Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03B—MACHINES OR ENGINES FOR LIQUIDS
  • F03B17/00—Other machines or engines
  • F03B17/06—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head"
  • F03B17/062—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head" with rotation axis substantially at right angle to flow direction
  • F03B17/063—Other machines or engines using liquid flow with predominantly kinetic energy conversion, e.g. of swinging-flap type, "run-of-river", "ultra-low head" with rotation axis substantially at right angle to flow direction the flow engaging parts having no movement relative to the rotor during its rotation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
  • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
  • F05B2240/00—Components
  • F05B2240/40—Use of a multiplicity of similar components
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient

Definitions

• This application concerns a system for generating energy from water currents.
• the invention is particularly suited for use in tidal currents, river currents or ocean currents, and particularly where there is a limited cross section that water moves through, for instance rivers or narrow passages or sounds.
• the use of the tidal energy is one of the most environmentally friendly and predictable of all known sources of energy.
• Plants for collecting flowing current energy has seen limited use, because the costs will become to prominent as very large plants are required to collect even fairly modest amounts of energy.
• the size of the plants has done that they represent environmentally unfavourable changes and at the same time have been obstructing boat traffic etc.
• US 3 922 012 shows a patent where a multitude of vertical turbines are placed on a frame that it is to be lower down to be placed on the sea bed.
• the frame has floating elements enabling the plant to be buoyant and to be towed to a suitable location.
• the floating elements are then been ballasted, such that the plant sinks and becomes located on the seabed.
• Patent US 3 912 937 describes a system for the production of electrical energy from ocean currents based on a two-part turbine blade construction. The plant is completely placed underwater and comprises a horizontally placed turbine.
• Patent US 5440 176 is based on a movable turbine, that is, it can be adjusted up and down in relation to the platform/frame depending of the operating conditions.
• the present invention concerns a plant that can cover a large cross section of a flowing mass of water, but nevertheless with components at a more manageable size, where the maintenance is simplified, and where the components or the entire plant more easily can be raised to the surface for maintenance and repair.
• a plant for the production of electric energy from ocean or river currents that comprises turbines with blades, shafts and side units, generators for the production of electric current; frame assembly equipped with buoyant vessels, assembled from one or several sub frames, where the plant as a whole is placed below the surface of the water.
• the shafts of the turbines are oriented substantially perpendicular to the direction of the velocity of the water, and the turbine shafts are supported in the frame assembly.
• the plant has positive buoyancy adjusted by the buoyant vessel and a backstay system is anchored below surface of the water, such that the plant is kept below the surface of the water by the backstay system.
• the blades are shaped as wings such that the turbines are rotating in the same direction regardless of the direction of the flow of the water.
• Figure 1 shows the plant according to the invention as it will be seen from the sea bed looking towards the system in the direction of the flowing current.
• Figure 2 shows the plant seen from 2-2 on figure 1.
• Figure 3 shows the plant seen from 3-3 on figure 2.
• FIG. 4 and 5 shows turbines in detail.
• Figure 6 shows an elevated view corresponding to figure 2 where the localization of the system is shown.
• the turbines (A), comprises wing shaped blades (G), formed such that the turbines (A) will rotate in the same direction, regardless of the direction of the water flow.
• the blades (G) are supported on each side.
• Generators (not shown) are connected to the shaft of the turbines (A), and will produce electric energy, that it is transferred through a cable (not shown).
• the generator is protected against ingress of water by means of a water resistant enclosure and possibly an overpressure in the enclosure.
• the turbines (A) are supported in frames (C) that comprise a number of vertical and horizontal frames or sub frames that are assembled as modules.
• the modules are assembled to create a plane with several turbines. This plane can thereby be adjusted to a desired cross section of current in a passage or a river. It is also possible to build the most critical components in such a way that they are reasonably easy to substitute in a running phase. This is particularly relevant in terms of exchanging components having an expected high frequency of repair and maintenance.
• the framework design gives in general a favourable distribution of the design forces, particularly those that acts on the turbine bearings.
• the buoyant vessels (B) are also installed on top of each end, and in the middle, to allow easy adjustment of the buoyancy of the plant.
• Figure 4 and 5 shows a cross section of the impeller (A) where the shape of the wing shaped blades (G) is better shown.
• the shape ensures that the impellers rotate in the same direction regardless of the direction of the water flow.
• the blades (G) can furthermore be made with adjustable pitch to better utilize the energy of the current.
• the blades (G) are secured to circular plates at each end to form the turbines (A).
• the shafts of the turbines are connected at the centre of each of these circular plates.
• the shafts of the turbines can be secured on each circular end plate to avoid that the shafts extend through the turbine. This will improve the flow conditions in the turbine.
• the backstay, or anchoring comprises tight anchor lines (E) keeps the plant under water and acts against the buoyancy.
• the anchoring is chosen from a request of the smallest possible play of the plant.
• Steel ropes or wires of the type "spiral strand" are chosen to achieve a long expected lifespan.
• the backstays (E) should furthermore be treated to avoid corrosion.
• the anchor lines are secured to five submerged winches (not shown) installed on the structure.
• the power to the winches is supplied through hydraulic hoses with quick release couplings placed on top of the plant.
• anchor lines (E) for reducing the load on the anchor lines (E) and to reduce the effect in the event of breaking a line.
• the anchor lines (E) are secured to the five vertical frames (C) in the carrying assembly.
• Two anchor lines (E) are secured to each end of the plant.
• These anchor or backstay lines (E) are loaded with vertical and horizontal forces both in the length axis and transversally of the plant.
• the backstays are secured to the bottom or lower part of the frames. All the backstays (E) have an angle 45° in relation to the seabed.
• the carrying assembly is designed as a steal frame. It comprises five vertical frames or sub frames with a height of 14 m and a centre distance 16 m interconnected by means of a horizontal frame. Total centre distance between the outer frames is 64 m. Because of the requirement for 10 m sailing height above the plant, the steel frame (C) will be situated 23 m below the water surface, that is, 27 m above the seabed. The distance to the seabed is thereby 20 m.
• the frame (C) comprises 500 mm tubular profiles with 20 mm wall thickness.
• the turbines (A) are arranged in two horizontal levels with four turbines in eacho level and horizontal shaft support. Thereby the centre distance of the turbines (A) becomes 14 m in vertical direction.
• the turbine consists of five blades that spans 12 m unsupported between two end plates with diameter of 12 m.
• the blades are of NACA 0016 profile meaning that the greatest blade thickness is 16% of the length of the blade.
• the length of the blades is set to 3.2 m such thats that the greatest thickness of the impeller blade is 512 mm. Hollow profile blades are chosen to save weight.
• the end plates comprise circular plates with corrugated core to reduce the weight. Total thickness is 120 mm. Total dry weight per turbine is estimated to 64 t. Similarly total buoyancy per turbine is 81 t. Thereby each turbine will have a net buoyancy of 17 1, which is suf-o ficient to carry the weight of the generator and gear system in connection with the turbine.
• the duration curve for the measured flow velocity flats out at ca. 1.75 m/s and it should be inquired if it is profitable to dimension for greater velocities than this.o This gives a turbine effect of 139 kW. The contribution from velocities above 1.75 m/s to an annual production is ca. 10%.
• the plant comprises 8 turbines where each generator shaft is connected to two turbines. This gives a maximum shaft effect of 416 kW per generator.
• the power cables to the surface can be connected in the atmosphere or under water. When coupled in the atmosphere, the cable is led through the enclosure with a water resistant cable gland or passage, which is a standard product on the market, and is connected to the generator terminals inside the enclosure. The enclosure must then be coupled to the generator before it is installed under water. This requires then that the generator with gear and enclosure is installed and secured to the carrying assembly after the carrying assembly has been installed and anchored or moored. In the invent of a breakdown of the generator, gear or cable, the cable will be pulled up along with the generator/gear module and is disconnected onboard a vessel.
• the cable is sufficiently long to, or the cable has sufficient play, so that the module can be elevated.
• an electric underwater coupler or connector is used. One part of the connector is then secured on the outside of the enclosure. The other part is then secured to the cable and is connected to the enclosure when the ca- ble is laid.
• the generator/gear module can then be mounted on the carrying assembly onshore and be installed as a part of the total assembly. In the event of breakdown, the cable can be released from the generator/gear module under water and the generator/gear module or the cable can be hoisted up for repair.
• the electric under water connectors are expensive units, but this method can prove to reduce installation and maintenance costs more than the added cost for the electric system as a whole.
• the poles will typically have a dimension between 30" to 60", and are installed in 10-15 m deep boreholes.
• the plant is positioned on the place of installation with the short side towards the direction of the current flow, and five anchor lines on one side are secured by means of a smaller craft. Then, forerunners are secured to the five anchor lines on the other side to five under water winches that are installed on the structure. Power supply for the winches comes from hydraulic hoses with quick release couplings on the upper part of the carrying structure.
• the method requires somewhat longer anchor lines than those that are anticipated for the construction of the carrying structure. Furthermore the use of fibre ropes with a protective layer (against fouling and sand intrusion) is recommended to ease the installation work. Any increase of costs with this change, is in this connection assumed to be of a smaller magnitude.
• the tidal plant will be submerged 10 meters below the ocean surface and will therefore not be visible. Where the cable is to be landed on shore, houses for frequency converters and transformers will be installed and will be visible, as before the installation. The plant will reduce the tidal current with approximately 20% in the area the plant will be placed. The water mills will rotate the same direction regardless of the direction of the water flow.
• a tidal power plant will have two opposite effects on the tidal current: A reduction of the velocity due to the increased resistance of the flow given by the plant, and an increase of the velocity because the plant blocks some of the cross section and chokes or throttles the current. If the water mills are distributed in the passage as windmills are distributed in large parks, the mills will only increase the resistance and reduce the current. But if the watermills are placed tightly together in the one and same cross-section, the velocity of the current in this cross section will increase even though it is reduced elsewhere in the passage. Thereby the watermills can drain more energy when they are placed in the same cross section and block the passage than they would if they were distributed.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Other Liquid Machine Or Engine Such As Wave Power Use (AREA)

Priority Applications (5)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (5)

Cited By (10)

Families Citing this family (3)

Citations (4)

• 2000
  • 2000-06-02 AU AU2000251152A patent/AU2000251152A1/en not_active Abandoned
  • 2000-06-02 EP EP00935736A patent/EP1287258A1/en not_active Withdrawn
  • 2000-06-02 CN CN00819726A patent/CN1454290A/zh active Pending
  • 2000-06-02 CA CA002413850A patent/CA2413850A1/en not_active Abandoned
  • 2000-06-02 WO PCT/NO2000/000187 patent/WO2001092720A1/en not_active Application Discontinuation

Patent Citations (4)

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