Researchers have developed a microbial rechargeable battery (MRB) that is driven by bacteria and can discharge stored solar energy over an eight-hour period. This battery operates in two stages; in the first stage microbial electrosynthesis (MES) process is used to produce acetate, using bacteria in a CO2 environment. The bacterium uses excess energy from the solar panel to fix or reduce CO2 into acetate and various other molecules. In the second stage, a microbial fuel cell (MFC) is involved in breaking down of the stored acetate by exoelectrogenic (electricity producing) bacteria coated onto a bioanode. These exoelectrogenic bacteria consume the acetate and produce electrons which are collected by the bioanode and then discharged, when needed, like a battery.
This battery was developed by researchers from the Netherlands’ Wageningen University (WU) and the research institute Wetsus. They say that the MFC can operate on a 24- hour cycle, with 16 hours’ worth solar energy required to charge the battery. The battery can be discharged for up to eight hours, mimicking the day-night pattern typical for solar energy production.
The energy conversion efficiency is currently 40% of lithium-ion batteries. The team plans to optimize the system and tackle the challenges of maintaining the current efficiency levels at higher power densities, by developing a better counter electrode. The team believes MRB will be more beneficial after overcoming the challenges, considering the manufacturing cost and safety concerns of conventional lithium batteries.