Here is a research update for the project

https://www.sciencedirect.com/science/article/pii/S2405653716300835 -  super info

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4385132 cabon as electrode material

https://www.researchgate.net/publication/322715435_The_Effect_of_Increasing_Surface_Area_of_Graphite_Electrode_on_the_Performance_of_Dual_Chamber_Microbial_Fuel_CellsThe_Effect_of_Increasing_Surface_Area_of_Graphite_Electrode_on_the_Performance_of_Dua

increasing surface area = increase mah output

terra cotta as a pem, it looks promising BUT there are many details that are not avail to do this as a DIY home project and in the efforts of OPEN and DIY I will stick with more avail materials

https://link.springer.com/article/10.1007%2Fs00449-013-0967-6

Study on Agar as a electolytic / PEM

https://aip.scitation.org/doi/10.1063/1.5029150

A BI POLAR membrane,  two membranes in dual chamber with center transitional chamber

https://www.tandfonline.com/doi/full/10.1080/21553769.2016.1230787