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Researchers made a breakthrough in 2015 when they showed that it is possible to get a certain kind of bacteria to produce methane by feeding them with water, electricity and carbon dioxide. They will now use the methane as a nutrient for another type of microorganism that can grow to become sustainable biomass in large tanks.

Great potential was shown last year when Danish researchers demonstrated that they could use certain types of microorganisms to design a microbial electrosynthesis that converts surplus power from wind turbines into methane gas as a stable energy carrier.

“One of the major challenges in converting to a sustainable energy society is finding new solutions to how we can store surplus power from fluctuating energy sources such as solar and wind. We believe that biotechnology can come to play a key role,” says Associate Professor Lars Ditlev Mørck Ottosen.

The researchers expect that the new method for producing methane gas can be implemented within five years and become an important technology for storing electricity in the form of methane that can be integrated into the natural gas grid as required.

The electricity-eating bacteria can in principle produce other conceivable forms of biomass, but methane has the distinct advantage that it is a gas with a very low solubility and can therefore be purified by bubbling through a solution.

New bacteria grow with methane
The researchers have therefore also started to experiment with using methane from the electricity-eating bacteria to feed another type of bacteria that appear to be eager producers of biomass.

Hereafter, the biomass can be subsequently used for everything from fossil-free fuel to protein-rich animal fodder, which only requires minor genetic modifications of the microorganisms.

“Progress in biotechnology opens up for a completely new way of producing biomass and storing energy. If we can store surplus power from wind turbines in methane, and if we can use methane to produce sustainable biomass while maintaining carbon dioxide in the process, then the technology has very great prospects for the energy society of the future,” says Associate Professor Ottosen.

Together with his research colleagues and industrial partners, he is experimenting with getting microorganisms to act as small energy factories, and they have already made an initial proof of concept.

In a large tank, the researchers will get methane and oxygen to bubble into a solution containing bacteria. Here the bacteria will breathe the oxygen and eat the methane after which they will grow rapidly. In the course of a short time, they will produce an energy-rich biomass that can be concentrated.

“It’s basically a thick soup of bacteria that can be concentrated to an organic material, and this can subsequently be used for purposes such as animal fodder and food ingredients,” says Associate Professor Ottosen.

Exactly how the bacteria produce the organic material and whether it is possible to get them to produce it in a profitable amount has not yet been clarified.

Sustainable biomass in tanks

Another interesting prospect in the microbial production of biomass is that it can possibly become an alternative or supplement to traditional biomass from agriculture.

In the coming years, the world will need to limit the use of fossil fuels, and the total land area available for cultivating biomass will get smaller. Finding new methods to produce biomass and store energy is therefore a matter of urgency.

“We need to develop the technologies for producing sustainable biomass and energy that we can use for electricity, heating, food, petrol, plastic and much more in the future,” says Associate Professor Ottosen.

To start with, the researchers will closely study the ability of the microorganisms to produce biomass directly from electricity in the tanks at Aarhus University.

PHOTO TOP: s it possible to cultivate bacteria and get them to grow in tanks to become valuable biomass? Researchers will boost the microbial process and create a sustainable supplement to fossil fuels and traditional biomass. Pictured here in the laboratory is PhD student Laura Mia Agneessens. (Photo: Lars Kruse)