Misleading variable names: Coal

[felixfrischmuth]

When checking the nomenclature with our model output, I got two warnings. This leads me to this issue.
In the nomenclature (nomenclature/nomenclature/definitions/variable/technology/technologies.yaml) is the differentiation between "Coal” and "Lignite". I would suggest differing between „Hard Coal“ and „Lignite“, and maybe “Coal” for sum them up.
In nomenclature (nomenclature/nomenclature/definitions/variable/energy/...) there is only the variable "Coal". It should also include "Lignite" and "Hard coal", e.g. Secondary Energy|Electricity|Lignite.
If you think this too, I can do a pull request?

[tburandt]

I support the suggestion of @felixfrischmuth to add the different subtypes of coal and provide a uniform way of handling it. So, I would propose to also add "Coal" for summing up the secondary energy variables as well as the technology variables.

E.g.:

Secondary Energy|Electricity|Coal
Secondary Energy|Electricity|Coal|Lignite
Secondary Energy|Electricity|Coal|Hard coal

and

Capacity|Electricity|Coal
Capacity|Electricity|Coal|Lignite
Capacity|Electricity|Coal|Hard coal

but of course for all related variables

[arght]

In that regard we may also add bituminous and sub-bituminous coal if anybody is willing to use them

[sandrinecharousset]

I support the suggestion of @felixfrischmuth to add the different subtypes of coal and provide a uniform way of handling it. So, I would propose to also add "Coal" for summing up the secondary energy variables as well as the technology variables.

E.g.:

Secondary Energy|Electricity|Coal
Secondary Energy|Electricity|Coal|Lignite
Secondary Energy|Electricity|Coal|Hard coal

and

Capacity|Electricity|Coal
Capacity|Electricity|Coal|Lignite
Capacity|Electricity|Coal|Hard coal

but of course for all related variables

I agree :-)

[danielhuppmann]

I also agree with this suggestion (in the sub-category format of Coal as suggested by @tburandt)!

@felixfrischmuth if you need this urgently, please go ahead and start a PR - otherwise, it might make more sense to wait until I make a PR to implement a generic identifier (see #29), so that you don't have to add the coal disagggregation for every fuel.