Carrier
Carriers define the properties of energy types used throughout the power system model (electricity, gas, heat, coal, wind, solar, etc.). Unlike other components, carriers are simpler entities with direct properties rather than input/output attributes.
Properties
Carriers have the following properties:
| Property | Data Type | Unit | Default | Required | Description |
|---|---|---|---|---|---|
name | TEXT | n/a | - | Yes | Unique carrier name (e.g., "AC", "gas", "wind", "solar") |
nice_name | TEXT | n/a | - | No | Display-friendly name for UI and reports |
color | TEXT | n/a | - | No | Hex color code for visualization (e.g., "#2ca02c" for green) |
co2_emissions | REAL | tonnes/MWh | 0.0 | No | CO₂ emissions factor per MWh of primary energy |
max_growth | REAL | MW | NULL | No | Maximum new installed capacity per investment period |
max_relative_growth | REAL | per unit | 0.0 | No | Maximum growth as fraction of existing capacity |
curtailable | BOOLEAN | n/a | FALSE | No | Whether the carrier can be curtailed. This parameter influences whether curtailment will be tracked for technologies with this carrier. |
CO₂ Emissions
The co2_emissions property enables system-wide carbon accounting and constraints. We recommend using model-specific values, but we tabulate some typical values below for reference.
| Carrier | CO₂ Emissions (tonnes/MWh) |
|---|---|
| Coal | 0.35 |
| Natural Gas | 0.20 |
| Oil | 0.26 |
| Nuclear | 0.01 |
| Wind/Solar/Hydro | 0.00 |
These factors are used in emissions limit constraints and carbon pricing scenarios.
Growth Constraints
Control carrier deployment rates in capacity expansion models:
max_growth: Absolute limit (e.g., "Maximum 500 MW new solar per year")max_relative_growth: Relative limit (e.g., "Solar can grow by maximum 20% per year")- Both constraints can be active simultaneously
These reflect real-world manufacturing, supply chain, and policy constraints.
Usage in Components
Carriers are referenced by components through the carrier_id foreign key:
- Buses: Must use AC, DC, heat, or gas carriers
- Generators: Specify fuel type (coal, gas, wind, solar, etc.)
- Loads: Define what type of energy is consumed
- Lines: Must use AC carrier
- Links: Can convert between different carriers
- Storage Units: Specify what carrier is stored
This enables multi-carrier energy system modeling with sector coupling.