NL2017797B1 - Offshore system for converting energy, and method for the assembly and use of such an offshore system - Google Patents

Abstract

An offshore system for converting energy comprises: at least one energy convertor 2 for converting renewable energy into electrical energy, a renewable liquid fuel synthesis plant 4 comprising at least an electrical connection 6 with the energy convertor 2 and an inlet 8 for sea water 10, an offloading device 12 for transferring the renewable liquid fuel to a vehicle 14 and/or a pipeline, and a foundation 16 which in an operative state of the offshore system 1 rests on a sea bed 18 and supports the renewable liquid fuel synthesis plant 4.

Description

Patent center

The Netherlands

NL BI 2017797

(21) Request number: 2017797 © Request submitted: 11/16/2016

Θ 2017797

BI PATENT @ Int. CL:

F03D 13/25 (2017.01) F03D 9/19 (2017.01)

(T) Application registered: (73) Patent holder (s): 25/05/2018 SEANOVATIONS IPA B.V. in Rotterdam. (43) Application published: - (72) Inventor (s): Reindert Roelf van Genderen in Rotterdam. (47) Patent granted: 25/05/2018 (74) Agent: (45) Patent issued: No. 11/06/2018

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Offshore system for converting energy, and method for the assembly and use of system

An offshore system for converting energy comprises: at least one energy converter 2 for converting renewable energy into electrical energy, a renewable liquid fuel synthesis plant 4 including at least an electrical connection 6 with the energy converter 2 and an inlet 8 for sea water 10, an offloading device 12 for transferring the renewable liquid fuel to a vehicle 14 and / or a pipeline, and a foundation 16 which in an operative state of the offshore system 1 rests on a sea bed 18 and supports the renewable liquid fuel synthesis plant 4.

such an offshore

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent corresponds to the documents originally submitted.

Title: Offshore system for converting energy, and method for the assembly and use of such an offshore system

The invention relates to an offshore system for converting energy, according to the preamble of claim 1.

An offshore system of this type is used for production or renewable liquid fuel. Electrical energy from a renewable source, such as an offshore wind farm, is used to produce the renewable liquid fuel from seawater and CO2 (carbon dioxide).

An offshore system or this type is known from DE-102007019027-A1. This document discloses a ship which is towed by kites and uses turbines driven by its forward speed to transform wind energy into electrical energy. A subsequent electrolysis of water by the obtained electrical energy produces hydrogen. A synthesis of methanol is obtained by the reaction of hydrogen with carbon dioxide.

A disadvantage of the known system is that it has considerable downtime and is not sufficiently reliable.

The invention aims to solve at least one of these problems, or at least to provide an alternative. In particular, the invention aims to provide an offshore system with a high productivity.

This aim is achieved by an offshore system according to claim 1. Preferred are defined in the dependent claims.

An offshore system for converting energy comprises:

at least one energy converter for converting renewable energy into electrical energy, a renewable liquid fuel synthesis plant including at least an electrical connection with the energy converter and an inlet for sea water, an offloading device for transferring the renewable liquid fuel to a vehicle and / or a pipeline, and a foundation which in an operative state of the offshore system rests on a sea bed and supports the renewable liquid fuel synthesis plant.

The foundation on the sea bed provides a stable platform for the renewable liquid fuel synthesis plant, independent from weather and wave conditions. This allows the renewable liquid fuel synthesis plant to produce with a low downtime. In contrast, the renewable liquid fuel synthesis plant on the ship of the prior art document is in constant motion due to waves and wind. These motions affect the renewable liquid fuel synthesis plant, causing breakdown or motion sensitive components and a necessity to shut down the synthesis when the motions come above a critical level. Both effects limit cause a considerable downtime or the prior art system, which is alleviated by the current invention.

In an embodiment, the foundation is made of concrete. A concrete foundation is corrosion resistant, both with respect to sea water and to liquid fuels.

In an embodiment, the foundation is a gravity based foundation or a former fossil fuel production platform. This foundation type is called a gravity based structure, because it maintains its position on top of the seabed by virtue of its huge mass and inertia, without the need for piling. Many offshore oil and gas fields have been depleted and are at the end of their productive life. The large offshore production platforms located on those fields are decommissioned. The owner of offshore production installations is legally obliged to completely remove them after decommissioning. This is technically very challenging and very costly. The concrete foundations have a technical lifetime far beyond the productive lifespan of the oil or gas reservoir they serve. Aw, re-using existing foundations not only saves cost of a new offshore foundation, but more importantly makes a costly and risky reverse installation and onshore demolition of the concrete platform unnecessary. Large additional cost savings can be obtained by modification, rather than removal, or the existing topside. A further cost saving is possible because the complicated internal cleaning of the substructure tanks will not be required, as any remaining oily deposit in those tanks will dissolve over time in the renewable liquid fuels, it will amount to a harmless trace ingredient.

An embodiment further comprises at least one storage tank for malfunctioning produced renewable liquid fuel. This allows the temporary storage of renewable liquid fuel, e.g. to enable a tanker to load fully in a short time.

In an embodiment, the least one storage tank is provided under water. An underwater storage tank weighs less than a tank above water and thus requires less supporting structures.

In an embodiment, the least one storage tank is provided in the foundation. This provides a compact and economical solution. In particular, the foundation is a gravity based foundation or a former fossil fuel production platform. Such a foundation already comprises storage tanks which are re-used for disrupting renewable liquid fuels produced according to the invention.

In an embodiment, the least one renewable energy converter is one of the list: a wind energy converter, a wave energy converter, an ocean thermal energy conversion plant, an ocean current energy converter, a tidal current energy converter, a solar power plant , a geothermal power plant. Each type of renewable energy converters has its own advantages and may be better suited for a specific location than another type. In particular in combination with the re-use of an existing former fossil fuel production platform, this means that the types of renewable energy converters which are best suited for the conditions in the vicinity of the existing platform can be chosen.

In an embodiment, the least one renewable energy converter is a floating wind turbine. Over the past two decades a large number of offshore wind farms has been built in near-coastal zones in Europe, using bottom-founded wind turbines. Maximum water deposits or such wind farm locations are around 45 meters. Several designs for floating wind turbines have been developed, with some prototypes successfully installed offshore. Independent research has found that the required investment cost for a wind farm with floating wind turbines will be comparable to a wind farm with traditional bottom founded structures. Using floating wind turbines thus increasing the number of potential offshore locations. Thanks for the renewable liquid fuel synthesis plant on a foundation of the current invention, no cables are required to transport electricity from these remote deep water locations to the shore.

In an embodiment, the renewable liquid fuel synthesis plant comprises an H2 module for the production of H2, in particular by electrolysis or sea water.

In an embodiment, the renewable liquid fuel synthesis plant comprises a CO2 module for the sequestration of CO2 from the atmosphere or seawater.

In an embodiment, the renewable liquid fuel synthesis plant comprises a hydrocarbon synthesis module for the production of one or more hydrocarbons from H2 and CO2.

In an embodiment, the renewable liquid fuel synthesis plant comprises an alcohol module for the production of ethanol, methanol, or butanol, in particular from H2 and CO2.

In an embodiment, the renewable liquid fuel synthesis plant comprises a water treatment module for the treatment and purification of seawater.

The invention further relates to a method for the assembly of an offshore system, according to claim 10. Preferred are defined in the dependent claims.

A method for the assembly of an offshore system for converting energy according to any one or more of the above described, comprises the steps:

providing the foundation on the sea bed, positioning the renewable liquid fuel synthesis plant on the foundation, electrically connecting the at least one energy converter with the renewable liquid fuel synthesis plant, fluidly connecting the inlet with the sea, and fluidly connecting the renewable liquid fuel synthesis plant with the offloading device.

Such a method results in an offshore system for converting energy according to the invention, with the advantageous as described above.

In an embodiment, the step of providing the foundation comprises selecting an existing offshore production platform, and the step of positioning the renewable liquid fuel synthesis plant comprises the positioning of the renewable liquid fuel synthesis plant on the existing offshore production platform. Re-using existing foundations not only saves cost of a new offshore foundation, but more importantly makes a costly (and in particular in case of gravity based structure also risky) reverse installation and onshore demolition of the existing platform unnecessary. A further cost saving is possible because the complicated internal cleaning of the substructure tanks will not be required, as any remaining oily deposit in those tanks will dissolve over time in renewable liquid fuels, it will amount to a harmless trace ingredient.

An embodiment of the method further comprises the step of removing fossil fuel production equipment from the existing offshore production platform. This removal makes space for the renewable liquid fuel synthesis plant.

An embodiment of the method further comprises the step of refitting an existing topside or the existing offshore production platform. Modification, rather than removal, or the existing topside results in large additional cost savings.

In particular, part of the existing modules are removed, while others are refitted.

An embodiment of the method further comprises the step of providing at least one storage tank in fluid connection with the renewable liquid fuel synthesis plant and the offloading device. This allows the temporary storage of renewable liquid fuel, e.g. to enable a tanker to load fully in a short time.

In an embodiment, the least one storage tank is an existing storage tank or an existing offshore production platform. Re-using an existing storage tank results in considerable cost savings, because no new tanks need to be made and the internal cleaning of the existing substructure tanks will not be required, as any remaining oily deposit in those tanks will dissolve in time in renewable liquid fuel, it will amount to a harmless trace ingredient.

The invention further relates to the use of an offshore system for converting energy, for the production of renewable liquid fuel from seawater and CO2, as defined in claim 16.

The invention, its effects, and advantages will be explained in more detail on the basis of the schematic drawing, in which:

FIG. 1 shows a first embodiment of an offshore system for converting energy according to the invention;

FIG. 2 shows a second embodiment of an offshore system for converting energy according to the invention;

FIG. 3 shows the first embodiment while offloading renewable liquid fuel;

FIG. 4 shows an existing concrete gravity based fossil fuel production platform;

FIG. 5 shows the removing of existing equipment from the fossil fuel production platform or fig. 4;

FIG. 6 shows the fossil fuel production platform or fig. 4 without the oil and / or gas production related equipment; and

FIG. 7 show the installation of a renewable liquid fuel synthesis plant on the former fossil fuel production platform or fig. 4.

The figures show an offshore system for converting energy according to the invention, which is denoted in its entirety by reference number 1. The offshore system 1 of the first edition (fig. 1) comprises a wind park with multiple energy converters in the form of wind turbines 2 for converting wind energy into electrical energy. The offshore system 1 further comprises a renewable liquid fuel synthesis plant 4. An electrical connection in the form of sub-sea cables 6 connects the renewable liquid fuel synthesis plant 4 with the energy converters 2. An inlet 8 is provided for the intake of sea water 10. The offshore system 1 further comprises an offloading device 12 for transferring the renewable liquid fuel to a vehicle, in this embodiment a tanker 14 (fig. 3).

The offshore system 1 comprises a foundation 16 which is shown in the shown operative state of the offshore system 1 rests on a sea bed 18 and supports the renewable liquid fuel synthesis plant 4. The foundation 16 of this edition is a concrete gravity based foundation 16 of a former fossil fuel production platform 100, as will be explained in more detail below. The offshore system 1 or this embodiment further comprises an accommodation 19, which is positioned on the foundation 16 as well, and a variety of storage tanks 20 for the renewable renewable fuel produced. The storage tanks 20 are connected to the renewable liquid fuel synthesis plant 4 via a pipe 21 and are provided under water, in the foundation 16.

Thanks to the foundation 16, there are no wave motions affecting the renewable liquid fuel synthesis plant 4, which would cause breakdown or motion sensitive components and a necessity to shut down the synthesis when the motions come above a critical level. Awesome, the current invention has less downtime than existing floating systems. Another advantage of a static foundation for the renewable liquid fuel synthesis plant is that it allows a large-scale production of renewable fuels by connecting a large number of energy converters to the plant.

Figure 2 shows a second embodiment of an offshore system 1 according to the invention, which is similar to that of Figure 1. Elements which are the same or similar will be denoted with the same reference number, and not explained again. The offshore system 1 or this embodiment comprises two energy converters: a wave energy converter 22 and a floating wind turbine 24.

The renewable liquid fuel synthesis plant or both includes several modules, which are not shown in detail. There are several possible pathways to synthesize

H2O and CO2 to hydrocarbon fuels and / or alcohol fuels, and the technology is still developing further. The present Embodiment uses the known Fischer-Tropsch process, dating from the early 20 ^th century. The common path to renewable fuels contains the following steps:

capturing CO2 from atmosphere or seawater dissociation or H2O into H2 and O2 hydrogenation or CO2 to a hydrocarbon or alcohol.

In an alternative embodiment, direct one-step conversion or CO2 from air into hydrocarbons or alcohols using advanced catalysts is applied.

In this embodiment, a first module is an H2 module for the production of H2 by electrolysis or purified sea water using electric energy. The renewable liquid fuel synthesis plant further comprises a CO2 module for capturing or CO2 from the seawater using CO2 sorbents, which sorbents are subsequently regenerated. In this embodiment, a methanol module is used for the hydrogenation of the CO2 produced using the H2 produced. The renewable liquid fuel synthesis plant further comprises a water treatment module for the treatment and purification of the seawater used in the H2 module.

In use, electric energy is generated by the wind turbines 2, 24 and / or the wave energy converter 22. This electrical energy is transported by the sub-sea cables 6 to the renewable liquid fuel synthesis plant 4. Sea water 10 is pumped with a water pump (not shown) to the renewable liquid fuel synthesis plant 4 via the inlet 8. The sea water is filtered in the water treatment module and further enters the H2 module, where H2 is produced via electrolysis. The CO2 module sequestrates CO2 from the seawater. The H2 and CO2 are fed into the methanol module for the production of methanol. The methanol is led into the storage tanks 20. When a tanker 14 arrives, the methanol is pumped from the storage tanks 20, through the offloading device 12, into the tanks of the tanker 14.

An embodiment of a method for the assembly of an offshore system for conversion of energy comprises the following steps:

• Selecting an existing offshore production platform 100 (fig. 4), in this edition a gravity based offshore fossil fuel production platform with a concrete foundation 16. The foundation 16 comprises a cluster of a variety of upright cylindrical shaped cells 102 which together form a base with a roughly rectangular or hexagon footprint. The lower part of each cell 102 holds permanent ballast 104. Above the ballast, there is an impermeable separation 106. Above the separation is a storage tank 20 for hydrocarbon liquids. In the productive phase of the field these tanks 20 were used for the storage of oil and for the separation of oil and water. On top of the foundation 16, towers 107 are provided, which support a subframe, or module support frame 108. The subframe 108 supports topside modules 109, such as fossil fuel production equipment 112,114, and crew accommodation 116. Re-using an existing offshore production platform 100 offers cost savings, as described above. Furthermore, it provides environmental advantages as no energy is needed for the lifting and transport of the platform, nor for its demolition, and because no or less waste has been produced.

• Removing the fossil fuel production equipment from the existing offshore fossil fuel production platform 100 (fig. 5), in this case removing the drilling 112 and fossil fuel process 114 modules with a crane vessel 118. The accommodation 116 for the crew and some of the existing miscellaneous structures remain and are refitted for the new use of the platform (fig. 6).

• Positioning the renewable liquid fuel synthesis plant 4 on the foundation 16 or the existing offshore production platform 100 (Fig. 7). Using the foundation 16 offers the advantages as described above, i.e. it reduces the downtime of the renewable liquid fuel synthesis plant 4.

• Electrically connecting the least one energy converter, in this embodiment a wind energy converter 2 with the renewable liquid fuel synthesis plant (fig. 1). Thanks to the fixed foundation 16, a large number of energy converters, such as present in a large scale wind farm (not shown), can be connected to the renewable liquid fuel synthesis plant 4.

• Fluidly connecting the inlet 8 with the sea (fig. 1).

• Fluidly connecting the existing storage tanks 20 with the renewable liquid fuel synthesis plant 4 and the offloading device 12.

Several variants are possible within the scope of the attached claims. The features of the preferred described above may be replaced by any other feature within the scope of the attached claims, such as the features described in other writings, and in the following paragraphs.

The offloading device or an alternative embodiment is connected to a pipeline which transports the renewable liquid fuel to the shore. In an embodiment, the CO2 module is suitable for the sequestration or CO2 from the atmosphere. In an embodiment, the carbon dioxide required for the production of the renewable liquid fuel can be fed into the process from an industrial carbon capture source. In yet another embodiment, the production of clean fuels coincides with the production of fossil fuels, e.g. in the case of an oil or gas field is not depleted completely. In an embodiment, a fuel-powered electricity generator is provided as additional source of electricity. The CO2 produced by the generator is used for the production of the renewable liquid fuel.

In an embodiment, a renewable liquid fuel, such as an alcohol or hydrocarbon, is produced directly from CO2 and water, without the intermediate step of H2 production.

In an embodiment, the renewable liquid fuel synthesis plant comprises a hydrocarbon module, in particular for the production of hydrocarbons from CO2 and H2. In an embodiment, formic acid (CH2O2) is produced in a formic acid module next to, or instead of, hydrocarbons or alcohols. In an embodiment, a combination module produces more than one product, more in particular hydrocarbons and alcohols.

In an embodiment, the renewable liquid fuels are supplied to seagoing vessels such as bunker fuels, by means of suitable offloading equipment.

In an embodiment, the H2 module is provided in the renewable energy converters, connected to the renewable liquid fuel synthesis plant by pipeline for further processing in to a liquid fuel.

In an embodiment, energy storage in batteries takes place to shave or peak loads of the energy converters.

In an embodiment, the O2 produced is cooled to liquid oxygen and stored in cryogenic containers, for offloading into vehicles.

An embodiment comprises a variety of energy converters, in particular a variety of the same type of energy converters or a variety of different types of energy converters.

The above described expiry of the invention enable harvesting renewable energy in very remote offshore locations where the wind and wave resources are abundant. No long electricity cables from the remote location to the shore are required. The invention allows the production of alternative non-fossil fuel for use in transportation vehicles, ships and airplanes on an industrial scale. The invention provides a feasible conversion option for existing deep-water offshore platforms from fossil-fuel to carbon5 neutral fuel production. Clean fuels produced according to the invention are fully climate neutral: the amount of CO2 released from their combustion is the same amount as was consumed in the synthesis.

Claims (16)

CONCLUSIONS 1. Offshore system for converting energy, comprising: at least one energy converter (2) for converting renewable energy into electrical energy, a synthesis plant (4) for renewable liquid fuel comprising at least one electrical connection (6) with the energy converter (2) and an inlet (8) for seawater (10), a discharge device (12) for transferring the renewable liquid fuel to a vehicle (14) and / or a pipeline, characterized in that the offshore system (1) further comprises a foundation (16) which is in a operating condition of the offshore system (1) rests on a seabed (18) and supports the synthesis plant (4) for renewable liquid fuel. An offshore energy conversion system according to claim 1, wherein the foundation (16) is made of concrete. An offshore energy conversion system according to claim 1 or 2, wherein the foundation (16) is a gravity-based foundation (16) of a former fossil fuel production platform. An offshore energy conversion system according to any one or more of the preceding claims, further comprising at least one storage tank (20) for storing the produced liquid fuel. An offshore energy conversion system according to claim 4, wherein the at least one storage tank (2) is provided under water, in particular in the foundation (16). An offshore energy conversion system according to any one or more of the preceding claims, wherein the at least one energy converter (2) is one of the list: a wave energy converter (22), an ocean thermal energy conversion plant, an ocean flow energy converter, a tidal energy converter, a solar power plant, a geothermal power plant, a wind energy converter (2), in particular a floating wind turbine (24). An offshore energy conversion system according to any one or more of the preceding claims, wherein the renewable liquid fuel synthesis plant (4) comprises a CO2 module for capturing CO2 from the atmosphere or seawater and / or the synthesis plant (4) for renewable liquid fuel comprises an hh module for the production of H2, in particular by electrolysis of seawater. An offshore energy conversion system according to any one or more of the preceding claims, wherein the renewable liquid fuel synthesis plant (4) comprises an alcohol module for the production of ethanol, methanol, or butanol, and / or the renewable liquid fuel synthesis plant (4) comprises a hydrocarbon synthesis module for the production of one or more hydrocarbons, in particular from H2 and CO2. An offshore energy conversion system according to any one or more of the preceding claims, wherein the renewable liquid fuel synthesis plant (4) comprises a water treatment module for treating and purifying seawater. A method for assembling an offshore energy conversion system according to any or more of the preceding claims, comprising the steps of: providing the foundation on the seabed, positioning the renewable liquid fuel synthesis plant on the foundation, electrically connecting the at least one energy converter to the renewable liquid fuel synthesis plant, bringing the inlet to the sea in fluid communication, and in fluid connection of the renewable liquid fuel synthesis plant to the discharge device. The method of claim 10, wherein the step of providing the foundation comprises selecting an existing offshore production platform, and the step of positioning the renewable liquid fuel synthesis plant positioning the renewable liquid fuel synthesis plant on the existing offshore production platform. 5 The method of claim 10 or 11, further comprising the step of removing fossil fuel production equipment from the existing offshore production platform. The method of claim 10, 11, or 12, further comprising the step of re-equipping at least a portion of an existing topside of the existing offshore 10 production platform. The method of any one or more of claims 10-13, further comprising the step of providing at least one storage tank in fluid communication with the renewable liquid fuel synthesis plant and the discharge device. The method of any one or more of claims 10-14, wherein the at least one storage tank is an existing storage tank of an existing offshore production platform. 16. Use of an offshore energy conversion system according to any or more of claims 1-9 for the production of renewable liquid fuel from seawater and CO2.