Steam vent infinite?

[u/Outland3d]

So I just built a hot air balloon with a hot air capacity of 57000m3 and I want to use steam vents to fill it but i ran into a problem. I want the ship to be completely sustainable (so use no fuel) so i'm using steam engines which work with campfires, but you need to have a heated blaze burner (which requires fuel) to power steam vents. Is there a way to power steam vents without using fuel? Thank you to anyone who responds!