Harvesting Electricity

A project log for Moss Microbial Fuel Cell

Harvesting electricity with the help of moss dwelling microorganisms!

guru-sanGuru-san 04/29/2022 at 20:070 Comments

The microbial fuel cell only produces a small amount of electricity, in the range of a few hundreds millivolts and current depending on the surface area - but for the ~0.06m^2, we are looking at a few dozen microamps. 

Making use of such a small power is no easy feat but thanksfully there are a few ICs specially designed for energy harvesting. 2 specific ICs caught our eyes:

- The SPV1050, able to work from 75mV, doesn't require tuning and is available as a devboard (MIKROE-3814 Peltier Click) However the low current performances are not great, it needs in the range of ~10uA to 100uA to function efficiently.

- The BQ25504 works at a slightly higher minimum voltage of 130mV, requires to be started at 600mV and needs to be configured as well. However the low current performances seem to be significantly better!

Both of these have their pros and cons, and so we will test both and see which one works the best. The BQ25504 will require a bit more homework but we got our hands on the Peltier Click devboard!

A short test shows it can charge a 10uF capacitor to 4.2V (maximum voltage since the circuit tries to charge a lithium ion cell) over a few days! 

Next time! 

Design of a better Microbial Fuel Cell casing and especially improving the anode and cathode will hopefully lead to better performances~