This mod adds new types of fuels like methane gas, thorium, kerosene, etc. For the questlines to began, talk to the miner after completing the "factory" quest. Miner had found a strange cave with strange ores and enemies. Help miner to clear the way. The cave will only spawn in that area where you talked to the miner for that quest. Dig underground to find the cave once you have that quest.
1) If you didn't defeat the final boss and talked to the miner, the cave will spawn in the starting island under the ground.
2) If your colony is starting island(defeated final boss) and talked to miner for the quest, the cave will spawn in the starting island under the ground.
3) If your colony is earth.desert(defeated final boss) and talked to miner for the quest, the cave will spawn in the earth.desert under the ground.
4) If your colony is colony island(defeated final boss) and talked to miner for the quest, the cave will spawn in the colony island under the ground.
The cave will spawn in one of the areas according to the conditions listed above.
This is spoiler don't see this if you want this mod to be adventurous.
In that strange cave, there are butanol and thorium ores. Show builder the butanol ore found at that strange cave, he will give you a new quest which would discover a new fuel. Also, the enemies in that cave are butanol stinger and thorium wyrm. You can catch them, equip them as familiar, and can put them into a coral pen or wyrm pen.
Thanks to jimmy_the_angel for correcting grammar and spelling.
Enjoy the mod and if finding any bug or want to give any suggestion then you are free to write it in comments.
If you are finding any difficulty in searching the strange cave, a video had been uploaded aside which shows the way to the cave. But the locations may differ if you didn't select your colony as starting island.