blades on the turbine device would have to be fully rotatable to enable them to face into the current flow from both directions.

The other way is to enable the floating structure to weathervane so that the blades are always directed into the oncoming current flow. This would require the use of a single point mooring system. The floating structure would rotate about the single point mooring.

The electrical power generated by the tidal stream device will require to be transmitted using a dynamic power cable from the floating device to the export power cable system located on the seabed.

For the floating system using a fixed multi leg mooring system, the dynamic cable would be attached to any point on the floating structure and connected directly to the tidal stream generating device.

For the weathervaning floating system on a single point mooring system, the dynamic cable would be attached at the mooring connection point. The issue with weathervaning floating vessels is the difficulty of transferring power whilst allowing the vessel to weathervane.

Some form of rotary electrical connection would be required to connect from the dynamic cable to the tidal stream generating device. The solution in the art is to use a slip ring, which uses a series of brushes to transmit power from one rotating body to another. However, slip rings are expensive, unreliable, and cannot cope with high power loads. A reliable rotary connection system is required for high voltage transmission systems.

A specialised subsea connection system will be required to connect the dynamic power cable to the seabed export cable as this will have to be operated in the high tidal current regime. The connection may be operated using diver intervention or by using Remotely Operated Vehicle (ROV) intervention.

Electrical power cables and connectors have proven to be unreliable in the offshore renewable energy business and have failed either during installation or during subsequent operations. A robust subsea cable and connector system is required. This is particularly relevant for the dynamic cable which is subject to the current and wave motions during operations.

The floating structure should be configured to ensure that personnel can safely and easily access the structure. Many of the current floating structures have a very low freeboard, which makes access difficult in high wave conditions. Personnel access will be required to maintain and repair the turbine in a range of weather conditions.

Another issue which may arise is if the heavy generator or any of the heavy components in the turbine system need replacing. In some systems, the generator is located in a subsea housing and the electrical switchgear is located in inaccessible compartments within the floating structure hull. Replacement of heavy equipment offshore may be a difficult operation which may require good weather in order to be performed.

It should be possible to change out the heavy components offshore to ensure that the system can continue generating. It should not be the case that the floating structure has to be returned to port or to a dry dock to effect repairs. This would be a very expensive operation and also result in an extended period where no electricity was being generated.

For the above reasons, there remains a need to address or mitigate at least one or more of the aforementioned problems. A large change in the design and method of operation of tidal stream turbine devices is required to make the industry economically viable.

It is therefore an object of the present invention to provide a new semi-submersible tidal stream floating device that weathervanes around a single point mooring system.

The structure will consist of a base member underwater, a mooring float at the bow and a number of tidal turbine support floats at the stern of the structure. The semi-submersible design is very stable in high wave conditions.

The floating structure will feature a plurality of tidal stream turbine units The turbines will comprise of a generator, drive system and loop propeller system The turbine arrangement will be configured to have an integrated handling system that enables the heavy generators and drive components to be changed out offshore.

The structure will be configured to provide personnel access at the aft of the structure.

Another object of the present invention is to provide a single leg mooring system that comprises of a conduit with internal electrical power cable, strength member and buoyancy elements. The mooring system will also comprise of an anchor foundation structure and a rotational connector system on the floating structure, to enable continuous power transmission whilst allowing the floating structure to rotate freely.

Another object of the present invention is to provide a staged connection system for the conduit with internal electrical power cable. The connection will have an integrated flushing system for inhibited protection fluids.

Another object of the present invention is to provide a fish farm integrated into the floating structure to improve the economics of the offshore installation.

Another object of the present invention is to mount a wind turbine onto the floating structure to improve the economics of the offshore installation.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provided a tidal stream turbine assembly comprising: a weathervaning floating structure, and a plurality of turbine units, each with its own handling system: wherein the floating structure may be a semi-submersible design to provide additional stability for offshore ocean applications: wherein the structure may be designed to weathervane around a bow mounted mooring system, the main floating structure would be located astern of the bow mooring system: wherein the tidal stream turbine units would be mounted at the stern of the structure.

The floating structure would weathervane around the bow mooring system to ensure that the tidal stream turbines mounted on the stern of the structure would always face into the current streams.

The structure will consist of a base member underwater, a mooring float at the bow and a plurality of tidal turbine support floats at the stern of the structure.

The floating structure would be designed to minimise the drag loadings from the tidal stream current and waves.

The structure may have a plurality of tidal stream turbine devices mounted on floating members at the stern of the structure.

The turbine rotatable blade assembly may be mounted horizontally, thereby forming a horizonal axis tidal stream turbine.

The blade assembly may comprise a plurality of blades, for example, there may be 3 or 6 blades. The blades may be a standard tidal stream propeller profile.

The blades may be looped propeller design. The looped propeller design is more efficient and is less susceptible to the cavitation effect. This will enable the propeller to be positioned closer to the surface, where the tidal stream flow is higher, thereby generating more power.

The blade assembly may be connected to a vertical drive shaft to transmit the rotary drive up to the structure deck level.

The vertical drive shaft may be connected directly to a vertically orientated electrical generator unit. Alternatively, the drive shaft may be connected, via a right-angled gearbox, to a horizontally mounted electrical generator unit, mounted on the main deck.

A handling system may be provided at each turbine location. This may be a crane, A Frame or gantry type handling system. The handling system may be a permanent feature on the structure or may be just be temporarily installed for the component change out operation.

The handling system may be used to transfer the generator unit, or any other heavy components from the structure main deck to the deck of a support vessel, and back again.

The handling system may be used to transfer the vertical drive system and blade assembly from the structure to the deck of a support vessel, and back again.

The vessel may have a supporting handling system to enable the loads to be quickly and safely be handled offshore. The turbine equipment can either be repaired on the vessel offshore, in port or transferred on land for repair.

The floating structure may be configured to have an integrated fish farm.

The floating structure may be configured to have an integrated horizontal axis wind turbine.

According to a second aspect of the present invention, there is provided a mooring system assembly comprising: a deck connection system, a hybrid mooring line and an anchor foundation structure: wherein the anchor foundation is secured to the seabed and incorporates an articulation mechanism for the base of the mooring line: wherein the base of the mooring line has a subsea connection interface: wherein the hybrid mooring line comprises of an electrical power transmission cable housed within a protection conduit and supported by tension members and buoyancy elements: wherein the conduit is filled with inhibitor protection fluids: wherein the top of the hybrid mooring line comprises a termination head that interfaces with the deck connection system: wherein the connection system has an integrated rotational bearing to enable the floating structure to weathervane around the hybrid mooring line: wherein the connection system comprises of an integrated motion damping system: wherein the connection is configured to enable the electrical power transmission cable to freely rotate within the protection conduit.

The anchor foundation structure may be a gravity structure, suction pile structure, driven pile structure or any design of structure to suit the seabed conditions.

The anchor structure will have an integrated articulation mechanism, this may be a mechanical universal joint, flexible joint or a chain based system.

The articulation mechanism will have an anchor member and docking interface for the base of the hybrid mooring line.

The base of the hybrid mooring line will have a docking interface and locking mechanism that can connect with the articulation mechanism.

The base of the hybrid mooring line will have a connection interface for the electrical power transmission cable.

The electrical transmission cable will be housed inside the mooring conduit for protection.

The conduit will be filled with inhibitor protection fluid, this will prevent corrosion and degradation of the cable.

The hybrid mooring line will also have a plurality of integrated tension members which may be chain, wire rope or fibre rope The mooring loads will be shared by the tension members. The conduit may also share the tension loads.

The hybrid mooring line will have a number of buoyancy elements to support the catenary during operation.

When not connected to the floating structure, the mooring line will float mid water, supported by the buoyancy elements.

The top of the hybrid mooring line will have a termination head which will be clamped to a pull-in cap.

The deck connection interface will comprise of a structural inlet guide funnel, hang off mechanism and winch frame.

The deck connection interface may be positioned on the floating structure at the natural catenary angle of the mooring line when under load.

A pull in wire winch and sheave arrangement will be mounted on the winch frame. The wire will be routed from the winch, via the sheaves down through the centre of the hang off mechanism and guide funnel.

During operation, the winch wire will be attached to the termination head pull in cap. The termination head will be pulled up into the guide funnel into the hang off position.

Locking plates on the hang off mechanism will then be actuated to lock the termination head to the hang off mechanism.

A rotating bearing arrangement will be provided below the locking plates. This will enable the deck connection interface on the floating structure to rotate around the hybrid mooring line. The hybrid mooring line will remain on a fixed heading and will not rotate.

The hang off mechanism has an integrated load damping system. This will enable the termination head to move axially, depending on the mooring loads. This may be a passive or active system or a combination of both.

The termination head can be fitted with a tensioning and load measurement system on each of the tension members. This will enable the load in each tension member to be shared evenly.

When the termination head is locked in the hang off mechanism, the pull in cap can be removed.

The electrical power transmission cable can then be pulled out of the top of the conduit and connected into a junction box on the winch frame.

The junction box will be connected by deck cable to each of the tidal stream turbines.

During operation, as the floating vessel weathervanes and rotates about the mooring line then the electrical cable will twist along its length, within the conduit. The cable may be able to twist 100 times in each direction without any damage occurring.

In the event that the cable may twist more than 100 turns then, it would have to be disconnected from the junction bow, untwisted, and then reconnected back into the junction box.

As the electrical cable is able to twist within the conduit then this provides the same functionality as a rotatable electrical connector and replaces the requirement to have slip rings.

According to a third aspect of the present invention, there is provided a subsea connection system comprising: an inboard connection clamp hub, an outboard termination head and a pull in system; wherein the inboard connection clamp hub comprises of a pull-in bracket, a connection flange, an internal electrical connector, a connection clamp, a protection cap and a fluid injection system: wherein the outboard termination head compromises of a connection flange, an internal electrical connector and a protection cap: wherein the pull in system comprises of a winch system, articulation frame, cap removal system, electrical connector tool, clamp closing tool and fluid injection system.

The inboard connection clamp hub would normally be mounted on the static structure, such as the hybrid mooring line or a subsea distribution manifold The outboard termination head would normally be mounted on the subsea cable. This could be the dynamic cable connecting a subsea manifold to the bottom of the hybrid mooring line. Alternatively, this could be the subsea export cable or a subsea jumper cable.

The inboard connection clamp hub and the outboard termination head comprises of an electrical insert housed and protected within a mechanical conduit body.

The electrical insert could also have a number of hydraulic lines, control wires, fibre optic lines integrated into the connector.

During the pull-in operation, the pull in system would be mounted on the pull-in bracket on the inboard connection clamp hub.

The pull in wire or rope would then be deployed and connected to the outboard termination head.

The winch would then pull the outboard termination head to the inboard connection clamp.

The articulation frame would then be used to axially align the inboard flange and the outboard flange.

The cap removal tool would then be used to remove the protection cap from the inboard and outboard flanges The electrical connection tool would then be used to move the electrical inserts together to form the electrical power transmission connection.

The outboard flange would then be moved axially to engage with the inboard flange.

The clamp closing tool would then be used to close the clamp and connect the inboard and outboard flanges together in a sealed connection.

The fluid injection system would then be used to flush the void inside the connection to remove the seawater and replace it with inhibited protection fluid.

The pull in system would then be removed from the pull in bracket.

The connection operation could be performed using diver intervention or by using Remotely Operated Vehicle intervention.

During the pull in and connection operation and subsequent operations, the loads would be accommodated by the inboard connection clamp hub and the outboard termination head, the electrical inserts would not be subjected to any load.

An off-shore energy generation system, wherein the tidal stream energy device according to the first aspect of the present invention is connected to the mooring system according to the second aspect of the present invention which is connected to the subsea connection system according to the third aspect of the invention.

The mooring system and subsea connection system should not be limited to tidal stream energy devices, but may be used on other undisclosed systems, such as floating wind energy, floating wave energy, floating solar energy.

The tidal stream floating structure, mooring system and subsea connection system may be used in combination with other undisclosed systems, such as floating wind energy, floating wave energy, floating solar energy.

Any of the previously described inventions may also be coupled with a fish farm.

Further optional features disclosed in relation to each aspect of the invention correspond to further optional features of each other aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting example embodiments the present invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a weathervaning floating structure on a single point mooring system, in accordance with the prior art, showing the multiple mooring lines and the separate dynamic electrical conduit; Figure 2 shows an embodiment of the present invention, depicting the tidal stream assembly weathervaning on a hybrid mooring line and anchor foundation structure; Figure 3 is similar to Figure 2, showing more details of the components on the seabed for clarity.

Figure 4 shows a detailed view of the hybrid mooring line, anchor foundation structure and the electrical jumper assembly.

Figure 5 shows an embodiment of the present invention, depicting the hybrid mooring line and the deck interface assembly. A section of the hull on the tidal stream assembly has been removed for clarity.

Figure 6 shows an isometric view of the hybrid mooring line, the deck interface assembly and the tidal stream assembly with a section of the hull removed for clarity.

Figure 7 shows an isometric view of the deck interface assembly shown in a vertical orientation on a section of vessel deck Figure 8 shows a view of the termination head positioned below the vessel hull.

Figure 9 shows the termination head located in the hang off position above the rotary support bearing.

Figure 10 shows a view of the locking ring installed between the termination head and the rotary support bearing.

Figure 11 shows a view of the electrical power cable pulled out of the protection conduit on the termination head and connected to the junction box.

Figure 12 shows a view of the motion damping system in the fully extended and in the fully retracted positions.

Figure 13 shows a view of the engagement of the hybrid mooring line into the anchor foundation connection interface.

Figure 14 shows the electrical jumper assembly being pulled into the inboard connection clamp hub on the hybrid mooring line.

Figure 15 shows a view of the outboard termination hub pulled into a position adjacent to the connection clamp hub.

Figure 16 shows a view of the alignment system being deployed from the pull in system to align the outboard termination hub with the inboard connection clamp.

Figure 17 shows a view of the electrical inserts in the connected position.

Figure 18 shows the outboard termination hub in the final position on the inboard connection clamp hub.

Figure 19 shows an embodiment of the present invention, depicting the tidal stream floating assembly, weathervaning into the current, around the hybrid mooring line.

Figure 20 shows an isometric view of the tidal stream floating assembly with two out of the four tidal turbine assemblies mounted onto the stern of the floating structure.

Figure 21 shows a side elevation of the handling system articulated into the horizontal position and supporting the tidal turbine assembly.

Figure 22 shows a side elevation of a support vessel with a handling system articulated into the horizontal position Figure 23 shows an isomeric view of the support vessel with the handling system supporting the tidal turbine.

Figure 24 shows an isomeric view of the tidal stream floating structure with an integrated fish farm and wind turbine

DETAILED DESCRIPTION

A description of the figures is given below.

Figure 1 shows the sea surface 101, seabed 102 and a weathervaning floating structure on a single point mooring system 103, in accordance with the prior art, showing the multiple mooring lines 104 and the separate dynamic electrical conduit 105.

The floating structure 100 is free to rotate about the single point mooring system 103.

The dynamic electrical conduit 105 on the seabed may be connected to the national grid network via subsea cables.

Figure 2 shows an embodiment of the present invention, showing the sea surface 101 and the sea bed 102. The tidal stream assembly 200 can be seen floating on the sea surface 101, whilst the hybrid mooring line 400 can be seen to be attached to the anchor foundation structure 500 on the seabed 102. The bottom of the hybrid mooring line 400 is connected via an electrical jumper assembly 600 to a subsea electrical manifold structure 700. The subsea electrical manifold 700 on the seabed may be connected to the national grid network via a subsea export cable 800.

The semi-submersible floating structure 200 is free to rotate about the hybrid mooring line 400.

The water depths which the tidal stream assembly 200 is operable in, may vary from 25 to 1500 metres deep.

Figure 3 is similar to Figure 2, showing more details of the components on the seabed for clarity.

Figure 4 shows a detailed view of the hybrid mooring line 400, anchor foundation structure 500 and the electrical jumper assembly 600.

The anchor foundation structure 500 is installed on the seabed 102. The anchor member 502 is connected to the articulation mechanism 501. The anchor member 502 has a connection interface 503 that docks to the base of the hybrid mooring line base member 401.

During the installation operation, the hybrid mooring line 400 would be lowered down to the anchor foundation structure 500. The hybrid mooring line base member 401 would then be inserted into the connection interface 503 and clamped into position.

The hybrid mooring line 400 comprises of an electrical power cable 403 housed within a protection conduit 404. The protection conduit 404 is supported by a plurality of tension members 405. The hybrid mooring line 400 is supported in the water column by buoyancy elements 406 The hybrid mooring line base member 401 is fitted with an inboard connection clamp hub 402.

The electrical jumper assembly 600 comprises of an electrical power cable 601 housed in a protective conduit 602. The assembly catenary is supported by a number of buoyancy elements 603.

The electrical jumper assembly 600 is terminated in an outboard termination head 604. The outboard termination hub 604 is connected to the inboard connection clamp hub 402.

Figure 5 shows a detailed view of the hybrid mooring line 400 and the deck interface assembly 300. A section of the hull on the tidal stream assembly 200 has been removed for clarity.

The top section of the hybrid mooring line 400 is shown, comprises of an electrical power cable 403 housed within a protection conduit 404. The protection conduit 404 is supported by a plurality of tension members 405. The hybrid mooring line 400 is supported in the water column by buoyancy elements 406.

Figure 6 shows an isometric view of the hybrid mooring line 400, the deck interface assembly 300 and the tidal stream assembly 200 with a section of the hull removed for clarity.

Figure 7 shows an isometric view of the deck interface assembly 300 shown in a vertical orientation on a section of vessel deck 304. The main interface to the vessel deck 304 is the guide funnel 305 onto which is mounted the winch frame 306.

The winch 301 and diverter sheave system 302 is mounted on the winch frame 306. The pull-in wire 313 is routed from the winch 301 over the diverter sheaves 302.

The mooring termination head 303 is located at the top of the hybrid mooring line 400 During operation, the termination head 303 will be located in the deck interface assembly 300 supported by a locking ring 311, rotary support bearing 310 and guide tube 309.

The guide tube 309 is mounted on a motion damping system 307.

A load measurement and tensioning system 312 is provided on the tension members 405 on the termination head 303.

The electrical power cable 403 is housed within the protection conduit 404 on the termination head 303. During operation, the electrical power cable is connected into the junction box 308.

During operation, the termination head 303 does not rotate as it is part of the hybrid mooring line 400 and is supported by the rotary support bearing 310.

All of the other components in the deck interface assembly 300 are attached to the floating structure, which is free to rotate about the hybrid mooring line 400.

The electrical power cable 403 is free to rotate within the protection conduit 404, as the deck interface assembly 300 rotates about it.

Figure 8 shows a view of the termination head 303 positioned below the guide funnel 305. The pull-in wire 313 is routed from the winch 301 over the diverter sheaves 302 and down through the guide funnel 305 to the termination head 303.

During the pull in operation, the termination head 303 is pulled through the vessel hull 304, centralised using the guide funnel 305 and then hung off within the deck interface assembly 300.

Figure 9 shows the termination head 303 located in the hang off position above the rotary support bearing 310.

Figure 10 shows a view of the locking ring 311 installed between the termination head 303 and the rotary support bearing 310.

The load measurement and tensioning systems 312 are installed between the tension members 405 and the locking ring 311.

Once the locking ring 311 is installed then the pull in cap 314 and wire 313 can be 15 removed.

Figure 11 shows a view of the electrical power cable 403 pulled out of the protection conduit 404 on the termination head 303 and connected to the junction box 308.

Figure 12 shows a view of the motion damping system 307 and the guide tube 309.

The view on the left shows the motion damping system in the fully extended position.

The view on the right shows the motion damping system in the fully retracted position.

Figure 13 shows a view of the engagement of the hybrid mooring line 400 into the anchor foundation connection interface 503.

The hybrid mooring line base member 401 would be positioned axially in line with the connection interface 503. The base member would then be inserted into the connection interface and locked in position.

In the event of failure of any of the components then the hybrid mooring line 400 could be removed using the reverse of the procedure.

Figure 14 shows a view of the electrical jumper assembly 600 being pulled into the inboard connection clamp hub 402 on the hybrid mooring line 400.

The pull in system 605 is mounted on the connector clamp hub 402 The pull in wire 606 is connected to the outboard termination hub 604 on the electrical jumper assembly 600.

The outboard termination hub 604 and the connection clamp hub 402 would be fitted with protection caps 607.

During operation, the winch would pull the outboard termination hub 604 from the seabed up towards the connection clamp hub 402.

Figure 15 shows a view of the outboard termination hub 604 pulled into a position adjacent to the connection clamp hub 402 The protection caps 607 are shown in position.

Figure 16 shows a view of the alignment system 608 being deployed from the pull in system 605 to align the outboard termination hub 604 with the inboard connection clamp hub 402. When this is completed then the protection caps 607 can be removed by the pull in system 605.

Figure 17 shows a view of the electrical inserts 609 in the connected position. This operation would be performed by the electrical connector tool in the pull in system 605.

Figure 18 shows the outboard termination hub 604 moved into the final position on the inboard connection clamp hub 402 by the articulation frame. The clamp would then be closed. The void area between the connection clamp hub 402 and the termination hub 604 would then be flushed with inhibitor protection fluid.

Figure 19 shows a side elevation of the tidal stream floating assembly 200, weathervaning into the current, around the hybrid mooring line 400. The handling system 201 and the tidal turbine assembly 202 are shown at the stern of the tidal stream floating assembly 200. A plurality of handling systems 201 and tidal turbine assemblies could be mounted on the tidal stream floating assembly 200.

Figure 20 shows an isometric view of the tidal stream floating assembly 200. The tidal stream floating structure 200 is shown with a fish farm 212, integrated into the submersible hull structure.

Two out of the four tidal turbine assemblies 202 are shown, as an example, mounted onto the stern of the floating structure.

The tidal turbine assembly 202 comprises of the blade and hub assembly 204, the vertical drive shaft arrangement 203 and the right-angled gearbox 205. The right-angled gearbox 205 would be connected to the deck mounted generator unit 206.

Alternatively, the generator 206 could be mounted axially on the top of the gearbox 205. The blade and hub assembly 204 could be configured with standard blades or could be configured with loop propeller blades.

The tidal stream floating assembly 200 is fitted with a tower base structure 207. This could be used as the mounting point for a wind turbine.

A machinery room area 208 is provided at the stern of the tidal stream floating assembly 200. This could be used to house generator units, electrical switchgear etc. Personnel would be able to access the tidal stream floating assembly 200 at the stern, in the lee of the wave motion and tidal currents.

A plurality of handling systems 201 would be mounted on the stern of the tidal stream floating assembly 200 to handle the generators 206 and any other heavy equipment.

Figure 21 shows a side elevation of the handling system 201 articulated into the horizontal position and supporting the tidal turbine assembly 202, detached from the tidal stream floating structure 200.

Figure 22 shows a side elevation of a support vessel 209 with a handling system 210 articulated into the horizontal position. The handling system 210 is also connected to the tidal turbine assembly 202. The load is then transferred from the handling system 201 to the handling system 210.

Figure 23 shows an isomeric view of the support vessel 209 with the handling system 210 supporting the tidal turbine 202. The handling system 210 would be used to handle the tidal turbine assembly 202 from the water to a position on deck. A tidal turbine assembly 202 is shown positioned on the deck of the support vessel 209 as an example.

Figure 24 shows an isomeric view of a horizontal axis wind turbine 211 mounted on the tidal stream floating structure 200.

In this system configuration, electrical energy can be produced from both the horizontal axis wind turbine 211 and the tidal stream turbine assemblies 202.

The tidal stream floating structure 200 is shown with a fish farm 212, integrated into the semi-submersible hull structure.

Whilst specific embodiments of the present invention have been described above, it will be appreciated that departures from the described embodiments may still fall within the scope of the present invention.

Claims

CLAIMSA tidal stream assembly comprising: a semi-submersible weathervaning floating structure and a plurality of tidal stream turbine assemblies and handling systems.
2. A tidal stream assembly according to claim 1, wherein the structure can be a semi-submersible offshore assembly design.
3. A tidal stream assembly according to claim 1, wherein the assembly is free to weathervane on a single point mooring so that the tidal stream turbines are always facing the oncoming current stream.
A tidal stream assembly according to any preceding claim, wherein a plurality of tidal stream turbines and handling systems are mounted on the stern of the unit.
5. A tidal stream assembly according to any preceding claim, wherein the tidal turbine generator and drive system / blade hub can be removed from the generator using the handling system.
6. A tidal stream assembly according to any preceding claim, wherein the assembly further comprises a horizontal axis wind turbine mounted on the floating structure.An assembly according to any preceding claim, wherein the assembly further comprises a fish farm integrated into the floating structure.A mooring system assembly comprising: a hybrid single mooring line, the mooring line comprising connecting means for connecting to the floating structure; and connecting means for connecting to the seabed anchor foundation structure; wherein the mooring line is anchored to the seabed anchor foundation structure in a fixed orientation relative to the seabed wherein the mooring line comprises a protection conduit, an electrical power cable, and a plurality of tension strength members and buoyancy elements; wherein the floating structure is suited to freely rotate about the hybrid single mooring line, and wherein the floating structure comprises a motion damping system which maintains tension in the mooring line; A mooring system according to claim 8, wherein the connecting means between the anchor foundation and the mooring line is a universal joint or flexible joint arrangement 10. A hybrid mooring line according to claim 8, wherein the electrical power cable is located inside the protection conduit.11. A hybrid mooring line according to claims 8 and 9, wherein the plurality of tension strength members are located outside the protection conduit.12. A hybrid mooring line according to claims 8, 9 and 11, wherein the plurality of buoyancy elements are located along the length of the mooring line.13. A mooring system according to claim 8, wherein the mooring line is supported on the floating structure by locking plates mounted on a rotational bearing arrangement.14. A mooring system according to claim 8 and 13, wherein a motion damping system is provided between the rotational bearing arrangement and the floating structure.A mooring system according to claims 8, 13 and 14, wherein the electrical power cable is connected to a junction box on the floating structure.16. A mooring system according to claim 8, 13, 14 and 15, wherein the electrical power cable, motion damping system and the floating structure are free to rotate around the hybrid single mooring line.17. A mooring system according to claim 8 wherein the floating structure comprises hoisting means, to hoist the mooring line into the floating structure.18. A subsea connection system assembly comprising: an inboard mechanical/ electrical connector, an outboard mechanical/electrical connector, a pull-in and connection system and a fluid flushing system; wherein the inboard mechanical/electrical connector line is located on the base of the hybrid single line mooring; wherein the outboard mechanical/electrical connector line is located on the subsea dynamic jumper; wherein the pull in system can be mounted on the inboard mechanical/electrical connector; wherein the fluid injection system can be mounted on the inboard mechanical/electrical connector; 19. A connection system according to claim 18, wherein the electrical connector is mounted within the mechanical connector and is fully protected from the subsea environment and the installation and operational loads.20. A connection system according to claim 18 and 19, wherein the pull in system is used to move the outboard connector towards the inboard connector and fully close the electrical connector and then the mechanical connector in sequence.21. A connection system according to claim 18, wherein the fluid injection system is used to flush inhibiting protection fluid onto the fully connected assembly.22. A connection system according to claim 18, wherein the connection system can be used on any subsea connection application such as dynamic cables on risers, seabed export and infield cables, subsea electrical distribution manifold hubs.23. An off-shore energy generation system wherein the tidal stream assembly according to any of claims 1 to 7 is connected to the mooring system according to any of claims 8 to 17.24. An off-shore energy generation system wherein the mooring system assembly according to any of claims 8 to 17 is connected to the subsea connection system according to any of claims 18 to 22.25. An off-shore energy generation system wherein the mooring system assembly according to any of claims 8 to 17 and the subsea connection system according to any of claims 18 to 22 are used for either tidal stream energy, floating wind energy, wave energy and solar energy or some combination thereof.