Combusting biogas and capturing carbon dioxide

Abstract

A method of capturing carbon dioxide (CO2) from a biogas stream includes: flowing the biogas stream to a reactor, the biogas stream including biogenic methane and biogenic CO2; combusting the biogenic methane of the biogas stream in the reactor and generating a combustion CO2; flowing an exhaust gas stream from the reactor, the exhaust gas stream including the combustion CO2 and the biogenic CO2; and processing the biogenic CO2 and the combustion CO2 of the exhaust gas stream to form a product CO2 stream.

Description

COMBUSTING BIOGAS AND CAPTURING CARBON DIOXIDETECHNICAL FIELD

[0001] This disclosure relates to systems, apparatus, and methods for combusting biogas and capturing carbon dioxide.BACKGROUND

[0002] Capturing carbon dioxide (CO2) from the atmosphere is one approach to mitigating greenhouse gas emissions and slowing climate change. However, many technologies designed for CO2 capture from point sources, such as flue gas of industrial facilities, are generally ineffective in capturing CO2 from the atmosphere due to the significantly lower CO2 concentrations and large volumes of air required to process CO2 from the atmosphere. In recent years, progress has been made in finding technologies better suited to capture CO2 directly from the atmosphere. Some of these direct air capture (DAC) systems use a solid sorbent where an active agent is attached to a substrate. These DAC systems typically employ a cyclic adsorption-desorption process where, after the solid sorbent is saturated with CO2, it releases the CO2 using a humidity or thermal swing and is regenerated.

[0003] Other DAC systems use a liquid sorbent (sometimes referred to as a solvent) to capture CO2 from the atmosphere. An example of such a gas-liquid contact system would be one where a fan is used to draw air across a high surface area packing that is wetted with a solution comprising the liquid sorbent. CO2 in the air reacts with the liquid sorbent. The rich solution is further processed downstream to regenerate a lean solution and to release a concentrated CO2 stream.

[0004] During processing downstream, liquid and solid sorbent systems may need to liberate CO2 from a carbonate material formed when the CO2 is reacted with the sorbent material. For carbonates in solid form, this may be achieved with a heated reactor, sometimes referred to as a calciner, which heats the carbonate material to liberate CO2 for storage or further processing. Some of these reactors combust fossil fuels to generate the thermal energy required for reacting the carbonate material, which can increase the carbon intensity of the overall process.SUMMARY

[0005] In an example implementation, a method of capturing carbon dioxide (CO2) from a biogas stream includes: flowing the biogas stream to a reactor, the biogas streamincluding biogenic methane and biogenic CO2; combusting the biogenic methane of the biogas stream in the reactor and generating a combustion CO2; flowing an exhaust gas stream from the reactor, the exhaust gas stream including the combustion CO2 and the biogenic CO2; and processing the biogenic CO2 and the combustion CO2 of the exhaust gas stream to form a product CO2 stream.

[0006] In an aspect combinable with the example implementation, flowing the biogas stream to the reactor includes flowing the biogas stream to a calciner; and combusting the biogenic methane of the biogas stream in the reactor includes combusting the biogenic methane in the calciner.

[0007] Another aspect combinable with one, some, or all of the previous aspects further includes calcining a solid carbonate material in the calciner.

[0008] In another aspect combinable with one, some, or all of the previous aspects, calcining the solid carbonate material includes generating a calcined CO2; and processing the biogenic CO2 and the combustion CO2 includes processing the combustion CO2, the biogenic CO2, and the calcined CO2 to form the product CO2 stream.

[0009] In another aspect combinable with one, some, or all of the previous aspects, flowing the biogas stream to the calciner includes flowing the biogas stream with impurities including hydrogen sulfide (H2S); and calcining the solid carbonate material includes: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product, reacting some of at least one of the CaCCb and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product, and separating at least a portion of the at least one of the solid sulphite product and the solid sulphate product from the CaO product

[0010] In another aspect combinable with one, some, or all of the previous aspects, flowing the biogas stream to the calciner includes flowing the biogas stream with impurities; and calcining the solid carbonate material includes: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities.

[0011] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2 and the biogenic CO2 includes sequestering the product CO2 stream in a reservoir.

[0012] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2 and the biogenic CO2 includes mineralizing the product CO2 stream to form a solid material.

[0013] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2 and the biogenic CO2 includes providing the product CO2 stream as a feedstock for forming a chemical product.

[0014] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2 and the biogenic CO2 includes: cooling the exhaust gas stream to form a cooled exhaust gas stream; purifying the cooled exhaust gas stream to form a purified CO2 stream; and compressing the purified CO2 stream to form the product CO2 stream.

[0015] In another aspect combinable with one, some, or all of the previous aspects, combusting the biogenic methane of the biogas stream in the reactor includes oxy-firing the biogenic methane.

[0016] In another example implementation, a reaction system includes a piping network including a biogas pipeline configured to flow a biogas stream including 45%-75% of biogenic methane and 25%-55% of biogenic carbon dioxide (CO2); and a reactor configured to combust the biogenic methane of the biogas stream and generate heat and a combustion CO2. The reactor includes: an interior; at least one inlet in fluid communication with the interior, the at least one inlet including a biogas inlet in fluid communication with the biogas pipeline and configured to provide the biogas stream to the interior; and at least one outlet in fluid communication with the interior, the at least one outlet including an exhaust gas outlet configured to convey an exhaust gas stream from the interior, the exhaust gas stream including the combustion CO2 and the biogenic CO2.

[0017] In an aspect combinable with the example implementation, the at least one inlet includes a solids inlet configured to provide a solid carbonate material to the interior; the reactor is configured to calcine the solid carbonate material and generate a calcined CO2 and a solid oxide material; the exhaust gas outlet is configured to convey the calcined CO2 from the interior; and the at least one outlet includes a solids outlet configured to convey the solid oxide material from the interior.

[0018] In another aspect combinable with one, some, or all of the previous aspects, the solids inlet is configured to provide the solid carbonate material to the interior to form a bed of the solid carbonate material; and the biogas inlet is configured to provide the biogas stream to fluidize the bed of the solid carbonate material.

[0019] In another aspect combinable with one, some, or all of the previous aspects, the at least one inlet includes an oxygen inlet configured to provide an oxygen stream to the reactor.

[0020] In another example implementation, a method of capturing carbon dioxide (CO2) from atmospheric air, the method including: capturing the CO2 from the atmosphericair and generating a solid carbonate material; flowing a biogas stream to a calciner, the biogas stream including biogenic methane and biogenic CO2; flowing the solid carbonate material to the calciner; combusting the biogenic methane of the biogas stream in the calciner to generate heat and a combustion CO2, and calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream including the combustion CO2, the biogenic CO2 and the calcined CO2; and processing the combustion CO2, the biogenic CO2 and the calcined CChto form a product CO2 stream.

[0021] In an aspect combinable with the example implementation, flowing the biogas stream to the calciner includes flowing the biogas stream with impurities including hydrogen sulfide (H2S); and calcining the solid carbonate material includes: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and reacting some of at least one of the CaCCb and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product.

[0022] In another aspect combinable with one, some, or all of the previous aspects, flowing the biogas stream to the calciner includes flowing the biogas stream with impurities; and calcining the solid carbonate material includes: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities.

[0023] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the calciner includes adjusting a flow of the solid carbonate material to the calciner based on an amount of the biogenic CO2 in the biogas stream.

[0024] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the calciner includes increasing the flow of the solid carbonate material to the calciner when the amount of the biogenic CO2 in the biogas stream decreases.

[0025] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the calciner includes: filling at least one receptacle with the solid carbonate material upstream of the calciner when the amount of the biogenic CO2 in the biogas stream increases; and discharging the solid carbonate material from the at least one receptacle and to the calciner when the amount of the biogenic CO2 in the biogas stream decreases.

[0026] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the calciner includes flowing the solid carbonate material to the calciner at a solid carbonate material flow rate; and adjusting the flow of the solid carbonate material to the calciner includes adjusting the solid carbonate material flow rate based on the amount of the biogenic CO2 in the biogas stream.

[0027] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the calciner includes adjusting the capturing of the CO2 from the generating of the solid carbonate material.

[0028] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the calciner includes adjusting a flow of the solid carbonate material to the calciner based on an amount of the biogenic methane in the biogas stream.

[0029] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2, the biogenic CO2 and the calcined CO2 includes sequestering the product CO2 stream in a reservoir.

[0030] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2, the biogenic CO2 and the calcined CO2 includes mineralizing the product CO2 stream to form a solid material.

[0031] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2, the biogenic CO2 and the calcined CO2 includes providing the product CO2 stream as a feedstock for forming a chemical product.

[0032] In another aspect combinable with one, some, or all of the previous aspects, processing the combustion CO2, the biogenic CO2 and the calcined CO2 includes cooling the exhaust gas stream to form a cooled exhaust gas stream, purifying the cooled exhaust gas stream to form a purified CO2 stream, and compressing the purified CO2 stream to form the product CO2 stream.

[0033] In another aspect combinable with one, some, or all of the previous aspects, combusting the biogenic methane of the biogas stream in the calciner comprises oxy-firing the biogenic methane.

[0034] In another example implementation, a system for capturing carbon dioxide (CO2) from atmospheric air includes: at least one gas-liquid contactor operable to absorb at least a portion of the CO2 from the atmospheric air into a capture solution; at least one carbonate-forming reactor in fluid communication with the at least one gas-liquid contactor, the at least one carbonate-forming reactor operable to react the capture solution with calciumhydroxide to form solid calcium carbonate (CaCOs); a calciner in communication with the at least one carbonate-forming reactor. The calciner includes: an interior; at least one inlet in fluid communication with the interior, the at least one inlet including a biogas inlet configured to provide a biogas stream to the interior and a solids inlet configured to provide the solid CaCCh from the at least one carbonate-forming reactor; and at least one outlet in fluid communication with the interior, the at least one outlet including an exhaust gas outlet. The calciner is configured to: combust biogenic methane representing 45%-75% of the biogas stream and generate heat and a combustion CO2, and calcine the solid CaCOs and generating a calcined CO2 and a solid oxide material; and flow an exhaust gas stream from the interior through the exhaust gas outlet, the exhaust gas stream including the combustion CO2, the calcined CO2 and biogenic CO2 representing 25%-55% of the biogas stream.

[0035] An aspect combinable with the example implementation includes at least one receptacle upstream of the calciner and configured to receive the solid CaCCh from the at least one carbonate-forming reactor, and configured to discharge the solid CaCOs to the calciner.

[0036] Another aspect combinable with one, some, or all of the previous aspects includes a cooling unit in fluid communication with the exhaust gas outlet and configured to reduce a water vapour content of the exhaust gas stream and form a cooled exhaust gas stream, a purification unit in fluid communication with the cooling unit and configured to purify the cooled exhaust gas stream and form a purified CO2 stream, and a compressor unit in fluid communication with the purification unit and configured to compress the purified CO2 stream and form a product CO2 stream.

[0037] In another aspect combinable with one, some, or all of the previous aspects, the at least one inlet includes an oxygen inlet configured to flow oxygen to the interior.

[0038] In another aspect combinable with one, some, or all of the previous aspects, the calciner includes one of: a rotary calciner, a circulating fluidized bed calciner, a gravity-fed calciner, and a flash calciner.

[0039] In another aspect combinable with one, some, or all of the previous aspects, the calciner includes a flash calciner.

[0040] In another example implementation, a system for capturing carbon dioxide (CO2) from atmospheric air includes: at least one air contactor operable to contact at least a portion of the CO2 from the atmospheric air with a sorbent to form a solid carbonate material; and a calciner in communication with the at least one air contactor. The calciner includes: an interior; at least one inlet in fluid communication with the interior, the at least one inlet including a biogas inlet configured to provide a biogas stream to the interior and a solids inletconfigured to provide the solid carbonate material from the at least one air contactor; and at least one outlet in fluid communication with the interior, the at least one outlet including an exhaust gas outlet. The calciner is configured to: combust biogenic methane representing 45 %- 75% of the biogas stream and generate heat and a combustion CO2, and calcine the solid carbonate material and generating a calcined CO2 and a solid oxide material; and flow an exhaust gas stream from the interior through the exhaust gas outlet, the exhaust gas stream including the combustion CO2, the calcined CO2 and biogenic CO2 representing 25%-55% of the biogas stream.

[0041] An aspect combinable with the example implementation includes at least one receptacle upstream of the calciner and configured to receive the solid CaCCh from the at least one carbonate-forming reactor, and configured to discharge the solid CaCOs to the calciner.

[0042] Another aspect combinable with one, some, or all of the previous aspects includes a cooling unit in fluid communication with the exhaust gas outlet and configured to reduce a water vapour content of the exhaust gas stream and form a cooled exhaust gas stream, a purification unit in fluid communication with the cooling unit and configured to purify the cooled exhaust gas stream and form a purified CO2 stream, and a compressor unit in fluid communication with the purification unit and configured to compress the purified CO2 stream and form a product CO2 stream.

[0043] In another aspect combinable with one, some, or all of the previous aspects, the at least one inlet comprises an oxygen inlet configured to flow oxygen to the interior.

[0044] In another aspect combinable with one, some, or all of the previous aspects, the calciner includes one of: a rotary calciner, a circulating fluidized bed calciner, a gravity-fed calciner, and a flash calciner.

[0045] In another aspect combinable with one, some, or all of the previous aspects, the calciner includes a flash calciner.

[0046] In another example implementation, a method of capturing carbon dioxide (CO2) from atmospheric air includes: capturing CO2 from the atmospheric air and generating a solid carbonate material using a capture subsystem of a Direct Air Capture (DAC) system, the solid carbonate material having a first CO2 removal value representative of a first amount of CO2 removed from the atmospheric air using the capture subsystem; flowing a biogas stream to a reactor, the biogas stream including biogenic methane and biogenic CO2, the biogenic CO2 of the biogas stream having a second CO2 removal value representative of a second amount of CO2 removed from the atmospheric air by a portion of a biomass processed into the biogas stream; flowing the solid carbonate material to the reactor; combusting the biogenic methaneof the biogas stream in the reactor to generate heat and a combustion CO2, the combustion CO2 having a third CO2 removal value representative of a third amount of CO2 removed from the atmospheric air by a remainder of the biomass processed into the biogas stream; calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the reactor, the exhaust gas stream including the combustion CO2, the biogenic CO2 and the calcined CO2; and processing the exhaust gas stream to form a product CO2 stream, the product CO2 stream having a final CO2 removal value, the final CO2 removal value including at least a portion of each of the first CO2 removal value, the second CO2 removal value, and the third CO2 removal value.

[0047] In an aspect combinable with the example implementation, flowing the biogas stream to the reactor includes flowing the biogas stream with impurities including hydrogen sulfide (H2S), and calcining the solid carbonate material includes calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product, and reacting some of at least one of the CaCCh and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product.

[0048] In another aspect combinable with one, some, or all of the previous aspects, flowing the biogas stream to the reactor includes flowing the biogas stream with impurities, and calcining the solid carbonate material includes calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product, and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product, and combusting a second portion of the impurities.

[0049] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the reactor includes adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic CO2 in the biogas stream.

[0050] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the reactor includes increasing the flow of the solid carbonate material to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

[0051] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the reactor includes filling at least one receptacle with the solid carbonate material upstream of the reactor when the amount of the biogenic CO2 in the biogas stream increases, and discharging the solid carbonate material from the at least one receptacle and to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

[0052] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the reactor includes flowing the solid carbonate material to the reactor at a solid carbonate material flow rate, and adjusting the flow of the solid carbonate material to the reactor comprises adjusting the solid carbonate material flow rate based on the amount of the biogenic CO2 in the biogas stream.

[0053] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the reactor includes adjusting the capturing the CO2 from the atmospheric air and the generating the solid carbonate material.

[0054] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the reactor includes adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic methane in the biogas stream.

[0055] In another aspect combinable with one, some, or all of the previous aspects, processing the exhaust gas stream includes sequestering the product CO2 stream in a reservoir.

[0056] In another aspect combinable with one, some, or all of the previous aspects, processing the exhaust gas stream includes mineralizing the product CO2 stream to form a solid material.

[0057] In another aspect combinable with one, some, or all of the previous aspects, processing the exhaust gas stream includes providing the product CO2 stream as a feedstock for forming a chemical product.

[0058] In another aspect combinable with one, some, or all of the previous aspects, processing the exhaust gas stream includes cooling the exhaust gas stream to form a cooled exhaust gas stream, purifying the cooled exhaust gas stream to form a purified CO2 stream, and compressing the purified CO2 stream to form the product CO2 stream.

[0059] In another aspect combinable with one, some, or all of the previous aspects, combusting the biogenic methane of the biogas stream in the reactor includes oxy-firing the biogenic methane.

[0060] Another aspect combinable with one, some, or all of the previous aspects includes adjusting the final CO2 removal value by at least one of: adjusting a flow of the solid carbonate material to the reactor; and adjusting the capturing the CO2 from the atmospheric air and the generating the solid carbonate material.

[0061] In another example implementation^ method of capturing carbon dioxide (CO2) from atmospheric air includes: flowing a biogas stream to a reactor, the biogas stream including biogenic methane and biogenic CO2, the biogenic CO2 having a first biogas carbon removalvalue representative of CO2 removed from the atmospheric air by a portion of a biomass processed into the biogas stream; flowing a solid carbonate material to the reactor, the solid carbonate material embedding CO2 removed from the atmospheric air, the solid carbonate material having a solids carbon removal value representative of CO2 removed from the atmosphere and embedded in the solid carbonate material; combusting the biogenic methane of the biogas stream in the reactor to generate heat and a combustion CO2, the combustion CO2 having a second biogas carbon removal value representative of CO2 removed from the atmospheric air by a remainder of the biomass processed into the biogas stream; calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; and flowing an exhaust gas stream from the reactor, the exhaust gas stream including the combustion CO2, the biogenic CO2 and the calcined CO2, the exhaust gas stream having a final carbon removal value representative of the CO2 present in the combustion CO2, the biogenic CO2 and the calcined CO2, the final carbon removal value being greater than each of the first biogas carbon removal value, the second biogas carbon removal value, and the solids carbon removal value on their own.

[0062] In an aspect combinable with the example implementation, flowing the biogas stream to the reactor includes flowing the biogas stream with impurities including hydrogen sulfide (H2S), and calcining the solid carbonate material includes calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product, and reacting some of at least one of the CaCCb and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product.

[0063] In another aspect combinable with one, some, or all of the previous aspects, flowing the biogas stream to the reactor includes flowing the biogas stream with impurities, and calcining the solid carbonate material includes calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities

[0064] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the reactor includes adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic CO2 in the biogas stream.

[0065] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the reactor includes increasing the flow of the solid carbonate material to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

[0066] In another aspect combinable with one, some, or all of the previous aspects, adjusting the flow of the solid carbonate material to the reactor includes filling at least one receptacle with the solid carbonate material upstream of the reactor when the amount of the biogenic CO2 in the biogas stream increases, and discharging the solid carbonate material from the at least one receptacle and to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

[0067] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the reactor includes flowing the solid carbonate material to the reactor at a solid carbonate material flow rate, and adjusting the flow of the solid carbonate material to the reactor includes adjusting the solid carbonate material flow rate based on the amount of the biogenic CO2 in the biogas stream.

[0068] In another aspect combinable with one, some, or all of the previous aspects, flowing the solid carbonate material to the reactor includes adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic methane in the biogas stream.

[0069] Another aspect combinable with one, some, or all of the previous aspects includes processing the exhaust gas stream by cooling the exhaust gas stream to form a cooled exhaust gas stream, purifying the cooled exhaust gas stream to form a purified CO2 stream, and compressing the purified CO2 stream to form a product CO2 stream.

[0070] In another aspect combinable with one, some, or all of the previous aspects, combusting the biogenic methane of the biogas stream in the reactor includes oxy-firing the biogenic methane.

[0071] In another example implementation, a method for reducing a carbon emissions intensity of a direct air capture (DAC) system includes: flowing a biogas stream to a calciner of the DAC system, the biogas stream including biogenic methane and biogenic CO2; flowing a solid carbonate material to the calciner; producing a product CO2 stream from the DAC system by: combusting the biogenic methane of the biogas stream in the calciner to generate heat and a combustion CO2; calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream including the combustion CO2, the biogenic CO2 and the calcined CO2; and processing the exhaust gas stream to form the product CO2 stream. The DAC system has a lower carbon emissions intensity compared to if the DAC system combusted fossil-fuel natural gas in the calciner.

[0072] In another example implementation, a method for generating emissions credits includes: generating a first emissions credit by combusting in a calciner biogenic methane of a biogas stream that also includes biogenic CO2, combustion of the biogenic methane in the calciner generating heat and a combustion CO2; and generating a second emissions credit by: calcining in the calciner a solid carbonate material embedding CO2 removed from atmospheric air, to form a calcined CO2 released from the solid carbonate material, and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream including the combustion CO2, the biogenic CO2 and the calcined CO2; processing the exhaust gas stream to form a product CO2 stream; and storing at least some of the product CO2 stream.

[0073] In an aspect combinable with the example implementation, generating the first emissions credit includes venting at least some of the combustion CO2 to atmosphere.

[0074] Another aspect combinable with one, some, or all of the previous aspects includes generating a third emissions credit by producing the biogas stream comprising the biogenic methane and the biogenic CO2.

[0075] In another aspect combinable with one, some, or all of the previous aspects, the third emissions credit is an avoidance emissions credit representative of an amount of avoided methane emissions to atmosphere.

[0076] In another aspect combinable with one, some, or all of the previous aspects, the second emissions credit is a removal emissions credit representative of removing CO2 of at least the calcined CO2 and the biogenic CO2 from atmosphere.

[0077] In another aspect combinable with one, some, or all of the previous aspects, storing the at least some of the product CO2 stream includes sequestering the product CO2 stream in a reservoir.

[0078] In another aspect combinable with one, some, or all of the previous aspects, generating the first emissions credit includes generating the first emissions credit at a direct air capture (DAC) system, and generating the second emissions credit includes generating the second emissions credit at the DAC system.

[0079] In another example implementation, a calciner includes an interior; at least one inlet in fluid communication with the interior, the at least one inlet including a biogas inlet configured to provide to the interior a biogas stream comprising 45%-75% of biogenic methane and 25%-55% of biogenic carbon dioxide (CO2), and a solids inlet configured to provide a solid carbonate material to the interior; at least one outlet in fluid communication with the interior, the at least one outlet comprising an exhaust gas outlet; and at least one burner configured to combust the biogenic methane and generate heat in the interior and a combustionC02. The solid carbonate material is configured to calcine in the interior and generate a calcined CO2 and a solid oxide material. An exhaust gas stream is configured to flow from the interior through the exhaust gas outlet, the exhaust gas stream comprising the combustion CO2, the calcined CO2 and the biogenic CO2.

[0080] In another example implementation, a method of capturing carbon dioxide (CO2) from atmospheric air includes capturing the CO2 from the atmospheric air and generating a solid carbonate material, flowing a biomethane stream to a calciner, flowing the solid carbonate material to the calciner, combusting the biomethane stream in the calciner to generate heat and a combustion CO2, and calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material, flowing an exhaust gas stream from the calciner, the exhaust gas stream comprising the combustion CO2, biogenic CO2 and the calcined CO2, and processing the combustion CO2, the biogenic CO2 and the calcined CChto form a product CO2 stream.

[0081] In another example implementation, a method of capturing carbon dioxide (CO2) from atmospheric air includes generating a biogas stream in a biogas production facility from a biomass feedstock, the biogas stream including biogenic methane and biogenic CO2, the biogas stream having a biogas atmospheric carbon value representative of the CO2 captured from the atmospheric air by the biomass feedstock; capturing the CO2 from the atmospheric air and generating a solid carbonate material using a capture subsystem of a direct air capture (DAC) system, the solid carbonate material having a capture atmospheric carbon value representative of the CO2 captured from the atmospheric air using the capture subsystem; flowing the biogas stream to a reactor; flowing the solid carbonate material to the reactor; combusting the biogenic methane of the biogas stream in the reactor to generate heat and a combustion CO2, and calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the reactor, the exhaust gas stream including the combustion CO2, the biogenic CO2 and the calcined CO2; purifying the exhaust gas stream to form a purified CO2 stream, the purified CO2 stream having a combined atmospheric carbon value representative of the CO2 present in the combustion CO2, the biogenic CO2 and the calcined CO2, the combined atmospheric carbon value being greater than each of the biogenic atmospheric carbon value and the capture atmospheric carbon value; and storing the carbon in the purified CO2 stream.

[0082] The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Otherfeatures, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0083] FIG. 1 is a schematic representation showing steps in the production and refinement of biogas.

[0084] FIG. 2 is a perspective view of an example implementation of a reactor of a reaction system of the present disclosure.

[0085] FIG. 3 is a perspective view of an example implementation of a calciner of the present disclosure.

[0086] FIG. 3A is a perspective view of an example implementation of a calciner of the present disclosure.

[0087] FIG. 3B is a perspective view of an example implementation of a calciner of the present disclosure.

[0088] FIG. 3C is a perspective view of an example implementation of a calciner of the present disclosure.

[0089] FIG. 4 is a schematic illustration of a direct air capture system having a calciner, such as the calciner of FIG. 3

[0090] FIG. 5 A is a perspective view of another example direct air capture system of the present disclosure.

[0091] FIG. 5B is a perspective view of another example direct air capture system of the present disclosure.

[0092] FIG. 5C is a perspective view of another example direct air capture system of the present disclosure.

[0093] FIG. 6 is a flow chart of an example method of capturing CO2 from atmospheric air.

[0094] FIG. 7 is a flow chart of an example method of capturing CO2 from atmospheric air.

[0095] FIG. 8 is a flow chart of an example method for reducing the carbon emissions intensity of a direct air capture system.

[0096] FIG. 9 is a flow chart of an example method for generating emissions credits.

[0097] FIG. 9A is an example illustration of embedded emissions and credits associated with the production of biogas and its use by a direct air capture system.

[0098] FIG. 10 is a flow chart of an example method of capturing CO2 from a biogas stream.

[0099] FIG. 11 is a flow chart of an example method of capturing carbon dioxide (CO2) from atmospheric air.

[0100] FIG. 12 is a flow chart of an example method of capturing carbon dioxide (CO2) from atmospheric air.

[0101] FIG. 13 is a schematic diagram of an example control system for a calcination system of the present disclosure.DETAILED DESCRIPTION

[0102] The present disclosure relates to the combustion of natural hydrocarbons, or hydrocarbons derived from non-fossil-fuel sources. In particular, and referring to FIG. 1, the present disclosure relates to the combustion of biogas 101 in a reactor 210 (see FIG. 2). The biogas 101 is a gaseous product, and is a mixture of methane (CH4), CO2 and small quantities of other gases produced by different decomposition processes, such as anaerobic digestion of organic matter in a biomass 102 feedstock. The biogas 101 may also contain particulates. The precise composition of the biogas 101 depends on the type of the biomass 102 and the production platform 104. The biomass 102 is typically solid matter, even when entrained in a liquid. Non-limiting examples of biomass 102 from which the biogas 101 can be generated include energy crops, agricultural crop residues, animal waste, forestry residues, algae, wood processing residues, wood pellets, municipal waste, wet waste (crop wastes, forest residues, purpose-grown grasses, woody energy crops, algae, industrial wastes, sorted municipal solid waste [MSW], urban wood waste, and food waste), and combinations of the preceding. Nonlimiting examples of production platforms 104 for generating the biogas 101 from the solid biomass 102 include biodigesters, landfill gas recovery systems, and wastewater treatment plants. This variation in the composition of the biogas 101 means that the energy content of the biogas 101 can vary. For example, the lower heating value (LHV) of the biogas 101 may be between 16 megajoules per cubic metre (MJ / m3) and 28 MJ / m3. Other energy content values are possible.

[0103] The gaseous methane content of the biogas 101 typically ranges from 45% to 75% by volume, with most of the remaining content (approximately 25% to 55%) being gaseous CO2. The gaseous methane content of the biogas 101 is referred to herein as “biogenic methane” because it is produced or brought about by living organisms, during the process of generating the biogas 101 from the biomass 102. For similar reasons, the gaseous CO2 contentof the biogas 101 is referred to herein as “biogenic CO2.” Both the biogenic methane and the biogenic CO2 embody or include CO2 that has been captured directly from the atmosphere via biological fixation of atmospheric CO2 during the photosynthesis process that formed the biomass 102.

[0104] In the present disclosure, and referring to FIG. 1, the biogas 101 is combusted directly in a reactor 210, and may be used to generate heat for purposes described herein.

[0105] As an alternative to combusting the biogas 101 directly in the reactor 210, the biogas 101 can be upgraded or refined to make biomethane 106, also known as “renewable natural gas.” Referring to FIG. 1, the biomethane 106 is distinct from the biogas 101 in that the biomethane 106 is a near-pure source of methane (above 90% methane by volume). In this regard, a volume of the biomethane 106 has approximately the same calorific value as the same volume of natural gas (e.g., fossil-fuel derived methane). The biomethane 106 is produced in a refinery 108 or upgrader, either by upgrading the biogas 101 to remove its CO2 content and other contaminants present in the biogas 101, or through the gasification of solid biomass followed by methanation. The biomethane 106 has a greater energy content than the biogas 101. For example, the biomethane 106 may have an LHV of around 36 MJ / m3. The refinery 108 may include gas scrubbers, water knock-out units, membranes, compressors and other capital-intensive equipment.

[0106] The biogenic CO2 of the raw biogas 101, along with other undesired gaseous or solid elements, is removed when the biogas 101 is refined in the refinery 108, as represented in FIG. 1 with removal stream 112. Furthermore, the removal stream 112 may contain losses of some of the biogenic methane that can occur during the refining process in the refinery 108. The gases of the removal stream 112 can be vented to the atmosphere. The elements making up the removal stream 112 may need to be removed from the biogas 101 so that the resulting biomethane 106 complies with required or desired product specifications, as not all reactors can handle or process some of the non-methane elements in the biomethane 106. Thus, the refining process of the biogas 101 can result in emissions of greenhouse gases. These emissions may increase the carbon intensity of the resulting biomethane 106. If it is desired to reduce the carbon intensity of the biomethane 106 produced in the refinery 108, the refinery 108 may include equipment to capture, purify and compress gases (e.g., the biogenic CO2 and the biogenic methane) of the removal stream 112, but this may add to the unit cost of the biogenic methane. This additional processing may also increase the difficulty in providing a negative emission renewable natural gas product.

[0107] In contrast, implementations of the present disclosure relate to combusting the biogas 101 in its “unrefined” or raw form, e.g., before the biogas 101 has been refined into the biomethane 106. By combusting the biogenic methane of the biogas 101 and capturing the products of combustion, the systems, apparatus, and methods disclosed herein help to avoid the atmospheric emissions associated with upgrading the biogas 101 to the biomethane 106, and also help to remove CO2 from the atmosphere. Furthermore, when the combustion of the biogas 101 is combined with DAC systems or components, as disclosed below, it becomes possible to capture more CO2 from the atmosphere than would be possible with the capture components of the DAC system alone.

[0108] Referring to FIG. 2, the reactor 210 is a component of a reaction system 200. The reaction system 200 is a collection of apparatuses, piping, mechanisms and objects which work together to react a flow of the biogas 101 (sometimes referred to herein as a “biogas stream 101 S”). The reactor 210 is a vessel or other body that is at least partially hollow, and which is capable of receiving the biogas stream 101 S and supporting the reaction. The reactor 210 may thus be referred to herein as a “reactor vessel 210.” The reactor 210 has an interior 212 which is some or all of the inner volume of the reactor 210 and which is delimited by the walls of the reactor 210. The interior 212 is the location of the reactor 210 in which the reaction takes place, and is thus configured for receiving the biogas stream 101 S. The interior 212 communicates with one or more inlets 214, and with one or more outlets 216 of the reactor 210. In some aspects, the term “communicates,” with respect to the present disclosure, means that solids, liquids, gases and / or combinations of any of these material phases are received in, and discharged from, the interior 212 of the reactor 210 via the inlets 214 and via the outlets 216. For example, and referring to FIG. 2, one of the inlets 214 is a biogas inlet 214F through which the biogas stream 101 S is received in the interior 212. Similarly, one of the outlets 216 is an exhaust gas outlet 216 from which an exhaust gas stream 208, which includes the products of combustion of the biogas stream 101 S, is discharged from the interior 212 of the reactor 210. The inlets 214 and the outlets 216 may be any ports, openings or other similar accesses in a wall of the reactor 210, or defined by one or more flanges of the reactor 210. Although sometimes described and shown in the present disclosure as separate from one another, one or more of the inlets 214 may be combined with each other, and / or with one or more of the outlets 216. Similarly, one or more of the outlets 216 may be combined with each other, and / or with one or more of the inlets 214. Each inlet 214 and each outlet 216 may themselves include multiple branches or ports to define a plural inlet 214 or a plural outlet 216.

[0109] The reaction system 200 includes a piping network 220. The piping network220 is a series of interconnected pipes, lines, and other similar conduits through which different materials are moved to, through and / or from the reaction system 200. The piping network 220 includes multiple pipelines through which materials are moved from one location to another. One of the pipelines of the piping network 220 is an exhaust gas pipeline 221 that is fluidly coupled to, and extends from, the exhaust gas outlet 216. Yet another pipeline of the piping network 220 is a biogas pipeline 227 that is coupled to, and extends from, the biogas inlet 214, and which helps to convey the biogas stream 101 S to the interior 212 of the reactor 210. In some embodiments, the biogas pipeline 227 is specifically configured to convey the pressurized biogas stream 101S. The biogas pipeline 227 may have properties, such as one or more of the material of construction (MOC), pressure rating, and diameter so that the biogas pipeline 227 can convey under pressure the biogas stream 101 S comprising 45%-75% of biogenic methane and 25%-55% of biogenic CO2, in addition to any other elements which may be present in the biogas stream 101 S in small amounts. Each of the pipelines of the piping network 220 may include, or be formed of, one or more pipes or one or more pipe segments, and include any other devices (e.g., valves, flanges, ports, etc.) needed for the pipelines to move the material associated with the pipeline in the present disclosure.

[0110] In operation, the reactor 210 combusts the biogenic methane of the biogas stream 101S. The reactor 210 combusts the biogenic methane in the presence of oxygen. The oxygen may be provided to the interior 212 of the reactor 210 via the biogas inlet 214F, or via its own dedicated inlet 214. The reactor 210 combusts the biogenic methane with oxygen to generate heat, and gaseous products of combustion including water vapour, oxygen, etc., as well as a combustion CO2 stream 205. The gaseous products of combustion flow from the interior 212 via the exhaust gas outlet 216 as an exhaust gas stream 208. The exhaust gas stream 208 is depicted in FIG. 2 with its constituent gases, including water vapour, residual / unreacted oxygen, etc. shown as combustion product stream 209, as well as the combustion CO2 stream 205. The reactor 210 may be equipped with any suitable devices to combust the biogenic methane. For example, and referring to FIG. 2, the reactor 210 includes one or more burners 218 at one end of the reactor 210. The burners 218 distribute the biogas stream 101 S, including both its biogenic methane and biogenic CO2 components, and provide ignition. The burners 218 may only be used during a start-up period of the reactor 210, after which the heat generated in the reactor 210 sustains the combustion reaction. Thus, the reactor 210 provides the necessary heat to enable auto-ignition of the biogenic methane after an initial period during which the interior 212 is heated by combusting the biogenic methane with the burners 218. In an alternate implementation, the reactor 210 is free of burners 218, and the heat needed tosustain combustion within the reactor 210 is generated upstream of the reactor 210 and flowed into the reactor 210 to sustain continued combustion of the biogenic methane within the reactor 210.

[0111] The biogenic methane is combusted in the reactor 210, while the biogenic CO2 of the biogas stream 101 S passes through as an inert, such that the exhaust gas stream 208 flowing from the interior 212 includes the CO2 of both a biogenic CO2 stream 211 and the combustion CO2 stream 205. The biogenic CO2 stream 211, the combustion CO2 stream 205 and the combustion product stream 209 are shown as separate streams in FIG. 2 for the sole purpose of explaining the reaction products of the biogenic methane, it being understood that the products of the streams are comingled and constitute the single exhaust gas stream 208. Thus, the products from combustion of the biogenic methane (the combustion CO2 stream 205 and the combustion product stream 209) as well as the biogenic CO2 stream 211 are conveyed from the reactor 210 as part of the exhaust gas stream 208. In implementations where the biogas stream 101S is composed of 45% to 75% by volume of biogenic methane and approximately 25% to 55% of biogenic CO2, the biogenic CO2 represents a first percent volume of the exhaust gas stream 208 and the combustion CO2 represents a second percent volume of the exhaust gas stream 208. By converting the biogenic methane of the biogas stream 101 S into the CO2 of the combustion CO2 stream 205 through the combustion reaction, the reactor 210 is able to reduce the global warming potential of the biogenic methane compared to if the biogenic methane was vented to atmosphere, since the biogenic methane is a more potent greenhouse gas than the CO2 of the combustion CO2 stream 205. Thus, the combustion alone of the biogenic methane in the reactor 210 is enough to reduce the greenhouse gas potential of the biogenic methane.

[0112] If it is desired to further lower the global warming potential of the exhaust gas stream 208, the reaction system 200, the reactor 210 and / or a downstream facility or device can process the CO2 present in the exhaust gas stream 208. In example implementations, the term “process” or “processing” as used herein refers to treatment of the CO2 present in the exhaust gas stream 208, such that the CO2 can be stored or fixed, either permanently or over a time period that is relevant to mitigating the greenhouse gas effect or reducing the effects of climate change, such that the CO2 is prevented from returning to the atmosphere over that time period.

[0113] One example processing technique involves cooling, purifying and pressurizing the CO2 of the biogenic CO2 stream 211 and of the combustion CO2 stream 205, such as shown in FIG. 2. The exhaust gas stream 208 may be cooled to form a cooled exhaust gas stream 208C. Referring to FIG. 2, the exhaust gas stream 208 may be flowed through a cooling unit230, which may include a chiller, a heat exchanger, a condenser, a spray tower, a scrubber or a combination of these components, such that the water vapour content of the exhaust gas stream 208 is reduced or removed. The cooled exhaust gas stream 208C flowing from the cooling unit 230 may have no water content, or less water content than the exhaust gas stream 208 flowing into the cooling unit 230. The cooled exhaust gas stream 208C flowing from the cooling unit 230 has a higher concentration of CO2 than the exhaust gas stream 208 flowing into the cooling unit 230. The cooled exhaust gas stream 208C may then be purified to remove elements from the cooled exhaust gas stream 208C and form a purified CO2 stream 208P. Referring to FIG. 2, the cooled exhaust gas stream 208C may be flowed through a purification unit 232, which may include a baghouse, cyclone, an electrostatic precipitator, molecular sieve dryer, cryogenic purification tower, glycol, catalytic oxidation, or a combination of these components, such that any remaining water and elements (e.g., solids like dust or non-process elements, or gases like oxygen and nitrogen) can be removed from the cooled exhaust gas stream 208C, in order to form the purified CO2 stream 208P. The purified CO2 stream 208P may have a high concentration of CO2, for example greater than or equal to 95% volume. The purified CO2 stream 208P may then flow from the purification unit 232 to a compressor unit 234, where the purified CO2 stream is compressed to form a product CO2 stream 208F. The product CO2 stream 208F may be flowed for additional downstream processing, examples of which are described below.

[0114] The additional processing of the CO2 may result in the CO2 being captured. In example implementations, the term “capture” or “capturing” as used herein refers to storing or fixing of the CO2, either permanently or over a time period that is relevant to mitigating the greenhouse gas effect or reducing the effects of climate change, such that the CO2 is prevented from returning to the atmosphere over that time period.

[0115] One example of additional processing of the CO2 that results in its capture is sequestering the CO2. Referring to FIG. 2, the CO2 of the product CO2 stream 208F, which includes the CO2 of the biogenic CO2 stream 211 and of the combustion CO2 stream 205, can be delivered downhole and sequestered in a geological formation, subsurface reservoir, carbon sink, and the like (designated collectively as “reservoir 236”). The product CO2 stream 208F may be at a sufficiently high pressure to be injected into the reservoir 236, or may require additional compression, such as in the compressor unit 234, prior to being injected into the reservoir 236. The CO2 sequestered in the reservoir 236 is captured CO2. This capture may take different forms. For example, the CO2 may be injected in the reservoir 236 so as to mineralise with elements of the geology of the reservoir 236. In another example, the CO2 may be injectedin the reservoir 236 for enhanced oil recovery by injection into one or more wellbores to enhance production of hydrocarbons from the reservoir 236 so as to extract materials from the reservoir 236, such as hydrocarbons (a process known as enhanced oil recovery or EOR), or brines. In another example, the CO2 may be injected in the reservoir 236 for sequestering only, for example in a saline reservoir 236 or one where EOR is not occurring.

[0116] Another example of additional processing of the CO2 that results in its capture is mineralizing the CO2 into, or to form, a usable solid material 238. Referring to FIG. 2, the CO2 of the product CO2 stream 208F, which includes the CO2 of the biogenic CO2 stream 211 and of the combustion CO2 stream 205, is provided to a material mixture, such as the cement mixture used to form concrete, so that the CO2 becomes fixed in the concrete solid material 238. Other processes of mineralization of the CO2 to form the solid material 238 are possible, as are different solid materials 238.

[0117] Another example of additional processing of the CO2 that results in its capture is converting the carbon of the CO2 into a chemical product 240. Referring to FIG. 2, the CO2 of the product CO2 stream 208F, which includes the CO2 of the biogenic CO2 stream 211 and of the combustion CO2 stream 205, is provided as a feedstock to a process for producing the chemical product 240. Different chemical products 240 are possible. For example, the CO2 feedstock may be processed, along with other elements, to form polymers having different carbon chain lengths, such as various plastic chemical products 240. In another example, the CO2 feedstock may be processed to form alcohol chemical products 240, such as methanol, ethanol, ethylene. In another example, the CO2 feedstock may be processed, along with hydrogen, to form synthetic hydrocarbon chemical products 240, such as liquid or gaseous fuels or waxes. Regarding the conversion of the CO2 feedstock into the chemical product 240, it will be appreciated that the CO2 thus converted may be re-released to the atmosphere, for example, when the synthetic fuel is combusted. Regarding the conversion of the CO2 feedstock into a synthetic fuel, reference is made to US patent 11,655,421 and to PCT patent application number PCT / EP2022 / 082632, the entire contents of both of which are incorporated by reference herein.

[0118] The CO2 of the product CO2 stream 208F may be provided simultaneously as a feedstock to one or more of the reservoir 236, the solid material 238, and the chemical product 240, in any combination. Although the reservoir 236, the solid material 238 and the chemical product 240 are shown in FIG. 2 as receiving the product CO2 stream 208F, one or more of these capture products / techniques may receive CO2 that has been less processed. For example, the CO2 supplied to these capture products / techniques may bypass one or more of the coolingunit 230, the purification unit 232 and the compressor unit 234, such that the CO2 of the exhaust gas stream 208 (or of a stream that has been less processed than the product CO2 stream 208F) may be provided directly to these capture products / techniques, depending on the desired CO2 feedstock specifications for these capture products / techniques. The exhaust gas stream 208 may be provided to the cooling unit 230, the purification unit 232 and the compressor unit 234 in any order or sequence, and not necessarily in the sequence shown in FIG. 2. One or more of the cooling unit 230, the purification unit 232 and the compressor unit 234 may be features of the reaction system 200. In an alternate implementation, one or more of the cooling unit 230, the purification unit 232 and the compressor unit 234 are separate from the reaction system 200 and positioned downstream of the reaction system 200. The functions or features of one or more of the cooling unit 230, the purification unit 232 and the compressor unit 234 may be combined with each other. For example, the exhaust gas 208 may flow through one or more stages of "wet" CO2 compression before it is dehydrated, purified, and further compressed in a "dry" CO2 compression. In an implementation, the CO2 present in the exhaust gas stream 208 is processed in proximity to the reactor 210. In an alternate implementation, the CO2 present in the exhaust gas stream 208 is flowed for processing remotely of the reactor 210, such that processing the CO2 occurs offsite relative to the reactor 210.

[0119] It may thus be appreciated that, in implementations, the reactor 210 allows for capturing CO2 directly from the air, via the processing of biogas 101, and permanently storing this atmospheric CO2. In such implementations, the reactor 210 acts as a carbon capture, usage and storage (CCUS) unit, in that it captures atmospheric CO2 in the biogas. The reactor 210 may also be a component used to reduce the global warming potential of the biogas stream 101 S, by combusting the biogenic methane of the unrefined biogas stream 101 S and converting the biogenic methane to CO2 which has a lower global warming potential. By using the unrefined biogas stream 101 S, the reactor 210 allows for the biogenic methane to be used without having to upgrade the biogas stream 101 S to increase its biogenic methane content, such refinement itself likely to increase atmospheric emissions. Thus the reactor 210 allows for avoiding upgrading the unrefined biogas stream 101 S, so that it can instead be used as a feedstock containing embedded atmospheric carbon.

[0120] In other implementations, the reactor 210 functions to combust a refined or upgraded biogas stream 101 S having a higher methane content, such as a stream of the biomethane 106 described above. While the reactor 210 in such an alternate implementation may have a higher carbon intensity compared to implementations where the reactor 210 combusts only the biogas stream 101 S, biomethane 106 may be more readily available as a fuelsource, and / or easier to transport using existing infrastructure such as methane pipelines, such that the benefits of combusting biomethane 106 in the reactor 210 outweigh the benefits of combusting only the biogas stream 101 S in the reactor 210. In example implementations where biomethane 106 is combusted in the reactor 210, the biomethane 106 is the only source of methane combusted. In example implementations where biomethane 106 is combusted in the reactor 210, the biomethane 106 is mixed with the biogas stream 101 S in any desired blend such that both the biomethane 106 and the biogenic methane of the biogas stream 101 S are combusted.

[0121] The heat generated in the reactor 210 from combustion may be used to perform or facilitate other reactions that result in additional CO2 being captured. Referring to the FIG. 3, the reactor 210 includes, or is, a calciner 310. The description, features, reference numbers and advantages of the reactor 210 and of the reaction system 200 provided in relation to FIG. 2 apply mutatis mutandis to the calciner 310 and to the reaction system 300 of FIG. 3.

[0122] The calciner 310 is used for the calcination of solid carbonate materials 301. The solid carbonate material 301 is fed to the calciner 310 and undergoes a thermal treatment whereby the solid carbonate material 301 is raised to a high temperature without melting under restricted supply of oxygen, for the purpose of converting the solid carbonate material 301 into a solid oxide material 303 and a calcined carbon dioxide (CO2) stream 305. In one possible configuration, an example of which is provided in FIG. 3, the solid carbonate material 301 is, or includes, calcium carbonate (CaCCh). In such a configuration, the calcination reaction in the calciner 310 involves the decomposition of CaCO? at a calcination temperature of between 700-1050°C into solid calcium oxide (CaO) and CO2 gas, according to the following chemical reaction:

[0123] CaCO3(s) CaO(s) + CO2(g)

[0124] The calciner 310 can also calcine other solid carbonate materials 301. Nonlimiting examples of other solid carbonate materials 301 that can be calcined in the calciner 310 to yield the solid oxide material 303 and the calcined CO2 stream 305 include magnesium carbonate compounds, and carbonates containing one or more of sodium, potassium, uranium, aluminum, titanium, nickel, iron, copper, zinc, lead, manganese, strontium, cobalt, cadmium, bismuth, and barium.

[0125] In addition to having varied chemical compositions, the solid carbonate material 301 may be sourced from various industries and applications. The solid carbonate material 301 may be provided to the calciner 310 in different forms, such as pellets, pebbles, fines,ooids, and the like, and may consist of a range of sizes, from small particles as seen in applications that generate lime mud (e.g., between about 1 micron to about 100 microns diameter), to mid-range as seen in applications where carbonate pellets are formed through crystallization and / or precipitation (e.g., between about 50 microns to about 2 millimeters in diameter), up to larger ranges as seen in applications where the carbonate is either formed into pellets, bricks or other shapes, or is mined from geological sources (e.g., up to several centimeters in diameter).

[0126] Referring to FIG. 3, the reaction system 300 is a collection of apparatuses, piping, mechanisms and objects which work together to calcine the solid carbonate material 301. The calciner 310 is a vessel or other body that is at least partially hollow, and which is capable of receiving the solid carbonate material 301 and supporting the calcination reaction. The interior 312 is the location of the calciner 310 in which the calcination reactor takes place, and is thus configured for receiving the solid carbonate material 301. For example, and referring to FIG. 3, one of the inlets 314F, 3140, 314S (collectively referred to herein as inlets 314) of the calciner 310 is a solids inlet 314S through which the solid carbonate material 301 is received in the interior 312. Another one of the inlets 314 is a fluidization gas inlet 314F through which a fluidization gas stream 307 is received in the interior 312. Similarly, one of the outlets 316E, 316S (collectively referred to herein as outlets 316) of the calciner 310 is a solids outlet 316S through which the solid oxide material 303 is conveyed or discharged from the interior 312 after calcination. In some configurations, an example of which is provided in FIG. 3, the calciner 310 includes or is coupled to one or more solid-gas separators, such as one or more cyclones 313, which separate out particles of the solid oxide material 303 which might be entrained in the exhaust gas stream 308. In the calciner 310 of FIG. 3, the solid oxide material 303 separated in the cyclones 313 falls due to gravity in the down arm 315, where a portion of it can be reintroduced to the interior 312 of the calciner 310. In other possible implementations of the calciner 310, such as rotary type or gravity -type calciners 310, the solid oxide material 303 is discharged from the interior 312 using different techniques (see, for example, FIGS. 3 A and 3B).

[0127] One of the pipelines of the piping network 320 of the reaction system 300 is a solids feed pipeline 322 which conveys the solid carbonate material 301 to the solids inlet 314S. In example implementations the solids feed pipeline 322 is a conduit having a suitable orientation and size to flow solids. In other implementations, the solids feed pipeline 322 is another solids conveyance or transport device, such as a conveyor belt, a bucket elevator, a screw feeder, or a combination of these components. Y et another pipeline of the piping network320 is a solids discharge pipeline 327 that is coupled to, and extends from, the solids outlet 316S, and which helps to convey the calcined solid oxide material 303 from the interior 312 of the calciner 310. In the example of the calciner 310 of FIG. 3, the solids inlet 314S is located near the top of the body of the calciner 310. In other implementations, the solids inlet 314S is located along a side of the body of the calciner 310. Consequently, the solid carbonate material 301 supplied via the solids feed pipeline 322 to the solids inlet 314S falls due to gravity and collects toward the bottom of the body of the calciner 310, forming a bed 309 of the solid carbonate material 301. In an alternate configuration, the solids feed pipeline 322 includes, or feeds, a hopper at the solids inlet 314S. In an alternate implementation, the solids feed pipeline 322 includes, or is, a solids conveyance or transport device that mechanically transports the solid carbonate material 301 into the calciner 310. In such an implementation, the solids feed pipeline 322 may receive the solid carbonate material 301 from a conveyance or feed control unit 337, shown in FIG. 3, which helps to control the amount and / or rate of solid carbonate material 301 fed to the calciner 310.

[0128] Yet another pipeline of the piping network 320 is a fluidization pipeline 324. The fluidization pipeline 324 flows the fluidization gas stream 307 to the fluidization gas inlet 314F so that the fluidization gas stream 307 can fluidize the bed 309 of the solid carbonate material 301 in the calciner 310. Thus, in at least the implementation of FIG. 3, the calciner 310 flows gas (e.g., the fluidization gas stream 307) through a solid granular material (e.g., the bed 309 of the solid carbonate material 301) at flow rates that are high enough to suspend the solid carbonate material 301 in the interior 312 and cause the solid carbonate material 301 to behave as though it were a fluid. Thus, in at least the implementation of FIG. 3, the calciner 310 is a fluidized bed calciner 310. In some configurations of the calciner 310, an example of which is provided in FIG. 3, the fluidized bed calciner 310 includes componentry such as a distributor plate 318. The fluidization gas stream 307 enters the fluidized bed calciner 310 via the fluidization gas inlet 314F near the bottom portion of the body of the calciner 310, flows through the distributor plate 318 and flows up through the bed 309 of the solid carbonate material 301, where it fluidizes and mixes with both the solid carbonate material 301 and the solid oxide material 303.

[0129] In example implementations, such as in FIG. 3, the fluidization gas stream 307 is or includes the biogas stream 101 S. In example implementations, the fluidization gas stream 307 includes oxygen alone, and is provided via an oxygen inlet 3140 of the calciner 310. In example implementations, the fluidization gas stream 307 includes a mixture of the biogas stream 101 S and an oxygen stream. In example implementations, the fluidization gas stream307 is composed entirely of the biogas stream 101S. In implementations where the fluidization gas stream 307 is composed entirely of the biogas stream 101 S, the fluidization gas inlet 314F is the biogas inlet 214F. The fluidization gas stream 307 in such implementations includes the biogenic methane and the biogenic CO2. The biogas stream 101 S fluidizes the bed 309 of the solid carbonate material 301. Combustion of the biogenic methane in the calciner 310, either before or after fluidizing the bed 309, generates the combustion CO2 stream 205 described above, as well as heat. The heat causes calcination of the solid carbonate material 301, thereby generating the calcined CO2 stream 305. In implementations where the fluidization gas stream 307 includes the biogas stream 101 S, the biogas stream 101 S allows for fluidizing the bed 309 of the solid carbonate material 301 while also providing the energy feedstock for calcination, i.e. the biogenic methane which, when combusted, allows for calcining the solid carbonate material 301.

[0130] In implementations, such as in FIG. 3, the biogas stream 101 S is combusted in the presence of oxygen. The interior 312 of the calciner 310 is fed oxygen, via an oxygen pipeline 323 in fluid communication with the oxygen inlet 3140 of the calciner 310. The oxygen may be sourced from a dedicated unit, such as an air separation unit (ASU), a vacuum pressure adsorption system (VPSA), membranes, or a water electrolyser unit. In an alternate implementation, the oxygen may be provided to the interior 312 via the fluidization gas inlet 314F. The oxygen may assist in fluidizing the bed 309 of the solid carbonate material 301. In example implementations, the oxygen stream provided to the oxygen inlet 3140 has a concentration of at least 90% O2 by volume, or at least 95% O2 by volume, or at least 99% O2 by volume. In such implementations, the calciner 310 may be referred to as an “oxy-fired” calciner 310, in which the following reactions occur.

[0131] Combustion of biogenic methane: CF Cg) + 202(g) ->2H2O(g) + CO2(g) AH = - 891 kJ / mol

[0132] Oxy-fired calcination: CaCOs(s) + heat ->CaO(s) + CO2(g) AH = +178 kJ / mol

[0133] The fluidization gas stream 307 may have other compositions. For example, the fluidization gas stream 307 may include atmospheric air. In such a configuration, the reaction system 300 may include a scrubber or air separation downstream of the calciner 310 to remove nitrogen-containing compounds from the exhaust gas stream 308 of the calciner 310. In another possible configuration, the fluidization gas stream 307 may include steam. In such a configuration, the reaction system 300 may include a condenser or knock-out unitdownstream of the calciner 310 to remove water from the exhaust gas stream 308 of the calciner 310.

[0134] The calciner of FIG. 3 is a circulating fluidized bed (CFB) calciner 310. Other configurations of the calciner 310 are possible. For example, in another implementation and referring to FIG. 3 A, the calciner 310 is a rotary kiln or rotary calciner 310A. The rotary kiln calciner 310 rotates about an axis 305 A closer to the horizontal. A fuel inlet 324A allows the biogas stream 101 S to enter the interior 312A of the rotary kiln calciner 310A, a solids feed chute 322A conveys the solid carbonate material 301 into the interior 312A, a solids outlet 316SA allows the solid oxide material 303 to exit the interior 312A, and an exhaust gas outlet 316EA allows the exhaust gas stream 308 to flow from the interior 312A. In another possible implementation of the calciner 310 and referring to FIG. 3B, the calciner 310 is a gravity-fed calciner 310B. The solid carbonate material 301 falls due to gravity from the solids inlet 314SB near the top of the gravity-fed calciner 310B through an inner calciner chamber 312B. The biogenic methane of the biogas stream 101 S is combusted within the inner calciner chamber 312B to generate hot gases flowing in an upward direction within the inner calciner chamber 312B. The falling solid carbonate material 301 flows counter current to the hot gases and is calcined to generate the solid oxide material 303. The exhaust gas stream 308 exits the inner calciner chamber 312B via the exhaust gas outlet 316EB, and the solid oxide material 303 exits via the solids outlet 316SB.

[0135] In another possible implementation, and referring to FIG. 3C, the calciner 310 is a flash calciner 310C. The body of the flash calciner 310C may be formed of a single upright pipe or cylinder. The solid carbonate material 301 may be stored in a solids hopper 31 OH, and falls due to gravity onto a solids conveyor 310SC that feeds the solid carbonate material 301 to the interior 312C of the flash calciner 310C. The solids inlet 314SC is near the bottom of the flash calciner 310C. A fuel inlet 314AC allows the biogas stream 101 S to enter the interior 312C. The biogenic methane of the biogas stream 101 S is combusted to generate hot gases flowing in an upward direction from the bottom of the flash calciner 310C and through the interior 312C. The falling solid carbonate material 301 flows counter current to the hot gases and is calcined to generate the calcined products. The calcined products, which include the solid oxide material 303 and the exhaust gas stream 308, flow upwardly through the interior 312 and through the exhaust gas outlet 316EC to a solid-gas separator, such as cyclone 310CY. The exhaust gas stream 308, including the CO2 gaseous products resulting from calcination, is separated from the solid oxide material 303 in the cyclone 310CY. The separated exhaust gas stream 308 may be processed as disclosed herein.

[0136] The calciner 310 may be equipped with any suitable devices to combust the biogenic methane, such as the burners 218 of the reactor 210 of FIG. 2. The burners 218 may only be used during a start-up period of the calciner 310, after which the heat generated in the calciner 310 sustains the combustion reaction. Such start-up burners 218 may bring the bed 309 to a temperature which is higher than the auto-ignition temperature of the biogenic methane, such that the biogenic methane auto-ignites and generates the heat the reaction needs. In an alternate implementation, the calciner 310 is free of burners 218, and the heat needed to sustain combustion within the calciner 310 is generated upstream of the calciner 310 and flowed into the calciner 310 to sustain continued combustion of the biogenic methane within the calciner 310. The calciner 310 may also have structural features that allow for combusting the biogenic methane and using the biogas stream 101 S to fluidize the bed 309. Non-limiting examples of these structural features include inlets 314 sized and oriented to accommodate the required volume and flow rates of the biogas stream 101 S, and the holes of the distributor plate 318 being sized and / or oriented to accommodate the required volume and flow rates of the biogas stream 101 S.

[0137] In example implementations, the calciner 310 is operable or functions with impurities which may be present in the biogas stream 101S. Referring to Table 1 below, which shows the chemical composition in volume percent of different biogas streams 101 S depending on the source of their biomass 102, the biogas stream 101 S may contain trace amounts of compounds that are not the biogenic methane or the biogenic CO2. These compounds, sometimes referred to herein as “impurities”, are shown in grey in Table 1.Table 1: Composition of biogas (v / v%) per source of biomass

[0138] These impurities flow with the biogas stream 101 S into the calciner 310. The calciner 310 is able to function normally despite the presence of impurities in the biogas stream 101S, because of the reactions occurring in the calciner 310. For example, the hydrogen and ammonia present in the biogas stream 101S may be combusted along with the biogenic methane in the calciner 310, where combustion of the hydrogen and ammonia generates nitrogen (N2) and water. Similarly, the oxygen present in the biogas stream 101 S may react during combustion of the biogenic methane. Some of the impurities, such as the nitrogen, may not react within the calciner 310. Even if nitrogen compounds are formed in the calciner 310, such as nitrogen oxides (NOx), these will not negatively impact the operation of the calciner 310. Furthermore, any nitrogen or nitrogen-containing compounds present in the exhaust gas stream 308 flowing from the calciner 310 may be in such small quantities because 1) they are already present in such small quantities in the biogas stream 101 S, and 2) they would be further diluted by the comparatively much larger volumes of CO2 produced in the calciner 310 and present in the exhaust gas stream 308, such that the CO2 piping or CO2 product purity requirements may not be impacted by the trace presence of these impurities. The result would be the same for the other impurities which may not react in the calciner 310, such as siloxanes. Carbon monoxide may react in the calciner 310 to form CO2.

[0139] The nature of the reactions occurring within the calciner 310 help to process the hydrogen sulphide (H2S) impurity which may be present in the biogas stream 101 S. During calcination, the H2S reacts with oxygen in the calciner 310 to produce sulphur oxides (SOx), such as sulphur dioxide (SO2). The calcium solids present in the interior 312, such as calcium oxide (CaO) and / or calcium carbonate (CaCCh), can react with the gaseous sulphur dioxide to produce a solid sulphur compound, such as calcium sulfide (CaS), calcium sulphite (CaSCE) or calcium sulphate (CaSC ). Other solid sulphur compounds may be produced when H2S is reacted in the calciner 310. These solid sulphur compounds can be removed from the interior 312 either with the CaO or separately therefrom, in order to purge the calciner 310 of the solid sulphur compounds. If the solid sulphur compounds and the CaO are flowed from the interior 312 together, it is possible to separate the solid sulphur compounds from the CaO if it is desired to use the CaO.

[0140] In light of the preceding description of how the impurities react in the calciner 310, it will be appreciated that the calciner 310 disclosed herein and the calcination reactionmay help to remove or process impurities in the biogas stream 101 S so as to prevent these impurities contaminating the exhaust gas stream 308, or to reduce their impact on the purity of the exhaust gas stream 308. It follows that the biogas stream 101 S is particularly suitable to be combusted in the calciner 310 because many of the impurities in the biogas stream 101 S are not problematic to the operation of the calciner 310, can be consumed in the calciner 310, or are diluted so that they are not problematic to processing of the exhaust gas stream 308 downstream of the calciner 310. Referring specifically to the H2S impurity, the calciner 310 acts as a “sulphur scrubber” by reacting the H2S to form solid compounds which can then be removed from the interior 312. This may prevent sulphur oxides from contaminating the exhaust gas stream 308. This may also allow the H2S impurity to remain in the biogas stream 101 provided to the calciner 310, and thus eliminate the cost and complexity involved in treating the biogas stream 101 S to remove the H2S prior to combusting the biogas.

[0141] In example implementations and if desired to decrease the accumulation of nonprocess elements (NPEs) within the calciner 310, the biogas stream 101 S is scrubbed of one or more of the impurities prior to being combusted in the calciner 310. In example implementations separate from or combinable with the reaction of impurities in the calciner 310, the exhaust gas stream 308 is scrubbed or purified prior to processing its CO2 content so as to increase the purity of compounds (e.g., CO2) present in the exhaust gas stream 308. In alternate implementations to the reaction of impurities within the calciner 310, impurities are removed from the biogas stream 101 S before it is combusted in the calciner 310, and / or from the exhaust gas stream 308. In another implementation separate from or combinable with the reaction of impurities in the calciner 310, the calciner 310 may be shut down for periodic maintenance and for the removal of accumulated NPEs on surfaces of the calciner 310. Thus, in light of the preceding, it may be appreciated that impurities within the biogas stream 101 S combusted in the calciner 310 1) may not need to be removed from the biogas stream 101 S or exhaust gas stream 308 because they are present in such small concentrations, and / or 2) can be reacted within the calciner 310 to remove or reduce them from the exhaust gas stream 308.

[0142] The exhaust gas stream 308 is depicted in FIG. 3 with its constituent gases, including water vapour, oxygen, etc. shown as combustion product stream 319, as well as the combustion CO2 stream 317, the biogenic CO2 stream 311, and the calcined CO2 stream 305. These streams are shown as separate streams in FIG. 3 for the sole purpose of explaining the reaction products of the biogenic methane in the calciner 310, it being understood that the products of the streams are comingled and constitute the single exhaust gas stream 308. Thus, the products from combustion of the biogenic methane (the combustion CO2 stream 317 andthe combustion product stream 319), as well as the biogenic CO2 stream 311 and the calcined CO2 stream 305, are conveyed from the exhaust gas outlet 316E of the calciner 310 as part of the exhaust gas stream 308. The exhaust gas stream 308 flowing from the exhaust gas outlet 316E of the calciner 310 thus includes CO2 from three sources: the biogenic CO2 stream 211, the combustion CO2 stream 205 and the calcined CO2 stream 305.

[0143] The exhaust gas stream 308 may be processed using techniques like those disclosed above for the exhaust gas stream 208, in order to produce a stream like the product CO2 stream 208F. Therefore, the description, features, and advantages of processing the exhaust gas stream 208 provided in relation to FIG. 2 apply mutatis mutandis to the exhaust gas stream 308 of FIG. 3. In example implementations, processing the exhaust gas stream 308 includes processing the CO2 of: 1) the biogenic CO2 stream 311 of the biogas stream 101 S, 2) the combustion CO2 stream 317 produced from combustion of the biogenic methane, and 3) the calcined CO2 stream 305. It may thus be appreciated that, in example implementations, the calciner 310 allows for capturing CO2 directly from the air, via the processing of biogas 101, and permanently storing or capturing this atmospheric CO2, while also capturing additional CO2 embedded in the solid carbonate material 301. In such implementations, the calciner 310 acts as a carbon capture, usage and storage (CCUS) unit, in that it captures atmospheric CO2 in the biogas - including from combustion of the biogenic methane, and additional CO2 from the solid carbonate material 301.

[0144] The description, features, reference numbers and advantages of the calciner 310 provided in relation to FIG. 3 apply mutatis mutandis to the rotary kiln calciner 310A of FIG. 3A, to the gravity-fed calciner 310B of FIG. 3B and to the flash calciner 310C of FIG. 3C.

[0145] In other implementations, the calciner 310, 310A, 310B, 310C functions to combust a refined or upgraded biogas stream 101 S having a higher methane content, such as a stream of the biomethane 106 described above. While the calciner 310, 310A, 310B, 310C in such an alternate implementation may have a higher carbon intensity compared to implementations where the calciner 310, 310A, 310B, 310C combusts only the biogas stream 101 S, biomethane 106 may be more readily available as a fuel source, and / or easier to transport using existing infrastructure such as methane pipelines, such that the benefits of combusting biomethane 106 in the calciner 310, 310A, 310B, 310C outweigh the benefits of combusting only the biogas stream 101S in the calciner 310, 310A, 310B, 310C. In example implementations where biomethane 106 is combusted in the calciner 310, 310A, 310B, 310C, the biomethane 106 is the only source of methane combusted. In example implementations where biomethane 106 is combusted in the calciner 310, 310A, 310B, 310C, the biomethane106 is mixed with the biogas stream 101 S in any desired blend such that both the biomethane 106 and the biogenic methane of the biogas stream 101 S are combusted.

[0146] In implementations of the present disclosure, the solid carbonate material 301 embodies or includes CO2 captured directly from the atmosphere. In such implementations, an example of which is provided in FIG. 4, the calciner 310, 310A, 310B, 310C is part of a direct- air-capture (DAC) system 400 for capturing CO2 directly from atmospheric air.

[0147] In the implementation of FIG. 4, the calciner 310, 310A, 310B, 310C and / orthe reaction system 300 are part of the DAC system 400 for capturing CO2 directly from atmospheric air, according to one possible and non-limiting example of a use for the calciner 310, 310A, 310B, 310C. Concentrations of CO2 in the atmosphere are dilute, in that they are presently in the range of 400-420 parts per million (“ppm”) or approximately 0.04-0.042% v / v, and less than 1% v / v. These atmospheric concentrations of CO2 are at least one order of magnitude lower than the concentration of CO2 in point-source emissions, such as flue gases, where point-source emissions can have concentrations of CO2 ranging from 5-15% v / v depending on the source of emissions.

[0148] Referring to FIG. 4, one or more gas-liquid contactors 9200 absorb some of the CChfrom atmospheric air 1603 using a CO2 capture solution 9214 to form a CO2 rich solution 1602 and a stream of CCh-lean air 1609 (e.g., a stream of air in which the concentration of CO2 is less than that in the atmospheric air 1603). The CO2 rich solution 1602 flows from the gasliquid contactor 9200 to a carbonate-forming reactor, which in FIG. 4 is a pellet reactor 9110 of the DAC system 400. A slurry of calcium hydroxide 2104 is injected into the pellet reactor 9110. As Ca2+reacts with CO32' in the pellet reactor 9110, it promotes the dissolution and reaction of Ca(OH)2 with the CO3 ions via the causticization reaction, wherein calcium carbonate solids are formed, and KOH is replenished and returned to the gas-liquid contactor 9200 as the CO2 capture solution 9214 . Further processing of the calcium carbonate solids, including but not limited to filtering, washing, dewatering or drying, may occur prior to sending the calcium carbonate solids to downstream process units. A stream 9106 of calcium carbonate solids (e.g., the solid carbonate material 301) is flowed from the pellet reactor 9110 using any suitable solids conveyance technique to the calciner 310, 310A, 310B, 310C of the DAC system 400. The calciner 310, 310A, 310B, 310C calcines the calcium carbonate of the stream 9106 from the pellet reactor 9110 to produce a stream of gaseous CO22108 (e.g., the calcined CO2 stream 305) and a stream of calcium oxide (CaO) 2101 (e.g., the solid oxide material 303), with the heat produced from combusting the biogas stream 101 S in the calciner 310, 310A, 310B, 310C. Prior to being calcined, the stream 9106 of calcium carbonate solids may bepartially or fully dried, and thus may or may not have some moisture content when fed to the calciner 310, 310A, 310B, 310C. Some of the stream of gaseous CO2 2108 is processed for sequestration or other uses, thereby removing some of the CO2 from the atmospheric air 1603 processed in the gas-liquid contactor 9200, while a remainder of the stream of gaseous CO2 2108 may be recycled back to the calciner 310, 310A, 310B, 310C. The stream of gaseous CO2 2108 that is processed for sequestration or other uses may be processed as disclosed herein. In example implementations, some or all of the processing of the stream of gaseous CO2 2108 occurs within the battery limits of the DAC system 400. In alternate implementations, some or all of the processing of the stream of gaseous CO22108 occurs outside of the battery limits of the DAC system 400. The stream of calcium oxide (CaO) 2101 is slaked with water in a slaker 2130 of the DAC system 400 to produce the slurry of calcium hydroxide 2104 that is recycled back to the pellet reactor 9110. The DAC system 400 may include multiple gas-liquid contactors 9200, where each gas-liquid contactor 9200 forms a cell of a train / assembly of gasliquid contactors 9200. The DAC system 400 may include multiple pellet reactors 9110, and multiple slakers 2130.

[0149] The stream 9106 of calcium carbonate solids (e.g., the solid carbonate material 301) of the DAC system 400 that is calcined in the calciner 310, 310A, 310B, 310C may be produced according to other techniques for capturing CO2 from the atmospheric air 1603. For example, in an alternate implementation, the gas-liquid contactor 9200 of the DAC system 400 includes one or more air contactors which use a non-liquid sorbent to contact CO2 from the atmospheric air 1603 to directly form the stream 9106 of calcium carbonate solids (e.g., without the intermediary of the carbonate-forming reactor or of the slaker 2130). In such an implementation, the sorbent material may be a solid sorbent material such as calcium oxide or calcium hydroxide, which reacts with CChfrom the atmospheric air 1603 to form the stream 9106 of calcium carbonate solids. In another possible implementation, the gas-liquid contactor 9200 of the DAC system 400 uses a liquid sorbent, and the carbonate-forming reactor which receives the CO2 rich solution 1602 includes one or more reactors similar to those used in the Kraft pulping process to form calcium carbonate solids.

[0150] The exhaust gas stream 308 from the calciner 310, 310A, 310B, 310C includes its constituent gases the combustion product stream 319, the combustion CO2 stream 317, the biogenic CO2 stream 311, and the calcined CO2 stream 305. The exhaust gas stream 308 of FIG. 4 flowing from the exhaust gas outlet 316E of the calciner 310, 310A, 310B, 310C thus includes atmospheric CO2 from three sources: the biogenic CO2 stream 211, the combustion CO2 stream 205 and the calcined CO2 stream 305. It may thus be appreciated that, inimplementations such as shown in FIG. 4, the calciner 310, 310A, 31 OB, 3 IOC allows for capturing CO2 directly from the air, via combustion of the biogenic methane, capturing of the biogenic CO2 within the biogas stream 101 S, and via calcination of the solid carbonate material 301 produced by the DAC system 400, and permanently storing or capturing this atmospheric CO2. In such implementations, the calciner 310, 310A, 310B, 310C acts as a carbon capture, usage and storage (CCUS) unit, in that it captures atmospheric CO2 embedded in the biogas and in the solid carbonate material 301.

[0151] The combustion of the biogas stream 101 S in the calciner 310, 310A, 310B, 310C of the DAC system 400 may help to lower the carbon intensity of the DAC system 400 and of the DAC process, compared to a DAC process in which the calciner combusts natural gas derived from fossil fuels, assuming no significant carbon emissions associated with the production and transportation of the biogas stream 101 S. The lower carbon intensity of the CO2 produced by the DAC system 400 using biogas helps to lower the carbon intensity of products produced or derived from this CO2, thereby allowing these products to meet more stringent regulatory or compliance standards.

[0152] The combustion of the biogas stream 101 S in the calciner 310, 310A, 310B, 310C of the DAC system 400 also helps to lower the global warming potential of the biogas stream 101 S itself compared to if the biogas remained uncombusted, since the biogenic methane of the biogas stream 101 S is a more potent greenhouse gas than the CO2 it is converted to through combustion. The calciner 310, 310A, 310B, 310C of the DAC system 400 also provides a solution for processing the embedded CO2 of the biogas stream 101 S, which might otherwise be considered a “contaminant” that lowers the value of the biogas stream 101 S, or an “emission” in cases where the biogenic methane is combusted and the resulting biogenic CO2 and combustion CO2 is emitted to atmosphere. Combusting the biogas stream 101 S in the calciner 310, 310A, 310B, 310C of the DAC system 400 may therefore allow for providers or suppliers of the biogas stream 101 S to have a negative emission solution.

[0153] The combustion of the biogas stream 101 S in the calciner 310, 310A, 310B, 310C makes most of the thermal energy of the biogenic methane available for the calcination reaction, providing a combustion reaction with close to 100% thermal efficiency. When biogas is combusted in an engine, or to heat a working fluid to drive a turbine, the thermal efficiency may be less, in the range of 40%-60%.

[0154] The combustion of the biogas stream 101 S in its “unrefined” or raw form, e.g., before the biogas 101 has been refined into the biomethane 106, helps to avoid additional costs, emissions and energetic losses that can occur in the process of refining or purifying biogas.

[0155] The combustion of the biogas stream 101 S in the calciner 310, 310A, 310B, 3 IOC of the DAC system 400 allows for the DAC system 400 to capture CO2 from the atmosphere in addition to the atmospheric CO2 that can be captured with the gas-liquid contactors 9200, because the biogas stream 101 S combusted in the calciner 310, 310A, 310B, 310C is itself an additional source of CO2 captured from the atmosphere due to the biological fixation of CO2 during the photosynthesis that produces the biomass 102. The combustion of the biogas stream 101 S in the calciner 310, 310A, 310B, 310C of the DAC system 400 allows for the DAC system 400 to capture more CO2 from the atmosphere than would be possible in low carbon intensity configurations of the DAC process, such as where the calciner 310, 310A, 310B, 310C is electric or combusts hydrogen, because in such a configuration only the gasliquid contactors 9200 are capturing CO2 from the atmosphere. Thus, all CO2 produced in the DAC system 400 using the biogas stream 101 S comes from the atmosphere - either directly as embedded in the stream 9106 of calcium carbonate solids, or indirectly via the biogas stream 101 S. Furthermore, in addition to being another source of atmospheric CO2, the biogas stream 101 S serves as a source of calcination energy when combusted in the calciner 310, 310A, 310B, 310C.

[0156] The ability of the DAC system 400 using biogas to capture CO2 from the atmosphere in addition to the atmospheric CO2 captured with the gas-liquid contactors 9200 may be better appreciated with reference to FIGS. 5A-5C.

[0157] FIG. 5A shows an example DAC system 500A which, for the sole purposes of illustration, has a nameplate capacity of 1 Mt of CO2 removed from the atmosphere per year. The DAC system 500A includes a capture subsystem 542A and a calciner 510A. The capture subsystem 542A sends material to, and receives material from, the calciner 510A. In FIG. 5 A, the capture subsystem 542A flows the solid carbonate material 501 to the calciner 510A, and the calciner 510A returns the solid oxide material 503 to the capture subsystem 542A. The capture subsystem 542A may include any components or units intended to capture CO2 from the air and convert the captured CO2 to the solid carbonate material 501. For example, and referring to FIG. 5A, the capture subsystem 542A may include one or more gas-liquid contactors 9200 in fluid communication with one or more carbonate-forming reactors such as pellet reactors 9110, to produce the solid carbonate material 501 that is flowed to the calciner 510A. The capture subsystem 542A may also include one or more slakers 2130 to receive the solid oxide material 503 and produce the slurry of calcium hydroxide 2104. In another possible implementation of the capture subsystem 542A, the capture subsystem 542 may include one or more air contactors employing a solid sorbent to produce the solid carbonate material 501 thatis flowed to the calciner 51 OA. The calciner 51 OA of FIG. 5 A combusts natural gas 540 derived from fossil fuels, in the presence of oxygen 544. A product CO2 stream 508F flowing from the calciner 510A (after processing the exhaust gas from the calciner 51 OA, as described herein) is represented schematically as having a calcined CO2 stream 505 and a combustion CO2 stream 517. Only the calcined CO2 stream 505 represents CO2 captured from the atmosphere, since the CO2 of the combustion CO2 stream 517 is obtained from combusting the natural gas 540 derived from fossil fuels. The CO2 generated from combusting the natural gas 540 may be approximately 0.4 Mt / year of CO2, such that the DAC system 500A has a total production capacity of 1.4 Mt / year of CO2. This is the amount of CO2 which may be provided for sequestration or for use. These numbers are provided as examples only, given for the sole purpose of illustration.

[0158] Not all of the 1 Mt / year of CO2 removed from the atmosphere by the DAC system 500A can receive full carbon emissions credits, because of the use of the natural gas 540 derived from fossil fuels in the DAC system 500A. The carbon emission credits allocated to the DAC system 500A may be calculated on the net amount of CO2 removed from the atmosphere. Since the natural gas 540 has emissions associated with its production and transport (e.g., embedded emissions), these embedded emissions have to be considered when calculating the carbon emission credits for the DAC system 500A. The embedded emissions associated with the natural gas 540 may be equal to approximately 10% of the 1 Mt / year of CO2 removed from the atmosphere by the DAC system 500 A, such that the DAC system 500A may only get carbon emission credits for 90% of the CO2 it has physically removed from the atmosphere (these numbers are provided as examples only, given for the sole purpose of illustration). Thus, with the natural-gas fired calciner 510A of FIG. 5 A, not all of the nameplate CO2 removal capacity of the DAC system 500 A may be fully credited.

[0159] FIG. 5B shows another example DAC system 500B which, for the sole purposes of illustration, has the same total production capacity of 1.4 Mt / year of CO2 as the DAC system 500A. The DAC system 500B has similar components to the DAC system 500A of FIG. 5A, the primary difference being that the calciner 510B of the DAC system 500B combusts the biogas stream 101 S in the presence of the oxygen 544, instead of natural gas. The product CO2 stream 508BF flowing from the calciner 510B (after processing the exhaust gas from the calciner 510B, as described herein) is represented schematically as having three CO2 streams: the calcined CO2 stream 505, the combustion CO2 stream 517B, and the biogenic CO2 stream 511. All three CO2 streams represent CO2 captured from the atmosphere, including the CO2 ofthe combustion CO2 stream 517B because it is obtained from combusting the biogenic methane of the biogas stream 101S.

[0160] The CO2 generated from using the biogas stream 101 S in the DAC system 500B may be approximately 0.3 Mt / year of CO2 from combusting the biogenic methane, and 0.2 Mt / year of biogenic CO2. Since it is desired for the DAC system 500B to have the same total production capacity of 1.4 Mt / year of CO2 as the DAC system 500 A, this means that the CO2 removed from the atmosphere by the capture subsystem 542B is approximately 0.9 Mt / year of CO2. These numbers are provided as examples only, given for the sole purpose of illustration. Therefore, all the 1.4 Mt / year of CO2 produced by the DAC system 500B is captured atmospheric CO2. Assuming that the embedded emissions associated with producing and transporting the biogas stream 101 S may be equal to approximately 15% of the 1.4 Mt / year of CO2 removed from the atmosphere by the DAC system 500B, such that the DAC system 500B may only get carbon emission credits for 85% of the CO2 it has physically removed from the atmosphere (these numbers are provided as examples only, given for the sole purpose of illustration), the DAC system 500B still removes more CO2 from the atmosphere (e.g. 1.19 Mt / year) than the DAC system 500A (e.g. 0.9 Mt / year).

[0161] Since the DAC system 500B of FIG. 5B has the same total production capacity of 1.4 Mt / yr of CO2 as the DAC system 500A of FIG. 5A, the capture subsystem 542B of FIG. 5B needs to capture less atmospheric CO2 than that captured by the capture subsystem 542A of FIG. 5A, because the remaining atmospheric CO2 of the DAC system 500B is obtained from the biogas stream 101 S. This means that the capture subsystem 542B of FIG. 5B can operate at less capacity than the capture subsystem 542A of FIG. 5A. This lower capacity can be achieved using different techniques. For example, and referring to FIG. 5B, the capture subsystem 542B of FIG. 5B can have fewer units (e.g., fewer gas-liquid contactors 9200, fewer pellet reactors 9110, fewer slakers, etc.) than the capture subsystem 542A of FIG. 5A. In another example, the capture subsystem 542B of FIG. 5B can have smaller units (e.g., smaller gas-liquid contactors 9200, carbonate-forming reactors, slakers, etc.) than the capture subsystem 542A of FIG. 5 A. In yet another example, the capture subsystem 542B of FIG. 5B can operate more intermittently, or for reduced periods, compared to the capture subsystem 542A of FIG. 5A. Irrespective of how the lower capacity is achieved, there is likely a substantial savings in capital expenses and / or operating expenses between the capture subsystems 542A, 542B. Thus, with the biogas-gas fired calciner 510B of FIG. 5B, some of the total CO2 production capacity of the DAC system 500B includes CO2 captured from the atmosphere through photosynthesis.

[0162] Furthermore, and in contrast to the DAC system 500A, all or nearly all of the 1.4 Mt / year of CO2 removed from the atmosphere by the DAC system 500B can receive full carbon emissions credits, because of the use of the biogas stream 101 S in the DAC system 500B (assuming zero or negligeable embedded emissions for the biogas stream 101S). Since the biogas stream 101 S has fewer emissions associated with its production and transport than the natural gas 540 (and the biogas stream 101 S may even have negative emissions because it represents avoided methane emissions), the DAC system 500B is able to get carbon emission credits for all or nearly all of its total production capacity of 1.4 Mt / year of CO2 that it has physically removed from the atmosphere. This results in the DAC system 500B being able to generate approximately 55% more carbon emission credits than the DAC system 500, e.g., [(1.4-0 9 Mt / yr) / 0.9 Mt / yr],

[0163] The capture subsystem of a DAC system using a biogas-fired calciner can also be run at full capacity, in order to capture more atmospheric CO2 than would be possible if the calciner was fired by natural gas derived from fossil fuels. Such an implementation is illustrated in FIG. 5C, which shows another example DAC system 500C which has a higher total CO2 production capacity than the DAC systems 500A,500B of FIGS. 5A and 5B. The DAC system 500C has similar components to the DAC system 500B of FIG. 5B, including a calciner 510C that also combusts the biogas stream 101 S in the presence of the oxygen 544C. The primary difference between the DAC system 500C of FIG. 5C and the DAC system 500B of FIG. 5B is that the capture subsystem 542C of FIG. 5C is operated at a higher capacity than the capture subsystem 542B of FIG. 5B. The capture subsystem 542C of FIG. 5C is operated at the same capacity as the capture subsystem 542A of FIG. 5A. Since the higher capacity capture subsystem 542C may produce a greater quantity of the solid carbonate material 501, the calciner 510C may need additional thermal energy to calcine the additional solid carbonate material 501, compared to the calciner 510B of FIG. 5B. This additional thermal energy may be obtained by combusting a greater volume of biogas from the biogas stream 101 S, and / or by combusting biogas from the biogas stream 101 S that has a higher concentration of biogenic methane. In FIG. 5C, the product CO2 stream 508CF flowing from the calciner 510C (after processing the exhaust gas from the calciner 510C, as described herein) is represented schematically as also having three CO2 streams: the calcined CO2 stream 505C, the combustion CO2 stream 517C, and the biogenic CO2 stream 511C. All three CO2 streams represent CO2 captured from the atmosphere.

[0164] Therefore, all of the total CO2 production capacity of the DAC system 500C is captured atmospheric CO2. For the purposes of illustration, the capture subsystem 542C(running at the same capacity as the capture subsystem 542A of FIG. 5 A) produces 1.0 Mt / year of CO2 from the atmosphere, which is represented by the calcined CO2 stream 505C in FIG. 5C. Again for the purposes of illustration, the calciner 510C using more biogas may produce approximately 0.4 Mt / year of CO2 from combusting the biogenic methane and 0.3 Mt / year of biogenic CO2, which is represented by the combustion CO2 stream 517C and the biogenic CO2 stream 511 in FIG. 5C. Thus the total production capacity of the DAC system 500C is 1.7 Mt of CO2 per year, which is greater than the nameplate capacity of both the DAC system 500A of FIG. 5A and the DAC system 500B of FIG. 5B. The calciner 510C may need to have increased capacity to accommodate the increased total production capacity of the DAC system 500C.

[0165] As with the DAC system 500B, all or nearly all of the 1.7 Mt / year of CO2 removed from the atmosphere by the DAC system 500C can receive full carbon emissions credits, because of the use of the biogas stream 101 S in the DAC system 500C (assuming zero or negligeable embedded emissions for the biogas stream 101 S). Furthermore, like the DAC system 500B, the DAC system 500C is able to get carbon emission credits for all or nearly all of its total production capacity of 1.7 Mt / year of CO2 that it has physically removed from the atmosphere.

[0166] The description, features, reference numbers and advantages of the calciner 310, 310A, 310B, 310C provided in relation to FIGS. 3 and 4 apply mutatis mutandis to the calciner 510B, 510C of FIGS. 5B and 5C.

[0167] As explained above and shown in Table 1, the chemical composition in percent volume of the biogas streams 101 S may vary depending on the source of its biomass 102. In particular, the calorific value of the biogas stream 101 S varies depending on the amount of biogenic methane. Similarly, the amount of biogenic CO2 in the biogas stream 101 S supplied to the calciner 310, 310A, 310B, 310C, 510B, 510C may vary, and this may impact the total production of atmospheric CChby the DAC system 400, 500B, 500C. Therefore, if it is desired to maintain a consistent production capacity of atmospheric CO2 by the DAC system 400, 500B, 500C, the components and features of the DAC system 400, 500B, 500C can be operated to vary their output based on the composition of the biogas stream 101S. In the present disclosure, the term “amount” may refer to a quantity or a characteristic of the biogenic methane or of the biogenic CO2. For example, the amount of biogenic methane in the biogas stream 101 S may refer to the mass or volume of biogenic methane in a quantity of the biogas stream 101S. For example, the amount of biogenic methane in the biogas stream 101S may refer to the calorific value or chemically-stored energy of the biogas stream 101 S. For example,the amount of biogenic CO2 in the biogas stream 101 S may refer to the mass or volume of CO2 in a quantity of the biogas stream 101S. The amount of biogenic methane or the amount of biogenic CO2 in the biogas stream 101 S may refer to a quantity per unit time, such as volume per unit time or mass per unit time. The amount of biogenic methane or the amount of biogenic CO2 in the biogas stream 101 S may be determined using any suitable sensor, such as any sensor which employs gas chromatography.

[0168] One technique for accommodating variations in the amount of biogenic CO2 fed to the calciner 310, 310A, 310B, 310C, 510B, 510C is to vary the amount of the solid carbonate material 301, 501 provided to the calciner 310, 310A, 310B, 310C, 510B, 510C. The solid carbonate material 301, 501 is a store or reserve of atmospheric CO2 in solid form that is obtained from the capture subsystem 542A, 542B, 542C. It can be provided to, or withheld from, the calciner 310, 310 A, 310B, 310C, 510B, 510C depending on the CO2 production needs of the DAC system 400, 500B, 500C. This management of CO2 from the capture subsystem 542A, 542B, 542C may include adjusting the flow of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C based on the amount of the biogenic CO2 in the biogas stream 101 S. This can include increasing the flow of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C when the amount of the biogenic CO2 in the biogas stream 101 S decreases, as this would indicate that the product CO2 stream 508F, 508BF, 508CF contains less biogenic CO2 and needs to be made up with calcined CO2. Similarly, adjusting the flow of the solid carbonate material 301, 501 can include decreasing the flow of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C when the amount of the biogenic CO2 in the biogas stream 101 S increases, as this would indicate that the product CO2 stream 508F, 508BF, 508CF contains more biogenic CO2 and thus there is less need for calcined CO2.

[0169] Adjusting the flow of the solid carbonate material 301, 501 can include siloing or buffering, by temporarily storing and periodically emptying the solid carbonate material 301, 501 to / from solid silos, bins, tanks, reservoirs, or other solids storage receptacles positioned upstream of the calciner 310, 310A, 310B, 310C, 510B, 510C. Thus, when the amount of the biogenic CO2 in the biogas stream 101 S increases, the calciner 310, 310A, 310B, 310C, 510B, 510C will require less CO2 from the capture subsystem 542A, 542B, 542C, and these storage receptacles can be filled with the solid carbonate material 301, 501 to keep the embedded atmospheric CO2 in reserve. Similarly, when the amount of the biogenic CO2 in the biogas stream 101 S decreases, the calciner 310, 310A, 310B, 310C, 510B, 510C will require more CO2 from the capture subsystem 542A, 542B, 542C, and these storage receptacles can bedischarged of their solid carbonate material 301, 501 so that the calciner 310, 310A, 310B, 310C, 51 OB, 5 IOC can release the embedded atmospheric CO2 via calcination of the solid carbonate material 301, 501.

[0170] As an alternative to buffering or siloing, or in conjunction therewith, adjusting the flow of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C can include adjusting the flow rate of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C based on the amount of the biogenic CO2 in the biogas stream 101 S . For example, the flow rate of the solid carbonate material 301, 501 measured, for example, as a unit of mass per unit of time, can be decreased when the amount of the biogenic CO2 in the biogas stream 101 S increases. Similarly, the flow rate of the solid carbonate material 301, 501 can be increased when the amount of the biogenic CO2 in the biogas stream 101 S decreases.

[0171] Another technique for accommodating variations in the amount of biogenic CO2 fed to the calciner 310, 310A, 310B, 310C, 510B, 510C is to vary the amount of the CO2 captured at the “front end” of the DAC system 400, 500B, 500C, e.g., with the capture subsystem542B, 542C. Using this technique, the flow of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C is adjusted by adjusting CO2 captured from the atmospheric air and the resulting formation of the solid carbonate material 301, 501 by the capture subsy stem542B, 542C. This can be achieved in different ways. For example, in implementations where the capture subsystem542B, 542C includes one or more gas-liquid contactors or one or more air contactors, one or more of these units may be turned off or run at lower capacity to produce less solid carbonate material 301, 501, when the amount of the biogenic CO2 in the biogas stream 101 S increases. It is thus possible for the DAC system 400, 500B, 500C to adjust CO2 capture to match, or in consideration of, the biogenic CO2 content of the biogas stream 101S. In example implementations, this technique of adjusting CO2 captured from the atmospheric air and the resulting formation of the solid carbonate material 301, 501 is used in conjunction with the buffering or siloing technique described above, and / or with the technique described above of adjusting the flow rate of the solid carbonate material 301, 501 based on the amount of the biogenic CO2 in the biogas stream 101S. This combination of techniques may allow for a rapid adjustment in the feed of the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510B, 510C, thereby helping accommodate any delays while the “front end” capture subsystem542B, 542C takes time to adjust the amount of CO2 captured from the atmospheric air based on the biogenic CO2 content in the biogas stream 101S.

[0172] Thus, if it is desired to maintain a consistent production capacity of atmosphericCChby the DAC system 400, 500B, 500C, the preceding techniques show that the DAC system 400, 500B, 500C allows for dynamic adjustment of the atmospheric CO2 fed to the calciner 310, 310A, 310B, 310C, 510B, 510C based on the biogenic CO2 content in the biogas stream 101S. This controllable dynamic between the “front end” of the DAC system 400, 500B, 500C (e.g., the capture subsystem542B, 542C) and its “back end” (e.g., the calciner 310, 310A, 310B, 310C, 510B, 510C) allows the DAC system 400, 500B, 500C to use biogas with variable biogenic CO2 content, thereby increasing the number of biomass 102 feedstocks that can be used to provide the biogas stream 101 S used in the DAC system 400, 500B, 500C. The DAC system 400, 500B, 500C may thus be able to operate with any composition of the biogas stream 101 S, where an inverse relationship is formed between the biogenic CO2 content of the biogas stream 101 S and the atmospheric CO2 captured in the capture subsystem542B, 542C. This flexibility of the DAC system 400, 500B, 500C allows it to accommodate variations in the availability of the biogas stream 101 S, whose production levels and biogenic CO2 content can vary seasonally and by source of biomass 102.

[0173] Another technique for accommodating variations in the chemical composition of the biogas streams 101 S is to vary the feed of solid carbonate material 301, 501 based on the content of biogenic methane in the biogas stream 101 S. Calcining an amount of the solid carbonate material 301, 501 requires an amount of energy which comes from the biogenic methane. This management of CO2 from the capture subsystem 542A, 542B, 542C may include adjusting the flow of the solid carbonate material 301, 501 to the calciner 310, 510A ,510B, 510C based on the amount of the biogenic methane in the biogas stream 101S. When the amount of the biogenic methane in the biogas stream 101 S increases, more energy is available in the calciner 310, 510A ,510B, 510C for calcination, such that the flow of the solid carbonate material 301, 501 to the calciner 310, 510A ,510B, 510C can be increased. In this situation of a “rich” biogas stream 101 S, more calcined CO2 is produced which can help to compensate for the lower amount of biogenic CO2 in the rich biogas stream 101S. Similarly, when the amount of the biogenic methane in the biogas stream 101 S decreases, less energy is available in the calciner 310, 510A ,510B, 510C for calcination, such that the flow of the solid carbonate material 301, 501 to the calciner 310, 510A, 510B, 510C can be decreased. In this situation of a “lean” biogas stream 101 S, less calcined CO2 would be produced but could be offset by the increased amount of biogenic CO2 in the lean biogas stream 101 S. This technique allows the amount of solid carbonate material 301, 501 fed to the calciner 310, 510A, 510B, 510C to match the energy available in the biogenic methane.

[0174] In light of the preceding, it will be appreciated that the calciner 310, 310A, 31 OB, 3 IOC, 51 OB, 5 IOC of the present disclosure can operate with many or all biogas stream 101 S sources, from both:1) an impurity perspective, by capturing / preventing the impurities from being present in problematic quantities in the calciner exhaust, as described above, and2) a compositional perspective, in that dynamic adjustment between the front and / or back ends of the DAC system 400, 500B, 500C helps to accommodate variations in the amount of biogenic CO2 and / or in the amount of biogenic methane in the biogas stream.

[0175] It will be appreciated that the above-described dynamic adjustment between the front and / or back ends of the DAC system 400, 500B, 500C may not be needed, or may be needed less, where the CO2 production capacity of the DAC system 400, 500B, 500C is permitted to vary. In such implementations where the CO2 production capacity of the DAC system 400, 500B, 500C is permitted to vary, the variations in the composition of the biogas stream 101 S may lead to variations in the CO2 content of the exhaust gas stream 308, 508BF, 508CF.

[0176] Referring to FIG. 6, there is disclosed a method 600 of capturing CO2 from atmospheric air. At 602, the method 600 includes capturing CO2 from the atmospheric air and generating the solid carbonate material 301, 501 using the capture subsystem542B,542C of the DAC system 400, 500B, 500C. The solid carbonate material 301, 501 has a first CO2 removal value that is representative of a first amount of CO2 removed from the atmospheric air using the capture subsystem 542A, 542B, 542C. The solid carbonate material 301, 501 generated in the capture subsystem 542A, 542B, 542C can be considered a carrier of CO2 that has been removed from the atmosphere. The first CO2 removal value is thus an amount, typically expressed as a mass (kg, tonnes, lbs, etc.) of atmospheric CO2 that is embedded or fixed in the solid carbonate material 301, 501. The first CO2 removal value may be one of the properties of the solid carbonate material 301, 501, other properties being its density, moisture content, granularity, hardness, etc.

[0177] At 604, the method 600 includes flowing the biogas stream 101 S to a reactor 210, such as the calciner 310, 310A, 310B, 310C, 510B, 510C. The biogenic CCh ofthe biogas stream 101 S has a second CO2 removal value that is representative of a second amount of CO2 removed from the atmospheric air by a portion of the biomass 102 that has been processed into the biogas stream 101S. The CO2 of the biogenic CO2 has been captured from the atmosphere and is separate from the atmospheric CO2 embedded in the solid carbonate material 301, 501. The CO2 of the biogenic CO2 is derived from the processing of a portion the biomass 102.Processing the remainder of the biomass 102 embeds the remaining carbon molecules of the biomass 102 in the biogenic methane. The CO2 of the biogenic CO2 represents a removal of atmospheric CO2, rather than an avoidance of CO2 emissions, because the CO2 of the biogenic CO2 was taken from the atmosphere during photosynthesis of the biomass 102. The second CO2 removal value is an amount, typically expressed as a mass (kg, tonnes, lbs, etc.), of the biogenic CO2. Flowing the biogas stream 101 S to the reactor 210 at 604 may be done to a reactor 210 of the DAC system 400, 500B, 500C. In an alternate implementation, at 604, the biogas stream 101 S is flowed to a reactor 210 that is physically spaced from the DAC system 400, 500B, 500C, or which is not co-located with the DAC system 400, 500B, 500C.

[0178] At 606, the method 600 includes flowing the solid carbonate material 301, 501 to the reactor 210 using any suitable solids conveyance or transport technique. At 608, the method 600 includes combusting the biogenic methane in the reactor 210 to generate heat and a combustion CO2. The combustion CO2 has a third CO2 removal value that is representative of a third amount of CO2 that has been removed from the atmospheric air by a remainder of the biomass 102 processed into the biogas stream 101S. Combusting the biogenic methane allows its embedded carbon molecules, being of atmospheric origin, to form CO2, thereby releasing the remaining carbon molecules from the biomass 102 that produced the biogas stream 101 S. The third CO2 removal value is an amount, typically expressed as a mass (kg, tonnes, lbs, etc.), of the combustion CO2.

[0179] The CO2 of the biogenic CO2 and of the combustion CO2 represents a removal of atmospheric CO2, rather than an avoidance of CO2 emissions, because the carbon molecules of this CO2 were taken from the atmosphere during photosynthesis of the biomass 102. Similarly, the CO2 embedded in the solid carbonate material 301, 501 represents a removal of atmospheric CO2, rather than an avoidance of CO2 emissions, because the carbon molecules of this CO2 were taken from the atmosphere by the capture subsystem542B, 542C. It will be appreciated that the second CO2 removal value of the biogenic CO2 and the third CO2 removal value of the combustion CO2 exclude the trace or negligeable amounts of impurities which may be present in the biogas stream 101S. The second and third CO2 removal values may be one of the properties of their associated CO2 gas streams, other properties being their temperature, pressure, etc.

[0180] At 610, the method 600 includes calcining the solid carbonate material 301, 501 and generating the calcined CO2 and the solid oxide material 303, 503. At 612, the method 600 includes flowing the exhaust gas stream 308 from the reactor 210. The exhaust gas stream 308 includes the combustion CO2, the biogenic CO2 and the calcined CO2. At 614, the method 600includes processing the combustion CO2, the biogenic CO2 and the calcined CO2 to form the product CO2 stream 208F, 508BF, 508CF. The product CO2 stream 208F, 508BF, 508CF has a final CO2 removal value. The final CO2 removal value is the sum of the other CO2 removal values, and thus includes some or all of each of the first CO2 removal value, the second CO2 removal value, and the third CO2 removal value. The processing at 614 may include any of the processing techniques disclosed herein, including any one of purifying, compressing, and / or storing (in reservoirs, via mineralization, or in a solid and / or chemical product).

[0181] The method 600 may allow for the DAC system 400, 500B, 500C to process more CO2 removed from atmosphere than is present in the solid carbonate material 301, 501 alone, by calcining with the biogas stream 101S.

[0182] Referring to FIG. 7, there is disclosed a method 700 of capturing CO2 from atmospheric air. At 702, the method 700 includes flowing the biogas stream 101 S to the reactor 210 (such as the calciner 310, 310A, 310B, 310C, 510B, 510C). The biogenic CO2 has a first biogas carbon removal value that is representative of CO2 that was removed from the atmospheric air by a portion of the biomass 102 processed into the biogas stream 101S. The description of 604 of the method 600 of FIG. 6 applies mutatis mutandis to 702 of method 700 of FIG. 7.

[0183] At 704, the method 700 includes flowing the solid carbonate material 301, 501 to the reactor 210. The solid carbonate material 301, 501 embeds CO2 removed from the atmospheric air, and has a solids carbon removal value that is representative of CO2 removed from the atmosphere and embedded in the solid carbonate material 301, 501. The description of 602 of the method 600 of FIG. 6 applies mutatis mutandis to 704 of method 700 of FIG. 7.

[0184] At 706, the method 700 includes combusting the biogenic methane of the biogas stream 101 S in the reactor 210 to generate heat and the combustion CO2. The combustion CO2 has a second biogas carbon removal value that is representative of CO2 that was removed from the atmospheric air by a remainder of the biomass 102 processed into the biogas stream 101S. The description of 608 of the method 600 of FIG. 6 applies mutatis mutandis to 706 of method 700 of FIG. 7.

[0185] At 708, the method 700 includes calcining the solid carbonate material 301, 501 with the heat of combustion and generating the calcined CO2 and the solid oxide material 303, 503. At 710, the method 700 includes flowing the exhaust gas stream 308 from the reactor 210. The exhaust gas stream 308 comprises the combustion CO2, the biogenic CO2 and the calcined CO2. The exhaust gas stream 308 has a final carbon removal value that is representative of the CO2 present in the combustion CO2, the biogenic CO2 and the calcined CO2. The final carbonremoval value is greater than each of the first biogas carbon removal value, the second biogas carbon removal value, and the solids carbon removal value on their own. In example implementations, the final carbon removal value is the sum of the first biogas carbon removal value, the second biogas carbon removal value and the solids carbon removal value. The description of 614 of the method 600 of FIG. 6 applies mutatis mutandis to 710 of method 700 of FIG. 7.

[0186] It can be determined how much greenhouse gas (e.g., in grams of carbon dioxide equivalent emissions) is emitted by a particular process. In many contexts it is useful to determine the life-cycle greenhouse gas emissions for a particular process considering all emissions sources associated with the process itself, but also those upstream and downstream of the process. Lifecycle analysis (LCA) provides an analytic framework for such emissions determinations. The result for a DAC process is often referred to as the net amount of CO2 captured from atmosphere, which can be a measure of the lifecycle carbon dioxide emission intensity of a DAC process, or simply carbon intensity (CI). In the context of determining the CI of a DAC process, lifecycle analysis can be conceptualized as a system of accounting for CO2 flows to and from the atmosphere over the lifecycle of the DAC process, wherein CO2 flows to the atmosphere can represent emissions debits and CO2 flows from the atmosphere can represent emissions credits. The lifecycle CI of a DAC process which combusts natural gas derived from fossil fuels may need to consider the CO2 flows to the atmosphere (e.g., debits) resulting from the activities associated with the natural gas that occur upstream of the DAC process, such as extraction, transportation, and refinement of the natural gas. By using the biogas stream 101 S in the DAC system 400, 500B, 500C disclosed herein, it may be possible to reduce or eliminate the CO2 flows to the atmosphere (e.g., debits) associated with using natural gas derived from fossil fuels, thereby lowering the CI of the DAC system 400, 500B, 500C.

[0187] Referring to FIG. 8, there is disclosed a method 800 for reducing the carbon emissions intensity of the DAC system 400, 500B, 500C. In example implementations, the method 800 contributes to reducing the carbon emission intensity of an existing or already- operating DAC system 400, 500B, 500C. In other implementations, the method 800 contributes to reducing the carbon emission intensity of a DAC system 400, 500B, 500C that will be constructed. At 802, the method 800 includes flowing the biogas stream 101 S to the calciner 310, 310A, 310B, 310C, 510B, 510C. In an implementation, the biogas stream 101 S is flowed to the calciner 310, 310A, 310B, 310C, 510B, 510C instead of flowing a fossil fuel natural gas stream to the calciner. At 804, the method 800 includes flowing the solid carbonate material301, 501 to the calciner 310, 310A, 31 OB, 3 IOC, 51 OB, 5 IOC. The method 800 includes producing the product CO2 stream 208F, 508F, 508BF, 508CF from the DAC system 400, 500B, 500C. This is achieved by combusting the biogenic methane in the calciner 310, 310A, 31 OB, 3 IOC, 51 OB, 5 IOC to generate heat and the combustion CO2 (step 806), calcining the solid carbonate material 301, 501 and generating the calcined CO2 and the solid oxide material 303, 503 (step 808), flowing the exhaust gas stream 308 from the calciner 310, 310A, 310B, 3 IOC, 51 OB, 5 IOC (step 810), where the exhaust gas stream 308 has the combustion CO2, the biogenic CO2 and the calcined CO2, and processing the exhaust gas stream 308 to form the product CO2 stream 208F,508F, 508BF, 508CF (step 812). The DAC system 400, 500B, 500C using the biogas stream 101 S as described in method 800 may have a lower carbon emissions intensity, or CI, compared to if the same DAC system combusted fossil-fuel natural gas in the calciner.

[0188] The methods, systems and apparatuses disclosed herein may allow for generating emission credits. In example implementations, each emission credit represents a unit of greenhouse gas removed from the atmosphere. In example implementations, each emission credit represents a unit of greenhouse gas whose emission to the atmosphere has been avoided. Each emission credit may be a transferrable financial instrument that represents an emission reduction, and it can be bought, sold, leveraged or otherwise treated as a financial security. An emission credit may also represent a direct payment, made by one entity to another entity who generates the emission credit. One example of an emission credit is a carbon credit, where one carbon credit represents the reduction or removal of one ton of carbon dioxide or its equivalent in other greenhouse gases, expressed as tonnes of carbon dioxide equivalent (CO2e). Such credits may be generated for use in compliance with government mandated regulations or markets, or for sale to voluntary purchasers of such credits.

[0189] Referring to FIG. 9, there is disclosed a method 900 for generating emissions credits. In example implementations of the method 900, the emission credits represent a unit of greenhouse gas removed from the atmosphere. In example implementations of the method 900, the emission credits represent a unit of avoided greenhouse gas emissions to the atmosphere. At 902, the method 900 includes generating a first emissions credit by combusting in the calciner 310, 310A, 310B, 310C, 510B, 510C biogenic methane of the biogas stream 101 S. The biogas stream 101 S may be provided by a biogas production facility, or by any other facility that provides combustible gas from feedstocks deemed to be renewable. Non-limiting examples of such alternate combustible gases include renewable ammonia sourced from atmospheric nitrogen and green hydrogen, and synthetic gas (syngas) generated from municipalsolid waste. In its unrefined state, the biogas stream 101 S may already have, or be representative of, or include, an emission credit associated with avoiding emission to the atmosphere of the biogenic methane produced from the biomass 102. Heat and the combustion CO2 stream 317, 517, 517B, 517C are generated in the calciner 310, 310A, 31 OB, 310C, 51 OB, 510C by combusting the biogenic methane, such that the biogenic methane is converted into CO2. The conversion of the biogenic methane into CO2 results in the generation of the first emissions credit because the biogenic methane generated from the biomass 102 is converted to a less potent greenhouse gas, which is the CO2 of the combustion CO2 stream 317, 517, 517B, 517C. At 902 the first emissions credit is still generated even if the combustion CO2 stream 317, 517, 517B, 517C is vented to atmosphere, because the vented CO2 has less global warming potential than its erstwhile biogenic methane form would have if vented to atmosphere. The method also includes storing the CO2 of the combustion CO2 stream 317, 517, 517B, 517C, as described in more detail below. In example implementations, this storing of the CO2 of the combustion CO2 stream 317, 517, 517B, 517C may result in another emissions credit in addition to the first emissions credit.

[0190] At steps 904-910, the method 900 includes generating a second emissions credit. The second emissions credit is generated by capturing CO2, thereby removing it from the atmosphere. To generate the second emissions credit, the solid carbonate material 301, 501 is calcined in the calciner 310, 310A, 310B, 310C, 510B, 5 IOC to release its embedded CO2 that has been removed from atmospheric air to form a calcined CO2 stream 305, 505, 505C that is released from the solid carbonate material 301, 501, and the solid oxide material 303, 503 (step 904). The exhaust gas stream 308, 508 flowed from the calciner 310, 310A, 310B, 310C, 510B, 510C includes the combustion CO2 stream 317, 517, 517B, 517C, the biogenic CO2 stream 311, 511, 511C, and the calcined CO2 stream 305, 505, 505C (step 906). The exhaust gas stream 308, 508 is processed to form the product CO2 stream 508F, 508BF, 508CF (step 908). The product CO2 stream 508F, 508BF, 508CF is stored in any suitable manner to durably fix the carbon molecules, thereby removing the CO2 of the product CO2 stream 508F, 508BF, 508CF from the atmosphere (step 910). Storing the CO2 of the product CO2 stream 508F, 508BF, 508CF may be achieved using one or more of the processing techniques disclosed herein, including any one of compressing the purified CO2 stream, and storing the purified CO2 stream (in reservoirs, via mineralization, or in a solid or chemical product). The value or worth of the second emissions credit may depend on the nature, duration and extent of the stored CO2. For example, the value or worth of the second emissions credit may be less if the CO2 is temporarily stored by converting it into a chemical product, compared to if the secondemissions credit represents the more permanent storage of CO2 in a reservoir. In example implementations, both the first and second emissions credits are generated at the location of, or by, the DAC system 400, 500A, 500B, 500C, irrespective of how the emissions credits are transacted after they are generated.

[0191] The types of emissions credits and where they are generated pursuant to the method 900 may be better understood with reference to FIG. 9A. The harvesting and / or collection of the biomass 102, and / or its transport to the production platform 104 for generating the biogas stream 101 S, generates emissions of greenhouse gases to atmosphere. The biomass 102 therefore has biomass embedded emissions 102E. The production platform 104 may also generate emissions of greenhouse gases to atmosphere when producing the biogas stream 101 S, such that the production platform 104 has production platform embedded emissions 104E. The biogas stream 101S has embedded biogas emissions 101SE. The embedded biogas emissions 101 SE are equal to the biomass embedded emissions 102E plus the production platform embedded emissions 104E. The embedded emissions may be expressed or measured using any suitable units, for example, unit mass per unit of energy of the combustible methane. For example, if the biomass embedded emissions 102E are X g / MJ, and the production platform embedded emissions 104E are Y g / MJ, then the embedded biogas emissions 101SE are equal to (X+Y) g / MJ. The method 900 of FIG. 9 may include generating a third emissions credit 104T. The third emissions credit 104T is generated by producing the biogas stream 101 S in the production platform 104. By processing the biomass 102 to capture the products of its decomposition (biogenic methane and biogenic CO2) and preventing these products from being emitted to the atmosphere, the production platform 104 generates the third emissions credit 104T by preventing or avoiding biogenic methane, which is a potent greenhouse gas. The third emissions credit 104T is thus an avoidance emission credit, and is representative of an amount of avoided greenhouse gas emissions (e.g., avoided methane emissions) to atmosphere. In implementations where the third emissions credit 104T represents an amount of avoided methane emissions, the third emissions credit 104T may be transacted (e.g., sold) via exchanges and / or markets that are separate from those transacting CO2 removal credits. In example implementations, the third emissions credit 104T represents an amount of avoided greenhouse gas emissions that is greater than the embedded biogas emissions 101SE. In example implementations, the third emissions credit 104T represents an amount of avoided greenhouse gas emissions that is an order of magnitude greater than the embedded biogas emissions 101 SE.

[0192] Referring to FIG. 9A, the second emissions credit 922 may be generated by the DAC system 400, 500A, 500B, 500C. In example implementations, the second emissions credit922 is a removal emission credit, and is representative of removing, from the atmosphere, the CO2 of at least the calcined CO2 and the biogenic CO2. In implementations where the combustion CO2 stream is stored, the second emissions credit 922 can also be representative of removing the CO2 of the combustion CO2 from the atmosphere. The second emissions credit 922 may be referred to, or may constitute, a removal emission credit. The atmospheric CO2 removals represented by the second emission credit 922 include at least: the atmospheric CO2 embedded in the solid carbonate material 301, 501 when the solid carbonate material 301, 501 is formed in the capture subsystem 542B, 542C, and the atmospheric CO2 of the biogenic CO2 and of the combustion CO2 that are stored with the product CO2 508F, 508BF, 508CF. In example implementations, the first emissions credit 921 generated by combusting the biogenic methane in the calciner at 902 of the method 900 is an avoidance emission credit because it represents an amount of avoided biogenic methane emissions to atmosphere. In implementations where the combustion CO2 is stored at 910 of the method 900, the first emissions credit 921 is a removal emission credit because it represents the removal of the carbon embedded in the biogenic methane from the atmosphere.

[0193] In at least one alternate implementation of the method 900, each emission credit represents a unit of greenhouse gas removed from the atmosphere, or a unit of emissions avoided. The method 900 may generate credits in both the removal and avoidance categories, or may combine such credits into a single aggregate stream of credits.

[0194] Referring to FIG. 10, there is disclosed a method 1000 of capturing CO2 from the biogas stream 101 S. At 1002, the method 1000 includes flowing the biogas stream 101 S to the reactor 210, 310, 310A, 310B, 310C, 510B, 510C. At 1004, the method 1000 includes combusting the biogenic methane of the biogas stream 101 S in the reactor 210, 310, 310A, 310B, 310C, 510B, 510C and generating a combustion CO2 205, 317, 517, 517B, 517C. At 1006, the method 1000 includes flowing an exhaust gas stream 208, 308, 508, 508BF, 508CF, 2108 from the reactor 210, 310, 310A, 310B, 310C, 510B, the exhaust gas stream 208, 308, 508, 508BF, 508CF, 2108 comprising the combustion CO2205, 317, 517, 517B, 517C and the biogenic CO2 211, 311, 511, 511 C. At 1008, the method 1000 includes processing the combustion CO2205 , 317, 517, 517B, 517C and the biogenic CO2211 , 311 , 511 , 511 C of the exhaust gas stream 208, 308, 508, 508BF, 508CF, 2108 to form the product CO2 stream 208F, 508F, 508BF, 508CF.

[0195] Referring to FIG. 11, there is disclosed a method 1100 of capturing carbon dioxide (CO2) from atmospheric air. At 1102, the method 1100 includes capturing the CO2 from the atmospheric air and generating the solid carbonate material 301, 501. At 1104, themethod 1100 includes flowing the biogas stream 101 S to the calciner 310, 310A, 31 OB, 310C, 510A, 510B, 510C. At 1106, the method 1100 includes flowing the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 3 IOC, 510A, 51 OB, 5 IOC. At 1108, the method 1100 includes combusting the biogenic methane of the biogas stream 101 S in the calciner 310, 310 A, 310B, 310C, 510A, 510B, 510C to generate heat and a combustion CO2317, 517, 517B, 517C, and calcining the solid carbonate material 301, 501 and generating the calcined CO2305, 505, 505C and the solid oxide material 303, 503. At 1110, the method 1100 includes flowing the exhaust gas stream 308, 508, 508BF, 508CF, 2108 from the calciner 310, 310A, 310B, 310C, 510A, 510B, 5 IOC, the exhaust gas stream comprising the combustion CO2317, 517, 517B, 517C, the biogenic CO2 311, 511, 511C and the calcined CCh 305, 505, 505C. At 1112, the method 1100 includes processing the combustion CO2317, 517, 517B, 517C, the biogenic CO2 311, 511, 511C and the calcined CO2305, 505, 505C to form the product CO2 stream 508F, 508BF, 508CF.

[0196] Referring to FIG. 12, there is disclosed a method 1200 of capturing CO2 from atmospheric air (e.g. atmospheric air 1603 of FIG. 4). At 1202, the method 1200 includes capturing the CO2 from the atmospheric air and generating the solid carbonate material 301, 501. At 1204, the method 1200 includes flowing a biomethane stream (e.g., a stream of the biomethane 106 disclosed herein) to the calciner 310, 310A, 310B, 310C, 510A, 510B, 510C. At 1206, the method 1200 includes flowing the solid carbonate material 301, 501 to the calciner 310, 310A, 310B, 310C, 510A, 510B, 510C. At 1208, the method 1200 includes combusting the biomethane stream 106 in the calciner 310, 310A, 310B, 3 IOC, 510A, 51 OB, 5 IOC to generate heat and the combustion CO2317, 517, 517B, 517C, and calcining the solid carbonate material 301, 501 and generating the calcined CO2305, 505, 505C and a solid oxide material 303, 503. At 1201, the method 1200 includes flowing the exhaust gas stream 308, 508, 508BF, 508CF, 2108 from the calciner 310, 310A, 310B, 310C, 510A, 510B, 510C, the exhaust gas stream comprising the combustion CCh 317, 517, 517B, 517C, the biogenic CO2 311, 511, 511C and the calcined CO2305, 505, 505C. At 1212, the method 1200 includes processing the combustion CO2317, 517, 517B, 517C, the biogenic CO2311 , 511 , 511 C and the calcined CO2 305, 505, 505C to form the product CO2 stream 508F, 508BF, 508CF.

[0197] The reactor 210, calciner 310, 310A, 310B, 310C, 510A, 510B, 510C and / or DAC system 400, 500A, 500B, 500C can also include a control system (or flow control system) (e.g., control system 999 of FIG. 3) that is integrated with and / or communicably coupled with one or more components of the reactor 210, calciner 310, 310A, 310B, 310C, 510A, 510B, 510C and / or DAC system 400, 500A, 500B, 500C. For example, the process streams in thereactor 210, calciner 310, 310A, 310B, 310C, 510A, 510B, 510C and / or DAC system 400, 500A, 500B, 500C can be flowed using one or more flow control systems (e.g., control system 999) implemented throughout the reactor 210, calciner 310, 310A, 310B, 310C, 510A, 510B, 510C and / or DAC system 400, 500A, 500B, 500C. A flow control system can include one or more flow pumps, fans, blowers, or solids conveyors to move the process streams, one or more flow pipes through which the process streams are flowed and one or more valves to regulate the flow of streams through the pipes. Each of the configurations described herein can include at least one variable frequency drive (VFD) coupled to a respective pump that is capable of controlling at least one liquid flow rate. In example implementations, liquid flow rates are controlled by at least one flow control valve.

[0198] In some embodiments, a flow control system can be operated manually. For example, an operator can set a flow rate for each pump or transfer device and set valve open or close positions to regulate the flow of the process streams through the pipes in the flow control system. Once the operator has set the flow rates and the valve open or close positions for all flow control systems distributed across the system, the flow control system can flow the streams under constant flow conditions, for example, constant volumetric rate or other flow conditions. To change the flow conditions, the operator can manually operate the flow control system, for example, by changing the pump flow rate or the valve open or close position.

[0199] In some embodiments, a flow control system can be operated automatically. For example, the flow control system can be connected to a computer or control system (e.g., control system 999) to operate the flow control system. The control system can include a computer-readable medium storing instructions (such as flow control instructions and other instructions) executable by one or more processors to perform operations (such as flow control operations). An operator can set the flow rates and the valve open or close positions for all flow control systems distributed across the facility using the control system. In such embodiments, the operator can manually change the flow conditions by providing inputs through the control system. Also, in such embodiments, the control system can automatically (that is, without manual intervention) control one or more of the flow control systems, for example, using feedback systems connected to the control system. For example, a sensor (such as a pressure sensor, temperature sensor or other sensor) can be connected to a pipe through which a process stream flows. The sensor can monitor and provide a flow condition (such as a pressure, temperature, or other flow condition) of the process stream to the control system. In response to the flow condition exceeding a threshold (such as a threshold pressure value, a threshold temperature value, or other threshold value), the control system can automaticallyperform operations. For example, if the pressure or temperature in the pipe exceeds the threshold pressure value or the threshold temperature value, respectively, the control system can provide a signal to the pump to decrease a flow rate, a signal to open a valve to relieve the pressure, a signal to shut down process stream flow, or other signals.

[0200] FIG. 13 is a schematic diagram of a control system (or controller) 1500, which may be used for example with reactor 210, calciner 310, 310A, 310B, 310C, 510A, 510B, 510C and / or DAC system 400, 500A, 500B, 500C. The control system 1500 can be used for the operations described in association with any of the computer-implemented methods described previously, for example as or as part of the control system 999 or other controllers described herein. For example, the control system 1500 may be used to control flows of the biogas stream 1012 and / or of the solid carbonate material 501 based on the dynamic adjustment between the front and / or back ends of the DAC system 400, 500B, 500C described above, to accommodate variations in the amount of biogenic CO2 and / or in the amount of biogenic methane in the biogas stream.

[0201] The control system 1500 is intended to include various forms of digital computers, such as laptops, desktops, workstations, personal digital assistants, servers, blade servers, mainframes, and other appropriate computers. The control system 1500 can also include mobile devices, such as personal digital assistants, cellular telephones, smartphones, and other similar computing devices. Additionally the system can include portable storage media, such as, Universal Serial Bus (USB) flash drives. For example, the USB flash drives may store operating systems and other applications. The USB flash drives can include input / output components, such as a wireless transmitter or USB connector that may be inserted into a USB port of another computing device.

[0202] The system 1500 includes a processor 510, a memory 520, a storage device 530, and an input / output device 1540. Each of the components 510, 520, 530, and 1540 are interconnected using a system bus 1550. The processor 510 is capable of processing instructions for execution within the control system 1500. The processor may be designed using any of a number of architectures. For example, the processor 510 may be a CISC (Complex Instruction Set Computers) processor, a RISC (Reduced Instruction Set Computer) processor, or a MISC (Minimal Instruction Set Computer) processor.

[0203] In one implementation, the processor 510 is a single-threaded processor. In example implementations, the processor 510 is a multi -threaded processor. The processor 510 is capable of processing instructions stored in the memory 520 or on the storage device 530 to display graphical information for a user interface on the input / output device 1540.

[0204] The memory 520 stores information within the control system 1500. In one implementation, the memory 520 is a computer-readable medium. In one implementation, the memory 520 is a volatile memory unit. In example implementations, the memory 520 is a nonvolatile memory unit.

[0205] The storage device 530 is capable of providing mass storage for the control system 1500. In one implementation, the storage device 530 is a computer-readable medium. In various different implementations, the storage device 530 may be a floppy disk device, a hard disk device, an optical disk device, or a tape device.

[0206] The input / output device 1540 provides input / output operations for the control system 1500. In one implementation, the input / output device 1540 includes a keyboard and / or pointing device. In example implementations, the input / output device 1540 includes a display unit for displaying graphical user interfaces.

[0207] In example implementations, the processor 510 is configured to execute a machine learning model (e.g., an artificial intelligence model) that employs multiple layers of models to generate an output for a received input. A deep neural network is a deep machine learning model that includes an output layer and one or more hidden layers that each apply a non-linear transformation to a received input to generate an output. In some cases, the neural network may be a recurrent neural network. A recurrent neural network is a neural network that receives an input sequence and generates an output sequence from the input sequence. In particular, a recurrent neural network uses some or all of the internal state of the network after processing a previous input in the input sequence to generate an output from the current input in the input sequence. The machine learning model executed by the processor 510 can be, for example, a deep-leaming neural network or a "very" deep learning neural network. For example, the machine learning model executed by the processor 510 can be a convolutional neural network or a recurrent network. The machine learning model can have residual connections or dense connections.

[0208] In example implementations, the machine learning model executed by the processor 510 is an ensemble of models that may include all or a subset of the architectures described above.

[0209] In example implementations, the machine learning model executed by the processor 510 is a graph neural network (GNN). GNNs are a designed to process data that can be represented in a graph form and feature pairwise message passing to enable iterative updating of node representation of the graph data.

[0210] In example implementations, the machine learning model executed by the processor 510 can be a feedforward auto-encoder neural network. For example, the machine learning model executed by the processor 510 can be a three-layer auto-encoder neural network. The machine learning model executed by the processor 510 may include an input layer, a hidden layer, and an output layer. In example implementations, the neural network has no recurrent connections between layers. Each layer of the neural network may be fully connected to the next, e.g., there may be no pruning between the layers. The neural network may include an optimizer for training the network and computing updated layer weights. In example implementations, the neural network may apply a mathematical transformation, e.g., a convolutional transformation or factor analysis to input data prior to feeding the input data to the network.

[0211] In example implementations, the machine learning model executed by the processor 510 can be a supervised model. For example, for each input provided to the model during training, the machine learning model can be instructed as to what the correct output should be. The machine learning model executed by the processor 510 can use batch training, e.g., training on a subset of examples before each adjustment, instead of the entire available set of examples. This may improve the efficiency of training the model and may improve the generalizability of the model. In example implementations, the machine learning model executed by the processor 510 may be an unsupervised model. For example, the model may adjust itself based on mathematical distances between examples rather than based on feedback on its performance. In example implementations, the machine learning model executed by the processor 510 can provide suggested additional data that could further improve the output of the machine learning model.

[0212] Certain features described can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. The apparatus can be implemented in a computer program product tangibly embodied in an information carrier, e.g., in a machine-readable storage device for execution by a programmable processor; and method steps can be performed by a programmable processor executing a program of instructions to perform functions of the described implementations by operating on input data and generating output. The described features can be implemented advantageously in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. A computer program is a set of instructions that can be used, directly or indirectly, in a computer to performa certain activity or bring about a certain result. A computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.

[0213] Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors of any kind of computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memories for storing instructions and data. Generally, a computer will also include, or be operatively coupled to communicate with, one or more mass storage devices for storing data files; such devices include magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and optical disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magnetooptical disks; and CD-ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits).

[0214] To provide for interaction with a user, the features can be implemented on a computer having a display device such as a CRT (cathode ray tube) or LCD (liquid crystal display) monitor for displaying information to the user and a keyboard and a pointing device such as a mouse or a trackball by which the user can provide input to the computer. Additionally, such activities can be implemented via touchscreen flat-panel displays and other appropriate mechanisms.

[0215] The features can be implemented in a control system (such as control system 999) that includes a back-end component, such as a data server, or that includes a middleware component, such as an application server or an Internet server, or that includes a front-end component, such as a client computer having a graphical user interface or an Internet browser, or any combination of them. The components of the system can be connected by any form or medium of digital data communication such as a communication network. Examples of communication networks include a local area network (“LAN”), a wide area network (“WAN”), peer-to-peer networks (having ad-hoc or static members), grid computing infrastructures, and the Internet.

[0216] The term “couple” and variants of it such as “coupled,” “couples,” and “coupling” as used in this description is intended to include indirect and direct connections unless otherwise indicated. For example, if a first device is coupled to a second device, that coupling may be through a direct connection or through an indirect connection via other devices and connections. Similarly, if the first device is communicatively coupled to the second device, communication may be through a direct connection or through an indirect connection via other devices and connections. In particular, a fluid coupling means that a direct or indirect pathway is provided for a fluid to flow between two fluidly coupled devices. Also, a thermal coupling means that a direct or indirect pathway is provided for heat energy to flow between to thermally coupled devices.

[0217] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features specific to particular implementations s. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

[0218] Similarly, while operations are depicted in the drawings in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

[0219] A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims. Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art in view of this description. Accordingly, this descriptionis to be construed as illustrative only. It is to be understood that the forms shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described herein without departing from the spirit and scope as described in the following claims.

Claims

WHAT IS CLAIMED IS:

1. A method of capturing carbon dioxide (CO2) from a biogas stream, the method comprising: flowing the biogas stream to a reactor, the biogas stream comprising biogenic methane and biogenic CO2; combusting the biogenic methane of the biogas stream in the reactor and generating a combustion CO2; flowing an exhaust gas stream from the reactor, the exhaust gas stream comprising the combustion CO2 and the biogenic CO2; and processing the combustion CO2 and the biogenic CO2 of the exhaust gas stream to form a product CO2 stream.

2. The method of claim 1, wherein: flowing the biogas stream to the reactor comprises flowing the biogas stream to a calciner; and combusting the biogenic methane of the biogas stream in the reactor comprises combusting the biogenic methane in the calciner.

3. The method of claim 2, further comprising calcining a solid carbonate material in the calciner.

4. The method of claim 3, wherein; calcining the solid carbonate material comprises generating a calcined CO2; and processing the biogenic CO2 and the combustion CO2 comprises processing the combustion CO2, the biogenic CO2, and the calcined CChto form the product CO2 stream.

5. The method of claim 3 or 4, wherein: flowing the biogas stream to the calciner comprises flowing the biogas stream with impurities including hydrogen sulfide (H2S); and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCCh) and generating a calcium oxide (CaO) product; reacting some of at least one of the CaCOs and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product; and separating at least a portion of the at least one of the solid sulphite product and the solid sulphate product from the CaO product.

6. The method of claim 3 or 4, wherein flowing the biogas stream to the calciner comprises flowing the biogas stream with impurities; and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities.

7. The method of any one of claims 1 to 6, wherein processing the combustion CO2 and the biogenic CO2 comprises sequestering the product CO2 stream in a reservoir.

8. The method of any one of claims 1 to 6, wherein processing the combustion CO2 and the biogenic CO2 comprises mineralizing the product CO2 stream to form a solid material.

9. The method of any one of claims 1 to 6, wherein processing the combustion CO2 and the biogenic CO2 comprises providing the product CO2 stream as a feedstock for forming a chemical product.

10. The method of any one of claims 1 to 6, wherein processing the combustion CO2 and the biogenic CO2 comprises: cooling the exhaust gas stream to form a cooled exhaust gas stream; purifying the cooled exhaust gas stream to form a purified CO2 stream; and compressing the purified CO2 stream to form the product CO2 stream.

11. The method of any one of claims 1 to 10, wherein combusting the biogenic methane of the biogas stream in the reactor comprises oxy-firing the biogenic methane.

12. A reaction system, comprising: a piping network comprising a biogas pipeline configured to flow a biogas stream comprising 45%-75% of biogenic methane and 25%-55% of biogenic carbon dioxide (CO2); and a reactor configured to combust the biogenic methane of the biogas stream and generate heat and a combustion CO2, the reactor comprising: an interior; at least one inlet in fluid communication with the interior, the at least one inlet comprising a biogas inlet in fluid communication with the biogas pipeline and configured to provide the biogas stream to the interior; and at least one outlet in fluid communication with the interior, the at least one outlet comprising an exhaust gas outlet configured to convey an exhaust gas stream from the interior, the exhaust gas stream comprising the combustion CO2 and the biogenic CO2.

13. The reaction system of claim 12, wherein: the at least one inlet comprises a solids inlet configured to provide a solid carbonate material to the interior; the reactor is configured to calcine the solid carbonate material and generate a calcined CO2 and a solid oxide material; the exhaust gas outlet is configured to convey the calcined CO2 from the interior; and the at least one outlet comprises a solids outlet configured to convey the solid oxide material from the interior.

14. The reaction system of claim 13, wherein: the solids inlet is configured to provide the solid carbonate material to the interior to form a bed of the solid carbonate material; and the biogas inlet is configured to provide the biogas stream to fluidize the bed of the solid carbonate material.

15. The reaction system of any one of claims 12 to 14, wherein the at least one inlet comprises an oxygen inlet configured to provide an oxygen stream to the reactor.

16. A method of capturing carbon dioxide (CO2) from atmospheric air, the method comprising: capturing the CO2 from the atmospheric air and generating a solid carbonate material; flowing a biogas stream to a calciner, the biogas stream comprising biogenic methane and biogenic CO2; flowing the solid carbonate material to the calciner; combusting the biogenic methane of the biogas stream in the calciner to generate heat and a combustion CO2, and calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream comprising the combustion CO2, the biogenic CO2 and the calcined CO2; and processing the combustion CO2, the biogenic CO2 and the calcined CO2 to form a product CO2 stream.

17. The method of claim 16, wherein: flowing the biogas stream to the calciner comprises flowing the biogas stream with impurities including hydrogen sulfide (H2S); and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCCh) and generating a calcium oxide (CaO) product; and reacting some of at least one of the CaCOs and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product.

18. The method of claim 16, wherein: flowing the biogas stream to the calciner comprises flowing the biogas stream with impurities; and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCCh) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities.

19. The method of any one of claims 16 to 18, wherein flowing the solid carbonate material to the calciner comprises adjusting a flow of the solid carbonate material to the calciner based on an amount of the biogenic CO2 in the biogas stream.

20. The method of claim 19, wherein adjusting the flow of the solid carbonate material to the calciner comprises increasing the flow of the solid carbonate material to the calciner when the amount of the biogenic CO2 in the biogas stream decreases.

21. The method of claim 19 or 20, wherein adjusting the flow of the solid carbonate material to the calciner comprises: filling at least one receptacle with the solid carbonate material upstream of the calciner when the amount of the biogenic CO2 in the biogas stream increases; and discharging the solid carbonate material from the at least one receptacle and to the calciner when the amount of the biogenic CO2 in the biogas stream decreases.

22. The method of any one of claims 19 to 21, wherein: flowing the solid carbonate material to the calciner comprises flowing the solid carbonate material to the calciner at a solid carbonate material flow rate; and adjusting the flow of the solid carbonate material to the calciner comprises adjusting the solid carbonate material flow rate based on the amount of the biogenic CO2 in the biogas stream.

23. The method of any one of claims 19 to 22, wherein adjusting the flow of the solid carbonate material to the calciner comprises adjusting the capturing of the CO2 from the atmospheric air and the generating the solid carbonate material.

24. The method of any one of claims 16 to 18, wherein flowing the solid carbonate material to the calciner comprises adjusting a flow of the solid carbonate material to the calciner based on an amount of the biogenic methane in the biogas stream.

25. The method of any one of claims 16 to 24, wherein processing the combustion CO2, the biogenic CO2 and the calcined CO2 comprises sequestering the product CO2 stream in a reservoir.

26. The method of any one of claims 16 to 24, wherein processing the combustion CO2, the biogenic CO2 and the calcined CO2 comprises mineralizing the product CO2 stream to form a solid material.

27. The method of any one of claims 16 to 26, wherein processing the combustion CO2, the biogenic CO2 and the calcined CO2 comprises providing the product CO2 stream as a feedstock for forming a chemical product.

28. The method of any one of claims 16 to 27, wherein processing the combustion CO2, the biogenic CO2 and the calcined CO2 comprises: cooling the exhaust gas stream to form a cooled exhaust gas stream; purifying the cooled exhaust gas stream to form a purified CO2 stream; and compressing the purified CO2 stream to form the product CO2 stream.

29. The method of any one of claims 16 to 28, wherein combusting the biogenic methane of the biogas stream in the calciner comprises oxy-firing the biogenic methane.

30. A system for capturing carbon dioxide (CO2) from atmospheric air, the system comprising: at least one gas-liquid contactor operable to absorb at least a portion of the CO2 from the atmospheric air into a capture solution; at least one carbonate-forming reactor in fluid communication with the at least one gasliquid contactor, the at least one carbonate-forming reactor operable to react the capture solution with calcium hydroxide to form solid calcium carbonate (CaCCh); a calciner in communication with the at least one carbonate-forming reactor, the calciner comprising: an interior; at least one inlet in fluid communication with the interior, the at least one inlet comprising a biogas inlet configured to provide a biogas stream to the interior, and a solids inlet configured to provide the solid CaCCh from the at least one carbonate-forming reactor; and at least one outlet in fluid communication with the interior, the at least one outlet comprising an exhaust gas outlet; the calciner configured to: combust biogenic methane representing 45%-75% of the biogas stream and generate heat and a combustion CO2, and calcine the solid CaCOs and generating a calcined CO2 and a solid oxide material; and flow an exhaust gas stream from the interior through the exhaust gas outlet, the exhaust gas stream comprising the combustion CO2, the calcined CO2 and biogenic CO2 representing 25%-55% of the biogas stream.

31. The system of claim 30, further comprising at least one receptacle upstream of the calciner and configured to receive the solid CaCCh from the at least one carbonate-forming reactor, and configured to discharge the solid CaCCh to the calciner.

32. The system of claim 30 or 31, further comprising: a cooling unit in fluid communication with the exhaust gas outlet and configured to reduce a water vapor content of the exhaust gas stream and form a cooled exhaust gas stream; a purification unit in fluid communication with the cooling unit and configured to purify the cooled exhaust gas stream and form a purified CO2 stream; and a compressor unit in fluid communication with the purification unit and configured to compress the purified CO2 stream and form a product CO2 stream.

33. The system of claim of any one of claims 30 to 32, wherein the at least one inlet comprises an oxygen inlet configured to flow oxygen to the interior.

34. The system of claim of any one of claims 30 to 33, wherein the calciner includes one of: a rotary calciner, a circulating fluidized bed calciner, a gravity -fed calciner, and a flash calciner.

35. The system of claim 30, wherein the calciner includes a flash calciner.

36. A system for capturing carbon dioxide (CO2) from atmospheric air, the system comprising: at least one air contactor operable to contact at least a portion of the CO2 from the atmospheric air with a sorbent to form a solid carbonate material; and a calciner in communication with the at least one air contactor, the calciner comprising: an interior; at least one inlet in fluid communication with the interior, the at least one inlet comprising a biogas inlet configured to provide a biogas stream to the interior, and a solids inlet configured to provide the solid carbonate material from the at least one air contactor; and at least one outlet in fluid communication with the interior, the at least one outlet comprising an exhaust gas outlet; the calciner configured to: combust biogenic methane representing 45%-75% of the biogas stream and generate heat and a combustion CO2, and calcine the solid carbonate material and generating a calcined CO2 and a solid oxide material; and flow an exhaust gas stream from the interior through the exhaust gas outlet, the exhaust gas stream comprising the combustion CO2, the calcined CO2 and biogenic CO2 representing 25%-55% of the biogas stream.

37. The system of claim 36, further comprising at least one receptacle upstream of the calciner and configured to receive solid CaCOs from the at least one carbonate-forming reactor, and configured to discharge the solid CaCCh to the calciner.

38. The system of claim 36 or 37, further comprising: a cooling unit in fluid communication with the exhaust gas outlet and configured to reduce a water vapor content of the exhaust gas stream and form a cooled exhaust gas stream; a purification unit in fluid communication with the cooling unit and configured to purify the cooled exhaust gas stream and form a purified CO2 stream; and a compressor unit in fluid communication with the purification unit and configured to compress the purified CO2 stream and form a product CO2 stream.

39. The system of claim of any one of claims 36 to 38, wherein the at least one inlet comprises an oxygen inlet configured to flow oxygen to the interior.

40. The system of claim of any one of claims 36 to 39, wherein the calciner includes one of: a rotary calciner, a circulating fluidized bed calciner, a gravity -fed calciner, and a flash calciner.

41. The system of claim of any one of claims 36 to 39, wherein the calciner includes a flash calciner.

42. A method of capturing carbon dioxide (CO2) from atmospheric air, the method comprising: capturing CO2 from the atmospheric air and generating a solid carbonate material using a capture subsystem of a Direct Air Capture (DAC) system, the solid carbonate material having a first CO2 removal value representative of a first amount of CO2 removed from the atmospheric air using the capture subsystem; flowing a biogas stream to a reactor, the biogas stream comprising biogenic methane and biogenic CO2, the biogenic CO2 of the biogas stream having a second CO2 removal value representative of a second amount of CO2 removed from the atmospheric air by a portion of a biomass processed into the biogas stream; flowing the solid carbonate material to the reactor; combusting the biogenic methane of the biogas stream in the reactor to generate heat and a combustion CO2, the combustion CO2 having a third CO2 removal value representative of a third amount of CO2 removed from the atmospheric air by a remainder of the biomass processed into the biogas stream; calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the reactor, the exhaust gas stream comprising the combustion CO2, the biogenic CO2 and the calcined CO2; and processing the exhaust gas stream to form a product CO2 stream, the product CO2 stream having a final CO2 removal value, the final CO2 removal value including at least a portion of each of the first CO2 removal value, the second CO2 removal value, and the third CO2 removal value.

43. The method of claim 42, wherein: flowing the biogas stream to the reactor comprises flowing the biogas stream with impurities including hydrogen sulfide (H2S); and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCCh) and generating a calcium oxide (CaO) product; and reacting some of at least one of the CaCOs and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product.

44. The method of claim 42, wherein: flowing the biogas stream to the reactor comprises flowing the biogas stream with impurities; and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities.

45. The method of any one of claims 42 to 44, wherein flowing the solid carbonate material to the reactor comprises adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic CO2 in the biogas stream.

46. The method of claim 45, wherein adjusting the flow of the solid carbonate material to the reactor comprises increasing the flow of the solid carbonate material to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

47. The method of claim 45 or 46, wherein adjusting the flow of the solid carbonate material to the reactor comprises: filling at least one receptacle with the solid carbonate material upstream of the reactor when the amount of the biogenic CO2 in the biogas stream increases; and discharging the solid carbonate material from the at least one receptacle and to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

48. The method of any one of claims 45 to 47, wherein flowing the solid carbonate material to the reactor comprises flowing the solid carbonate material to the reactor at a solid carbonate material flow rate; and adjusting the flow of the solid carbonate material to the reactor comprises adjusting the solid carbonate material flow rate based on the amount of the biogenic CO2 in the biogas stream.

49. The method of any one of claims 45 to 48, wherein adjusting the flow of the solid carbonate material to the reactor comprises adjusting the capturing the CO2 from the atmospheric air and the generating the solid carbonate material.

50. The method of any one of claims 42 to 44, wherein flowing the solid carbonate material to the reactor comprises adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic methane in the biogas stream.

51. The method of any one of claims 42 to 50, wherein processing the exhaust gas stream comprises sequestering the product CO2 stream in a reservoir.

52. The method of any one of claims 42 to 51, wherein processing the exhaust gas stream comprises mineralizing the product CO2 stream to form a solid material.

53. The method of any one of claims 42 to 52, wherein processing the exhaust gas stream comprises providing the product CO2 stream as a feedstock for forming a chemical product.

54. The method of any one of claims 42 to 53, wherein processing the exhaust gas stream comprises: cooling the exhaust gas stream to form a cooled exhaust gas stream; purifying the cooled exhaust gas stream to form a purified CO2 stream; and compressing the purified CO2 stream to form the product CO2 stream.

55. The method of any one of claims 42 to 54, wherein combusting the biogenic methane of the biogas stream in the reactor comprises oxy-firing the biogenic methane.

56. The method of claim 42, further comprising adjusting the final CO2 removal value by at least one of: adjusting a flow of the solid carbonate material to the reactor; and adjusting the capturing the CO2 from the atmospheric air and the generating the solid carbonate material.

57. A method of capturing carbon dioxide (CO2) from atmospheric air, the method comprising: flowing a biogas stream to a reactor, the biogas stream comprising biogenic methane and biogenic CO2, the biogenic CO2 having a first biogas carbon removal value representative of CO2 removed from the atmospheric air by a portion of a biomass processed into the biogas stream; flowing a solid carbonate material to the reactor, the solid carbonate material embedding CO2 removed from the atmospheric air, the solid carbonate material having a solids carbon removal value representative of CO2 removed from the atmosphere and embedded in the solid carbonate material; combusting the biogenic methane of the biogas stream in the reactor to generate heat and a combustion CO2, the combustion CO2 having a second biogas carbon removal value representative of CO2 removed from the atmospheric air by a remainder of the biomass processed into the biogas stream; calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; and flowing an exhaust gas stream from the reactor, the exhaust gas stream comprising the combustion CO2, the biogenic CO2 and the calcined CO2, the exhaust gas stream having a final carbon removal value representative of the CO2 present in the combustion CO2, the biogenic CO2 and the calcined CO2, the final carbon removal value being greater than each of the first biogas carbon removal value, the second biogas carbon removal value, and the solids carbon removal value on their own.

58. The method of claim 57, wherein: flowing the biogas stream to the reactor comprises flowing the biogas stream with impurities including hydrogen sulfide (H2S); and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCCh) and generating a calcium oxide (CaO) product; and reacting some of at least one of the CaCCh and the CaO product with the H2S and generating at least one of a solid sulphite product and a solid sulphate product.

59. The method of claim 57, wherein: flowing the biogas stream to the reactor comprises flowing the biogas stream with impurities; and calcining the solid carbonate material comprises: calcining calcium carbonate (CaCOs) and generating a calcium oxide (CaO) product; and at least one of: reacting some of at least one of the CaCOs and the CaO product with a first portion of the impurities and generating a solid product; and combusting a second portion of the impurities60. The method of any one of claims 57 to 59, wherein flowing the solid carbonate material to the reactor comprises adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic CO2 in the biogas stream.

61. The method of claim 60, wherein adjusting the flow of the solid carbonate material to the reactor comprises increasing the flow of the solid carbonate material to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

62. The method of claim 60 or 61, wherein adjusting the flow of the solid carbonate material to the reactor comprises: filling at least one receptacle with the solid carbonate material upstream of the reactor when the amount of the biogenic CO2 in the biogas stream increases; and discharging the solid carbonate material from the at least one receptacle and to the reactor when the amount of the biogenic CO2 in the biogas stream decreases.

63. The method of any one of claims 60 to 62, wherein: flowing the solid carbonate material to the reactor comprises flowing the solid carbonate material to the reactor at a solid carbonate material flow rate; and adjusting the flow of the solid carbonate material to the reactor comprises adjusting the solid carbonate material flow rate based on the amount of the biogenic CO2 in the biogas stream.

64. The method of any one of claims 57 to 59, wherein flowing the solid carbonate material to the reactor comprises adjusting a flow of the solid carbonate material to the reactor based on an amount of the biogenic methane in the biogas stream.

65. The method of any one of claims 57 to 64, further comprising processing the exhaust gas stream by: cooling the exhaust gas stream to form a cooled exhaust gas stream; purifying the cooled exhaust gas stream to form a purified CO2 stream; and compressing the purified CO2 stream to form a product CO2 stream.

66. The method of any one of claims 57 to 65, wherein combusting the biogenic methane of the biogas stream in the reactor comprises oxy-firing the biogenic methane.

67. A method for reducing a carbon emissions intensity of a direct air capture (DAC) system, the method comprising: flowing a biogas stream to a calciner of the DAC system, the biogas stream comprising biogenic methane and biogenic CO2; flowing a solid carbonate material to the calciner; producing a product CO2 stream from the DAC system by: combusting the biogenic methane of the biogas stream in the calciner to generate heat and a combustion CO2; calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream comprising the combustion CO2, the biogenic CO2 and the calcined CO2; and processing the exhaust gas stream to form the product CO2 stream; wherein the DAC system has a lower carbon emissions intensity compared to if the DAC system combusted fossil-fuel natural gas in the calciner.

68. A method for generating emissions credits, the method comprising: generating a first emissions credit by combusting in a calciner biogenic methane of a biogas stream that also includes biogenic CO2, combustion of the biogenic methane in the calciner generating heat and a combustion CO2; and generating a second emissions credit by: calcining in the calciner a solid carbonate material embedding CO2 removed from atmospheric air, to form a calcined CO2 released from the solid carbonate material, and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream comprising the combustion CO2, the biogenic CO2 and the calcined CO2; processing the exhaust gas stream to form a product CO2 stream; and storing at least some of the product CO2 stream.

69. The method of claim 68, wherein generating the first emissions credit comprises venting at least some of the combustion CO2 to atmosphere.

70. The method of claim 68 or 69, further comprising generating a third emissions credit by producing the biogas stream comprising the biogenic methane and the biogenic CO2.

71. The method of claim 70, wherein the third emissions credit is an avoidance emissions credit representative of an amount of avoided methane emissions to atmosphere.

72. The method of any one of claims 68 to 71, wherein the second emissions credit is a removal emissions credit representative of removing CO2 of at least the calcined CO2 and the biogenic CO2 from atmosphere.

73. The method of any one of claims 68 to 72, wherein storing the at least some of the product CO2 stream comprises sequestering the product CO2 stream in a reservoir.

74. The method of any one of claims 68 to 73, wherein: generating the first emissions credit comprises generating the first emissions credit at a direct air capture (DAC) system; and generating the second emissions credit comprises generating the second emissions credit at the DAC system.

75. A calciner, comprising: an interior; at least one inlet in fluid communication with the interior, the at least one inlet comprising a biogas inlet configured to provide to the interior a biogas stream comprising 45 %- 75% of biogenic methane and 25%-55% of biogenic carbon dioxide (CO2), and a solids inlet configured to provide a solid carbonate material to the interior; at least one outlet in fluid communication with the interior, the at least one outlet comprising an exhaust gas outlet; and at least one burner configured to combust the biogenic methane and generate heat in the interior and a combustion CO2, wherein: the solid carbonate material is configured to calcine in the interior and generate a calcined CO2 and a solid oxide material; and an exhaust gas stream is configured to flow from the interior through the exhaust gas outlet, the exhaust gas stream comprising the combustion CO2, the calcined CO2 and the biogenic CO2.

76. A method of capturing carbon dioxide (CO2) from atmospheric air, the method comprising: capturing the CO2 from the atmospheric air and generating a solid carbonate material; flowing a biomethane stream to a calciner; flowing the solid carbonate material to the calciner; combusting the biomethane stream in the calciner to generate heat and a combustion CO2, and calcining the solid carbonate material and generating a calcined CO2 and a solid oxide material; flowing an exhaust gas stream from the calciner, the exhaust gas stream comprising the combustion CO2, biogenic CO2 and the calcined CO2; and processing the combustion CO2, the biogenic CO2 and the calcined CO2 to form a product CO2 stream.

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