Fix marginal modelling issue when shares are NaNs

v.1.6.8

Black reformating

v.1.6.7: Remove heat input from PEM electrolysis.

Fix error in PEM electrolysis inventories (remove steam input).

v.1.6.6

Version bump.

v.1.6.5

Fix issue with testing for CCS variables in data_collection.py.
The issue caused CCS shares for cement and steel production to be 0% for all scenarios, hence important.

v.1.6.4

Fix reading of ecospold files
Fix export as Simapro file

v.1.6.3: Fix issue with `args` being None in marginal_mixes.py.

Fix error when no arguments are given with consequential system model.

v.1.6.2

Fix lead time when consequential
Fix inter year in fuels.py

v.1.6.1

Fix building of global hydrogen market sin scenarios with no hydrogen production
Fix linking to original DAC dataset

v.1.6.0

• Fix fuel market shares

v.1.5.9

• multiprocessing implementation
• refined electrolyzers' inventories
• add inventories for large-scale autonomous CSP
• export scenario difference files to Excel, CSV, and Feather formats