GB2383204A

GB2383204A - Offshore wind driven generator

Info

Publication number: GB2383204A
Application number: GB0123161A
Authority: GB
Inventors: Morrough Kavanagh Geoffrey Mc
Original assignee: ULTRAMARINE CORP
Current assignee: ULTRAMARINE CORP
Priority date: 2001-09-26
Filing date: 2001-09-26
Publication date: 2003-06-18
Also published as: GB0123161D0

Abstract

A method and apparatus for generating electrical power from the wind at remote offshore sites taking advantage of the strong and more consistent winds found at a considerable distance from the shore. The power is generated from a plurality of wind turbines 4 deployed on vessels 1 anchored semi-permanently offshore, and stored in accumulators or batteries on a floating charging station (11 in figure 2). The charged accumulators are exchanged for empty accumulators, and the charged ones shipped to shore for discharge into a national grid. Preferably the vessel is a catamaran anchored at one end only, such that it will naturally turn into the wind.

Description

Power Generation From the Wind The present invention is concerned with the generation of power from the wind.

The generation of power from the wind via various types of wind turbines is well known and subject to a number of difficult problems, in particular, there are a limited number of sites where the environment makes wind power generators suitable, i. e., unoccupied sites where land costs, and wind strength, can be forecast able to generate power at all economically. Most such sites are already occupied or are sites of exceptional natural beauty such that proposals to construct wind power generators meet with strong objections further escalating costs. From a technical perspective such sites are rarely where the power is actually needed and are often difficult to access in the event the construction does take place. The wind strength at such sites may on average be suitable but is often in fact very variable so that power generation will be an intermittent activity. A recent proposal to alleviate some of these problems is to site generators in coastal waters on platforms founded on the seabed. Such generators must be located sufficiently close to shore to transmit the generated power via cable without excessive losses. However, such generator sites again meet with many of the problems common to land based sites mentioned above, and the cost of building foundations on the seabed is high.

A further problem which has recently become apparent and is likely to become commonplace in future is that experienced by California where very rapid economic growth has resulted in a large increase in power demand, while various constraints imposed upon the power utilities have prevented the utilities from constructing plant able to meet the rise in demand. There is thus a demand for a large scale portable

power generating facility to meet unanticipated short to mid term demand at various locations as required.

The present invention provides a method of power generation comprising the steps of, deploying a wind power generator offshore, generating electrical energy from the wind, storing the electrical energy generated in an adjacent portable accumulator the accumulator reaches a desired capacity, transporting the accumulator to an onshore port facility, docking the accumulator with the onshore port facility whereby the accumulator is connected for discharge into an electrical power distribution grid.

The present invention avoids the need to connect an offshore power generation facility to a shore based distribution grid by cables and so avoids the very considerable expense and technical difficulty associated with stringing cables even under relatively short spans of water, of the order of less than ten kilometres. The preferred form of storage facility is a recently developed large scale electrochemical accumulator known as Regenesys TM. Other systems of energy storage might be used but the Regenesys system has the required capacity to accumulate, store and deliver electric power in a modular portable accumulator. Details of the system are available from www. Regensys. com and are the subject of patent applications. In essence the Regenesys system stores power from a conventional electrical source by means of a reversible electrochemical reaction which takes place in a regenerative fuel cell. The two charged electrolytes are then stored in separate tanks. Capacity is dependent on the mass of electrolyte stored and commercial storage plants are possible in the range from 5-500MW.

It is envisioned that accumulators will be installed either in containers to be conveyed from the charging station onto an appropriately adapted container vessel, or a vessel

consisting primarily of the accumulators will dock directly with the charging station until the inboard units are charged, and will then ship the charged units to shore for discharge on demand into the land based distribution grid. This method thus allows the power generating facility to be located many kilometres offshore, e. g. 20-150km and perhaps more. Power generation facilities so far offshore are much less likely to meet with strong political and environmental objection. A further important advantage is the possibility of locating the generating facility at locations where wind strength is particularly consistent.

It is possible that such offshore facilities may be founded on the seabed, and use may be made of obsolete oil or gas rigs where opportunity arises. However, the preferred manner of power generation is by the use of very large generator vessels semi permanently anchored to the seabed. Preferably the vessels will be constructed from the two hulls of pre-existing ships secured together to form a catamaran. A catamaran with a hull separation of 1.5 times the individual beam of either vessel [PK1]provides a generator vessel with sufficient lateral stability to mount a large wind power generating facility. Conveniently, there is presently a fleet of very large vessels comprised of singles skinned oil tankers which are still serviceable but unusable in their original duty because of changes to safety regulations.

Each generator vessel is anchored by the bows only, so that it naturally turns into wind. Wind power generators provided by turbines can thus be mounted for rotation about horizontal axes facing the bows and no further provision needs to be made for turning the turbines into wind. Thus a superstructure which mounts the turbines high above the hull or hulls can be rigidly mounted to the deck or decks and so can be relatively strong and light. This in turn permits the use of very large turbines and makes coupling the generators mechanically and electrically to the hull relatively straight forward.

Each generator vessel is expected to be capable of generating about 5MW.

To provide greater generating capacity the method envisions anchoring a number of similar vessels in close proximity, each connected to a common charging station.

Thus ten generator vessels can be connected in a group to a single charging station to generate of the order of 50MW.

A generator vessel and a method for wind power generation embodying the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figures 1A-1C are diagrammatic drawings of a generator vessel in front elevation, side elevation and plan respectively, Figure 2 illustrates the offshore components of a wind power generating facility, and Figure 3 illustrates the onshore components of a wind power generating facility.

Figures 1A to 1 C show a generator vessel comprising two large hulls 1, such as may conveniently be provided by the presently redundant fleet of single skin oil tankers.

The hulls are connected together by a bridging structure 2 which consists of a framework of beams and struts so that the hulls are separated by one and a half times the beam of either hull. This provides a sufficiently stable platform to support a superstructure. The superstructure comprises four"A"frames 3a 3b 3c and 3d arranged in pairs disposed in tandem from bows to stern of the generator vessel.

Each"A"frame is rigidly mounted with one leg attached to each hull and bridges from one hull to the other. The"A"frame has the benefit of providing a very tall structure and may have its apex of the order of 150-200m above the deck. This has various benefits including the presentation of the turbines to the stronger winds at altitude

above sea level and keeps the turbines and generators away from the waves and spray.

Turbine sets 4 each consists of five wind turbines 5a, 5b, 5c, 5d, 5e arranged to rotate on a common drive shaft 6 to drive a generator 7. Five turbine sets 4 are supported extending horizontally fore and aft between each pair of"A"frames with one set 4a disposed at the apex of the"A"frame and the others disposed beneath.

The generator vessel is anchored at the bows 8 only to a permanent seabed anchor 9 so that the generator vessel will swing bows into wind. Occasionally single generator vessels may be all that is required in which case a charging station 11 may be provided on board. The charging station is arranged to receive power from the generators and use it to charge Regenesys type accumulators 10. When fully charged the accumulators are transferred to a shuttle ship 12 and shipped to a shore station for discharge as required.

In most circumstances more than one generator vessel will be required to meet the power demand. In this case, as shown in figure 2 a fleet of generator vessets"G"may be grouped together to deliver power via conventional cables to a single charging station 11. The shuttle vessels 12 then dock only with the charging station 11 to unload discharged Regenesysllv type accumulators to the charging station and to load charged accumulators for delivery to the shore station. The arrangement where only a single charging station is used allows a large number of generator vessels G to be used in relatively close proximity without causing undue hazard to the shuttle vessels which need never approach the generator vessels. In figure 2 the group of generator vessels are arranged with their moorings at the nodes of a rectangular grid spaced to allow each to swing through 360 degrees. However, the structures are equally likely to be arranged to take best advantage of the wind.

The shore station shown in figure 3 comprises a dock for unloading Regenesys type accumulators 10 and connecting each to a distribution station 13 for discharge into a power grid 14. Facilities are also provided for loading discharged accumulators onto the shuttle vessel 11. Although the accumulators discharge direct current, the technology to convert to alternating current exists and would commonly be implemented at the shore station.

The Regenesys accumulator system stores power by the regeneration of two separate electrolytes. It may therefore only be necessary to transport the electrolytes between the charging station and the shore station in suitable tanks. Fuel cells which charge the electrolytes and discharge the electrolytes can thus remain permanently at each of the charging station offshore or the shore station and all that may need to be shipped is tanks of electrolyte. This presents the possibility of simply pumping charged or discharged electrolyte into tanker type shuttles at each of the charging station and the shore station. In this instance the Regenesys type accumulator comprises a pair of tanks, for electrolyte storage, adapted either to be loaded on and off a shuttle vessel, or a shuttle vessel with tanks for the electrolyte inboard which can be filled with loaded electrolyte from pipe connections to the Regenesys fuel cell. The fuel cell is a permanent part of the charging station with a similar fuel cell provided at the onshore discharge station.

Claims

Claims 1. A method of power generation comprising the steps of, deploying a wind power generator offshore, generating electrical energy from the wind, storing the electrical energy generated in an adjacent mobile accumulator connected to a charging station until the unit reaches a desired capacity, transporting the accumulator to an onshore port facility, docking the accumulator with the onshore port facility whereby the accumulator is connected for discharge into an electrical power distribution grid.
2. A method of power generation according to claim 1 comprising the steps of, discharging the accumulator, transporting the accumulator to the, or another, offshore wind power generator, connecting the accumulator to a charging station adjacent the wind power generating facility, and recharging the accumulator.
3. A method according to any one of the preceding claims including the steps of mounting the wind power generator on a generator vessel, and anchoring the structure so that the movement of the structure around the anchor follows changes in wind direction to maintain the wind power generator in an into wind direction.
4. A method according to claim 3 comprising the step of constructing the generator vessel from two pre-existing ships secured together to form a catamaran.

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5. A method according to one of claims 3 or 4 comprising the steps of anchoring a plurality of the generator vessels together in close proximity each bearing a wind generator providing a single charging platform, and delivering power from each wind generator to the charging platform via an electrical power transmission grid.
6. A generator vessel for use in generating power from the wind offshore, said generator vessel having a superstructure which is rigidly mounted to the deck to support a wind turbine permanently aligned with the bows of the generator vessel and coupled to a generator to provide a wind power generator.
7. A generator vessel according to claim 6 wherein said wind power generator is capable of generating 100kW.
8. A generator vessel according to claim 7 wherein the wind power generator is capable of generating 1 MW.
9. A generator vessel according to claim 6 wherein the wind power generator is capable of generating 5MW.
10. A generator vessel according to any one of claims 6 to 9 wherein the generator vessel comprises at least two conventional ships hulls secured together abeam

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11. A generator vessel according to claim 10 wherein the hulls are separated by a distance equal to one and one half times the beam of one hull.
12. A generator vessel according to any one of claims 6 to 11 wherein the wind power generator comprises a plurality sets of co-axial wind turbines supported on the superstructure.
13. A generator vessel according to claim 12 wherein the superstructure supports two or more sets of turbines with their axis at different heights.
14. A generator vessel according to claims 12 or 13 wherein the sets of turbines are arranged in tandem.
15. A generator vessel according to any of claims 6 to 14 wherein the superstructure comprises an"A"frame.
16. A method of generating power from wind offshore as herein described.
17. A generator vessel for generating power from the wind as herein described with reference to the accompanying drawings.