GB2594310A - Apparatus and method - Google Patents

Abstract

An apparatus 5 comprises a fuel production hub including a fuel production system. The apparatus is located in an aquatic environment and includes a fuel storage system 12 having input and output interfaces. A fuel discharging system 3 and 4, for discharging the produced fuel from the fuel storage system via the output interface to another location, is also disclosed. The apparatus may be floating and the fuel produced may be hydrogen, produced from the electrolysis of seawater. The power for the electrolysis process may be provided by power generating devices 8 on the apparatus or via a supply cable connected to the apparatus. A method of operating the apparatus is also disclosed.

Description

APPARATUS AND METHOD

This invention relates to a standalone floating, energy-production, energy-storage, and energy-discharging platform, in particular associated with hydrogen fuel and 5 associated products derived from seawater.

The continual drive to lower the cost of low or zero carbon-based technologies has seen all aspects of power-generating devices and ancillary assets targeted to realise these reductions. A major development has been to resolve challenges surrounding reliability and expense of offshore power. This has led to developers exploring floating devices and other novel methods to ease the burden of deployment and retrieval. This has provided some short-term cost benefits for installation operations and maintenance, but these benefits are often cancelled out by the added complexity, challenges, and cost of the balance of plant (BOP), the end result being that the life cycle cost of technologies producing low or zero carbon-based power is not being effectively addressed.

To date, most offshore low or zero carbon-based technologies have been designed and built to generate electricity at source and transfer the electrical power to the onshore grid. This requires a cable to shore for exporting the power as well as a complex array of highly specialised connections and power electronics to control and transmit the generated power safely to the grid. The associated cost represents a significant proportion of the overall project and is often made worse by the fact that many high energy offshore resources are positioned far from a suitable grid connection requiring long cables, many connectors and, in some cases, expensive electrical sub-stations. It is commonly understood that sub-sea cables and connectors are the major source of failures and insurance claims in the offshore energy sector. The intensive nature of installation and repairs associated with sub-sea cables, connections, and power electronics is not a new problem within the sector. Although sub-sea connector solutions have been employed to allow a simple switch-in switch-out procedure for devices, such a solution still requires costly marine operations for repairs/maintenance and has limits in the maximum power transmittable by the connection as well as still being subject to the high costs and risks relating to the overall system reliability. The extent of the challenge is set to increase within the sector owing to the introduction of new technologies such as floating offshore wind where power generation takes place even further offshore requiring higher voltages for transmission, longer cables, more connections and sensitive electronics.

Low or zero carbon-based technologies have to date been unable to achieve a reduction in cost, by simplification of the BOP, as they have been focused on generating and exporting electricity to the grid in line with the financial incentives (feed-in tariffs) available. Developers have targeted maximum power output for devices but have struggled with the exponential cost increase presented when upscaling the electronics. This coupled with the inherent reliability issues with sub-sea cables and sensitive electronics has produced a barrier for commercialisation of many ocean energy technologies.

Technologies that have already successfully reached commercial scale, such as offshore wind power-generating devices, have achieved impressive output figures and efficiency but owing to the intermittence and unpredictable nature of weather and the absence of a viable energy storage solution, a huge proportion of this power is being wasted. This is due to a misalignment of supply with demand from the grid, meaning that often power generated from offshore wind devices cannot be sold and therefore the turbines are shut down sitting idle during highly energetic periods.

Significant effort has been put into improving the power output and efficiency of low or zero carbon devices. However, less has been done to address some of the fundamental challenges including, life cycle cost, reliability, and energy distribution.

According to one aspect of the present invention, there is provided apparatus comprising an aquatic environment-located fuel-production hub including a fuel-production system, a fuel-storage system having input and output interfaces, and a fuel-discharging system for discharging fuel from the fuel-storage system by way of the output interface to another location.

According to a second aspect of the present invention, there is provided a method comprising producing a fuel source upon a fuel-production hub located in an aquatic environment, storing the fuel source in a fuel-storage system on the hub, the fuel storage system having input and output interfaces, and discharging the fuel from the fuel-storage system by way of the output interface to another location.

Owing to these aspects of the present invention, it is possible to generate, store and discharge a fuel source derived from water without any electrical cable to shore allowing a reduction in cost, by simplification of the BOP.

Preferably, the fuel-production hub is in the form of a floating hub. In one embodiment, the hub includes at least one power generating device attached thereto.

Advantageously, the fuel source produced on the hub is hydrogen, produced from water by electrolysis of the water.

The fuel-storage system preferably includes a plurality of pressure vessels.

The discharging to another location is, advantageously, to a vessel releasably connectable to the fuel-production hub.

The fuel-discharging system advantageously comprises a transfer pump or compressor, pipework, a reel and a lifting device for discharging fuel and, if desired, associated products derived from the water.

In addition, a wireless transmitter, receiver and control interface is provided for remote monitoring and operation.

The development of floating hubs that can generate, store and discharge a fuel source such as hydrogen and associated products derived from water without an electrical cable to shore is not only allowing a reduction in cost by simplification of the BOP but also allowing access to new previously untapped high energy sites.

In order that the present invention can be clearly and completely disclosed, reference will now be made, by way of example only, to the accompanying drawings, in which:-Figure la is a schematic longitudinal cross-sectional view of a first embodiment of a fuel production hub, Figure lb is a plan view from above of the fuel production hub of Figure 1a, Figure lc is a mid-ships cross-sectional view of the hub of Figure la, Figure 2 is a schematic cross-sectional view of a second embodiment of a fuel production hub, Figure 3 shows a schematic sectional view of a dedicated hydrogen fuel distribution vessel, Figures 4a to 4h shows a fuel discharging process for the hub as shown in Figures la to lc, and Figure 5a to 5f shows a fuel discharging process for the hub as shown in Figure 2.

Referring to Figures la to 1 c, a fuel-production hub is in the form of a standalone offshore floating platform 5 located in a sea environment. The floating platform 5 has a mono-hull structure but other structures are applicable including but not limited to multi-hull, spar and semi-submersible. The platform 5 is self-powering owing to the presence of a plurality of electrical power-generating turbines 8 connected to the hull of the platform 5 specifically aimed at (but not limited to) electricity generation from tidal movements. The turbines can either be fixed or be removable. For the laterally disposed turbines 8, they can be mounted to the sides of the platform 5 by way of a trunnion-in-slot arrangement allowing for the turbine to be removed by a lifting crane from a vessel for maintenance and repair purposes. In addition, the centrally located turbine 8 can be arranged to be lifted and lowered through a moon pool with hatches top and bottom of the platform 5. Once located in the desired position in the sea, the platform 5 is preferably tethered to the seabed, held in place using a suitable moorings arrangement attached at bow and stern mooring connection points 10.

Electricity generated by the plurality of turbines 8 enables electrical power to be generated onboard to self-power a fuel production system and thereby provide electricity for an electrolysis of seawater to produce a hydrogen fuel source.

Conventionally, electricity produced by low or zero carbon technologies requires conditioning for long distance transmission as well as to meet the onshore grid requirement. However, with onboard hydrogen fuel production, it is not necessary for conditioning for long distance transmission owing to the power requirements and close proximity of electrolysers of the fuel production system located inside an aft machinery space 11 of the platform 5.

The electrolysers of the fuel production system generate Hydrogen from seawater by way of electrolysis using electricity from the turbines 8 and either seawater directly from the sea in which the platform 5 is located or fresh water produced on board from seawater via a reverse osmosis plant located in a forward machinery space 6 of the platform 5. Seawater can also be used for the cooling of the electrolysis system thereby saving further water usage. The electrolysers may be of the polymer electrolyte (PEM) type or, alternatively the anion exchange membrane (AEM) type, or any other suitable type of electrolyser.

Hydrogen that is generated by the fuel production system in the electrolysis process is, advantageously, compressed and piped from the electrolysers into one or more hydrogen fuel-storage tanks 12. The tanks may be fixed or removable that can be installed/removed via a hydraulic self-locking hatch 7 in the platform 5. For safety, the storage tanks 12 are positioned centrally of the hull structure to provide maximum protection from collision, as well as being segregated from all other areas/machinery by way of watertight and fire-resistant bulkheads and/or doors. The storage tanks also include an inlet interface through which hydrogen is introduced into the storage tanks and an outlet interface through which hydrogen is discharged from the storage tanks to a fuel discharging system. In addition, for further safety, the space in which the storage tanks 12 are located is vented to atmosphere with ducts routed out through the super structure elevated access hatch 2, to disperse leaks and prevent any unwanted gas build-up. A separate discharge vent 23 is also present, exiting at the elevated access hatch region to allow the storage tanks 12 to be purged if necessary.

When the storage tanks 12 are full or nearly full, discharge of the fuel source can take place. The scheduling and implementation of the discharging process can be done autonomously by remote communications and control commands sent and received via the transmitter and receiver antennas located on the mast 1. Wireless communications and notifications can also be sent to surrounding vessels including designated distribution vessels to inform on available quantity and scheduling of discharge to meet an available weather window. Additionally, this same information can be communicated to the global market to enable brokered transactions to take place.

When a discharging operation has been initiated, the distribution vessel is notified, and a suitable time slot confirmed. Such a dedicated hydrogen fuel distribution vessel is shown in Figure 3. However, the hydrogen fuel source can be discharged to any visiting vessel including but not limited to, ferries, cargo vessels, bulk carriers, workboats, and cruise ships. Alternatively, discharge of produced hydrogen fuel using electricity generated from tidal movements can also take place via a conduit or pipeline which would need a dynamic pipe/hose extending down to the seabed and onto a desired destination. With reference to Figures 4a to 4h, the visiting vessel attaches mooring lines to the platform 5 at dedicated mooring points (Figures 4a to 4c). When successfully moored alongside the platform 5, the vessel is held in position (Figure 4d) and hydrogen is subsequently discharged through the outlet interface and the fuel discharging system from the storage tanks 12 and discharged to the moored vessel, the fuel discharging system comprising a hose running from a powered reel 3, a lifting device in the form of a davit 4 and pumps located in the forward machinery space 6 of the platform 5 (Figures 4e and 4f). In practice, a free end (filling end) of the hose is payed out over the davit 4 and connected to the tank/tanks on board the vessel, into which hydrogen and associated product(s) can be transferred using the pumps. The vessel can then be freed from its mooring to the platform 5 and leave the vicinity to continue its journey (Figures 4g and 4h).

Referring to Figure 2, the standalone floating platform 5' has a cylindrical hull structure. However, other designs are applicable including but not limited to, mono hull, multi-hull, spar and semi-submersible. Unlike the embodiment shown in Figures la to lc this platform 5' does not feature onboard power generation. Instead, electricity is provided by one or more supply cables connected to the platform 5' at an entrance region 14' and the platform 5' is to be positioned near to a low or zero carbon, power generating device producing electricity (including but not limited to, an offshore wind park, tidal array, floating solar, or nuclear power station). The ability for the platform 5' to be connected to and take power from a near-by existing tidal-operated power generation device or an array thereof is particularly advantageous. Once in position, the platform 5' is tethered to the seabed and held in place using a suitable moorings arrangement attached at mooring connection points 10'. With a suitably scaled-up power feed, the storage capacity and overall platform takes a larger form compared to that of Figures 1 a to lc and can include a hydrogen liquefaction system 16' to increase the storage and discharge capability. Incoming electricity provides the power required to the electrolysers 19' of the fuel production system for hydrogen production. The electrolysers 19' and BOP generate hydrogen from water by way of electrolysis using electricity from the external supply and either directly with seawater or fresh water produced on board from seawater via the reverse osmosis desalination plant 21'.

Hydrogen generated by the fuel production system is piped to the liquefaction system 16' (if applicable) where it is pressurised, cooled and liquified. The hydrogen is then pumped into the main hydrogen storage tanks 12'. As with the platform 5 of Figures 1 a to 1c the hydrogen storage tanks 12' are positioned centrally to provide maximum protection from collision as well as being segregated from all other areas/machinery by way of watertight and fire-resistant bulkheads and/or doors. In addition, for further safety, the storage space is vented to atmosphere with ducts routed out through the super structure to disperse leaks and prevent any unwanted gas build up. A separate discharge vent 23' is also present, exiting the top region of the super structure to allow the storage tanks to be purged if necessary.

In normal operating conditions, the platform 5' and all ancillary systems are powered by the incoming electricity supply. However, the onboard hydrogen supply can also be used to power the platform 5' itself. In this respect, a hydrogen fuel cell 18' can take hydrogen from the storage tanks 12' and convert this into electricity for self-supply. A minimum quantity of hydrogen may be held in reserve to ensure long-term sustained operation of the platform 5' and, if necessary, safe shut down can be performed without a requirement for the main feed of electricity.

When the onboard storage tanks 12' are full or nearly full, discharging can take place. As previously mentioned, the scheduling and implementation of the discharging process can be done autonomously by remote communications and control commands sent and received via the transmitter and receiver antennas located on the mast 1'.

When a discharging operation has been initiated, the vessel is notified and a suitable time slot confirmed. Hydrogen can then be discharged to any visiting vessel. The platform 5' includes a plurality of fuel discharge system points to suit weather conditions or for simultaneous discharging. It is also possible to discharge via an export pipeline. With reference to Figures 5a to 5f, the visiting vessel can attach mooring lines (not shown) to the platform 5' at the dedicated mooring points 25'. When connected, the visiting vessel is held in position and hydrogen is discharged from the storage tanks 12' and transferred to the collecting vessel via the or each fuel discharge system comprising the hose with reel 3' or a hinged pipe arrangement running from the davit 4'. The hose or hinged pipe provides freedom of movement to allow for movement of the vessel and platform during filling. By controlling the position of the davit 4' and vessel, the free end (filling end) of the hose/hinged pipe can be guided over the other vessel and to the desired filling point on the vessel for connection. Once the hose/hinged pipe has been connected to the tank/tanks onboard the vessel, hydrogen and associated product(s) are transferred using the pumps of the fuel discharge system.

Referring to Figure 3, a dedicated hydrogen distribution vessel 30 has a mono hull design, but multi-hull and other designs are also applicable. The vessel 30 includes onboard hydrogen storage tanks 32 which are used to carry hydrogen as fuel to power the vessel 30 itself. For safety, the hydrogen storage tanks are positioned centrally of the vessel to provide maximum protection from collision as well as being segregated from all other machinery by way of watertight and fire-resistant bulkheads and/or doors. In addition, for further safety the storage space is vented to atmosphere with ducts routed out through the super structure, to disperse leaks and prevent any unwanted gas build up. A separate discharge vent is also present, exiting at the mast 38 to allow the storage tanks to be purged if necessary.

Hydrogen from the onboard storage tanks 32 is taken and piped to a hydrogen fuel cell 40 where it is converted to electricity to power an electric propulsion system 42 and all other auxiliary systems.

A large open cargo deck is present with space for transporting and filling portable hydrogen tanks 44 and other cargo. Loading and unloading of the vessel can be done either by roll-on/roll-off (RORO) using a bow door or by lifting with use of a deck crane 46.

The vessel supports wireless communications with the shore and the floating platform 5 or 5'. Autonomous scheduling for onloading and distribution can be achieved with use of software and remote communications via the transmitter and receiver antennas located on the mast 1 and 1'. Status updates are communicated constantly to enabling key data to be monitored actively to inform the scheduling of onloading and distribution. The key data for decision making includes but is not limited to the transit route, transit rate, weather forecast, fuel consumption, tank level/ pressure, and the planned discharge schedule for the hydrogen platform.

A plurality of platforms 5, 5' can be grouped together in order to increase the capacity zo of docking vessels.

By physically separating power production from the onshore grid and using hydrogen as a medium for energy storage, supply and demand can be better synchronised. This is made possible by the creation of a new commodity-based distribution network that makes use of the already existing shipping industry.

Eliminating the requirement for an export cable and the vast majority of the power electronics also provides an extremely effective mitigation of costs, as well as improving reliability, reducing risk, and opening new opportunities to exploit remote resources, where suitable grid connection may not be available or economically viable.

The highly anticipated development of floating offshore wind is a prime candidate to benefit from this approach given that the devices will be located further offshore requiring high voltages for transmission, longer cables, more connections and sensitive electronics.

The use of offshore low or zero carbon-based technologies has the prospect of producing large quantities of clean hydrogen known as green hydrogen, without the need for fossil fuels. The vast majority of the world's hydrogen is made using methods that emit vast quantities of carbon and consume large quantities of water for production and cooling. One of the key issues of producing renewable energy from wind, solar, wave or tidal energy is the intermittency of production. The production may also be at full capacity at a time when the grid does not need the power and with no sustainable means of storing the power it is of no use. By producing hydrogen instead of electricity can ensure that all production is fully utilised, the discharging operations and onward distribution can be actively managed and scheduled to suit weather windows and the market demands at the time. Additionally, there is a near infinite and free source of water from the surrounding seawater for production and cooling.

Maritime transport emits around 940 million tonnes of CO2 annually and is responsible for about 2.5% of global greenhouse gas (GHG) emissions (3rd IMO GHG study). By producing bulk hydrogen in offshore locations this could provide an effective means of fuelling maritime transport vessels.

The present invention provides a highly advantageous commercial position over existing offshore devices providing a new market opportunity for the sale of hydrogen and associate products derived from seawater either directly for fuelling shipping or for bulk forwarding to other customers. The reduced CAPEX and OPEX offered enable a lower life cycle cost to be realised pushing technology closer to commercialisation and inter-technological competitiveness. Further commercial advantages are brought forth by the mobility of the device being able to capture energy at remote location previously not viable as well as the benefits of not being tied to any particular site providing freedom to move locations with less time/cost.

Additionally, the present invention eliminates issues with labour intensive accessibility as well as inability to perform routine maintenance in the field. Ability to remotely monitor and control the system as well as easy access to the floating platform 5, 5' by boat offering unencumbered access to all system components enables rapid response in-the-field maintenance, thereby reducing downtime.

Claims (2)

1. Claims 1. According to one aspect of the present invention, there is provided apparatus comprising an aquatic environment-located fuel-production hub including a fuel-production system, a fuel-storage system having input and output interfaces, and a fuel-discharging system for discharging fuel from the fuel-storage system by way of the output interface to another location.
2. 2. According to a second aspect of the present invention, there is provided a method comprising producing a fuel source upon a fuel-production hub located in an aquatic environment, storing the fuel source in a fuel-storage system on the hub, the fuel storage system having input and output interfaces, and discharging the fuel from the fuel-storage system by way of the output interface to another location.