Generating power while purifying the environment of greenhouse gases is a goal of many environmental technology programmes, but success has been hampered by technological challenges. Despite this, theoretically should be achievable using bacteria.
In a new publication a way forwards has been charted. Here, microbiologists from Radboud University have demonstrated that it is possible to make methane-consuming bacteria generate power in a laboratory.
For the process the researcher used the archaea Candidatus Methanoperedens. This organism uses methane to grow. The anaerobic organism oxidizes methane by coupling to nitrate reduction.
These archaea naturally occur in fresh water such as ditches and lakes. As an example, in the Netherlands, the bacteria mostly thrive in locations where the surface and groundwater are contaminated with nitrogen, as they require nitrate to break down methane.
For the experiments, researchers initially wanted to know more about the conversion processes occurring in the microorganism. In addition, they were curious as to whether it would be possible to use it to generate power.
In current biogas installations, methane is produced by microorganisms and subsequently burnt, which drives a turbine, thus generating power. An inefficacy with this process is that less than half of the biogas is converted into power, and this is the maximum achievable capacity. We want to evaluate whether we can do better using microorganisms.
As an alternative, it is possible to generate power using anammox bacteria that use ammonium during the process instead of methane. This involves creating a kind of battery with two terminals, where one of these is a biological terminal and the other one is a chemical terminal.
The researchers can grow the bacteria on one of the electrodes, to which the bacteria donate electrons resulting from the conversion of methane.
Through this approach, the researchers managed to convert 31 percent of the methane into electricity. In the longer term, they are aiming at higher efficiencies.
The research appears in the journal Frontiers in Microbiology, titled “Methane-Dependent Extracellular Electron Transfer at the Bioanode by the Anaerobic Archaeal Methanotroph Candidatus Methanoperedens”.
