The fuel tank is a camp building that is used to store fuel. With each additional fuel tank you built, extra storage space is granted. Please note that all fuel tanks share the same value of fuel stored, therefore if you have two fuel tanks both at 40, then you only have 40 fuel, not 80.  

Level Materials Required Storage Cap
1 40Resource-scrap metal2Resource-precious ore5Resource-screw 20
2 120Resource-scrap metal6Resource-precious ore15Resource-screw 40
3 200Resource-scrap metal10Resource-precious ore25Resource-screw 60
4 280Resource-scrap metal14Resource-precious ore35Resource-screw 80 (max)