GB2546252A

GB2546252A - Floating wind turbine

Info

Publication number: GB2546252A
Application number: GB1600224.8A
Authority: GB
Inventors: Benoni Hindmarch Martin; Torsvik Jone
Original assignee: Statoil Petroleum ASA
Current assignee: Equinor Energy AS
Priority date: 2016-01-06
Filing date: 2016-01-06
Publication date: 2017-07-19
Also published as: GB201600224D0

Abstract

A method of providing electrical energy to a power consumer and an offshore wind turbine 1, comprising a generator 26 for generating electrical energy for the power consumer 2 from wind energy, and an energy storage device 18 for providing electrical energy for the power consumer 20. The wind turbine may be a floating wind turbine or a spar buoy and may be further arranged to provide a minimum amount of electrical power for at least a predetermined time and may also comprise a frequency converter 28 connecting the generator to the energy storage device, either on the lower voltage side of a transformer 30, or the higher voltage side. The energy storage device may be housed within a support structure 2, may incorporate part of the balance weight 7 of the floating turbine. The generator and energy storage device may each include a controller which may be integrated. The wind turbine may have a second generator of one of solar photovoltaic cells 24 and/or fuel heat 16 or pressure driven generators. The energy storage may be a battery 18.

Description

FLOATING WIND TURBINE

The invention relates to floating wind turbine for providing electrical energy to a power consumer.

When an offshore power demand site is far offshore, the power supply from the conventional onshore power-generation units can become expensive. Accordingly, there is a desire to be able to generate electrical energy offshore:

For a large electrical power consumer with long-term power requirements, such as on offshore oil and gas platform or a large oil and gas production vessel^ it is known to use gas turbines combined with diesel generation units on the platform or vessel to generate the electricity fir the stPnd-alone electrical grid when fuel gas and diesel are available.

For a small electrical power consumer for a short-term, such as for powering an offshore measurement instrument for one year, it is known to provide offshore wind turbines which provide the required electrical energy.

However, the current Offshore renewable energy-based power systems are nolalways satisfactory due to the inherent variability in power production caused by e,g, variable wind conditions in the case of a Wind turbine.

According to a first aspect, the present invention provides a floating wind turbine for providing electrical energy to a power consumer, the floating wind turbine comprising: a generator (i.e. a wind turbine generator) for generating electrical energy for the power consumer from wind energy, and an energy storage device for providing electrical energy for the power consumer.

Due to the fact that the offshore wind turbine may be arranged to provide electrical energy from an energy storage device to the consumer, the wind turbine may be able to reliably provide electrical energy to a power consumer, even if there is no wind or the wind speed is low.

The floating wind turbine may be arranged to provide a continuous electrical energy output (e.g. a guaranteed continuous electrical energy output for a period of time, such as one week). For example when there is temporarily low wind speed or no wind, electrical energy can he provided to consumer from the energy storage device.

The floating wind turbine may be arranged to provide a minimum amount of electrical power for a power consumer for a predetermined period of time; e.g. at least one day, or one week, or one month. the energy storage device may be for storing energy generated by the wind turbine generator.

The energy storage device may be for at least temporarily, storing energy generated by the wind turbine generator before providing the energy to the oonsumen eg, the energy storage device is not for conditioning the power supply and/or powering internal components of the wind turbine itself.

The energy storage device may be fully integrated in the floati ng wind turbine.

The floating wind turbine may also comprise equipment for generating electrical energy from a second energy source (i.e. an energy source which is different to wind).

The floating wind turbine may also comprise a fuel generator and/or a solar system (re, a system which generates electrical energy from solar energy) for providing electrical energy to the consumer.

The invention may be regarded as being directed to an offshore wind turbine which comprises the energy storage device for providing electrical energy to the consumer and not tb an offshore device which comprises both a wind turbine and the energy storage device.

It was realised that the floating wind turbine may be used to house or mount: the energy storage device.

Thus the invention may utilize the floating wind turbine structure to accommodate an energy storage device. The energy storage device may be housed by, mounted on, or within the floating wind turbine structure itself (i.e. the support structure!

The energy storage device for providing the electrical energy to the consumer may le mounted on the wind turbine.

The energy storage device for providing the electrical energy to the consumer may be housed within the wind turbine. Per example, the energy storage device may be physically fitted on the inside of the floating wind turbine.

The substructure of the floating wind turbine may be large. For example, for a 6 MW floating wind turbine the substructure may have a diameter of around If meters and length of 100 meter. Thus, the energy storage device may be housed within the substructure of the wind turbine.

When the wind turbine comprises a balance Weight, the energy storage device may provide at least part of the balance weight of the floating wind turbine. file energy storage device may be integrated with, and Optionally replace part of, a balance weight system of the floating wind turbine. This may be in the support structure of the floating wind turbine.

This balance weight may be used to help keep the wind turbine upright.

The floating wind turbine may be specially designed so that the energy Stooge device can be part of the balance weight. in fact, it was realised that a floating wind turbine may be used to house or mount equipment which is used to provide a reliable source of electrical energy to a power consumer.

The energy storage device may comprise one or more batteries or a battery pack.

The wind turbine may comprise a frequency converter and/or a wind turbine generator transformer. The wind turbine generator may provide power to a consumer and/or the equipment via the frequency converter and/df the wind turbine generator transformer.

When the wind turbine comprises a frequency converter and an energy storage system, the energy storage system may be electrically connected to the wind turbine generator in the frequency converter. For example, the energy storage system may be directly electrically connected to the frequency converter which is electrically connected to the wind: turbine generator.

When the wind turbine comprises a wind turbine generator transformer and an energy storage system, the energy storage system may be electrically connected to the wind turbine generator on the lower voltage Side |e.g. a low voltage side) of the transformer or on the higher voltage side (e.g. a medium voltage side) of the transformer. When the energy storage system is electrically connected to the wind turbine generator on the lower voltage side (e g. a low voltage side) of the transformer, the energy storage system may be connected between the wind turbine generator and the wind turbine generator transformer.

This connection may be between the frequency converter arid the wind turbine generator transformer:.

When the energy storese system is electrically connected to the wind turbine generator on thf higher voltage side (e.g. a medium voltage side) of the transformer, the connection may he between the wind turbine transformer and the consumer.

The---flc>alihp :wjrtd:::turt>ine: may be arranged to provide electrical energy from the energy storage device simultaneously or subsequently to providing electrical energy from the wind turbine generator.

The floating wind turbine may be arranged to provide electrical energy from the energy storage device simultaneousiy or subsequently to, generating electrical energy from the wind energy.

The energy storage device may provide electrical energy which supplements the electrical energy generated from wind. The energy storage device may be relied on when the wind speeds are low or zero. The energy storage device may be used to generate supplementary electrical energy when the wind turbine is operating below its rated wind speed.

The energy storage device may be used for a peidd of time when the wind energy cannot be used alone to generate sufficient electrical energy for the needs of the power consumer.

The energy storage device may be used to generate Supplementary electrical energy when the power consumption of the consumer is greater than the amount of power which can be supplied from the wind energy alone.

The offshore wind turbine may be arranged to generate electrical energy from wind energy and/or another energy source such as fuel or solar energy, and store the energy in the energy storage device.

This means that even if sufficient electrical energy for the needs of the consumer cannot be generated at a particular time from other energy sources the offshore wind turbine can Still be used 1b provide additional energy to the consumer.

The offshore wind turbine may only generate electrical energy from the energy storage device when no electrical energy is being generated from wind energy.

The offshore wind turbine may comprise one or more second generators for generating electrical energy from a second energy source.

The second generatorisj mayr for example, comprise one Or more solar photovoltaic ceils and/or one or mere fuel (e.g. diesel^ heat or pressure driven generators; The second generator may comprise an engine, such as an internal combustion engine, heat engine or thermal expansion engine driven by burning fuel, heat or a thermal energy potential, and an electrical generator which is driven by the engine. The engine may be a reciprocating engine or a turbine engine.

The second generator may be a fuel cell.

The offshore wind turbine may be arranged to generate electrical energy from a plurality of different secondary energy sources. The secondary energy sources may comprise both renewable energy sources and non-renewable energy sources.

The Offshore wind turbine may for example comprise a solar system, such as a photovoltaic cell, and/or a diesel generator in addition to the energy storage system. This can allow the offshore wind turbine to reliably provide power with minimal impact from the environmental conditions.

The offshore wind turbine may comprise a suppo# structure. The support structure may comprise a tower, transition piece and/or foundation. For example, the tower may be supported by the foundation.

The wind turbine generator may be mounted towards the top of the fibbing structure.

The floating wind turbine may comprise a nacelle. The nacelle may be provided on the support structure, such as on the tower. The nacelle may house the wind turbine generator. The nacelle may also house the electronics associated with the generator. This generator may be the generator which is suitable for generating electrical energy from wind energy for the power consumer.

The gene-aldr (and optionally its associated electronics! may be located in the support structure, such as in the foundationpfthe support structure.

The offshore wind turbine may comprise a rotor. The wind turbine may comprise only one rotor. For example, the floating wind turbine may comprise of a support structure which supports a single rotor which is turned by the wind.

The rotor may be connected to the generator such that when the rotor rotates, the generator can produce electrical energy. The rotor may comprise a plurality of blades, such as three blades. The rotor blades may for example be 40 to 100 metres long, such as about II meters long.

The rotor may be provided on the support structure, such as on the tower. The rotor may comprise a Shaft. The shaft may be connected to the generator for generating electrical energy for the power consumer from wind energy. The generator may be connected to the rotor by any known means such as a reduction gearbox (this may be referred to as a “step-up" gearbox in terms of the direction of energy transfer), by direct connection to the electrical: generator or hydraulic transmission etc.

The support structure may he long (in comparison to the width). At least a portion of the support structure, such as the tower, may be approximately cylindrical in cross section.

The tower may be located above the water line in use.

The floating wind turbine may comprise a buoyant body. The buoyant body may form part of the foundation on which the tower is located or supported. In other words, the foundation may comprise a large buoyant body. This may be a large buoyant body.

The buoyant body may be a platform or raft-like structure- Alternatively, the buoyant body may be a "spar buoy" type structure. Such a structure may provide an elongate buoyant foundation.

The spar buoy may have a length which is significantly longer than its width, The spar buoy may be arranged to, in use, float in an upright position, i.e. with the length being vertical or near vertical relative to the plane of the body of water.

The foundation and tower may be a unitary structure. A transition piece may be located between the foundation and the tower, i.e. the transition piece may be part of the unitary structure.

Alternatively, the offshore wind turbine may comprise a foundation with a tower mounted thereon.

The floating wind turbine may be arranged so that it can be used in a water depth of about 100 meters to about 700 meters.

The support structure of the offshore wind turbine may have a diameter (for example at its widest point) of about 1 to 30rn, 10 to 20 m, such a§ about 15m.

The support structure may be up to 300m ih height, such as about 50 to 250m, 100 to 200m high or about 175m.

In the case of the spar buoy type floating: structure the operation draft (i.e. the draft of the support structure below the water line) may oe about 50 to 150m or about 100m.

The size of the wind turbine may depend on the consumer and what is supplied from the wind turbine to the consumer.

The wind turbine may comprise a balance weight. The balance weight may also be referred to as the ballast. This may be a large balance Weight (fir example, a 6 MW wind turbine may have a balance weight of more than 8000 tons). The balance weight may be used to help keep the Wind turbine upright and reduce the movement, i.e. in a position in which the wind turbine can operate to generate electrical energy from wind energy, and/or reduce movement of the wind turbine.

The balance weight may comprise one or more of permanent ballast, fixed ballast, water ballast, the energy storage device and other equipment for providing electrical energy to the consumer. For example, the equipment may be components which ire used to generate electrical energy from a second energy source, such as, secondary generators, the associated electronics, and/or fuel tanks.

The equipment, such as components which are used to generate eieefioai energy from a second energy source, may be used as ballast, i.e. as balance weight, in the Ohihore floating wind turbine.

The energy storage device, or other equipment, for providing electrical energy to the consumer may be located within {eg. housed within) the support structure, such as tower, transition piece or foundation, of the Wind turbine.

In the case of the spar buoy type floating structure, the energy storage device equipment for providing electrical energy to the consumer may be housed Within the operation draft.

The energy storage device may be attached to the outside of the wind turbine

The energy storage device may be housed within a container and/or a purpose buiit containment structure. Such a container or containment Structure may be attached to the wind turbine such as being mounted on the support structure of the wind turbine.

In this case, the energy storage device may be connected to the wind turbine by ductwork. The ductwork may supply dried or ciimatised air to protect the energy storage device from the marine atmosphere.

The energy storage device may be housed in a location which is subsea.

When the offshore wind turbine comprises two or more generators, one generator may be located on the support structure fsuch as at the top of the tower) and the other(s) may be located in the support structure of the wind turbine, such as in the foundation and/or below the water level.

In this case, the generator on the support structure may be the wind turbine generator for generating electrical energy from wind energy and the generator in the support structure may be a generator for generating electrical energy from the second energy source.

The offshore wind turbine may be tethered to the sea bed via one Or more mooring lines which may be provided with anchors, or attached to the sea bed with one or more articulated (hinged) lege, for example, in order to hold them at their desired installation sites.

When the floating wind turbine ie anchored by means of mooring lines, the arrangement may comprise three mooring lines. Each mooring line may comprise chain and/or spiral strand wire elements, f he offshore Wind turbine may comprise a controller. The controller may be arranged to control the offshore wind turbine.

The controller may control the provision of electrical energy generated by the wind turbine generator and/or from the energy storage device to the power consumer.

For example, the power output of the offshore wind turbine may be monitored, and if the power output is lower than a certain level (e.g. a desired or required level), the controller may cause the offshore wind turbine to provide additional electrical energy from the energy storage device to the consumer.

The controller may control the charging of the energy storing device.

Individual control systems may be provided for the wind turbine generator, the energy storage device and/or the consumer. These control systems may be connected and/or integrated so that they can be used to optimise the provision of electrical energy from the energy storage device and/or energy generated from wind from the wind turbine to the consumer.

The controller may receive inplit of the power required by the consumer and control the wind turbine, e.g. by controlling: the wind turbine to provide electrical energy from the energy storage device to the consumer, if the required power is greater than that which can be supplied from the wind source alone.

The offshore wind turbine may comprise a large standard commercial wind turbine.

The wind turbine may be combined with other types of power generation units.

The energy storage device may Comppe one or more electrical batteries. This may be referred to as a battery pack,

As used herein, the term 'floating wind turbine" means a wind turbine structure of the kind that is designed to float in a body of water, such as the sea, when in use.

The consumer may he located onshore or offshore, i.e. it may be an onshore consumer or it may be an offshore consumer. The consumer may 0% or be located on, a platform or a ship.

The consumer may be located op an island.

The consumer may be a large electrical power consumer (such as a power consumer which consumes of the order often or one hundred MW).

For example, the consumer may be an offshore oil and/or gas platform, a large oil and/or gas production vessel, an offshoreconstruction site, or an offshore operation such as drilling or subsea compression/separation.

The consumer may be a small electrical power consumer (Such as a power consumer which consumes up to the order of one, ten, one hundred, or several hundred watts).

For example, the consumer may be a measurement instrument. The small power consumer, such as a measurement instrument or an aquaculture farm, may be mounted on the wind turbine.

The consumer may be external or remote from the floating Wind turbine.

The power consumer may be separate from the floating wind turbine. For example the power consumer mey be a separate unit.

The offshore wind turbine may be fully integrated with the consumer.

The consumer may be mounted oh the Offshore wind turbine.

The offshore wind turbine may comprise a power outlet. This power outlet may be for providing both the electrical energy from the generator and the electrical energy from the energy storage device to the consumer.

Transmissionlines, e.g. poWer transmission lines, may be connected to the offshore wind turbine for allowing the provision of the electrical energy to an external (s.e. remote or separate) consumer.

The wind turbine may be adapted to be used in Water depths of 50 to 1GQlm.

Several of the wind turbine! described herein may be used together to allow the provision of a larger amount Of, Or sufficient, power to a single or multiple power eohsumersv

The offshore wind turbine may be the sole power source for the consumer. Alternatively, the wind turbine may provide supplementary power, i.e. the electrical enetgy from the wind turbine may be in addition to electrical energy produced by, or on, the consumer or by other electrical energy generating devices. The other electrical energy generating devices may be other floating wind turbines.

The present invention may provide a spar buoy floating wind turbine for providing electrical energy to a power consumer, the floating wind turbine comprising a wind turbine generator for generating electrical energy for the power consumer from wind energy, an energy storage device for providing electrical energy for the power consumer and a fuel (e.g. diesel) generator for providing electrical energy for the power consumer. The energy storage device andfbr the fuel genefatof may be housed within the floating structure and may provide at least some of the balance weight of the spar buoy floating wind turbine.

The present invention may provide a Spar buoy floating wind turbine: for providing electrical energy to a power consumer, the floating wind turbine comprising a wind turbine generator for generating electrical energy for the power consumer from wind energy, an energy storage device for providing eiectrical energy for the power consumer and a solar system for providing electrical energy for the power consumer. The energy storage device may be housed within the floating structure and: may provide at least some of the balance weight of the spar buoy floating wind turbine.

Th© present invention may provide a system which comprises the above described floating wind turbine and the above described consumer.

The present invention may also provide a method of providing electrical energy to a power consumer, the method comprising: providing an offshore wind turbine for providing eiectrical energy to a power consumer, the offshore wind turbine comprising: a generator for generating electrical energy for the power consumer from wind energy, and an energy storage device for providing electrical energy for the power consumer.

The method may be a method of reliably providing power to a power consumer. This is because, the provision of the energy storage device means that it is possible to provide electrical energy for a given period of time (such as about one week) irrespective of the environmental conditions, e.g. wind speed.

The method may comprise providing the above described offshore wind turbine. The wind turbine provided may comprise one or more of the above described optional features:;

The method may comprise operating the offshore wind turbine.

The method may comprise using the generator to generate electrical energy for the consumer from wind energy. The method may comprise providing electrical energy from the energy storage device to the consumer.

The method may comprise providing electrical energy generated from the Wind energy and electrical energy from the energy storage device to a power consumer.

The method may comprise charging the energy storage device using electrical energy which has been generated in the Wind turbine generator.

Any number (e.g. two or more| of the above described optional features may be combined in an embodiment.

With the present invention, because it is possible for electricaI energy to be provided to a consumer from at least the Wind turbine generator and an energy storage device it is possible for a constant amount of electrical energy or at least a minimum amount of electrical energy to be provided reliable for at least a given oeriod of time (such as one week). This is because the at least two sources of electrical energy may complement and/Or supplement each other.

Certain preferred embodiments of the present invention will now be described by way Of example only with reference to the accompanying drawings, in which:

Figure 1 is a schematic of a wind turbine; and

Figure 2 is a schematic of a wind turbine connected to a consumer

The exemplary wind turbine 1 shown in Figure 1 is a spar buoy type floating wind turbines, although the wind turbine could be any type of floating wind turbine for use bffShore.

The Wind turbine 1 comprises a support structure 2. The support structure 2 comprises a tower 4, a transition pie|e 5 and a foundation 6 on which the tower 4 is mounted via the transition piece 5. The portion of the foundation 6 which is below the water line 8 may be referred to as the lower substructure.

Within the foundation 6 there is balance weight 7 which is used to help Keep the floating wind turbine 1 upright. The balance weight may comprise permanent ballast, fixed ballast and water ballast in addition to other components housed Within the foundation 6; which are discussed in more detail below. A nacelle 10 is located on the tower 4. The nacelle 10 houses a wind turbine generator 26 (see figure 2) for generating electrical energy from wind energy. Attached to the nacelle 10 is a plurality of rotor blades 12. The action of the wind; may cause the rotor blades 12 to turn which, by means of the generator housed in the nacelle 10, can generate electrical energy from wind energy. This electrical energy may be provided to a consumer 20 and/or be used to power equipment housed within the wind turbine 1 (such as to charge: ansenergy storage device 18).

The floating wind turbine 1 is arranged to provide electrical eneiiSy to a consumer 20, the electrical energy comprises electrical energy other than electrical energy which has been generated from wind energy. The electrical energy other than electrical energy which has been generated from wind energy may be provided by equipment which is housed within tie foundation 6 of the floating wind turbine 1.

This equipment comprises an energy storage system 18. The equipment may optionally·· also comprise one or more of a fuel (such as diesel) generator 18 and a solar system (which may comprise photovoltaic cells) 24.

Thus, the floating wind turbine is able to provide electrical energy which has not been generated from wind energy or not been generated in the wind turbine generator attached to the rotor 12 to the consumer 20.

This floating wind turbine 1 may be aisle to provide 0.1 MW to 10MW and may be used in a water depth 10 to 1000 m. the energy storage system 18 may be used to provide supplemental power to a consumer 26; for e>campie when the wind speed is low Or the consumer 20 temporarily requires more electrical than can be provided from the wind turbine generator 26 alone;

The floating wind turbine 1 is arranged to generate electrical energy from a further second energy source (further to the wind energy used by the wind turbine generator) which can be provided to the consumer^ This is achieved using art energy storage device 18 and optionally a fuel generator 16 (such as a diesel generator), and/or a solar system 24. Although not shown, the floating wind turbine 1 may also house a fuel tank which contains fuel used ip the fuel generator 16,

The energy storage device 18 may be one or more batteries. These batteries 18 can be used to store energy converted from wind energy and/or a different energy source by the wind turbine 1. these batteries 18 can also be used to provide electrical energy to the consumer 26,

Although not shown, the floating wind turbine 1 can have an outlet which can deliver eiectricai energy generated on the Wind turbine 1 to the consumer 20.

The electrical energy delivered to the povwer consumer 20 via the power outlet may be generated from Wind energy or generated from a second energy source (which may comprises solar energy and fuel or the energy storing device 18). Thus wind turbine 1 may be able to reliably provide electrical energy to the power consumer even if the wind speed is low or Wto.

The equipment, (which may comprise at least part of at least one or more of the energy storage system 18, the fuel (such as diesel) generator 16. or a solar system 24) can be used as part of the balance weight of the floating wind turbine 1.

Figure 2 shows schematically the arrangement of some of the components in a floating wind turbine 1. the floating Wind turbine comprises a wind turbine generator 26. This generator 26 may be located in a nacelle 10 and connected to a rotor 12.

Connected electrically between the wind turbine generator 26 and the consumer 20 may be a frequency converter 28 and then a wind turbine transformer 31

The wind turbine 1 may be connected to the consumer 20 via a transmission line 34.

This embodiment of the floating wind turbine 1 comprises an energy storage device 18, such as a battery pack.

The energy storage device 18 may be Connected to the power generation system at various locations as illustrated by the dotted lines 31, 32 or 33.

The first option 3 Τ' is for the energy storage device 18 to be connected to the system at the frequency converter 28, as shown by line 31. in other words, the energy storage device 18 may be electrically connected to the wind turbine generator 26 in the frequency converter 18. For example, the energy storage device 18 may be directly connected to the frequency converter 28 which is connected to the wind turbine generator 26.

Alternatively, as shown by line 31, the energy storage device 18 may be electrically connected to the wind turbine generator 26 on the lower voltage side (e.g. a low voltage side) of the transformer 30. The energy storage device 18 may be connected between the frequency converter 28 and the wind turbine generator transformer 10,

Alternatively, as shown by line 33, the energy storage device 18 may be electrically connected to the wind turbine generator 26 on the higher voltage side (e.g. a medium voltage side) of the transformer 30. More specifically, the connection may be between the wind turbine transformer 30 and the consumer 20.

Claims

CLAIMS:

1. A floating wind turbine for providing electrical energy to a power consumer, the floating wind turbine comprising: a generator for generating electrical energy for the power consumer from wind energy, and an energy storage device for providing eiectricaJ energy for the power consumer.
2. A floating wind turbine according to claim 1, wherein the floating wind turbine is arranged to provide at least a predetermined minimum amount of electrical power for the power consumer for at least predetermined period of time.
3. A floating wind turbine or i, wherein the energy storage device is housed Within a supped structure of the floating wind turbine.
4. A floating wind turbine according to claim 1, 2 or |, wherein the floating wind turbine comprises a balance weight and wherein the energy storage device provides at least part of tie balance weight of the floating wind turbine
5. A floating Wind turbine according to any preceding claim, wherein the wind turbine comprises a frequency converter, and wherein the energy Storage device is electrically connected to the generator for generating electrical energy for the power Consumer from Wind energy in the frequency converter:
6. A floating Wind turbine according to any of claims 1 to 4, wherein the wind turbine comprises a wind turbiie generator transformer, and wherein the energy storage device is electrically connected to the wind turbine generator on the lower voltage side of the transformer.
7. A floating wind turbine according to any of claims 1 to 4, wherein the wind turbine comprises a Wind turbine generator transformer, and wherein the energy storage device is electrically connected to the wind turbine generator on the higher voltage side of the transformer. 8; A floating wind turbine according to any preceding claim, wherein the generator and the energy storage device each comprise: a controller and wherein the controllers are integrated.
9. A floating wind turbine according to any preceding claim, wherein the floating wind turbine comprises at least one second generator for generating electrical energy from an energy source other than wind. 10 A floating wind turbine according to claim 9, wherein tie second generator comprises one or more solar photovoltaic ceils and/or one or more fuel heat or pressure driven generators.
11. A floating Wind turbine according to any preceding claim, wherein the energy storage device comprises a battery.
12, A floating Wind turbine according tb any preceding claim, wherein the floating wind turome is a spar buoy floating wind turbine. 13 A method of providing electrical energy to a power consumer, the method comprising: providing an offshore wind turbine for providing electrical energy to a power consumer, the offshore wind turbine comprising: a generator for generating electrical energy for the power consumer from wind energy, and an energy storage device for providing electrical energy for the povpr consumer:
14. A method according to claim 13, wherein the offshore wind turbine is the offshore wind turbine of any of claims 1 to 12.
15. A method according to claim 13 or 14, wherein the method comprises using the generator to generate electrical energy for the consumerIromwind energy and providing electrical energy from the energy storage device for the consumer. 16A method according to claim 13,14 or 15, wherein the method comprises charging the energy storage device using electrical energy which has been generated in the wind turbine generator.
17. A method according to any of claims 13 to 18, wherein the method comprises providing at ieast a predetermined minimum amount Of electrical power for the power consumer for at least predetermined period of time.