6 points
For some reason I remember something like 8-12 fully grown oak trees being the minimum to sustain a person. I think it was in a thread about surviving in a bunker or fallout shelter.
Not a biologist though, so you’d better do your own googling
2 points
Wouldn’t algae be the most efficient at oxygen production? You’d still need about 1000L of water for the algae (assuming a 1L:1g ratio for the algae to thrive), the light source would hopefully be solar or else you’re using a lot of energy (good luck bunker people), and you’d have to have some method of feeding and filtering it (maybe its output can be something else’s input and vice versa?), but it’s a little more doable than 8-12 oaks.
