A method of storing ammonia and an ammonia storage system

Abstract

The present disclosure relates to method of and a system for storing and handling ammonia. The method comprises the steps of: selecting a storage location in a waterbody; providing a tank system, the tank system comprising at least one communication port and one or more tank sections, each of the one or more tank sections having an inner ammonia-receiving volume in fluid communication with the communication port; arranging the tank system in the waterbody; filling ammonia through one of the at least one communication port, wherein the ammonia is stored in a partially condensed state in which vapour and liquid of the ammonia is separated by a liquid-vapour interface; and removing ammonia from the ammonia-receiving volume through the communication port. The steps of filling the inner ammonia-receiving volume and removing the ammonia is performed while the one or more tank sections are submerged in the waterbody.

Description

[0001] A METHOD OF STORING AMMONIA AND AN AMMONIA STORAGE SYSTEM FIELD OF THE INVENTION The present invention relates to a method of storing and handling ammonia. The present invention further relates to an ammonia storage and handling system. BACKGROUND OF THE INVENTION Industrial ammonia is a primary component of the fertilizers necessary to ensure the food productivity which is required to feed the population of the world. In power-to-X systems envisaged to reconvert renewable energy, ammonia is also considered to be an important reconversion target to provide both fertilization as well as ammonia-based fuel solutions. Moreover, ammonia is also used for synthesis of pharmaceutical products. Large quantities of ammonia naturally require storage solutions capable of storing and handling the substance. Conventionally, ammonia is stored in large spherical or cylindrical storage tanks which must fulfil certain requirements. Typically, these storage tanks store ammonia in the vapour phase and must have either very thick walls to sustain a large internal pressure or be cooled down to ensure a reduced internal pressure. Further, since ammonia poses a health hazard and can pose a risk of exploding, ammonia storages require large safety zones, thereby taking up a lot of space which cannot be used for other purposes. These conditions render conventional ammonia storage solutions ineffective and expensive. Hence, there is a demand for improved ammonia storage solutions. SUMMARY OF THE INVENTION On the above background, it is an object of preferred embodiments of the present disclosure to provide ammonia storage solutions which address the deficiencies of conventional storage solutions. In particular, it is an object of some embodiments to provide ammonia storage solutions which do not require cooling or thick walls. Further, it is an object of some embodiments to provide ammonia storage solutions which do not take up space which can otherwise be used for other purposes. In addition, it is an object of some embodiments of the disclosure to provide improved discharge of ammonia. A first aspect of the present disclosure relates to a method of storing and handling ammonia, the method comprising the steps of: selecting a storage location in a waterbody; providing a tank system, the tank system comprising at least one communication port and one or more tank sections, wherein each of the one or more tank sections has an inner ammonia-receiving volume in fluid communication with the at least one communication port; arranging the tank system in the waterbody; filling ammonia through one of the at least one communication port, wherein the ammonia is stored in a partially condensed state in which vapour and liquid of the ammonia is separated by a liquid-vapour interface; and removing ammonia from the ammonia-receiving volume through one of the at least one communication port, wherein the step of filling the inner ammonia-receiving volume and the step of removing the ammonia is performed while the one or more tank sections are submerged in the waterbody. In contrast to typical conventional ammonia storage solutions, the method of storing and handling ammonia according to the present disclosure is directed at storing the ammonia in a tank system arranged in a waterbody, such as in sea water. This can provide a number of advantages. The ocean bed offers a great amount of territory which is readily available for ammonia storage and handling systems. The large safety zones which are typically required with conventional storage solutions are typically less of a concern when utilizing the ammonia storage solutions offered by the present disclosure, since no residency and little infrastructure is located subsea. In turn, placement in a water body also reduces the space constraints to the storage and handling system itself, which does not have to be compact. Instead, according to the present disclose, an ammonia storage and handling system can be implemented as a tank, e.g., of one or more pipes having a cylindrical shape to thereby form a pipe system. In other words, the tank system is a pipe system, wherein the one or more tank sections are one or more pipe sections. Pipe systems have conventionally been used as subsea gas pipelines, but not for storage and handling of ammonia in a waterbody. Hence, conventional pipe systems can easily be adapted for use according to the present disclosure. This offers a cost-efficient alternative to large and specialized conventional storage tanks. It may moreover permit conventional inspection gauges or gadgets for pipelines generally referred to as pigs or scrapers, to perform various maintenance operations. Further, this enables ammonia storage and handling systems according to the present disclosure to be modularized, which in turn simplifies maintenance, installation, expansion, and decommissioning of ammonia storage and handling systems. Moreover, the waterbody provides at least some degree of external pressure and a stable temperature. This reduces the need for thick walls and cooling of the storage system. According to examples of the present disclosure, the ammonia is stored in a partially condensed state, i.e., a state where a part of the ammonia is in the vapour phase and part of the ammonia is in the liquid phase. The ammonia is substantially in thermal equilibrium with the surroundings of the storage system, but typically at a different pressure, depending on a filling level of the ammonia storage and handling system and a waterbody depth at which the tank system is arranged. In addition, placement of an ammonia storage and handling system in a waterbody may allow easier supply of ammonia to a seafaring vessel such as a bulk carrier configured to receive ammonia or a vessel having an ammonia-based engine. Finally, should a leak of ammonia to the surroundings of the ammonia storage and handling system according to the present disclosure occur, such a leak typically poses less of a hazard in comparison with a leak from conventional storage solutions located above water. Leaks should preferably always be avoided, also in a waterbody. However, since ammonia dissolves naturally in water, any immediate hazardous threat to human health can be avoided. Nevertheless, the ammonia storage and handling systems according to the present disclosure are preferably accompanied by, e.g., a monitoring system such that any leaks can quickly be identified and handled. Preferably, the combined volume of the inner ammonia-receiving volume of each of the tank sections is at least 1000 cubic metres, for example at least 5000 cubic metres, such as in a range from 5000 cubic metres to 30000 cubic metres. The tank system is typically arranged in the waterbody at the storage location. According to examples of the present disclosure, the ammonia is filled into the inner ammonia-receiving volume during the step of filling without simultaneously removing ammonia vapour from the inner ammonia-receiving volume. Such filling of the tank system is not possible in some conventional ammonia storage systems. By filling ammonia, preferably ammonia in the form of liquid ammonia, without removing ammonia vapour, the filling is more efficient, and there is no need for cooling and condensation of the removed vapour. Accordingly, the procedure is less complicated and cheaper. According to examples of the present disclosure, the step of filling ammonia into the inner ammonia-receiving volume is performed without simultaneously removing ammonia vapour from the inner ammonia-receiving volume and while condensing ammonia vapour in the inner ammonia-receiving volume. Such filling of the tank system is not possible in some conventional ammonia storage systems. When adding more ammonia, the pressure and temperature in the system will generally tend to increase. By thermal contact, the surrounding waterbody can then ensure that the ammonia is cooled to a temperature substantially similar to the surrounding waterbody, thereby condensing ammonia vapour. By filling ammonia without removing ammonia vapour, the filling is more efficient. According to examples of the present disclosure, the step of filling ammonia into the ammonia-receiving volume is performed while the ammonia which is provided to the ammonia-receiving volume has a temperature which is different from a temperature of the ammonia already present in the ammonia-receiving volume, and wherein the temperature of the ammonia which is provided to the ammonia-receiving volume is reduced or increased by heat exchange with the waterbody. For example, the temperature of the ammonia which is provided to the ammonia-receiving volume can have a temperature which is different from a temperature of the ammonia already present in the ammonia-receiving volume by at least 5 Kelvin, for example at least 10 Kelvin, for example at least 20 Kelvin, for example at least 40 Kelvin, such as at least 60 Kelvin. By allowing a temperature difference, the ammonia can be received directly from any source, or at least with a reduced intermediate temperature regulation. According to examples of the present disclosure, the at least one communication port comprises an inlet port and an outlet port separate from the inlet port, wherein the step of filling the inner ammonia-receiving volume is performed via the inlet port and the step of removing ammonia from the ammonia-receiving volume is performed via the outlet port. According to examples of the present disclosure, the tank system is arranged in the waterbody such that a depth of the waterbody at the inlet port is less than a depth of the waterbody at the outlet port. Generally, placement of a communication port or outlet port at a relatively great depth ensures efficient removal of ammonia since the relevant port primarily communicates with ammonia in liquid phase in contrast to primarily communicating with ammonia in vapour phase. A relatively great depth can be quantified relative to an inlet port or relative to the liquid-vapour interface. According to examples of the present disclosure, the ammonia is filled into the inner ammonia-receiving volume in gas phase and allowed to at least partially condense in the inner ammonia-receiving volume by heat exchange with the waterbody. In a traditional storage system, vapour is cooled and condensed in a traditional cooling system. By allowing the condensation to be based on heat exchange with the waterbody, energy for cooling and condensation in a traditional cooling system can be avoided. According to examples of the present disclosure, the ammonia is filled into the inner ammonia-receiving volume in liquid phase, which provides efficient, fast, filling of the storage. According to examples of the present disclosure, the method comprises a step of storing the ammonia provided in the step of filling the inner ammonia-receiving volume. According to examples of the present disclosure, a pressure in the inner ammonia-receiving volume at the liquid-vapour interface is different from a waterbody pressure, the waterbody pressure being measured in the waterbody in which the tank system is arranged at the same depth of the waterbody as the liquid vapour interface, for example different by a least 0.5 bar, for example different by at least 1.0 bar, for example different by at least 3.0 bar, for example different by at least 10 bar, such as different by at least 50 bar. The provision of a pressure in the ammonia-receiving volume which is different from a waterbody pressure is distinct from some conventional storage solutions. For example, in a storage solution in which a stored substance is separated from the waterbody by a flexible impermeable membrane which is displaced based on a filling level, the pressure within the receiving volume is substantially the same as the pressure in the surrounding waterbody. According to examples of the present disclosure, the ammonia is stored at a storage temperature which is within a temperature threshold of a surrounding waterbody temperature, wherein the storage temperature is measured within the ammonia-receiving volume and the waterbody temperature is measured in the waterbody in which the tank system is arranged within 2 meters of a position at which the storage temperature is measured and at least 0.5 meter away from the tank system, wherein the temperature threshold is at most 10 Kelvin, for example at most 5 Kelvin, such as at most 2 Kelvin. The provision of a storage temperature which is within a small temperature threshold of a temperature of the surroundings is distinct from some conventional storage solutions. For example, in many conventional solutions, the storage tank is cooled such that the storage temperature is not within a small temperature threshold of the surroundings. The temperature within the ammonia-receiving volume may temporarily shift during filling or removal of ammonia. For example, the ammonia provided to the ammonia receiving volume may have a different temperature than the ammonia already present, and during removal, liquid ammonia which is not removed, may boil to reduce the temperature. Hence, the storage temperature is preferably measured during storage and not during filling or removal of ammonia or within a short duration thereafter. For example, the storage temperature is measured at the earliest 1.0 hour after the latest filling of ammonia and at earliest 1.0 hour after the latest removal of ammonia. Alternatively, a longer waiting time may also be used, for example at earliest 3.0 hours after filling / removal, such as at earliest 5.0 hours after filling / removal. According to examples of the present disclosure, one of the at least one communication ports is a bottom communication port, the bottom communication port being arranged below the liquid-vapour interface when liquid ammonia takes up 10 % of volume of the ammonia- receiving volume. According to examples of the present disclosure, during the step of removing the ammonia, the liquid-vapour interface is located above the one of the at least one communication port through which ammonia is removed. Generally, placement of a communication port or outlet port at a relatively great depth ensures efficient removal of ammonia since the relevant port primarily communicates with ammonia in liquid phase in contrast to primarily communicating with ammonia in vapour phase. A relatively great depth can be quantified relative to the liquid-vapour interface. According to examples of the present disclosure, the tank system comprises at least one pump arranged in communication with the bottom communication port, wherein the step of removing ammonia from the ammonia-receiving volume is performed using the at least one pump. The placement of a pump in communication with the bottom communication port ensures efficient removal of ammonia. A pump located above the liquid-vapour interface will typically only be capable of removing ammonia in vapour phase, which will typically not work well, or at least be significantly less efficient. The at least one pump can be one pump or it can be more than one pump, such as at least two pumps or at least three pumps. According to examples of the present disclosure, the tank system is arranged in the waterbody such that a longitudinal extension of the one or more tank sections is different from a horizontal extension, the horizontal extension defined as being parallel with a surface of the waterbody. A non-horizontal extension improves accuracy when determining a relative filling level of ammonia and improves the capability of the system to efficiently remove ammonia from the ammonia-receiving volume. According to examples of the present disclosure, the method comprises the steps of: positioning one or more pressure sensors onto the one or more tanks sections; performing a measurement of an internal ammonia pressure in the inner ammonia-receiving volume of the one or more tank sections using the one or more pressure sensors; and determining a filling level of ammonia based on the ammonia pressure. The ammonia pressure may be determined based on an ammonia pressure measured with one or more pressure sensors. The general principle of determining a filling level of ammonia based on the ammonia pressure according to the present disclosure utilizes the circumstance that ammonia is stored in a partially condensed state in which vapour and liquid is separated by a liquid-vapour interface. The internal ammonia pressure, particularly at a bottom portion of the tank system, is indicative of the vertical location of the liquid-vapour interface, which in turn is indicative of the filling level. Typically, accuracy can be improved by using a several pressure sensors placed on different depths, and by measuring the storage temperature, but these additional elements can also be omitted for the sake of simplicity. According to examples of the present disclosure, at least one of the pressure sensors is positioned at a bottom portion of the tank system, the bottom portion being positioned below the liquid-vapour interface when liquid ammonia takes up 10 % of volume of the ammonia- receiving volume. According to examples of the present disclosure, at least one of the pressure sensors is positioned below the liquid-vapour interface during the step of performing a measurement. According to examples of the present disclosure, the filling level is calculated based on liquid- vapour phase transition pressure. The liquid-vapour phase transition pressure provides the pressure at the liquid-vapour interface. Any surplus pressure measured by a pressure sensor positioned below the liquid- vapour interface then provides an indication of a vertical location of the liquid-vapour interface. According to examples of the present disclosure, the liquid-vapour phase transition pressure is based on a storage temperature of the ammonia. The liquid-vapour phase transition pressure is temperature dependent. Hence, by using a storage temperature of the ammonia as basis for the liquid-vapour phase transition pressure, the filling level may be determined more accurately. The storage temperature can be measured by a temperature sensor in communication with the tank system. Alternatively, the storage temperature can also be assumed to be constant, since the temperature in some waterbodies can be relatively constant, for example sufficiently far below the ocean surface. As another alternative, the storage temperature can be modelled or predicted by a temperature forecast model. According to examples of the present disclosure, the one or more pressure sensors comprises a first pressure sensor and a second pressure sensor positioned at different depths of the waterbody. The provision of several sensors may, for example, allow separate measurements of pressures in the gas phase and in the liquid phase of the stored ammonia, and or allow measurements of a differential pressure, both of which can be used to improve accuracy of a determined filling level. According to examples of the present disclosure, the measurement of the internal ammonia pressure is a differential pressure measurement using the first pressure sensor and the second pressure sensor. According to examples of the present disclosure, the filling level is provided based on a tank section inclination trajectory, e.g. the inclination of a pipe, herein referred to as pipe inclination trajectory. The inclination trajectory indicative of inclination along an extend of the one or more tank sections, e.g. in the form of pipes, relative to the one or more pressure sensors. Determination of a filling level based on a tank inclination trajectory can in particular be relevant in case the tank system is provided as one or more lengthy pipelines extending across an inclined ocean bed. According to examples of the present disclosure, the method comprises a step of arranging the one or more tank sections onto a bottom water floor of the waterbody, such as onto a seabed, wherein the tank system is arranged onto the bottom water floor such that at least one of the tank sections extend along the bottom water floor. For example, the bottom water floor has at least one inclined surface, wherein the tank system is arranged onto the bottom water floor such that the inclination of the inclined tank section, e.g. a pipe portion, arises from the inclined surface. Such an inclination can be utilized to provide a distinct bottom portion of the tank system, which in turn can be utilized for efficient removal of liquid ammonia and / or for determination of a filling level. According to examples of the present disclosure, the one or more tank sections is a plurality of tank sections, the plurality of tank sections comprising a first sub-group of tank sections collectively arranged in a first sub-rack and a second sub-group of tank sections collectively arranged in a second sub-rack, wherein the step of arranging the tank system in the waterbody comprises arranging the first sub-rack and the second sub-rack in a rack system. A rack system with several sub-groups of tank sections facilitates and simplifies maintenance, installation, expansion, and decommissioning of ammonia storage and handling systems. According to examples of the present disclosure, the method comprises a step of disconnecting the second sub-rack from the rack system, thereby reducing the inner ammonia-receiving volume of tank sections of a remainder of the plurality of tank sections of the rack system. According to examples of the present disclosure, the plurality of tank sections comprises a third sub-group of tank sections collectively arranged in a third sub-rack, wherein the method comprises a step of connecting the third sub-rack to the rack system to thereby increase the inner ammonia-receiving volume of the plurality of tank sections, wherein the step of connecting the third sub-rack is performed separately from the step of arranging the tank system in the waterbody. A third sub-group of tank sections can be provided at a later stage, separately from installing the rest of the tank system, to thereby expand the ammonia storage and handling system. That the step of connecting the third sub-rack to the rack system is performed separately from the step of arranging the tank system in the waterbody may be further quantified by a duration of time between the two steps. For example, the step of connecting the third sub- rack to the rack system is performed at least 1 month later than the step of arranging the tank system in the waterbody, for example at least 6 months, such as at least 12 months. According to examples of the present disclosure, the step of disconnecting the second sub- rack comprises vertically translating the second sub-rack to disconnect it from the rack system and / or the step of connecting the third sub-rack comprises vertically translating the third sub-rack to connect it to the rack system. By facilitating connection and disconnection of a sub-rack by vertical translation, such operations can be performed via a surface vessel, such as a ship, located directly above the tank system, thereby simplifying connection and disconnection of a sub-rack. According to examples of the present disclosure, tank sections of the plurality of tank sections are each arranged in an upright orientation such as vertically. Such arrangement of tank sections in a rack system generally simplifies the topology of the system in comparison with a system in which the tank sections are arranged horizontally. According to examples of the present disclosure, the filling of ammonia into the ammonia- receiving volume and / or the removal of ammonia from the ammonia receiving volume is performed via at least one pipeline fluidly connected to at least one of the at least one communication port. For example, a single pipeline can be interchangeably connected to an inlet port or an outlet port. According to examples of the present disclosure, the pipeline receives ammonia from an onshore of offshore ammonia production facility fluidly connected to the at least one pipeline. According to examples of the present disclosure, the ammonia production facility produces ammonia which is transferred to the at least one communication port at a temperature of at least 0 degrees Celsius, for example at least 10 degrees Celsius, for example at least 20 degrees Celsius, such as at least 30 degrees Celsius. For example, the storage and handling system according to the present disclosure may receive ammonia directly form a production facility which provides ammonia at cold temperature. According to examples of the present disclosure, removal of the ammonia from the ammonia- receiving volume comprises moving the removed ammonia to an external ammonia-receiving vessel such as a ship. For example, the storage and handling system according to the present disclosure may be used to provide ammonia to a bulk carrier configured to receive ammonia or used to provide ammonia to a vessel having an ammonia-based engine. According to examples of the present disclosure, the method further comprises removing vapor of ammonia from the ammonia-receiving volume, condensing the vapour, and returning the condensed vapour to the ammonia-receiving volume. According to examples of the present disclosure, the returning of the condensed vapour is carried out without cooling the condensed vapour, and by allowing the condensed vapour to be cooled in the ammonia-receiving volume by heat exchange with the waterbody. According to examples of the present disclosure, the tank system is provided with negative buoyancy when the inner ammonia-receiving volume is filled with ammonia in gas phase and the tank system is arranged in the waterbody. According to examples of the present disclosure, the ammonia-receiving volume of each of the one or more tank sections collectively form an inner unified volume of the one or more tank sections. According to examples of the present disclosure, the ammonia is stored together with a secondary gas, the secondary gas having a greater saturation vapour pressure than ammonia. The provision of a secondary gas to be stored together with ammonia may serve as a mechanism for reinforcing discharge of ammonia from the tank system to, e.g., a seafaring vessel receiving the ammonia. The secondary gas having a greater saturation vapour pressure than ammonia will primarily be in a gaseous phase within the inner ammonia- receiving volume. When discharging ammonia, for example through a communication port at a bottom portion of the tank system, the partial pressure provided by the secondary gas can provide a force which pushes ammonia out of the inner ammonia-receiving volume through the communication port. Due to the location of the port at the bottom portion of the tank system, it is primarily the ammonia, and not the secondary gas, which is discharged. This is due to the greater saturation pressure of the secondary gas. Therefore, ammonia can be more efficiently discharged. A smaller pump, or no pump at all, can potentially be used for removing / discharging ammonia. The secondary gas may be at least partly preserved in the inner ammonia-receiving volume and thereby be reused over time. Accordingly, the ammonia may be filled into the ammonia- receiving volume while at least a part of the secondary gas which has previously been used for pushing ammonia out of the inner ammonia-receiving volume is still present in the ammonia-receiving volume. At least 50 percent of the secondary gas may be reused from one step of pushing out a first batch of ammonia to a second step of pushing out a second batch of ammonia, which second batch has been filled into the ammonia-receiving volume after the first batch was emptied from the ammonia-receiving volume. Further, the provision of a secondary gas can ensure that a greater fraction of ammonia is in the liquid phase due to the increase of total pressure provided by the secondary gas. Accordingly, a larger total fraction of ammonia can be efficiently removed from the inner ammonia-receiving volume. During operation, the secondary gas acts as a mechanical spring which is compressed when ammonia is filled into the inner ammonia-receiving volume, and this compression can then be used to efficiently discharge ammonia from the inner ammonia-receiving volume. The same secondary gas may hence be present in the tank system during multiple cycles of filling and removing ammonia. The secondary gas may, for example, have a greater saturation vapour pressure than ammonia when stored in the inner ammonia receiving volume. The secondary gas may, for example, have a greater saturation vapour pressure than ammonia at a temperature at which it is stored in the tank system. The secondary gas may, for example, have a greater saturation vapour pressure than ammonia at a temperature in the range from 0 degrees Celsius to 10 degrees Celsius, for example a greater saturation vapour pressure than ammonia at a temperature of 5 degrees Celsius. Optionally, the secondary gas may be a gaseous mixture having several gaseous components. The saturation vapour pressure may also be referred to as a liquid-vapour phase transition pressure. According to examples of the present disclosure, the secondary gas comprises a chemically inert gas, such as diatomic nitrogen gas. The secondary gas may be a chemically inert gas. The chemically inert gas is preferably chemically inert in respect of ammonia and / or in respect of the tank system in which it is stored. Nitrogen gas is advantageous to utilize since it is relatively cheap, and since it does not significantly dissolve into liquid ammonia. According to examples of the present disclosure, the step of removing ammonia from the ammonia-receiving volume is performed by using the secondary gas to displace the ammonia out of the ammonia-receiving volume. According to examples of the present disclosure, the secondary gas is supplied into the ammonia-receiving volume as a step separate from the step of removing ammonia from the ammonia-receiving volume. Hence, the secondary gas may be supplied at a different point in time than ammonia, from a different source than ammonia, through a different communication port than ammonia, or any combination thereof. Such independent operation may ensure that the system is more flexible. According to examples of the present disclosure, the secondary gas is supplied to the ammonia-receiving volume through a communication port different from the communication port through which ammonia is filled into the ammonia-receiving volume. The secondary gas and ammonia may alternatively be supplied simultaneously. According to examples of the present disclosure, the ammonia is filled into the ammonia- receiving volume during simultaneous compression of the secondary gas as a result of the filling of the ammonia into the ammonia-receiving volume. Hence, if the secondary gas is already present in the ammonia receiving volume, filling ammonia into the ammonia-receiving volume will simultaneously compress this secondary gas. This compression can then ensure that sufficient pressure for efficiently discharging ammonia is present. According to examples of the present disclosure, the ammonia is removed from the ammonia-receiving volume without mechanically pumping the ammonia. Here, mechanically pumping may be defined as a process of feeding or removing the ammonia by a mechanical pump directly engages with the ammonia, for example by pushing or compressing the ammonia, for example based on converting electrical energy into hydraulic energy. According to examples of the present disclosure, a pressure in the inner ammonia-receiving volume at the liquid-vapour interface is greater than a waterbody pressure, the waterbody pressure being measured in the waterbody in which the tank system is arranged at the same depth of the waterbody as the liquid vapour interface, for example wherein the pressure in the inner ammonia-receiving volume at the liquid-vapour interface is in the range from 10 bar to 100 bar, for example in the range from 20 bar to 80 bar, for example in the range from 30 to 60 bar. The pressure of the secondary gas may exceed the pressure of the waterbody. These exemplified pressures may ensure efficient discharge of ammonia at typical water depths while not requiring too much energy to achieve. According to examples of the present disclosure, a pressure in the inner ammonia-receiving volume at which the ammonia and the secondary gas is stored is sufficiently great to discharge at least a part of the ammonia from the inner ammonia-receiving volume to the surface of the water body, for example via a discharge pipe for the ammonia. Such a pressure, which is sufficiently great to discharge at least a part of the ammonia from the ammonia-receiving volume to the surface of the water body, can be calculated based on the saturation vapour pressure of ammonia (determined by, e.g., temperature of the surrounding water body), the density of ammonia, and the actual water depth. Optionally, friction in the system may also be considered. As an estimate, the pressure has to be sufficiently great to support a vertical column of ammonia extending from the tank system to (above) the surface of the water body. A depth of the storage location at which the tank system is arranged is typically at least 10 meters, for example at least 20 meters, for example at least 50 meters. According to examples of the present disclosure, the ammonia is stored at a volume ratio of fluid to gas in a range from 8.0 to 0.4, for example from 6.0 to 0.5, for example from 4.0 to 0.6, for example from 3.0 to 0.8. If the ratio of fluid to gas is too high, the gas might not be capable of providing sufficient pressure to efficiently discharge the ammonia. If the ratio of fluid to gas is too low, the amount of ammonia stored is low. The ranges exemplified above may there ensure that an adequate amount of ammonia can be stored while also providing pressure sufficient to reinforce discharging of ammonia. According to examples of the present disclosure, the ammonia is stored with a partial pressure from gaseous ammonia which is less than a partial pressure from the secondary gas. Thereby, the intended functionality of the secondary gas may be obtained. A second aspect of the disclosure relates to an ammonia storage and handling system comprising: one or more tank sections to be arranged or arranged below a waterbody, wherein each of the one or more tank sections has an inner ammonia-receiving volume to form an inner unified volume of the one or more tank sections; and at least one communication port into the ammonia-receiving volume. The system further comprises at least one communication pipe for communication of ammonia between the ammonia-receiving volume and a position above the waterbody. The system may additionally comprise a source of a secondary gas, e.g. in the form of a secondary gas storage tank which could be separate from the inner ammonia-receiving volume. The secondary gas storage tank could e.g., be separated from the inner ammonia-receiving volume by a flow path allowing a flow of the secondary gas into the inner ammonia-receiving volume. The secondary gas storage tank may be located above the waterbody or in the waterbody. According to examples of the present disclosure, the one or more tank sections is a plurality of tank sections, the plurality of tank sections comprising a first sub-group of tank sections collectively arranged in a first sub-rack and a second sub-group of tank sections collectively arranged in a second sub-rack, wherein the first sub-group of tank sections is primarily for ammonia and therefore defines the ammonia-receiving volume and the second sub-group of tank sections is primarily for the secondary gas. The system may comprise an electronic controller configured to control a pressure of the secondary gas based on a setting, where the setting specifies a desired flow of ammonia out of the ammonia-receiving volume. The electronic controller may comprise computer processing means configured for processing software to provide the desired function. Particularly, it may comprise a transfer function determining the pressure of the secondary gas as a function of the setting and a waterbody- storage parameter. This waterbody-storage parameter may e.g. comprise one or more of the following a) a depth of the waterbody, b) a density of the waterbody, c) a flow friction in the lifting pipe, and d) a desired lifting height. The one or more tank sections may be pipe sections with a cylindrical shape. The system may have negative buoyancy when the system is arranged in a waterbody and the inner ammonia-receiving volume is filled with ammonia vapour at a temperature of 0 degrees Celsius and a pressure at the liquid-vapour phase transition pressure at 0 degrees Celsius. An ammonia storage and handling system according to the second aspect has a negative buoyancy when the system is arranged in a waterbody and when the ammonia-receiving volume is filled with ammonia vapour at a certain temperature and pressure. The liquid- vapour phase transition pressure varies by temperature and, according to the present aspect, the relevant temperature at which the liquid-vapour phase transition pressure should be determined is 0 degrees Celsius. This provides a phase transition pressure of 4.3 bar. Ammonia vapour under such conditions contribute to the density and are thus relevant for the buoyancy properties of the system. Further, the negative buoyancy may be determined relative to a waterbody having a density of 1.02 gram per cubic centimetre, corresponding to a typical density of seawater depending on temperature and salinity. Thereby, the ammonia storage and handling system according to the second aspect has a density which ensures that it does not float when there is no liquid ammonia in the ammonia- receiving volume. Generally, an ammonia storage and handling system according to the second aspect may provide or facilitate at least similar or the same advantages as the method of storing and handling ammonia according to the first aspect. The tank system of the first aspect may be implemented as the system according to the second aspect, and the system according to the second aspect may comprise features of the tank system of the first aspect. According to examples of the present disclosure, the one or more tank sections are at least partly filled with ammonia, such as a mix of ammonia in a vapor phase and a liquid phase. According to examples of the present disclosure, the tank system is arranged onto a bottom water floor of the waterbody. According to examples of the present disclosure, the one or more tank sections comprises a plurality of tank sections extending side by side in a rack system. According to examples of the present disclosure, the storage comprises at least one sub-rack being releasably attachable to a remainder of the rack system and comprising a sub-group tank sections of the plurality of tank sections. The tank sections could be sections of a pipe, particularly a pipe with a circular cross section. According to examples of the present disclosure, the system further comprises a release valve fluidly and releasably connecting an inner ammonia-receiving volume of the sub-group from an inner ammonia-receiving volume of remaining tank sections of the plurality of tank sections to allow removal of the sub-rack from the remaining rack system. According to examples of the present disclosure, the system further comprises a pump arranged in communication with one of the at least one communication ports. The pump may be provided as an alternative or in addition to the secondary gas source. According to examples of the present disclosure, the tank sections comprise a weight coating such as a concrete weight coating. A weight coating may contribute to provide the negative buoyancy. Other sources of negative buoyancy may be, e.g., parts of a rack system, shielding from surroundings, or an anchoring arrangement for fixing the system to the seabed. According to examples of the present disclosure, the one or more tank sections comprise a protective inner coating, an ammonia corrosive resistant material, a cathodic protection system, or any combination thereof; wherein the protective inner coating comprises epoxy coating, polyurethane coating, ammonia corrosion resistant lining, or any combination thereof; wherein the ammonia corrosive resistant material comprises a stainless steel such as 316L or a duplex stainless steel; wherein the cathodic protection system comprises at least one sacrificial anode within the one or more tank sections and / or an impressed current cathodic protection system. Hence, a protective inner coating, an ammonia corrosive resistant material, and / or a cathodic protection system may protect the ammonia storage and handling system, for example protect the one or more tank sections, from corrosion due to the presence of ammonia. Regular inspection and maintenance of the pipeline system may be performed to identify and / or address corrosion issues before they escalate. Further, examples of the disclosure may provide pH control / metering. Monitoring and controlling the pH of the ammonia can be a part of the ammonia corrosion control. Maintaining the ammonia within a specific pH range can reduce the risk of corrosion of the pipeline materials. Contamination of the ammonia with impurities or incompatible materials can accelerate corrosion. Proper handling / storage and measurement system can be implemented to prevent contamination or provide an overview of contamination of the ammonia system. According to examples of the present disclosure, the cylindrical shape of the one or more tank sections has a longitudinal extend of at least 5 meters, for example at least 15 meters, such as at least 50 meters, and / or wherein the cylindrical shape of the one or more tank sections has an outer transversal diameter of at least 0.3 meters, such as at least 0.5 meters, and / or of at most 3.0 meters, such as at most 2.0 meters. According to examples of the present disclosure, a combined longitudinal extend of the one or more tank sections is at least 1 km. According to examples of the present disclosure, a sum of the inner ammonia-receiving volume of the one or more tank sections is at least 100 cubic meters, for example at least 200 cubic meters, such as at least 400 cubic meters. According to examples of the present disclosure, the one or more tank sections is a plurality of tank sections arranged substantially parallel relative to each other in a rack. According to examples of the present disclosure, the tank system comprises one or more pressure sensors configured to measure an internal ammonia pressure in the ammonia- receiving volume to determine a filling level of ammonia based on the ammonia pressure. A third aspect of the present disclosure relates to use of one or more tank sections for storing ammonia in a waterbody, each of the one or more tank sections having a cylindrical shape with a longitudinal extend, wherein the cylindrical shape of the one or more tank sections may have an outer transversal diameter of at least 0.3 meters, such as at least 0.5 meters, and / or of at most 3.0 meters, such as at most 2.0 meters. The tank sections could be sections of a pipe, particularly a pipe with a circular cross-section. A fourth aspect of the present disclosure relates to a method of pressurizing a tank system storing ammonia, the tank system arranged at a water depth in a water body, the method comprising: - determining a lift height of the ammonia based on a height difference from the tank system to an outlet of the tank system, the outlet preferably being arranged above the water body, - determining a column pressure of the ammonia for the determined lift height, - determining a target pressure of the secondary gas based on the column pressure, and - pressurizing said tank system according to said target pressure at least partially based on supplying said secondary gas to the tank system. Such a method may allow for improved storage and discharge of ammonia, in particular discharge of ammonia with necessarily requiring a pump for discharging. According to examples of the present disclosure, the method further comprises a step of discharging ammonia from the tank system via said outlet based on the tank system being pressurized according to said target pressure due to the presence of the secondary gas. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention will now be further described by reference to the accompanying drawings, in which: Fig. 1 illustrates an ammonia storage and handling system according to an example of the present disclosure, Fig. 2 illustrates another ammonia storage and handling system according to an example of the present disclosure, Fig. 3 illustrates an ammonia storage and handling system in communication with an ammonia production facility and a seafaring vessel, Fig. 4 illustrates a sub-rack of a rack system according to an example of the present disclosure, Fig. 5 illustrates a rack system according to an example of the present disclosure, Fig. 6 illustrates addition or removal of a sub-rack of a rack system, Fig. 7a-b illustrate temperature-dependent liquid-vapour phase transition pressure and densities of ammonia, Fig. 8 illustrates a tank section having a non-horizontal longitudinal extension in combination with a measurement of an internal ammonia pressure used to determine a filling level, Figs. 9a-b illustrate a tank system based on a carrier pipe hosting at least two sub-pipes, Fig. 10 illustrates method steps according to an example of the present disclosure, Fig. 11 illustrates a further ammonia storage and handling system according to the present disclosure, and Figs. 12 and 13 illustrate examples of utilizing a secondary gas to provide pressure for discharging ammonia. DETAILED DESCRIPTION Fig. 1 illustrates an ammonia storage and handling system 3 according to an example of the present disclosure. The ammonia storage and handling system is also referred to as a tank system 3. The system 3 is arranged onto a bottom water floor, namely a seabed 6 of a waterbody 1. Thus, the system 3 is submerged in the waterbody 1 below the surface 8 of the waterbody. The system comprises a plurality of tank sections 5a, 5b, … 5n, in the present examples provided in the form of pipe sections. Each of these tank sections 5a, 5b, … 5n has a cylindrical shape with a circular circumference and a longitudinal extension transverse to the circular circumference. Further, each of the tank sections 5a, 5b, … 5n has an inner ammonia-receiving volume 13 for receiving and storing ammonia. Each of the tank sections 5a, 5b, … 5n are fluidly connected such that the ammonia-receiving volume 13 of each of the tank sections 5a, 5b, … 5n collectively form an inner unified volume of the tank 3. In this embodiment, the tank sections 5a, 5b, … 5n are fluidly connected by a connection manifold which fluidly couples each of the tank sections 5a, 5b, … 5n as well as a communication port 4. In the illustrations provided herein, tank systems are generally exemplified as pipe systems. However, generally, any type of tank sections can be used to implement tank systems according to the present disclosure. The system further comprises a communication port 4. In this example, the system 3 comprises a single communication port though which ammonia can be filled into the system 3 and through which ammonia can be removed from the system 3 as well. In other systems, ammonia is filled and removed through separate communication ports. The system 3 is used to store and handle ammonia. The ammonia is transferred into the system 3 via the communication port 4. The ammonia may generally be provided at any pressure or temperature. After being provided, the ammonia will then reach thermal equilibrium with the surrounding waterbody 1. Typically, the ammonia will thereby reach a partially condensed state in which some of the ammonia is in the form of liquid ammonia and some of the ammonia is in the form of gaseous ammonia. In the system 3, the vapour and liquid of ammonia thereby coexist at equilibrium. The liquid ammonia and the gaseous ammonia are separated by a liquid-vapour interface 7. In the illustrated example, the liquid-vapour interface 7 is illustrated to be at the same level in each of the tank sections 5a, 5b, … 5n. This is typically the case if the system is in equilibrium. If, hypothetically, the liquid-vapour interface 7 would be different in one of the tank sections 5a, 5b, … 5n, then, due to pressure difference at the interface 7 in the different tank sections 5a, 5b, … 5n, typically some liquid ammonia will evaporate and some gaseous ammonia will condense so as to approach the same liquid-vapour interface in the tank sections 5a, 5b, … 5n. Filing or removing operations may also result in different liquid-vapour interface levels. Alternative examples according to the present disclosure may be configured to store ammonia at different temperatures and / or at different pressures. In such alternative examples, the liquid-vapour interface level may typically differ among different tank sections. The ammonia storage and handling system 3 has been manufactured such that the system has a negative buoyancy. In practice, this is achieved by providing a sufficient density, for example by means of a weight coating such as a concrete weight coating, or some other structural arrangement. Typically, the storage system 3 will not be emptied of gaseous ammonia. This serves as an appropriate condition for the negative buoyancy. That is, the system 3 has negative buoyancy when the system 3 is arranged in the waterbody 1 and the inner ammonia- receiving volume is filled with ammonia vapour at a temperature of 0 degrees Celsius and a pressure at the liquid-vapour phase transition pressure at 0 degrees Celsius. The buoyancy is determined relative to a waterbody having a density of 1.02 gram per cubic centimetre. The buoyancy of the system is determined based on all components of the system, including the communication port 4, connection manifolds between tank sections 5a, 5b, … 5n, racks holding the tank sections 5a, 5b, … 5n, etc. In the waterbody 1, the system 3 is placed in a storage location 2 on the seabed 6, which is a location found suitable for receiving the system 3 prior to installation of the system 3. Generally, an ammonia storage and handling systems according to the present disclosure may further be fluidly connected by a connection manifold connected to an upper portion of each of the tank sections 5a, 5b, … 5n. Such an additional connection manifold may, for example, serve as a vapour return line in connection with an additional communication port, through which vapour can be return when unloading ammonia from the system to, e.g., a seafaring vessel. Further, an ammonia storage and handling system may additionally comprise one or more pumps at, e.g., the connection port for filling ammonia onto and / or unloading ammonia from the system. Fig. 2 illustrates another ammonia storage and handling system 3 according to an example of the present disclosure. In comparison with the system illustrated in Fig. 1, the tank sections 5a, 5b, … 5n of the system 3 illustrated in Fig. 2 are arranged serially in fluid communication with each other to form a single pipeline. To some extent, the illustrated pipeline has similarities with a conventional subsea pipeline for gas transportation. However, in the illustrated system 3, at least one end (more specifically both ends) of the pipeline terminates below the water surface. Further, the illustrated pipeline stores ammonia. The system 3 comprises a communication port 4 which is located at a bottom portion of the pipeline. Thereby, ammonia which is stored in partially condensed state can generally be efficiently removed from the system, since the communication port is in direct contact and communication with liquid ammonia. The communication port 4 can be located at a bottom portion of the pipeline by arranging the system onto a seabed 6 having an inclined surface as illustrated in Fig. 2. Optionally, a subsea pig launcher may be arranged at one end of a tank section of the system, wherein the subsea pig launched is configured to supply an inspection pig into at least one of the tank sections. In other examples according to the present disclosure, tank sections may be connected to form several pipelines. Optionally, the system may further comprise an additional communication port arranged in a top portion of the system, for example serving as a return line for vapour and / or an input line for filling the system with ammonia. One or more pumps may be arranged in communication with any communication port of the system. Fig. 3 illustrates an ammonia storage and handling system 3 in communication with an ammonia production facility 9 and a seafaring vessel 10. The illustrated system 3 comprises two communication ports 4a, 4b provided as a separate inlet port 4b and a separate outlet port 4a. Further, the system 3 comprises a pump 11 arranged at and in communication with the outlet port 4a. An onshore ammonia production facility 9 produces ammonia. The ammonia produced can be supplied via an ammonia supplying pump 12 from the ammonia production facility 9 to the system 3 via the inlet port 4b. From the system 3, ammonia can be supplied to a seafaring vessel 10 via the outlet port 4 using the pump 4. The ammonia can for example be supplied to the seafaring vessel 10 via a near shore jetty, an onshore terminal, a cryogenic offloading system / tower, an anchor-based offloading system, or a buoy-based offloading system. The figure further illustrates an optional vapour return line from the seafaring vessel 10 to the system 3 indicated by a dotted arrow. Thereby, ammonia vapour expelled from the seafaring vessel 10 due to the provision of liquid ammonia from the system 3 can be returned to the storage system 3. This return line may provide the vapour via one of the illustrated communication ports 4a, 4b, or via separate dedicated communication port. Fig. 4 illustrates a sub-rack 14 of a rack system according to an example of the present disclosure. The sub-rack 14 comprises a sub-group of tank sections 5 collectively arranged in the sub- rack 14 in an upright orientation. The sub-group of tank sections 5 may be fluidly coupled by a sub-rack manifold (not shown). Each of the individual tank sections have an outer diameter and a longitudinal extension transverse to the outer diameter. Each individual tank section 5 may have an outer diameter between 300 mm and 3000 mm, for example between 500 mm and 2000 mm. Each of the individual tank sections may have a longitudinal extension between 2 m and 30 m, for example between 3 m and 25 m, for example between 4 m and 20 m, such as between 5 m and 15 m. Fig. 5 illustrates a rack system 15 according to an example of the present disclosure. In the present example, the rack system 15 comprises a first sub-rack 14a and a second sub- rack 14b. Each of these sub-racks 14a, 14b may for example be similar to the sub-rack illustrated in Fig. 4. The rack system 15 is part of a tank system 3, the tank 3 further comprising at least one communication port 4 through which each of the sub-racks 14a, 14b may receive and / or discharge ammonia. Alternatively, each respective sub-rack 14a, 14b may have one or more dedicated communication ports. Each sub-rack 14a, 14b of the sub-rack system 15 is fluidly connected to the communication port 4 by a separate sub-rack separation valve 16a, 16b. This allows each the sub-racks to be fluidly connected and disconnected separately. In this particular example, the first sub-rack 14a is connected to the communication port 4 via a first sub-rack separation valve 16a, and the second sub-rack 14b is connected to the communication port 4 via a second sub-rack separation valve 16b. Fig. 6 illustrates addition or removal of a sub-rack 14d of a rack system 15. In rack systems according to the present disclosure, the sub-racks 14a-14d are preferably arranged in a horizontal array of sub-racks 14a-14d. This permits vertical addition or removal of a sub-rack from the rack system, for example using a seafaring vessel 10 as illustrated in fig. 6. Such an operation is typically associated with opening or closing a sub-rack separation valve as those schematically illustrated in Fig. 5. Generally, modularization as facilitated by a rack system 15 according to the present disclosure may simplify maintenance, installation, expansion, and / or decommissioning of the ammonia storage and handling system 3. Fig. 7a-b illustrate temperature-dependent liquid-vapour phase transition pressure 22 and densities of ammonia 25, 26. In Fig. 7a, the horizontal axis is a temperature scale in units of degrees Celsius, and the vertical axis is an absolute pressure scale in units of bar. The diagram illustrated in Fig. 7a thereby constitutes a pressure-temperature diagram with phase boundary 22, i.e., the liquid-vapour phase transition pressure 22. Below this phase transition pressure 22, ammonia is in a gaseous phase or vapour phase, and above this phase transition pressure 22, ammonia is in a liquid phase (assuming equilibrium). At the phase transition pressure 22, the liquid phase and the gaseous phase of ammonia can coexist in a partially condensed state. According to examples of the present disclosure, this is the state at which ammonia is preferably stored. In Fig. 7b, the horizontal axis is a temperature scale in units of degrees Celsius, and the vertical axis is a density scale in units of kilograms per cubic metre. The lower curve illustrates the density of the gaseous phase, i.e., the gas density 26, and the upper curve illustrates the density of the liquid phase, i.e., the liquid density 25. The left- hand axis applies for gaseous ammonia 26 and the right-hand axis applies for liquid ammonia 25. Fig. 8 illustrates a tank section 5 having a non-horizontal longitudinal extension in combination with a measurement of an internal ammonia pressure used to determine a filling level. The measurement can be understood in view of the diagrams illustrated in Figs. 7a-7b. In the schematic illustration, a single tank section 5 is considered for the sake of simplicity. The tank section is arranged on a seabed having a non-horizontal inclination. A first pressure sensor 17a is arranged at a bottom portion of the tank section 5, and a second pressure sensor 17b is arranged at a top portion of the tank section 5. Each of these pressure sensors 17a, 17b measure the internal ammonia pressure at the position at which they are respectively arranged. The illustrated system further comprises a temperature sensor 18. This sensor 18 is configured to measure the temperature of ammonia in the tank section 5. In this particular example, each of these three sensors 17a, 17b, 18 are communicatively connected to a processing unit 20, such as a programmable logic circuit. The processing unit 20 is configured to receive measurements from the sensors 17a, 17b, 18 to thereby provide a filling level indication 21. Such a processing unit 20 may be part of a tank system. It may be arranged submerged in a waterbody together with the rest of the tank system, or it may be arranged above the water body, for example at a terminal through which the tank system can be filled and / or discharged. The processing unit can also be located remotely. In order to understand how a filling level indication 21 is provided, a vertical scale 19 is also illustrated. A starting point for obtaining a filling level indication 21 is the temperature of the system. As evident from Figs. 7a-b, both the liquid-vapour phase transition pressure and the density of ammonia depends on the temperature. In the present example, the temperature of the system is measured using the temperature sensor 18. The obtained temperature can then be directly translated to a liquid-vapour phase transition pressure as well as a liquid density and a gas density, for example via the diagrams in Figs. 7a-b. This liquid-vapour phase transition pressure corresponds to the pressure at the liquid-vapour interface 7. This pressure further approximates the pressure in the tank section throughout the gaseous phase above the liquid-vapour interface 7. This includes the pressure at the second pressure sensor 17b. The pressure at the first pressure sensor 17a is the sum of the liquid-vapour phase transition pressure and an additional pressure provided by the hight of the vertical column of liquid ammonia above the first pressure sensor 17a. In the illustrated example, the hight of the vertical column of liquid ammonia is indicated on the vertical scale 19 by dashed lines extending horizontally therefrom to the liquid-vapour interface 7 and the first pressure sensor 17a. This pressure provided by the hight of the vertical column of liquid ammonia further depends proportionally on the density of liquid ammonia. This density can, e.g., be inferred from the measured temperature and the diagram illustrated in Fig. 7b. To obtain a filling level indication, a first pressure is measured by the first pressure sensor 17a and a second pressure is measured by the second pressure sensor 17b. The difference between the first pressure and the second pressure provides the pressure difference between the locations of the first pressure sensor 17a and the second pressure sensor 17b which corresponds approximately to the pressure provided by the hight of the vertical column of liquid ammonia above the first pressure sensor, taking into account the density of liquid ammonia. Thereby, an indication of the vertical hight of the liquid-vapour interface is obtained, which can be converted into to a volumetric filling level indication 21. With a tank section having a linear inclination as illustrated in the present example, the conversion from the vertical hight of the liquid-vapour interface into a volumetric filing level indication 21 is linear. The volumetric filling level indication may be converted into a mass of total ammonia or mass of liquid ammonia based on density. The operations and calculations explained above may be programmed into the processing unit 20 such that it can provide the filling level indication 21 based on the measurements. The present example relies on two pressure sensors 17a, 17b and a temperature sensor 18. However, fewer sensors can also be used. Instead of two pressure sensors, a single pressure sensor, for example arranged at a bottom portion of the tank section 5, can be used. Instead of measuring the pressure at a top portion of the tank section or tank system, the pressure here can be assumed to be approximately equal to the liquid-vapour phase transition pressure inferred from a temperature. Additionally, or alternatively, a temperature measurement can be omitted, for example be assuming a particular temperature of the water, or correspondingly, assuming a particular liquid-vapour phase transition pressure and / or density of ammonia. Typically, water temperatures do not vary greatly sufficiently far below the water surface of the ocean. A temperature can also be modelled or provided from an external source. The measurement principle laid forth above can be applied to tank systems comprising any number of tank sections arranged in any manner. In case of a non-trivial geometric configuration of the tank system, such as a non-linear inclination trajectory of the tank system as illustrated in Fig. 2, a conversion of the vertical column of liquid ammonia above the pressure sensor into a filling level indication can further take into account the geometry of the tank system to obtain a more precise filling level indication. Generally, the geometry of the tank system provides a functional relationship between the vertical column of liquid ammonia above the pressure sensor and the actual filling level. Further, the measurement procedure can be improved by taking into account the density of gaseous ammonia. Figs. 9a-b illustrate a tank system based on a carrier pipe 5 hosting at least two sub-pipes 27a, 27b, 27c. According to the present disclosure, ammonia can be stored in the at least two sub-pipes 27a, 27b, 27c of a carrier pipe as illustrated in these figures. Fig. 9a provides a cross-sectional view of a tank section 5 in the form of a carrier pipe hosting three sub-pipes 27a, 27b, 27c. Fig. 9b illustrates the tank system 3 comprising in inlet port 4, an outlet port 4a, a tank section 5 hosting the three sub-pipes 27a, 27b, 27c, as well as indications of possible fluid connections between the ports 4a, 4b and / or between the sub-pipes 27a, 27b, 27c. An indication of the plane of the cross-sectional view of Fig. 9a is also provided in Fig. 9b. The fluid connections between the ports 4a, 4b and / or between the sub-pipes 27a, 27b, 27c may also be configured to facilitate pigging, for example such that an inspection pig can be launched into a first sub-pipe 27a, move from the first sub-pipe 27a to a second sub-pipe 27b, and move from the second sub-pipe 27b into a third sub-pipe 27c via the fluid connections at the end of the tank section 5. A carrier pipe having at least two sub-pipes can provide a decreased risk of ammonia leakage to surroundings, facilitate pigging, and facilitate alternative ammonia filling and discharging scenarios, for example by filling via one sub-pipe and discharging via another sub-pipe. As an example, a tank section the form of a carrier pipe may have an outer diameter between 1 m and 3 m. As an example, a sub-pipe may have an outer diameter between 0.5 m and 1.3 m. Fig. 10 illustrates method steps S1-S5 according to an example of the present disclosure. The present example is a method of storing and handling ammonia. In a first step of the method S1, a storage location is selected in a waterbody. The storage location may be selected based on an inspection of the seabed to ensure that it can host a tank system as disclosed herein. The selection may further take infrastructure into account, such as infrastructure for loading ammonia into a tank system and / or infrastructure for removing ammonia from the tank system. The waterbody may preferably be a waterbody of seawater, but in principle, any suitable waterbody can be used. In another step of the method S2, a tank system is provided. The tank system comprises at least one communication port and one or more tank sections. Each of the one or more tank sections has a cylindrical shape and an inner ammonia-receiving volume in fluid communication with the at least one communication port. In another step S3, the tank system is arranged in the waterbody. More specifically, the tank system is arranged at the storage location in the waterbody. The tank system may be arranged in the waterbody via a seafaring vessel. The seafaring vessel can be a pipe-laying ship. In another step S4, ammonia is filled into the tank system through one of the at least one communication port. Thereby, the system can store ammonia. Ammonia is stored in a partially condensed state in which vapour and liquid of the ammonia is separated by a liquid- vapour interface. In another step S5, ammonia is removed from the ammonia-receiving volume through one of the at least one communication port. The ammonia can be removed through the same port as through which it is filled, or it can be removed through a different port. Both the step of filling the ammonia, and the step of removing the ammonia is performed while the pipe- sections are submerged in the waterbody. Optionally, the ammonia is stored together with a secondary gas. Fig. 11 illustrates a further ammonia storage and handling system 3 according to the present disclosure. The system comprises a plurality of tank sections 5a, 5b, … 5n, each of the tank sections 5a, 5b, … 5n has an inner ammonia-receiving volume 13 for receiving and storing ammonia, and the plurality of tank sections 5a, 5b, … 5n being fluidly connected such that the ammonia- receiving volume 13 of each of the tank sections 5a, 5b, … 5n collectively form an inner unified volume of the tank system 3. In this example, the tank sections 5a, 5b, … 5n are fluidly connected by a lower manifold which fluidly couples a lower portion of each of the tank sections 5a, 5b, … 5n, and fluidly connected by an upper manifold which fluidly couples an upper portion of each of the tank sections 5a, 5b, … 5n. The embodiment further comprises three communication ports 4a, 4b, 4c. A first communication port 4a is for receiving ammonia from an external ammonia source and is fluidly connected to the lower manifold. A second communication port 4b is for receiving a secondary gas in the form of a diatomic nitrogen gas and is fluidly connected to the upper manifold. A third communication port 4c is for discharging ammonia to an external receiver and is fluidly connected to the lower manifold. During use, a liquid-vapour interface 7 is present in the system. Above this interface 7, gaseous ammonia and the secondary gas is present, and below the interface 7, liquid ammonia is present. The secondary gas provides a pressure which can be used to discharge ammonia through the third communication port 4c to an external receiver. Preferably, no significant discharge of the secondary gas occurs while ammonia is discharged. Hence, ammonia can be filled onto and removed from the ammonia-receiving volume 13 multiple times while using the same secondary gas. If necessary, additional quantities of the secondary gas can be filled into the ammonia receiving volume via the second communication port 4b. While discharge of ammonia may occur without use of a pump, filling of ammonia and / or the secondary gas typically requires a pump. Such a pump may be part of the system 3, or it may be a pump of the external source. The concept of employing secondary gas has been explained in relation to Fig. 11, but note that any of the other examples of ammonia storage and handling systems described herein may also utilize a secondary gas such as nitrogen. Although it can be preferable to fill ammonia and a secondary gas through separate communication ports, it can also be possible to do so through the same port. Fig. 12 illustrates an example of utilizing a secondary gas to provide pressure for discharging ammonia. In the present example, nitrogen (N2) is used as the secondary gas, and as a driver for displacement of ammonia (NH3) out of the inner ammonia receiving volume. The illustrated system comprises an N2source 120, an N2compressor 121, an NH3source 122, a pump or an NH3 compressor 123, the tank system 3, and a discharge pipe 124 for communication of NH3 with a recipient 124, such as a seafaring vessel. To lift the ammonia to the outlet of the discharge pipe to the recipient 124, an additional pressure is necessary for overcome the liquid ammonium column at the specific water depth, PdH = NH3density × g × dH, where g is the acceleration coefficient 9.81 m / s2and dH is the lift height from the liquid NH3level (i.e., the liquid-vapou interface 7) to the outlet at the recipient 124. The tank pressure is defined by the two partial pressures P-NH3, and P-N2. The partial pressure from ammonia P-NH3depends on the water temperature, and ranges from approximately 6 bar at 10°C to 13 bar at 30°C, see also Fig. 7a. Considering, as an example, that a 50 m lift height is desired at a temperature 10°C, the density of ammonia is 620 kg / m3(see Fig. 7b), and the following pressure can be used to discharge ammonia. PdH= NH3density × g × dH = 620 kg / m3× 9.81 m / s2× 50 m = 304110 Pa = 3.04 bar. The tank pressure required to discharge ammonia is then the sum of the pressure PdH of the liquid ammonia column and the pressure provided by ammonia P-NH3 at 10°C, which is 6.05 bar + 3.04 bar = 9.1 bar. In practice, an additional pressure may be used to overcome friction loss in the pipeline and to provide a significant discharge rate. Fig. 13 illustrates another example of utilizing a secondary gas to provide pressure for discharging ammonia. In comparison with the system illustrated in Fig. 12, the system in Fig. 13 further comprises secondary gas storage tanks 130a-c. Generally, a secondary gas storage tank may serve as a buffer tank for a secondary gas, such as N2, to ensure that a sufficient pressure can be maintained in the tank system to allow efficient discharge of ammonia. Without a secondary gas storage tank, the pressure within the tank system may decrease significantly upon discharging ammonia, thereby potentially resulting in inefficient discharge. By providing one or more secondary gas storage tanks storing the secondary gas, the pressure within the tank system, and thereby the efficiency by which ammonia can be discharged, can be maintained more efficiently during ammonia discharge. In Fig. 13, various examples of placements of secondary gas storage tanks 130a-c are schematically provided. The N2source and the N2compressor may be connected directly to the ammonia-receiving volume of the tank system 3, or may be connected via one or more of the secondary gas storage tanks 130a-c. Further, any secondary gas storage tank is connected directly or indirectly with the ammonia-receiving volume of the tank system 3. In the present example, a secondary gas storage tank 130a is provided above the surface of the waterbody, a secondary storage tank 130b is provided within the water body at a height above the ammonia-receiving volume of the tank system 3, and a secondary storage tank 130c is provided at a height substantially the same or below the ammonia-receiving volume of the tank system 3. For a secondary gas storage tank 130c at a height substantially the same or below the ammonia-receiving volume of the tank system 3, the connection to the ammonia-receiving volume of the tank system may be provided via a one-way valve or via an elevated fluid connection (as schematically indicated in the figure) which at least partly prevents liquid flow of ammonia to the secondary gas storage tank 130c. A secondary gas storage tank provided above the surface of the waterbody may be arranged at the N2source 120. It is also possible to provide one or more secondary gas storage tanks as illustrated in Fig. 13 in systems not comprising an N2source or an N2compressor. LIST OF FIGURE REFERENCES: 1 waterbody 2 storage location 3 tank system 4 communication port 5 tank section or pipe section 6 seabed 7 liquid-vapour interface 8 surface of waterbody 9 ammonia production facility 10 seafaring vessel 11 pump 12 ammonia-supplying pump 13 ammonia-receiving volume 14 sub-rack 15 rack system 16 sub-rack separation valve 17 pressure sensor 18 temperature sensor 19 vertical scale 20 processing unit 21 filling level indication 22 liquid-vapour phase transition pressure 23 liquid phase 24 gaseous phase 25 liquid density 26 gas density 27 sub-pipe 120 N2source 121 N2compressor 122 NH3 source 123 NH3 compressor 124 recipient 125 water depth 130 secondary gas storage tank S1-S5 method steps

[0002] LIST OF NUMBERED EMBODIMENTS 1. A method of storing and handling ammonia, the method comprising the steps of: selecting a storage location in a waterbody; providing a tank system, the tank system comprising at least one communication port and one or more tank sections, wherein each of the one or more tank sections has an inner ammonia-receiving volume in fluid communication with the at least one communication port and, optionally, a cylindrical shape; arranging the tank system in the waterbody; filling ammonia through one of the at least one communication port, wherein the ammonia is stored in a partially condensed state in which vapour and liquid of the ammonia is separated by a liquid-vapour interface; and removing ammonia from the ammonia-receiving volume through one of the at least one communication port, wherein the step of filling the inner ammonia-receiving volume and the step of removing the ammonia is performed while the one or more tank sections are submerged in the waterbody. 2. The method according to embodiment 1, wherein the ammonia is filled into the inner ammonia-receiving volume during the step of filling without simultaneously removing ammonia vapour from the inner ammonia-receiving volume. 3. The method according to any of the preceding embodiments, wherein the step of filling ammonia into the inner ammonia-receiving volume is performed without simultaneously removing ammonia vapour from the inner ammonia-receiving volume and while condensing ammonia vapour in the inner ammonia-receiving volume. 4. The method according to any of the preceding embodiments, wherein the step of filling ammonia into the ammonia-receiving volume is performed while the ammonia which is provided to the ammonia-receiving volume has a temperature which is different from a temperature of the ammonia already present in the ammonia-receiving volume, and wherein the temperature of the ammonia which is provided to the ammonia-receiving volume is reduced or increased by heat exchange with the waterbody. 5. The method according to any of the preceding embodiments, wherein the at least one communication port comprises an inlet port and an outlet port separate from the inlet port, wherein the step of filling the inner ammonia-receiving volume is performed via the inlet port and the step of removing ammonia from the ammonia-receiving volume is performed via the outlet port. 6. The method according to embodiment 5, wherein the tank system is arranged in the waterbody such that a depth of the waterbody at the inlet port is less than a depth of the waterbody at the outlet port. 7. The method according to any of the preceding embodiments, wherein the ammonia is filled into the inner ammonia-receiving volume in gas phase and allowed to at least partially condense in the inner ammonia-receiving volume by heat exchange with the waterbody. 8. The method according to any of embodiments 1-6, wherein the ammonia is filled into the inner ammonia-receiving volume in liquid phase. 9. The method according to any of the preceding embodiments, wherein the method comprises a step of storing the ammonia provided in the step of filling the inner ammonia- receiving volume. 10. The method according embodiment 9, wherein a pressure in the inner ammonia-receiving volume at the liquid-vapour interface is different from a waterbody pressure, the waterbody pressure being measured in the waterbody in which the tank system is arranged at the same depth of the waterbody as the liquid vapour interface, for example different by a least 0.5 bar, for example different by at least 1.0 bar, for example different by at least 3.0 bar, for example different by at least 10 bar, such as different by at least 50 bar. 11. The method according to any of embodiments 9-10, wherein the ammonia is stored at a storage temperature which is within a temperature threshold of a surrounding waterbody temperature, wherein the storage temperature is measured within the ammonia-receiving volume and the waterbody temperature is measured in the waterbody in which the tank system is arranged within 2 meters of a position at which the storage temperature is measured and at least 0.5 meter away from the tank system, wherein the temperature threshold as at most 10 Kelvin, for example at most 5 Kelvin, such as at most 2 Kelvin. 12. The method according to any of the preceding embodiments, wherein one of the at least one communication port is a bottom communication port, the bottom communication port being arranged below the liquid-vapour interface when liquid ammonia takes up 10 % of volume of the ammonia-receiving volume. 13. The method according to embodiment 12, wherein the tank system comprises at least one pump arranged in communication with the bottom communication port, wherein the step of removing ammonia from the ammonia-receiving volume is performed using the at least one pump. 14. The method according to any of the preceding embodiments, wherein, during the step of removing the ammonia, the liquid-vapour interface is located above the one of the at least one communication port through which ammonia is removed. 15. The method according to any of the preceding embodiments, wherein the tank system is arranged in the waterbody such that a longitudinal extension of the one or more tank sections is different from a horizontal extension, the horizontal extension defined as being parallel with a surface of the waterbody. 16. The method according to any of the preceding embodiments, wherein the method comprises the steps of: positioning one or more pressure sensors onto the one or more pipe; performing a measurement of an internal ammonia pressure in the inner ammonia-receiving volume of the one or more tank sections using the one or more pressure sensors; and determining a filling level of ammonia based on the ammonia pressure. 17. The method according to embodiment 16, wherein at least one of the pressure sensors is positioned at a bottom portion of the tank system, the bottom portion positioned below the liquid-vapour interface when liquid ammonia takes up 10 % of volume of the ammonia- receiving volume. 18. The method according to any of embodiments 16-17, wherein at least one of the pressure sensors is positioned below the liquid-vapour interface during the step of performing a measurement. 19. The method according to any of embodiments 16-18, wherein the filling level is calculated based on liquid-vapour phase transition pressure. 20. The method according to embodiment 19, wherein the liquid-vapour phase transition pressure is based on a storage temperature of the ammonia. 21. The method according to any of embodiments 16-20, wherein the one or more pressure sensors comprises a first pressure sensor and a second pressure sensor positioned at different depths of the waterbody. 22. The method according to embodiment 21, wherein the measurement of the internal ammonia pressure is a differential pressure measurement using the first pressure sensor and the second pressure sensor. 23. The method according to any of embodiments 16-22, wherein the filling level is provided based on a pipe inclination trajectory, the pipe inclination trajectory indicative of inclination along an extend of the one or more tank sections relative to the one or more pressure sensors. 24. The method according to any of the preceding embodiments, wherein the method comprises a step of arranging the one or more tank sections onto a bottom water floor of the waterbody, such as onto a seabed, wherein the tank system is arranged onto the bottom water floor such that at least one of the tank sections extend along the bottom water floor. 25. The method according to any of the preceding embodiments, wherein the one or more tank sections is a plurality of tank sections, the plurality of tank sections comprising a first sub-group of tank sections collectively arranged in a first sub-rack and a second sub-group of tank sections collectively arranged in a second sub-rack, wherein the step of arranging the tank system in the waterbody comprises arranging the first sub-rack and the second sub-rack in a rack system. 26. The method according to embodiment 25, wherein the method comprises a step of disconnecting the second sub-rack from the rack system, thereby reducing the inner ammonia-receiving volume of tank sections of a remainder of the plurality of tank sections of the rack system. 27. The method according to any of embodiment 25-26, wherein the plurality of tank sections comprises a third sub-group of tank sections collectively arranged in a third sub-rack, wherein the method comprises a step of connecting the third sub-rack to the rack system to thereby increase the inner ammonia-receiving volume of the plurality of tank sections, wherein the step of connecting the third sub-rack is performed separately from the step of arranging the tank system in the waterbody. 28. The method according to any of embodiment 25-27, wherein the step of disconnecting the second sub-rack comprises vertically translating the second sub-rack to disconnect it from the rack system and / or the step of connecting the third sub-rack comprises vertically translating the third sub-rack to connect it to the rack system. 29. The method according to any of embodiment 25-28, wherein tank sections of the plurality of tank sections are each arranged in an upright orientation such as vertically. 30. The method according to any of the preceding embodiments, wherein the filling of ammonia into the ammonia-receiving volume and / or the removal of ammonia from the ammonia receiving volume is performed via at least one pipeline fluidly connected to at least one of the at least one communication port. 31. The method according to embodiment 30, wherein the pipeline receives ammonia from an onshore of offshore ammonia production facility fluidly connected to the at least one pipeline. 32. The method according to embodiment 31, wherein the ammonia production facility produces ammonia which is transferred to the at least one communication port at a temperature of at least 0 degrees Celsius, for example at least 10 degrees Celsius, for example at least 20 degrees Celsius, such as at least 30 degrees Celsius. 33. The method according to any of the preceding embodiments, wherein removal of the ammonia from the ammonia-receiving volume comprises moving the removed ammonia to an external ammonia-receiving vessel such as a ship. 34. The method according to any of the preceding embodiments, comprising removing vapor of ammonia from the ammonia-receiving volume, condensing the vapour, and returning the condensed vapour to the ammonia-receiving volume. 35. The method according to embodiment 34, wherein the returning of the condensed vapour is carried out without cooling the condensed vapour, and by allowing the condensed vapour to be cooled in the ammonia-receiving volume by heat exchange with the waterbody. 36. The method according to any of the preceding embodiments, wherein the tank system is provided with negative buoyancy when the inner ammonia-receiving volume is filled with ammonia in gas phase and the tank system is arranged in the waterbody. 37. The method according to any of the preceding embodiments, wherein the ammonia is stored together with a secondary gas, the secondary gas having a greater saturation vapour pressure than ammonia. 38. The method according to embodiment 37, wherein the secondary gas comprises a chemically inert gas, such as diatomic nitrogen gas. 39. The method according to any of embodiments 37-38, wherein the step of removing ammonia from the ammonia-receiving volume is performed by using the secondary gas to displace the ammonia out of the ammonia-receiving volume. 40. The method according to any of embodiments 37-39, wherein the secondary gas is supplied into the ammonia-receiving volume as a step separate from the step of removing ammonia from the ammonia-receiving volume. 41. The method according to any of embodiments 37-40, wherein the secondary gas is supplied to the ammonia-receiving volume through a communication port different from the communication port through which ammonia is filled into the ammonia-receiving volume. 42. The method according to any of embodiments 37-41, wherein the ammonia is filled into the ammonia-receiving volume during simultaneous compression of the secondary gas as a result of the filling of the ammonia into the ammonia-receiving volume. 43. The method according to any of the embodiments 37-42, wherein the ammonia is removed from the ammonia-receiving volume without mechanically pumping the ammonia. 44. The method according to any of embodiments 37-43, wherein a pressure in the inner ammonia-receiving volume at the liquid-vapour interface is greater than a waterbody pressure, the waterbody pressure being measured in the waterbody in which the tank system is arranged at the same depth of the waterbody as the liquid vapour interface, for example wherein the pressure in the inner ammonia-receiving volume at the liquid-vapour interface is in the range from 10 bar to 100 bar, for example in the range from 20 bar to 80 bar, for example in the range from 30 to 60 bar. 45. The method according to any of embodiments 37-44, wherein a pressure in the inner ammonia-receiving volume at which the ammonia and the secondary gas is stored is sufficiently great to discharge at least a part of the ammonia from the inner ammonia- receiving volume to the surface of the water body, for example via a discharge pipe for the ammonia. 46. The method according to any of embodiments 37-45, wherein the ammonia is stored at a volume ratio of fluid to gas in a range from 8.0 to 0.4, for example from 6.0 to 0.5, for example from 4.0 to 0.6, for example from 3.0 to 0.8. 47. The method according to any of embodiments 37-46, wherein the ammonia is stored with a partial pressure from gaseous ammonia which is less than a partial pressure from the secondary gas. 48. The method according to any of the preceding embodiments, wherein the tank system is a pipe system, wherein the one or more tank sections are one or more pipe sections. 49. An ammonia storage and handling tank system comprising: one or more tank sections, wherein each of the one or more tank sections has an inner ammonia-receiving volume to form an inner unified volume of the one or more tank sections; and at least one communication port into the ammonia-receiving volume, wherein the system has negative buoyancy when the system is arranged in a waterbody and the inner ammonia-receiving volume is filled with ammonia vapour at a temperature of 0 degrees Celsius and a pressure at the liquid-vapour phase transition pressure at 0 degrees Celsius. 50. The system according to embodiment 49, wherein the one or more tank sections are at least partly filled with ammonia, such as a mix of ammonia in a vapor phase and a liquid phase. 51. The system according to any of embodiments 49-50, wherein the tank system is arranged onto a bottom water floor of the waterbody. 52. The system according to embodiment 49-51, wherein the one or more tank sections comprises a plurality of tank sections extending side by side in a rack system. 53. The system according to embodiment 52, wherein the storage comprises at least one sub-rack being releasably attachable to a remainder of the rack system and comprising a sub-group tank sections of the plurality of tank sections. 54. The system according to embodiment 53, comprising a release valve fluidly and releasably connecting an inner ammonia-receiving volume of the sub-group from an inner ammonia-receiving volume of remaining tank sections of the plurality of tank sections to allow removal of the sub-rack from the remaining rack system. 55. The system according to any of embodiments 49-54, comprising a pump arranged in communication with one of the at least one communication ports. 56. The system according to any of embodiments 49-55, wherein the tank sections comprise a weight coating such as a concrete weight coating. 57. The system according to any of embodiments 49-56, wherein the one or more tank sections comprise a protective inner coating, an ammonia corrosive resistant material, a cathodic protection system, or any combination thereof; wherein the protective inner coating comprises epoxy coating, polyurethane coating, ammonia corrosion resistant lining, or any combination thereof; wherein the ammonia corrosive resistant material comprises a stainless steel such as 316L or a duplex stainless steel; wherein the cathodic protection system comprises at least one sacrificial anode within the one or more tank sections and / or an impressed current cathodic protection system. 58. The system according to any of embodiments 49-57, wherein the cylindrical shape of the one or more tank sections has a longitudinal extend of at least 5 meters, for example at least 15 meters, such as at least 50 meters, and / or wherein the cylindrical shape of the one or more tank sections has an outer transversal diameter of at least 0.3 meters, such as at least 0.5 meters, and / or of at most 3.0 meters, such as at most 2.0 meters. 59. The system according to embodiment 58, wherein a combined longitudinal extend of the one or more tank sections is at least 1 km. 60. The system according to any of embodiments 49-59, wherein a sum of the inner ammonia-receiving volume of the one or more tank sections is at least 100 cubic meters, for example at least 200 cubic meters, such as at least 400 cubic meters. 61. The system according to any of embodiments 49-60, wherein the one or more tank sections is a plurality of tank sections arranged substantially parallel relative to each other in a rack. 62. The system according to any of embodiments 49-61, wherein the tank system comprises one or more pressure sensors configured to measure an internal ammonia pressure in the ammonia-receiving volume to determine a filling level of ammonia based on the ammonia pressure. 63. The system according to any of embodiments 49-62, wherein the system further comprises at least one secondary gas storage tank separated from the inner ammonia- receiving volume by a flow path allowing a flow of the secondary gas into the inner ammonia- receiving volume. 64. The system according to embodiment 63, wherein at least one of the at least one secondary gas storage tank is located above the waterbody. 65. The system according to any of embodiments 63-64, wherein at least one of the at least one secondary gas storage tank is located in the waterbody. 66. The system according to any of embodiments 63-65, comprising an electronic controller configured to control a pressure of the secondary gas based on a setting, where the setting specifies a desired flow of ammonia out of the ammonia-receiving volume. 67. The system according to embodiment 66, wherein the electronic controller comprises a transfer function determining the pressure of the secondary gas as a function of the setting and a waterbody-storage parameter, the waterbody-storage parameter comprising at least one of a) a depth of the waterbody, b) a density of the waterbody, c) a flow friction in the lifting pipe, and d) a desired lifting height. 68. The system according to any of embodiments 49-67, wherein the system is connected to source of secondary gas, such as a nitrogen production facility, for example a facility comprising a compressor for supplying nitrogen to the system. 69. The system according to any of embodiments 49-68, wherein the tank system is a pipe system, wherein the one or more tank sections are one or more pipe sections, wherein each of the pipe sections has a cylindrical shape. 70. The system according to any of embodiments 49-69, wherein the tank system stores ammonia and, preferably, a secondary gas. 71. Use of one or more tank sections for storing ammonia in a waterbody, each of the one or more tank sections having a cylindrical shape with a longitudinal extend, wherein the cylindrical shape of the one or more tank sections has an outer transversal diameter of at least 0.3 meters, such as at least 0.5 meters, and / or of at most 3.0 meters, such as at most 2.0 meters. 72. A method of pressurizing a tank system (3) storing ammonia, the tank system arranged at a water depth in a water body, the method comprising: - determining a lift height of the ammonia based on a height difference from the tank system to an outlet of the tank system, the outlet preferably being arranged above the water body, - determining a column pressure of the ammonia for the determined lift height, - determining a target pressure of the secondary gas based on the column pressure, and - pressurizing said tank system according to said target pressure at least partially based on supplying said secondary gas to the tank system. 73. The method according to embodiment 71, wherein the method further comprises a step of discharging ammonia from the tank system via said outlet based on the tank system being pressurized according to said target pressure due to the presence of the secondary gas.

Claims

CLAIMS 1. A method of storing and handling ammonia, the method comprising the steps of: selecting a storage location (2) in a waterbody (1); providing a tank system (3), the tank system comprising at least one communication port (4) and one or more tank sections (5), wherein each of the one or more tank sections (5) has an inner ammonia-receiving volume (13) in fluid communication with the at least one communication port (4); arranging the tank system (3) in the waterbody (1); filling ammonia through one of the at least one communication port (4), wherein the ammonia is stored in a partially condensed state in which vapour and liquid of the ammonia is separated by a liquid-vapour interface (7); and removing ammonia from the ammonia-receiving volume through one of the at least one communication port (4), wherein the step of filling the inner ammonia-receiving volume and the step of removing the ammonia is performed while the one or more tank sections (5) are submerged in the waterbody (1), and wherein the ammonia is stored together with a secondary gas, the secondary gas having a greater saturation vapour pressure than ammonia.

2. The method according to claim 1, comprising a step of changing a condensed fraction of the ammonia by supplying or removing the secondary gas.

3. The method according to any of the preceding claims, wherein the ammonia is filled into the ammonia-receiving volume during simultaneous compression of the secondary gas as a result of the filling of the ammonia into the ammonia-receiving volume.

4. The method according to any of the preceding claims, wherein the ammonia is removed from the ammonia-receiving volume without mechanically pumping the ammonia.

5. The method according to any of the preceding claims, wherein a pressure in the inner ammonia-receiving volume at the liquid-vapour interface is greater than a waterbody pressure, the waterbody pressure being measured in the waterbody in which the tank systemis arranged at the same depth of the waterbody as the liquid vapour interface, for example wherein the pressure in the inner ammonia-receiving volume at the liquid-vapour interface is in the range from 10 bar to 100 bar, for example in the range from 20 bar to 80 bar, for example in the range from 30 to 60 bar.

6. The method according to any of the preceding claims, wherein a pressure in the inner ammonia-receiving volume at which the ammonia and the secondary gas is stored is sufficiently great to discharge at least a part of the ammonia from the inner ammonia- receiving volume to the surface of the water body, for example via a discharge pipe for the ammonia.

7. The method according to any of the preceding claims, wherein the ammonia is stored at a volume ratio of fluid to gas in a range from 8.0 to 0.4, for example from 6.0 to 0.5, for example from 4.0 to 0.6, for example from 3.0 to 0.

8.

8. The method according to any of the preceding claims, wherein the ammonia is stored with a partial pressure from gaseous ammonia which is less than a partial pressure from the secondary gas.

9. The method according to any of the preceding claims, wherein the secondary gas comprises a chemically inert gas, such as diatomic nitrogen gas.

10. The method according to any of the preceding claims, wherein the step of removing ammonia from the ammonia-receiving volume is performed by using the secondary gas to displace the ammonia out of the ammonia-receiving volume.

11. The method according to any of the preceding claims, wherein the secondary gas is supplied into the ammonia-receiving volume as a step separate from the step of removing ammonia from the ammonia-receiving volume.

12. The method according to any of the preceding claims, wherein the secondary gas is supplied to the ammonia-receiving volume through a communication port different from the communication port through which ammonia is filled into the ammonia-receiving volume.

13. An ammonia storage and handling tank system comprising: one or more tank sections, wherein each of the one or more tank sections has an inner ammonia-receiving volume to form an inner unified volume of the one or more tank sections; andat least one communication port into the ammonia-receiving volume, wherein the system has negative buoyancy when the system is arranged in a waterbody and the inner ammonia-receiving volume is filled with ammonia vapour at a temperature of 0 degrees Celsius and a pressure at the liquid-vapour phase transition pressure at 0 degrees Celsius.

14. The system according to claim 13, wherein the system further comprises at least one secondary gas storage tank separated from the inner ammonia-receiving volume by a flow path allowing a flow of the secondary gas into the inner ammonia-receiving volume.

15. The system according to any of claims 13-14, wherein the system is connected to source of secondary gas, such as a nitrogen production facility, for example a facility comprising a compressor for supplying nitrogen to the system.

16. The system according to any of embodiments 13-15, wherein the tank system stores ammonia and, preferably, a secondary gas.

17. A method of pressurizing a tank system (3) storing ammonia, the tank system arranged at a water depth in a water body, the method comprising: - determining a lift height of the ammonia based on a height difference from the tank system to an outlet of the tank system, the outlet preferably being arranged above the water body, - determining a column pressure of the ammonia for the determined lift height, - determining a target pressure of the secondary gas based on the column pressure, and - pressurizing said tank system according to said target pressure at least partially based on supplying said secondary gas to the tank system.

18. The method according to claim 13, wherein the method further comprises a step of discharging ammonia from the tank system via said outlet based on the tank system being pressurized according to said target pressure due to the presence of the secondary gas.

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