The present invention relates to a method of operating a hydrocarbon production system, with reduced carbon dioxide (CO2) emission. The invention further extends to a corresponding hydrocarbon production system, to a combination comprising said hydrocarbon production system, and to a method of retrofitting an existing hydrocarbon production system for conformity with said hydrocarbon production system.

Hydrocarbon production systems, and in particular offshore hydrocarbon production facilities, often comprise one or more gas turbine engines (GTE) for local power generation at the production system. Typically, a portion of the hydrocarbon gases produced may be combusted in the GTE to produce power for the operation of the production system. The exhaust gases produced from the combustion, comprising a significant portion of carbon dioxide, are vented to the atmosphere.

The significant detrimental impacts that carbon dioxide emission has on the environment are notoriously well-known. There is therefore a general desire, where possible, to reduce carbon dioxide emission to the environment and, as time goes on, this desire only grows. The regulations surrounding operation of hydrocarbon production systems reflects this growing desire, with mandates on the reduction of the ‘carbon footprint’ for such systems being introduced by the various regulatory bodies.

In accordance with a first aspect of the invention, there is provided a method of operating a hydrocarbon production system, the hydrocarbon production system comprising a gas turbine engine configured to provide power for the hydrocarbon production system, the method comprising: splitting produced hydrocarbon gas to form blue hydrogen and carbon dioxide; combusting the blue hydrogen in the gas turbine engine to provide power for the hydrocarbon production system; capturing the carbon dioxide formed from splitting the hydrocarbon gas; and storing the captured carbon dioxide in a set of storage pipes at the hydrocarbon production system.

The invention of the first aspect is advantageous since, as compared to typical methods of operation of hydrocarbon production systems as outlined above, carbon dioxide emission is significantly reduced. This is because blue hydrogen formed from hydrocarbon gas is combusted in the gas turbine engine rather than the hydrocarbon gas itself. The resultant by-products of the combustion of hydrogen in the gas turbine engine is solely water; no carbon dioxide is produced and vented to the atmosphere as is the case where hydrocarbon gas is combusted. The carbon dioxide that is produced from splitting the hydrocarbon gas to form the blue hydrogen is captured and stored, and is hence not vented to the atmosphere. As such, emission of carbon dioxide to the atmosphere (and the detrimental environmental impacts associated therewith) through operation of the hydrocarbon production system in accordance with the first aspect is reduced and may in fact be totally avoided (i.e. the method of the first aspect of the invention can result in operation of the hydrocarbon production system with net-zero carbon dioxide emissions).

‘Blue hydrogen’, as is known in the art, is the term given to hydrogen produced from the process of splitting hydrocarbon gas.

The hydrocarbon production system may be or comprise an offshore hydrocarbon production facility. The hydrocarbon production facility may be a hydrocarbon production platform, e.g. an unmanned hydrocarbon production platform.

The step of splitting produced hydrocarbon gas may comprise splitting hydrocarbon gas that has been produced at the hydrocarbon production (i.e. the same hydrocarbon production system at which the step of splitting takes place).

The hydrocarbon production system may be a land based hydrocarbon production system.

It will be understood by the skilled person that a hydrocarbon production system is a system that is specifically configured for the production and/or processing of hydrocarbons (e.g. oil, natural gas, etc.). As such, the hydrocarbon production system will comprise a degree of production equipment and/or a degree of processing equipment configured for processing or part-processing (i.e. configured to process or part-process) the produced hydrocarbons.

It is possible that the step of splitting of hydrocarbon gas may result in additional by-products to carbon dioxide being formed, e.g. carbon monoxide. The exact makeup of the resultant by-products formed is determined by the nature and steps of the splitting process undertaken.

The hydrocarbon production system may comprise suitable carbon dioxide capturing means to carry out the step of capturing the carbon dioxide formed from splitting the produced hydrocarbon gas. The step of storing the captured carbon dioxide in a set of storage pipes at the hydrocarbon production system may comprise intermittently/temporarily storing the carbon dioxide in the set of storage pipes. That is to say, the storage pipes may only be/ provided for intermittent/temporary storage - i.e. a ‘buffer’ storage.

The method may comprise transporting the carbon dioxide away from the hydrocarbon production system for permanent storage. This may be achieved by suitable transportation means (optional examples of which are described further below). In that way, the hydrocarbon production system permits the captured carbon dioxide to be handled in the short term, with the storage pipes acting as a ‘buffer’ or temporary storage whilst avoiding emission to the environment. Subsequent to this, optionally where a sufficient volume of carbon dioxide has been stored in the storage pipes to warrant its transport, transportation from the production system and to a more permanent storage enables the carbon dioxide to be dealt with permanently. Thus, the method of the first aspect provides a more long lived and sustainable solution to the carbon dioxide produced at the hydrocarbon production system as compared to the prior art methods discussed above.

Prior to the optional step of transporting, the method may comprise offloading the carbon dioxide from the hydrocarbon production system to a transportation means, e.g. a transportation ship or vessel. The step of offloading may comprise use of existing and known offloading technology.

Transporting the stored carbon dioxide away from the hydrocarbon production system for permanent storage may comprise transporting the carbon dioxide to a land-based storage facility. Optionally, where the hydrocarbon production system is offshore, transporting the stored carbon dioxide away from the hydrocarbon production system may comprise use of a vessel and/or a tanker.

The permanent storage may be a man-made/artificial storage facility - i.e. not a naturally occurring storage facility.

The permanent storage may comprise a geological formation. Thus, the carbon dioxide may be considered to be geologically sequestered once permanently stored.

The permanent storage may comprise mineral storage of the carbon dioxide. The mineral storage may be realised through reaction of the carbon dioxide that has been captured and transported with metal oxides to form carbonates (i.e. minerals). The method may comprise storing some or all of the blue hydrogen formed from the step of splitting produced hydrocarbon gas. This may comprise use of suitable storage means, e.g. use of storage pipes. These storage pipes may correspond to those used to store the carbon dioxide, which are described in further optional detail below. The step of storing may comprise temporarily storing the blue hydrogen prior to its supply to the gas turbine engine for its combustion therein. As such, the storage means may be considered a ‘buffer’ or intermediate storage.

The gas turbine engine may be used to produce electrical power for the hydrocarbon production system as a result of the combustion of blue hydrogen. This may entail use of an electrical generator connected to the gas turbine engine. The gas turbine engine may additionally and/or alternatively may be configured to directly power components of the hydrocarbon production system, e.g. to provide a direct drive to a compressor of the hydrocarbon production system.

The hydrocarbon production system may comprise a plurality of gas turbine engines. Each gas turbine engine may be configured to provide power for the hydrocarbon production system. The method may comprise: combusting the blue hydrogen in some or all of the plurality of gas turbine engines to provide power for the hydrocarbon production system.

The method may comprise the step of liquefying the captured carbon dioxide. This liquefying step may occur as a part of (i.e. comprised within) the capturing step of the method or may occur as a sequential step occurring after the carbon dioxide has been captured. The step of storing the captured carbon dioxide in the storage pipes at the hydrocarbon production system may comprise storing the carbon dioxide as a liquid in the storage pipes. The optional step of transporting the stored carbon dioxide away from the hydrocarbon production system for permanent storage may comprise transporting the carbon dioxide as a liquid.

Optionally, liquefying the captured carbon dioxide comprises liquefying the captured carbon dioxide at ambient temperature conditions. The method may comprise storing carbon dioxide in the storage pipes at the hydrocarbon production system and/or transporting the captured carbon dioxide as a liquid at ambient temperature conditions. The skilled person will appreciate that liquefying carbon dioxide at ambient temperature conditions, and equally storing and transporting carbon dioxide as a liquid at ambient temperature conditions requires the carbon dioxide to be pressurised at pressures far above ambient pressure conditions with the exact pressure conditions being determined by the specific ambient temperature at which the carbon dioxide is stored.

Conventionally, liquefaction of carbon dioxide, and transportation and storage of carbon dioxide as a liquid is carried out at ambient pressure conditions and hence, as will be understood by the skilled person, at very low temperature conditions that are significantly below ambient temperature conditions. In the context of the invention however, in particular in the optional context of offshore hydrocarbon production systems, whilst possible it is less advantageous to liquefy, store and/or transport carbon dioxide at temperature conditions significantly below ambient temperature conditions. This is because there is significant complexity and expenditure, both operational and capital, associated with the equipment, personnel and processes required to produce and maintain carbon dioxide as a liquid at such temperature conditions and at ambient pressure conditions. In an offshore scenario, limited space also means that it may not be viable to provide the necessary infrastructure to produce liquefied carbon dioxide at ambient pressure conditions.

Thus, it is thought to be particularly advantageous (though optional) in the context of the invention of the first aspect to liquefy carbon dioxide at ambient temperature conditions, and further optionally to store and/or transport the carbon dioxide as a liquid at ambient temperature conditions. As noted above, this requires the carbon dioxide to be pressurised at pressure conditions well above ambient conditions; however, the pressurisation required is associated with significantly reduced complexity and expenditure, both operational and capital, in terms of the equipment, personnel and processes involved and hence is particularly suited to offshore scenarios.

Ambient temperature conditions may be any temperature between 0 - 25 °C. As such, the pressure required in order to liquefy the carbon dioxide may be between 34 barg - 45 barg, with the exact pressure required being determined by the ambient temperature selected.

The set of storage pipes at the hydrocarbon production system may comprise a first set of storage pipes. Transporting the stored carbon dioxide away from the hydrocarbon production system for permanent storage may comprise transporting the carbon dioxide within a second set of storage pipes away from the hydrocarbon production system for permanent storage. The term ‘storage pipe’ refers to a storage container formed from a length of pipe, which has been closed at each end, optionally by a hemispherical cap or dome that has, for example, been welded to the end of the pipe. Accordingly, the storage pipes are highly elongate, typically having a length-to-diameter ratio of at least 20.

The use of storage pipes as compared to, e.g., conventional tank storage (i.e. vessel storage) as the basis for storage at the hydrocarbon production system and/or transportation is advantageous since it is associated with a significantly lower capital and operational expenditure, particularly in the optional context of transporting carbon dioxide at elevated pressures and ambient temperature conditions as discussed above and in further detail below. In the context of transporting, a plurality of storage pipes also avoids issues of sloshing of the carbon dioxide that can otherwise cause instabilities in scenarios where more conventional storage tanks are used.

Typical ‘tank’ type storage solutions require thick steel walled tanks. These tanks are expensive to provide (given the large amount of material typically required), and are also expensive to transport given their weight (again, given the large amount of material required). The requisite wall thickness (and hence weight of the tank) also limits the size of the tank that can be used, meaning that the volume of carbon dioxide stored therein is limited.

In contrast, pipe storage is relatively inexpensive to provide because standard, ‘off-the-shelf’ pipes may be used to manufacture them. Moreover, for a given volume of storage, pipe storage can have a comparatively smaller wall thickness. Thus, a given volume of carbon dioxide can be stored using a comparatively lower total weight of storage tank material using pipe storage and can be achieved at a lower capital expenditure. Thus, pipe storage is a more viable solution.

The pipe used in each of the first and/or second sets of storage pipes may have a nominal diameter of between 40-60 inches (1 ,0m - 1 ,5m). Preferably, the pipe may have a nominal size of 42 inches (1.1m) or 56 inches (1 ,4m), or may have any nominal size in the range of 42 inches (1.1m) to 56 inches (1.4m).

A vessel having a nominal diameter greater than about 56-60 inches (1.4 m -1.5m) would typically be considered by the skilled person as a conventional tank (or pressure vessel) that is distinct from a pipe. This consideration is also true in the context of the current application, whereby any vessel having a nominal diameter of greater than about 56-60 inches (1 ,4m -1 ,5m) would not be considered as a pipe.

The pipe used may be an X42, X46, X52, X56, X60, X65, X70 or X80 pipe in accordance with the API SPEC 5L specification.

As noted above, the storage pipes are highly elongate. Accordingly, each storage pipe of the first and/or second sets may have a length of between 10 m to 30 m, for example 12 m, 24 m or 26 m.

The storage pipes of the first and/or second sets may be formed from rolled pipes with, optionally, a single longitudinal seam. Such pipes are commonly available as ‘off-the-shelf’ type components and are typically inexpensive.

The storage pipes of the first and/or second sets may be configured for storing (i.e. configured to store) carbon dioxide at an elevated pressure, for example liquefied carbon dioxide at ambient temperature conditions. The storage pipes may be configured to store the carbon dioxide at between 34 barg - 45 barg. The exact pressurised conditions that the storage pipes are configured to store the carbon dioxide at may be selected dependent on the ambient temperature of the carbon dioxide (optionally as a liquid) to be stored therein, the tolerances of the storage pipe and/or the tolerance of the equipment used for loading and unloading the carbon dioxide into the storage pipes.

It is in fact seen to be particularly beneficial, but optional, to store liquefied carbon dioxide at ambient temperature conditions in the (first) set of storage pipes at the hydrocarbon production system. Similarly, it is seen to be particularly beneficial, but optional, to transport liquefied carbon dioxide at ambient temperature conditions within a second set of storage pipes away from the hydrocarbon production system, for permanent storage. This is because the use of storage pipes offers a cheap, simple and technically non-challenging means for handling liquid carbon dioxide at ambient temperature conditions that is superior to other storage solutions.

The first and/or second sets of storage pipes may be vertically arranged. That is, the primary axis of each storage pipe may be vertical. Alternatively, the first and/or second set of storage pipes may be horizontally arranged.

The step of capturing carbon dioxide may comprise use of pressure swing adsorption (PSA), absorption technologies, membranes, cryogenic processes and various combinations thereof. In one example, the step of capturing carbon dioxide may comprise capturing the carbon dioxide in an absorption liquid, optionally in an absorber/contactor in the form of, e.g., a column. The absorption liquid may be an amine solution.

After capturing the carbon dioxide in the absorption liquid, the step of capturing carbon dioxide may comprise stripping/regenerating/desorbing the absorption liquid to remove the carbon dioxide therefrom. The stripping/regenerating/desorbing may be carried out in a stripper/regenerator/desorber in the form of, e.g., a column.

After stripping/regenerating/desorbing, the step of capturing carbon dioxide may comprise compressing the carbon dioxide and/or condensation drying of the carbon dioxide. Collectively or individually, these steps may comprise the optional step of liquefying the carbon dioxide as discussed above.

After stripping/regenerating/desorbing, the method may comprise reusing the absorption liquid for capturing further carbon dioxide formed from the splitting of the produced hydrocarbon gas.

The step of splitting the produced hydrocarbon gas may be based on steam reforming, partial oxidation, auto-thermal reforming or any other technology known to those skilled in the art that can produce hydrogen from hydrocarbon gas. Thus, the step of splitting the produced hydrocarbon gas may be carried out using means capable of splitting via any one of these techniques.

In one example, the step of splitting the produced hydrocarbon gas comprises steam reforming the produced hydrocarbon gas within, for example, a steam reformer.

The step of splitting the produced hydrocarbon gas may take place on a single, modular unit of the hydrocarbon production system. The step of capturing carbon dioxide, the step of storing the carbon dioxide in the storage pipes at the hydrocarbon production system and/or the optional step of liquefying the captured carbon dioxide may take place on a (the) single, modular unit of the hydrocarbon production system. This modular unit may be termed a hydrogen and carbon capture and storage unit where the steps of stripping the carbon dioxide, capturing the carbon dioxide and storing the carbon dioxide at the hydrocarbon production system take place thereon.

The single modular unit may be separate from the remainder of the hydrocarbon production system. For instance, this unit may be a separate facility from the portion of the hydrocarbon production system where the step of combusting produced hydrocarbon gas in the gas turbine engine and/or where hydrocarbons are produced. In an offshore scenario, the separate modular unit may be a separate floating unit situated adjacent, e.g., a production platform that constitutes the remainder of the hydrocarbon production system.

Having a separate, modular unit is advantageous since it can be easily installed/retrofitted in combination with an already existing hydrocarbon production system in order that the invention of the first aspect can be implemented without significant downtime in production at the already existent hydrocarbon production system. This also means that little to no modification is required to the already existing hydrocarbon production system, for the invention to be employed other than maybe a modification of the gas turbine engine to allow it to combust hydrogen rather than hydrocarbon gas or a replacement of the gas turbine engine for one that is configured to combust hydrocarbon gas. Such modification/replacement may not be necessary however.

The method of the first aspect may be employed at a brownfield or a greenfield production facility.

In a second aspect of the invention, there is provided a hydrocarbon production system, the hydrocarbon production system comprising: a gas turbine engine configured to provide power for the hydrocarbon production system; means (i.e. apparatus) for splitting produced hydrocarbon gas to form blue hydrogen and carbon dioxide; means (i.e. apparatus) for capturing carbon dioxide formed from the means for splitting produced hydrocarbon gas; and a set of storage pipes for storing the captured carbon dioxide; wherein the gas turbine engine is configured to combust blue hydrogen in order to provide power for the hydrocarbon production system.

The method of the first aspect of the invention, including any optional features thereof, may be a method of operating the hydrocarbon production system of the second aspect of the invention.

The hydrocarbon production system of the second aspect may be in accordance with the hydrocarbon production system discussed above in relation to the first aspect of the invention and may comprise any optional features thereof.

In a third aspect there is provided a combination comprising the hydrocarbon production system of the second aspect, optionally inclusive of any optional feature thereof, and a transportation vessel configured for transporting (i.e. configured to transport) the stored carbon dioxide away from the hydrocarbon production system for permanent storage.

The combination of the third aspect of the invention may be configured to carry out the method of the first aspect of the invention, optionally inclusive of any optional features thereof.

The transportation vessel of the third aspect of the invention may be in accordance with the vessel described above in connection with the first aspect of the invention.

In a fourth aspect of the invention, there is provided a method of retrofitting an existing hydrocarbon production system, the existing hydrocarbon production system comprising a gas turbine engine configured to provide power for the hydrocarbon production system, the method comprises: installing means (i.e. apparatus) for splitting hydrocarbon gas to form blue hydrogen and carbon dioxide; installing means (i.e. apparatus) for capturing carbon dioxide formed from the means for splitting produced hydrocarbon gas; installing a set of storage pipes for storing the captured carbon dioxide; and one of: modifying the gas turbine such that it is configured to combust blue hydrogen to provide power for the hydrocarbon production system; or replacing the gas turbine engine with another gas turbine engine that is configured to combust blue hydrogen.

The hydrocarbon production system resulting from the method of the fourth aspect may be a hydrocarbon production system in accordance with the second aspect, optionally inclusive of any optional feature thereof.

In accordance with a fifth aspect of the invention, there is provided a method of operating a hydrocarbon production system, the hydrocarbon production system comprising a power source configured to provide power for the hydrocarbon production system, the method comprising: splitting produced hydrocarbon gas to form blue hydrogen and carbon dioxide; fuelling the power source with the blue hydrogen to provide power for the hydrocarbon production system; capturing the carbon dioxide formed from splitting the hydrocarbon gas; and storing the captured carbon dioxide in a set of storage pipes at the hydrocarbon production system.

The power source of the fifth aspect of the invention may be an internal combustion engine, such as a gas turbine engine as discussed above in connection with the first aspect of the invention or a gas engine. Alternatively, the power source may be a fuel cell. A hydrocarbon production system correspondent to the method of the fifth aspect of the invention is also provided in a sixth aspect of the invention.

The fifth or sixth aspects of the invention may benefit from any of the compatible, optional features discussed above in connection with the first to fourth aspects of the invention.

Certain embodiments of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

Figure 1 depicts a hydrocarbon production system and a transportation vessel; and

Figure 2 is a part-cutaway profile view and cutaway plan view of the transportation vessel of Figure 1.

Figure 1 shows an offshore hydrocarbon production system 1 comprising an offshore hydrocarbon production facility in the form of an offshore production platform 3 and a further facility in the form of a hydrogen and carbon capture and storage (CCS) unit 9 situated proximate to but separate from the offshore production platform 3. The hydrocarbon production system 1 , via the hydrogen and CCS unit 9, is connected to a transportation vessel (tanker) 23 via a conduit 22.

The hydrocarbon production system 1 is configured for producing hydrocarbons via suitable production equipment (not shown) situated at the production platform 3. Also situated at the platform 3 is a gas turbine engine 5. The gas turbine engine 5 is configured to provide electrical power for the functioning of at least the production platform 3 and optionally the entire hydrocarbon production system 1 by powering an electrical generator 6.

A conduit 7 on the production platform 3 is configured to receive a portion of the hydrocarbon gas produced thereat. The conduit 7 passes from the production platform 3 to the hydrogen and CCS unit 9 so as to permit passage of the produced hydrocarbon gas from the production platform 3 to the hydrogen and CCS unit 9

On the hydrogen and CCS unit 9 there is situated a steam reformer 11. The steam reformer 11 is connected to the conduit 7 and is thus configured to receive the produced hydrocarbon gas therefrom. The steam reformer 11 is connected to a heat source 11a and a water source 11b which, in combination with the hydrocarbon gas received from conduit 7, provide the requisite conditions and products for steam reformation of the produced hydrocarbon gas.

The steam reformer 11 has a first output connected to carbon dioxide capture unit 13. The carbon dioxide capture unit 13 is configured to isolate and capture carbon dioxide produced from the steam reformer 11 and to liquefy the carbon dioxide at ambient temperature conditions. A condensation drying unit 17 is connected to an output of the carbon dioxide capture unit 13. The condensation drying unit 17 is configured to receive compressed liquid carbon dioxide therefrom. The condensation drying unit 17 is configured to condense any carbon dioxide that may have vaporised after output from the carbon dioxide capture unit 13 such that the liquid state of the carbon dioxide is maintained.

An output of the condensation drying unit 17 is connected to a storage means 19 on the hydrogen and CCS unit 9. The storage means 19 comprises a plurality of storage pipes 19a. The storage pipes 19a are configured to store the liquid carbon dioxide received from the condensation drying unit 17 at ambient temperature conditions and suitable pressurised conditions to maintain the carbon dioxide as a liquid. Whilst in Figure 1 only two such storage pipes 19a are shown, this is schematic and in practice there may be several tens, hundreds or even thousands of such storage pipes 19a at the hydrogen and CCS unit 9 depending on the volume of carbon dioxide that is required to be stored.

A first end of a conduit 22 is attached to an output of the storage means 19 and a second end of the conduit 22 is attachable to an inlet of a tanker 23 as shown in Figure 1. The conduit permits liquid carbon dioxide from the storage pipes 19a to be transferred to the storage pipes 23a on the tanker 23 for subsequent transportation. Again, in Figure 1 only six storage pipes 23a are shown on the tanker 23, however this is schematic and in practice there may be several tens, hundreds or even thousands of such storage pipes 23a. An example of this is shown in Figure 2. Figure 2 shows an embodiment of the tanker 23 comprising thousands of such storage pipes 23a positioned in several cargo holds 25 on the tanker 23.

The steam reformer 11 also has a second output connected to conduit 15. The conduit 15 extends from the hydrogen and CCS unit 9 to the adjacent production platform 3 where it connects to an inlet of the gas turbine engine 5. The second output is configured to output blue hydrogen produced in the steam reformer 11 to the conduit 15. The conduit 15 then feeds the blue hydrogen to the inlet of the gas turbine engine 5 for combustion.

A hydrogen storage means 16 is also provided on the hydrogen and CCS unit 9. This storage means is made up of storage pipes correspondent to the storage pipes 19a and the storage pipes 23a discussed above but configured for storage of hydrogen rather than carbon dioxide. The hydrogen storage means 16 is connected to a bypass of the conduit 15 and serves as a buffer storage for the blue hydrogen produced from the steam reformer 11. Thus, the storage means 16 can act to store blue hydrogen in excess of the demands of the operation of the gas turbine engine 5 and can serve to supply the gas turbine engine 5 with hydrogen when supply from the steam reformer 11 might be reduced.

In use, hydrocarbons are produced at the production platform 3 of the hydrocarbon production system 1 via its production equipment. A portion of the hydrocarbons produced comprise a gas product and at least a portion of this gas product is passed through conduit 7 to the steam reformer 11 on the hydrogen and CCS unit 9.

In the steam reformer 11, the hydrocarbon gases are split through reaction with steam created therein from the water and heat that are input via inputs 11a, 11b. The splitting reaction creates blue hydrogen and carbon dioxide.

The blue hydrogen created is passed out of the steam reformer 11 via the conduit 15 and is transferred to an inlet of the gas turbine engine 5 on the production platform 3. The gas turbine engine 5 combusts the blue hydrogen and, as a result, drives the generator 6 which in turn provides electric power to the hydrocarbon production platform 3. The combustion of the blue hydrogen in the gas turbine engine 5 results only in the creation of water as a by-product.

The carbon dioxide produced at the steam reformer 11 is sent to the carbon dioxide capture unit 13. Herein the carbon dioxide is isolated, captured and liquefied at atmospheric temperature conditions before being passed to the condensation drying unit 17. In the condensation drying unit 17 any vaporised carbon dioxide is returned to a liquid state. The liquefied carbon dioxide is then passed for storage within the storage pipes 19a of the storage means.

Intermittently, once there is sufficient liquid carbon dioxide stored in the storage pipes 19a to warrant it, a tanker 23 having storage pipes 23a thereon will travel to the site of the hydrocarbon production system 1 , specifically the site of the hydrogen and CCS unit 9. The second end of the conduit 22 is then attached to an inlet of the tanker 23. At this stage, liquid, ambient temperature carbon dioxide is offloaded from the storage pipes 19a to the tanker 23 to be stored in the storage pipes 23a thereon via the conduit 22.

During the offloading process, part of the liquefied carbon dioxide may vaporise. Any vaporised carbon dioxide received at the tanker 23 is passed back to the condensation drying unit 17 via suitable conduits, where it is condensed and subsequently returned to the storage pipes 19a for later loading onto a vessel 23.

After the storage pipes 23a have been filled on the tanker 23, the tanker 23 is disconnected from the conduit 22. The tanker 23 then transports the liquid carbon dioxide away from the hydrocarbon production system for permanent storage.

Only blue hydrogen is combusted in the gas turbine engine 5 in order to provide power for the production platform 3. No carbon-containing product passes for combustion at the gas turbine engine 5. As such, the emission of carbon dioxide to the atmosphere from the gas turbine engine 5 is avoided. Instead, the carbon from the produced hydrocarbon is captured and transported for permanent storage. As such, its detrimental emissions to the atmosphere are avoided.