Integrative system for centralised offshore hydrogen production in conjunction with a floating generation and storage unit

Abstract

The invention relates to a system for generating energy in open water, in which an offshore wind turbine WEA is releasably connected to a marine vehicle FPSO, which comprises a transformer device TR for converting into lower and / or higher electrical voltage, an electrolysis device ES for generating hydrogen H2, and a tank T for storing the hydrogen. The invention advantageously provides for dynamic changes between the operating modes of storage and transmission, redundancy and maintainability.

Description

[0001] Description

[0002] Integrative system for central offshore hydrogen production in conjunction with a floating generation and storage unit

[0003] The invention relates to a system for generating energy by means of a wind turbine in open water and a generation and storage unit floating in the water.

[0004] The invention further relates to a generation and storage unit floating in the water for the conversion, storage and transmission of energy, which is electrically connected to an offshore wind farm for the generation of energy.

[0005] The invention comprises a modular system comprising conventional power transmission (HVAC / HVDC) and hydrogen production, storage, and transport in conjunction with an FPSO (Floating Production and Storage Unit). The offshore substation is electrically connected to a wind turbine (WT) cluster.

[0006] The power grid infrastructure limits the energy generation and feed-in of renewable energies into the grid. To maintain grid stability, power grid operators continue to switch off dynamically controllable energy sources such as wind and solar. Energy storage, for example using hydrogen as an energy carrier, is becoming increasingly important, and infrastructure problems are driving the ramp-up of hydrogen production. The focus is on large-scale offshore projects of approximately 500 MW and upwards. The volatile load spectrum of the wind turbines requires a dynamic ramp-up of the electrolysis units. This requirement, together with a high technical readiness level, can currently be met primarily using PEM stacks (proton exchange membrane). These have a larger footprint (transmission capacity) than, for example, alkaline electrolyzers.Coupled with large transmission capacities, initial studies have shown that the electrolysis units cannot be integrated into existing platform designs. Furthermore, platforms with a hydrogen transmission capacity of more than 900 MW are not feasible due to their weight and the required area of ​​more than 600 MW based on the current state of electrolyzer development.

[0007] The invention is based on the problem of providing a system for generating energy in the power class > 500 MW by means of a wind turbine in open water with flexible adaptation to different transmission and consumption capacities.

[0008] The problem is solved by a system having the features of claim 1.

[0009] In addition to a hybrid transmission, the present invention features integration by means of a detachable and rotatably mounted slip ring connection (swivel system) with advantages such as storage, maintainability, redundancy, dynamic switching between operating modes, etc.

[0010] The hybrid system provides for the transformation of electrical energy to a higher voltage level for export to the land station and, on the other hand, to a lower voltage level in order to supply the electrolysis unit with energy as required.

[0011] Advantageous further developments of the invention are specified in the subclaims.

[0012] The invention is explained in more detail below as an exemplary embodiment to the extent necessary for understanding, using the figures. These figures show: Fig. 1 shows a basic connection of a wind turbine with a platform and a floating generation and storage unit,

[0013] Fig 2 a basic connection of a wind turbine with a floating generation and storage unit,

[0014] Fig 3 a mooring system mounted on the floating generation and storage unit,

[0015] Fig 4 a keel-integrated solution,

[0016] Fig 5 an external turret mooring system,

[0017] Fig 6 an underwater connection and

[0018] Fig 7 the arrangement of H2 tanks T in the floating generation and storage unit .

[0019] In the figures, like designations refer to like elements.

[0020] The system described below represents a hybrid solution that combines green hydrogen production with electricity transmission. The hybrid system offers the following advantages, among others:

[0021] - Increased availability through two largely independent operating systems

[0022] / Energy ready positioning systems,

[0023] - Overcoming critical electricity transmission network infrastructure problems through energy transport using hydrogen,

[0024] - Dynamic load control of the electricity adapted to the demand (hydrogen driven / electricity driven),

[0025] - Reduction of OPEX through optimized maintenance activities compared to decentralized offshore

[0026] Was ser f f produkt ionskonzept en,

[0027] - Reduction of CAPEX : o Cables : Reduction of the cable cross section , which has a particular impact as the distance from the coast increases .

[0028] The hybrid system provides for the transformation of electrical energy to a higher voltage level for export to the land station and to a lower voltage level in order to supply the electrolysis unit with energy as required.

[0029] Two different approaches are given.

[0030] In variant a) WEA - platform - FPSO according to Fig. 1, the wind farm WEA is electrically connected via a platform PF.

[0031] A detachable connection (VT, DL) allows the FPSO to be decoupled from the offshore substation (PF). This allows the entire FPSO to be brought into port for maintenance work, and the work can be carried out onshore. This eliminates the need for offshore-certified personnel for planned and unplanned maintenance and repair work on the electrolysis system. Therefore, the costs for transporting the crew to the FPSO are completely eliminated. During maintenance work on the electrolysis system, the HV power transmission onshore is not affected.

[0032] The PF substation platform houses all high-voltage electrical equipment, which generally includes the following components:

[0033] - switchgear,

[0034] - Transformer TR,

[0035] - HVDC / AC converter (VSC, English “Voltage Source Converter”),

[0036] - Throttle .

[0037] The electrical system also includes units for cooling, monitoring and control, safety, and communications. The electrical system design primarily relies on conventional equipment, which does not require any fundamental new developments.

[0038] The subsystems of the FPSO include the following units, with extensions / adaptations possible:

[0039] - Electrolysis stacks ES , - Water treatment plant (desalination, demineralization, deionization) ,

[0040] - cooling system,

[0041] - compaction system,

[0042] - buffer T ,

[0043] - Low voltage and auxiliary systems,

[0044] - Tower anchoring VT with rotatably mounted slip ring connection SR .

[0045] The hybrid model, which can be used in a power class of >500 MW, can be switched to different operating modes. Depending on the customer's needs, the operator can distinguish between two approaches:

[0046] • Hydrogen controlled: The electricity generated by the wind turbines WEA / Hub / Cluster initially covers the nominal capacity of the electrolyzer, while the remaining electricity is transmitted to land via the HVDC / AC transmission unit via the HV sea cable.

[0047] In this case, the electrolyzer uses the base load of electricity generation.

[0048] • Power-controlled: The electrolyzer uses only the surplus electricity generated. In this case, meeting electricity demand takes priority, and the electrolyzer covers peak loads.

[0049] Furthermore, the hybrid transmission and the largely independent operation of electricity and hydrogen production means that maintenance work can be carried out without shutting down the entire system. The two different energy transmission options alone provide redundancy for trouble-free operation. Another advantage: individual control of the electrolyzer modules, which reduces the degradation of the stacks and eliminates the need to accept transmission losses. In variant b) WEC - platform - FPSO according to Fig. 2, an offshore platform is completely dispensed with. The WEC cluster is directly connected to the FPSO. The FPSO is equipped with the equipment of an offshore substation and can be designed either as a pure hydrogen production unit or as a hybrid with part hydrogen production and part electricity transmission (UHV).

[0050] Both the electrical system and the electrolysis unit are essentially analogous to variant a) and differ, among other things, in the electrical design of the individual components, the layout, the safety concept, and the automation concept. The basic functionalities are the same.

[0051] The modular system allows for a flexible solution tailored to the customer as well as spatial modification of the FPSO and thus integration into another wind farm of a similar power class with relatively little adaptation effort.

[0052] FPSO integration

[0053] As shown in Fig. 3, the mechanical connection of the FPSO is via a turret mooring system. This has a mooring tower VT, which is mounted on the FPSO and from which the mooring lines VL extend. While the mooring lines VL are connected geostationarily to the seabed GND, the swivel system SR of the turret mooring system allows rotation around the pivot point S. This ensures improved weather-related alignment of the ship's hull with the aim of reducing movement and acceleration on the ship to a minimum. The main purpose of the swivel system is to compensate for ship movements caused by wind, waves and currents, while maintaining continuous fluid transfer and electrical connection.It allows the ship to rotate freely in changing environmental conditions without placing excessive strain on the moorings.

[0054] The detachable mooring system enables complete physical decoupling of the FPSO. Using the SR slip ring connection, the FPSO can be supplied with the energy generated by the wind turbines via flexible / dynamic cables and connected to the hydrogen grid via a flexible piping system (PS). In addition to connecting to the hydrogen grid, it is possible to store the hydrogen in the FPSO's integrated tanks and transport the produced hydrogen to shore via transport vessels.

[0055] Depending on the space requirements on the FPSO and the specific requirements, the system according to the invention can be implemented as a keel-integrated solution, as shown in Fig. 4, an external turret mooring system, as shown in Fig. 5, or an underwater connection, as shown in Fig. 6. The anchoring system and the counter bearing GL can be arranged separately and at a distance from the wind turbine WEA, but also on the platform PF.

[0056] Integrated tank system of the FPSO's

[0057] As an alternative to the pipeline connection, tanks T for storing hydrogen H2 are arranged in the hull of the FPSO as storage capacities (see Fig. 7).

[0058] Compared to the high-voltage transmission (HVDC), the electrolysis stacks (ES) with their auxiliary systems require more space. As the capacity of the electrolysis unit (ES) increases, the space requirement rises significantly. Depending on the required transmission power and the associated share of the available installation space, the electrolysis stacks (ES) can also be integrated into the currently planned volume of the tanks, thus achieving a higher output of hydrogen and also power transmission while maintaining the same size of the FPSO. This allows the dynamic behavior of the FPSO and the resulting accelerations and movements to be optimized.

[0059] The system according to the invention comprises:

[0060] - Modular design for the integration of a hydrogen production unit into a 33 / 66 / 132 kV wind farm,

[0061] - Integration of high-voltage transmission and / or electrolysis units exclusively on an FPSO,

[0062] - Optional use of the tank system T in the hull of the FPSO for the storage of hydrogen H2,

[0063] - Flexible scalability of transmission power without fundamental changes to the layout of the FPSO,

[0064] - Connection of the FPSO by means of a rotatable and quick-release mooring system in conjunction with an energy transfer system for both electricity and fluids.

[0065] The term "fluid" encompasses hydrogen, as well as its derivatives, such as ammonia, liquid organic hydrogen carriers (LOHC), etc. For illustrative purposes, the present invention has been explained in detail using specific embodiments. Elements of the individual embodiments can also be combined with one another. Therefore, the invention is not intended to be limited to individual embodiments, but rather to be limited solely by the appended claims.

[0066] List of reference symbols

[0067] AC - Alternating Current

[0068] CAPEX - capital expenditures

[0069] DC - Direct Current

[0070] ES - electrolysis stack, electrolysis unit

[0071] FPSO - Watercraft, Floating Production and Storage Unit

[0072] GIS - Gas insulated switchgear

[0073] GL - Counter bearing

[0074] GND - bottom of the water body, ground

[0075] H2 - hydrogen

[0076] HV - high voltage

[0077] HVDC - High-voltage direct current converter, high-voltage transmission

[0078] IGBT - Insulated Gate Bipolar Transistor

[0079] LOHC - liquid organic hydrogen carriers

[0080] MV - medium voltage

[0081] Offshore - on water

[0082] OPEX - operating expenditures Onshore - on land

[0083] PF - Platform

[0084] PS - fluid line, flexible hydrogen line, (engl: Piping System)

[0085] S - vertical, vertical axis, pivot point

[0086] SR - slip ring, (English: swivel system)

[0087] T - Tank system in the hull of the FPSO for storing hydrogen

[0088] TR - High-performance transformer

[0089] UHV - ultra high voltage

[0090] VSC - Voltage Source Converter

[0091] VL - Anchoring line

[0092] VT - Turret Mooring System

[0093] W - waters, open waters (offshore)

[0094] WEA - wind turbine, hub, cluster

Claims

Patent claims 1. System for generating energy by means of a wind turbine (WEA) in open water (W), in which a generation and storage unit (FPSO) floating in the water is held rotatably about the vertical axis (S) at the location of the counterbearing by means of a pivot bearing (DL) which interacts with a counterbearing (GL) fastened to the bottom (GND) of the water, the counterbearing (GL) is electrically connected to the wind turbine, the pivot bearing (DL) and the counterbearing (GL) have a coupling mechanism for mutual release but also connection, the pivot bearing (DL) interacts with the counterbearing (GL) via a rotatably mounted slip ring (SR) for transmitting electrical energy and / or a fluid, in particular hydrogen (H2), from and to the generation and storage unit (FPSO).

2. System according to claim 1, characterized in that the rotary bearing (DL) cooperates with the counter bearing (GL) in such a way that a transfer of a fluid from the generation and storage unit (FPSO) into a fluid line (PS) is provided.

3. System according to one of the preceding claims, characterized in that the pivot bearing (DL) interacts with the counter bearing in such a way that a relative movement in the direction of the vertical (S) is provided.

4. System according to one of the preceding claims, characterized in that the pivot bearing (DL) interacts with the counter bearing in such a way that a tilting movement with respect to the vertical (S) is provided.

5. System according to one of the preceding claims, characterized in that the counter bearing (GL) is fastened to the bottom (GND) of the body of water (W) by means of anchoring lines (VL).

6. System according to one of the preceding claims, characterized in that an electrolysis unit (ES) for producing hydrogen (H2) is arranged on the FPSO.

7. System according to claim 6, characterized in that on the generation and storage unit (FPSO) there is a transformation of the high voltage (HV) of the wind turbine (WEA), in particular 66 / 132 kV, into the low voltage, in particular 600-800 V, of the electrolysis unit (ES).

8. System according to one of the preceding claims, characterized in that on the generation and storage unit (FPSO) a transformation of the high voltage (HV) of the wind turbine (WEA), in particular 66 / 132 kV, into the extra-high voltage (UHV), in particular 320 kV / 525 kV, of the connected long-distance transmission is provided.

9. System according to one of the preceding claims, characterized in that the counter bearing (GL) is electrically connected to the wind turbine via a platform (PF).

10. System according to claim 9, characterized in that on the platform (PF) a transformation of the high voltage (HV) of the wind turbine (WEA), in particular 66 / 132 kV, into the extra-high voltage (UHV), in particular 320 kV / 525 kV, of the connected long-distance transmission is provided.

11. System according to one of the preceding claims, characterized in that the generation and storage unit (FPSO) has a tank (T) in the hull for storing generated hydrogen (H2).

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