Microbiologists have proposed a novel means to generate power and clean-up an environmental pollutant through the same reactive process.
This is based on a proof of concept study where Radboud University Nijmegen scientists have successfully demonstrated that it is possible to make methane-consuming bacteria generate power. So far this has only been demonstrated within the laboratory setting, although the potential exists for scale-up.
The technology uses methane-consuming bacteria (methanotrophs) to generate power. The bacteria metabolize methane, which they used as their source of carbon. The metabolic process unlocks the energy of oxygen, nitrate, and sulphate. Earlier studies have shown how the bacterium Methylococcus capsulatus can be used to produce animal feed from a natural gas source.
Methanotrophic bacteria are estimated to consume 30 million metric tons of methane per year. This leads to the possibility that these organisms have the potential to convert what is a potent greenhouse gas into usable fuel.
This has been hampered by the workings of the complex reaction occurs being difficult to decipher, ahead of the new advancement.
The new study looks at the bacterium Candidatus Methanoperedens, which uses methane to grow and naturally occur in fresh water such as ditches and lakes. These organisms tend to thrive in locations where the surface and groundwater are contaminated with nitrogen (this is because they require nitrate to break down methane).
According to lead researcher Cornelia Welte, the detailed understanding of the process: “Could be very useful for the energy sector. In the current biogas installations, methane is produced by microorganisms and subsequently burnt, which drives a turbine, thus generating power. Less than half of the biogas is converted into power, and this is the maximum achievable capacity.”
She adds: “We want to evaluate whether we can do better using microorganisms.”
Other studies have shown that it is possible to generate power using anammox bacteria that use ammonium during the process instead of methane. The understanding here was applied to the methane consuming organisms.
This led to experiments that created a kind of battery with two terminals, where one of these is a biological terminal and the other one is a chemical terminal. Here bacteria are grown on one of the electrodes. These organisms donate electrons resulting from the conversion of methane and the generation of power.
In tests the scientists succeeded in converting 31 percent of methane into electricity. The next wave of study will aim to make this process more efficient. Additionally, methanotrophs could potentially decrease overall net methane emissions.
The findings appear in the journal Frontiers in Microbiology, titled “Methane-Dependent Extracellular Electron Transfer at the Bioanode by the Anaerobic Archaeal Methanotroph “Candidatus Methanoperedens”.
