Natural Gas DAC

Contents

Overview | Asset Structure | Input File (Standard Format) | Types - Asset Structure | Constructors | Examples | Best Practices | Input File (Advanced Format)

Overview

Natural Gas DAC (Direct Air Capture) assets in Macro represent carbon dioxide removal technologies that use natural gas as a fuel source to capture CO₂ directly from the atmosphere. These assets are defined using either JSON or CSV input files placed in the assets directory, typically named natgasdac.json or natgasdac.csv.

Asset Structure

A natural gas DAC asset consists of one transformation component and five edge components:

1. Transformation Component: Balances the incoming and outgoing flows of natural gas, CO₂, and electricity
2. Natural Gas Edge: Incoming edge representing natural gas fuel supply
3. CO₂ Edge: Incoming edge representing CO₂ absorption from atmosphere
4. Electricity Edge: Outgoing edge representing electricity production
5. CO₂ Emission Edge: Outgoing edge representing CO₂ emissions from the process
6. CO₂ Captured Edge: Outgoing edge representing captured CO₂

Here is a graphical representation of the Natural Gas DAC asset:

Flow Equations

The natural gas DAC asset follows these stoichiometric relationships:

\[\begin{aligned} \phi_{elec} &= \phi_{co2} \cdot \epsilon_{elec\_prod} \\ \phi_{ng} &= \phi_{co2} \cdot \epsilon_{fuel\_consumption} \\ \phi_{co2} &= \phi_{ng} \cdot \epsilon_{emission\_rate} \\ \phi_{co2\_captured} &= \phi_{ng} \cdot \epsilon_{co2\_capture\_rate} + \phi_{co2}\\ \end{aligned}\]

Where:

• $\phi$ represents the flow of each commodity
• $\epsilon$ represents the stoichiometric coefficients defined in the table below (see table Conversion Process Parameters)

Input File (Standard Format)

The easiest way to include a natural gas DAC 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/
│   ├── natgasdac.json    # or natgasdac.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 Natural Gas DAC asset input file:

{
    "NaturalGasDAC": [
        {
            "type": "NaturalGasDAC",
            "instance_data": [
                {
                    "id": "SE_Solvent_DAC",
                    "location": "SE",
                    "co2_sink": "co2_sink",
                    "emission_rate": 0.001810482,
                    "capture_rate": 0.179237753,
                    "electricity_production": 0.125,
                    "fuel_consumption": 3.047059187,
                    "investment_cost": 973000,
                    "fixed_om_cost": 430000,
                    "variable_om_cost": 65.42,
                    "co2_constraints": {
                        "RampingLimitConstraint": true
                    },
                    "ramp_up_fraction": 1.0,
                    "ramp_down_fraction": 1.0,
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "SE_Solvent_DAC"
                        }
                    }
                }
            ]
        }
    ]
}

The following tables outline the attributes that can be set for a Natural Gas DAC asset.

Essential Attributes

Conversion Process Parameters

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

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 a Natural Gas DAC asset.

Constraints Configuration

Natural gas DAC assets can have different constraints applied to them, and the user can configure them using the following fields:

Default constraints

To simplify the input file and the asset configuration, the following constraints are applied to the Natural Gas DAC asset by default:

• Balance constraint (applied to the transformation component)
• Capacity constraint (applied to the CO₂ edge)

Investment Parameters

Additional Investment Parameters

Maximum and minimum capacity constraints

If MaxCapacityConstraint or MinCapacityConstraint are added to the constraints dictionary for the CO₂ edge, the following parameters are used by Macro:

Economic Parameters

Operational Parameters

Additional Operational Parameters

Ramping limit constraint

If RampingLimitConstraint is added to the constraints dictionary for the CO₂ edge, the following parameters are used:

Types - Asset Structure

The NaturalGasDAC asset is defined as follows:

struct NaturalGasDAC <: AbstractAsset
    id::AssetId
    natgasdac_transform::Transformation
    co2_edge::Edge{<:CO2}
    co2_emission_edge::Edge{<:CO2}
    natgas_edge::Edge{<:NaturalGas}
    elec_edge::Edge{<:Electricity}
    co2_captured_edge::Edge{<:CO2Captured}
end

Constructors

Default constructor

NaturalGasDAC(id::AssetId, natgasdac_transform::Transformation, co2_edge::Edge{<:CO2}, co2_emission_edge::Edge{<:CO2}, natgas_edge::Edge{<:NaturalGas}, elec_edge::Edge{<:Electricity}, co2_captured_edge::Edge{<:CO2Captured})

Factory constructor

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

Examples

This section contains examples of how to use the natural gas DAC asset in a Macro model.

Fixed Capacity Natural Gas DAC

This example shows a natural gas DAC asset located in the SE region. A RampingLimitConstraint constraint is applied to the CO₂ edge with a ramping limit of 1.0. The asset has an availability time series loaded from a CSV file.

JSON Format:

{
    "NaturalGasDAC": [
        {
            "type": "NaturalGasDAC",
            "instance_data": [
                {
                    "id": "SE_Solvent_DAC",
                    "location": "SE",
                    "co2_sink": "co2_sink",
                    "co2_constraints": {
                        "RampingLimitConstraint": true
                    },
                    "emission_rate": 0.001810482,
                    "capture_rate": 0.179237753,
                    "electricity_production": 0.125,
                    "fuel_consumption": 3.047059187,
                    "investment_cost": 973000,
                    "fixed_om_cost": 430000,
                    "variable_om_cost": 65.42,
                    "ramp_up_fraction": 1.0,
                    "ramp_down_fraction": 1.0,
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "SE_Solvent_DAC"
                        }
                    }
                }
            ]
        }
    ]
}

CSV Format:

Multiple Natural Gas DAC assets in different zones

This example shows three natural gas DAC assets located in the SE, MIDAT, and NE regions. A RampingLimitConstraint constraint is applied to the CO₂ edge with a ramping limit of 1.0. 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.

{
    "NaturalGasDAC": [
        {
            "type": "NaturalGasDAC",
            "global_data": {
                "transforms_timedata": "NaturalGas",
                "co2_constraints": {
                    "RampingLimitConstraint": true
                },
                "co2_sink": "co2_sink",
                "emission_rate": 0.001810482,
                "capture_rate": 0.179237753,
                "electricity_production": 0.125,
                "fuel_consumption": 3.047059187,
                "investment_cost": 973000,
                "fixed_om_cost": 430000,
                "variable_om_cost": 65.42,
                "ramp_up_fraction": 1.0,
                "ramp_down_fraction": 1.0
            },
            "instance_data": [
                {
                    "id": "SE_Solvent_DAC",
                    "location": "SE",
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "SE_Solvent_DAC"
                        }
                    }
                },
                {
                    "id": "MIDAT_Solvent_DAC",
                    "location": "MIDAT",
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "MIDAT_Solvent_DAC"
                        }
                    }
                },
                {
                    "id": "NE_Solvent_DAC",
                    "location": "NE",
                    "availability": {
                        "timeseries": {
                            "path": "system/availability.csv",
                            "header": "NE_Solvent_DAC"
                        }
                    }
                }
            ]
        }
    ]
}

CSV Format:

Best Practices

1. 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.
2. Set realistic stoichiometric coefficients: Ensure the transformation parameters reflect actual technology performance
3. Use meaningful IDs: Choose descriptive identifiers that indicate location and technology type
4. Consider ramping constraints: Set appropriate ramping limits based on technology characteristics
5. Use constraints selectively: Only enable constraints that are necessary for your modeling needs
6. Validate costs: Ensure investment and O&M costs are in appropriate units
7. Test configurations: Start with simple configurations and gradually add complexity
8. Account for emissions: Include both direct emissions and electricity production in the model

Input File (Advanced Format)

Macro provides an advanced format for defining Natural Gas DAC 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 Natural Gas DAC asset. The input file mirrors this hierarchical structure.

A Natural Gas DAC asset in Macro is composed of a transformation component, represented by a Transformation object, and two edges (CO₂ and electricity), each represented by an Edge object. The input file for a Natural Gas DAC asset is therefore organized as follows:

{
    "transforms": {
        // ... transformation-specific attributes ...
    },
    "edges":{
        "ng_edge": {
            // ... ng_edge-specific attributes ...
        },
        "co2_edge": {
            // ... co2_edge-specific attributes ...
        },
        "elec_edge": {
            // ... elec_edge-specific attributes ...
        },
        "co2_emission_edge": {
            // ... co2_emission_edge-specific attributes ...
        },
        "co2_captured_edge": {
            // ... co2_captured_edge-specific attributes ...
        }
    }
}

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., "co2edge" or "elecedge") when there are multiple instances. For multiple instances, a third-level key details the attributes for each instance.

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., "co2_edge", "co2_emission_edge", "natgas_edge", "elec_edge", "co2_captured_edge") 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 natural gas DAC asset that sets up multiple natural gas DAC assets across different regions.

{
    "NaturalGasDAC": [
        {
            "type": "NaturalGasDAC",
            "global_data": {
                "transforms": {
                    "timedata": "NaturalGas",
                    "constraints": {
                        "BalanceConstraint": true
                    }
                },
                "edges": {
                    "co2_edge": {
                        "commodity": "CO2",
                        "unidirectional": true,
                        "has_capacity": true,
                        "start_vertex": "co2_sink",
                        "can_retire": true,
                        "can_expand": true,
                        "integer_decisions": false,
                        "uc": false,
                        "constraints": {
                            "CapacityConstraint": true,
                            "RampingLimitConstraint": true
                        }
                    },
                    "co2_emission_edge": {
                        "commodity": "CO2",
                        "unidirectional": true,
                        "has_capacity": false,
                        "end_vertex": "co2_sink"
                    },
                    "natgas_edge": {
                        "commodity": "NaturalGas",
                        "unidirectional": true,
                        "has_capacity": false
                    },
                    "elec_edge": {
                        "commodity": "Electricity",
                        "unidirectional": true,
                        "has_capacity": false
                    },
                    "co2_captured_edge": {
                        "commodity": "CO2Captured",
                        "unidirectional": true,
                        "has_capacity": false
                    }
                }
            },
            "instance_data": [
                {
                    "id": "SE_Solvent_DAC",
                    "transforms": {
                        "emission_rate": 0.001810482,
                        "capture_rate": 0.179237753,
                        "electricity_production": 0.125,
                        "fuel_consumption": 3.047059187
                    },
                    "edges": {
                        "co2_edge": {
                            "availability": {
                                "timeseries": {
                                    "path": "system/availability.csv",
                                    "header": "SE_Solvent_DAC"
                                }
                            },
                            "existing_capacity": 0.0,
                            "investment_cost": 973000,
                            "fixed_om_cost": 430000,
                            "variable_om_cost": 65.42,
                            "ramp_up_fraction": 1.0,
                            "ramp_down_fraction": 1.0
                        },
                        "natgas_edge": {
                            "start_vertex": "natgas_SE"
                        },
                        "elec_edge": {
                            "end_vertex": "elec_SE"
                        },
                        "co2_captured_edge": {
                            "end_vertex": "co2_captured_SE"
                        }
                    }
                },
                {
                    "id": "MIDAT_Solvent_DAC",
                    "transforms": {
                        "emission_rate": 0.001810482,
                        "capture_rate": 0.179237753,
                        "electricity_production": 0.125,
                        "fuel_consumption": 3.047059187
                    },
                    "edges": {
                        "co2_edge": {
                            "availability": {
                                "timeseries": {
                                    "path": "system/availability.csv",
                                    "header": "MIDAT_Solvent_DAC"
                                }
                            },
                            "existing_capacity": 0.0,
                            "investment_cost": 973000,
                            "fixed_om_cost": 430000,
                            "variable_om_cost": 65.42,
                            "ramp_up_fraction": 1.0,
                            "ramp_down_fraction": 1.0
                        },
                        "natgas_edge": {
                            "start_vertex": "natgas_MIDAT"
                        },
                        "elec_edge": {
                            "end_vertex": "elec_MIDAT"
                        },
                        "co2_captured_edge": {
                            "end_vertex": "co2_captured_MIDAT"
                        }
                    }
                },
                {
                    "id": "NE_Solvent_DAC",
                    "transforms": {
                        "emission_rate": 0.001810482,
                        "capture_rate": 0.179237753,
                        "electricity_production": 0.125,
                        "fuel_consumption": 3.047059187
                    },
                    "edges": {
                        "co2_edge": {
                            "availability": {
                                "timeseries": {
                                    "path": "system/availability.csv",
                                    "header": "NE_Solvent_DAC"
                                }
                            },
                            "existing_capacity": 0.0,
                            "investment_cost": 973000,
                            "fixed_om_cost": 430000,
                            "variable_om_cost": 65.42,
                            "ramp_up_fraction": 1.0,
                            "ramp_down_fraction": 1.0
                        },
                        "natgas_edge": {
                            "start_vertex": "natgas_NE"
                        },
                        "elec_edge": {
                            "end_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 CO₂ edge is allowed to have capacity variables and constraints, as this represents the main capacity decision for the DAC facility (see note below).
• 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.