DE20111441U1 - Buoyancy bodies for floating and semi-floating wind farms - Google Patents

Description

2. Description:

Flexibly suspended buoyancy bodies stabilize platforms for semi-floating or fully floating wind turbines.

Offshore wind turbines on foundations on the seabed have been built at sea for about 10 years (Denmark) and the experience has been expanded with new turbines in England and Sweden.

The floating variant of this technology was introduced by Hydrotop and protected in the utility model no. 299 08 897.9, registered on August 26, 1999 (IPC: F03 D 11/04) . Reference is made to the utility model . This utility model was developed on this basis.

The floating variants make it possible to use deeper waters further away from the coast for wind power. Ultimately, there is hope that this will solve the earth's energy problems in an affordable way because there is no potential limit. Around 3/4 of the earth's surface is covered by sea, many areas of which have excellent conditions for using wind energy. This variant can be used both for electricity production in places closer to the coast and for hydrogen-based methanol production in marine areas far from the coast.

But it could also speed up the entry into maritime wind power use. Many offshore wind farm developers are waiting for reliable wind turbines with 4 to 5 megawatts of power for their projects in order to be able to operate these wind farms economically. _

With floating wind farms, only three wind turbines per platform would be needed to achieve a power limit of 4.5 to 6 MW. Turbines of this size are already being manufactured in series. Floating wind farms could enable the _large -scale entry into maritime wind power use to take place earlier. &igr; X i,j

The technical solution proposed in the above-mentioned utility model has a crucial problem which makes its realisation difficult.

Regardless of whether the frame structure of the platform - connected to the central support mast - is built below or above the water level, the buoyancy body is always below the wave area. This means that the buoyancy force must always be precisely adapted to the respective situation using a technical device. This means that in the event of strong wind pressure or other weights, e.g. freezing rain or snowfall, the entire platform would sink without any control intervention. On the other hand, if the buoyancy were too strong, the buoyancy bodies would protrude above the water level and be exposed to the forces of the waves. Due to the large surface area of the buoyancy bodies, catastrophic damage would naturally be unavoidable in the event of strong wave forces.

The solution now lies in reducing the buoyancy forces below the water level and supplementing them with buoy-like, flexible buoyancy bodies on the water surface. This applies both to platforms whose frame construction lies above the wave area (Figure 1) and to platforms whose frame construction lies below the wave area (Figure 2). In principle, both variants are possible, but it must be ensured that the frame construction of the platform never comes directly into the wave area.

In calm weather, these buoys would be 1/3 in the water and 2/3 (= buoyancy reserve) above the water level. In contrast to the buoyancy body below the water level, the buoy-shaped buoyancy body hangs above the supporting frame structure of the platform, connected to a flexible steel cable, chain or rod and automatically ensures - without any technical regulation - a dynamically stable position of the entire platform, regardless of the size of the platform.

The flexible suspension allows the buoy to move backwards or to the side when faced with heavy waves, so that these enormous forces are dynamically cushioned. Only in this way can viable and, above all, survivable platforms for floating wind turbines be built.

However, if only a single buoy were responsible for the buoyancy, the entire platform would be pulled upwards by a wave crest and sink downwards by a wave trough. There would be a constant up and down movement. This would place additional strain on all components. Therefore, the entire required buoyancy power must be distributed across many buoy-shaped buoyancy bodies so that the total buoyancy power is always approximately the same.

While on a semi-floating platform the majority of the buoyancy bodies are attached behind the wind turbines, on a fully floating platform these buoyancy bodies would be attached evenly on both sides. (Figure 3)

Additional use of the buoy-shaped buoyancy body on a floating platform: On a fully floating platform - used at depths of 80 m or more - the tension of the holding rope is dynamically increased by this buoyancy body so that no sudden loads can occur on the holding rope and the platform. Like a dog leash, the platform is gently pulled towards the central pivot point and in the event of high wind and wave pressures, dynamic evasion is always possible without the need for technical equipment. (Figure 3)

The buoys could be built in a half-shell shape, transported by ship to save space and assembled on site. They should be equipped with a moisture monitor and should be accessible for inspection and repair purposes. A lockable and tight hatch on the top of the buoy can make this possible. A central internal strut should increase the stability of the buoyancy body. (Figure 5)

3. Summary:

The addition of the buoy-shaped buoyancy bodies to the Hydrotop concept is easy to understand, but also ingenious and indispensable. The production of these buoyancy bodies can also be commissioned without any problem from any shipbuilding company and the prices for series production should be low. They save the platform from having to use complex and expensive control technology. The gentle dynamics of the buoyancy forces due to the large number of such buoys protect all components of this floating wind farm, which also increases the economic efficiency of the entire system. However, these buoyancy bodies are indispensable in extreme wind conditions for the survivability of the platform. The survivability of the platform in all conceivable situations is the prerequisite for its development, construction and large-scale use in all ice-free seas in the world.

Claims (2)

1. A semi-floating or fully floating platform for the use of wind energy at sea, which is characterized by - that its flexible buoyancy body (buoy-shaped) keeps the entire platform - both in the above-water and underwater version - dynamically in the correct position - in relation to sea level; the flexibility is achieved by a non-rigid connection (chain, steel cable or similar) between the frame construction of the platform and the buoyancy body, - that this buoyancy body keeps the holding rope between the "anchor" and the platform dynamically taut when the platform is fully floating. 2. These buoyancy bodies are characterized by
Humidity detectors so that their functionality can be continuously checked
Watertight lockable hatch for inspection and repair purposes
Sandwich construction for space-saving transport and quick assembly
Stabilization band in the center of the buoy
Flow-optimized shape - drop shape - to reduce wave energies ( Fig. 4)