Dual fuel engine operating strategy for optimizing hydrogen and hydrocarbon fueling

Abstract

Operating an engine system (10) includes combusting gaseous hydrogen fuel (H2) and gaseous hydrocarbon fuel (HC) in a cylinder (16) of an engine (12) at a first substitution ratio, determining at least one of an H2 fueling command or an HC fueling command based on an H2 availability input and an H2 cost, and outputting the H2 fueling command and the HC fueling command to an H2 injector (66) and an HC inlet valve (56), respectively. Operating the engine system also includes combusting H2 and HC with a change alternative ratio based on the H2 fueling command and the HC fueling command. At least one of the H2 fueling command or the HC fueling command may be based on a monitored CO2 exhaust level that may be used to fill a stored history of the CO2 output.

Description

[0001] Government Interest Statement

[0002] This invention was made with government support under Contract DE-EE0009422 awarded by DOE. The government has certain rights in this invention. Technical Field

[0003] The present disclosure relates generally to operating an internal combustion engine using gaseous hydrogen and gaseous hydrocarbon fuels, and more particularly to operating the engine with a hydrogen to hydrocarbon substitution ratio based on hydrogen availability and cost. Background Art

[0004] Internal combustion engines are well known and widely used around the world for purposes ranging from vehicle propulsion to pump and compressor operations and for power generation. For example, in the oil and gas industry, internal combustion engines are essential for providing power for gas compression, fluid delivery and power generation. Internal combustion engine design and operation are undergoing a revolution as investors, markets and various stakeholders increasingly expect producers, manufacturers and service providers to limit certain emissions generated by internal combustion engines on site. In particular, carbon emissions associated with various operations are a growing concern and planning strategies to reduce carbon emissions are underway.

[0005] The use of hydrogen as a fuel source for traditional hydrocarbon-based engine platforms provides prospects for reducing certain emissions (especially carbon). The use of gaseous hydrogen fuel in traditional reciprocating internal combustion engines provides significant advantages over efforts to convert to electric devices or other complex solutions. However, the use of gaseous hydrogen fuel as a practical replacement or supplement for traditional hydrocarbon-based fuels provides many different engineering and technical challenges. Recently, manufacturers have begun to explore strategies for operating traditional reciprocating engines using hydrogen or hydrogen-rich fuels. An arrangement utilizes an internal combustion engine that is designed to operate with gaseous hydrocarbon fuels (such as methane or natural gas) supplemented with gaseous hydrogen. Due to factors such as the uncertain availability of hydrogen and the challenges in adjusting internal electronic controls to optimally operate the engine under flexible fuel types, strategies for mixing hydrogen and hydrocarbon fuels have not yet realized their full theoretical potential. U.S. Patent Application No. 17552717 relates to cost-based substitution ratio control in an internal combustion engine system that can provide hydrogen. Summary of the invention

[0006] In one aspect, a method of operating an internal combustion engine system includes: combusting gaseous hydrogen fuel (H2) and gaseous hydrocarbon fuel (HC) in a cylinder of the engine at a first substitution ratio; receiving an H2 availability input; and determining at least one of an H2 fueling command or an HC fueling command based on the H2 availability input and an H2 cost. The method also includes: outputting the H2 fueling command and the HC fueling command to an H2 injector and an HC admission valve, respectively, each coupled to an intake system of the engine; and combusting H2 and HC in the cylinder at a varying substitution ratio based on the H2 fueling command and the HC fueling command.

[0007] On the other hand, an internal combustion engine system includes an engine having a plurality of cylinders formed therein and having a plurality of pistons, each of which can reciprocate in one of the plurality of cylinders. The engine system also includes a gaseous hydrogen fuel (H2) injector and a gaseous hydrocarbon fuel (HC) admission valve. The engine system also includes an intake system and a fuel filling control system, the intake system being configured to deliver a mixture containing H2, HC and air to the plurality of cylinders. The fuel filling control system includes at least one electronic control unit in control communication with the H2 injector and the HC admission valve. The at least one electronic control unit is configured to determine at least one of an H2 fuel filling command or an HC fuel filling command based on at least one of a feed rate or a storage amount of H2 and an H2 cost. The at least one electronic control unit is also configured to output the H2 fuel filling command and the HC fuel filling command to the H2 injector and the HC admission valve, respectively, to change a substitution ratio of H2 to HC burned in the plurality of cylinders.

[0008] In yet another aspect, a fueling control system for a dual gaseous hydrogen fuel (H2) and gaseous hydrocarbon fuel (HC) engine includes at least one electronic control unit configured to receive an H2 availability input indicating at least one of an H2 feed rate or an H2 storage amount, and receive an H2 cost input indicating an H2 cost. The at least one electronic control unit is further configured to determine each of an H2 fueling command and an HC fueling command based on the H2 availability input and the H2 cost input, and output the H2 fueling command and the HC fueling command to an H2 injector and an HC admission valve, respectively. The at least one electronic control unit is further configured to change a substitution ratio of H2 to HC combusted in a plurality of cylinders of the engine based on the H2 fueling command and the HC fueling command. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of an internal combustion engine system according to one embodiment;

[0010] Figure 2 is a functional block diagram of a fuel filling control system according to one embodiment; and

[0011] Figure 3 is a flowchart illustrating an exemplary method and logic flow according to one embodiment. DETAILED DESCRIPTION

[0012] Reference Figure 1 , shows a dual fuel internal combustion engine system 10 according to one embodiment. The engine system 10 includes an engine having an engine housing 14, in which a plurality of combustion cylinders 16 are formed, and the engine has a plurality of pistons 18, each of which can reciprocate in one of the cylinders 16. The engine 12 can include any number of cylinders in any suitable arrangement, such as in-line, V-type, etc. The engine 12 is coupled to a drive shaft 42, which can rotate to provide power to a load 46 through a clutch 44 and potentially through a transmission (not shown). In one embodiment, the load 46 includes a generator that provides power to operate an electric device such as an electric motor 48 or to supply a power grid. The engine 12 can be applied to generate rotational power for a generator, a pump, a compressor, a drive train in a mobile vehicle (such as a truck or a ship) as shown, or for almost any other conceivable purpose. In a typical configuration, the engine 12 is spark-ignited, and each cylinder 16 can be equipped with a spark ignition device, such as a pre-chamber spark plug (not shown).

[0013] The engine system 10 also includes an intake system 20 having an air inlet 22 and an intake conduit 24 extending to an intake manifold 28. Intake air flows from the air inlet 22 through a compressor 31 in a turbocharger 32 and into the intake manifold 28 through an aftercooler 26. The suction side of the compressor 31 refers to a location in the intake system 20 that is fluidly located between the compressor 31 and the air inlet 22, and the pressure side of the compressor 31 refers to a location in the intake system 20 that is fluidly located between the compressor 31 and the cylinders 16. A plurality of intake ports 30 are formed in the engine housing 14, fluidly located between the intake manifold 28 and the cylinders 16. The engine system 10 also includes an exhaust system 34 having an exhaust conduit 36 ​​that extends, for example, through an exhaust manifold (not numbered) to a turbine 38 in the turbocharger 32, and then to an exhaust outlet 40, such as an exhaust pipe or tail pipe. As discussed further herein, intake system 20 is configured to deliver a mixture including gaseous hydrogen fuel (H2), gaseous hydrocarbon fuel (HC), and compressed air to cylinder 16. Exhaust system 34 is configured to deliver exhaust gas from the combustion of H2, HC, and air to exhaust outlet 40.

[0014] The engine system 10 also includes a fuel system 50 that includes an HC supply 52. ​​In one embodiment, the HC supply 52 may include a pipeline gas HC supply, such as may be available at a wellhead, a mine, or other location where a supply of gaseous HC (e.g., natural gas, methane, ethane, biogas, mixtures, etc.) is expected to be continuously or at least predictably available. In other embodiments, the HC supply 52 may include a compressed gaseous HC supply, a cryogenically stored liquefied gaseous HC supply coupled to a vaporizer, or another supply capable of producing or providing HC. A filter or other treatment device 54 may be fluidly positioned between the HC supply 52 and an HC port 58 that is connected to the intake conduit 24 on the suction side of the compressor 31 so that HC can be supplied to the engine 12 by fumigation, as is familiar to those skilled in the art. An electrically actuated HC admission valve 56 is fluidly positioned between the HC supply 52 and the HC port 58.

[0015] The fuel system 50 also includes a H2 supply 60. In one embodiment, the H2 supply 60 includes a pressurized storage tank or the like containing gaseous molecular hydrogen or a hydrogen-rich gaseous fuel mixture. H2 can be supplied to the H2 supply 60 from any of a variety of sources. For example, a chemical plant may produce hydrogen as a byproduct of a manufacturing process, wherein the produced hydrogen is collected and pressurized to be stored in the H2 supply 60. Other H2 sources may include a hydrogen reformer or a device for collecting H2 from various fluid mixtures. In other cases, the engine system 10 may be connected to a hydrogen pipeline.

[0016] In any case, the availability of hydrogen, including the availability of so-called "green" hydrogen from renewable resources, may be limited due to a combination of fuel availability and distribution challenges posed by limited hydrogen infrastructure. The needs of an operator may not always be consistent with the available supply of hydrogen, for example, due to industrial sources producing hydrogen at variable or unpredictable levels, or due to limitations or unpredictability that may exist regarding the instantaneous flow rate of hydrogen that an operator can consume, limitations on total daily consumption of hydrogen, or financial constraints related to H2 cost, availability, storage and / or demand. For these and other reasons, operators such as power producers may at least sometimes utilize HC as the sole fuel or mixed with H2 to ensure that demand can be met consistently and reliably. At the same time, operators may wish to minimize or optimize the emissions footprint of the engine system, such as the greenhouse gas (GHG) footprint, while still meeting power or thermal requirements. As will be further apparent from the following description, it may be desirable to selectively switch a generator set or other operation to HC or a mixture of HC and H2, and is provided in accordance with the present disclosure.

[0017] The fuel system 50 also includes a pump 62 fluidly positioned between the H2 supply 60 and a plurality of H2 injectors 66 to pressurize the H2 to a pressure above the boost pressure and feed it to the engine 12 through the H2 supply conduit 64. In one embodiment, the H2 injectors 66 include port injectors, each located at or near the intake port 30. In other embodiments, for example, one or more of the H2 injectors may be positioned to inject the H2 into the intake manifold 28, or potentially configured as direct injectors to inject the H2 into the cylinders 16.

[0018] The engine system 10 also includes a fuel filling control system 70. The fuel filling control system 70 includes at least one electronic control unit in control communication with the H2 injector 66 and the H2 admission valve 56. In one embodiment, the at least one electronic control unit includes a fuel filling control unit 72 and a supervisory control unit 74. It should be appreciated that the functions of the fuel system control, in particular the control of the H2 to HC substitution ratio as further described herein, can be performed by a single electronic control unit, two electronic control units, or more than two electronic control units. Therefore, the description and discussion of the features or functions of any one electronic control unit herein should be understood to refer to the features or functions of any other electronic control unit in the fuel filling control system 70 by analogy. The electronic control unit as contemplated herein includes any suitable programmable logic unit, such as a microprocessor or a microcontroller.

[0019] The fuel filling control system 70 may also include an operator input interface 110 that communicates with one or both of the electronic control units 72 and 74. The operator input interface 110 may include a graphical input interface, a keyboard, a mouse, or a combination or extension of these. In some embodiments, the operator input interface 110 may be part of a maintenance tool. In the example shown, the operator input interface 110 includes an H2 availability control 112, an H2 cost control 114, a CO2 history indicator 116, and an optimization control 118. Each of the controls 112, 114, and 118 may include, for example, one or more buttons, dials, switches, graphic buttons, icons, or sliders on a display, or some other suitable structure for inputting information from and / or displaying information to an operator such as a maintenance technician.

[0020] The fuel filling control system 70 may also include an H2 sensor 61 in or associated with the H2 supply 60 and configured to generate data indicating at least one of a feed rate or a storage amount of H2. The fuel filling control system 70 may also include a CO2 sensor 63 coupled to the exhaust system 34 and configured to generate data for directly or indirectly monitoring the CO2 exhaust level of the engine 12. The H2 sensor 61 may include, for example, a pressure sensor, a flow sensor, or both. The CO2 sensor 63 may include a sensor responsive to the actual CO2 exhaust level, or a sensor such as an oxygen or lambda sensor that monitors other exhaust constituents to indirectly indicate the approximate level of CO2 in the exhaust from the engine 12. The fuel filling control system 70 may also include or be coupled to various other sensors, such as a boost pressure sensor, a cylinder pressure sensor, an engine speed sensor, an engine and / or exhaust temperature sensor, a virtual engine load sensor, and various other sensors and sensor groups (virtual or non-virtual), which are considered conventional and are not specifically shown herein.

[0021] At least one electronic control unit 72, 74 is in control communication with the H2 injector 66 and the HC admission valve 56, as described above, and is configured to determine at least one of the H2 fueling command or the HC fueling command based on at least one of the feed rate or storage amount of H2 and the H2 cost. Data indicating at least one of the feed rate or storage amount of H2 can be understood as H2 availability and can be provided by input from the H2 sensor 61. The H2 availability input to the at least one electronic control unit 72, 74 can also be generated by the H2 availability control 112 in the operator input interface 110. The at least one electronic control unit 72, 74 is also configured to output the H2 fueling command and the HC fueling command to the H2 injector 66 and the HC admission valve 56, respectively, to establish or change the replacement ratio of H2 to HC combusted in the cylinder 66.

[0022] Now also refer to Figure 2, a functional block diagram of the fuel filling control system 70 is shown. In the example shown, the fuel filling control unit 72 includes a processor 91 and a computer readable memory 92 storing an H2 map 94 and an HC map 96. The H2 map 94 and the HC map 96 may include a fuel filling map for determining a fuel filling control command and an ignition map for determining an ignition (spark) timing. In at least some embodiments, the fuel filling control unit 72 may interpolate between the H2 map 94 and the HC map 96 to determine the ignition timing based on the relative proportions of H2 and HC burned in a given engine cycle. The supervisory control unit 74 includes a processor 97 and a computer readable memory 98, which stores greenhouse gas (GHG) optimization instructions or software 100 and a stored CO2 history 102 populated by the supervisory control unit 74. The computer readable memories 92 and 98 may include any suitable volatile or non-volatile memory, such as RAM, ROM, DRAM, SDRAM, EPROM, flash memory, etc. It will be recalled that the illustrated features and functionality of the fueling control unit 72 and the supervisory control unit 74 may be integrated into a single electronic control unit or two or more electronic control units, or may be configured differently than illustrated.

[0023] Figure 2 Also depicted in FIG. 7 is a fuel fill determination input 76 received by the fuel fill control unit 72. The fuel fill determination input 76 includes an H2 availability input 78, such as may be generated by the H2 sensor 61 or the H2 availability control 112, which indicates at least one of a feed rate or a storage amount of H2. Thus, the fuel fill determination input may be "X" liters or moles of H2 per minute or hour, "Z" total liters or moles of H2 available, or some other quantitative term. The fuel fill determination input 76 may also include an engine speed input 80, an engine load input 82, and a CO2 level input 84, such as may be generated by or derived from the output of the CO2 sensor 63. The fuel fill control unit 72 outputs an H2 fuel fill command 104 and an HC fuel fill command 106 to the H2 injector 66 and the HC inlet valve 56, respectively, as discussed herein. The H2 fueling command 104 and the HC fueling command 106 , such as electrical control current commands to solenoids in the respective devices, may be used to set or adjust an alternative ratio of the mixture of H2, HC, and air combusted in the cylinder 16 .

[0024] Figure 26. Also depicted are optimization inputs 86 received by the supervisory control unit 74, including, for example, an H2 cost input that may be generated by the H2 cost control 114 or received from the H2 sensor 61, and an operator request signal 90 for H2 / HC optimization that may be generated by, for example, the optimization control 118. For example, the H2 cost input may be "Z" dollars per liter or per mole of H2, or a dimensionless numeric cost representation. Communicated between the fueling control unit 72 and the supervisory control unit 74 are a CO2 output 94 transmitted from the fueling control unit 72 to the supervisory control unit 74, and a substitution ratio offset 99 transmitted from the supervisory control unit 74 to the fueling control unit 72. The CO2 output 94 may be an instantaneous CO2 level, such as parts per million (ppm), or an average CO2 level over a duration of time.

[0025] The substitution ratio offset 99 may include a numerical offset that changes the substitution ratio of H2 to HC that would otherwise be generated by determining the H2 fueling command 104 and the HC fueling command 106 without receiving the operator input 90. For example, based on a given H2 availability and a given H2 cost, the fueling control unit 72 may determine the fueling control commands 104 and 106 to generate an H2 to HC substitution ratio of "Y" % H2. The substitution ratio offset 99 may be applied to generate an H2 to HC substitution ratio of 0.9Y%, 1.1Y%, etc., as further discussed herein.

[0026] As described above, H2 availability may be limited or may be variable and unpredictable. In some cases, it will be desirable to operate the engine system 10 with the highest possible H2 to HC replacement ratio (in other words, based on the maximum availability of H2). However, the operator may be aware of H2 costs and GHG footprint at least sometimes. The fueling control system 70 can balance these factors so that the operator can optimize engine system operation to best achieve several goals.

[0027] Typically, where H2 costs are relatively low, it may be desirable to supply H2 at the maximum available flow rate, thereby providing a relatively high H2 to HC substitution ratio. Where H2 costs are relatively high, it may be desirable to supply H2 at a flow rate less than the theoretically achievable maximum, or to not supply H2 at all. However, where H2 / CO2 is to be optimized, the desire to limit or otherwise manage CO2 output may influence and sometimes supersede or override H2 cost considerations. Operator input 90 may be understood as an operator request to optimize H2 / CO2. Where operator input 90 is received, at least one and typically both of fueling control commands 104 and 106 may be determined based on both H2 availability and CO2 levels (typically including a storage history of CO2 output over time (“GHG footprint”), and possibly also H2 costs). Where H2 costs are relatively low, optimizing H2 / CO2 may be achieved by determining fueling control commands 104 and 106 to provide the highest H2 to HC substitution ratio feasible based on H2 availability, regardless of the GHG footprint. In the event that H2 costs are not low, then optimizing H2 / CO2 may be achieved by determining the fueling control commands 104 and 106 to provide an H2 to HC substitution ratio on a sliding scale based on the GHG footprint. For example, if H2 costs are moderately high and the GHG footprint indicates that an annual CO2 output target of greater than "Q"% has been achieved, then the fueling control commands may be determined to provide an H2 to HC substitution ratio that is less than the highest feasible H2 to HC substitution ratio to a first relative degree. When H2 costs are very high and the GHG footprint indicates that an annual CO2 output target of greater than Q% has been achieved, then the fueling control commands may be determined to provide an H2 to HC substitution ratio that is less than the highest feasible H2 to HC substitution ratio to a greater relative degree. As described above, in some cases, H2 costs may not be considered at all. The supervisory control unit 74 may also include appropriate maps related to the GHG footprint, H2 costs, substitution ratio offsets, and potentially other factors, or may perform calculations to determine relative adjustments to the H2 to HC substitution ratio as contemplated herein. Given the present description, one skilled in the art will appreciate other strategies for balancing H 2 costs with CO 2 levels based on stored CO 2 history or yet other factors.

[0028] In one practical embodiment, at least one of the fueling control units 72, 74 determines the H2 command 104 and the HC command 106 based on a portion of the engine power output that will be produced by each fuel. Specifically, the fueling control unit 72 may determine the required fuel flow rate based on the lower heating value of each fuel and then establish the fuel flow rates for H2 and HC via the corresponding H2 command 104 and HC command 106. An engine speed regulator located on, for example, the fueling control unit 72 or the supervisory control unit 74 may also account for differences in shipping delays for each of the corresponding fuels. In other words, since it may take some time to increase or decrease the fuel flow rate for H2 and / or HC, the speed of the cycle calculation or other determination of at least one of the corresponding fueling commands when adjustments are to be made may account for the fact that fueling rate adjustments may not occur instantaneously by slowing down or delaying the determination.

[0029] Industrial Applicability

[0030] Reference is generally made to the accompanying drawings, but reference is now also made to Figure 3 , a flowchart 200 is shown according to one embodiment, which shows an exemplary method and logic flow. At box 210, H2 and HC are combusted in the cylinder 16 at a first substitution ratio. From box 210, the flowchart 200 advances to box 220 to receive the fuel fill determination input 76. It will be recalled that the fuel fill determination input 76 may include the H2 availability input 78. The H2 availability can be determined from a direct sensor (such as the H2 sensor 61), but can also be determined in other ways by the H2 availability control 112 and directly input by the operator.

[0031] From box 220, the flowchart 200 proceeds to box 230 to receive a GHG footprint optimization signal (operator input 90). It will also be recalled that the supervisory control unit 74 may transmit a substitution ratio offset 99 to the fueling control unit 72. In the event that a GHG footprint optimization signal is not received, or perhaps in the event that the H2 cost is high and the overall GHG footprint is low, for example, no offset or a 0% offset may be applied.

[0032] From box 230, the flowchart 200 advances to box 240 to determine the H2 command 104 and the HC command 106 based on H2 availability and other factors discussed herein, including any alternative ratio offsets to be used. From box 250, the flowchart 200 may advance to box 260 to combust H2 and HC in the cylinder 16 at a varied alternative ratio based on the H2 command 104 and the HC command 106.

[0033] This specification is for illustrative purposes only, and should not be interpreted as narrowing the scope of the present disclosure in any way. Therefore, it will be understood by those skilled in the art that, without departing from the complete and reasonable scope and spirit of the present disclosure, various modifications can be made to the embodiments disclosed herein. By viewing the accompanying drawings and the appended claims, other aspects, features and advantages will become apparent. As used herein, the articles "a" and "an" are intended to include one or more items, and can be used interchangeably with "one or more". When intended to represent only one item, the term "one" or similar language is used. In addition, as used herein, the term "has, have, having" and the like are intended to be open terms. In addition, the phrase "based on" is intended to mean "based, at least in part, on", unless otherwise expressly stated.

Claims

1. A method of operating an internal combustion engine system (10), comprising: combusting a gaseous hydrogen fuel (H2) and a gaseous hydrocarbon fuel (HC) in a cylinder (16) of an engine (12) at a first substitution ratio; Receive H2 availability input; determining at least one of an H2 fueling command or an HC fueling command based on the H2 availability input and the H2 cost; outputting the H2 fueling command and the HC fueling command to an H2 injector (66) and an HC admission valve (56) respectively, each of which is coupled to an intake system (20) of the engine; and H2 and HC are combusted in the cylinder at a changed substitution ratio based on the H2 fueling command and the HC fueling command.

2. The method according to claim 1, further comprising: monitoring a CO 2 exhaust level of the engine, and wherein at least one of a H 2 fueling command or a HC fueling command is determined based on the monitored CO 2 exhaust level; as well as A stored history of CO 2 output is populated based on monitoring CO 2 exhaust levels of the engine.

3. The method of claim 1 or 2, further comprising receiving an operator request for H2 / CO2 optimization, and wherein at least one of the H2 fueling command or the HC fueling command is determined based on the operator request for H2 / CO2 optimization.

4. The method according to any one of claims 1 to 3, wherein the HC inlet valve is fluidly connected to the intake system on the suction side of a compressor (31) of a turbocharger (32); and Wherein the H2 injector comprises an H2 port injector.

5. The method of any preceding claim, wherein determining at least one of a H2 fueling command or a HC fueling command further comprises: determining each of the H2 fueling command and the HC fueling command based on both the H2 availability input and the H2 cost; as well as Fuel flow rates for H2 and HC are established based on the lower heating values ​​of H2 and HC via corresponding H2 fueling commands and HC fueling commands, respectively.

6. An internal combustion engine system (10), comprising: an engine (12) having a plurality of cylinders (16) formed therein, and a plurality of pistons (18), each piston being reciprocatable in one of the plurality of cylinders; a gaseous hydrogen fuel (H2) injector (66); Gaseous hydrocarbon fuel (HC) inlet valve (56); an intake system (20) configured to deliver a mixture comprising H2, HC and air to the plurality of cylinders; A fuel filling control system (70) comprising at least one electronic control unit (72, 74) in control communication with the H2 injector and the HC admission valve and configured to: determining at least one of an H2 fueling command or an HC fueling command based on at least one of a feed rate or a storage amount of H2 and an H2 cost; and The H2 fueling command and the HC fueling command are output to the H2 injector and the HC admission valve, respectively, to change a substitution ratio of H2 to HC combusted in the plurality of cylinders.

7. The engine system of claim 6, wherein the at least one electronic control unit is further configured to receive an H2 availability input indicative of at least one of a feed rate or a storage amount of H2; and wherein the at least one electronic control unit is further configured to determine at least one of a H2 fueling command or a HC fueling command based on a CO2 exhaust level of the engine; The engine system further includes: An operator input interface (100), and wherein the at least one electronic control unit is further configured to receive an operator request for H2 / CO2 optimization from the operator input interface, and to determine at least one of an H2 fueling command or an HC fueling command based on the operator request for H2 / CO2 optimization.

8. The engine system of claim 6 or 7, wherein the H2 availability input indicates a maximum H2 availability; and Wherein the at least one electronic control unit is further configured to limit the H2 to HC substitution ratio based on the H2 cost.

9. An engine system according to any preceding claim, wherein the intake system further comprises a turbocharger compressor (31), and the HC admission valve is fluidly connected to the intake system on a suction side of the compressor, and wherein the H2 injector comprises an H2 port injector; and Wherein the at least one electronic control unit is further configured to determine each of the H2 fueling command and the HC fueling command to establish a fuel flow rate into the intake system based on a lower heating value of H2 and HC, respectively.

10. A fuel filling control system (70) for a dual gaseous hydrogen fuel (H2) and gaseous hydrocarbon fuel (HC) engine (12), comprising: At least one electronic control unit (72, 74), the at least one electronic control unit being configured to: receiving a H2 availability input indicating at least one of a H2 feed rate or a H2 storage amount; receiving an H2 cost input indicating an H2 cost; determining each of an H2 fueling command and an HC fueling command based on the H2 availability input and the H2 cost input; outputting the H2 fuel filling command and the HC fuel filling command to the H2 injector (66) and the HC inlet valve (56), respectively; and A substitution ratio of H2 to HC combusted in a plurality of cylinders (16) of the engine is varied based on the H2 fueling command and the HC fueling command.

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