The invention relates to a method for providing electrical energy to a seagoing vessel, a shipping infrastructure, and a relay system for providing electrical energy to a seagoing vessel.

Known battery powered ships comprise an electrical propulsion system and a battery for storing the electrical energy.

SUMMARY OF THE INVENTION

A disadvantage of battery powered ships is that the battery takes up space on the ship. Especially with international and intercontinental trade, where the sailing distances between ports may amount to several of thousands of nautical miles, the required battery capacity and therewith the volume that the batteries occupy would be very high. The required batteries would reduce the transport capacity of the battery powered ships and would therefore reduce the economic feasibility of battery powered ships, especially for international and intercontinental trade. Therefore the deployment of battery powered ships has been limited to fixed shipping routes for inland shipping having relative small sailing distances between the ports. An example of such a shipping route is an electrified ferry service wherein battery powered ships shuttle between ports.

It is an object of the present invention to provide a method for providing electrical energy to a seagoing vessel, a shipping infrastructure, and a relay system for providing electrical energy to a seagoing vessel that makes battery powered vessels more suitable for long distance shipping.

According to a first aspect, the invention provides a method for providing energy, by means of a relay system, to a seagoing vessel that navigates a sailing route, wherein the seagoing vessel comprises a first electric propulsion system and a first power interface that is electrically connected to the first electric propulsion system, wherein the relay system comprises multiple charging hubs along and distributed over the sailing route, that have a second power interface that is electrically connected to an electrical energy source, and wherein the relay system comprises multiple charging vessels that have an accumulator for accumulating electrical energy and a third power interface that is electrically connected to the accumulator, wherein the third power interface and the first power interface are configured to connect to each other for electrically connecting the accumulator and the first electric propulsion system, and wherein the second power interface and the third power interface are configured to connect to each other for electrically connecting the electrical energy source and the accumulator, wherein each of the charging vessels is configured to work in a charge mode, a sail mode and a supply mode, wherein in the charge mode the third power interface is connected to the second power interface for charging the accumulator by the electrical energy source, wherein in the sail mode the charging vessel sails between one of the charging hubs and the seagoing vessel, and wherein in the supply mode the third power interface is connected to the first power interface for supplying electrical energy from the accumulator to the first electric propulsion system, wherein the method comprises; navigating a first seagoing vessel over the sailing route, at a first charging hub connecting the third power interface of a first charging vessel to the second power interface of the first charging hub, in the charge mode charging the accumulator of the first charging vessel by the electrical energy source of the first charging hub via the third power interface and the second power interface, disconnecting the third power interface and the second power interface, in the sail mode sailing the first charging vessel from the first charging hub to the first seagoing vessel, at the first seagoing vessel connecting the third power interface to the first power interface, in the supply mode supplying electrical energy from the accumulator of the first charging vessel to the first electric propulsion system of the first seagoing vessel via the third power interface and the first power interface while the first charging vessel sails with the first seagoing vessel along at least a part of the sailing route, and disconnecting the third power interface and first power interface.

Along the sailing route the seagoing vessel can be electrically connected to the charging vessel. While the charging vessel and the seagoing vessel are electrically connected, the accumulator supplies electrical energy to the first electric propulsion system to propel the seagoing vessel. The accumulator of the charging vessel therewith extends the sailing range of the seagoing vessel. The method for providing energy to a seagoing vessel therewith makes battery powered vessels more suitable for long distance shipping.

As the charging vessels can sail between the charging hubs and the seagoing vessels, the seagoing vessels can keep sailing along the sailing route while a sufficiently charged accumulator is electrically connected to the first electric propulsion system. The seagoing vessel does not have to call at a port or at a charging station to be charged. The method therewith increases the efficiency of supplying electric energy to the seagoing vessels as compared to conventional charging methods.

In an embodiment the charging vessels comprise a second electric propulsion system that is electrically connected to the accumulator, wherein in the sail mode, the sailing of the first charging vessel from the first charging hub to the first seagoing vessel comprises sailing the first charging vessel by means of the second electric propulsion system. The second electric propulsion system of the charging vessel may be largely integrated with the electrical systems of the charging vessel. This provides an efficient, lean and potentially sustainable propulsion system to the charging vessel.

In an embodiment the method comprises at a second charging hub connecting the third power interface of a second charging vessel to the second power interface of the second charging hub, in the charge mode charging the accumulator of the second charging vessel by the electrical energy source of the second charging hub via the third power interface and the second power interface, disconnecting the third power interface and the second power interface, in the sail mode sailing the second charging vessel from the second charging hub to the first seagoing vessel, at the first seagoing vessel connecting the third power interface to the first power interface, in the supply mode supplying electrical energy from the accumulator of the second charging vessel to the first electric propulsion system of the first seagoing vessel via the third power interface and the first power interface while the second charging vessel sails with the first seagoing vessel along at least a part of the sailing route, and disconnecting the third power interface and the first power interface. In an embodiment along at least a part of the sailing route the first electric propulsion system of the first seagoing vessel is supplied with electrical energy by the accumulator of successive charging vessels. The charging hubs and charging vessels of the relay system are distributed over the sailing route in such a way that a sufficiently charged accumulator is regularly available for the seagoing vessel along the sailing route. The relay system therewith extends the sailing range of the seagoing vessel even further.

In an embodiment after connecting the third power interface of the first charging vessel to the first power interface of the first seagoing vessel, at least two accumulators of respective charging vessels are electrically connected to the first electric propulsion system of the first seagoing vessel. Successive charging vessels are, for a short period, simultaneously connected to the seagoing vessel. In an embodiment thereof the at least two accumulators of respective charging vessels are electrically connected to the first electric propulsion system of the first seagoing vessel along maximum ten percent of the sailing route, preferably along maximum five percent of the sailing route. This method prevents a gap between the two supply periods of electrical energy to the seagoing vessel by the successive charging vessels and therefore prevents that the seagoing vessel temporarily is not supplied with electrical energy by a charging vessel.

In an embodiment the first seagoing vessel comprises an accumulator for supplying electrical energy to the first electric propulsion system, wherein the accumulator of the first seagoing vessel is electrically connected to the first power interface, and wherein in the supply mode, the supplying electrical energy from the accumulator of the first charging vessel to the first electric propulsion system of the first seagoing vessel comprises supplying electrical energy from the accumulator of the first charging vessel to the accumulator of the first seagoing vessel to charge the accumulator of the first seagoing vessel. In an embodiment thereof the method comprises supplying electrical energy from the accumulator of the first seagoing vessel to the first electric propulsion system of the first seagoing vessel while no accumulator of the charging vessels is electrically connected to the first electric propulsion system of the first seagoing vessel. In this way the accumulator of the first seagoing vessel can cover a gap between the two supply periods of electrical energy to the seagoing vessel by the successive charging vessels and therefore prevents that the seagoing vessel temporarily is not supplied with electrical energy. When the first seagoing vessel only comprises a battery-electric propulsion system, the charging vessel can fast-charge the accumulator of the first seagoing vessel in a relatively short period of time in order to increase the sailing range of said seagoing vessel. The seagoing vessel then may navigate the majority of the sailing route using the accumulator of the first seagoing vessel.

In an embodiment the second power interface and the first power interface are configured to connect to each other for electrically connecting the electrical energy source and the accumulator of the first seagoing vessel, wherein the method comprises at the first charging hub connecting the first power interface of the first seagoing vessel to the second power interface of the first charging hub to charge the accumulator of the first seagoing vessel. When the first seagoing vessel comprises an accumulator, the seagoing vessel can dock at the charging hub to charge the accumulator of the seagoing vessel. This may for instance be done when no charging vessels are available.

In an embodiment in the supply mode supplying electrical energy from the accumulator of the first charging vessel to the accumulator of the first seagoing vessel to charge the accumulator of the first seagoing vessel comprises charging the accumulator of the first seagoing vessel along maximum ten percent of the sailing route, preferably along maximum five percent of the sailing route. The accumulator of the seagoing vessel may be charged along a relative short section of the sailing route that is located close to a charging hub. Thereby the sailing distances of the charging vessels may be reduced whereby the charging vessels may operate in a more efficient manner.

In an embodiment the first seagoing vessel comprises a combustion engine, wherein navigating the first seagoing vessel over the sailing route comprises navigating the first seagoing vessel over the sailing route by means of the combustion engine while no accumulator of the charging vessels is electrically connected to the first electric propulsion system of the first seagoing vessel. The combustion engine may directly drive a propeller shaft of the first electric propulsion system to propel the seagoing vessel and to therewith sail the seagoing vessel over the sailing route. In an embodiment the combustion engine is configured to generate electrical energy, and wherein the method comprises supplying electrical energy from the combustion engine to the first electric propulsion system of the first seagoing vessel while no accumulator of the charging vessels is electrically connected to the first electric propulsion system of the first seagoing vessel. The combustion engine may either generate electrical energy for an electric motor of the first electric propulsion system or for the accumulator of the first electric propulsion system. The combustion engine may be used to cover the gap between the two supply periods of electrical energy to the seagoing vessel by the charging vessels. Or it may be used in locations that are not covered by the relay system.

In an embodiment the method comprises navigating a second seagoing vessel over the sailing route, in the sail mode sailing the first charging vessel from the first seagoing vessel to a subsequent second charging hub, at the second charging hub connecting the third power interface of the first charging vessel to the second power interface of the second charging hub, in the charge mode charging the accumulator of the first charging vessel by the electrical energy source via the third power interface and the second power interface, disconnecting the third power interface and the second power interface, in the sail mode sailing the first charging vessel from the second charging hub to the second seagoing vessel, at the second seagoing vessel connecting the third power interface to the first power interface, in the supply mode supplying electrical energy from the accumulator of the first charging vessel to the first electric propulsion system of the second seagoing vessel via the third power interface and the first power interface while the first charging vessel sails with the second seagoing vessel along at least a part of the sailing route, and disconnecting the third power interface and the first power interface. In an embodiment the accumulator of the first charging vessel successively supplies electrical energy to the first electric propulsion system of successive seagoing vessels. By having a supply vessel supplying electrical energy to several successive seagoing vessels and by having the charging vessels charged at various charging hubs the relay system can be used in a more efficient way.

In an embodiment the second power interface of the charging hub is electrically connected to the electrical energy source through a smart grid, wherein in the charge mode the third power interface is connected to the second power interface for charging and discharging the accumulator, and wherein the method comprises in the charge mode discharging the accumulator of the first charging vessel via the third power interface and the second power interface. The accumulator can be used to temporarily store an excess of generated electrical energy and to return it to the smart grid at a later point in time. In this way supply and demand of electrical energy in the smart grid can be better matched to each other.

According to a second aspect, the invention provides a method for providing energy, by means of a relay system, to a seagoing vessel that navigates a sailing route, wherein the relay system comprises multiple charging hubs along and distributed over the sailing route and multiple charging vessels, wherein each of the charging vessels is configured to work in a charge mode in which the charging vessel is connected to the charge hub, a sail mode in which the charging vessel sails between one of the charging hubs and the seagoing vessel and a supply mode in which the charging vessel is connected to the seagoing vessel, and wherein the method comprises; navigating a first seagoing vessel over the sailing route, at a first charging hub charging the first charging vessel, sailing the first charging vessel from the first charging hub to the first seagoing vessel, at the first seagoing vessel supplying electrical energy from the first charging vessel to the first seagoing vessel while the first charging vessel sails with the first seagoing vessel along at least a part of the sailing route.

According to a third aspect, the invention provides a shipping infrastructure that comprises a seagoing vessel that navigates a sailing route, and a relay system for providing energy to the seagoing vessel, wherein the seagoing vessel comprises a first electric propulsion system and a first power interface that is electrically connected to the first electric propulsion system, wherein the relay system comprises multiple charging hubs along and distributed over the sailing route, that have a second power interface that is electrically connected to an electrical energy source, and wherein the relay system comprises multiple charging vessels that have an accumulator for accumulating electrical energy and a third power interface that is electrically connected to the accumulator, wherein the third power interface and the first power interface are configured to connect to each other for electrically connecting the accumulator and the first electric propulsion system, and wherein the second power interface and the third power interface are configured to connect to each other for electrically connecting the electrical energy source and the accumulator, wherein each of the charging vessels is configured to work in a charge mode, a sail mode and a supply mode, wherein in the charge mode the third power interface is connected to the second power interface for charging the accumulator by the electrical energy source, wherein in the sail mode the charging vessel sails between one of the charging hubs and the seagoing vessel, and wherein in the supply mode the third power interface is connected to the first power interface for supplying electrical energy from the accumulator to the first electric propulsion system.

The shipping infrastructure and its embodiments relate to the practical implementation of the method according to any one of the aforementioned embodiments and thus have the same technical advantages, which will not be repeated hereafter.

According to a fourth aspect, the invention provides a relay system for providing energy to a seagoing vessel that comprises a first electric propulsion system and a first power interface that is electrically connected to the first electric propulsion system, wherein the relay system comprises multiple charging hubs along and distributed over a sailing route, that have a second power interface that is electrically connected to an electrical energy source, and wherein the relay system comprises multiple charging vessels that have an accumulator for accumulating electrical energy and a third power interface that is electrically connected to the accumulator, wherein the third power interface and the first power interface are configured to connect to each other for electrically connecting the accumulator and the first electric propulsion system, and wherein the second power interface and the third power interface are configured to connect to each other for electrically connecting the electrical energy source and the accumulator, wherein each of the charging vessels is configured to work in a charge mode, a sail mode and a supply mode, wherein in the charge mode the third power interface is connected to the second power interface for charging the accumulator by the electrical energy source, wherein in the sail mode the charging vessel sails between one of the charging hubs and the seagoing vessel, and wherein in the supply mode the third power interface is connected to the first power interface for supplying electrical energy from the accumulator to the first electric propulsion system. The various aspects and features described and shown in the specification can be applied, individually, wherever possible. These individual aspects, in particular the aspects and features described in the attached dependent claims, can be made subject of divisional patent applications.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be elucidated on the basis of an exemplary embodiment shown in the attached drawings, in which:

Figure 1 is an isometric view of a shipping infrastructure according to an embodiment of the invention; Figure 2A is a side view of a charging hub of the shipping infrastructure of figure 1;

Figures 2B and 2C respectively are a side view and a section view transverse to the side view of a catcher of the charging hub of figure 2A; Figure 3 is an isometric view of a charging vessel of the shipping infrastructure that is connected to a seagoing vessel of the shipping infrastructure; and

Figure 4 is a schematic top view of the shipping infrastructure. DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 4 show a shipping infrastructure 1 according to an embodiment of the invention that comprises one or more seagoing vessels 10 that navigate along a sailing route 2, and a relay system 15 for providing electrical energy to the seagoing vessels 10. The relay system 15 comprises one or more charging hubs 20 along the sailing route 2, and multiple charging vessels 50 that transfer between the charging hubs 20 and the seagoing vessels 10.

The sailing route 2 extends between two or more seaports and may pass through remote areas of the world seas and oceans. The seagoing vessels 10 transport goods or passengers between the seaports over long distances of at least 50 nautical miles up to several of thousands of nautical miles. For instance, a main container liner route between Asia and North Europe extends over approximately 12000 nautical miles, along the African coast. Containers are transported along this route by very large container ships. The containers are transferred between the very large container ships and medium-size feeder ships that transport the containers between smaller ports within the continent.

The seagoing vessels 10 comprise a not shown main first electric propulsion system to propel or move the seagoing vessels 10 along at least a part of the sailing route 2. The seagoing vessels 10 comprise a first power interface 11 that is electrically connected to the first electric propulsion system. The seagoing vessel 10 may comprise a not shown accumulator or battery for storing and providing the electrical energy that is used by the first electric propulsion system. The battery of the seagoing vessel 10 is electrically connected to the first propulsion system and to the first power interface 11.

The charging hubs 20 are located along and distributed over the sailing route 2. The charging hubs 20 are each electrically connected to an electrical energy source, and have a second power interface 36 that is electrically connected to the electrical energy source.

The charging vessels 50 have a not shown internal accumulator for accumulating electrical energy and third power interfaces 52 that are electrically connected to the accumulator.

Figure 1 only shows a first seagoing vessel 10, a first charging hub 20, and a first, a second and a third charging vessel 50. The rest of the seagoing vessels 10, the charging hubs 20 and the charging vessels 50 are located further along the sailing route 2. In the text hereafter the seagoing vessels 10, the charging hubs 20, and the charging vessels 50 may be described in the singular form but it is to be understood that the description applies to all the seagoing vessels 10, charging hubs 20, and charging vessels 50 of the shipping infrastructure 1.

As best shown in figure 3, the charging vessel 50 comprises an elongate floating hull 51 having a port side and a starboard side, the third power interfaces 52 at both the port side and the starboard side of the hull 51, navigation and communication equipment 53 on the hull 51, and solar panels 54 on the hull 51 to charge the accumulator. The accumulator is configured to store or accumulate electrical energy. Preferably the accumulator is an electrical battery but any type of multi cycle electrical energy storage systems may be applied. The charging vessel 50 comprises a not shown second electric propulsion system to propel or move the charging vessels 50. The second electric propulsion system is electrically connected to its accumulator and/or to its solar panels 54. The charging vessel 50 may be operated by a naval crew, it may be remotely controlled, or it may sail autonomously or semi-autonomously.

The first power interface 11 of the seagoing vessel 10 corresponds to the third power interface 52 of the charging vessel 50. The third power interface 52 of the charging vessel 50 and the first power interface 11 of the seagoing vessel 10 are configured to electrically connect the accumulator of the charging vessel 50 and the first electric propulsion system of the seagoing vessel 10. In this example the first power interface 11 and the third power interface 52 are configured to connect to each other to transfer electrical energy between the charging vessel 50 and the seagoing vessel 10, more specifically electrical energy is supplied from the accumulator of the charging vessel 50 to the first electric propulsion system of the seagoing vessel 10. The electrical energy may be wirelessly transferred or transmitted by for instance inductive coupling or capacitive coupling. It is to be understood that alternatively the first power interface 11 and the third power interface 52 may comprise a wired connection using plugs and sockets that are engageable with each other to electrically connect the accumulator and the first electric propulsion system to transfer electrical energy between the accumulator of the charging vessel 50 and the first electric propulsion system of the seagoing vessel 10.

As best shown in figure 2A, the charging hub 20 in this example comprises a support structure 29 having a buoyant body 21 below the water surface 3 and two vertical columns 22 that pass through the water surface 3 and that are supported by the buoyant body 21 at the bottom ends 23 thereof. The charging hub 20 comprises a housing 25 above the water surface 3 that is supported by the columns 22 at the top ends 24 thereof, and two catchers 30 for the charging vessels 50 at the water surface 3 that are supported by the columns 22. The support structure 29 of the charging hub 20 is connected to the seabed 4 by taut cables 26 that are connected to anchors 27. The taut cables 26 keep the buoyant body 21 spaced apart from the seabed 4 over a fixed distance. Alternatively the support structure 29 of the charging hub 20 may be a monopile, a jacket or any other suitable offshore support structure.

The charging hub 20 is electrically connected to the electrical energy source by a power cable 6. The electrical energy source preferably is a renewable energy source that is located close to the charging hub 20 such as an offshore wind turbine 5, an offshore wind farm, a floating solar energy system or any kind of offshore power plant. The electrical energy sources may already be present along the shipping route 2 making it relatively easy to integrate them into the shipping infrastructure 1. The electrical energy sources can also be installed along with the charging hubs 20 as part of the rollout of the shipping infrastructure 1. Renewable electrical energy sources are well suited to provide the charging hubs 20 with electrical energy in remote areas of the shipping route 2 . Alternatively the charging hub 20 is electrically connected to a power grid that is connected to shore and which may be connected to any kind of onshore power plant. One or more wind turbines and/or solar energy systems may be integrated in the charging hub 20.

The electrical energy source and the charging hub 20 with the charging vessel 50 may be interconnected through or may be integrated in a smart grid. The accumulator of the charging vessel 50 may then be charged when the supply of electrical energy is high and/or the demand thereof is low to temporarily store electric energy, and be discharged to return the electric energy from the accumulator to the smart grid when the supply thereof is low and/or the demand thereof is high. In this way supply and demand of electrical energy in the smart grid can be better matched to each other. As the storage capacity for electrical energy of the accumulator of the charging vessels 51 is relatively large, said accumulators may be very suitable to be used in the smart grid.

As best shown in figures 2B and 2C, in this example the charging hubs 20 comprise two parallel catchers 30 that have an elongate cylindrical cage 31 that defines a through channel 32 for the charging vessel 50 and that has flared ends for guiding the charging vessel 50 into the channel 32. The catchers 30 are connected to the support structure 29 and are spaced apart from each other by an intermediate frame 28. Each cage 31 comprises parallel vertical steel tubular rings 33 that are spaced apart from each other by horizontal steel tubular girders 34. Each catcher 30 comprises two elongate bumpers 35 that are connected to the cage 31 within and along the length of the channel 32 and that are positioned at opposite sides of the cage 31 near the bottom thereof. The bumpers 35 guide, stabilize or support the charging vessel 50 that enters or is docked in the cage 31.

The catcher 30 comprises the second power interface 36 that corresponds to the third power interface 52 of the charging vessels 50. The second power interface 36 is attached to the side of the cage 31 inside the channel 32 halfway the length thereof. The second power interface 36 comprises two extendable rods 37, an abutment plate 38 at the free end of each extendable rod 37, and a hydraulic cylinder 39 between each extendable rod 37 and the cage 31 for extending and retracting the extendable rods 37. The second power interface 36 of the charging hub 20 and the third power interface 52 of the charging vessel 50 are configured to electrically connect the electrical energy source of the charging hub 20 and the accumulator of the charging vessel 50. To electrically connect the charging hub 20 and the charging vessel 50 the extendable rods 37 extend towards the charging vessel 50 until the abutment plates 38 are in abutment with the third power interface 52.

In this example the second power interface 36 and the third power interface 52 are configured to connect to each other to transfer electrical energy between the charging hub 20 and the charging vessel 50, more specifically electrical energy is supplied from the electrical energy source of the charging hub 20 to the accumulator of the charging vessel 50 to charge the accumulator. The electrical energy may be wirelessly transferred or transmitted by for instance inductive coupling or capacitive coupling. It is to be understood that alternatively the second power interface 36 and the third power interface 52 may comprise a wired connection using plugs and sockets that are engageable with each other to electrically connect the electrical energy source and the accumulator to transfer electrical energy between the electrical energy source of the charging hub 20 and the accumulator of the charging vessel 50.

The seagoing vessel 10 can also be charged directly at the charging hub 20. The second power interface 36 and the first power interface 11 are therefore configured to connect to each other to transfer electrical energy between the charging hub 20 and the seagoing vessel 10, more specifically electrical energy is supplied from the electrical energy source of the charging hub 20 to the battery of the seagoing vessel 10 to charge the battery of the seagoing vessel 10.

As best shown in figure 4, in use the relay system 15 of the shipping infrastructure 1 provides electrical energy to the seagoing vessel 10 that navigates the sailing route 2 by successively electrically connecting charging vessels 50, that were electrically charged at a charging hub 20, to the seagoing vessel 10. Therefore each of the charging vessels 50 is configured to work in a charge mode, a sail mode and a supply mode, which will be explained in more detail hereafter. The sailing route 2 is defined as the route that is navigated by a seagoing vessel 10 between a starting point and an endpoint of a shipping voyage of the seagoing vessel. The starting point and the endpoint usually are seaports but may also be, for instance, an anchor place, an offshore platform or a shipyard.

In the charge mode of the charging vessel 10, the charging vessel 10 is docked at the charging hub 20 in the catcher 30 thereof. The charging vessel 50 is electrically connected to the charging hub 20 through or via the third power interface 52 of the charging vessel 50 and the second power interface 36 of the charging hub 20. The accumulator of the charging vessel 50 is being charged by the charging hub 20 or the accumulator is sufficiently charged and the charging vessel 50 is standby for a passing seagoing vessel 10. When the charging hub is connected to the smart grid, in the charging mode the charging vessel 10 is configured to discharge the accumulator to supply or return electrical energy to the smart grid. The accumulator functions as a temporary storage of electrical energy.

When a seagoing vessel 10 that navigates the sailing route 2 approaches or passes the charging hub 20 the sufficiently charged charging vessel 50 is switched to the sail mode in which it sails from the charging hub 20 to the passing seagoing vessel 10 along a first sailing section A of the charging vessel 50. At the seagoing vessel 10 the charging vessel 50 sails closely alongside or in abutment with the seagoing vessel 10. Alternatively the sufficiently charged charging vessel 50 in the sail mode sails from the charging hub 20 to the sailing route 2. At or near the sailing route 2 the charging vessel 50 awaits the passing of the seagoing vessel 10 or it sails towards an approaching seagoing vessel 10.

Subsequently the charging vessel 50 is switched to the charge mode in which the charging vessel 50 is electrically connected to the seagoing vessel 10 through or via the third power interface 52 of the charging vessel 50 and the first power interface 11 of the seagoing vessel 10. The charging vessel 50 supplies electrical energy from the accumulator to the first electric propulsion system of the seagoing vessel 10. Alternatively the charging vessel 50 supplies electrical energy from the accumulator to the optional battery of the seagoing vessel 10 to charge the battery of the seagoing vessel 10. In the charging mode the charging vessel 50 sails together with the seagoing vessel 10 along at least a part of the sailing route 2, along a second sailing section B of the charging vessel 50.

When the remaining electric capacity of the accumulator of the charging vessel 50 reaches a predetermined lower limit or when the battery of the seagoing vessel 10 is sufficiently charged, the charging vessel 50 electrically disconnects from the seagoing vessel 10 and is switched to the sail mode. In the sail mode the charging vessel 50 sails from the passing seagoing vessel 10 to a subsequent charging hub 20, along a third sailing section C of the charging vessel 50. The subsequent charging hub 20 may be any charging hub 20 of the shipping infrastructure 1. For instance, the subsequent charging hub 20 is the first next charging hub 20 along the sailing route 2 of the seagoing vessel 10 after the charging hub 20 at which the charging vessel 50 was previously charged. Alternatively the charging vessel 50 returns to the same charging hub 20 as it was previously charged at, wherein the charging vessel 50 may be dedicated to the specific charging hub 20.

The predetermined lower limit of the remaining electric capacity of the accumulator may be based on the sailing distance for the charging vessel 50 between the passing seagoing vessel 10 and the subsequent charging hub 20. The remaining electric capacity of the accumulator needs to be sufficient for the charging vessel 50 to reach the subsequent charging hub 20. Alternatively the charging vessel 50 electrically disconnects from the seagoing vessel 10 and is switched to the sail mode when the accumulator of the charging vessel 50 is fully discharged. The charging vessel 50 then sails to the subsequent charging hub 20 while it is energized by the solar panels 54.

At the charging hub 20 the charging vessel 50 sails into the channel 32 of the catcher 30. The bumpers 35 may guide the charging vessel 50 to its docking position in which the third power interface 52 of the charging vessel 50 is aligned with the second power interface 36 of the charging hub 20. The hydraulic cylinders 39 extend the extendable rods 37 towards the charging vessel 50 until the abutment plates 38 are in abutment with the third power interface 52 to electrically connect the second power interface 36 to the third power interface 52. The accumulator of the charging vessel 50 is then recharged by the charging hub 20 until it is sufficiently charged again.

During docking of the charging vessel 50 in the catcher 30 the hydraulic cylinders 39 keep the abutment plates 38 in abutment with the third power interface 52 by applying a constant pressure while allowing the charging vessel 50 and therewith the third power interface 52 to move, for instance due to waves and wind. During docking of the charging vessel 50 in the catcher 30 the second power interface 36 may be used to dampen the wave and wind induced motions of the charging vessel 50. The hydraulic cylinders 39 of the second power interface 36 may dampen or constrain the motions of the charging vessel 50 by constraining or damping the displacement of the rod of the hydraulic cylinders 39.

As best shown in figure 4, the relay system comprises multiple charging vessels 50 and multiple charging hubs 20 along the sailing route 2. The passing seagoing vessel 10 can be successively supplied with electrical energy by successive charging vessels 10. Therefore a first charging vessel 50 is charged at a first charging hub 20, sails to a first seagoing vessel 10 and supplies the first electrical propulsion system of the first seagoing vessel 10 with electrical energy. A second charging vessel 10 that was charged at a second charging hub 10 sails to the first seagoing vessel 10. After supplying the first seagoing vessel 10 with electrical energy, the first charging vessel 50 is electrically disconnected from the first seagoing vessel 10 and the second charging vessel 10 is electrically connected to the first seagoing vessel 10. The electrically disconnecting the first charging vessel 50 and electrically connecting the second charging vessel 50 can be carried out in different sequences as is explained in more detail hereafter.

To ensure continuous electric propulsion of the seagoing vessel 10, the seagoing vessel 10 may comprise two or more first power interfaces 11 so that two or more charging vessels 50 may be electrically connected to the seagoing vessel 10 at the same time. In this manner successive charging vessels 50 are temporarily simultaneously electrically connected to the seagoing vessel 10 to, within the simultaneous electrical connection period, switch the first electric propulsion system between the electrically connected charging vessels 50. The simultaneous electrical connection period of the charging vessels 10 may be kept as small as possible. The at least two charging vessels 50 are therefore electrically connected to the seagoing vessel 10 along maximum ten percent of the sailing route 2 that is covered by the seagoing vessel 10, preferably along maximum 5 percent of the sailing route, more preferably along maximum 2 percent of the sailing route.

Alternatively the continuous electric propulsion of the seagoing vessel 10 is ensured by the optional battery of the seagoing vessel 10. The charging vessels 50 are then electrically connected to the seagoing vessel 10 one after the other. In the period between the electrical connection of two successive charging vessels 50 the battery of the seagoing vessel 10 provides electrical energy to the first electric propulsion system. When the charging vessels 50 are electrically connected to the seagoing vessel 10, the battery of the seagoing vessel 10 can be charged by the accumulator of the charging vessel 50. The charging vessels 50 can be electrically connected to the seagoing vessel 10 along a relatively short section of the sailing route 2 near a charging hub 20 to fast- charge the battery of the seagoing vessel 10. The charging vessels 50 may be electrically connected to the seagoing vessel 10 along maximum ten percent of the sailing route, preferably along maximum five percent of the sailing route.

Alternatively the first electric propulsion system of the seagoing vessel 10 comprises a combustion engine to ensure the continuous propulsion of the seagoing vessel 10. The combustion engine is connected to and drives an electric generator to either generate electrical energy for and supply electrical energy to an electric motor of the first electric propulsion system or the battery of the first seagoing vessel 10. Alternatively the combustion engine may directly drive a propeller shaft of the first electric propulsion system to propel the seagoing vessel 10 and to therewith sail the seagoing vessel 10 over the sailing route 2. The charging vessels 50 are electrically connected to the seagoing vessel 10 one after the other. In the period between the electrical connection of two successive charging vessels 50 the combustion engine of the seagoing vessel 10 provides propulsion to the seagoing vessel 10. This alternative may be favorable when existing seagoing vessels 10 are adjusted to fit in the shipping infrastructure 1. Vessels with a diesel-electric transmission or a hybrid electric transmission may be suitable for conversion. The existing seagoing vessels can therefore be retrofitted with a first power interface 11 and optionally with an electric motor. The original combustion engine of the existing seagoing vessel 10 may then be used to ensure the continuous propulsion of the seagoing vessel 10.

As best shown in figure 4, multiple seagoing vessels 10 may navigate along the sailing route 2 at the same time. The seagoing vessels 10 pass the subsequent charging hubs 20 one after the other. One charging vessel 50 may successively supply electrical energy to the first electric propulsion system of the successively passing seagoing vessels 10. Therefore a first charging vessel 50 is charged at a first charging hub 20, sails to a first seagoing vessel 10 and supplies the first electric propulsion system of the first seagoing vessel 10 with electrical energy. After supplying the first seagoing vessel 10 with electrical energy, the first charging vessel 50 sails to a subsequent charging hub 20. At the charging hub 20 the first charging vessel 50 docks in the catcher 30 for the accumulator to be charged. When the accumulator is sufficiently charged the first charging vessel sails to a second seagoing vessel 10 and supplies the first electrical propulsion system of the second seagoing vessel 10 with electrical energy. After supplying the second seagoing vessel 10 with electrical energy, the first charging vessel 50 sails to a subsequent charging hub 20. This routine may be repeated endlessly. It is to understood that the successive passing seagoing vessels 10 may navigate in two directions along the sailing route 2 and that the first charging vessel 50 may be charged at any one of the charging hubs 20. Any one of the charging hubs 20 may be the subsequent charging hub 20.

When the seagoing vessel 10 comprises a battery the seagoing vessel 10 may also dock at the charging hub 20 to recharge the battery of the seagoing vessel 10. The charging hubs 20 are then used as charging stations at sea and the seagoing vessels 10 sail from charging hub 20 to charging hub 20 along the sailing route 2.

It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention. From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention.