Sea-going cargo carrier

Abstract

A sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines comprises liquefied hydrogen (LH2) tanks 10, hydrogen boil-off gas (BOG) compressors 18, compressed hydrogen containers 22 to store the compressed hydrogen, and pipework 24 to supply the compressed hydrogen to the back-up engines. The compressors compress the BOG from the liquefied hydrogen tanks to provide compressed hydrogen. The primary driving mechanism can be one or more of an internal combustion engine, a hydrocarbon-fuel engine, or one or more sails. The cargo carrier can be a liquefied gas carrier or a goods carrier. When the cargo carrier is a liquefied hydrogen carrier, it can have liquefied hydrogen tanks which are able to provide hydrogen BOG as a back-up engine fuel source. The BOG compressors can compress the BOG from the liquefied hydrogen tanks to a pressure above 200 barg. The compressed hydrogen containers can be isotainers.

Description

According to a first aspect of the present invention, there is provided a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, comprising: (i) one or more liquefied hydrogen tanks; Qi) one or more hydrogen boil-off gas (BOG) compressors to compress BOG from the one or more liquefied hydrogen (LH2) tanks and provide compressed hydrogen; (iii) one or more compressed hydrogen containers to store the compressed hydrogen from step (b); and (iv) pipework to supply the compressed hydrogen to the one or more back-up engines. Optionally, the primary driving-mechanism of the sea-going cargo carrier is one or more of the group comprising: an internal combustion engine, a hydrocarbon-fuel engine, one or more sails. Optionally, the sea-going cargo carrier is a liquefied gas carrier or a goods carrier. Optionally, the sea-going cargo carrier is a liquefied hydrogen carrier having one or more liquefied cargo hydrogen tanks, able to provide hydrogen BOG as a back-up engine fuel source. Optionally the sea-going cargo carrier includes pipework to load and to unload liquefied hydrogen into and out of the one or more liquefied hydrogen cargo tanks. Optionally the one or more hydrogen BOG compressors is able to compress the boil-off gas from the one or more liquefied hydrogen tanks to a pressure above 200 barg. Optionally at least one of the one or more compressed hydrogen containers is an isotainer. Optionally the or each isotainer is a 20ft or 40ft isotainer. Optionally the or each hydrogen container is relocatable off-carrier. Optionally the or all of the one or more compressed hydrogen containers is an isotainer, and each or all of the isotainers is relocatable off-carrier. Optionally the compressed hydrogen is supplied to the one or more back-up engines at a pressure between 5-15 barg. According to a second aspect of the present invention, there is provided a method of part-powering a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, comprising: (a) providing liquefied hydrogen (LH2) on the sea-going cargo carrier in one or more liquefied hydrogen tanks; (ii) providing boil-off gas (BOG) from the one or more liquefied hydrogen tanks to one or more hydrogen BOG compressors to provide compressed hydrogen; (iii) storing the compressed hydrogen in one or more compressed hydrogen containers; and (iv) providing the compressed hydrogen to the one or more back-up engines. Optionally, the sea-going cargo carrier is as defined herein. Optionally, the method further comprises the step of relocating the or each hydrogen container off the sea-going cargo carrier. Optionally, the or all of the one or more compressed hydrogen containers is an isotainer, and each or all of the isotainers is relocatable off the sea-going cargo carrier. According to a third aspect of the present invention, there is provided a system of providing back-up engine-power to a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, the sea-going cargo carrier comprising: (i) one or more liquefied hydrogen (LH2) tanks; (ii) one or more hydrogen boil-off gas (BOG)_ compressors to compress BOG from the one or more liquefied hydrogen tanks and provide compressed hydrogen; (iii) one or more compressed hydrogen containers to store the compressed hydrogen from step (b); and (iv) pipework to supply the compressed hydrogen to the one or more back-up engines; the system comprising providing the liquefied hydrogen on the sea-going cargo carrier in the one or more liquefied hydrogen tanks, providing boil-off gas (BOG) from the one or more liquefied hydrogen tanks to the one or more hydrogen BOG compressors to provide the compressed hydrogen, storing the compressed hydrogen in one or more compressed hydrogen containers, and providing the compressed hydrogen to the one or more back-up engines. The system of the present invention can include the embodiments described herein in relation to the sea-going cargo carrier and method of the present invention as described herein, and the skilled person can understand how to develop each and every embodiment of the present invention described herein with each and every other embodiment described herein. Detailed Description The present invention will now be described in more detail and by way of example only, and with reference to the accompanying drawings in which: Figure 1 schematically shows method, apparatus and system embodiments of the present invention: and Figure 2 diagrammatically shows a further embodiment of the present invention. In the field of transportation of goods by sea, such goods generally being termed "cargo”, there are many types of sea-going cargo carriers. The shipping industry is seeking to reduce its carbon footprint in many ways, as the amount of fuel and the types of fuel used are major issues concerning powering sea-going cargo carriers. Many cargo carriers are transitioning away from traditional fuels towards liquified gas fuels such as LNG and LPG, etc. Meanwhile, the hydrogen fuel market is increasingly being considered as an alternative fuel source due to its avoidance of carbon dioxide (CChj-exhaust gas emissions. Hydrogen can be stored in either gas, or liquid form (typically termed "LH2"), although the storage of liquified hydrogen is advantageous because of its higher energy density and transportation efficiency. In current consideration is for a sea-going cargo carrier to be wholly or substantially powered by a hydrogen-fuelled engine. However, until such technology is better developed and commercialised, sea-going cargo carriers will still require to have a primary (i.e. providing >50% of the) driving-mechanism, such as an internal combustion engine, or gaseous hydrocarbon-fuelled engine, or other means of propulsion including one or more sails. Vessels provided with at least one rigid sail or other type of sail installation, with an appropriate mast structure, are already being built, or sails are being retrofitted to existing vessels, which allow the wind to provide a substantial proportion of the driving-power to sea-going cargo carriers. However, because of the further benefit of using a hydrogen-fuelled engine for environmental purposes, it can still be desired to have a back-up hydrogen-fuelled engine on a sea-going cargo carrier, independently of the primary drivingmechanism. The one or more back-up engines useable in the present invention are only required to provide a minority of the driving-mechanism of the cargo carrier, such as providing less than 40%, less than 30%, less than 20%, less than 15%, or even less, of the driving mechanism. Thus, the present invention at least provides a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, comprising: (i) one or more liquefied hydrogen tanks; (ii) one or more hydrogen boil-off gas (BOG) compressors to compress BOG from the one or more liquefied (LH2) hydrogen tanks and provide compressed hydrogen; (hi) one or more compressed hydrogen containers to store the compressed hydrogen from step (b); and (iv) pipework to supply the compressed hydrogen to the one or more back-up engines. As mentioned above, the primaiy driving-mechanism of the sea-going cargo carrier may be one or more of the conventional types of known ship propulsion, including the traditional types of internal combustion engine, the increasingly common gaseous hydrocarbon-fuel engines, ammonia-fuel engines, and now increasingly the use of one or more sails. The present invention relates to a sea-going cargo carrier that may carry any form of cargo, typically over longer sea or ocean journeys. The present invention is not limited by the nature of the cargo. However, in one embodiment of the present invention, the sea-going cargo carrier is a liquified gas carrier. Liquified gas carriers include a range of vessels able to transport various types of liquified gas, including LNG, LPG, ethanol, ethane, ethene, propane, propylene, ammonia, as well as liquified hydrogen itself. Thus, according to one embodiment of the present invention, the sea-going cargo carrier is a liquified hydrogen carrier, optionally using one or more sails as its primary driving-mechanism by wind. Liquified hydrogen tanks, i.e. tanks able to store liquefied hydrogen, for a sea-going cargo carrier are known in the art. There has been development of large-scale sea transportation of liquid hydrogen for more than 20 years, involving the creation of various shaped and sized storage tanks, based on ultra-low temperatures, optionally at above ambient pressures, and possibly with the use of coffer dams to maintain such ultra-low temperatures during transportation. A liquid hydrogen tanker is already commercially in use, and further ships and other sea-going vessels are intended to be built. Tank design and hull design for liquid hydrogen carriers is being discussed in the art in relation to building liquid hydrogen cargo vessels scalable to 40,000 m3 per storage tank. In the present invention, where the one or more liquid hydrogen tanks are intended to provide fuel to a back-up engine, the size, shape and design of the one or more liquified hydrogen tanks may not require to be all of the size of liquid hydrogen cargo-transportation tanks discussed hereinbefore. Hydrogen storage technologies based on using liquid organic hydrogen carriers (LOHCs) are also known in the art. The technology, mechanisms and pipework able to load liquified hydrogen into one or more liquified hydrogen tanks on a sea-going cargo carrier are known in the art, and are not further discussed herein. It is known that during the sea transportation of liquified gases, heat ingress from the warmer ambient surroundings and the movement of the liquified gases causes some evaporation in the form of a boil-off gas, typically abbreviated to "BOG”. In the field of liquified hydrocarbon gas transportation such as LNG transportation, it is known to seek to reliquefy the BOG from the cargo tanks, in order to maximise the recovery of the cargo during the sea-going voyage. This is typically achieved by the use of one or more hydrocarbon compressors, followed by known cooling and reliquefaction techniques. The present invention uses one or more hydrogen BOG compressors to compress the boil-off gas from the one or more liquified hydrogen tanks, and to provide a compressed hydrogen, as a compressed hydrogen stream. Hydrogen gas compressors are known in the art, and include those based on the diaphragm principle which is able to compress hydrogen to high or even extremely high pressures of more than 5,000 barg (75k PSI), or those using reciprocating compressors, where lower pressures such as <250 barg (3.6K PSI) may be desired. Other known gaseous hydrogen compressors are typically based on using positive displacement compressors or centrifugal compressors to achieve the hydrogen compression. The compressed hydrogen containers used in the present invention to store the compressed (but still gaseous) hydrogen provided by the one or more hydrogen BOG compressors may comprise any suitable containers known in the art. Such containers can store compressed hydrogen at a pressure above ambient, typically at a pressure of at least 100 barg, 200 barg, 300 barg, or even 400 barg, such as but not limited to 350 barg. One form of compressed hydrogen container is an isotainer. Isotainers for storing and possibly transporting liquified gases are already well known in the art, and are commercially used for storing gases such as natural gas, oxygen, argon, nitrogen and the like. In one embodiment of the present invention, one or more of the compressed hydrogen containers is a '20ft’ or a ‘40ft’ isotainer. The use of 20ft and 40ft ISO transport containers is well known in the art for the transportation of many goods and cargos, to the extent that such containers are now generically termed as "20ft ISO containers" and "40ft ISO containers”. 20ft and 40ft isotainers able to store for transportation purposes liquified gases is now regulated under various transportation regulations, including ASME code 8 div 1 and ISO-Type 75. Optionally, at least one of the one or more compressed hydrogen containers is an isotainer. Optionally, all of the one or more compressed hydrogen containers is or are isotainers, in particular one or more of 20ft or 40ft isotainers. In one embodiment of the present invention, the or each hydrogen container is relocatable off-carrier. That is, at least one, optionally all, of the one or more hydrogen containers, can be transportable away from and off the sea-going cargo container to another location. Optionally another location is another vessel, but typically such a location is an on-shore transportation means, such as a suitable lorry or trailer, able to transport the hydrogen container to a place of use, typically by road or rail. Where one or more of the compressed hydrogen containers is a isotainer, or particularly a 20ft or 40ft isotainer, road or rail transportation of such isotainers is already well known. In this way, any compressed hydrogen remaining in the one or more compressed hydrogen containers at the end of a voyage of the sea-going cargo carrier, or at a suitable intermediate point or port, can be relocated off-carrier for use either at a suitable on-shore facility or location, or for transportation elsewhere. Any compressed hydrogen container relocated off-carrier, can be replaced by a suitable empty compressed hydrogen container, to allow the present invention to continue on the next voyage of the sea-going cargo carrier. In another embodiment, any compressed hydrogen remaining in the one or more compressed hydrogen containers at the end of a voyage of the sea-going cargo carrier, or at a suitable intermediate point or port, can be piped off the cargo carrier via suitable pipework, for use either at a suitable on-shore facility or location, or for sending elsewhere. During loading of any liquefied gas onto the cargo carrier at a loading facility, there are tank-vapour return pipelines for the conventional vapour return from the cargo tanks that occurs during loading, and such vapour return pipework also may be useable in the present invention to assist off-loading any compressed hydrogen remaining in the one or more compressed hydrogen containers at the end of a voyage. The present invention includes supply pipework required to supply the compressed hydrogen to the one or more back-up engines. Hydrogen-fuelled engines for marine propulsion are known in the art, and are not further described herein. Optionally, such supply pipework includes one or more pressure-reduction means, valves and the like, to reduce or otherwise step down the pressure of the compressed hydrogen in the compressed hydrogen containers to a lower pressure more suitable for a hydrogen-fuelled back-up engine. Optionally, such supply pipework includes one or more flow controls, such as control valves, to help regulate the flow of the hydrogen from the compressed hydrogen containers to the back-up engine. Optionally, such supply pipework includes one or more buffer tanks to help pressure-reduction or flow control or both between the compressed hydrogen containers and the back-up engine. Buffer tanks are known in the art and can help regulate gas-flow from one or more tanks to a downstream demand. The present invention provides a suitable arrangement and system for using hydrogen BOG from one or more liquified hydrogen tanks on a sea-going cargo carrier, for one or more back-up engines. Engines using hydrogen as a fuel are known in the art, and are increasingly being developed both for efficiency, and for reduction of carbon-based exhaust gases. The present invention further requires pipework to supply the compressed hydrogen in the one or more compressed hydrogen containers to the one or more back-up engines for use as the engine fuel. Where the primary driving-mechanism of the sea-going cargo carrier still uses an internal combustion engine or gas- or hydrogen-fuel engine, the present invention still provides an overall reduction in the carbon emissions of the sea-going cargo carrier for the times where the sea-going cargo carrier is using a hydrogen fuelled back-up engine. Where the primary driving-mechanism of the sea-going cargo carrier involves alternative mechanisms such as one or more sails or other mechanisms not involving a hydrocarbon-fuel, the use of hydrocarbon BOG as per the present invention as the fuel for one or more back-up engines, provides a technology and system whereby the carbon-emissions of the sea-going cargo carrier could be wholly or substantially reduced to zero. The benefits of a sea-going cargo carrier having zero-carbon emissions are clear in the art and do not require further explanation. Thus, the present invention also provides a method of part-powering a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, comprising: (a) providing liquefied hydrogen on the sea-going cargo carrier in one or more liquefied hydrogen tanks; (ii) providing boil-off gas (BOG) from the one or more liquefied hydrogen tanks to one or more hydrogen BOG compressors to provide compressed hydrogen; (iii) storing the compressed hydrogen in one or more compressed hydrogen containers; and (iv) providing the compressed hydrogen to the one or more back-up engines. Thus, the present invention also provides a system of providing back-up enginepower to a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, the sea-going cargo carrier comprising: (i) one or more liquefied hydrogen tanks; (ii) one or more hydrogen boil-offgas (BOG) compressors to compress boil-off BOG from the one or more liquefied hydrogen tanks and provide compressed hydrogen; (iii) one or more compressed hydrogen containers to store the compressed hydrogen from step (b); and (iv) pipework to supply the compressed hydrogen to the one or more back-up engines; the system comprising providing the liquefied hydrogen on the sea-going cargo carrier in the one or more liquefied hydrogen tanks, providing boil-off gas (BOG) from the one or more liquefied hydrogen tanks to the one or more hydrogen BOG compressors to provide the compressed hydrogen, storing the compressed hydrogen in one or more compressed hydrogen containers, and providing the compressed hydrogen to the one or more back-up engines. Referring to the drawing, the accompanying schematic Figure 1 shows parts of a sea-going cargo carrier according to embodiments of the present invention. In Figure 1, there are shown four liquified hydrogen tanks 10, each tank 10 being able to store liquid hydrogen in a manner known in the art. Liquid hydrogen can be supplied to the tanks 10 during loading at a suitable quay dock, harbour or the like, through a suitable liquid inlet stream 12, with subsequent distribution pipework 14 into each tank 10, and suitable vapour-return pipework 17 to return vapour from the tanks 12 during loading in a conventional manner. Once the tanks 10 are supplied, the liquid inlet stream 12 is stopped, to begin the voyage of the cargo carrier. During the voyage of the cargo carrier, heat ingress from the warmer ambient surroundings movement of the liquified hydrogen in the tanks 10 will create evaporated hydrogen vapour in a manner known in the art. Such hydrogen vapour is termed hydrogen BOG (boil-off gas). They hydrogen BOG can be collected from at or near the top of each tank 10 by suitable pipework 16, and supplied to a hydrogen BOG compressor 18. They hydrogen compressor 18 is able to compress the hydrogen BOG to provide compressed hydrogen as a compressed hydrogen stream, which can be provided via a suitable distribution pipework 20 into one or more of four isotainers 22. Such isotainers may be 20ft or 40ft isotainers known in the art for storing liquified or compressed gas. The isotainers 22 can provide a stream of hydrogen via suitable pipework 24, and optionally via a buffer tank 26, towards one or more back-up engines (not shown) via a supply line 28, typically after pressure reduction through one or more pressure reduction valves 30. In an example of the present invention, a sea-going cargo carrier has a primary driving-mechanism based on one or more sails, which can provide at least the majority of the power required to drive the cargo carrier, such as at least 60%, or 70%, or 80% or higher. In this example of the present invention, the sea-going cargo carrier is a liquified hydrogen carrier, and the hydrogen can be stored as a liquid at a temperature of around -250°C in vacuum insulated cargo tanks. However, the skilled person can see that the present invention can be used on other sea-going cargo carriers, requiring less or smaller liquified hydrogen tanks. In the example of the present invention, the liquified hydrogen can be loaded and unloaded using conventional methods and techniques, typically involving deckmounted piping 12 on the cargo carrier. During transportation, hydrogen BOG is produced, and this can be compressed by one or more hydrogen BOG compressors to a pressure of above 300 barg, such as around 350 barg, for storage in one or more suitable 20ft or 40ft isotainers. Where the back-up engine is required, the compressed BOG can be provided as the fuel, typically following a reduction of pressure to a suitable lower pressure such as around 10 barg. Surplus compressed BOG that was not required during the voyage of the sea-going cargo carrier, can then be offloaded. Figure 1 also shows an example of the off-loading of any surplus compressed hydrogen gas remaining in the compressed hydrogen containers 22 at the end of a voyage of the sea-going cargo carrier, via suitable pipework 32 from the pipework 24 from the buffer tank 26, optionally into the existing return-vapour pipework 17, as a gaseous hydrogen stream 34. The hydrogen stream 34 can be at any suitable pressure at or below the pressure in the compressed hydrogen tanks 22. Such hydrogen stream 34 could be for use either at a suitable on-shore facility or location, or for sending elsewhere. Figure 2 shows an alternative embodiment for off-loading any surplus compressed hydrogen gas remaining in the compressed hydrogen containers at the end of a voyage of a sea-going cargo carrier 34. The surplus compressed hydrogen gas can be off-loaded at a dockside 36 in the one or more compressed hydrogen containers themselves, once suitably disconnected from their associated pipework in the carrier 34. At the dockside 36, a suitable portal 39 in the carrier 34 can be opened to provide access for a suitable transfer apparatus, such as a forklift truck 38 or the like, to offload one or more of the compressed hydrogen containers from the carrier 34. Where the one or more compressed hydrogen containers are 20ft isotainers 40 as shown in Figure 2, such containers can be easily manoeuvred and located onto a suitable on-shore road truck 42 for easy transportation to another location for their on-shore use. Such istainers 40 can then be replaced by similar but empty hydrogen containers (not shown), to allow the present invention to be ready for use for the next voyage of the sea-going cargo carrier 34. The present invention provides a sea-going cargo carrier, method and system, that reduces carbon-emissions of a sea-going cargo carrier, optionally to wholly or substantially zero, where the primary driving-mechanism is also a non-carbon emitting mechanism.

Claims

1. A sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, comprising:(i) one or more liquefied hydrogen (LH2) tanks;(ii) one or more hydrogen boil-off gas (BOG) compressors to compress BOG from the one or more liquefied hydrogen tanks and provide compressed hydrogen;(iii) one or more compressed hydrogen containers to store the compressed hydrogen from step (b); and(iv) pipework to supply the compressed hydrogen to the one or more back-up engines.

2. A sea-going cargo carrier as claimed in claim 1 wherein the primary drivingmechanism is one or more of the group comprising: an internal combustion engine, a hydrocarbon-fuel engine, one or more sails.

3. A sea-going cargo carrier as claimed in claim 1 or claim 2 wherein the seagoing cargo carrier is a liquefied gas carrier or a goods carrier.

4. A sea-going cargo carrier as claimed in claim 3 being a liquefied hydrogen carrier having one or more liquefied cargo hydrogen tanks, able to provide hydrogen BOG as a back-up engine fuel source.

5. A sea-going cargo carrier as claimed in claim 4 wherein the sea-going cargo carrier includes pipework to load and to unload liquefied hydrogen into and out of the one or more liquefied cargo hydrogen tanks6. A sea-going cargo carrier as claimed in any one of the preceding claims wherein the one or more hydrogen BOG compressors is able to compress the boiloffgas from the one or more liquefied hydrogen tanks to a pressure above 200 barg.

7. A sea-going cargo carrier as claimed in any one of the preceding claims wherein at least one of the one or more compressed hydrogen containers is an isotainer.

8. A sea-going cargo carrier as claimed in claim 7 wherein the or each isotainer is a 20ft or 40ft isotainer.

9. A sea-going cargo container as claimed in any one of the preceding claims wherein the or each hydrogen container is relocatable off-carrier.

10. A sea-going cargo carrier as claimed in claim 9 wherein the or all of the one or more compressed hydrogen containers is an isotainer, and each or all of the isotainers is relocatable off-carrier.

11. A sea-going cargo carrier as claimed in any one of the preceding claims wherein the compressed hydrogen is supplied to the one or more back-up engines at a pressure between 5-15 barg.

12. A method of part-powering a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, comprising:(a) providing liquefied hydrogen on the sea-going cargo carrier in one or more liquefied hydrogen tanks;(ii) providing boil-off gas (BOG) from the one or more liquefied hydrogen tanks to one or more hydrogen BOG compressors to provide compressed hydrogen;(hi) storing the compressed hydrogen in one or more compressed hydrogen containers; and(iv) providing the compressed hydrogen to the one or more back-up engines.

13. A method as claimed in claiml2 wherein the sea-going cargo carrier is as defined in any one of claims 1 to 11.

14. A method as claimed in claim 12 or claim 13 further comprising the step of relocating the or each hydrogen container off the sea-going cargo carrier.

15. A method as claimed in claim 14 wherein the or all of the one or more compressed hydrogen containers is an isotainer, and each or all of the isotainers is relocatable off the sea-going cargo carrier, optionally onto road or rail transportation.

16. A system of providing back-up engine-power to a sea-going cargo carrier having a primary driving-mechanism and one or more back-up engines, the seagoing cargo carrier comprising:(i) one or more liquefied hydrogen tanks;(ii) one or more hydrogen BOG compressors to compress boil-off gas (BOG) from the one or more liquefied hydrogen tanks and provide compressed hydrogen;(iii) one or more compressed hydrogen containers to store the compressed hydrogen from step (b); and(iv) pipework to supply the compressed hydrogen to the one or more back-up engines;the system comprising providing the liquefied hydrogen on the sea-going cargo carrier in the one or more liquefied hydrogen tanks, providing boil-off gas (BOG) from the one or more liquefied hydrogen tanks to the one or more hydrogen BOG compressors to provide the compressed hydrogen, storing the compressed hydrogen in one or more compressed hydrogen containers, and providing the compressed hydrogen to the one or more back-up engines.18

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