I have checked in the paper (and online in general) and black coal is considered to have some different characteristics than brown coal. I think this is why they keep on differentiating it in the models. However, can we consider them to be one element? And accept this "abstraction" at least for the first version? Would it be helpful?
The difference between those variables are the measurement units. In the initial model, there are many variables with the same name but different measurement units. I think this happens in order to be able to connect the same variable with different elements that require a different unit in order to "mathematically coexist" (sorry for my abstract explanation of this). Maybe we can merge them? But I am not completely confident yet because this might change other relationships.
I also thought that this type of data can be found and incorporated for our case study (Netherlands). I just thought we should have an initial list of what was missing in order to be able to reference our additions in the future.
I hope I answered your questions, however, if something else arises please let me know :)
I have some questions for the list of missing variables/stocks
#-(CO2-e)
and# - (CO2-e)
where # is, e.g., oil, gas, etc.?