Closing the loop

At an advanced stage now where all research is done and I'm basically trying to exhaust all expeditions. Settlement is calm and peaceful, however my settlers would like to conduct some novel research. May I suggest these to the MAA (I.e. game admin)?

CO2 is being vented, but we'd like to use Sabatier reaction to provide methane and sell to MAA for return trips. Would obviously need a structure, use energy and other resources.

Secondly, Biomass is building up and thrown away. I would suggest that the large habitats might have gardens that would use some biomass during repairs. Alternatively, a waste to energy plant.

Just feels wrong not being able to close this loop.