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Extending MIMOSA

General form of the model

MIMOSA is built with Pyomo, an open-source optimisation modelling package. The model combines variables and parameters with equations that calculate model outcomes and constraints that restrict the feasible solution. The selected objective module either maximises discounted welfare or minimises discounted global costs.

The following pages explain how to add variables, equations, constraints, parameters and complete model components. They focus on the conventions used in MIMOSA rather than providing a general introduction to Pyomo.

MIMOSA's shared Pyomo AbstractModel, time and region sets, and baseline inputs are created in mimosa/base_model.py. The components listed in mimosa/abstract_model.py then add their variables, parameters, equations and constraints to this shared object, which is always called m:

m = create_base_model()

A note about file structure

After forking and cloning MIMOSA to your computer, you will find a file structure that looks like this:

MIMOSA file structure
mimosa/
├── abstract_model.py # (1)!
├── base_model.py # (2)!
├── mimosa.py
├── components/ # (3)!
│   ├── emissions.py
│   ├── mitigation.py
│   └── ...
└── inputdata/
    ├── config/
    │   └── config_default.yaml # (4)!
    ├── regionalparams/
    └── data/

run.py # (5)!
  1. The model components are listed and combined in this file.
  2. Shared time, region and baseline input parameters are defined in this file.
  3. The components discussed in the Model documentation are defined in this folder.
  4. Configuration parameter types and default values are defined in this file.
  5. Example of a basic model run. Place your run files here, such that the mimosa package from this folder is used, and not a version previously installed through pip install mimosa.

For most extensions, use the following steps:

  1. Create a new component (optional, only necessary if the extension is a new module)
  2. Add new variables and constraints to the model
  3. Add new parameters and data to the model

For more advanced extensions, see Selectable modules and Model options.