Technology configured to enable improved management of fugitive emissions

Abstract

The present invention relates, in various embodiments, to technology configured to enable improved management of fugitive emissions. For example, embodiments include hardware and processes which are applied thereby to manage variable methane content in gas mixtures (particularly those with inert gas content, for example nitrogen, carbon dioxide, argon, and the like), optionally for application in the context of coal mining and other such scenarios. However, it should be noted that the invention has broader application.

Description

TECHNOLOGY CONFIGURED TO ENABLE IMPROVED MANAGEMENT OF FUGITIVE EMISSIONSFIELD OF THE INVENTION

[0001] The present invention relates, in various embodiments, to technology configured to enable improved management of fugitive emissions. For example, embodiments include hardware and processes which are applied thereby to manage variable methane content in gas mixtures (particularly those with inert gas content, for example nitrogen, carbon dioxide, argon, and the like), optionally for application in the context of coal mining and other such scenarios. However, it should be noted that the invention has broader application.BACKGROUND

[0002] Any discussion of the background art throughout the specification should in no way be considered as an admission that such art is widely known or forms part of common general knowledge in the field.

[0003] Fugitive emissions include losses, leaks and other releases of gases such as methane and carbon dioxide (CO2), and are typically associated with the industries extracting and producing natural gas, oil and coal. For example. All coal seams contain some level of gas as a consequence of how the coal is formed. These gases escape (thus becoming fugitive) during both open-cut and underground mining operations.

[0004] Coal mine fugitive emissions often vary in methane content, leading to challenges in the context of emission management. For example, a common approach is “flaring”, whereby fugitive emissions are combusted upon release. Where the ratio of methane to carbon dioxide (CO2) falls below a threshold, flaring can fail. A partial known solution is to add supplementary combustible fuels into low methane content fugitive emissions to ensure continuous flaring.SUMMARY OF THE INVENTION

[0005] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0006] One example embodiment provides a method for management of emissions, the method including: receiving an emissions gas feed from a source, the emissions gas feedincluding a variable ratio of a combustible component and an inert component; providing a control signal to a gas combiner arrangement, wherein the gas combiner arrangement includes: (i) a first input configured to receive the emissions gas feed; (ii) a second input configured to receive a recycled combustible gas feed; (iii) a controller that is responsive to the control signal thereby to meter a rate of flow through the second input; and (iv) an output configured to release provide a combined gas output including a first component derived from the first emissions gas feed and a second component derived from the recycled combustible gas feed wherein the combined gas output has a controlled ratio of a combustible component and an inert component; and providing the combined gas output to a downstream gas processing system; wherein the control signal is defined thereby to operate the controller such that the controlled ratio meets desired attributes.

[0007] One example embodiment provides A system configured for management of emissions, the system including: a feed gas input configured to receive an emissions gas feed from a source, the emissions gas feed including a variable ratio of a combustible component and an inert component; a gas combiner arrangement, wherein the gas combiner arrangement includes: (i) a first input configured to receive the emissions gas feed; (ii) a second input configured to receive a recycled combustible gas feed; (iii) a controller that is responsive to the control signal thereby to meter a rate of flow through the second input; and (iv) an output configured to release provide a combined gas output including a first component derived from the first emissions gas feed and a second component derived from the recycled combustible gas feed, wherein the combined gas output has a controlled ratio of a combustible component and an inert component; and a delivery mechanism for providing the combined gas output to a downstream gas processing system; wherein the controller is operated such that the controlled ratio meets desired attributes.

[0008] Further example embodiments are described below, including in the section entitled “claims”.

[0009] Reference throughout this specification to “one embodiment”, “some embodiments” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment”, “in some embodiments” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures orcharacteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0010] As used herein, unless otherwise specified the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner.

[0011] In the claims below and the description herein, any one of the terms comprising, comprised of or which comprises is an open term that means including at least the elements / features that follow, but not excluding others. Thus, the term comprising, when used in the claims, should not be interpreted as being limitative to the means or elements or steps listed thereafter. For example, the scope of the expression a device comprising A and B should not be limited to devices consisting only of elements A and B. Any one of the terms including orwhich includes orthat includes as used herein is also an open term that also means including at least the elements / features that follow the term, but not excluding others. Thus, including is synonymous with comprising.

[0012] As used herein, the term “exemplary” is used in the sense of providing examples, as opposed to indicating quality. That is, an “exemplary embodiment” is an embodiment provided as an example, as opposed to necessarily being an embodiment of exemplary quality.

[0013] The present invention is not to be limited in scope by any of the specific embodiments described herein. These embodiments are intended for the purpose of exemplification only. Functionally equivalent products, formulations and methods are clearly within the scope of the invention as described herein.

[0014] The invention described herein may include one or more range of values (e.g. size, concentration etc). A range of values will be understood to include all values within the range, including the values defining the range, and values adjacent to the range which lead to the same or substantially the same outcome as the values immediately adjacent to that value which defines the boundary to the range.

[0015] Other definitions for selected terms used herein may be found within the detailed description of the invention and apply throughout. Unless otherwise defined, all otherscientific and technical terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the invention belongs.

[0016] Features of the invention will now be discussed with reference to the following nonlimiting description and examples.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0018] FIG. 1 illustrates a system according to one embodiment.

[0019] FIG. 2A illustrates a method according to one embodiment.

[0020] FIG. 2B illustrates a method according to one embodiment.DETAILED DESCRIPTION

[0021] The present invention relates, in various embodiments, to technology configured to enable improved management of fugitive emissions. For example, embodiments include hardware and processes which are applied thereby to manage variable methane content in gas mixtures (particularly those with inert gas content, for example nitrogen, carbon dioxide, argon, and the like), optionally for application in the context of coal mining and other such scenarios. However, it should be noted that the invention has broader application.

[0022] In overview, embodiments relate to technology whereby the combustible gas component of fugitive emissions is controlled via supplementation with recycled combustible gases (which is in some embodiments derived from the same fugitive emissions source, but may be derived from a separate supply / source which is optionally a combustible has including methane and / or biomethane), thereby to create a flow of gas having desired properties. For example, the desired properties may include a specified target methane content. Preferably, this is operated thereby to enable downstream processing which is reliant on a consistent and / or above threshold combustible content in feed gas, for example to facilitate gas-gas separation, flaring, and so on.

[0023] In a preferred embodiment, an input feed of emissions gas having a variable ratio of combustible component (e.g. methane - CH4) to inert (i.e. non-combustible) component (e.g. carbon dioxide -CO2, nitrogen - N2, and / or Argon) is supplemented based on real-time monitoring thereby to create an output supply of controlled ratio gas (having a controlled ratio of Combustible : Inert) for downstream processing. That downstream processing preferably includes separation, resulting in a supply of gas having comparatively higher combustible (e.g. CH4) content, which is subsequently used for the supplementation of the input feed of emissions gas (i.e. to achieve the controlled ratio).

[0024] The way in which real-time monitoring is performed varies between embodiments. For example, any one or more of the following approaches may be used:• In some embodiments the real-time value is a real-time value representative of the variable ratio in a continuous feed of gas, such that the supplementation involves combining of that continuous flow with additional gas. For example, in some cases an additional container / supply of combustible gas such as methane or biomethane is provided for such a purpose.• In some embodiments the real-time value representative of a ratio of a combustible component to a non-combustible component in a chamber that is supplied by the emissions feed gas, and the supplementation is based on the combustible : inert ratio in that chamber. For example, in some cases the chamber is fed by the emission gas feed only, and combined with a controlled amount from the recycled combustible component upon batch release. In other cases the chamber is fed by the emission gas feed and the recycled combustible component, and released when the controlled ratio is satisfied in the chamber. For example, the chamber may be a surge chamber. It will be appreciated that additional components may be in place to ensure continuous flow of gas downstream of such a chamber (for example such that downstream processing devices are provided with a continuous feed rather than a batched feed).

[0025] FIG. 1 illustrates a system according to one embodiment. It should be appreciated that this is an example only, and that there are various modifications which could be made to the system of FIG. 1 without straying from its core functionalities.

[0026] FIG. 1 illustrates an example emissions source facility 101 , which could by way of example represent a coal mine or other facility. The emissions source is associated with a gasdrainage arrangement, for example a pre-drainage skid or a gas drainage skid. It will be appreciated by those skilled in the art that these are example only in relation to infrastructure for sourcing fugitive emissions, and that a range of alternate approached may be substitutes. Ultimately, what is relevant is that an emissions feed gas source 103 is provided.

[0027] The emissions gas feed gas source 103 is a feed source which includes at least two forms of gasses, defining a variable ratio of a combustible component and an inert component. For the present purposes, the combustible component is assumed to be methane (CH4), or majority CH4, and the inert component is assumed to be carbon dioxide (CO2), or majority CO2. It will be appreciated that the method may be operated in relation to other gases, and that there may also be various impurities present (i.e. the combustible component may be CH4 and / or other combustible gases, and the inert component may be CO2 and / or other inert gases). The variable ratio is dependent on physical characteristics and activities within emissions source 101 , and in some cases affected by operation of drainage arrangement 102.

[0028] Whilst examples below refer to CH4 and CO2, these should be read broadly to cover embodiments referring to “a combustible component which includes CH4” and “an inert component which includes CO2”, and further to embodiments referring to “a combustible component which may or may not include CH4” and “an inert component which may or may not include CO2”. Where there are references to a “controlled ratio” (or a ratio in general), that may be a ratio defined by reference to a threshold proportion of a particular gas substance or combustible / non-combustible component. For example, the “controlled ratio” may be defined as a threshold minimum percentage methane content.

[0029] The emissions gas feed from source 103 is provided to a gas combiner arrangement 110. The gas combiner arrangement includes at least the following components:(i) A first input, presently in the form of an emissions feed gas input 112, which is configured to receive the emissions gas feed from source 103.(ii) A second input, presently in the form of a recycled combustible gas input 113, which is configured to receive a recycled combustible gas feed (in this case being gas with a relatively high CH4 content, generated as discussed further below).(iii) A control system 111 that is responsive to a control signal thereby to meter a rate of flow through the second input 113.(iv) An output configured to release provide a combined gas output including a first component derived from the first emissions gas feed and a second component derived from the recycled combustible gas feed wherein the combined gas output has a controlled ratio of a combustible component and an inert component.

[0030] It will be appreciated that the gas combiner arrangement optionally includes a 3-way valve with associated control infrastructure.

[0031] Specifically, in the illustrated example, the recycled combustible gas feed is high a CH4 content gas feed. The control system meters this high CH4 content gas to mix with the emission gas feed, thereby to achieve a desired ratio of CH4:CO2 (referred to herein as the “controlled ratio) The controlled ratio is preferably based on a usage metric. For example, where the gas is to be provided to a gas engine, the controlled ratio should be at least 20%- 25% CH4. This may be achieved by using a high combustible component gas feed of about 20% or greater (for example 20% CH4 can be used to being an input CH4 content up to over 20% combined). Preferably a fuel rich gas is used for the recycled combustible gas feed, preferably over 30% CH4 and more preferably over 40% CH4. In one embodiment the recycled combustible gas feed has a CH4 content of about 44%

[0032] The manner by which the control system operates varies between embodiments. One or more of the following approaches may be used.• A methane sensor is provided upstream of fugitive emissions feed gas input 112 (e.g. sensor 104) thereby to monitor in real-time methane content in the emissions feed gas source. Based on that methane content, the control system defines control signals thereby to selectively meter gas flow through recycled combustible gas input 113 in real time thereby to achieve the desired controlled ratio at combined gas output. This optionally makes use of a further methane sensor upstream of the emissions feed gas input 112, thereby to monitor real time methane content in the gas processing plant feed gas.• The mission feed gas is batched via a chamber arrangement prior to release to the emissions feed gas input, and released in batched supplies. A methane sensor is in that chamber thereby to monitor in methane content in the emissions feed gas source on a per-batch basis. Based on that methane content, the control system defines control signals thereby to selectively meter gas flowthrough recycled combustible gas input 113for batched release thereby to achieve the desired controlled ratio at combined gas output on a per-batch basis. This optionally makes use of a further methane sensor upstream of the emissions feed gas input 112, thereby to monitor real time methane content in the emissions feed gas.• The gas combiner arrangement performs a batch-and-release process, whereby a chamber is first filled with a predefined quantity of gas via the emissions geed gas input 112, and then that is supplemented via the recycled combustible gas input 113 until a methane sensor in the chamber indicates that the controlled ratio has been satisfied.

[0033] In a preferred embodiment, a methane sensor is operated to measure (in real time) the methane content of the incoming fugitive emissions. Data from this sensor is processed to automatically relay to a valve controller instructions for releasing the fuel rich recycled methane, thereby to increase the methane content in the combined output. A preferred target is around 20%, as this should be inflammable if the balance of gases are carbon dioxide and nitrogen. Once this combined feed is passed through a gas compressor it moves into the flammable range (methane of about 25% plus). Ideally, it is advantageous for the methane proportion to be around 40% so there is complete combustion (particularly useful in terms of generating power for export).

[0034] It should be noted that in any of the above examples, the controlled ratio may in some instances be achieved via the emissions feed gas source in isolation, and that the gas combiner arrangement does not need to introduce supplementation of the recycled combustible gas. For example, where the controlled ratio is a minimum threshold of 20% CH4, supplementation is only required when there is <20% CH4 in the emissions feed gas.

[0035] In some further embodiments, where the controlled ratio requires a precise value, or a range with an upper CH4 content threshold, the gas combiner arrangement may be configured to enable metering of a further source of gas (e.g. CO2) thereby to decrease CH4 content in the combined gas output.

[0036] In the illustrated embodiment, the combined gas provided a combined gas output 114 is a feed having a CH4 content of either 20% or a feed having a CH4 content of at least 20%. In relation to the former, this may result where the emissions source facility is known to be low in CH4 content, requiring constant supplementation (being a key advantageous use case for the subject technology).

[0037] In the illustrated embodiment, the combined gas output 114 is coupled to a gas-gas separation system 120, which is configured and operated to separate CO2 from the mix of CO2 and CH4. Preferably, the controlled ratio (i.e. the proportion of CH4 provided via the combined case output 114) is defined based on operational parameters of gas-gas separation system 120, such that the CH4 content is optimised for the purposes of that system.

[0038] In the illustrated embodiment, the gas-gas separation system is configured to provide two output feeds: (i) a primary output 121 , which in this embodiment with high CH4 content (for example over 20-25%, and more preferably over 40%); and (ii) a secondary output 122, which in this embodiment is a high purity CO2 feed (e.g. >90%, or more preferably >93.5% purity, suitable for CO2 reuse). The primary output is used for purposes including the generation of recycled combustible gas (for supplementation of the emissions geed gas via gas combiner arrangement 110). The secondary output is made available for downstream utilisation 123, for example dry ice plant, used as a feed chemical for algae production, and other known and future commercial uses of carbon dioxide..

[0039] In the illustrated embodiment, primary output 121 is provided to a gas distribution arrangement 130, which includes:• An input 131 for receiving a feed of gas from primary output 121 .• An external supply output 132 which provides the high methane content gas for downstream utilisation 133 (for example use as a fuel, flaring, or other purposes such as chemical manufacturing utilisation in methane and / or such as steam methane reforming, methane pyrolysis, methanol manufacture, and others).• A recycled combustible gas output 134, which is coupled to recycled combustible gas input 113 of gas combiner arrangement 110 (optionally via one or more storage tanks and / or one or more bleed tanks, or other suitable arrangements).• A control system 135, which manages the operation of outputs 132 and 134. By way of example, this may be configured using a 3 way valve or the like, and be operated thereby to maintain a threshold range of high CH4 content gas in a store available for use by gas combiner arrangement 110.

[0040] In this manner, CH4 is recycled through the system as a whole, thereby to facilitate preservation of a desired level of methane content for delivery to the gas-gas separation system. The delivery of a specific gas composition to the gas-gas separation system ensures that the output of the gas-gas separation system is a product which has clearly defined gas composition and can be fed into a chemical manufacturing process, a high speed gas engine for pumping or power generation or equivalent.

[0041] FIG. 2A illustrates an example method according to one embodiment.

[0042] Block 201 represents a process including receiving an emissions gas feed (for example from a mine or the like), which includes a variable CH4 content. This variable content may at times be below 20%, or even below 10%, and as such unsuitable for flaring or use in other applications where continuous combustion is required.

[0043] Block 202 represents a process including measuring CH4 content in the emissions gas feed. This measurement is performed in real time, thereby to enable defining of control signals at block 204, which control metering of a recycled combustible has with high CH4 content (e.g. about 40% or greater). This metering is controlled thereby to provide a combined gas feed at block 205 which has a minimum threshold CH4 content (for example 20% or higher) at block 205.

[0044] Block 206 represents a process including providing the combined gas feed to a gasgas separation system, which is operated to separate one or more inert gases (e.g. CO2 and / or N2) from the combined gas feed. This results in an output of a recycled combustible gas at 207 (this having a higher CH4 content than the combined gas feed due to the separation) and an inert gas (e.g. high purity CO2) at block 208. The nature of the inert gas output depends on the type of gas-gas separation system used, and this may be selected based on desired used for the insert output.

[0045] The recycled combustive gas output at block 207 is made available for the combining process of block 205, and for other purposes (e.g. methane pyrolysis and the like).

[0046] By the method of FIG. 2A, an emissions gas feed is efficiently converted into a feed having a reliably high CH4 content.

[0047] FIG. 2B illustrates a variation on the method of FIG. 2A. In this case, a chamber (such as surge chamber) is used at block 211 to combine the emissions feed gas and the recycled combustible gas, and the combined gas is released only when measurements confirm that the minimum threshold CH4 content is reached (see block 212).

[0048] It will be appreciated that there are numerous possible variations on FIG. 2A and FIG. 2B which can be applied to combine the emissions gas feed and the recycled combustible gas feed to supplement variable (e.g. periodically and / or persistently low) CH4 content in the emissions gas feed, such that the combined output is suitable for combustion (e.g. via flaring and / or in engines or the like).Conclusions and Interpretation

[0049] It will be appreciated that the disclosure above provides useful improvements in the context of managing gases, for example fugitive emissions.

[0050] Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.

[0051] It should be appreciated that in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, FIG., or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of this invention.

[0052] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would beunderstood by those skilled in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0053] Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention.

[0054] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0055] Similarly, it is to be noticed that the term coupled, when used in the claims, should not be interpreted as being limited to direct connections only. The terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Thus, the scope of the expression a device A coupled to a device B should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including other devices or means. "Coupled" may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but yet still co-operate or interact with each other.Thus, while there has been described what are believed to be the preferred embodiments of the invention, those skilled in the art will recognize that other and further modifications may be made thereto without departing from the spirit of the invention, and it is intended to claim all such changes and modifications as falling within the scope of the invention. For example, any formulas given above are merely representative of procedures that may be used. Functionality may be added or deleted from the block diagrams and operations may be interchanged among functional blocks. Steps may be added or deleted to methods described within the scope of the present invention.

Claims

CLAIMS1 . A method for management of emissions, the method including: receiving an emissions gas feed from a source, the emissions gas feed including a variable ratio of a combustible component and an inert component; providing a control signal to a gas combiner arrangement, wherein the gas combiner arrangement includes:(i) a first input configured to receive the emissions gas feed;(ii) a second input configured to receive a recycled combustible gas feed;(iii) a controller that is responsive to the control signal thereby to meter a rate of flow through the second input; and(iv) an output configured to release provide a combined gas output including a first component derived from the first emissions gas feed and a second component derived from the recycled combustible gas feed wherein the combined gas output has a controlled ratio of a combustible component and an inert component; and providing the combined gas output to a downstream gas processing system; wherein the control signal is defined thereby to operate the controller such that the controlled ratio meets desired attributes.

2. A method according to claim 1 including: identifying a real-time value representative of the variable ratio; and based on the real-time value representative of the variable ratio defining the control signal.

3. A method according to claim 1 wherein the controlled ratio is defined by a threshold proportion of the combustible component.

4. A method according to any preceding claim including identifying a real-time value representative of a ratio of a combustible component to a non-combustible component in a chamber that is supplied by the emissions feed gas, and using real-time value as an input for defining the control signal.

5. A method according to any preceding claim wherein the downstream gas processing system is configured to process the combined gas output thereby to provide a source for the recycled combustible gas feed.

6. A method according to any preceding claim wherein the downstream gas processing system is configured to process the combined gas output thereby to provide a source of exportable combustible fuel.

7. A method according to any preceding claim wherein the downstream gas processing system includes a gas-gas separation system which is configured to separate the combined gas output into a two or more separation output components.

8. A method according to claim 7 wherein the two or more separation output components include a high-purity inert component.

9. A method according to claim 7 or claim 8 wherein the two or more separation output components include a component having a threshold proportion of combustible gas.

10. A method according to claim 9 wherein the component having a threshold proportion of combustible gas provides a source for the recycled combustible gas feed.

11. A method according to any preceding claim wherein the controlled ratio is selected thereby based on operational parameters of the gas-gas separation system.

12. A method according to any preceding claim wherein the control signal is defined responsive to the real-time value representative of the variable ratio thereby to cause the controlled ratio to remain substantially consistent.

13. A method according to any preceding claim wherein the downstream gas processing system includes a flare component.

14. A method according to any preceding claim wherein the combustible components include methane and the inert components include CO2.

15. A method according to any preceding claim wherein the combustible components are methane and the inert components are CO2.

16. A method according to any preceding claim wherein the second input is additionally configured to receive a supplementary combustible gas feed.

17. A method according to claim 17 wherein the supplementary combustible gas feed includes a source of methane or biomethane18. A method according to claim 17 or claim 18 including performing analysis thereby to determine a ratio of the recycled gas feed and the supplementary combustible gas feed.

19. A system configured to perform a method according to any preceding claim.

20. A system configured for management of emissions, the system including: a feed gas input configured to receive an emissions gas feed from a source, the emissions gas feed including a variable ratio of a combustible component and an inert component; a gas combiner arrangement, wherein the gas combiner arrangement includes:(i) a first input configured to receive the emissions gas feed;(ii) a second input configured to receive a recycled combustible gas feed;(iii) a controller that is responsive to the control signal thereby to meter a rate of flow through the second input; and(iv) an output configured to release provide a combined gas output including a first component derived from the first emissions gas feed and a second component derived from the recycled combustible gas feed, wherein the combined gas output has a controlled ratio of a combustible component and an inert component; and a delivery mechanism for providing the combined gas output to a downstream gas processing system; wherein the controller is operated such that the controlled ratio meets desired attributes.

21. A system according to claim 20 including a sensor input configured to receive a realtime value representative of the variable ratio, wherein the controller is controlled via a control signal that is defined in response to processing of the real-time value representative of the variable ratio.

22. A system according to claim 21 wherein the controlled ratio is defined by a threshold proportion of the combustible component.

23. A system according to claim 21 or claim 22 including identifying a real-time value representative of a ratio of a combustible component to a non-combustible component in a chamber that is supplied by the emissions feed gas, and using real-time value as an input for defining the control signal.

24. A system according to claim 20 or 22 wherein the downstream gas processing system is configured to process the combined gas output thereby to provide a source for the recycled combustible gas feed.

25. A system according to any one of claims 20 to 24 wherein the downstream gas processing system is configured to process the combined gas output thereby to provide a source of exportable combustible fuel.

26. A system according to any one of claims 20 to 25 wherein the downstream gas processing system includes a gas-gas separation system which is configured to separate the combined gas output into a two or more separation output components.

27. A system according to claim 26 wherein the two or more separation output components include a high-purity inert component.

28. A system according to claim 26 or claim 25 wherein the two or more separation output components include a component having a threshold proportion of combustible gas.

29. A system according to claim 28 wherein the component having a threshold proportion of combustible gas provides a source for the recycled combustible gas feed.

30. A system according to any one of claims 20 to 29wherein the controlled ratio is selected thereby based on operational parameters of the gas-gas separation system.31 . A system according to any one of claims 20 to 29 wherein the control signal is defined responsive to the real-time value representative of the variable ratio thereby to cause the controlled ratio to remain substantially consistent.

32. A system according to any one of claims 20 to 31 wherein the downstream gas processing system includes a flare component.

33. A system according to any one of claims 20 to 32 wherein the combustible components include methane and the inert components include CO2.

34. A system according to any one of claims 20 to 33 wherein the combustible components are methane and the inert components are CO2.

35. A system according to any one of claims 20 to 34 wherein the second input is additionally configured to receive a supplementary combustible gas feed.

36. A system according to claim 35 wherein the supplementary combustible gas feed includes a source of methane or biomethane37. A system according to claim 35 or claim 36 including a component configured for performing analysis thereby to determine a ratio of the recycled gas feed and the supplementary combustible gas feed.

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