Dear Alex,

1. "Electricity is generated with a kind of organic "fuel cell", without rare metals, may be it may inspire other development as well" - Yes, indeed many efforts have been made in the area but efficiency is depends very strong on the microbial metabolism. We are working in how the nutrition of microbes affects the bio-electricity production. For example, a key nutrient is the dosage of calcium in the culture media to enhance bio-electricity production.

2. " No methane is produced without recuperation and what the efficiency is bio-electricity is". The methane production depends on how to control de oxygen concentration to let the anaerobic microorganisms to work. One can achieve a sufficient oxygen concentration very easily to manage both aerobic and anaerobic microbes to growth; so, avoiding methane production.

3. " Bio-electricity could power light in homes, avoiding batteries with rare metals, or high energy components (Lithium), or heavy metals such as lead " - Yes, indeed. Please take a look in the following link: https://www.youtube.com/watch?v=_zCsAfEbVRc&t=15s

Yes, indeed, it would be very interesting to understand more about the electron transfer mechanisms!

Thanks.

The youtube is simply marvellous, 0.83 V is also not that bad. PV electricity is the cheapest now, but not when it has been stored in a battery. Still some efficiency or figure of merit could be imagined: How much watt/kg, what energy out compared to biomass input. Good luck!