What if bacteria could be used to create hydrogen biobatteries?
A paper published in Joule shows that these types of batteries could perhaps be used to store and release hydrogen.
Green hydrogen, which is produced from water with the help of renewable energies, is one of the carbon-neutral energy sources that could become an effective alternative to fossil fuels. However, transporting and storing this highly explosive gas is difficult, and researchers worldwide are looking for chemical and biological solutions.
A team of microbiologists from Goethe University Frankfurt has found an enzyme in bacteria that live in the absence of air and bind hydrogen directly to CO2, producing formic acid in the process. The process is completely reversible – a basic requirement for hydrogen storage.
These acetogenic bacteria are found in the deep sea and they feed on carbon dioxide, which they metabolise to formic acid with the aid of hydrogen. Usually, this acid is just an intermediate product of their metabolism. However, the team led by Professor Volker Müller, has been able to adapt the bacteria to not only stop this process at the formic acid stage, but also to reverse it, and develop a biobattery for hydrogen storage from it.
"Unlike chemical catalysts, the bacteria do not require rare metals or extreme conditions for the reaction, such as high temperatures and high pressures," Müller said.
Moreover, Fabian Schwarz, another member of the team, has been able to drive this research by developing a bioreactor that will complement the biobattery.
To do so, he fed the bacteria hydrogen for eight hours and then put them on a hydrogen diet during a 16-hour phase overnight. The bacteria then released all the hydrogen again, allowing the elimination of the unwanted formation of acetic acid with the help of genetic engineering processes.
"The system ran extremely stably for at least two weeks," Schwarz explained.
As part of the UK's drive to decarbonise its gas infrastructure, the country is being prepared to accept a blend of up to 20 per cent hydrogen, something perceived as necessary in light of rising energy prices.
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