NO20230250A1 - Low-Carbon ammonia offshore floating, production, storage and loading device, system and method - Google Patents

Description

Title: Low-Carbon ammonia offshore floating, production, storage and loading device, system and method.

Technical field:

[001] The present invention relates broadly to an offshore system for producing ammonia with carbon capture and storage (CCS) from natural gas.

Background:

[002] With the 2030 Climate Target Plan, the EU Commission proposes to raise the EU's ambition on reducing greenhouse gas emissions to at least 55% below 1990 levels by 2030. To achieve this, there has been an expansion of interest in low or zero emission power production, as well as carbon capture and storage. In the field of liquefaction of natural gas, there has also been a growing interest in using ammonia (NH3) as a carrier to transport zero or low emission hydrogen (H2).

[003] To meet the ambition on reducing greenhouse gas emissions, several different systems and methods for transporting energy has been considered. As an energy carrier, ammonia is becoming more popular as it has three times the energy density that of compressed hydrogen, creating potential as a carbon-free energy carrier. Ammonia (NH3) consists of nitrogen and hydrogen and is commonly used in the fertiliser industry. Whilst ammonia has a well-established supply chain, the “blue ammonia” and “green ammonia” market is only just starting to be explored.

[004] In the field of ammonia, “blue ammonia” is commonly referred to as is a low-carbon method of producing ammonia, typically using steam methane reformation (SMR). Hydrogen is first derived from methane, where carbon dioxide is a by-product that can be captured and stored. The hydrogen reacts with nitrogen in a secondary process to produce ammonia, most used presently is the Harber-Bosch method. “Green ammonia” is typically produced through electrolysis of water, powered by renewable energy. Except for the production footprint of the renewable energy platforms and the use of heat in the Harber-Bosch process, hydrogen can be produced with close to zero carbon dioxide in the electrolysis process. The main steps for producing blue ammonia are essentially the same as for producing conventional fossil fuel-based ammonia, the difference being that most of the carbon stemming from the natural gas feedstock is captured, providing a possibility for underground sequestration. To produce blue ammonia, several different processes are known, such as the one disclosed in WO2022228839A1. Furthermore, in the field of ammonia, low-carbon ammonia is considered to be ammonia made from hydrogen derived from natural gas feedstocks and nitrogen, with at least parts of the carbon dioxide (CO2) produced being captured and stored.

[005] During exploration and extraction of hydrocarbons, there is a large quantity of proven natural gas discoveries that today are left unused. This gas is referred to as stranded gas, and is generally known as a natural gas field that has been discovered, but remains unusable for either physical or economic reasons. Stranded gas can also be the last part of gas in a gas field that is not extracted. A volume of gas can be economically stranded because it is remote from a market for natural gas, making construction of a pipeline prohibitively expensive. Gases are expensive to transport over long distances, especially on small scale. Thus, stranded gas is considered to not have any value as it is not economically feasible or physically possible to extract the gas. A large potential value is thus left untouched in countless offshore wells all over the world. It is therefore a need for a system that can take advantage of such gas resources.

[006] Document US 2022388855 A1 discloses a containerized system for salt production and carbon capture method by employing the transportable ammonia producer. Specifically, water, air, and electrical power are input into the transportable ammonia producer of the present invention to generate oxygen and ammonia. Then, the produced ammonia, water, carbon dioxide, and electrical power can be input into a carbon dioxide capturing system. The solution produces hydrogen gas from a water source and does not utilize stranded gas or surplus natural gas resources for the production. Furthermore, the solution requires a separate power source, such as such as wind, solar, tidal, geothermal, or hydropower.

[007] Document US 2022388842 A1 discloses a method for converting a flare gas to an end product, wherein the end product comprises a compound selected from the group consisting of methanol, ethanol, mixed alcohols, ammonia, dimethyl-ether, and F-T liquids. This method has the downside of only deal with flare gas, and not volumes of stranded gas in a well.

[008] There exist some solutions that produce energy offshore, like the solution disclosed in US 2022246318 A1, which discloses an offshore energy generation system that delivers electricity, ammonia (NH3) and freshwater to onshore consumers through piping. However, the system disclosed in US 2022246318 A1 relies on nuclear fission, nuclear fusion or Hydrogen (H2) fuel cell to produce the electricity and ammonia, and expensive tubing to transfer said production onshore. However, said system does not utilize the resources available in stranded gas.

[009] Furthermore, document WO 2019204857 A1 discloses an offshore energy generation system for the delivery of electricity and/or hydrogen onshore, comprising an offshore platform secured to the seafloor, a separate liquid ammonia storage vessel associated with the offshore platform, said storage vessel adapted to receive liquid ammonia from an ammonia carrier in the form of a ship, an electricity generating module mounted to the offshore platform and fuelled by ammonia from the liquid ammonia storage vessel for generating electricity to be supplied onshore via an electrical cable. The disclosed system has the downsides that it requires an external supply of ammonia and a separate storage vessel in addition to be located relatively close and stationary to any onshore facility.

[010] There exists systems and methods that can produce ammonia at offshore facilities, such as the system disclosed in document AU 2014101274 A4, which discloses an ammonia synthesis offshore. The method comprises the steps of generating electricity on-shore from a facility powered by renewable energy and transfer the electricity via high voltage cable to an offshore platform. The platform comprises a desalination plant, an electrolysis plant, a nitrogen production plant and a Haber Bosch ammonia synthesis plant to produce ammonia. The disclosed system has the downsides that it requires an external supply of electricity and a separate storage vessel in addition to be located relatively close and stationary to any onshore facility.

[011] Multiple floating solutions for either producing ammonia or generate electricity from ammonia have been suggested, however, none of these have the unique characteristics included in independent claims of the present invention.

[012] It is therefore an aim of the present invention to overcome the drawbacks of the known prior art. The current onshore blue hydrogen or ammonia production incorporates piped natural gas, where fugitive methane, transport costs and fluctuating market rates of the gas challenges compared to our invention.

Summary of the invention:

[012] The invention is set forth and characterized in the main claims, while the dependent claims describe other characteristics of the invention.

Description of the drawings:

[013] The various aspects of embodiments herein, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

Fig. 1 illustrates an FPSO unit

Fig. 2 illustrates a front view of an FPSO unit, an associated offshore filed and a transport vessel.

Detailed description of the drawings.

[014] Embodiments herein will now be described more fully with reference to the accompanying drawings, in which example embodiments are shown. However, this application should not be construed as limited to the embodiments set forth herein. Disclosed features of example embodiments may be combined as readily understood by one of ordinary skill in the art to which this application belongs. Like numbers refer to like elements throughout.

[015] Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

[016] Figure 1 illustrates an example of a floating production, storage and offloading (FPSO) unit 1. The unit can be any type of floating unit, such as a vessel, floater, barge or the like with a displacement hull. In the illustration, the FPSO unit 1 comprises means for receiving a natural gas stream and producing ammonia. Said means may be gas receiving means 2, such as risers, pipes and the like, adapted to capture and transport a natural gas stream from at least one source of natural gas 13. In the illustrated example, the source of natural gas 13 is a stranded gas filed. However, the gas receiving means 2 may receive natural gas from other connected sources, such as flair gas from another production vessel (not shown) or an associated gas source. The natural gas stream is transported, through receiving means 2, on board the FPSO unit 1 wherein it is received by gas pre-treatment and separation means 3. The gas pre-treatment and separation means 3 is adapted to remove non-methane gasses from the natural gas stream and provide at least a methane gas stream and a non-methane gas stream.

[017] The illustrated FPSO unit 1 comprises further power generating means 4 adapted to receive at least a portion of the methane gas stream and/or at least a portion of the nonmethane gas stream and produce electric power from said gas stream(s). Preferably, the power generating means 4 comprises at least one gas turbine fuelled by a portion of the nonmethane gas stream and/or a portion of the methane gas stream. The power generating means 4 may be electronically connected to different systems and modules on the FPSO unit 1, such that the power generating means 4 can provide all the electrical power necessary for the FPSO unit 1 to operate.

[018] The illustrated FPSO unit 1 comprises further gas treatment and separation means 31, adapted to receive the methane stream, or at least a portion of the methane stream to produce a hydrogen- (H2) and a carbon dioxide- (CO2) stream. The process of producing hydrogen (H2) and a carbon dioxide (CO2) from methane (CH4) is known in the art. Typically this can be done, with steam methane reforming (SMR). Thus, the invention disclosed herein can comprise as treatment and separation means 31 comprising a steam methane reforming (SMR) module adapted to react the methane gas (CH4) stream with steam (H2O) and oxygen (O2), coupled with the subsequent removal of water and carbon dioxide (CO2) to produce a hydrogen stream (H2), adding a nitrogen stream (N2). The nitrogen stream may be generated from air.

[019] To produce low-carbon ammonia, the FPSO unit 1 comprises ammonia production means 5 in fluid communication, directly or indirectly, with the gas treatment and separation means 31 i, adapted to convert the hydrogen stream (H2) and a nitrogen stream (N2), received from the gas treatment and separation means 31, into an ammonia stream (NH3). There exists several different processes to convert hydrogen (H2) and a nitrogen (N2) into ammonia stream (NH3), such as the Haber–Bosch process. In an embodiment of the invention, the ammonia production means 5 comprises a Haber–Bosch module performing the Haber–Bosch process, wherein the nitrogen stream (H2) reacts with the hydrogen stream (H2) to produce an ammonia stream (NH3).

[020] To further add to the reduction of carbon dioxide (CO2) and to increase the efficiency of the invention, the ammonia production means 5 can be in heat communication, such as through a heat exchanger, with the gas treatment and separation means 31. The production of ammonia (NH3), for instance through the Haber-Bosch module is an exothermic reaction wherein heat is released or produced. An exothermic reaction is a chemical reaction in which less energy is needed to break bonds in the reactants than is released when new bonds form in the products. During an exothermic reaction, energy is constantly given off, often in the form of heat.

[021] The production of hydrogen (H2) and carbon dioxide (CO2) from methane (CH4), for instance through a steam methane reforming (SMR) module, is an endothermic reaction which requires the input of heat, preferably through steam. Thus, with the ammonia production means 5 in heat communication, such as through a heat exchanger, with the gas treatment and separation means 31, the heat from the ammonia production means 5 is used in the gas treatment and separation means 31. Thus, the heat from the ammonia production means 5 can be used to generate steam for the gas treatment and separation means 31.

[022] The ammonia (NH3) can be stored in an accompanying ammonia storage 6, adapted to store ammonia (NH3) received from the ammonia stream (NH3). The storage 6 comprises at least one enclosed tank.

[023] To unload the produced and stored ammonia (NH3), the FPSO unit may comprise ammonia transfer means 7 in fluid communication, directly or indirectly, with the storage means 6, to transport the ammonia from the storage means to a separate transport vessel 8. The transfer means 7 can be any suitable unloading means, such as a bow or stern mounted unloading, or loading system comprising tubes, pipes and/or pumps. Said transfer means 7 mas can also be used to transfer cargo, such as carbon dioxide (CO2) from transport vessel 8 to the FSPSO unit 1. In an embodiment, the invention can be utilized to received carbon dioxide (CO2) captured on a remote facility, such as onshore, and inject said received carbon dioxide (CO2) into permanent storage means together with any carbon dioxide (CO2) captured on the FPSO unit 1 during the production of ammonia (NH3).

[024] To be able to produce low-carbon ammonia, carbon dioxide (CO2) can be captured at least from the gas treatment and separation means 31 with carbon capture means (9) situated on board the FPSO unit 1 and in communication with the gas treatment and separation means 31. The captured or received carbon dioxide (CO2) can be stored in carbon dioxide (CO2) storage means 11, adapted to receive and store CO2 on board the FPSO unit 1. The carbon dioxide (CO2) storage means 11 may comprise at least one tank.

[025] To further add to the reduction of carbon dioxide (CO2) and to increase the efficiency of the invention, the FPSO unit 1 may further comprises an additional carbon capture means 91 associated with the power generating means 4, and being adapted to capture carbon from flue gas from the power generating means 4.

[026] Figure 2 illustrates a system in accordance with an embodiment of the invention, wherein an FPSO unit 1, as previously disclosed herein is located near by an offshore stranded gas well 13. By nearby it should be understood that it is directly or indirectly in fluid communication with the stranded gas well with natural gas through the receiving means 2 and adapted to receive natural gas. The FPSO unit 1 may be moored through a mooring arrangement 14 by the gas well 13. To extract the natural gas from the gas well 13, a wellhead 15 associated with the natural gas and the receiving means 2, may be situated on the seafloor 16. Furthermore, the system is illustrated with a sub-surface reservoir 12 adapted for injecting carbon dioxide (CO2) either captured by the capture means on the FPSO unit 1 or received from an extern source, such as the transfer vessel 8. The sub subsurface reservoir 12 can be a depleted carbon source, such as an old offshore well, or a suitable sub-surface formation.

[027] Associated with the sub-surface reservoir 12 are carbon injection means 10 comprising a sub-sea injection wellhead adapted to inject carbon dioxide (CO2) into the subsurface reservoir 12. In the illustration, the carbon injection means 10 are in fluid communication with the CO2 storage means 11 on board the FPSO unit 1 through carbon dioxide transfer means 17, such as such as risers, pipes and the like. Any CO2 stored in the CO2 storage means 11, can then be pumped, through an associated pump, or transferred, through the associated transfer means 17, from the CO2 storage means 11 on board the FPSO unit 1 to the carbon injection means 10, associated with the sub-surface reservoir 12, and injected into the sub-surface reservoir 12 for permanent storage.

[028] Figure 2 further illustrates a transfer vessel 8. Preferably, the transfer vessel is a dual cargo vessel with storage tanks adapted to receive carbon dioxide (CO2) from another location (not illustrated). Thus, carbon dioxide (CO2) captured from other processes, such as an industrial facility on land, can be shipped to the FPSO unit 1, whereby it is transferred to the FPSO unit 1 and subsequently transferred to the sub-surface reservoir 12, and injected into the sub-surface reservoir 12 for permanent storage. The invention, can thereby be employed to store carbon dioxide (CO2) captured by processes produced on the FPSO unit 1, as well as carbon dioxide (CO2) released or produced elsewhere. The dual cargo vessel 8 can either have different tanks for storage CO2 and NH3, or the dual cargo vessel 8 can have cleaning means for preparing the same cargo tanks to hold CO2 and NH3 at separate times.

[029] The transfer vessel 8 is further adapted to receive ammonia (NH3), produced on the FPSO unit 1 and stored in the one or more associated ammonia storage tank(s) 6, via transfer means 7. The transfer means 7 can be extended from the FPSO unit 1 and connected to cargo tanks of the transfer vessel 8 to unload the ammonia (NH3). The transfer vessel 8 can then ship the ammonia (NH3) to a purposeful destination. The transfer means 7 can also be adapted to transport carbon dioxide (CO2) from the transfer vessel 8 to the carbon dioxide (CO2) storage on the FPSO unit 1.

Figure 2 illustrates an embodiment of the invention wherein it is provided a system for production, storage and offloading of low-carbon ammonia and capture and storage of carbon. The system comprises the FPSO unit 1, associated with and in fluid communication with, at least one source of natural gas 12, and at least one offshore well for carbon injection and storage comprising at least one sub-sea injection wellhead. The FPSO unit 1 can further be associated with and in fluid communication with, the transport vessel 8, wherein the transport vessel 8 is a dual cargo tanker, adapted to hold and transport ammonia and carbon dioxide (CO2).

[030] The invention further relates to a method for production, storage and offloading of ammonia and capture and storage of carbon dioxide, the method comprises the steps of providing a FPSO unit (1) as previously disclosed and capture a natural gas stream from at the natural gas 12 via gas receiving means 2. The subsequently remove non-methane gasses from the natural gas stream and provide at least a methane gas stream and a nonmethane gas stream, by a gas pre-treatment and separation means 3, and to receive at least a portion of the methane gas stream and/or at least a portion of the non-methane gas stream and produce electric power from said gas stream(s) by the power generating means 4. The power is adapted to power the unit 1 and/or different modules associated with the unit 1. Further, receive the methane stream produce a hydrogen (H2) and a carbon dioxide (CO2) stream via gas treatment and separation means 31, and convert the hydrogen stream (H2) and a nitrogen stream (N2) to an ammonia stream (NH3) by ammonia production means 5. Subsequently the ammonia is stored after being received from the ammonia stream (NH3) in an ammonia storage (6), and further transported the ammonia from the storage means to a transport vessel 8 via ammonia transfer means 7. Carbon dioxide (CO2) released from the gas treatment and separation means 31 is then captured by carbon capture means 9 and stored on board the FPSO unit 1 in storage means.

[031] The method may further comprises the step of injecting the carbon dioxide (CO2,) received from the storage means 11, into at least one offshore well 12 via at least one subsea injection wellhead 10 in association with both the FPSO unit 1 and the offshore well 12, wherein the storage means 11 of the FPSO unit 1 are in fluid connection with the carbon injection means 10 and adapted to inject the captured carbon dioxide (CO2). The method may further comprises the step of to receiving carbon dioxide (CO2) from an on-shore facility and transfer said carbon dioxide (CO2), by the dual cargo ship 8, to the FPSO unit 1, and transfer said carbon dioxide (CO2) to the storage means 11, for subsequently injecting the transferred CO2 into the offshore well 12 by an injection well head.

[032] Although specific embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents. For instance, it should be understood that all embodiments of the FPSO unit 1 could be used in the disclosed system and method.

Reference numerals:

1 A floating production, storage and offloading (FPSO) unit, such as vessel or a mobile offshore unit.

2 Gas receiving means; tubes, pipes and/or riser from a gas source.

3 Gas pre-treatment and separation means, separator of non-methane gasses from methane gasses.

31 Gas treatment and separation means, module for treatment and separation of gas.

4 Power generating means

5 Ammonia production means

6 Ammonia storage, tank

7 Ammonia transfer means; tubes, pipes and/or pumps.

8 Transport vessel, tanker vessel.

9 Carbon capture means; carbon capture module

10 Carbon injection means; Sub-sea injection wellhead

11 CO2 storage means, tank(s) on floating unit

12 Offshore well, sub sub-surface reservoir, for carbon storage

13 Natural gas source, offshore well or associated gas.

14 Mooring arrangement

15 Wellhead

16 Seafloor

17 Carbon dioxide transfer means

Claims (16)

1. A floating production, storage and offloading (FPSO) unit (1) for production, storage and offloading of ammonia and capture and storage of carbon dioxide, the unit (1) comprising:

- gas receiving means (2) adapted to capture a natural gas stream from at least one source of natural gas (12), and;

- gas pre-treatment and separation means (3) adapted to remove non-methane gasses from the natural gas stream and provide at least a methane gas stream and a non-methane gas stream, and;

- power generating means (4), adapted to receive at least a portion of the methane gas stream and/or at least a portion of the non-methane gas stream and produce electric power from said gas stream(s), wherein the power is used to power the unit (1) and/or different modules associated with the unit (1), and;

- gas treatment and separation means (31), adapted to receive the methane stream and to produce a hydrogen (H2) and a carbon dioxide (CO2) stream, and;

- ammonia production means (5), adapted to convert the hydrogen stream (H2) and a nitrogen stream (N2) to an ammonia stream (NH3),

- an ammonia storage (6), adapted to store ammonia (NH3) received from the ammonia stream (NH3), wherein the storage facility comprises at least one enclosed tank, and;

- ammonia transfer means (7), adapted to transport the ammonia from the storage means to a transport vessel (8),

- carbon capture means (9), adapted to capture carbon dioxide (CO2) from the gas treatment and separation means (31),

- carbon dioxide (CO2) storage means (11), adapted to receive and store CO2 on board the FPSO unit (1).

2. The FPSO unit (1) according to claim 1, wherein the gas treatment and separation means (31) comprises a steam methane reforming (SMR) module, adapted to react the methane gas stream with steam (H2O) and oxygen (O2), coupled with the subsequent removal of water and carbon dioxide (CO2) to produce a hydrogen stream (H2), adding a nitrogen stream (N2) generated from air.

3. The FPSO unit (1) according to any of the previous claims, wherein the ammonia production means (5) comprises a Haber–Bosch module adapted to react the nitrogen stream (H2) with the hydrogen stream (H2) to produce an ammonia stream (NH3).

4. The FPSO unit (1) according to any of the previous claims, wherein the ammonia production means (5) is in heat communication with the gas treatment and separation means (31), whereby heat from the ammonia production means (5) is used to generate steam for the gas treatment and separation means (31).

5. The FPSO unit (1) according to any of the previous claims, wherein the power generating means (4) is at least one gas turbine fuelled by a portion of the non-methane gas stream and/or a portion of the methane gas stream.

6. The FPSO unit (1) according to any of the previous claims, wherein the floating unit (1) further comprises an additional carbon capture means (91) associated with the power generating means (4), and being adapted to capture carbon from flue gas from the power generating means (4).

7. The FPSO unit (1) according to any of the previous claims, wherein the stream of natural gas at least comprises methane.

8. A system for production, storage and offloading of blue ammonia and capture and storage of carbon, the system comprises:

- the FPSO unit (1) according to any one of the claims 1-8,

- at least one source of natural gas (12), and;

- at least one offshore well for carbon injection and storage, and;

- at least one sub-sea injection wellhead (10) in association with both the FPSO unit (1) and the offshore well, wherein the carbon capture means (9) of the FPSO unit (1) are in fluid connection with the carbon injection means (10) and adapted to inject the captured carbon dioxide (CO2) into at least one of offshore well.

9. The system according to claim 8, wherein at least one source of natural gas (12) is a one or more offshore stranded gas wells and/or associated gas.

10. The system according to claim 8 or 9, wherein the system further comprises a transport vessel (8), wherein the transport vessel (8) is a dual cargo tanker, adapted to hold and transport ammonia and carbon dioxide (CO2).

11. The system according to claim 10, wherein the transport vessel (8) is adapted to transfer two loads, a carbon dioxide (CO2) load and an ammonia load, wherein the transport vessel (8) is adapted to be loaded with carbon dioxide (CO2) received from an onshore facility and transport said carbon dioxide (CO2) to the floating unit (1) to inject the transported carbon dioxide (CO2) into the at least one offshore well, and adapted to be loaded with ammonia from the floating unit (1) to transport the ammonia to an onshore facility.

12. The system according to claim 10 or 11, wherein transport vessel (8) is preferably an ammonia-fuelled vessel.

13. The system according to claims 8-12, wherein the carbon injection means (10) comprises a sub-sea injection wellhead (10) in fluid communication with the carbon capture means (9) or a carbon storage tank (11) on the FPSO unit (1), wherein the sub-sea injection wellhead (10) is adapted to inject carbon dioxide (CO2) received from the carbon capture means (9) or carbon storage tank (11) into the offshore well (12).

14. A method for production, storage and offloading of ammonia and capture and storage of carbon dioxide, the method comprises the steps of providing a FPSO unit (1) according to any one of the claims 1-7, and to

a) capture a natural gas stream from at least one source of natural gas (12) via gas receiving means (2), and;

b) remove non-methane gasses from the natural gas stream and provide at least a methane gas stream and a non-methane gas stream, by a gas pre-treatment and separation means (3), and;

c) receive at least a portion of the methane gas stream and/or at least a portion of the non-methane gas stream and produce electric power from said gas stream(s) by power generating means (4), wherein the power is used to power the unit (1) and/or different modules associated with the unit (1), and;

d) receive the methane stream and to produce a hydrogen (H2) and a carbon dioxide (CO2) stream via gas treatment and separation means (31), and;

e) convert the hydrogen stream (H2) and a nitrogen stream (N2) to an ammonia stream (NH3) by ammonia production means (5), and;

f) store ammonia (NH3) received from the ammonia stream (NH3) in ammonia storage (6), and;

g) transport the ammonia from the storage means to a transport vessel (8) via ammonia transfer means (7), and;

h) capture carbon dioxide (CO2) from the gas treatment and separation means (31) by carbon capture means (9),

i) receive and store CO2 from the carbon capture means (9) on board the FPSO unit (1) in carbon dioxide (CO2) storage means (11).

15. The method according to claim 14, wherein the method comprises the further steps of:

f) injecting the carbon dioxide (CO2,) received from the storage means (11), into at least one of offshore well (12) via at least one sub-sea injection wellhead (10) in association with both the FPSO unit (1) and the offshore well (12), wherein the storage means (11) of the FPSO unit (1) are in fluid connection with the carbon injection means (10) and adapted to inject the captured carbon dioxide (CO2).

16. The method according to claim 14 or 15, wherein the method comprises an additional step, either prior to step a) or after step i), to receive CO2 from an on-shore facility and transfer said CO2, by a dual cargo ship 8, to the FPSO unit 1, and transfer said CO2 to the storage means (11).