* Switch to new major release, ``>=v0.2.1`` of ``atlite``. The version upgrade comes along with significant speed up for the rule ``build_renewable_profiles.py`` (~factor 2). A lot of the code which calculated the landuse availability is now outsourced and does not rely on ``glaes``, ``geokit`` anymore. This facilitates the environment building and version compatibility of ``gdal``, ``libgdal`` with other packages.
* The minimum python version was set to ``3.8``.
* The rule and script ``build_country_flh`` are removed as they're no longer used or maintained.
* The flag ``keep_all_available_areas`` in the configuration for renewable potentials (config.yaml -> renewable -> {technology}) was deprecated and now defaults to ``True``.
* The tutorial cutout was renamed from ``cutouts/europe-2013-era5.nc`` to ``cutouts/europe-2013-era5-tutorial.nc`` to accomodate tutorial and productive cutouts side-by-side.
* Fix: Value for ``co2base`` in ``config.yaml`` adjusted to 1.487e9 t CO2-eq (from 3.1e9 t CO2-eq). The new value represents emissions related to the electricity sector for EU+UK. The old value was ~2x too high and used when the emissions wildcard in ``{opts}`` was used.
* Add option to pre-aggregate nodes without power injections (positive or negative, i.e. generation or demand) to electrically closest nodes or neighbors in ``simplify_network``. Defaults to ``False``. This affects nodes that are no substations or have no offshore connection.
* Fix: Add escape in :mod:`base_network` if all TYNDP links are already contained in the network [`#246 <https://github.com/PyPSA/pypsa-eur/pull/246>`_].
* Bugfix in :mod:`solve_operations_network`: optimised capacities are now fixed for all extendable links, not only HVDC links [`#244 <https://github.com/PyPSA/pypsa-eur/pull/244>`_].
* The ``focus_weights`` are now also considered when pre-clustering in the :mod:`simplify_network` rule [`#241 <https://github.com/PyPSA/pypsa-eur/pull/241>`_].
* Bugfix in :mod:`build_renewable_profile` where offshore wind profiles could no longer be created [`#249 <https://github.com/PyPSA/pypsa-eur/pull/249>`_].
* Bugfix: Lower expansion limit of extendable carriers is now set to the existing capacity, i.e. ``p_nom_min = p_nom`` (0 before). Simultaneously, the upper limit (``p_nom_max``) is now the maximum of the installed capacity (``p_nom``) and the previous estimate based on land availability (``p_nom_max``) [`#260 <https://github.com/PyPSA/pypsa-eur/pull/260>`_].
* Added an option to alter the capital cost (``c``) or installable potentials (``p``) of carriers by a factor via ``carrier+{c,p}factor`` in the ``{opts}`` wildcard.
This can be useful for exploring uncertain cost parameters.
Example: ``solar+c0.5`` reduces the capital cost of solar to 50% of original values
* Add renewable power plants from `OPSD <https://data.open-power-system-data.org/renewable_power_plants/2020-08-25>`_ to the network for specified technologies.
This will overwrite the capacities calculated from the heuristic approach in :func:`estimate_renewable_capacities()`
* Electricity consumption data is now retrieved directly from the `OPSD website <https://data.open-power-system-data.org/time_series/2019-06-05>`_ using the rule :mod:`build_load_data`.
The user can decide whether to take the ENTSO-E power statistics data (default) or the ENTSO-E transparency data
* Fixed a bug for storage units such that individual store and dispatch efficiencies are correctly taken account of rather than only their round-trip efficiencies.
* The optimization is now performed using the ``pyomo=False`` setting in the :func:`pypsa.lopf.network_lopf`. This speeds up the solving process significantly and consumes much less memory. The inclusion of additional constraints were adjusted to the new implementation. They are all passed to the :func:`network_lopf` function via the ``extra_functionality`` argument. The rule ``trace_solve_network`` was integrated into the rule :mod:`solve_network` and can be activated via configuration with ``solving: options: track_iterations: true``. The charging and discharging capacities of batteries modelled as store-link combination are now coupled [`#116 <https://github.com/PyPSA/pypsa-eur/pull/116>`_].
* An updated extract of the `ENTSO-E Transmission System Map <https://www.entsoe.eu/data/map/>`_ (including Malta) was added to the repository using the `GridKit <https://github.com/PyPSA/GridKit>`_ tool. This tool has been updated to retrieve up-to-date map extracts using a single `script <https://github.com/PyPSA/GridKit/blob/master/entsoe/runall_in_docker.sh>`_. The update extract features 5322 buses, 6574 lines, 46 links. [`#118 <https://github.com/PyPSA/pypsa-eur/pull/118>`_].
* Added a 30 minute `video introduction <https://pypsa-eur.readthedocs.io/en/latest/introduction.html>`_ and a 20 minute `video tutorial <https://pypsa-eur.readthedocs.io/en/latest/tutorial.html>`_
* Networks now store a color and a nicely formatted name for each carrier, accessible via ``n.carrier['color']`` and ``n.carrier['nice_name'] ``(networks after ``elec.nc``).
* Added an option to skip iterative solving usually performed to update the line impedances of expanded lines at ``solving: options: skip_iterations:``.
*``snakemake`` rules for retrieving cutouts and the natura raster can now be disabled independently from their respective rules to build them; via ``config.*yaml`` [`#136 <https://github.com/PyPSA/pypsa-eur/pull/136>`_].
* Removed the ``id`` column for custom power plants in ``data/custom_powerplants.csv`` to avoid custom power plants with conflicting ids getting attached to the wrong bus [`#131 <https://github.com/PyPSA/pypsa-eur/pull/131>`_].
* Add option ``renewables: {carrier}: keep_all_available_areas:`` to use all availabe weather cells for renewable profile and potential generation. The default ignores weather cells where only less than 1 MW can be installed [`#150 <https://github.com/PyPSA/pypsa-eur/pull/150>`_].
* Added a function ``_helpers.load_network()`` which loads a network with overridden components specified in ``snakemake.config['override_components']`` [`#128 <https://github.com/PyPSA/pypsa-eur/pull/128>`_].
* Bugfix in :mod:`cluster_network` which now skips recalculation of link parameters if there are no links [`#149 <https://github.com/PyPSA/pypsa-eur/pull/149>`_].
* Documentation on installation, workflows and configuration settings is now available online at `pypsa-eur.readthedocs.io <pypsa-eur.readthedocs.io>`_ [`#65 <https://github.com/PyPSA/pypsa-eur/pull/65>`_].
* The power plant database was updated with extensive filtering options via ``pandas.query`` functionality [`#84 <https://github.com/PyPSA/pypsa-eur/pull/84>`_ and `#94 <https://github.com/PyPSA/pypsa-eur/pull/94>`_].
* Continuous integration testing with `Travis CI <https://travis-ci.org>`_ is now included for Linux, Mac and Windows [`#82 <https://github.com/PyPSA/pypsa-eur/pull/82>`_].
* Emission prices can be added to marginal costs of generators through the keyworks ``Ep`` in the ``{opts}`` wildcard [`#100 <https://github.com/PyPSA/pypsa-eur/pull/100>`_].
* Focus weights can now be specified for particular countries for the network clustering, which allows to set a proportion of the total number of clusters for particular countries [`#87 <https://github.com/PyPSA/pypsa-eur/pull/87>`_].
* A new rule :mod:`add_extra_components` allows to add additional components to the network only after clustering. It is thereby possible to model storage units (e.g. battery and hydrogen) in more detail via a combination of ``Store``, ``Link`` and ``Bus`` elements [`#97 <https://github.com/PyPSA/pypsa-eur/pull/97>`_].
* Hydrogen pipelines (including cost assumptions) can now be added alongside clustered network connections in the rule :mod:`add_extra_components` . Set ``electricity: extendable_carriers: Link: [H2 pipeline]`` and ensure hydrogen storage is modelled as a ``Store``. This is a first simplified stage [`#108 <https://github.com/PyPSA/pypsa-eur/pull/108>`_].
* The new function ``_helpers.mock_snakemake`` creates a ``snakemake`` object which mimics the actual ``snakemake`` object produced by workflow by parsing the ``Snakefile`` and setting all paths for inputs, outputs, and logs. This allows running all scripts within a (I)python terminal (or just by calling ``python <script-name>``) and thereby facilitates developing and debugging scripts significantly [`#107 <https://github.com/PyPSA/pypsa-eur/pull/107>`_].
* Upload pre-built networks to `zenodo data repository <https://doi.org/10.5281/zenodo.3601881>`_ with `CC BY 4.0 <https://creativecommons.org/licenses/by/4.0/>`_ license.
