Feature: Simple CO2
What does this feature / why does DuMux need it: Provide a "simple CO2" component in analogy to maybe simple H2O, which does not use the co2 tables, but e.g. ideal gas law and comparatively simple relations. This could potentially benefit setups/models using CO2 as a component far away from CO2-storage conditions, potentially reducing computational cost.
Which issue does this feature fix (if any) The current co2 component using co2 tables seems like over-complicated overkill for setups not investigating geological CO2-storage scenarios. Especially the biomineralization models (@hommel) do in many setups (including the the example) only require CO2 as a dissolved component in relatively low concentrations within the aqueous phase at +-atmospheric pressure conditions. Thus, for such setups, using the co2 tables feels like overkill. I am not 100% sure, but I think this might also be the case for the cave/karst evolution modeling by @leonidas.
Anything else we need to know?: Likely, this would also require new tests (in analogy to the current co2 tests? Other setups?) and binarycoefficients (e.g. simple_brine_co2.hh) to be created. I think it would also be good to investigate the differences between using such a "simple CO2" and the current CO2 using the co2 tables.