I was under the impression that Vulcanus would have no coal and no oil, but i was wrong, there is coal, but no oil, so oil cracking is still possible which require liquid water but that would be after coal liquefaction, which require steam, but using 500°C steam is a waste compared to using 100°C steam in such case so i think there will be something related to this.
Water seem like it would be a very interesting ressource to manage, and i'm expecting a cold planet too after seeing the hot one, and as it was mentionned in the thread something related to ice.