What is use for two slots on the right in heating tower?

[mirpa]

I can put any item in it, fuel or not, but I don't understand what they are used for.

[Amarula]

It may be for mods where fuel may have a by product, for example in Nullius a hydrogen fuel cell produces a water cartridge when it is used up.

[eugenekay]

The Heating tower is a nuclear reactor wearing a hat; normally a Reactor produces a Depleted fuel cell. It has been configured to use a BurnerEnergySource of type "chemical":

Code: Select all

      type = "burner",
      fuel_categories = {"chemical"},
      emissions_per_minute = {pollution = 100},
      effectivity = 2.5,
      fuel_inventory_size = 2,
      burnt_inventory_size = 2,
 

Note the burnt_inventory_size property matching the fuel_inventory_size. Heating Towers are capable of consuming a large amount of low-fuel-value burnables; having two slots makes it possible to load more fuel types simultaneously.

Good Luck!