Floating unit for energy harvesting

Abstract

The invention relates to a floating unit for energy harvesting. The floating unit can comprise: a vertical axis wind turbine (20), arranged to drive a first generator (21) via a wind turbine shaft (22), a water turbine (30) comprising a vertical hollow shaft (31) having turbine blades (33), the water turbine (30) is arranged to be powered by a water current and arranged to drive a second generator (32), a generator house (40) enclosing the first (21) and the second generator (32), the generator house (40) is arranged between the wind turbine (20) and the water turbine (30), a rod (34) that is suspended from the generator house (40) and passes through the center of the hollow shaft (31), and a stabilizing weight (35) arranged at the distal end of the rod (34).

Description

[0001] TITLE: Floating unit for energy harvesting

[0002] Field of the invention

[0003] The invention relates to a floating unit for energy harvesting and a floating installation comprising a plurality of said floating units.

[0004] Background of the invention.

[0005] There is a growing need for energy in the world and to be able to reduce greenhouse gas emission new energy should come from sustainable sources. Floating offshore wind is by many considered to be a major contributor to sustainable energy in the future. In order to realize more projects both investment costs and operating costs must be reduced.

[0006] Horizontal-axis wind turbines (HAWTs) in combination with a anchored spar buoy is so far the most common design for floating offshore wind. The diameter of the rotor and the height of the tower makes both installation and maintenance challenging and expensive. Entering such a floating installation for personnel is also challenging. The nacelle with the generator is located high above the water surface, so access to it is challenging. The nacelle is also very heavy, so the tower and the spar buoy must be dimensioned to handle this heavy weight high up above the water surface. Such design also calls for each installation to have independent anchoring and electrical transmission solution.

[0007] Increasing the power output compared to the amount of material used in the installations and in the infrastructure for the installations is essential to make floating wind economically viable.

[0008] Prior art:

[0009] US2018287461 AA discloses a apparatus and method of generating energy from renewable energy sources.

[0010] CN107829880A discloses a wind energy and tidal current energy electricity generating device. CN109973314A discloses a offshore floating wind-water synchronous generator set.

[0011] CN106121923A discloses a device for carrying out offshore tidal current energy and wind energy dual-purpose power generation through vertical shafts.

[0012] CN204961170U discloses a wind energy- trends can power generation facility.

[0013] Objects of the present invention

[0014] An object of the invention is to provide a floating energy harvesting unit that can harvest energy from both wind and water current.

[0015] Another object of the invention is to provide a solution to combine one or more wind turbine with one or more tidal turbine in a common floating installation having common anchoring.

[0016] Yet another object of the invention is to provide a solution to stabilize a floating installation with both a wind turbine and a tidal turbine.

[0017] Summary of the invention

[0018] In a first aspect, the invention relates to a floating unit for energy harvesting. The floating unit comprises: a vertical axis wind turbine, arranged to drive a first generator via a wind turbine shaft, a water turbine comprising a vertical hollow shaft having turbine blades, the water turbine is arranged to be powered by a water current and arranged to drive a second generator, a generator house enclosing the first and the second generator, the generator house is arranged between the wind turbine and the water turbine, a rod that is suspended from the generator house and passes through the center of the hollow shaft, and a stabilizing weight arranged at the distal end of the rod. The purpose of the stabilizing weight is to stabilize the floating installation to for instance prevent capsizing. Further the stabilizing weight helps maintaining the vertical orientation of the hollow shaft. Especially if the hollow shaft is long and extends far down into the water and the current is strong it requires a stabilizing weight to prevent it from being bent by the current.

[0019] Bearings can be arranged along the rod so that the hollow shaft can rotate easily without much friction between the rod and the hollow shaft.

[0020] The generator house can be arranged to provide buoyancy for the floating unit.

[0021] The water current can be a tidal current.

[0022] The generator house can be shaped as a hourglass having a narrow waist, wherein the generator house is arranged with its longitudinal axes parallel to the longitudinal axis of the vertical axis wind turbine.

[0023] Above and below the narrow waist are sections with more volume, those can be called bulbs or bulb sections, even though the end of the bulbs facing away from the waist can be flat.

[0024] The hourglass shaped generator house can have a circular radial cross-section.

[0025] The waist can have a maximal diameter that is less than half the diameter of the maximum bulb diameter, preferably between 0.5 and 0.25 of the maximum bulb diameter.

[0026] The floating unit is arranged to float so that the water surface reaches to the narrow waist section when it is submerged in water. To where on the floating unit the water surface reaches when it is immersed in water is determined by the weight and volume ratio. The orientation of the floating unit in the water is determined by the weight and volume distribution of the floating unit.

[0027] How deep the floating unit is submerged, can be configured / adjusted by using ballast, such as water in ballast tanks. The ballast tanks can for instance be near the bottom of the generator house. The advantage of submerging the floating unit to a depth where the water surface reached the narrow waist of the hourglass shape is that the cross sectional area of the floating unit at the water surface is small. So, that there is less volume in the splash zone being affected by waves and swells. The first and the second generator can be arranged above and below the narrower waist of the generator house where the is more internal volume and hence, room for the generator and affiliated systems.

[0028] A further advantage of an hourglass shaped generator house configured to be submerged so that the water surface reached the narrow waist is that then access to the generator house is made easy. The top of the generator house having a hourglass shape can be flat, so that it forms a platform above water where personnel can enter the generator house to access the interior of the generator house.

[0029] A slimmer neck section can extend from the generator house in the direction of the wind turbine. The neck section can cover at least a part of the wind turbine shaft as a sleeve.

[0030] The neck section can have a diameter that is less than half the maximum diameter of the bulbs.

[0031] The floating unit is arranged to float in water so that the water surface intersects the floating unit at the neck section.

[0032] An advantage of having the water surface intersecting at the neck section is that since the neck section is slimmer than the bulbs of the hourglass shaped generator house the volume of the floating unit in the splash zone is smaller. Hence, the floating unit is less affected by waves and swells and there will be less movement due to this (less heave for instance).

[0033] The floating unit can be anchored to the seabed with a mooring. The mooring can be connected to the generator house.

[0034] In another aspect the invention relates to a floating installation that comprises three or more floating units.

[0035] The floating installation can further comprise a plurality of waist struts connecting the floating units together. The waist struts can in at least one end be connected to the waist of the generator house.

[0036] The advantage of connecting the struts to the slim waist is that they are connected close to the center of gravity and the center of volume of the generator house. Thus, the construction is stiffer.

[0037] The floating installation can further comprise a plurality of bottom struts connecting the floating units together. The bottom struts can in at least one end be connect to the rod below the water turbine or the stabilizing weight.

[0038] That the bottom struts are connected to the rod below the water turbine means that it is connected to the rod at a point between the distal end and the water turbine and the stabilizing weight.

[0039] The floating installation can further comprise a plurality of top struts to connect the floating units together. The top struts can in at least one end be connect to the neck section.

[0040] The floating installation can further comprise one or more fish cages arranged in between the three or more floating units. An advantage of integrating fish cages on the floating installation is that existing infrastructure and support structures can be used.

[0041] Description of the drawings

[0042] Fig. 1 shows an embodiment of a floating unit for energy harvesting having a vertical axis wind turbine on top, an hourglass shaped generator house below the wind turbine and a water turbine below the generator house.

[0043] Fig. 2 shows a part of the embodiment of the floating unit from Fig. 1 . In this drawing the generator house is cut open so that the interior of the generator house and the interior of the neck above the generator house is visible.

[0044] Fig. 3 shows an embodiment of a floating installation floating in a body of water. The floating installation comprises a plurality of the floating units from fig. 1 and fig. 2.

[0045] Fig. 4 shows the same embodiment of the floating installation as in Fig. 3 from another angle.

[0046] Fig. 5 shows the floating installation, in this embodiment a fish farm with fish cages is integrated with the floating installation from Fig. 3 and 4.

[0047] Table 1 Description of preferred embodiments of the invention

[0048] In the following embodiments of the invention will be described with reference to the drawings (Fig. 1- 4).

[0049] In Fig. 1 a floating unit 10 for energy harvesting is shown. The floating unit 10 comprises a vertical axis wind turbine 20 and a vertical axis water turbine 30. The wind turbine drives a first generator 21 arranged inside a generator house 40. The water turbine 30 drives a second generator 32 also arranged inside the generator house 40.

[0050] The generator house 40 forms a hull that is watertight and provides buoyancy to the floating unit 10. The hull further comprises a slimmer neck section 42 extending up from the generator house 40. The neck section 42 surrounds a vertical wind turbine shaft 22 that couples the wind turbine 20 to the first generator 21. Wind turbine shaft bearings 23 can be arranged inside the neck section 42.

[0051] The generator house 40 can be equipped with hatches, ladders and walkways 45 for personnel to access the generators 21 , 32 and other affiliated systems inside the generator house 40.

[0052] Ballast tanks and a ballast system can be arranged in the generator house 40 so that ballast water can be pumped in and out to adjust how deep the floating unit 10 floats and to tune the stability. The ballast tanks are not displayed in the figures.

[0053] The water turbine 30 is arranged to be turned by current in the water such as current resulting from the tide. The water turbine 30 comprises turbine blades 33 arranged on a elongated hollow shaft 31. Through the center of the hollow shaft is a rod 34. The rod 34 is suspended from the generator house 40 in a proximal end and extends to below the water turbine 30 where a stabilizing weight 35 is hanging from the distal end of the rod 34. The rod 34 with the stabilizing weight 35 is arranged to provide stability to the floating unit 10 in a similar way as the keel of a sailboat. In addition, it helps preventing the water current from bending the water turbine 30 from its intended vertical orientation.

[0054] In Fig. 2 shows the interior of the generator house 40. The generator house 40 is shaped as an hourglass having a narrow / slim waist 41 and a first 43 and a second 44 bulb arranged above and below the narrow waist 41. The generators 21 , 32 are situated in the bulbs 43, 44 which is more spacious. The rod 34 passes straight through the center of the second generator 32 and is anchored in a internal rod anchor 46.

[0055] Inside the neck section 42 the wind turbine shaft bearings 23 is visible and water turbine shaft bearings 36 is visible in a slimmer bottom section 47 protruding down from the hourglass shaped generator house 40.

[0056] The generator house 40, the neck section 42 and the bottom section 47 together forms a watertight hull for the floating unit 10.

[0057] In Fig 3 shows a floating installation 100 comprising a plurality of floating units 10. The floating units 10 are connected with struts 110, 120, 130 into a floating installation 100 or platform. The floating units 10 can be connected with waist struts 110 connecting the floating units 10 at the waist 41 of the generator houses 40. Further top struts 120 connecting the floating units 10 at the neck section 42 and bottom struts 130 connecting the floating units 10 at their rods 34 just above the stabilizing weight 35 or at the stabilizing weight 35. Preferably, the floating units 10 are held together by at least two types of struts (waist 110 / top 120 / bottom 130).

[0058] This floating installation 100 works as a platform for accessing each floating unit 10 and comprises common infrastructure for all the floating units 10. As seen in Fig. 4 the floating installation 100 comprises a offshore substation 140 where the power cables from all the generators 21 , 32 are gathered and the power is transformed and exported via a common export cable 150 to shore.

[0059] As seen in Fig. 5 fish cages 50 for breeding fish is arranged in the spaces between the floating units 10. The bottom 130, top 120 and waist struts 110 can be used for suspending the nets of the fish cages 50. Such a fish farm on board the floating installation 100 can use existing structures and infrastructure. Personnel deployed on the floating installation 100 can take care of both power production and fish farming.

Claims

Claims1. A floating unit (10) for energy harvesting, comprising: a vertical axis wind turbine (20), arranged to drive a first generator (21) via a wind turbine shaft (22), a water turbine (30) comprising a vertical hollow shaft (31) having turbine blades (33), the water turbine (30) is arranged to be powered by a water current and arranged to drive a second generator (32), a generator house (40) enclosing the first (21) and the second generator (32), the generator house (40) is arranged between the wind turbine (20) and the water turbine (30), a rod (34) that is suspended from the generator house (40) and passes through the center of the hollow shaft (31), and a stabilizing weight (35) arranged at the distal end of the rod (34).

2. The floating unit according to claim 1 , wherein the generator house (40) is shaped as a hourglass having a narrow waist (42), wherein the generator house (40) is arranged with its longitudinal axes parallel to the longitudinal axis of the vertical axis wind turbine (20).

3. The floating unit according to claim 2, wherein a slimmer neck section (42) extends from the generator house (40) in the direction of the wind turbine (20), and wherein the neck section (41) covers at least a part of the wind turbine shaft (22) as a sleeve.

4. The floating unit according to claim 2 or 3, wherein the floating unit (10) is arranged to float so that the water surface (1) reaches to the narrow waist section (41) when it is submerged in water.

5. The floating unit according to claim 3, wherein the floating unit (10) is arranged to float in water (3) so that the water surface (1) intersects the floating unit (10) at the neck section (42).

6. The floating unit according to any of the preceding claims, wherein the floating unit (10) is anchored to the seabed (2) with a mooring (48) and wherein the mooring (48) is connected to the generator house (40).

7. A floating installation (100) for energy harvesting, wherein the floating installation (100) comprises three or more floating units (10) according to claims 1-6.

8. The floating installation (100) according to claim 7 when claim 7 is dependent on any of the claims 2-6, wherein the floating installation (100) further comprises a plurality of waist struts (110) connecting the floating units (10) together and wherein the waist struts (110) in at least one end is connected to the waist (41) of the generator house (40).

9. The floating installation (100) according to claim 7 or 8, wherein the floating installation (100) further comprises a plurality of bottom struts (130) connecting the floating units (10) together and wherein the bottom struts (130) in at least one end is connected to the rod below the water turbine (30) or the stabilizing weight (35) of the generator house (40).

10. The floating installation (100) according to any of the claims 7-9 when claim 7 is dependent on any of the claims 4-6, wherein the floating installation (100) further comprises a plurality of top struts (120) connecting the floating units (10) together and wherein the top struts (120) in at least one end are connected to the neck section (42).

11. The floating installation (100) according to any of the claims 7-10, wherein the floating installation (100) further comprises one or more fish cages (50) arranged in between the three or more floating units (10).

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