Natural Gas DAC
Graph structure
A natural gas DAC is represented in Macro using the following graph structure:
A natural gas DAC asset is made of:
- 1
Transformationcomponent, representing the natural gas DAC process. - 5
Edgecomponents:- 1 incoming
NaturalGasEdge, representing the natural gas supply. - 1 incoming
CO2Edge, representing the CO2 that is absorbed by the natural gas DAC process. - 1 outgoing
ElectricityEdge, representing the electricity production. - 1 outgoing
CO2CapturedEdge, representing the CO2 that is captured. - 1 outgoing
CO2Edge, representing the CO2 that is emitted.
- 1 incoming
Attributes
The structure of the input file for a natural gas DAC asset follows the graph representation. Each global_data and instance_data will look like this:
{
"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 ...
}
}
}Transformation
The definition of the transformation object can be found here MacroEnergy.Transformation.
| Attribute | Type | Values | Default | Description/Units |
|---|---|---|---|---|
| timedata | String | String | Required | Time resolution for the time series data linked to the transformation. E.g. "NaturalGas". |
| constraints | Dict{String,Bool} | Any Macro constraint type for vertices | BalanceConstraint | List of constraints applied to the transformation. E.g. {"BalanceConstraint": true}. |
| capture_rate $\epsilon_{co2\_capture\_rate}$ | Float64 | Float64 | 1.0 | $t_{CO2}/MWh_{ng}$ |
| electricity_production $\epsilon_{elec\_prod}$ | Float64 | Float64 | 0.0 | $MWh_{elec}/MWh_{ng}$ |
| emission_rate $\epsilon_{emission\_rate}$ | Float64 | Float64 | 1.0 | $t_{CO2}/MWh_{ng}$ |
| fuel_consumption $\epsilon_{fuel\_consumption}$ | Float64 | Float64 | 0.0 | $MWh_{ng}/t_{CO2}$ |
The default constraint for the transformation part of the natural gas DAC asset is the following:
Flow equations
In the following equations, $\phi$ is the flow of the commodity and $\epsilon$ is the stoichiometric coefficient defined in the transformation table below.
\[\begin{aligned} \phi_{elec} &= \phi_{co2} \cdot \epsilon_{elec\_prod} \\ \phi_{ng} &= -\phi_{co2} \cdot \epsilon_{fuel\_consumption} \\ \phi_{co2} &= \phi_{ng} \cdot \epsilon_{emission\_rate} \\ \phi_{co2\_captured} + \phi_{co2} &= \phi_{ng} \cdot \epsilon_{co2\_capture\_rate} \\ \end{aligned}\]
Edges
As a modeling decision, only the incoming CO2 edge is allowed to expand. Therefore, the has_capacity attribute can only be set for this edge. For all the other edges, this attribute is pre-set to false to ensure the correct modeling of the asset.
The unidirectional attribute is only available for the incoming CO2 edge. For the other edges, this attribute is pre-set to true to ensure the correct modeling of the asset.
The definition of the Edge object can be found here MacroEnergy.Edge.
| Attribute | Type | Values | Default | Description |
|---|---|---|---|---|
| type | String | Any Macro commodity type matching the commodity of the edge | Required | Commodity of the edge. E.g. "Electricity". |
| start_vertex | String | Any node id present in the system matching the commodity of the edge | Required | ID of the starting vertex of the edge. The node must be present in the nodes.json file. E.g. "natgas_node_1". |
| end_vertex | String | Any node id present in the system matching the commodity of the edge | Required | ID of the ending vertex of the edge. The node must be present in the nodes.json file. E.g. "elec_node_1". |
| constraints | Dict{String,Bool} | Any Macro constraint type for Edges | Empty | List of constraints applied to the edge. E.g. {"CapacityConstraint": true}. |
| availability | Dict | Availability file path and header | Empty | Path to the availability file and column name for the availability time series to link to the edge. E.g. {"timeseries": {"path": "assets/availability.csv", "header": "Availability_MW_z1"}}. |
| can_expand | Bool | Bool | false | Whether the edge is eligible for capacity expansion. |
| can_retire | Bool | Bool | false | Whether the edge is eligible for capacity retirement. |
| capacity_size | Float64 | Float64 | 1.0 | Size of the edge capacity. |
| existing_capacity | Float64 | Float64 | 0.0 | Existing capacity of the edge in MW. |
| fixed_om_cost | Float64 | Float64 | 0.0 | Fixed operations and maintenance cost (USD/MW-year). |
| has_capacity | Bool | Bool | false | Whether capacity variables are created for the edge. |
| integer_decisions | Bool | Bool | false | Whether capacity variables are integers. |
| investment_cost | Float64 | Float64 | 0.0 | Annualized capacity investment cost (USD/MW-year) |
| max_capacity | Float64 | Float64 | Inf | Maximum allowed capacity of the edge (MW). Note: add the MaxCapacityConstraint to the constraints dictionary to activate this constraint. |
| min_capacity | Float64 | Float64 | 0.0 | Minimum allowed capacity of the edge (MW). Note: add the MinCapacityConstraint to the constraints dictionary to activate this constraint. |
| min_flow_fraction | Float64 | Number $\in$ [0,1] | 0.0 | Minimum flow of the edge as a fraction of the total capacity. Note: add the MinFlowConstraint to the constraints dictionary to activate this constraint. |
| ramp_down_fraction | Float64 | Number $\in$ [0,1] | 1.0 | Maximum decrease in flow between two time steps, reported as a fraction of the capacity. Note: add the RampingLimitConstraint to the constraints dictionary to activate this constraint. |
| ramp_up_fraction | Float64 | Number $\in$ [0,1] | 1.0 | Maximum increase in flow between two time steps, reported as a fraction of the capacity. Note: add the RampingLimitConstraint to the constraints dictionary to activate this constraint. |
| unidirectional | Bool | Bool | false | Whether the edge is unidirectional. |
| variable_om_cost | Float64 | Float64 | 0.0 | Variable operation and maintenance cost (USD/MWh). |
The only default constraint for the edges of the natural gas DAC asset is the Capacity constraint applied to the incoming CO2 edge.
Example
The following input file example shows how to create a natural gas DAC asset in each of the three zones NE, SE and MIDAT.
{
"NaturalGasDAC": [
{
"type": "NaturalGasDAC",
"global_data": {
"transforms": {
"timedata": "NaturalGas",
"constraints": {
"BalanceConstraint": true
}
},
"edges": {
"co2_edge": {
"type": "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": {
"type": "CO2",
"unidirectional": true,
"has_capacity": false,
"end_vertex": "co2_sink"
},
"ng_edge": {
"type": "NaturalGas",
"unidirectional": true,
"has_capacity": false
},
"elec_edge": {
"type": "Electricity",
"unidirectional": true,
"has_capacity": false
},
"co2_captured_edge": {
"type": "CO2Captured",
"unidirectional": true,
"has_capacity": false,
"end_vertex": "co2_captured_sink"
}
}
},
"instance_data": [
{
"id": "SE_Sorbent_DAC",
"transforms": {
"emission_rate": 0.005516648,
"capture_rate": 0.546148172,
"electricity_production": 0.125,
"fuel_consumption": 3.047059915
},
"edges": {
"co2_edge": {
"availability": {
"timeseries": {
"path": "assets/availability.csv",
"header": "SE_Sorbent_DAC"
}
},
"existing_capacity": 0.0,
"investment_cost": 869000.00,
"fixed_om_cost": 384000.00,
"variable_om_cost": 58.41,
"ramp_up_fraction": 1.0,
"ramp_down_fraction": 1.0
},
"ng_edge": {
"start_vertex": "natgas_SE"
},
"elec_edge": {
"end_vertex": "elec_SE"
}
}
},
{
"id": "MIDAT_Sorbent_DAC",
"transforms": {
"emission_rate": 0.005516648,
"capture_rate": 0.546148172,
"electricity_production": 0.125,
"fuel_consumption": 3.047059915
},
"edges": {
"co2_edge": {
"availability": {
"timeseries": {
"path": "assets/availability.csv",
"header": "MIDAT_Sorbent_DAC"
}
},
"existing_capacity": 0.0,
"investment_cost": 869000.00,
"fixed_om_cost": 384000.00,
"variable_om_cost": 58.41,
"ramp_up_fraction": 1.0,
"ramp_down_fraction": 1.0
},
"ng_edge": {
"start_vertex": "natgas_MIDAT"
},
"elec_edge": {
"end_vertex": "elec_MIDAT"
}
}
},
{
"id": "NE_Sorbent_DAC",
"transforms": {
"emission_rate": 0.005516648,
"capture_rate": 0.546148172,
"electricity_production": 0.125,
"fuel_consumption": 3.047059915
},
"edges": {
"co2_edge": {
"availability": {
"timeseries": {
"path": "assets/availability.csv",
"header": "NE_Sorbent_DAC"
}
},
"existing_capacity": 0.0,
"investment_cost": 869000.00,
"fixed_om_cost": 384000.00,
"variable_om_cost": 58.41,
"ramp_up_fraction": 1.0,
"ramp_down_fraction": 1.0
},
"ng_edge": {
"start_vertex": "natgas_NE"
},
"elec_edge": {
"end_vertex": "elec_NE"
}
}
}
]
}
]
}