GB2595959A

GB2595959A - Apparatus and method

Info

Publication number: GB2595959A
Application number: GB2105320.2A
Authority: GB
Inventors: James Parkinson Richard
Original assignee: Hydrowing Ltd
Current assignee: Hydrowing Ltd
Priority date: 2020-04-23
Filing date: 2021-04-14
Publication date: 2021-12-15
Also published as: GB2594310A; GB202005931D0; GB202105320D0

Abstract

An apparatus 5 comprises a standalone tidal environment-located fuel-production hub including at least one tidal turbine 8 as a primary power-generating device and a fuel production system driven by power generated from the at least one tidal turbine. The apparatus further 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 hub is thus free from any electrical export cable to an onshore location. The apparatus may be floating and the fuel produced may be hydrogen, produced from the electrolysis of seawater. A method of operating the apparatus is also disclosed. Also disclosed is a standalone fuel-production hub with a power input connection (14’, Fig 2) connectable to a power generating device separate from the hub, and a method of operation.

Description

APPARATUS AND METHOD

This invention relates to a standalone floating, energy-production, energy-storage, and energy-discharging platform, in particular associated primarily with tidal energy, and 5 for producing hydrogen fuel and 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/expense surrounding reliability and maintenance 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, all tidal energy technologies have been designed and built to generate electricity at source and transfer the electrical power to an onshore grid. This requires a cable to shore for exporting the power as well as a complex array of highly specialised cable protection equipment, 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 still provides the greatest element of technical, operational and commercial risk for tidal energy projects owing to the exposure four times a day to some of the most dynamic conditions on the planet.

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 equipment and 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.

Tidal 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. The inherent high risk of installing, operating, maintaining and replacing these highly sensitive and extremely expensive sub-sea electrical equipment in highly dynamic tidal environments provides a major commercial barrier for access to lower costs of finance, further prohibiting the route to market for the sector.

Tidal energy-harvesting sites are often found in remote locations where grid connections have limited capacity or where a grid is isolated from the mainland national grid. This means that, for every tidal project, onshore works are required to implement connections and/or sub-stations adding additional complexity and the potential for large capital costs in order to implement grid upgrades to be able to handle the total tidal energy power potential. In addition to cost this is a time-consuming process requiring a multitude of stakeholders and national and/or governmental bodies to implement, thereby providing an additional barrier to large scale tidal energy development. Those sites which do have a connection to date are often limited in the amount of guaranteed power which can be exported onshore and therefore revenue generated, presenting a cashflow uncertainty for developers and their investors. In addition, if the electrical demand is low from the grid and tidal generation is high then the power generated cannot be exported resulting in loss of revenue unless additional storage systems are in place.

According to one aspect of the present invention, there is provided apparatus comprising a standalone tidal environment-located fuel-production hub including at least one tidal turbine as a primary power-generating device attached to the hub, a fuel-production system driven by power generated from the at least one tidal turbine, 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, the arrangement being such that the hub is free from any electrical export cable to an on-shore location.

According to a second aspect of the present invention, there is provided a method comprising producing a fuel source upon a standalone fuel-production hub located in a tidal environment by way of at least one tidal turbine as a primary power-generating device attached to the hub, storing the fuel source in a fuel-storage system on the hub, 113 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, the hub being free from any electrical export cable to an on-shore location.

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

According to a third aspect of the present invention, there is provided apparatus comprising a standalone fuel-production hub including a fuel-production system, a fuel-storage system having input and output interfaces, a fuel-discharging system for discharging fuel from the fuel-storage system by way of the output interface to another location, and a power input connection region connectable to a power generating device separate from the hub, the arrangement being such that the hub is free from any electrical export cable to an on-shore location.

According to a fourth aspect of the present invention, there is provided a method comprising producing a fuel source upon a standalone fuel-production hub, storing the fuel source in a fuel-storage system on the hub, the fuel storage system having input and output interfaces, discharging the fuel from the fuel-storage system by way of the output interface to another location, and importing power for the fuel-production hub from a power generating device separate from the hub and being connectable thereto, the hub being free from any electrical export cable to an on-shore location.

Owing to these aspects, the hub is able to take power from an existing power generation device or an array thereof.

Preferably, the fuel-production hub is in the form of a floating hub.

Secondary energy sources such as wind, solar or onboard battery storage may be present to help support systems during periods of low or no energy production, for example during slack tides.

Advantageously, the fuel source produced on the hub is hydrogen, produced from water by electrolysis of the water. Further products may be harvested from the process including oxygen, or hydrogen can be further processed to produce products such as ammonia.

A system which is free from an electrical export cable and thus not grid-connected, but instead creates hydrogen, eliminates all of the cost, risk and constraints associated with sub-sea electrical infrastructure and grid power acceptance. This enables all the energy from such a technology to be utilised all the time to produce a valued commodity providing greater certainty in generation and revenue cashflows.

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 certain applications, a storage pressure differential may be utilised to eliminate the need for pumps or compressors.

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 la, Figure lc is a mid-ships cross-sectional view of the hub of Figure 1 a, 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 zo 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 I c, a fuel-production hub is in the form of a standalone offshore floating platform 5 located in a tidal 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 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 moonpool with hatches top and bottom of the platform 5. The turbines 8 are not limited by these arrangements, but can also include, for example, arrangements where the turbines are lifted up through a cofferdam or managed from beneath via divers and/or a remotely operated underwater vehicle.

Once located in the desired position in the sea, the platform 5 is preferably tethered to 10 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 113 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 paid 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 or imported by one or more supply cables connected to the platform 5' at a power entry 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 lc 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 20 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 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

Claims 1. Apparatus comprising a standalone tidal environment-located fuel-production hub including at least one tidal turbine as a primary power-generating device attached to the hub, a fuel-production system driven by power generated from the at least one tidal turbine, 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, the arrangement being such that the hub is free from any electrical export cable to an on-shore location.
2. Apparatus according to claim 1, wherein the fuel-production hub is a floating hub.
3. Apparatus according to claim 1 or 2, and further comprising a secondary energy source.
4. Apparatus according to any preceding claim, and further comprising electrolysers to produce a hydrogen fuel source from water.
5. Apparatus according to any preceding claim, wherein the fuel-storage system includes a plurality of pressure vessels.
6. Apparatus according to any preceding claim, and further comprising a mooring point for a vessel to releasably connect to the fuel-production hub.
7. Apparatus according to claim 6, and further comprising a plurality of mooring points distributed around the fuel-production hub.
8. Apparatus according to any preceding claim, wherein the fuel-discharging system comprises a transfer pump, pipework, a reel and a lifting device for discharging fuel.
9. Apparatus according to any preceding claim, and further comprising a wireless transmitter, receiver and control interface.
10. Apparatus according to any preceding claim, and further comprising a reverse osmosis plant.
11. Apparatus according to any preceding claim, and further comprising a liquefication system.
12. Apparatus according to any preceding claim, and further comprising a hydrogen fuel cell.
13. A method comprising producing a fuel source upon a standalone fuel-production hub located in a tidal environment by way of at least one tidal turbine as a primary power-generating device attached to the hub, 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, the hub being free from any electrical export cable to an on-shore location.
14. A method according to claim 13, wherein said producing is producing hydrogen fuel.
15. A method according to claim 13 or 14, wherein the discharging is carried out autonomously by remote communications and control commands sent and received via the transmitter and receiver antennas.
16. A method according to any one of claims 13 to 15, wherein said discharging comprises notifying a distribution vessel of a docking opportunity, confirming a suitable time slot for the vessel, mooring the vessel alongside the fuel-production hub, discharging the fuel through the outlet interface, the fuel discharging system comprising a hose running from a powered reel, a lifting device and pumps, and once said discharging is complete, freeing the vessel from its mooring to the hub.
17. Apparatus comprising a standalone fuel-production hub including a fuel-production system, a fuel-storage system having input and output interfaces, a fuel-discharging system for discharging fuel from the fuel-storage system by way of the output interface to another location, and a power input connection region connectable to a power generating device separate from the hub, the arrangement being such that the hub is free from any electrical export cable to an on-shore location.
18. A method comprising producing a fuel source upon a standalone fuel-production hub, storing the fuel source in a fuel-storage system on the hub, the fuel storage system having input and output interfaces, discharging the fuel from the fuel-storage system by way of the output interface to another location, and importing power for the fuel-production hub from a power generating device separate from the hub and being connectable thereto, the hub being free from any electrical export cable to an on-shore location.