Method for producing hydrogen and oxygen from an underground system

Abstract

A system and method for producing hydrogen comprising at least one electrolyzer adapted to be installed within a subterranean formation, at least one electrical supply cable having a selected length extending from the at least one electrolyzer to a surface power source, at least one supply tubing string having a selected length extending from the at least one electrolyzer to a surface water supply, and at least one collection tubing string having a selected length extending from the at least one electrolyzer to a surface collection location, the method including providing a well from the surface to a subterranean formation, installing at least one electrolyzer within the well, providing a supply electrical power to the at least one electrolyzer, providing a supply water to the at least one electrolyzer, producing hydrogen gas in the electrolyzer, and collecting and transporting the produced hydrogen gas to the surface.

Description

[Technical field]

[0001] The present disclosure relates generally to in-situ geothermal electrolysis underground production of hydrogen and oxygen. [Background technology]

[0002] Considering climate change, there is a need to transition the world's energy systems to clean, zero greenhouse gas (GHG) emission energy systems. Currently, the majority of the energy supply used by humanity is derived from hydrocarbon fuels such as gasoline, diesel, kerosene, crude oil, fuel oil, bitumen, coal, and peat. One of the key challenges facing the use of hydrocarbon fuels is the release of carbon dioxide, a potent greenhouse gas, during consumption (when the fuel is burned).

[0003] There is a continuing desire to produce fuels such as hydrogen that have less carbon dioxide emissions. Additionally, hydrogen is a useful chemical feedstock for the production of commodity chemicals and materials such as ammonia, methanol, and steel.

[0004] There are several ways to commercially produce hydrogen. The most commonly used commercial method to produce hydrogen is steam methane reforming, which reacts with steam to produce a mixture of carbon monoxide, carbon dioxide, hydrogen, and water (steam). This mixture is called synthesis gas. Hydrogen is separated from the synthesis gas. In some cases, heavier hydrocarbons are steam reformed to produce hydrogen. One challenge facing the steam reforming method is that it produces carbon dioxide, which is usually released into the atmosphere. The carbon dioxide can be sequestered or converted into products, but this requires additional energy and associated emissions, as well as cost.

[0005] Another commercial production method is by electrolysis, which uses an electric current to split water into its constituent elements, namely oxygen and hydrogen. This method requires electricity, which can be generated from fossil fuels (e.g., oil, gas, coal) or renewable sources (e.g., solar, wind, geothermal) or nuclear sources. If renewable or nuclear energy is used, operational greenhouse gas emissions are reduced to near zero or zero production. However, current electrolysis methods are expensive and produce hydrogen at low pressures, requiring additional energy to increase the pressure and associated emissions.

[0006] Patent Document 1 describes a method for producing hydrogen by electrolysis using a membrane-free electrolysis cell consisting of separate anode and cathode cells supplied by a DC power source.

[0007] US Pat. No. 5,399,433 describes a method for producing hydrogen by electrolysis, in which the hydrogen produced is stored in a gas reservoir and then fed directly to an internal combustion engine.

[0008] Patent Document 3 describes a method for producing hydrogen by electrolysis using sunlight, in which a photovoltaic cell is connected to an electrolyzer for hydrogen production.

[0009] Patent Document 4 describes a method for producing hydrogen by electrolysis, in which a system is composed of a first compartment equipped with an electrode for reducing water to hydrogen and another separate second compartment equipped with an electrode for producing oxygen, the electrode being electrically connected to the electrode of the first compartment.

[0010] Patent Document 5 describes an apparatus and method for producing hydrogen using a catalytic electrolysis cell.

[0011] US Patent No. 6,399,633 provides an apparatus and method for electrolyzing water using an alkaline medium for hydrogen production. The method comprises a first rechargeable battery and a second rechargeable battery, the first battery operating in a discharge mode in which hydrogen gas is produced, and the second battery operating in a charge process in which oxygen gas is produced. Operation of the system consists of repeated cycling between the two batteries, producing hydrogen and oxygen alternately between the two batteries.

[0012] US Patent No. 5,399,633 describes a multi-cell hydrogen production and compression device. Water is fed into the device and electrochemically split into oxygen gas and hydrogen protons. The hydrogen protons are attracted to the first anode, forming hydrogen gas. The moist hydrogen is then fed to the anode of the second cell, where it is again split into protons. The protons are attracted to the cathode of the second cell. With the ability of differential pressure operation through a proton exchange membrane, the device is claimed to produce high pressure hydrogen with greater efficiency than a single differential pressure cell or a single identical pressure differential cell. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] U.S. Patent No. 7,326,329 [Patent Document 2] U.S. Pat. No. 7,191,737 [Patent Document 3] European Patent No. 1,716,602 [Patent Document 4] U.S. Pat. No. 10,487,408 [Patent Document 5] International Patent Application Publication No. 2006 / 113463 [Patent Document 6] International Patent Application Publication No. 2021 / 099986 [Patent Document 7] U.S. Patent No. 8,282,811 Summary of the Invention [Problem to be solved by the invention]

[0014] None of the above mentioned conventional methods produce hydrogen and oxygen under pressure, all hydrogen and oxygen are produced under atmospheric pressure. All conventional methods require subsequent design constraints to produce pressurized hydrogen in an atmospheric environment. Typically, hydrogen needs to be compressed to over 350 atmospheres to be transported in a conventional tube trailer. [Means for solving the problem]

[0015] According to a first embodiment, a system for producing hydrogen is disclosed that includes at least one electrolyzer adapted to be installed within an underground structure, at least one electrical supply cable having a length selected to extend from the at least one electrolyzer to a surface power source, at least one supply tubing string having a length selected to extend from the at least one electrolyzer to a surface water supply, and at least one collection tubing string having a length selected to extend from the at least one electrolyzer to a surface collection site.

[0016] The electrolyzer may include at least one cathode formed from a material selected from the group consisting of ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold on a substrate formed from a material selected from the group consisting of carbon, titanium dioxide, graphene, and alumina. The electrolyzer may include at least one anode formed from a material selected from the group consisting of iridium oxide, ruthenium oxide black, and perfluoroalkylsulfonic acid. The electrolyzer may include at least one proton exchange membrane to allow separation of oxygen and hydrogen production points within the electrolyzer.

[0017] The electrolyzer, the water tubing string, the hydrogen tubing string, and the oxygen tubing string can be surrounded by water. The at least one electrolyzer can include at least one electrolysis cell separated into a first compartment with electrodes for reducing water to hydrogen and a second compartment separate from the first compartment with electrodes for producing oxygen.

[0018] A plurality of electrolytic cells may be connected together in series or parallel within the well. The system may further comprise a pressure regulator adapted to control a pressure of at least one of the hydrogen or oxygen produced in either one of the hydrogen tubing strings or the oxygen.

[0019] According to a first embodiment, a method for producing hydrogen is disclosed, the method including the steps of providing a borehole from the surface to an underground layer, installing at least one electrolyzer in the borehole, providing a supply power to the at least one electrolyzer, providing a supply water to the at least one electrolyzer, producing hydrogen gas in the electrolyzer, and collecting and transporting the produced hydrogen gas to the surface.

[0020] Supply power may be transported from the surface to the at least one electrolyzer via a power supply cable extending therebetween. Feed water may be transported from the surface to the at least one electrolyzer via a supply tubing string extending therebetween. The feed water may be introduced into the supply tubing string at high pressure. The feed water may be introduced into the supply tubing string at an elevated temperature.

[0021] The method may further include transporting the produced hydrogen in at least one collection tubing string extending from the at least one electrolyzer to the surface. The method may further include controlling the surface production of hydrogen or oxygen or both from each tubing string to maintain a desired pressure of the gas in each tubing string. The method may further include utilizing underground wells as structural support for storing the produced hydrogen prior to transporting it to the surface. The pressure of the hydrogen and oxygen gas produced in each tubing string may build up until it reaches a desired pressure up to, but not exceeding, the maximum underground storage pressure of the tubing string.

[0022] The method may further include determining a hottest location in the well and installing at least one electrolyzer at the hottest location. The method may further include installing at least one electrolyzer in a deepest portion of the well. The well may be selected to be an oil reservoir after a steam recovery process or a heat recovery process.

[0023] The produced hydrogen can be passed through a fuel cell to generate electrical power. The produced water can be injected into a well and fed to an electrolyzer. The produced hydrogen can be combusted to generate at least one of electrical power, heat, and steam. The produced water or condensed steam can be injected into a well and fed to an electrolyzer. The electrical power used by the electrolyzer can be provided from at least one of a solar photovoltaic cell, wind, hydro, nuclear, and a fuel generator. At least one of the produced oxygen and hydrogen can be passed through a turbine generator to produce at least one of rotational energy and electrical power. Hydrogen can be reduced from water in a first compartment using electrodes to reduce water to hydrogen, and oxygen can be reduced from water in a second compartment located separately from the first compartment using electrodes electrically connected to the electrodes of the first compartment.

[0024] The water in the electrolyzer can be hydrostatically pressurized at the submerged depth of the electrolyzer. The produced oxygen and hydrogen can be under electrolyzer pressure and are sent to the electrolyzer and respective production tubing strings connected to the surface.

[0025] According to a first embodiment, a method for producing hydrogen from a subsurface system is disclosed, comprising the steps of providing a well from the surface to the subsurface, installing at least one electrolyzer at one or more depths within the well, supplying water to the electrolyzer via a connection, supplying an electric current to the electrolyzer to produce oxygen and hydrogen, separating the produced oxygen and hydrogen and filling at least one hydrogen tubing string and at least one oxygen tubing string to a desired pressure, and separately producing gas from the tubing strings at the desired target pressure at the surface. The method further comprises generating energy through at least one of passing at least one of the high pressure oxygen and hydrogen through a turbine to generate rotational energy, passing at least one of the high pressure oxygen or hydrogen through a turbine and a generator to generate electricity, supplying the produced hydrogen to a combustion engine and combusting it to obtain rotational energy, supplying hydrogen to a combustor to obtain heat, and supplying hydrogen to a fuel cell to generate electricity. The method further includes providing water produced from the energy generating step to feed the electrolyzer, delivering high pressure oxygen at a desired pressure to an above-ground storage vessel for storage or transport, and delivering high pressure hydrogen at a desired pressure to an above-ground storage vessel for storage or transport.

[0026] According to a further embodiment, there is provided a method for producing hydrogen from an underground system, comprising the steps of: a. providing a well from the surface to the subsurface; b. locating at least one electrolyzer at one or more depths within the well; c. supplying water to the electrolyzer via a connection; d. supplying electrical current to the electrolyzer to produce oxygen and hydrogen from any power source, including solar, wind, hydroelectric, geothermal, nuclear, fossil fuels (natural gas, hydrocarbon fuels, or coal), and other oxidizable fuels (e.g., nitrogen-based fuels); e. Separating the produced oxygen and hydrogen and charging them into two separate tubing strings (pipes), each string being connected to an electrolyser and each gas being charged to a desired pressure in its respective tubing string; f. separately producing gas from the tubing string at a desired target pressure at surface; g. passing the high pressure oxygen and / or hydrogen through a turbine to generate rotational energy; h. passing the high pressure oxygen and / or hydrogen through a turbine and generator to generate electricity; i. supplying the hydrogen after steps a to h to a combustion engine and combusting it to obtain rotational energy; j. supplying the hydrogen after steps a to h to a combustor to obtain heat; k. supplying the hydrogen after steps a-h to a fuel cell to generate electrical power; l. taking the water produced from steps i to k and using it to feed the electrolyser (step c); m. delivering the high pressure oxygen at a desired pressure to an above-ground storage vessel for storage or transport; n. Delivering the high pressure hydrogen to an above-ground storage vessel at a desired pressure for storage or transportation; A method is disclosed that includes:

[0027] Other aspects and configurations of the present disclosure will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.

[0028] The accompanying drawings form part of this disclosure, each drawing illustrating an exemplary embodiment and like reference numerals designate corresponding parts in each drawing. [Brief description of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram of a system for producing hydrogen in a subterranean well according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a cross-sectional view of the electrolyzer of the system of FIG. 1 installed in a cased vertical well where electrical current and water are supplied to the electrolyzer and hydrogen and oxygen gases are produced and stored in respective tubing strings. [Diagram 3] Cross-sectional view of the electrolyzer of the system of Figure 1 installed in an open-hole vertical well, where electrical current and water are fed to the electrolyzer and hydrogen and oxygen gases are produced and stored in respective vertical tubing strings. [Figure 4a] FIG. 2 is a cross-sectional view of the electrolyzers of the system of FIG. 1 in a vertical well, according to a further embodiment of the present disclosure, where a series of electrolyzers are supplied with electrical current and water to produce and store hydrogen and oxygen gas in respective vertical tubing strings. [Figure 4b] A cross-sectional view of the well and tubing string of Figure 4a above and in position at the electrolyzer. [Figure 5a] FIG. 2 is a cross-sectional view of the electrolyzers of the system of FIG. 1 in a vertical well according to a further embodiment of the present disclosure, where electrical current and water are fed to a series of dual chamber electrolyzers and hydrogen and oxygen gases are produced and stored in respective vertical tubing strings. [Figure 5b] A cross-sectional view of the well and tubing string of Figure 5a above and in position at the electrolyzer. [Figure 6a] FIG. 2 is a cross-sectional view of the electrolyzers of the system of FIG. 1 in a vertical well, according to a further embodiment of the present disclosure, where electrical current and water are supplied to a series of electrolyzers and hydrogen and oxygen gases are produced and stored in respective concentrically arranged vertical strings of tubing. [Figure 6b] A cross-sectional view of the well and tubing string of Figure 6a above and in position at the electrolyzer. [Figure 7a] FIG. 2 is a cross-sectional view of the electrolyzers of the system of FIG. 1 in a vertical well according to a further embodiment of the present disclosure, where electrical current and water are fed to a series of three-chamber electrolyzers and hydrogen and oxygen gases are produced and stored in respective vertical tubing strings. [Figure 7b] A cross-sectional view of the well and tubing string of Figure 7a above and in position with the two-chamber electrolyzer. [Figure 8] FIG. 2 is a cross-sectional view of the electrolyzer of the system of FIG. 1 in a cased horizontal well, according to a further embodiment of the present disclosure, where electrical current and water are supplied to the electrolyzer, thereby producing hydrogen gas and oxygen gas, which are stored in respective horizontal tubing strings. [Figure 9] FIG. 2 is a cross-sectional view of the electrolyzer of the system of FIG. 1 in an open-hole horizontal well according to a further embodiment of the present invention, in which electrical current and water are supplied to the electrolyzer, thereby producing hydrogen gas and oxygen gas, which are stored in respective horizontal tubing strings. [Figure 10] FIG. 2 is a diagram of an electrolyzer of the system of FIG. 1 capable of producing oxygen and hydrogen from water. [Figure 11] FIG. 2 is a side view of an electrolyzer of the system of FIG. 1 installed in a well according to a further embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Aspects of the present disclosure will now be described with reference to exemplary apparatus, methods and systems. Referring to Figure 1, an exemplary system for producing hydrogen according to a first embodiment is shown in schematic form.

[0031] Throughout the following description, specific details are described to provide a more complete understanding to those skilled in the art. However, well-known elements may not be shown or described in detail to avoid unnecessarily obscuring the present disclosure. The following description of examples of the present invention is not intended to be exhaustive or to limit the present invention to the precise form of any exemplary embodiment. Thus, the description and drawings should be considered in an illustrative sense, and not in a restrictive sense.

[0032] In broad terms, the exemplary methods and systems described herein use an electrolyzer located underground to produce hydrogen and oxygen gas from water. Performing electrolysis underground allows for improved thermodynamics by utilizing geothermal (heated) conditions to support the underground structure of the wellbore to achieve high pressure storage, and allows for downhole operation under pressure to achieve better separation and gas removal.

[0033] Generally, the present specification describes systems and methods for converting water to produce hydrogen and oxygen. The method includes injecting water and power into a well to feed one or more electrolyzers located in the well, which convert the water into hydrogen gas and oxygen gas, which are then fed into respective tubing strings for storage therein at a desired pressure. The gas is then removed from the tubing strings at a desired pressure at the surface below the electrolyzer system pressure. One or both of the produced gases may be vented to the atmosphere or collected for use in a subsequent process. The produced hydrogen may be consumed at the surface to generate power or heat, or both, or as a chemical feedstock to produce other materials.

[0034] FIG. 1 shows one embodiment of the system generally taught at 10. One or more electrolyzers 12 are disposed within a well 9 and within a soil layer 8 at designated locations within the well, such as, for example and as a non-limiting example, within a target zone 7. To achieve maximum pressure of produced gas, it is preferable to place the electrolyzer at the bottom of the well if the well is vertical, or along the horizontal portion 4 of a horizontal well. To maximize the efficiency of electrolysis, the electrolyzer is placed at the hottest location along the well. The location of the highest temperature along the well can be obtained from a temperature survey along the well. The electrolyzer 12 disposed within the well 9 is connected to the surface 6 via four lines, a power line 20 and three tubing strings. In particular, a water tubing string 30 supplies water to the electrolyzer, a hydrogen tubing string 40 is used to collect hydrogen from the electrolyzer 12, and an oxygen tubing string 50 is for collecting oxygen from the electrolyzer 12, each produced by electrolysis of water supplied to the electrolyzer. Water may be pumped to the electrolyzer from the surface as described herein or may optionally be obtained from surrounding soil and rock formations. It will be appreciated that such water is desirably relatively pure with low salinity to extend the life of the electrolyzer. The hydrostatic pressure resulting from the height of the water in the tubing strings sets the minimum pressure for the operation of the electrolyzer and the hydrogen and oxygen gases produced therein. The tubing strings for each gas produced are regulated at the surface such that the pressure of the gases in each tubing string builds up as they are produced. Once the desired pressure for each of the gases is reached, each in its respective tubing string, the gases can be produced at the surface at the desired pressure, which may be controlled using regulators 42 and 52 or equivalent devices. In the spaces between the tubing strings, the external spaces may be filled with water to provide a mass transfer resistance to the loss of hydrogen from the hydrogen tubing strings.

[0035] 11, an exemplary electrolyzer 10 is installed in a well 8. The electrolyzer 10 may include one or more surface treatments to aid in heat transfer to the electrolyzer 10, which may include, by way of non-limiting example, fins 12, etc. The electrolyzer 10 includes a water string 20 and power lines 30 that extend from the surface to the electrolyzer, and a hydrogen tubing string 40 and an oxygen tubing string 50 that extend from the electrolyzer to the surface. As is well known, electrolyzers can produce oxygen and hydrogen from water.

[0036] In particular, as illustrated in FIG. 10 showing a simplified configuration, the electrolyzer 12 includes an anode porous support 14, an anode catalyst 15, a proton exchange membrane 16, a cathode catalyst 17, and a cathode porous support 18. The membrane 16 separates the electrolysis cell into a first compartment with a cathode or first electrode for reducing water to hydrogen and a separate, separate second compartment, which may be located separate from the first compartment, with an anode or second electrode for producing oxygen, which electrode is electrically connected to the electrode of the first compartment. Multiple electrolysis cells may be connected together in series or parallel within the well, as described further below and shown in the figures. The electrolyzer may use a proton exchange membrane to allow separation of the points of production of oxygen and hydrogen within the electrolyzer. The proton exchange membrane allows transport of hydrogen ions and facilitates the formation of hydrogen gas in a separate compartment from the formation of oxygen gas. The electrolyzer may use one or more or combinations of the following materials for the electrodes: precious metal materials such as ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and / or gold deposited on supports of carbon, titanium dioxide, graphene, and / or alumina as cathode catalysts for high activity and stability; iridium oxide and / or ruthenium oxide black as anode catalysts for high activity and stability; perfluoroalkylsulfonic acids, known by trade names such as Nafion, Flemion, or Aquivion, that balance area-specific resistance, low gas crossover, and mechanical robustness; and finally, porous steel, titanium, and / or aluminum, or other metal separators to maintain mechanical support for the cell.

[0037] At the start of operations, the exterior space and the water tubing string may be completely filled with water. The oxygen and hydrogen tubing strings may also be initially filled with water.

[0038] The electrolyzer is then powered and water is expelled from the gas tubing string as gas is produced. As the system continues to consume water and produce more hydrogen and oxygen, water is fed into the water tubing string and gas is removed at the surface at the desired pressure. Optionally, hydrogen may be collected in the annular space around the electrolyzer and / or in a feed tube between the electrolyzer and transported to the surface. The electrolyzer may use a control system to prevent water from entering the oxygen and hydrogen tubing strings.

[0039] In a typical continental crust, over the first few kilometers, the temperature gradient is on the order of about 25°C per km of depth. This means that for a 3 km deep well, such as those typically found in tight rock natural gas reservoirs, temperatures can be on the order of 75°C. Placing the electrolyser at this depth allows operation under geothermal heating, resulting in improved electrical efficiency. One advantage of this method and device is the natural geothermal heat. Optionally, the water supplied to the electrolyser can be heated to the desired temperature at the surface and then injected into the well.

[0040] For a target zone at a depth of 3 km, the hydrostatic pressure at that depth is the sum of the atmospheric pressure and the liquid head, or 101325 Pa + (1000 kg / m 3 )(9.81m / s 2 )(3000m)=29,531kPa=291.5 atmospheres. This means that if the electrolyzer is installed at this depth, oxygen and hydrogen gases will be produced at 291.5 atmospheres. Therefore, each of the gases will accumulate in their respective tubing strings, so that when the tubing strings are closed at the surface, they will accumulate and reach the production pressure. Gas can then be produced at the surface at pressures up to the production pressure.

[0041] Details of the electrolyzers and their placement in vertical or horizontal cased and open hole wells are shown in Figures 2-9. Figure 10 shows details of a single cell electrolyzer. These single cells can be stacked together to make electrolyzer stacks, shown with electrolyzer connections in the figure. Electrolyzer configurations include, but are not limited to, compartmental and cylindrical shapes compatible with vertical or horizontal wellbore configurations, or both. Electrolyzer stacks are interconnected and can be easily constructed across the entire wellbore section of desired length. Each tubing string is connected to the adjacent electrolyzer stack, thereby allowing the transfer of fluids from one electrolyzer to the other.

[0042] In particular, the tubing string can be sized to occupy nearly the entire cross section of the wellbore, as shown in FIG. 2. A cased wellbore is a wellbore surrounded by solid casing material 5 to maintain the diameter of the wellbore. In most cases, the solid casing material 5 is made from steel or other common piping materials, as is commonly known. The combination of the existing casing 5 and the surrounding subsurface material allows for the safe storage of very high pressure gas within the tubing string. In another embodiment, the casing itself can be used to store high pressure gas, for example, as a non-limiting example, within the annular space between the tubing and the casing.

[0043] Additionally, as shown in Figure 3, the system can be installed in an open hole well whereby the walls of the open hole provide most of the structural strength for storing the high pressure gas within the tubing string. In another embodiment, the open hole itself can be used to store the high pressure gas. While Figures 2-7b show use in a vertical well, it will be understood that the system can also be utilized in horizontal wells or wells of different orientations, as shown in Figures 8 and 9.

[0044] Optionally, the system may utilize a series of electrolysers 12, as shown in Figures 4a and 4b. In such an embodiment, each of the electrolysers are interconnected with a connector 11 to allow for the passage of water to each electrolyser and the passage of hydrogen and oxygen gases to the surface. As shown, the hydrogen lines in Figure 4a may be larger than the oxygen strings to increase the storage of produced hydrogen.

[0045] Additionally, a series of dual chamber electrolysers may be used with each of the electrolysers connected to each other in series and parallel via cell separators 19 to allow for the passage of water to each electrolyser and the passage of hydrogen and oxygen gases to the surface, as shown in FIG. 5a. The electrolysers may be connected to each other using any suitable connector type and to any associated piping. Additionally, each of the electrolysers may be connected to each other to allow for the passage of water to each electrolyser and the passage of hydrogen and oxygen gases to the surface, as shown in FIG. 6a. The water tubing string, hydrogen tubing string, and oxygen tubing string may be concentric with each other, with two strings located within the other string, each string located within the outer string, or fed into a collection chamber as shown in FIG. 7.

[0046] The method and apparatus can be used on water in the subsurface zone in which the electrolyzer is to be installed if the water has a low salinity or total dissolved solids. The solubility of hydrogen in water can be very low, so a water blanket surrounding the hydrogen tubing string acts as a seal to prevent hydrogen loss.

[0047] The method may also be used in oil and gas reservoirs, geothermal reservoirs, or any subterranean structure in which wells or open holes exist or can support them. Old wells that have outlived their intended use, such as abandoned oil or gas wells, may also be used in the methods described herein. By way of non-limiting example, the system may be utilized in existing abandoned wells, including post-stream oil sands reservoirs, steam-assisted gravity drainage (SAGD) wells, where it will be appreciated that residual heat from a previous SAGD process enhances the operation of the electrolyzer.

[0048] The method and system of the present invention can be used in dry rock or in porous rock with high moisture content or in groundwater zones. EXAMPLES

[0049] The basis of this model utilizes the first law of thermodynamics to predict operational costs. This law assumes that all energy in a system is conserved. Typically, the electrochemical reaction process for hydrogen production uses electricity to split liquid water into hydrogen and oxygen gas at standard temperature and pressure. However, the system can add heat as a form of energy to reduce the power consumed. The idea of ​​adding heat to an electrochemical system for hydrogen production has been studied since the 1980s, but the concept of high temperature electrolysis is gaining attention due to forecasts of expanding hydrogen markets and recent advances in electrochemical materials.

[0050] Underground wells provide a geothermal source, giving the company an economic advantage in the race to produce hydrogen. In many geothermal systems in Alberta, temperatures range from 50°C to 200°C, but other locations, such as Iceland, can vary in temperature and have wells with temperatures as high as 500°C.

[0051] Applying the laws of electrochemistry, the ambient temperature relative to the electrochemical cell, along with recent publications and industry specifications for the performance of electrolysis cells, can predict the amount of electricity that will be consumed at a given production rate.

[0052] The hydrogen production rate is primarily affected by the choice of materials, cell geometry, ambient temperature, and power consumption. The choice of materials, cell geometry, and heat input determine the theoretical minimum power requirement to enable the water splitting reaction, which is a combination of purposefully selected electrodes and membrane materials exposed to high temperatures. This means that the reaction will occur if power is provided that exceeds the minimum power requirement. The theoretical minimum power requirement is dictated by the cell potential. The cell geometry determines how much product can be produced at a given production rate based on the surface area of ​​the electrodes.

[0053] Furthermore, these properties (i.e., material, geometry, temperature, and power supply) are expected to affect the reaction kinetics, which are difficult to predict mathematically. These losses arise from ohmic resistance, ion migration, and ion diffusion. Optimizing these properties is expected to have a beneficial effect, thereby reducing the cell potential.

[0054] Table 1 compares four example operating scenarios, all of which operate at electricity rates of $0.03 or $0.04 per kWh and 2A / cm 2 The current density is selected based on the typical current density of hydrogen electrolysis cells and is in the range of 1 to 3 A / cm. 2 The differences between these three scenarios are the ambient temperature and the overpotential.

[0055] [Table 1]

[0056] In any of the examples listed in Table 1, if the water is pressurized at the surface, the water pressure in the electrolyser will be greater than the hydrostatic pressure, at which hydrogen and oxygen gases will be produced. Thus, even shallow systems can produce high pressure hydrogen and oxygen gases.

[0057] The above examples provide exemplary methods for producing hydrogen and oxygen at the surface using downhole electrolysis under high pressure conditions. An advantage of the methods and apparatus described herein is that they utilize geothermal heat to increase the efficiency of the electrolysis and produce hydrogen under pressure.

[0058] The hydrogen produced by the methods described herein can be used in fuel cells 60 on the surface to generate electricity, or can be combusted to produce steam that can be used to generate electricity or other in situ oil recovery processes, or sold as an industrial chemical feedstock.

[0059] The hydrogen produced can be passed through a fuel cell to generate electricity, and the water produced can be injected into a well to supply an electrolyser. The hydrogen produced can be combusted to generate electricity or heat or steam, and / or the water produced or condensed steam can be injected into a well to supply an electrolyser. The hydrogen produced can be used as a chemical feedstock to produce other chemicals.

[0060] Electricity that may be used in the electrolyzer may come from solar photovoltaic cells, wind, hydro, nuclear, or fuel generators. The oxygen and / or hydrogen produced may be passed through a turbine generator 70 to generate rotational energy or electricity. The apparatus may be used to produce hydrogen when intermittent power is available, and the stored hydrogen is used when power is not available. The apparatus and method may be used in post-vapor recovery process or post-heat recovery process oil reservoirs that are thermally stimulated to high temperatures.

[0061] As is apparent from the above, one of ordinary skill in the art can readily determine obvious variations which provide the described functionality, and all such variations and functional equivalents are intended to be included within the scope of the present invention.

[0062] Unless the context clearly indicates otherwise, throughout this specification and claims: "Comprise", "comprising" and the like are to be construed in their inclusive sense and not in their exclusive or exhaustive sense, i.e. "including but not limited to". "Connected," "interconnected," "coupled," or variations thereof means a direct or indirect connection or coupling between two or more elements, and the coupling or connection between the elements may be physical, logical, or a combination thereof. The words "herein," "above," "below," and words of similar import, when used to describe this specification, shall refer to this specification as a whole and not to specific portions of this specification. · "Or", in the case of a list of two or more items, covers the following interpretations of the word: any of the items in the list, all of the items in the list, and all of any combination of the items in the list. · The singular forms "a", "an" and "the" include the appropriate plurals.

[0063] Unless the context clearly indicates otherwise, throughout this specification and the appended claims, directional terms such as, for example, "vertical," "transverse," "horizontal," "upward," "downward," "forward," "backward," "inward," "outward," "vertical," "transverse," "left," "right," "front," "back," "top," "bottom," "below," "above," "under," and the like, used in this specification and the appended claims (if any) are dependent on the particular orientation of the device as described and illustrated. The subject matter described herein can assume various alternative orientations. Thus, these orientation terms are not precisely defined and should not be interpreted narrowly.

[0064] Specific examples of methods and systems are described herein for illustrative purposes. These are merely examples. The techniques provided herein may be applied in contexts other than the exemplary contexts described above. Many changes, modifications, additions, omissions, and substitutions are possible in the practice of the present invention. The present invention includes variations of the described embodiments that will be apparent to those skilled in the art, including variations obtained by replacing configurations, elements, and / or operations with equivalent configurations, elements, and / or operations, mixing and matching configurations, elements, and / or operations of different embodiments, combining configurations, elements, and / or operations of the embodiments described herein with configurations, elements, and / or operations of other technologies, and / or omitting combinations of configurations, elements, and / or operations from the described embodiments.

[0065] While particular embodiments have been described and illustrated, such embodiments should be considered as illustrative only and not limiting of the disclosure as interpreted according to the appended claims.

Claims

1. at least one electrolysis device adapted to be installed within an underground structure; at least one electrical supply cable having a length selected to extend from said at least one electrolyzer to a surface electrical source; at least one string of supply tubing having a length selected to extend from said at least one electrolyzer to said surface water supply; at least one collection tubing string having a length selected to extend from said at least one electrolyzer to a collection site on the surface; A system for producing hydrogen comprising:

2. 10. The system of claim 1, wherein the electrolyzer comprises at least one cathode formed from a material selected from the group consisting of ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold on a substrate formed from a material selected from the group consisting of carbon, titanium dioxide, graphene, and alumina.

3. 10. The system of claim 1, wherein the electrolyzer comprises at least one anode formed from a material selected from the group consisting of iridium oxide and ruthenium oxide black and perfluoroalkylsulfonic acid.

4. 10. The system of claim 1, wherein the electrolyzer comprises at least one proton exchange membrane to enable separation of oxygen and hydrogen production points within the electrolyzer.

5. 10. The system of claim 1, wherein the electrolyzer, the water tubing string, the hydrogen tubing string, and the oxygen tubing string are surrounded by water.

6. 10. The system of claim 1, wherein the at least one electrolyzer comprises at least one electrolysis cell separated into a first compartment with electrodes for reducing water to hydrogen and a second compartment separate from the first compartment with electrodes for producing oxygen.

7. The system of claim 6 , wherein a plurality of electrolytic cells are connected together in series or parallel within the wellbore.

8. 10. The system of claim 1, further comprising a pressure regulator adapted to control a pressure of at least one of the produced hydrogen or oxygen in one of the hydrogen tubing strings or the oxygen tubing strings.

9. providing a well from the surface to a subsurface formation; installing at least one electrolyzer in said well; providing a supply power to the at least one electrolyser; providing a feed water to the at least one electrolyzer; Producing hydrogen gas in the electrolyzer; collecting and transporting the produced hydrogen gas to the surface; A method for producing hydrogen, comprising:

10. 10. The method of claim 9, wherein the supply power is transported from the surface to the at least one electrolyzer via a power supply cable extending therebetween.

11. 10. The method of claim 9, wherein the feed water is transported from the surface to the at least one electrolyzer via a supply tubing string extending therebetween.

12. The method of claim 11 , wherein the feed water is introduced into the supply tubing string at high pressure.

13. The method of claim 11 , wherein the feed water is introduced into the supply tubing string at an elevated temperature.

14. 10. The method of claim 9, further comprising transporting produced hydrogen in at least one collection tubing string extending from the at least one electrolyzer to the surface.

15. 15. The method of claim 14, further comprising controlling the surface production of hydrogen and / or oxygen from each tubing string to maintain the gas in each tubing string at a desired pressure.

16. 10. The method of claim 9, further comprising utilizing underground wells as structural support for storing produced hydrogen prior to transport to the surface.

17. 10. The method of claim 9, wherein the pressure of the produced hydrogen gas and oxygen gas in each tubing string is allowed to build up until it reaches a desired pressure up to, but not exceeding, the maximum underground storage pressure of the tubing string.

18. 10. The method of claim 9, further comprising determining a hottest location within the well and installing the at least one electrolyzer at the hottest location.

19. The method of claim 9 , further comprising the step of installing the at least one electrolyzer in a deepest portion of the wellbore.

20. The method of claim 9 , wherein the well is selected to be an oil reservoir after a steam recovery process or a heat recovery process.

21. The method of claim 9 , wherein the produced hydrogen is passed through a fuel cell to generate electrical power.

22. 10. The method of claim 9, wherein produced water is injected into a well and supplied to the electrolyzer.

23. 10. The method of claim 9, wherein the produced hydrogen is combusted to generate at least one of power, heat, and steam.

24. 10. The method of claim 9, wherein produced water or condensed steam is injected into the well and supplied to the electrolyzer.

25. 10. The method of claim 9, wherein the power used by the electrolyzer is provided from at least one of a solar photovoltaic cell, wind, hydroelectric, nuclear, and a fuel-powered generator.

26. 10. The method of claim 9, wherein at least one of the oxygen and hydrogen produced is passed through a turbine generator to produce at least one of rotational energy and electrical power.

27. 10. The method of claim 9, wherein hydrogen is reduced from water in a first compartment using electrodes for reducing water to hydrogen, and oxygen is produced from water in a second compartment located separately from the first compartment using electrodes electrically connected to the electrodes of the first compartment.

28. 10. The method of claim 9, wherein the water in the electrolyzer is at hydrostatic pressure at a submerged depth of the electrolyzer.

29. 10. The method of claim 9, wherein the produced oxygen and hydrogen are under pressure in the electrolyzer and are sent to respective production tubing strings connected to the electrolyzer and to the surface.

30. 1. A method for producing hydrogen from an underground system, comprising: providing a well from the surface to the subsurface; installing at least one electrolyzer at one or more depths within said well; supplying water to the electrolyser via a connection; supplying an electric current to the electrolyzer to produce oxygen and hydrogen; separating the produced oxygen and hydrogen and filling at least one hydrogen tubing string and at least one oxygen tubing string to a desired pressure; separately producing gas from said tubing string at a desired target pressure at the surface; The following process: passing at least one of the high pressure oxygen and hydrogen through a turbine to generate rotational energy; passing at least one of the high pressure oxygen or hydrogen through a turbine and a generator to generate electricity; Supplying the produced hydrogen to a combustion engine and combusting it to obtain rotational energy; providing hydrogen to a combustor to obtain heat; and supplying said hydrogen to a fuel cell to generate electrical power; generating energy through at least one of providing water produced from the energy generating step for supplying to said electrolyser; delivering the high pressure oxygen at a desired pressure to said above-ground storage vessel for storage or transportation; delivering the high pressure hydrogen at a desired pressure to said above-ground storage vessel for storage or transportation; A method comprising:

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