System for generating electricity or hydrogen from natural gas

Abstract

A system for generating electricity or hydrogen from natural gas may be connected between a gas trunk pipe and a local gas distribution pipe. The system includes a thermal energy storage unit containing a thermal energy storage material heated by an energy source. The system also includes a heat exchanger in fluid communication with the thermal energy storage unit, the heat exchanger receiving flowing natural gas from the gas trunk and heated fluid from the thermal energy storage unit for heating the natural gas stream. The system also includes an expander in fluid communication with the heat exchanger, and the expander receives the heated natural gas stream from the heat exchanger and expands the heated natural gas stream to cool the heated natural gas stream and reduce its pressure. A generator connected to the expander generates electrical power by expanding the heated natural gas stream via the expander.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] Any and all applications claiming foreign or domestic priority identified in the Application Data Sheet filed with this application are incorporated herein by reference pursuant to 37 CFR 1.57. This application claims priority to U.S. Provisional Patent Application No. 63 / 363,232 filed on April 19, 2022, the entire contents of which are incorporated herein by reference and are considered part of the specification. Technical Field

[0003] The present invention relates to green energy source generation, and more particularly to systems and methods for generating electricity or hydrogen from natural gas using renewable energy sources. Background Art

[0004] Natural gas is a non-renewable energy source and a widely used fossil fuel (e.g., for heating, cooking, to generate electricity). There is a growing interest in reducing the use of fossil fuels to reduce greenhouse gas emissions into the atmosphere. Summary of the invention

[0005] There is a need for systems and methods that reduce the use of natural gas in generating electricity.

[0006] According to one aspect of the present disclosure, a system is provided for heating and expanding natural gas between a gas main and local gas distribution pipes to generate electricity or produce hydrogen to capture energy that would otherwise be lost as entropy by expanding the gas between the gas main and the local gas distribution pipes via a valve (e.g., a throttle valve).

[0007] In certain aspects, the technology described herein relates to a system for generating electricity or hydrogen from natural gas, the system being configured to be connected to a gas main and a local gas distribution pipe. The system includes a thermal energy storage unit, the thermal energy storage unit containing a thermal energy storage material, the thermal energy storage unit being configured to receive energy from an energy source to heat the thermal energy storage material. The system also includes a heat exchanger in fluid communication with the thermal energy storage unit, the heat exchanger being configured to receive flowing natural gas from the gas main and a heated fluid from the thermal energy storage unit, the heated fluid heating the natural gas stream. The system also includes an expander in fluid communication with the heat exchanger, the expander being configured to receive a heated natural gas stream from the heat exchanger, and being configured to expand the heated natural gas stream to cool the heated natural gas and reduce its pressure. The system also includes a generator connected to the expander and configured to generate electricity by expanding the heated natural gas stream via the expander.

[0008] In certain aspects, the technology described herein relates to a system in which a thermal energy storage unit, a heat exchanger, an expander, and a generator are part of a self-contained transportable unit.

[0009] In certain aspects, the technology described herein relates to a system in which the energy source is a renewable energy source.

[0010] In certain aspects, the technology described herein relates to a system in which the energy source is a photovoltaic power plant.

[0011] In certain aspects, the technology described herein relates to a system in which the energy source is a concentrated solar power plant.

[0012] In certain aspects, the technology described herein relates to a system in which the energy source is an electrical grid.

[0013] In certain aspects, the technology described herein relates to a system in which the thermal energy storage material is water.

[0014] In certain aspects, the technology described herein relates to a system in which the thermal energy storage material is pressurized water.

[0015] In certain aspects, the technology described herein relates to a system in which the thermal energy storage material includes a solid material.

[0016] In certain aspects, the technology described herein relates to a system in which the thermal energy storage material includes rock.

[0017] In certain aspects, the technology described herein relates to a system wherein the thermal energy storage material comprises packed gravel.

[0018] In certain aspects, the technology described herein relates to a system wherein the dilator includes a first dilator and a second dilator.

[0019] In certain aspects, the technology described herein relates to a system wherein a heat exchanger includes a first heat exchanger located between a gas trunk and a first expander and a second heat exchanger located between the first expander and a second expander.

[0020] In certain aspects, the technology described herein relates to a system that further includes an electrolyzer configured to receive the generated electricity from the generator to generate hydrogen.

[0021] In certain aspects, the technology described herein relates to a system in which generated hydrogen gas is injected into a local gas distribution tube.

[0022] In certain aspects, the technology described herein relates to a system in which generated hydrogen gas is injected into a tube separate from a local gas distribution tube.

[0023] In certain aspects, the technology described herein relates to a system in which generated electricity is supplied to a grid.

[0024] In certain aspects, the technology described herein relates to a method for generating electricity or hydrogen from natural gas. The method includes heating a natural gas stream flowing between a gas main pipe and a local gas distribution pipe via a heat exchanger. The method also includes expanding the heated natural gas stream received from the heat exchanger via an expander. The method also includes generating electricity by expanding the heated natural gas stream via the expander.

[0025] In certain aspects, the technology described herein relates to a method in which heating a natural gas stream includes receiving a heated fluid from a thermal energy storage unit in a heat exchanger to heat the natural gas stream.

[0026] In certain aspects, the technology described herein relates to a method in which expanding a heated natural gas stream includes cooling and reducing the pressure of the heated natural gas stream.

[0027] In certain aspects, the technology described herein relates to a method in which expanding a heated natural gas stream occurs in multiple stages.

[0028] In certain aspects, the technology described herein relates to a method that includes generating hydrogen via an electrolyzer powered by generated electricity.

[0029] In certain aspects, the technology described herein relates to a method that includes injecting generated hydrogen gas into a local gas distribution tube.

[0030] In certain aspects, the technology described herein relates to a method that includes injecting generated hydrogen gas into a tube separate from a local gas distribution tube.

[0031] In certain aspects, the technology described herein relates to a method that includes supplying at least a portion of generated electricity to a power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a system for generating electricity from natural gas.

[0033] Figure 2 is a schematic diagram of another system for generating electricity from natural gas.

[0034] Figure 3 is a schematic diagram of a stand-alone system for generating electricity from natural gas.

[0035] Figure 4 is a schematic diagram of a stand-alone system for producing hydrogen from natural gas.

[0036] Figure 5 is a schematic diagram of a stand-alone system for generating electricity from natural gas.

[0037] Figure 6 is a schematic diagram of a stand-alone system for generating hydrogen from natural gas. DETAILED DESCRIPTION

[0038] Figure 1 A system 100 for utilizing natural gas to generate electricity or hydrogen is shown. Natural gas (e.g., a hydrocarbon gas mixture including methane) is transported from a source to a city or industrial site via a gas pipe trunk 10 at a pressure ranging from about 25 bar to about 100 bar (e.g., about 363 Psi to about 1450 Psi, 75 bar, or 1087 Psi). Natural gas is transmitted from the gas pipe trunk 10 to a local distribution pipe 90 via a connecting pipe 93, wherein a valve 95 (e.g., a throttle valve) is connected to the connecting pipe 93. The valve 95 can be actuated (e.g., throttled) to reduce the pressure of the natural gas in the local distribution pipe 90 to a lower pressure, such as about 5 bar (e.g., about 73 Psi). The local distribution pipe 90 can be connected to a gas delivery pipe (not shown) that delivers natural gas to homes and commercial and industrial sites.

[0039] In one embodiment, the system 100 advantageously uses a portion (e.g., 5%) of the natural gas flowing through the gas pipeline trunk 10 to generate electricity using a renewable energy source in one example, and supplies electricity to a power grid or to a power storage device (e.g., a battery). As discussed further below, in another embodiment, the system 100 advantageously uses a portion (e.g., 5%) of the natural gas flowing through the gas pipeline trunk 10 to generate hydrogen using a renewable energy source in one example, and supplies the generated hydrogen. As described below, in other embodiments, electricity from the grid is used instead of a renewable energy source to generate electricity or generate hydrogen.

[0040] The system 100 includes a thermal energy storage unit 20 that can store thermal energy. In one embodiment, the thermal energy storage unit 20 can contain a liquid thermal energy storage material (e.g., water, pressurized water). In another embodiment, the thermal energy storage unit 20 can contain a solid thermal energy storage material (e.g., rock, gravel packed bed). The thermal energy storage unit 20 can receive heat or energy from an energy source 30 to heat the thermal energy storage material to a temperature between, for example, about 100° C. and about 160° C. (including 100° C. and 160° C.). In one embodiment, the energy source 30 is a power grid that delivers electricity to the thermal energy storage unit 20 (e.g., to a resistor in the thermal energy storage unit 20 to heat the thermal energy storage material). In another embodiment, the energy source 30 is a renewable energy source (e.g., a solar (e.g., photovoltaic or PV) energy source or a wind energy source) that provides power to, for example, a resistive heater (e.g., an electrical resistor) in the thermal energy storage unit 20, which can heat the thermal energy storage material. In another embodiment, the renewable energy source may be a concentrated solar energy source (eg, concentrated solar power or CSP) that delivers heated air or heated liquid to the thermal energy storage unit 20 to heat the thermal energy storage material.

[0041] The thermal energy storage unit 20 is connected to the heat exchanger 40 via the pipe 22. In the case where the thermal energy storage material is water, the thermal energy storage unit 20 supplies heated water to the heat exchanger 40 via the pipe 22. In the case where the thermal energy storage material is solid (e.g., rock, packed gravel), the thermal energy storage unit 20 supplies heated air to the heat exchanger 40 via the pipe 22. The heat exchanger 40 is connected to the gas pipeline trunk 10 via the pipe 42. The pipe 42 guides a certain amount of natural gas (e.g., between 5% and 10% of the volume supplied through the gas pipeline trunk 10, inclusive) from the gas pipeline trunk 10 to the heat exchanger 40, where the natural gas is heated by the heated fluid supplied by the thermal energy storage unit 20.

[0042] The heated natural gas leaves the heat exchanger 40 via pipe 44, which directs the heated natural gas to an expander 50 (e.g., a turbine), which expands the heated natural gas to cool the gas, and the cooled gas is supplied to the local distribution pipe 90 via pipe 52, at the nominal pressure of the natural gas in the local distribution pipe 90 (e.g., the nominal pressure is 5 bar, between 4.8 bar and 5.2 bar, etc.). In one embodiment, the expander 50 is a single-stage expander (e.g., a single-stage turbine). In another embodiment discussed further below, the expander 50 can be a two-stage expander (e.g., a two-stage turbine). The expander 50 is connected (e.g., the output shaft of the expander 50 is connected) to a generator 60 (e.g., an electric generator), wherein the expansion of the natural gas by the expander 50 (e.g., a turbine) generates electricity via the generator 60. In one embodiment, the electricity generated by the generator 60 is supplied to a power grid. In another embodiment, as discussed further below, the electricity generated by the generator 60 is supplied to an electrolyzer to generate hydrogen. In one embodiment, the generator 60 can be a synchronous generator (e.g., can rotate at 3600 rpm to synchronize with the grid), and the expander 50 can rotate at 5000 rpm or 6000 rpm (e.g., with a gearbox in between). In another embodiment, where the system 100 is used to generate hydrogen via an electrolyzer (as discussed further below), the generator can be a DC generator (e.g., a 0.5 MW generator) rotating at 10,000 rpm or 20,000 rpm, and operated with the expander 50 rotating at 20,000 rpm, where the DC generator can be connected to the electrolyzer via a DC-DC converter, and the energy source supplying energy to the thermal energy storage unit 20 can be a renewable energy source (e.g., a photovoltaic power plant) providing 1 MW or 2 MW.

[0043] Figure 2 A system 100' is shown for utilizing natural gas to generate electricity or hydrogen. Some features of the system 100' are similar to Figure 1 Therefore, the reference numerals used to represent the various components of the system 100' are the same as those used to identify the various components of the system 100'. Figure 1 The corresponding components of the system 100 in FIG. 1 are labeled the same. Figure 1 The structure and description of the various features and components of the system 100 and the manner in which they are operated and controlled should be understood to also apply to Figure 2 The corresponding features and components of system 100' in FIG. 1 are the same as those described below, except as described below.

[0044] System 100' differs from system 100 in that system 100' includes a two-stage expander (e.g., a first expander 50A and a second expander 50B, such as a two-stage turbine) and two heat exchangers (e.g., a first heat exchanger 40A and a second heat exchanger 40B) and two generators (e.g., a first generator 60A and a second generator 60B) or an optional single generator (e.g., generator 60). Pipe 42A connects the gas pipeline trunk 10 with the first heat exchanger 40A to guide the natural gas into the heat exchanger 40A, where the natural gas is heated by the heated fluid (e.g., heated air, heated water) from the thermal energy storage unit 20. The heated natural gas leaves the first heat exchanger 40A via pipe 44A and flows to the first expander 50A, where the heated natural gas is expanded and cooled. The first expander 50A is connected (e.g., via an output shaft) to a first generator 60A, which generates electricity due to the expansion of natural gas through the first expander 50A. The cooled natural gas leaves the first expander 50A via pipe 42B and is directed to the second heat exchanger 40B, where the natural gas is heated by a heated fluid (e.g., heated air, heated water) from the thermal energy storage unit 20. The heated natural gas leaves the second heat exchanger 40B via pipe 44B and flows to the second expander 50B, where the heated natural gas is expanded and cooled. The second expander 50B is connected (e.g., via an output shaft) to a second generator 60B, which generates electricity due to the expansion of natural gas through the second expander 50B. Alternatively, the expanders 50A, 50B are both connected to a single generator (e.g., generator 60, as shown in FIG. 1 ). Figure 5-Figure 6 5B) rather than two separate generators 60A, 60B. The heated natural gas leaves the second expander 50B, which expands the heated natural gas to cool the gas, and the cooled gas is supplied to the local distribution pipe 90 via pipe 52 at the nominal pressure of the natural gas in the local distribution pipe 90 (e.g., a nominal pressure of 5 bar, between 4.8 bar and 5.2 bar, etc.). In another embodiment, as discussed further below, the electricity generated by the generators 60A, 60B is supplied to an electrolyzer to generate hydrogen.

[0045] Advantageously, the use of two stages of expanders (e.g., expander 50A and expander 50B, with reheating in between using heat exchanger 40B) in system 100' advantageously allows system 100' to reduce the pressure drop between each stage, which facilitates the design of thermal energy storage unit 20 and the thermal energy storage material used. For example, in the case where the gas trunk 10 operates at a pressure of 100 bar and the local gas distribution pipe 90 operates at a nominal pressure of 5 bar, having two stages of expansion allows the first expander 50A to reduce the pressure of the natural gas from 100 bar to about 20 bar, and allows the second expander 50B to reduce the pressure of the natural gas from 20 bar to 5 bar. Advantageously, the two-stage expansion allows the thermal energy storage material to have a temperature between 100°C and 160°C (e.g., 120°C) for the fluid supplied to the heat exchangers 40A, 40B, which allows water (e.g., pressurized water of about 3-6 bar, such as in a boiler) to be used as the thermal energy storage material. In such embodiments, the thermal energy storage unit 20 can be of simplified design (e.g., a boiler for pressurized water), allowing the system 100, 100', 100A-100D to be supplied as a package system or a stand-alone system. In contrast, when a single state expansion is used in the system, a drop from 100 bar to 5 bar via the expander would require the thermal energy storage material to have a temperature of about 300°C for the fluid supplied to the heat exchanger.

[0046] Figure 3 A system 100A is shown that utilizes natural gas to generate electricity. Some features of the system 100A are similar to Figure 1 Therefore, the reference numerals used to represent the various components of system 100A are the same as those used to identify the various components of system 100A. Figure 1 The corresponding components of the system 100 in FIG. 1 are labeled the same. Figure 1 The structure and description of the various features and components of the system 100 and the manner in which they are operated and controlled are understood to also apply to Figure 3 The corresponding features and components of system 100A in , except as described below.

[0047] System 100A differs from system 100 in that system 100A is optionally a stand-alone system that can be contained in container 2A or attached to a frame. System 100A can be advantageously transported (e.g., in container 2A) to a location where system 100A can be connected to a gas pipe trunk and local gas distribution pipes (e.g., such as gas pipe trunk 10 and local gas distribution pipe 90). In one example, multiple systems 100A can be transported to different locations in a geographic area (e.g., outside a city or county) where an existing gas distribution network exists, each of which is connected to a gas pipe trunk and a local gas distribution pipe, thereby advantageously providing energy resilience (e.g., multiple systems 100A can be operated with scheduled or unscheduled maintenance required).

[0048] The system 100A can be connected to a gas pipeline trunk (e.g., a gas pipeline trunk 10 operating at a relatively high delivery pressure (e.g., 25-100 bar)) via a connector 41 to direct a portion of the natural gas to flow through the gas pipeline trunk to the heat exchanger 40 and then to the expander 50. The system 100A in the container 2A can be connected to a local distribution pipe (e.g., local distribution pipe 90) via a connector 53 to return the portion of the natural gas in an expanded state and at a relatively low pressure (e.g., 5 bar nominal pressure). The system 100A can also have a connection 31, in one example, electrical energy (e.g., from a photovoltaic power plant, from the grid) is provided to the thermal energy storage unit 20 via the connection to heat (e.g., via a resistance heater) the thermal energy storage material therein, wherein the thermal energy storage unit 20 then supplies the heated fluid (e.g., heated air, hot water, hot pressurized water) to the heat exchanger 40 to heat the portion of the natural gas. In another embodiment, in one example, the connection 31 is a connection through which, in one example, a heated fluid (e.g., heated air, heated water, such as from a concentrated solar power plant) is provided to the thermal energy storage unit 20, which then supplies the heated fluid (e.g., heated air, hot water, hot pressurized water) to the heat exchanger 40 to heat the portion of the natural gas. The system 100A can have an electrical connection 70 through which the electricity generated by the generator 60 can be supplied to the outside of the container 2A (e.g., to the grid, to an energy storage unit such as a battery, etc.).

[0049] Figure 4 A system 100B is shown for generating hydrogen using natural gas. Some features of the system 100B are similar to those based on Figure 1 100 of the systems Figure 3 Therefore, the reference numerals used to identify the various components of system 100B are the same as those used to identify the various components of system 100B. Figure 3The corresponding components of the system 100A in FIG. 1 are labeled the same. Figure 1 The structure and description of the various features of the system 100 Figure 3 The structure and description of the various features and components of the system 100A and the manner in which they are operated and controlled are understood to also apply to Figure 4 The corresponding features and components of system 100B in , except as described below.

[0050] System 100B is different from system 100A in that generator 60 supplies electricity to electrolyzer 80 to generate hydrogen, and the hydrogen can leave system via pipe and / or connector 81.Electrolyzer 80 can be a conventional electrolyzer (for example, using potassium hydroxide, alkaline electrolyzer) that produces hydrogen under a pressure of, for example, 16bar to 30bar.System 100B is alternatively an independent system, which can be contained in container 2B or attached to a framework.System 100B can advantageously be transported (for example, in container 2B) to a certain position, where system 100B can be connected to gas pipe trunk and local gas distribution pipe (for example, such as gas pipe trunk 10 and local gas distribution pipe 90).In one embodiment, the hydrogen generated can be supplied to container in the form of compression or pressurization, and then the hydrogen can be transported.In another embodiment, the hydrogen generated can be injected into a pipeline parallel to a local gas distribution pipe (for example, pipe 90). In yet another embodiment, the generated hydrogen can be directly injected into the local gas distribution pipe (e.g., pipe 90) and can account for, for example, 5-10% of the flow through the local gas distribution pipe, thereby advantageously reducing greenhouse gas emissions of the distributed gas. In one embodiment, where the energy source providing electricity or heated fluid (e.g., heated air, heated water) to the thermal energy storage unit 20 is a renewable energy source (e.g., a photovoltaic power plant, a concentrated solar energy power plant), the hydrogen generated by the electrolyzer 80 will be green hydrogen.

[0051] Figure 5 A system 100C is shown that utilizes natural gas to generate electricity. Some features of the system 100C are similar to Figure 2 Therefore, the reference numerals used to represent the various components of system 100C are the same as those used to identify Figure 2 The corresponding parts of the system 100' in FIG. 1 have the same reference numerals. Figure 2 The structure and description of the various features and components of the system 100' and the operation and control thereof are understood to also apply to Figure 5 The corresponding features and components of system 100C in , except as described below.

[0052] The system 100C differs from the system 100' in that the system 100C is optionally a stand-alone system that can be housed in a container 2C or attached to a frame. The system 100C can be advantageously transported (e.g., in a container 2C) to a location where it can be connected to a gas pipe trunk and local gas distribution pipes (e.g., such as the gas pipe trunk 10 and the local gas distribution pipe 90).

[0053] In one example, multiple systems 100C can be transported to different locations in a geographic area where a gas distribution network exists (e.g., outside a city or county), with each system connected to a gas pipe trunk and local gas distribution pipes, thereby advantageously providing energy resilience (e.g., multiple systems 100C can be operated with or without the need for scheduled or unscheduled maintenance).

[0054] The system 100C can be connected to a gas main (e.g., a gas main 10 operating at a relatively high delivery pressure (e.g., 25-100 bar) via a connector 41 to direct a portion of the natural gas to flow through the gas main to the heat exchanger 40A and then to the expander 50A, as previously discussed. The system 100C in the container 2C can be connected to a local distribution pipe (e.g., local distribution pipe 90) via a connector 53 to return the portion of the natural gas in an expanded state and at a relatively low pressure (e.g., 5 bar nominal pressure). The system 100C can also have a connection 31, in one example, electrical energy (e.g., from a photovoltaic power plant, from the grid) is provided to the thermal energy storage unit 20 via the connection to heat (e.g., via a resistive heater) the thermal energy storage material therein, wherein the thermal energy storage unit 20 then supplies the heated fluid (e.g., heated air, hot water, hot pressurized water) to the heat exchangers 40A, 40B to heat the portion of the natural gas. In another embodiment, the connection 31 is a connection through which, in one example, a heated fluid (e.g., heated air, heated water, such as from a concentrated solar power plant) is provided to the thermal energy storage unit 20, which then supplies the heated fluid (e.g., heated air, hot water, hot pressurized water) to the heat exchangers 40A, 40B to heat the portion of the natural gas. The system 100C can have an electrical connection 70 through which electricity generated by the generator 60 (which is connected to the expanders 50A, 50B) can be supplied to the outside of the container 2C (e.g., to the grid, to an energy storage unit such as a battery, etc.).

[0055] Figure 6 A system 100D is shown for generating hydrogen using natural gas. Some features of the system 100D are similar to those based on Figure 2 The system 100' Figure 5Therefore, the reference numerals used to identify the various components of system 100D are the same as those used to identify the various components of system 100D. Figure 5 The corresponding components of the system 100C in FIG. 100B have the same reference numerals. Figure 2 The structure and description of the various features of the system 100' Figure 5 The structure and description of the various features and components of the system 100C and the manner in which they are operated and controlled are understood to also apply to Figure 6 The corresponding features and components of system 100D in FIG. 10A , except as described below.

[0056] System 100D is different from system 100C in that generator 60 supplies electricity to electrolyzer 80 to generate hydrogen, and the hydrogen can leave the system via pipe and / or connector 81.Electrolyzer 80 can be a conventional electrolyzer (e.g., using potassium hydroxide, alkaline electrolyzer) that produces hydrogen under a pressure of, for example, 16bar to 30bar.System 100D is optionally an independent system, which can be contained in container 2D or attached to a framework.System 100D can be advantageously transported (e.g., in container 2D) to a certain position, where system 100D can be connected to a gas pipe trunk and a local gas distribution pipe (e.g., such as gas pipe trunk 10 and local gas distribution pipe 90).In one embodiment, the hydrogen generated can be supplied to the container in a compressed or pressurized form, and then the hydrogen can be transported.In another embodiment, the hydrogen generated can be injected into a pipeline parallel to a local gas distribution pipe (e.g., pipe 90). In yet another embodiment, the generated hydrogen can be directly injected into the local gas distribution pipe (e.g., pipe 90) and can account for, for example, 5-10% of the flow through the local gas distribution pipe, thereby advantageously reducing greenhouse gas emissions of the distributed gas (e.g., reducing CO2 emissions). In one embodiment, where the energy source that provides electricity or heated fluid (e.g., heated air, heated water) to the thermal energy storage unit 20 is a renewable energy source (e.g., a photovoltaic power plant, a concentrated solar energy power plant), the hydrogen generated by the electrolyzer 80 will be green hydrogen.

[0057] Advantageously, the systems 100, 100', 100A-100D allow for separation of heat sources (in terms of origin and time) to generate electricity or hydrogen. For example, in the case of supplying electricity (e.g., 1 KWh) to the thermal energy storage unit 20 to heat the thermal energy storage material therein, such electricity may be provided from a renewable source (e.g., a photovoltaic power plant) over a period of time (e.g., 4 hours), or may be provided from the grid (e.g., by bidding or reducing the price of electricity from the grid over a set period of time), and heat from the thermal energy storage unit 20 may be provided to the heat exchanger 40, 40A, 40B over a different and / or extended period of time that is not connected to the period of time during which the electricity is delivered to the thermal energy storage unit 20. In one example, during weekends when demand for natural gas is low (e.g., from industry), electricity can be supplied to the thermal energy storage unit 20, and the thermal energy storage unit 20 can thereafter supply stored heat to the heat exchangers 40, 40A, 40B to heat the natural gas flowing through the system 100, 100', 100A-100D over the next few days or a week. The thermal energy storage unit 20 (e.g., storing water or rock or gravel as the thermal energy storage material) can be relatively large and inexpensive to provide heat to the heat exchangers 40, 40A, 40B over a few days or a week. Thus, in one embodiment, the system 100, 100', 100A-100D can be used to provide a base load of energy (e.g., a base amount of electricity or a base amount of hydrogen), which can be provided, for example, 24 hours a day, seven days a week.

[0058] In one embodiment, the amount of electricity or hydrogen generated by the system 100, 100', 100A-100D can be adjusted as needed (e.g., so that the nominal gas pressure in the local gas distribution pipe is about 5 bar, but varies between 4.8 bar and 5.2 bar). Advantageously, the system 10, 100', 100A-100D improves the efficiency of the gas pipeline by heating and expanding the natural gas (e.g., via the heat exchanger 40, 40A, 40B and the expander 50, 50A, 50B). For example, for every 1KWh supplied to the thermal energy storage unit 20 (e.g., used to heat the thermal energy storage material therein, which is then supplied to the heat exchanger), more than 1KWh (e.g., 1.5, 1.7, 2.0KWh) is generated by the expansion of the heated gas (e.g., via the expander 50, 50A, 50B). Furthermore, due to the efficiency of the system 100, 100', 100A-100D (e.g., it is at least about 150%), less energy may need to be supplied to the thermal energy storage unit 20. For example, in the case where a renewable energy source is used to heat the thermal energy storage unit 20, such as a photovoltaic power plant or a concentrated solar power plant, the solar energy field of the power plant may be smaller.

[0059] Additional Embodiments

[0060] In an embodiment of the present invention, the system and method for generating electricity or hydrogen from natural gas may comply with any of the following clauses:

[0061] Clause 1. A system for generating electricity or hydrogen from natural gas, the system being configured to be connected to a gas main and local gas distribution pipes, the system comprising:

[0062] a thermal energy storage unit comprising a thermal energy storage material, the thermal energy storage unit being configured to receive energy from an energy source to heat the thermal energy storage material;

[0063] a heat exchanger in fluid communication with the thermal energy storage unit, the heat exchanger being configured to receive flowing natural gas from the gas trunk and heated fluid from the thermal energy storage unit, the heated fluid heating the natural gas flow;

[0064] an expander in fluid communication with the heat exchanger, the expander being configured to receive the heated natural gas stream from the heat exchanger and being configured to expand the heated natural gas stream to cool the heated natural gas stream and reduce its pressure; and

[0065] A generator is connected to the expander and is configured to generate electricity by expanding the heated natural gas flow through the expander.

[0066] Clause 2. A system according to clause 1, wherein the thermal energy storage unit, heat exchanger, expander and generator are part of an independent transportable unit.

[0067] Clause 3. A system according to any of clauses 1-2, wherein the energy source is a renewable energy source.

[0068] Clause 4. The system of any of Clauses 1-3, wherein the energy source is a photovoltaic power plant.

[0069] Clause 5. A system according to any one of clauses 3, wherein the energy source is a concentrated solar power plant.

[0070] Clause 6. A system according to any of Clauses 1-3, wherein the energy source is an electric power grid.

[0071] Clause 7. The system of any of Clauses 1-6, wherein the thermal energy storage material is water.

[0072] Clause 8. The system of any of Clauses 1-7, wherein the thermal energy storage material comprises pressurized water.

[0073] Clause 9. The system of any of Clauses 1-6, wherein the thermal energy storage material comprises a solid material.

[0074] Clause 10. The system of any of Clauses 1-6 and 9, wherein the thermal energy storage material comprises rock.

[0075] Clause 11. The system of any of Clauses 1-6 and 9-10, wherein the thermal energy storage material comprises packed gravel.

[0076] Clause 12. The system of any of Clauses 1-11, wherein the dilator comprises a first dilator and a second dilator.

[0077] Clause 13. The system of any one of Clauses 1-12, wherein the heat exchanger comprises a first heat exchanger located between the gas trunk and a first expander and a second heat exchanger located between the first expander and a second expander.

[0078] Clause 14. The system of any one of Clauses 1-13, further comprising an electrolyzer configured to receive the generated electricity from the generator to generate hydrogen.

[0079] Clause 15. The system of clause 14, wherein the generated hydrogen gas is injected into the local gas distribution pipe.

[0080] Clause 16. The system of Clause 14, wherein the generated hydrogen gas is injected into a tube separate from the local gas distribution tube.

[0081] Clause 17. The system of any of Clauses 1-13, wherein the generated electricity is supplied to a power grid.

[0082] Clause 18. A method for generating electricity or hydrogen from natural gas, the method comprising:

[0083] heating a natural gas stream flowing between a gas main pipe and local gas distribution pipes via a heat exchanger;

[0084] expanding a heated natural gas stream received from the heat exchanger via an expander; and

[0085] Electricity is generated by expanding a heated natural gas flow through the expander.

[0086] Clause 19. The method of Clause 18, wherein heating the natural gas stream comprises receiving a heated fluid from a thermal energy storage unit in the heat exchanger to heat the natural gas stream.

[0087] Clause 20. The method of any of Clauses 18-19, wherein expanding the heated natural gas stream comprises cooling and reducing the pressure of the heated natural gas stream.

[0088] Clause 21. The method of any of Clauses 18-20, wherein expanding the heated natural gas stream occurs in a plurality of stages.

[0089] Clause 22. The method of any one of Clauses 18-21, further comprising generating hydrogen via an electrolyzer powered by the generated electricity.

[0090] Clause 23. The method of clause 22, further comprising injecting generated hydrogen into the local gas distribution pipe.

[0091] Clause 24. The method of Clause 22, further comprising injecting the generated hydrogen gas into a tube separate from the local gas distribution tube.

[0092] Clause 25. The method of any of Clauses 18-24, further comprising supplying at least a portion of the generated electricity to a power grid.

[0093] Although certain embodiments of the present invention have been described, these embodiments are presented only by way of example and are not intended to limit the scope of the present disclosure. In fact, the novel methods and systems described herein may be embodied in various other forms. In addition, various omissions, substitutions, and changes may be made to the systems and methods described herein without departing from the spirit of the present disclosure. The attached claims and their equivalents are intended to cover such forms or modifications that fall within the scope and spirit of the present disclosure. Therefore, the scope of the present invention is limited only by reference to the attached claims.

[0094] Features, materials, characteristics or groups described in conjunction with a particular aspect, embodiment or example should be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification, unless incompatible therewith. All features disclosed in this specification (including any accompanying claims, abstract and drawings) and / or all steps of any method or process so disclosed may be combined in any combination, except that at least some of such features and / or steps are mutually exclusive combinations. This protection is not limited to the details of any foregoing embodiments. This protection extends to any novel feature or any novel combination of features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel step or any novel combination of steps of any method or process so disclosed.

[0095] In addition, certain features described in the present disclosure in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination. In addition, although features may be described above as functioning in certain combinations, in some cases, one or more features from a claimed combination may be deleted from the combination, and the combination may be claimed as a sub-combination or a variation of a sub-combination.

[0096] In addition, although the operations may be shown in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in a sequential order, or all operations need not be performed to achieve the desired results. Other operations not depicted or described may be incorporated into the example methods and processes. For example, one or more additional operations may be performed before, after, simultaneously or between any of the operations. In addition, in other embodiments, the operations may be rearranged or reordered. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the illustrated and / or disclosed processes may be different from the steps shown in the drawings. Depending on the embodiment, some of the above steps may be removed and other steps may be added. In addition, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. In addition, the separation of the various system parts in the above-mentioned embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described components and systems may generally be integrated together in a single product or packaged into multiple products.

[0097] For purposes of the present disclosure, certain aspects, advantages, and novel features are described herein. Not all such advantages may be achieved according to any particular embodiment. Thus, for example, one skilled in the art will recognize that the present disclosure may be embodied or performed in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages that may be taught or suggested herein.

[0098] Unless specifically stated otherwise or understood otherwise within the context of use, conditional language such as "can," "might," "might," or "may" is generally intended to convey that some embodiments include and other embodiments do not include certain features, elements, and / or steps. Thus, such conditional language is generally not intended to imply that one or more embodiments require features, elements, and / or steps in any way, or that one or more embodiments must include logic for deciding, with or without user input or prompting, whether such features, elements, and / or steps are included or will be performed in any particular embodiment.

[0099] Unless specifically stated otherwise, conjunction language, such as the phrase "at least one of X, Y, and Z," is generally understood with the context in which it is used to convey that a certain item, term, etc. may be X, Y, or Z. Thus, such conjunction language is generally not intended to imply that certain embodiments require the presence of at least one of X, at least one of Y, and at least one of Z.

[0100] Language of degree as used herein, such as the terms "approximately," "about," "roughly," and "substantially" as used herein, refers to a value, amount, or characteristic that is close to a stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms "approximately," "about," "roughly," and "substantially" may refer to an amount within 10%, within 5%, within 1%, within 0.1%, and within 0.01% of the stated amount. As another example, in certain embodiments, the terms "roughly parallel" and "substantially parallel" refer to a value, amount, or characteristic that deviates from exactly parallel by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degrees.

[0101] The scope of the present disclosure is not intended to be limited by the specific disclosure of preferred embodiments in this section or elsewhere in this specification, and may be limited by the claims presented or later presented in this section or elsewhere in this specification. The language of the claims is to be interpreted broadly based on the language used in the claims, and not limited to the examples described in this specification or during the prosecution, which examples are to be interpreted as non-exclusive.

[0102] Of course, the foregoing description is a description of certain features, aspects and advantages of the present invention, and various changes and modifications may be made thereto without departing from the spirit and scope of the present invention. In addition, the device described herein need not have all the purposes, advantages, features and aspects discussed above. Thus, for example, those skilled in the art will recognize that the present invention may be embodied or performed in a manner that realizes or optimizes an advantage or a group of advantages taught herein, without necessarily realizing other purposes or advantages that may be taught or suggested herein. In addition, although multiple variations of the present invention have been shown and described in detail, other modifications and methods of use within the scope of the present invention will be clear to those skilled in the art based on the contents of the present disclosure. It is conceivable that various combinations or sub-combinations may be made to these specific features and aspects of the embodiments, and still fall within the scope of the present invention. Therefore, it should be understood that the various features and aspects of the disclosed embodiments may be combined or substituted with each other to form different modes of the device discussed.

Claims

1. A system for generating electricity or hydrogen from natural gas, the system being configured to be connected to a gas main pipeline and a local gas distribution pipeline, the system comprising: a thermal energy storage unit comprising a thermal energy storage material, the thermal energy storage unit being configured to receive energy from an energy source to heat the thermal energy storage material; a heat exchanger in fluid communication with the thermal energy storage unit, the heat exchanger being configured to receive a natural gas flow from the gas trunk and a heated fluid from the thermal energy storage unit, the heated fluid heating the natural gas flow; an expander in fluid communication with the heat exchanger, the expander being configured to receive the heated natural gas stream from the heat exchanger and being configured to expand the heated natural gas stream to cool the heated natural gas stream and reduce its pressure; and A generator is connected to the expander and is configured to generate electricity by expanding the heated natural gas flow through the expander.

2. The system according to claim 1, wherein: The thermal energy storage unit, heat exchanger, expander and generator are part of an independent transportable unit.

3. The system according to any one of claims 1 to 2, wherein: The energy source is a renewable energy source.

4. The system according to any one of claims 1 to 3, wherein: The energy source is a photovoltaic power station.

5. The system according to any one of claims 1 to 3, wherein: The energy source is a concentrated solar power plant.

6. The system according to any one of claims 1 to 3, wherein: The energy source is the electricity grid.

7. The system according to any one of claims 1 to 6, wherein: The thermal energy storage material is water.

8. The system according to any one of claims 1 to 7, wherein: The thermal energy storage material includes pressurized water.

9. The system according to any one of claims 1 to 6, wherein: The thermal energy storage material comprises a solid material.

10. The system according to any one of claims 1 to 6 and 9, wherein: The thermal energy storage material includes rock.

11. The system according to any one of claims 1-6 and 9-10, wherein: The thermal energy storage material comprises packed gravel.

12. The system according to any one of claims 1 to 11, wherein: The dilator includes a first dilator and a second dilator.

13. The system according to any one of claims 1 to 12, wherein: The heat exchanger includes a first heat exchanger located between the gas trunk pipe and the first expander and a second heat exchanger located between the first expander and the second expander.

14. The system of any one of claims 1-13, further comprising an electrolyzer configured to receive the generated electricity from the generator to generate hydrogen.

15. The system of claim 14, wherein: The generated hydrogen gas is injected into the local gas distribution pipe.

16. The system of claim 14, wherein: The generated hydrogen gas is injected into a pipe separate from the local gas distribution pipe.

17. The system according to any one of claims 1 to 13, wherein: The generated electricity is supplied to the power grid.

18. A method for generating electricity or hydrogen from natural gas, the method comprising: heating a natural gas stream flowing between a gas main pipe and local gas distribution pipes via a heat exchanger; expanding a heated natural gas stream received from the heat exchanger via an expander; and Electricity is generated by expanding the heated natural gas flow through the expander.

19. The method according to claim 18, wherein: Heating the natural gas stream includes receiving a heated fluid from a thermal energy storage unit in the heat exchanger to heat the natural gas stream.

20. The method according to any one of claims 18-19, wherein: Expanding the heated natural gas stream includes cooling and reducing the pressure of the heated natural gas stream.

21. The method according to any one of claims 18 to 20, wherein: Expanding the heated natural gas stream occurs in multiple stages.

22. The method of any one of claims 18-21, further comprising generating hydrogen via an electrolyser powered by the generated electricity.

23. The method of claim 22, further comprising injecting generated hydrogen gas into the local gas distribution pipe.

24. The method of claim 22, further comprising injecting the generated hydrogen gas into a tube separate from the local gas distribution tube.

25. The method of any one of claims 18-24, further comprising supplying at least a portion of the generated electricity to a power grid.

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