Thermal Hydrogen Plant (with and without CCS)

Overview

Thermal Hydrogen assets in Macro represent hydrogen production technologies that use thermal processes, such as steam methane reforming (SMR) or other thermal conversion methods. These assets are defined using either JSON or CSV input files placed in the assets directory, typically named with descriptive identifiers like thermalhydrogen.json or thermalhydrogen.csv.

CCS version

Macro supports both the standard thermal hydrogen plant asset and a CCS version. The only difference between the two is the addition of a CO₂ captured edge.

Asset Structure

A thermal hydrogen plant asset consists of one transformation component and five edge components:

Transformation Component: Balances the fuel, electricity, and hydrogen flows
Fuel Edge: Incoming edge representing fuel supply (e.g., natural gas)
Electricity Edge: Incoming edge representing electricity consumption
Hydrogen Edge: Outgoing edge representing hydrogen production (can have unit commitment operations)
CO₂ Edge: Outgoing edge representing CO₂ emissions
CO₂ Captured Edge: Outgoing edge representing captured CO₂ (only if CCS is present)

Here is a graphical representation of the thermal hydrogen plant asset:

%%{init: {'theme': 'base', 'themeVariables': { 'background': '#D1EBDE' }}}%% flowchart LR subgraph ThermalHydrogen direction BT A((Fuel)) e1@--> C{{..}} B((Electricity)) e2@--> C{{..}} C{{..}} e3@--> D((Hydrogen)) C{{..}} e4@--> E((CO₂ Emitted)) C{{..}} e5@--> F((CO₂ Captured)) e1@{ animate: true } e2@{ animate: true } e3@{ animate: true } e4@{ animate: true } e5@{ animate: true } end style A r:55px,fill:#005F6A,stroke:black,color:white,stroke-dasharray: 3,5; style B r:55px,fill:#FFD700,stroke:black,color:black,stroke-dasharray: 3,5; style C r:55px,fill:black,stroke:black,color:black, stroke-dasharray: 3,5; style D font-size:21px,r:55px,fill:lightblue,stroke:black,color:black,stroke-dasharray: 3,5; style E font-size:17px,r:55px,fill:lightgray,stroke:black,color:black,stroke-dasharray: 3,5; style F font-size:15px,r:55px,fill:lightgray,stroke:black,color:black,stroke-dasharray: 3,5; linkStyle 0 stroke:#005F6A, stroke-width: 2px; linkStyle 1 stroke:#FFD700, stroke-width: 2px; linkStyle 2 stroke:lightblue, stroke-width: 2px; linkStyle 3,4 stroke:lightgray, stroke-width: 2px;

Flow Equations

The thermal hydrogen plant asset follows these stoichiometric relationships:

\[\begin{aligned} \phi_{fuel} &= \phi_{h2} \cdot \epsilon_{fuel\_consumption} \\ \phi_{elec} &= \phi_{h2} \cdot \epsilon_{elec\_consumption} \\ \phi_{co2} &= \phi_{fuel} \cdot \epsilon_{emission\_rate} \\ \phi_{co2\_captured} &= \phi_{fuel} \cdot \epsilon_{co2\_capture\_rate} \quad \text{(if CCS)} \\ \end{aligned}\]

Where:

$\phi$ represents the flow of each commodity
$\epsilon$ represents the stoichiometric coefficients defined in the Conversion Process Parameters section.

Input File (Standard Format)

The easiest way to include a thermal hydrogen plant asset in a model is to create a new file (either JSON or CSV) and place it in the assets directory together with the other assets.

your_case/
├── assets/
│   ├── thermalhydrogen.json    # or thermalhydrogen.csv
│   ├── other_assets.json
│   └── ...
├── system/
├── settings/
└── ...

This file can either be created manually, or using the template_asset function, as shown in the Adding an Asset to a System section of the User Guide. The file will be automatically loaded when you run your Macro model.

The following is an example of a thermal hydrogen plant asset input file:

{
    "NaturalGasH2SMR": [
        {
            "type": "ThermalHydrogen",
            "instance_data": [
                {
                    "id": "SE_Large_SMR_Non_CCS",
                    "location": "SE",
                    "fuel_commodity": "NaturalGas",
                    "co2_sink": "co2_sink",
                    "uc": true,
                    "h2_constraints": {
                        "MinFlowConstraint": true,
                        "MinUpTimeConstraint": true,
                        "MinDownTimeConstraint": true
                    },
                    "emission_rate": 0.181048235160161,
                    "fuel_consumption": 1.3009661455954666,
                    "electricity_consumption": 0.016404,
                    "investment_cost": 29902.10236,
                    "fixed_om_cost": 13685.61723,
                    "variable_om_cost": 2.250837989,
                    "capacity_size": 1082.95,
                    "startup_cost": 0.126968004,
                    "min_up_time": 3,
                    "min_down_time": 3,
                    "ramp_up_fraction": 0.5,
                    "ramp_down_fraction": 0.5,
                    "min_flow_fraction": 0.85,
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "SE_Large_SMR_Non_CCS"
                        }
                    }
                }
            ]
        }
    ]
}

Global Data vs Instance Data

When working with JSON input files, the global_data field can be used to group data that is common to all instances of the same asset type. This is useful for setting constraints that are common to all instances of the same asset type and avoid repeating the same data for each instance. See the Examples section below for an example.

The following tables outline the attributes that can be set for a thermal hydrogen plant asset.

Essential Attributes

Field	Type	Description
`Type`	String	Asset type identifier: "ThermalHydrogen" or "ThermalHydrogenCCS"
`id`	String	Unique identifier for the thermal hydrogen plant instance
`location`	String	Geographic location/node identifier
`fuel_commodity`	String	Commodity type of the fuel
`timedata`	String	Time resolution for time series data (default: "Hydrogen")
`uc`	Boolean	Whether the asset has unit commitment operations
`co2_sink`	String	CO₂ sink identifier
`fuel_start_vertex`	String	Fuel start vertex identifier. This is not required if the fuel commodity is present in the location.

Conversion Process Parameters

The following set of parameters control the conversion process and stoichiometry of the thermal hydrogen plant asset (see Flow Equations for more details).

Field	Type	Description	Units	Default
`fuel_consumption`	Float64	Fuel consumption per unit hydrogen	$MWh_{fuel}/MWh_{h2}$	1.0
`electricity_consumption`	Float64	Electricity consumption per unit hydrogen	$MWh_{elec}/MWh_{h2}$	0.0
`emission_rate`	Float64	CO₂ emission rate per unit fuel	$t_{CO₂}/MWh_{fuel}$	0.0
`capture_rate`	Float64	CO₂ capture rate per unit fuel	$t_{CO₂}/MWh_{fuel}$	1.0

Constraints Configuration

Thermal hydrogen plant assets can have different constraints applied to them, and the user can configure them using the following fields:

Field	Type	Description
`transform_constraints`	Dict{String,Bool}	List of constraints applied to the transformation component.
`h2_constraints`	Dict{String,Bool}	List of constraints applied to the hydrogen edge.
`fuel_constraints`	Dict{String,Bool}	List of constraints applied to the fuel edge.
`elec_constraints`	Dict{String,Bool}	List of constraints applied to the electricity edge.
`co2_constraints`	Dict{String,Bool}	List of constraints applied to the CO₂ edge.
`co2_captured_constraints`	Dict{String,Bool}	List of constraints applied to the CO₂ captured edge.

For example, if the user wants to apply the BalanceConstraint to the transformation component and the CapacityConstraint to the hydrogen edge, the constraints fields should be set as follows:

{
    "transform_constraints": {
        "BalanceConstraint": true
    },
    "h2_constraints": {
        "CapacityConstraint": true
    }
}

Users can refer to the Adding Asset Constraints to a System section of the User Guide for a list of all the constraints that can be applied to the different components of a thermal hydrogen plant asset.

Default constraints

To simplify the input file and the asset configuration, the following constraints are applied to the thermal hydrogen plant asset by default:

Balance constraint (applied to the transformation component)
Capacity constraint (applied to the hydrogen edge)
Ramping limits constraint (applied to the hydrogen edge)

Unit commitment constraints (when uc is set to true):

Minimum up and down time constraint (applied to the hydrogen edge)

Investment Parameters

Field	Type	Description	Units	Default
`can_retire`	Boolean	Whether thermal hydrogen plant capacity can be retired	-	true
`can_expand`	Boolean	Whether thermal hydrogen plant capacity can be expanded	-	true
`existing_capacity`	Float64	Initial installed thermal hydrogen plant capacity	MW	0.0
`capacity_size`	Float64	Unit size for capacity decisions	MW	1.0

Additional Investment Parameters

Maximum and minimum capacity constraints

If MaxCapacityConstraint or MinCapacityConstraint are added to the constraints dictionary for the hydrogen edge, the following parameters are used by Macro:

Field	Type	Description	Units	Default
`max_capacity`	Float64	Maximum allowed thermal hydrogen plant capacity	MW	Inf
`min_capacity`	Float64	Minimum allowed thermal hydrogen plant capacity	MW	0.0

Economic Parameters

Field	Type	Description	Units
`investment_cost`	Float64	CAPEX per unit thermal hydrogen plant capacity	$/MW/yr
`fixed_om_cost`	Float64	Fixed O&M costs of the thermal hydrogen plant	$/MW/yr
`variable_om_cost`	Float64	Variable O&M costs of the thermal hydrogen plant	$/MWh
`startup_cost`	Float64	Cost per MW of capacity to start the plant	$/MW per start

Operational Parameters

Field	Type	Description	Units	Default
`availability`	Dict	Path to availability file and column name	-	Empty

Additional Operational Parameters

Unit commitment parameters (when uc is set to true):

Field	Type	Description	Units	Default
`startup_fuel_consumption`	Float64	Fuel consumption per unit hydrogen to start the plant	$MWh_{fuel}/MWh_{h2}$	0.0

Minimum flow constraint

If MinFlowConstraint is added to the constraints dictionary for the hydrogen edge, the following parameter is used:

Field	Type	Description	Units	Default
`min_flow_fraction`	Float64	Minimum flow as fraction of capacity	fraction	0.0

Ramping limit constraint

If RampingLimitConstraint is added to the constraints dictionary for the hydrogen edge, the following parameters are used:

Field	Type	Description	Units	Default
`ramp_up_fraction`	Float64	Maximum increase in flow between timesteps	fraction	1.0
`ramp_down_fraction`	Float64	Maximum decrease in flow between timesteps	fraction	1.0

Minimum up and down time constraints

If MinUpTimeConstraint or MinDownTimeConstraint are added to the constraints dictionary for the hydrogen edge, the following parameters are used:

Field	Type	Description	Units	Default
`min_up_time`	Int64	Minimum time the plant must remain committed	hours	0
`min_down_time`	Int64	Minimum time the plant must remain shutdown	hours	0

Types - Asset Structure

The ThermalHydrogen and ThermalHydrogenCCS assets are defined as follows:

struct ThermalHydrogen{T} <: AbstractAsset
    id::AssetId
    thermalhydrogen_transform::Transformation
    h2_edge::Union{Edge{<:Hydrogen},EdgeWithUC{<:Hydrogen}}
    elec_edge::Edge{<:Electricity}
    fuel_edge::Edge{<:T}
    co2_edge::Edge{<:CO2}
end

struct ThermalHydrogenCCS{T} <: AbstractAsset
    id::AssetId
    thermalhydrogenccs_transform::Transformation
    h2_edge::Union{Edge{<:Hydrogen},EdgeWithUC{<:Hydrogen}}
    elec_edge::Edge{<:Electricity}
    fuel_edge::Edge{<:T}
    co2_edge::Edge{<:CO2}
    co2_captured_edge::Edge{<:CO2Captured}
end

where T is the type of the fuel commodity.

Constructors

Default constructor

ThermalHydrogen(id::AssetId, thermalhydrogen_transform::Transformation, h2_edge::Union{Edge{<:Hydrogen},EdgeWithUC{<:Hydrogen}}, elec_edge::Edge{<:Electricity}, fuel_edge::Edge{<:T}, co2_edge::Edge{<:CO2})

ThermalHydrogenCCS(id::AssetId, thermalhydrogenccs_transform::Transformation, h2_edge::Union{Edge{<:Hydrogen},EdgeWithUC{<:Hydrogen}}, elec_edge::Edge{<:Electricity}, fuel_edge::Edge{<:T}, co2_edge::Edge{<:CO2}, co2_captured_edge::Edge{<:CO2Captured})

Factory constructor

make(asset_type::Type{ThermalHydrogen}, data::AbstractDict{Symbol,Any}, system::System)
make(asset_type::Type{ThermalHydrogenCCS}, data::AbstractDict{Symbol,Any}, system::System)

Field	Type	Description
`asset_type`	`Type{ThermalHydrogen}` or `Type{ThermalHydrogenCCS}`	Macro type of the asset
`data`	`AbstractDict{Symbol,Any}`	Dictionary containing the input data for the asset
`system`	`System`	System to which the asset belongs

Examples

This section contains examples of how to use the thermal hydrogen plant asset in a Macro model.

Simple Thermal Hydrogen Plant with CCS

This example shows a thermal hydrogen plant with CCS capabilities, burning natural gas, and with unit commitment. A MinFlowConstraint constraint is applied to the hydrogen edge with a minimum flow fraction of 0.85. A MinUpTimeConstraint and MinDownTimeConstraint constraint is applied to the hydrogen edge with a minimum up and down time of 3 hours. A RampingLimitConstraint constraint is applied to the hydrogen edge with a ramping limit of 0.5. The asset has an availability time series loaded from a CSV file.

JSON Format:

{
    "NaturalGasH2SMR": [
        {
            "type": "ThermalHydrogenCCS",
            "instance_data": [
                {
                    "id": "SE_Large_SMR",
                    "location": "SE",
                    "fuel_commodity": "NaturalGas",
                    "co2_sink": "co2_sink",
                    "uc": true,
                    "h2_constraints": {
                        "MinFlowConstraint": true,
                        "MinUpTimeConstraint": true,
                        "MinDownTimeConstraint": true
                    },
                    "emission_rate": 0.006879832936086124,
                    "fuel_consumption": 1.300184721664035,
                    "electricity_consumption": 0.051727,
                    "capture_rate": 0.17416840222407487,
                    "investment_cost": 72729.17926,
                    "fixed_om_cost": 30021.9427,
                    "variable_om_cost": 6.942084285,
                    "capacity_size": 791.739,
                    "startup_cost": 0.253871541,
                    "min_up_time": 3,
                    "min_down_time": 3,
                    "ramp_up_fraction": 0.5,
                    "ramp_down_fraction": 0.5,
                    "min_flow_fraction": 0.85,
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "SE_Large_SMR"
                        }
                    }
                }
            ]
        }
    ]
}

CSV Format:

Type	id	location	timedata	uc	h2_constraints–MinFlowConstraint	h2_constraints–MinUpTimeConstraint	h2_constraints–MinDownTimeConstraint	emission_rate	fuel_consumption	electricity_consumption	capture_rate	investment_cost	fixed_om_cost	variable_om_cost	capacity_size	startup_cost	min_up_time	min_down_time	ramp_up_fraction	ramp_down_fraction	min_flow_fraction
ThermalHydrogenCCS	SE_Large_SMR	SE	Hydrogen	true	true	true	true	0.006879832936086124	1.300184721664035	0.051727	0.17416840222407487	72729.17926	30021.9427	6.942084285	791.739	0.253871541	3	3	0.5	0.5	0.85

Multiple Thermal Hydrogen withoutCCS Assets in Different Zones

This example shows three thermal hydrogen plant assets located in the SE, MIDAT, and NE regions. Each asset is burning natural gas, and has unit commitment enabled. A MinFlowConstraint constraint is applied to the hydrogen edge with a minimum flow fraction of 0.85. A MinUpTimeConstraint and MinDownTimeConstraint constraint is applied to the hydrogen edge with a minimum up and down time of 3 hours. A RampingLimitConstraint constraint is applied to the hydrogen edge with a ramping limit of 0.5. The asset has an availability time series loaded from a CSV file.

JSON Format:

Note that the global_data field is used to set the fields and constraints that are common to all instances of the same asset type.

{
    "NaturalGasH2SMR": [
        {
            "type": "ThermalHydrogen",
            "global_data": {
                "fuel_commodity": "NaturalGas",
                "co2_sink": "co2_sink",
                "uc": true,
                "h2_constraints": {
                    "MinFlowConstraint": true,
                    "MinUpTimeConstraint": true,
                    "MinDownTimeConstraint": true
                },
                "emission_rate": 0.181048235160161,
                "fuel_consumption": 1.3009661455954666,
                "electricity_consumption": 0.016404,
                "investment_cost": 29902.10236,
                "fixed_om_cost": 13685.61723,
                "variable_om_cost": 2.250837989,
                "capacity_size": 1082.95,
                "startup_cost": 0.126968004,
                "min_up_time": 3,
                "min_down_time": 3,
                "ramp_up_fraction": 0.5,
                "ramp_down_fraction": 0.5,
                "min_flow_fraction": 0.85
            },
            "instance_data": [
                {
                    "id": "SE_Large_SMR_Non_CCS",
                    "location": "SE",
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "SE_Large_SMR_Non_CCS"
                        }
                    }
                },
                {
                    "id": "MIDAT_Large_SMR_Non_CCS",
                    "location": "MIDAT",
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "MIDAT_Large_SMR_Non_CCS"
                        }
                    }
                },
                {
                    "id": "NE_Large_SMR_Non_CCS",
                    "location": "NE",
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "NE_Large_SMR_Non_CCS"
                        }
                    }
                }
            ]
        }
    ]
}

CSV Format:

Type	id	location	timedata	uc	h2_constraints–MinFlowConstraint	h2_constraints–MinUpTimeConstraint	h2_constraints–MinDownTimeConstraint	emission_rate	fuel_consumption	electricity_consumption	capture_rate	investment_cost	fixed_om_cost	variable_om_cost	capacity_size	startup_cost	min_up_time	min_down_time	ramp_up_fraction	ramp_down_fraction	min_flow_fraction
ThermalHydrogen	SE_Large_SMR_Non_CCS	SE	Hydrogen	true	true	true	true	0.181048235160161	1.3009661455954666	0.016404	0.0	29902.10236	13685.61723	2.250837989	1082.95	0.126968004	3	3	0.5	0.5	0.85

Best Practices

Use global data for common fields and constraints: Use the global_data field to set the fields and constraints that are common to all instances of the same asset type.
Set realistic stoichiometric coefficients: Ensure the transformation parameters reflect actual technology performance
Use meaningful IDs: Choose descriptive identifiers that indicate location and technology type
Consider unit commitment carefully: Enable unit commitment only when detailed operational modeling is needed
Set appropriate minimum up/down times: These should reflect the actual thermal characteristics of the plant
Validate costs: Ensure investment and O&M costs are in appropriate units and time periods
Test configurations: Start with simple configurations and gradually add complexity

Input File (Advanced Format)

Macro provides an advanced format for defining thermal hydrogen plant assets, offering users and modelers detailed control over asset specifications. This format builds upon the standard format and is ideal for those who need more comprehensive customization.

To understand the advanced format, consider the graph representation and the type definition of a thermal hydrogen plant asset. The input file mirrors this hierarchical structure.

A thermal hydrogen plant asset in Macro is composed of a transformation component, represented by a Transformation object, and five edges, each represented by an Edge object. The input file for a thermal hydrogen plant asset is therefore organized as follows:

{
    "transforms":{
        // ... transformation-specific attributes ...
    },
    "edges":{
        "fuel_edge": {
            // ... fuel_edge-specific attributes ...
        },
        "elec_edge": {
            // ... elec_edge-specific attributes ...
        },
        "h2_edge": {
            // ... h2_edge-specific attributes ...
        },
        "co2_edge": {
            // ... co2_edge-specific attributes ...
        },
        "co2_captured_edge": {
            // ... co2_captured_edge-specific attributes, only if CCS is present ...
        }
    }
}

Each top-level key (e.g., "transforms" or "edges") denotes a component type. The second-level keys either specify the attributes of the component (when there is a single instance) or identify the instances of the component (e.g., "fuel_edge", "h2_edge", etc.) when there are multiple instances. For multiple instances, a third-level key details the attributes for each instance.

Below is an example of an input file for a thermal hydrogen with CCS asset that sets up multiple thermal plants across different regions.

{
    "NaturalGasH2ATRCCS": [
        {
            "type": "ThermalHydrogenCCS",
            "global_data": {
                "nodes": {},
                "transforms": {
                    "timedata": "Hydrogen",
                    "constraints": {
                        "BalanceConstraint": true
                    }
                },
                "edges": {
                    "h2_edge": {
                        "commodity": "Hydrogen",
                        "unidirectional": true,
                        "has_capacity": true,
                        "can_retire": true,
                        "can_expand": true,
                        "integer_decisions": false,
                        "uc": true,
                        "constraints": {
                            "CapacityConstraint": true,
                            "RampingLimitConstraint": true,
                            "MinFlowConstraint": true,
                            "MinUpTimeConstraint": true,
                            "MinDownTimeConstraint": true
                        }
                    },
                    "fuel_edge": {
                        "commodity": "NaturalGas",
                        "unidirectional": true,
                        "has_capacity": false
                    },
                    "co2_edge": {
                        "commodity": "CO2",
                        "unidirectional": true,
                        "has_capacity": false,
                        "end_vertex": "co2_sink"
                    },
                    "co2_captured_edge": {
                        "commodity": "CO2Captured",
                        "unidirectional": true,
                        "has_capacity": false
                    },
                    "elec_edge": {
                        "commodity": "Electricity",
                        "unidirectional": true,
                        "has_capacity": false
                    }
                }
            },
            "instance_data": [
                {
                    "id": "SE_Large_SMR_wCCS_96pct",
                    "transforms": {
                        "emission_rate": 0.006879832936086124,
                        "fuel_consumption": 1.300184721664035,
                        "electricity_consumption": 0.051727,
                        "capture_rate": 0.17416840222407487
                    },
                    "edges": {
                        "h2_edge": {
                            "end_vertex": "h2_SE",
                            "availability": {
                                "timeseries": {
                                    "path": "system/availability.csv",
                                    "header": "SE_Large_SMR_wCCS_96pct"
                                }
                            },
                            "existing_capacity": 0.0,
                            "investment_cost": 72729.17926,
                            "fixed_om_cost": 30021.9427,
                            "variable_om_cost": 6.942084285,
                            "capacity_size": 791.739,
                            "startup_cost": 0.253871541,
                            "min_up_time": 3,
                            "min_down_time": 3,
                            "ramp_up_fraction": 0.5,
                            "ramp_down_fraction": 0.5,
                            "min_flow_fraction": 0.85
                        },
                        "fuel_edge": {
                            "start_vertex": "natgas_SE"
                        },
                        "elec_edge": {
                            "start_vertex": "elec_SE"
                        },
                        "co2_captured_edge": {
                            "end_vertex": "co2_captured_SE"
                        }
                    }
                },
                {
                    "id": "MIDAT_Large_SMR_wCCS_96pct",
                    "transforms": {
                        "emission_rate": 0.006879832936086124,
                        "fuel_consumption": 1.300184721664035,
                        "electricity_consumption": 0.051727,
                        "capture_rate": 0.17416840222407487
                    },
                    "edges": {
                        "h2_edge": {
                            "end_vertex": "h2_MIDAT",
                            "availability": {
                                "timeseries": {
                                    "path": "system/availability.csv",
                                    "header": "MIDAT_Large_SMR_wCCS_96pct"
                                }
                            },
                            "existing_capacity": 0.0,
                            "investment_cost": 72729.17926,
                            "fixed_om_cost": 30021.9427,
                            "variable_om_cost": 6.942084285,
                            "capacity_size": 791.739,
                            "startup_cost": 0.253871541,
                            "min_up_time": 3,
                            "min_down_time": 3,
                            "ramp_up_fraction": 0.5,
                            "ramp_down_fraction": 0.5,
                            "min_flow_fraction": 0.85
                        },
                        "fuel_edge": {
                            "start_vertex": "natgas_MIDAT"
                        },
                        "elec_edge": {
                            "start_vertex": "elec_MIDAT"
                        },
                        "co2_captured_edge": {
                            "end_vertex": "co2_captured_MIDAT"
                        }
                    }
                },
                {
                    "id": "NE_Large_SMR_wCCS_96pct",
                    "transforms": {
                        "emission_rate": 0.006879832936086124,
                        "fuel_consumption": 1.300184721664035,
                        "electricity_consumption": 0.051727,
                        "capture_rate": 0.17416840222407487
                    },
                    "edges": {
                        "h2_edge": {
                            "end_vertex": "h2_NE",
                            "availability": {
                                "timeseries": {
                                    "path": "system/availability.csv",
                                    "header": "NE_Large_SMR_wCCS_96pct"
                                }
                            },
                            "existing_capacity": 0.0,
                            "investment_cost": 72729.17926,
                            "fixed_om_cost": 30021.9427,
                            "variable_om_cost": 6.942084285,
                            "capacity_size": 791.739,
                            "startup_cost": 0.253871541,
                            "min_up_time": 3,
                            "min_down_time": 3,
                            "ramp_up_fraction": 0.5,
                            "ramp_down_fraction": 0.5,
                            "min_flow_fraction": 0.85
                        },
                        "fuel_edge": {
                            "start_vertex": "natgas_NE"
                        },
                        "elec_edge": {
                            "start_vertex": "elec_NE"
                        },
                        "co2_captured_edge": {
                            "end_vertex": "co2_captured_NE"
                        }
                    }
                }
            ]
        }
    ]
}

Key Points

The global_data field is utilized to define attributes and constraints that apply universally to all instances of a particular asset type.
The start_vertex and end_vertex fields indicate the nodes to which the edges are connected. These nodes must be defined in the nodes.json file.
By default, only the hydrogen edge is allowed to have capacity variables and constraints, as this represents the main capacity decision for the hydrogen production facility (see note below).
Unit commitment operations can be enabled for the hydrogen edge to model detailed operational constraints.
For a comprehensive list of attributes that can be configured for the transformation and edge components, refer to the transformation and edges pages of the Macro manual.

The `has_capacity` Edge Attribute

The has_capacity attribute is a flag that indicates whether a specific edge of an asset has a capacity variable, allowing it to be expanded or retired. Typically, users do not need to manually adjust this flag, as the asset creators in Macro have already configured it correctly for each edge. However, advanced users can use this flag to override the default settings for each edge if needed.

Prefixes

Users can apply prefixes to adjust parameters for the components of a thermal hydrogen plant asset, even when using the standard format. For instance, co2_can_retire will adjust the can_retire parameter for the CO2 edge, and co2_existing_capacity will adjust the existing_capacity parameter for the CO2 edge. Below are the prefixes available for modifying parameters for the components of a thermal hydrogen plant asset:

transform_ for the transformation component
h2_ for the hydrogen edge
co2_ for the CO2 edge
co2_captured_ for the CO2 captured edge
elec_ for the electricity edge
fuel_ for the fuel edge