Methane biofilter
This could be a biological battery at methane producing sites where the methane is capturable.
What if you made a system that used methantrophic bacteria with algae in an initial section that lead to a section with plants (potentially food producing plants, maybe covered also in methantrophic bacteria), converting the initial methane into CO2 then O2? Then a section that digests the produced excess biomass with fungi creating soil.