Nope. Can only change the temperature, not the element. The reason being that there is no universal way of changing it. Almost all buildings have something unique about them, so essentially I would need to patch each building individually. That would take a ton of time.
I made one exception with Algae Terrarium. That was difficult enough :P

Coal Generator only
CustomizeBuildings.json file (json file for manual change)
"Bed": {
"Rotations": 3
},
Under
"Generator": {
"GeneratorWattageRating": 1800
},

It can be solved by adding
"Generator" = (Coal Generator)
"GeneratorWattageRating" amount of power generated from building (600 for original, 1800 for example)

Oh, I thought this was about changing the element, but it was about power output.

First, thanks very much for the mod!! Love it!! Second, I am interested in upping the power generation of the coal generator, or any generator really. I see the line "Bed":3 in the json file, but not the line "Generator": { or "GeneratorWattageRating":

Do I need to manually add that? Or just add the line "Generator" = (Coal Generator)

Any help would be greatly appreciated!! Cheers!

It's a list. Json requires that you follow the formating rules. Values that are not present use default values instead.
So you add new entries with whatever ID you like and set any of the values you want to change.

Equal signs are illegal in json format, so I have no idea what you mean with that.

Thanks for the reply! Apologies for the confusion, I was referring to the post by Ernst above where they referenced changing the power generated by a coal generator. I am unsure what lines to add to the json file. Under where it says

"Bed": }
"Rotations": 3
},

If I add the lines

"Coal Generator": {
"GeneratorWattageRating": 1800
},

Will that work? Thanks very much for the help, and for the great mod!! Cheers!!

If you play with english localization, yes.

Thanks very much for the reply!! I'll give it a shot!! And thanks again for the wonderful mod!! Cheers!!

how do you play with english localization?

Start the game and select English as you language. Seems obvious. Note that this was a question regarding IDs.

You can always use the full ID and it will work in any language. If you cannot figure out the ID, you can use the full building name in your language instead of ID (but you do not have to).

Is it possible to just add a line for the output value like how the batteries or wires are formatted?

For instance, just add

"HydrogenGenerator": 1600.00,