Another great resource for `cost assumptions <https://ens.dk/en/our-services/projections-and-models/technology-data`_ is the cost database from the Danish Energy Agency.
Some cost assumptions (e.g. marginal cost and capital cost) can be directly overwritten in the ``config.yaml`` (cf. Section :ref:`costs_cf` in :ref:`config`).
To change cost assumptions in more detail, modify cost assumptions directly in ``data/costs.csv`` as this is not yet supported through the config file.
You can also build multiple different cost databases. Make a renamed copy of ``data/costs.csv`` (e.g. ``data/costs-optimistic.csv``) and set the variable ``COSTS=data/costs-optimistic.csv`` in the ``Snakefile``.