WO2009136784A1

WO2009136784A1 - Device for generating energy

Info

Publication number: WO2009136784A1
Application number: PCT/NL2009/050197
Authority: WO
Inventors: Alexander De Coninck
Original assignee: Alexander De Coninck
Priority date: 2008-05-07
Filing date: 2009-04-14
Publication date: 2009-11-12
Also published as: NL1035400C2; EP2334928A1

Abstract

The invention relates to a device for generating energy, comprising: a frame with at least two floats for positioning the device on a body of water with a flow under the frame, and with a span structure on the floats, and at least two blade wheels under the span structure which are connected individually or in combination via at least one shaft to at least one generator in, at or on the frame, and the blades of which extend at least partially into the body of water.

Description

DEVICE FOR GENERATING ENERGY

The present invention relates to a device for generating energy, in particular electrical energy, on a frame. The frame comprises at least two floats for positioning the device on a body of water with a flow under the frame and with a span structure on the floats. Arranged under the span structure are at least two blade wheels which are connected individually or in combination via at least one shaft to at least one generator in, at or on the frame. The blades further extend at least partially into the body of water. In the case of a flow under the frame the blades are driven, which in turn causes the shafts to rotate, as a result of which the generators are enabled to generate electric power. It is known in the art that floating devices can be positioned on bodies of water in order to generate electric power using water wheels or blade wheels. In each of the known cases, however, a single blade wheel is used. In upward direction, as seen from the body of water, these known devices are such that the single blade wheel can be accessed freely toward the top in the space.

The known devices therefore generate hardly enough power to be able to provide a cost-effective device. The known devices moreover also cause much nuisance. The blade wheels are often of large size in a futile attempt to still enable generation of considerable power, while this results in excessive annoyance. The known devices for instance create noise nuisance, this drawback being particularly manifest in applications on for instance rivers. The present invention provides a device with the combination of features as summarized above and defined in the main claim of the appended set of claims. If a sufficient number of blade wheels covered by the span structure are placed in a flow, the total electric power which can be generated with the device is in fact almost unlimited, and good measures can be taken to combat annoyance and noise nuisance, if not to be rid of them completely. The present invention has many different preferred embodiments as are defined in the dependent claims of the appended set of claims . It is thus possible for the blade wheels to be positioned adjacently of each other in the flow. An array of blade wheels is thus formed transversely of the direction of flow. In a case where a single one of the blade wheels then fails or defects occur, this cannot prevent the whole device being able to continue functioning per se for the purpose of generating electric power. For maintenance and replacement purposes the blade wheels can further be releasably connected to each other in groups or several units. A releasable coupling can be formed by a flange coupling between the shaft and an adjacent shaft of an adjacent group of blade wheels or a single blade wheel. The blade wheels can thus be kept relatively small, whereby the individual influence on the ultimate effectiveness of the device can be limited, as well as its susceptibility to malfunction. The blade wheels can further be replaced individually or in groups, and because use can be made of smaller blade wheels the effort and the cost of transporting an individual blade wheel will also remain limited. The overall device can nevertheless be expanded almost without limit in order to achieve a desired power that can be generated using the device. In an embodiment with mutually adjacent blade wheels, at least one suspension for the shaft between the blade wheels can further be provided between the blade wheels or between groups of blade wheels. The stability of the assembly of mutually adjacent blade wheels can thus be improved. Such a suspension can extend from the span structure, but can also be arranged on a float floating on the body of water. This depends on the extent to which the overall device is immersed in the surface of the body of water and the control, to be further described hereinbelow, with which such a "draught" can be set or adjusted. The suspension can preferably also comprise a bearing so that the shaft can rotate freely with at least two blade wheels thereon.

Additionally or alternatively it is possible for the blade wheels to be placed one behind another in the flow. This provides an extra dimension to expanding of the device and the power to be generated therewith. With blade wheels which are positioned or arranged substantially one behind another, a number of further measures can be taken to utilize the flow with maximum efficiency. It is thus possible to envisage a venturi-like inlet opening or a venturi passage for the purpose of generating a maximum flow rate in the flow for driving the blade wheels. In an embodiment with blade wheels arranged or positioned mutually adjacently as well as one behind another, it can be advantageous to position the blade wheels offset relative to each other in the flow. The flow thus has the opportunity to overcome as much turbulence and as many other influences of a blade wheel as possible in the flow direction, and the flow can stabilize in the intermediate space between blade wheels lying one behind another, which can produce a further increase in output.

In an alternative or additional embodiment the device according to the invention can have the feature that the blades of the blade wheels are curved. In such an embodiment a maximum efficiency can be achieved from the flow because the blade wheels can be placed more deeply in the body of water than heretofore.

In another additional or alternative embodiment the device can have the feature that at least one inlet grid is arranged on the frame in the flow in front of the blade wheels. It is thus possible to prevent driftwood or other possibly damaging elements being able to get into or between the blade wheels. This also applies for larger and possibly endangered species of fish or other animal species. Smaller animals can swim between the offset blades without (too great) a danger of injury and/or damage to the device.

In a further additional or alternative embodiment, which is particularly advantageous in combination with an inlet grid, a bridge can be arranged on the front side of the frame below the span structure. Driftwood and other elements at the inlet grid can be removed from such a bridge. Such a bridge can also extend further to the rear, transversely over the device between the floats, for instance for maintenance to the blade wheels or the shafts. In a further additional or alternative embodiment the device can have the feature that a closing element which can be selectively actuated is arranged between the floats and in front of the blade wheels in the direction of flow. When the flow becomes too strong and there is imminent danger of damage to the device, such a closing element can be closed. Such a closing element can for instance be a door, or a hatch in general. When such a door, hatch or other closing element is partially closed, it can function as a wave surge breaker or damper in order to prevent damage to the device due to strong wave surge.

In a further additional or alternative embodiment the device can have the feature that a closed connecting member is arranged between the floats and under the blade wheels. The flow under the blade wheels can thus be properly channelled in order to obtain a good output from the flow. Such a connecting member can also comprise openings for the purpose of pushing up water from the flow which would otherwise flow under such a connecting member. An increase in output can thus be realized by the continuous feed of more and more water from the flow. The connecting member can moreover also have curving forms, wherein the curves are adjusted to the contours of the blade wheels. Diverging and converging variations can moreover also be provided in the connecting member relative to the contours of the blade wheels, and in some embodiments this results in venturi passages along the blade wheels and thereby increases the flow speed of the flow along the blade wheels, and thus also improves the output . In a further alternative or additional embodiment the device according to the invention can have the feature that flow guides are arranged which extend transversely of the flow and which are orientated upward in the direction of the flow. Such flow guides have already been mentioned above in relation to the presence of a connecting member, although even without closed connecting member such flow guides can be utilized with favourable effect for the purpose of pushing up the flow to the blade wheels. In such an embodiment the flow guides can also have a wave form with peaks and valleys in side view and in the direction of flow, whereby a good guiding of the flow along the blade wheels can be improved, although without a closed connecting member necessarily being required for this purpose.

In a further preferred embodiment, which is referred to as an addition or as an alternative, the device can comprise a wind turbine of a random type. This can for instance be placed on the span structure or extend laterally from at least one of the floats. The positioning of the wind turbine is less relevant, although the contribution toward the increase in the output of the overall device is here the purpose of the measure. A wind turbine is connected or can be connected to the same generator as the generator or at least one of the generators applied in combination with at least one of the blade wheels. An additional generator need not therefore necessarily be provided in addition to the battery of generators already present in an extended embodiment of a device according to the present invention. An additional or individual generator can on the other hand be provided in combination with the wind turbine. Despite different forces driving the wind turbine and the blade wheels, simple transmissions can be utilized.

In a further alternative or additional embodiment the device can have the feature of at least one ballast tank, preferably even two or more tanks, which is preferably associated with a control and under its control. The control can further be connected to a sensor or sensor means for determining the depth to which the blade wheels protrude into the body of water. The control can then control the ballast tank such that the blade wheels protrude to a desired depth into the body of water. Such a measure in respect of ballast tanks contributes toward increasing the output of the overall device because the depth to which the blade wheels protrude into the body of water determines the output for each of the blade wheels. In a further additional or alternative embodiment a machine room with at least one generator can be arranged in the frame. A highly suitable location herefor is the span structure, or at least a machine room at the level of the span structure. Possible flooding of such a machine room, as would be the case if the generators were placed at the level of the blade wheels, can thus be prevented with a high degree of certainty. Such a machine room at the specified height has the consequence that, between the shaft or shafts on which at least one blade wheel is arranged, a transmission is required in each case for connecting the shaft or shafts to the generator or generators. This is because the height difference has to be bridged, although this can be realized with very simple means such as cables or chains and reversing wheels or toothed wheels, this also at a transmission ratio which can be favourable for the output of the generator. Generators, transmissions and other heavy and/or large components can be arranged balanced and/or parallel or proportional to SB and/or BB. In a further additional or alternative embodiment the device can be formed such that a control room is arranged in or on the frame having at least a part of a control for controlling components and elements of the device. The control room can for instance be arranged on top of the span structure, with an unobstructed view over the surrounding area. It will most probably not be the intention for a control room to be continuously manned, although this is not precluded. However, if the device according to the present invention is manned, it then has evident advantages if there is a view over the surrounding area from the control room.

In a further additional or alternative embodiment the device can be formed such that at least a part of the frame comprises sound insulation. Nuisance for the area surrounding the device can hereby also be further abated, to the extent this is necessary after providing the measure of the span structure over the blade wheels. Even with the span structure the sound insulation, for instance in the floats and in the span structure, can reduce the noise nuisance even further. In yet another additional or alternative embodiment a device according to the invention can have the feature that at least one of the blade wheels is connected to the generator by means of a transmission which can be selectively actuated. When the transmission is switched off, maintenance can be carried out on a generator which might otherwise suffer irreversible damage if a defect occurs in the generator and the flow continues driving the shaft or shafts via the blade wheel or the blade wheels connected to this generator.

The invention will be further described hereinbelow on the basis of preferred embodiments thereof and with reference to the accompanying drawings, wherein various embodiments are shown only by way of example, and therefore not limitative of the present invention, in which embodiments the same reference numerals are used for the same or similar parts, components and features, and in which: fig. 1 shows a perspective view of a device according to the present invention in use; fig. 2 shows a top view of a device according to the present invention; fig. 3 shows a partly cut-away top view of the device in fig. 2; fig. 4 shows a front view of the device in fig. 1 according to the present invention; fig. 5 shows a view of parts in a small embodiment of a device according to the present invention, such as that of fig. 1; fig. 6 shows a partly cut-away side view of a device according to the present invention; fig. 7 shows a partly cut-away perspective view of a small embodiment of a device according to the present invention; fig. 8 shows a detail of several parts and components of a device according to the present invention; fig. 9 shows a top view corresponding closely to fig. 8; fig. 10 and fig. 11 each show a view of an embodiment of a blade wheel according to the present invention, wherein fig. 12 shows a part of the blade wheel of fig. 11 in more detail; and fig. 13 shows an alternative embodiment of a blade for a blade wheel.

Fig. 1 shows a device 1 for generating electric power as an embodiment of the invention. Device 1 comprises a frame 2 with two floats 3, 4 on either side of the device relative to a flow direction A in a body of water. A span structure is arranged over the two floats, wherein blade wheels are arranged between floats 3, 4 and span structure 5. In the schematic view of fig. 1 two blade wheels 6, 7 are arranged in line, with an additional blade wheel 8 therebehind. The in-line blade wheels 6, 1 are connected via a shaft 9 to generators in frame 2 to be described further hereinbelow.

A wind turbine 10 and solar panels 11 are further arranged on span structure 5 of frame 2. Also arranged on span structure 5 is a control room 12, in which can be located computer systems and other control elements which are substantially not further described here.

It is further noted that a bridge 13 is arranged under span structure 5. Bridge 13 has a railing 14 and extends above blade wheels 6, 7 and 8. Further arranged under bridge 13 is a grid 15 which serves as barrier to water litter and other possibly harmful elements before they reach blade wheels 6, 7 and 8 along with flow A.

Fig. 2 shows a top view of the present invention. Wind turbine 10 and control room 12 can also be seen here. To the side of device 1 relative to flow direction A an equipment vessel 16 is moored to a landing-stage 17 so that device 1 according to the invention can be provisioned and workers can be transported from and to device 1 for maintenance etc. A hatch 19 is arranged adjacently of control room 12 in upper deck 17 of the device. This hatch can be opened for the supply and removal of components such as generators, blade wheels and so on, which can be taken from equipment vessel 16 and loaded into device 1 via hatch 19, and vice versa, using a hoisting installation, for instance a schematically shown crane beside wind turbine 10. Crane 18 is then preferably longer. Parts and components from equipment vessel 16 can also be placed beside the hatch using different means, after which hatch 19 can be opened and the parts and components can be lowered into the hatch using crane 18. Device 1 can be placed in a ship dock for structural maintenance. The dimensions of device 1 are preferably not made greater than dimensions at which maintenance in a dock is still possible. It is however by no means precluded for a device 1 according to the invention to have larger dimensions, this depending on the intended application and the intended effectiveness or the intended output thereof.

On the deck of device 1 as shown from the top side in fig. 2, bollards 20 are further arranged at the corners to allow mooring of equipment vessel 16. Such bollards 20 can also be arranged on landing-stage 17. Winches 21 are further situated adjacently of bollards 20.

Fig. 3 shows a partly cut-away top view corresponding to the view of fig. 2 tilted through 9OD. This relates substantially to the manner in which the blade wheels are connected to shafts for driving generators (not shown) .

Ballast tanks 22 are arranged in floats 3, 4 of device 1. The depth to which blade wheels 6, 7 and 8 protrude into the water surface of the body of water flowing under device 1 in a flow direction A can be influenced by a suitable control of the water level in ballast tanks 22.

The blade wheels 6, 7 in a row are mutually connected with a drive shaft 23. Suspension points 24, preferably in the form of a bearing, can be provided in the sequence of the array of blade wheels with the drive shaft or drive shafts therebetween or therethrough. Suspension points 24 or bearings preferably have a connection to span structure 5, so that the shafts are suspended between the sequence in the array, this improving the rigidity and the strength of the assembled configuration of blade wheels 6, 7 and drive shafts 23. Coupling flanges 25 can also be arranged. The coupling flanges can serve to enable uncoupling of blade wheel sections with one, two or more blade wheels 6, 7 from the array and for instance replacement thereof. This may be necessary in the case of maintenance or replacement. The coupling flanges provide a particularly elegant and simple manner of dismantling blade wheel sections from at least one blade wheel at a time. Further shown is that grid 15 consists of three sections with two intermediate suspensions 26 for the grid parts between floats 3, 4.

It is also noted by the way that the skin 27 of device 1 according to the invention can consist of different materials. It is possible to opt for preserved steel, concrete or even a system referred to as G. P. S.

Fig. 4 further shows, albeit schematically, that insulating material 28 is arranged against the inner side of outer skin 27 of device 1. It is noted that as much of the outer skin 27 of the device as possible is covered with insulating material 28 in order to suppress annoying sound.

The view of fig. 4 shows clearly that a very large compartment is available between upper deck 17 and the underside 29 of span structure 5 for the purpose of placing machines such as generators 30. The coupling or connection between the drive shafts of blade wheels 6, 7, 8 to generators 30 is further described hereinbelow. It is noted that the drive shaft of wind turbine 10 also protrudes through upper deck 17 and is coupled to a generator in the compartment formed in span structure 5. At generators 30 use is made of a gearbox round reversing gearbox 31 in usual manner and where necessary. Such a box 31 forms a connection between a gear wheel and reverse gear 32, which is connected via a transmission to at least one drive shaft of an array of blade wheels 6, 7 or 8.

It has been noted above that device 1 can be trimmed with the ballast tanks in floats 3, 4, and fig. 4 clearly shows that the device can have a degree of height variation relative to the water level 33 of the body of water in which flow A occurs. Fig. 5 shows a relatively small device according to the invention which has limited dimensions of about 2.5 x 2 metres and which is light in weight, and can be manufactured from plastic and/or aluminium. The target group for this small, light device can be associated with undeveloped areas and inaccessible areas where water flow is available but electric power is not. This embodiment can also be used for military purposes, developmental aid, in inaccessible areas etc, and transport can for instance take place by helicopter. The operation of this relatively small variant is as follows. When it is placed in a water flow, the blades drive a 12V dynamo, thereby charging 12V batteries. 12V is converted into 220V via a converter, whereby the electric power can be utilized for diverse purposes such as communication, driving pumps, irrigation of agricultural land and so on.

In fig. 5 the height difference of fig. 4 is disregarded and the figure clearly shows that drive shafts 23 are suspended on one side in bearings 34 and on the other side protrude in watertight manner through a partition 35 and are connected to wheels 36. In the embodiment of fig. 5 three wheels 36 are mutually connected, for instance by means of a chain or belt or cable or the like. The rotating movement generated by the three drive shafts 23 in fig. 5 is transmitted via a separate transmission 37 to a dynamo 30 as possible embodiment of a generator. Also shown is that a rudder or keel is applied in order to hold device 1 straight in flow A.

Fig. 6 shows a further embodiment. This embodiment of fig. 6 has a number of additional or alternative features.

Grid 15 can thus be folded up in the direction of arrow B on the front side of the device. Grid 15 can also be folded down again to the active position thereof.

An up and downward movable wave surge breaker in the form of a hatch 38 is further shown. Hatch 38 can be moved up and downward within a range of movement in order to damp the wave surge coming in under device 1 in the direction of arrow A.

Fig. 6 shows other special features. The blades thus have curves on blade wheels 6, 7. This will be described further hereinbelow. Additionally or alternatively, guide surfaces 39 are further arranged under blade wheels 6, 7 and 8. A quantity of water is thus pushed upward to blade wheels 6, 7 and 8 from the body of water with flow A and is driven with even greater force in the direction of arrow C.

Fig. 3 also shows that lateral guide surfaces 40 are arranged for the purpose of guiding the flow A laterally to blade wheels 6, 7 and 8. It is further also noted that a winch 41 and a crane 42 can be utilized for manipulating grid 15. Fig. 7 shows that according to the present invention a small device comparable to that of fig. 5 can comprise a folding keel 43. A folding keel 43 is folded down when sufficient depth is available for this purpose under device 1. Use can be made here of a pull cable 44, which can in turn be coupled at some point to a winch (not further shown) .

Also shown is that batteries 45 are disposed in the intermediate space in span structure 5 for the purpose of storing generated electric power. Batteries 45 can optionally be replaced by a fixed land cable. The dynamo or generator 30 is also shown, wherein the transmission between blade wheels 6, 7 and 8 and generator 30 is also shown as a one-to-one relation. That is, a toothed wheel 46 at the free end of drive shaft 23 engages directly into a toothed wheel 47 connected to the drive shaft of the dynamo or generator 30. The dynamo produces a power at a voltage of for instance 12V, which can be converted to a voltage of 220V or any other voltage at random using a converter 48, which can likewise be arranged at the position of the compartment for machines in span structure 5, albeit at a lateral location above a float 3 or 4. Fig. 7 also clearly shows the feature that a connecting member 49 can be positioned under blade wheels 6, 7 and 8. Ballast tanks can be arranged therein, as in the case shown in fig. 7. Such a connection also allows the top side of connecting member 49 to take an articulated or curved form. Guide plates 39 have already been shown in Fig. 6, and these can be arranged in or on connecting member 49. In an alternative embodiment the top surface of connecting member 49 can have a curved form which can correspond closely to the design or at least diameter of blade wheels 6, 7 and 8, and also to the sequences of blade wheels one behind another in flow direction A thereof in order to enable flow A to be carried with a maximum effectiveness along each of the blades 6, 7 and 8 disposed one behind another. Fig. 8 shows several configurations for connecting drive shafts 23 to generators 30, and a drive shaft 50 of wind turbine 10 is also shown, which is in turn connected or coupled to a dynamo or other generator 51. More important here is the view of the number of drive shafts which is coupled in each case to a single generator 30. This number can be related to the designed generating power of each of the generators 30. On the left in fig. 8 three drive shafts 23 are connected to a single generator via a chain, for instance a type of Gall chain, via a tensioner 52. In the centre of fig. 8 only two drive shafts 23 are coupled to a single generator 30, while on the far right in fig. 8 only a single drive shaft 23 is coupled to a generator 30.

Grids 53 are arranged above blade wheels 6, 7 and 8. These can preferably be raised or lifted so that access can be provided to each of the blade wheels 6, 7 and 8. This can be favourable for maintenance and/or replacement in case of a defect. The flange couplings as described with reference to fig. 3 also serve for this purpose. Fig. 9 further shows on the left another configuration in which no less than five drive shafts 23 are coupled to a single generator 30 via a transmission 54, while four drive shafts are coupled to a single generator 30 via a transmission 54 on the right in fig. 9. It is also apparent, albeit schematically, that a watertight passage of the drive shafts at passage 55 is important. The manner in which drive shafts 23 are coupled to the generators is not important. This can be realized using chains, cables, fixed gear wheel transmissions and so on.

Fig. 10 shows a blade wheel 56. This blade wheel 56 consists of coupling plates 57 on drive shaft 23, wherein curved blades 64 can be arranged on coupling plates 57. In the case of flow A the blade wheels 56 can rotate in the embodiment shown in fig. 10 in a direction of rotation corresponding to the direction of clockwise rotation. Fig. 11 shows a closed embodiment with straight blades. That this is a closed embodiment is indicated by the arrangement of side plates 58. The blades are straight so that reversal of the direction of rotation can take place quite easily. Blades 59 are possibly arranged releasably as in the embodiment of fig. 10. This is shown by way of example in fig. 12, albeit that side panels

58 are absent here. Only blades 59 are here fixedly arranged or coupled on or to drive shaft 23 by means of coupling plates 57.

Fig. 13 then further shows that forward-extending flanges

60 can be applied. Passages 61 are also formed in blade plates 62 of fig. 13. It will be apparent that such blades 62 are exchangeable and can be mounted on a drive shaft or a section thereof. Coupling plates 57 can be used for this purpose, as in fig. 10.

It will be apparent that within the scope of the present invention many alternative and additional embodiments are possible relative to those described above and shown explicitly in the figures. The manner in which the devices according to the present invention can be immobilized has thus not yet been unambiguously defined. It will after all not be the intention to allow it to drift away on flow A. Fixed anchorings can be used. Such fixed anchorings inside or outside the periphery of the device then for instance each comprise a bollard and a plurality of anchorings, for instance four, can be used. The pole extends in vertical direction, and the device according to the invention can be moved up and downward therealong. If the flow direction changes, pivoting of the device is however difficult. Such a device can then preferably be placed in a flow which reverses direction at intervals, for instance a tidal flow. Depending on the available options and conditions, other per se usual means can also be utilized for immobilization purposes.

When the flow direction does not vary, as in a river, only means for bridging differences in water level possibly need be provided. It is possible to moor at the quayside, or immobilization can take place with bollards, anchors and/or mooring ropes. In a tidal flow the device can be moored fixedly and the direction of rotation of the blade wheels can be made variable. Corresponding modifications to the generators can be considered here, for instance by applying asynchronous three-phase generators and inverting one of the phases when the flow direction reverses, although it is also possible to implement reversible gearboxes.

In the case of a very strong flow A it is possible to provide the blades with strengthening ribs 63, as shown in fig. 12, although this is only one option. In the foregoing the blades of the blade wheels have been described in each case as fixed or detachable. It is however also possible to weld the blades fixedly to a drive shaft or a section thereof. As is usual in the shipping industry, such blades are also easy to replace simply by removing them from the drive shaft or section by machining, for instance using a grinder. In contrast to the view of fig. 6, the blades can be straight, particularly when the flow direction is reversible. The transmission in a gearbox to the generator can then also be adjusted accordingly.

It is also noted that the blade wheels can have a phase difference, at least in angular position during assembly, whereby the grip on the combined blade wheels by the water flow can be optimized. In the case of blade wheels with eight blades such a phase difference can amount to about 22.5DC.

Plates or grids which are removable or can be opened and walked on can further be arranged above the blade wheels, whereby visual inspection of moving parts can be realized or facilitated.

It is thus apparent that the various additional and alternative embodiments, as these may or may not be referred to or elucidated in the foregoing description, must all be deemed as lying within the scope of protection of the present invention, unless they depart from the letter or spirit of the appended claims.

Claims

1. Device for generating energy, comprising:

- a frame with at least two floats for positioning the device on a body of water with a flow under the frame, and with a span structure on the floats, and

- at least two blade wheels under the span structure which are connected individually or in combination via at least one shaft to at least one generator in, at or on the frame, and the blades of which extend at least partially into the body of water.

2. Device as claimed in claim 1, wherein the blade wheels are positioned adjacently of each other in the flow.

3. Device as claimed in claim 2, wherein of blade wheels disposed adjacently of each other a set comprising at least one blade wheel comprises in each case an associated shaft, and a shaft of an adjacent blade wheel or adjacent set of blade wheels is coupled releasably to the shaft associated with the set.

4. Device as claimed in claim 3, comprising a flange coupling between the shaft and the adjacent shaft.

5. Device as claimed in claim 2, 3 or 4, further comprising at least one suspension for the shaft between the blade wheels.

6. Device as claimed in claim 5, wherein the suspension comprises a bearing.

7. Device as claimed in claim 1, wherein the blade wheels are positioned one behind another in the flow.

8. Device as claimed in claims 2 and 7, wherein the blade wheels are positioned offset relative to each other in the flow.

9. Device as claimed in at least one of the foregoing claims, wherein the blades of the blade wheels are curved.

10. Device as claimed in at least one of the foregoing claims, wherein at least one inlet grid is arranged on the frame in the flow in front of the blade wheels.

11. Device as claimed in at least one of the foregoing claims, in particular claim 10, wherein a bridge is arranged on the frame below the span structure.

12. Device as claimed in at least one of the foregoing claims, wherein a closing element which can be selectively actuated is arranged between the floats and in front of the blade wheels in the direction of flow.

13. Device as claimed in at least one of the foregoing claims, wherein a closed connecting member is arranged between the floats and under the blade wheels.

14. Device as claimed in at least one of the foregoing claims, wherein at least one venturi passage is formed under the blade wheels.

15. Device as claimed in at least one of the foregoing claims, in particular though not solely claim 13, further comprising: flow guides extending transversely of the flow and orientated upward in the direction of the flow.

16. Device as claimed in claim 15, wherein the flow guides have a wave form in side view and in the direction of the flow.

17. Device as claimed in at least one of the foregoing claims, wherein a wind turbine is arranged on the device.

18. Device as claimed in claim 17, wherein the wind turbine is connected or at least can be connected to the same generator as at least one of the blade wheels.

19. Device as claimed in at least one of the foregoing claims, further comprising at least one ballast tank, and preferably at least two tanks, which is associated with a control and under its control, wherein the control is further connected to sensor means for determining the depth to which the blade wheels protrude into the body of water, and the control controls the ballast tank such that the blade wheels protrude to a desired depth into the body of water.

20. Device as claimed in at least one of the foregoing claims, wherein a machine room with at least one generator is arranged in the frame.

21. Device as claimed in at least one of the foregoing claims, wherein a control room is arranged in or on the frame having at least a part of a control for controlling components and elements of the device from the group comprising: safety means and indicators.

22. Device as claimed in at least one of the foregoing claims, wherein at least a part of the frame comprises sound insulation.

23. Device as claimed in at least one of the foregoing claims, wherein the generator is positioned at a position above the blade wheels with the substantially vertically oriented transmission between the shaft and the generator.

24. Device as claimed in at least one of the foregoing claims, wherein at least one of the blade wheels is connected to a generator by means of a transmission which can be selectively actuated.