Good efficiency microbial batteries breathe methane and convert it into electricity

Methane contributes significantly to the exacerbation of global warming. And recently, scientists have found what appears to be a vital method that may help get rid of its harmful effects and turn it into a useful form of energy.

Methane is the most dangerous greenhouse gas that causes global warming, as it can trap heat 25 times more efficiently than carbon dioxide.

However, there is another beneficial aspect of methane, even if it is not as efficient. Less than half of the energy in natural gas can be converted into electrical energy when burned. Therefore, scientists are seeking ways to harvest more electrical energy that results from the combustion of methane.

Bioenergy plants

Recently, a research study - published in Frontiers in Microbiology on April 12 - revealed an unconventional form of a microbial power plant that can harvest more methane energy.

According to the press release published by the Dutch Radboud University, commenting on the study, microorganisms act as plants for the production of biological methane. The turbines are then turned on when the gas from these vital plants is burned, which ultimately generates power.

Of course, this process could be very beneficial for the energy sectors. But it's not very efficient, explains Cornelia Welty, microbiologist and study leader: "Less than half of biogas is converted into energy, and that's the maximum capacity we can achieve."

According to a report published by the "Science Alert" website, scientists have focused their efforts on a type of archaea (microorganisms similar to bacteria) known for their ability to survive under the most difficult and harsh conditions. These microorganisms are known as 'anaerobic methanotrophic archaea'.

Methane oxidation plants

These archaea can break down methane in oxygen-free environments. So the absence of oxygen doesn't help them, and these archaea use a metabolic trick to convert methane into a harmless form of energy. Archaea do this metabolic trick by discharging electrons (the elementary particles responsible for the transmission of electrical energy) in a series of electrochemical reactions, modulating some minerals outside their cells.

The archaea under study belonging to the genus Methanoperedens were first classified in 2006. Scientists discovered that they are able to oxidize methane in the presence of little nitrate. Hence, these archaea live in wet swamps and farmland rich in fertilizers. However, previous efforts to harvest more electrons from this process failed to produce a small effort of electrical energy.

To solve this problem, the team collected a sample of microbes that they believe contain an abundance of methanophilic archaea and cultured them in an anoxic environment. Thus, the only source of electrons in this environment is methane.

Good quality batteries

The research team also placed near this colony a positive electrode (an anode, which acts as an electrode that allows electric current to pass through it) with zero voltage. Thus, they created an electrochemical cell designed to generate and transmit electric current.

Helen Opoter, the first author of the study, explains the mechanism of this battery formation, saying, "In this way, we made a battery with two sides, one biological and the other chemical." Archaea implanted on one of the electrodes supply the battery with electrons from methane oxidation.

The research team concluded, after measuring the fluctuating electric currents generated, that the archaea were able to convert 31% of methane energy into electrical energy, which makes these precise electrical stations comparable - to some extent - to the efficiency of some power stations, which are barely methane conversion efficiency in some 30%, the report states.

In the future, optimizing this bio-process may lead to the design of bio-batteries based on biofuels, which could reduce the damage caused by methane.

Source : Science Alert + Al Jazeera