update `charging`

[stap-m]

Description of the issue

Charging is classified as electrical energy transfer, which seems wrong.

One could interpret the temporal electricity storage with subprocesses charging and decharging as electrical energy transfer, though.

Maybe also related to #1407

Ideas of solution

Charging should be classified as energy transformation, in which electrical energy is transformed into another kind of energy, e.g. chemical energy in a battery. We could also think of defining the charging process in a larger context, as filling an energy storage of any kind. Then we could refine the processes into battery charging and others.

Workflow checklist

• [ ] I discussed the issue with someone else than me before working on a solution
• [ ] I already read the latest version of the workflow for this repository
• [ ] The goal of this ontology is clear to me

I am aware that

• [ ] every entry in the ontology should have a definition
• [ ] classes should arise from concepts rather than from words

[stap-m]

Once we have #1407 we could make charging equivalent to an increase of the energy storage level.

[l-emele]

The existing class comes from the inclusion of electric vehicles where energy is transferred from the electricity grid to the vehicle.

I think we have to differentiate between two processes:

• The energy transfer to the battery (currently labeled as charging).
• The energy transformation process in the battery (or other other any other energy storage object) itself.

[stap-m]

I think we have to differentiate between two processes:

• The energy transfer to the battery (currently labeled as charging).
• The energy transformation process in the battery (or other other any other energy storage object) itself.

charging should thus be the overarching process, that combines the subprocesses of energy transfer and transformation. E.g. battery charging

• equivalent to 'energy transformation' and 'has energy input' some 'electrical energy' and 'has energy output' some 'chemical energy'
• AND describing the energy transfer, tbd once determined in #1527

[l-emele]

energy storage (process) should be discussed together with charging, see #1622. Such a process only makes sense, when charging and discharging are referenced as subprocesses. Without them, storage is not process-like or a transformation (i.e. nothing is evolving in time etc.), but rather "continuant".

Originally posted by @stap-m in https://github.com/OpenEnergyPlatform/ontology/issues/1539#issuecomment-1779179734