Technology capable of transforming aquatic microorganisms into methane gas developed at EPFL and the Paul Scherrer Institute could play a role in the perspective of sustainable biogas production.

A green light seems to emanate a strange “window” installed this week in a pavilion on the Federal Square in Bern. On the sidelines of the Swiss Energy and Climate Summit, the bioreactor demonstration illustrates the operation of a biogas technology particularly promising, developed by Christian Ludwig and his team.

Its “gas plant” a new kind of combine the advantages: “On the one hand, the growth of algae consumes CO2 from the atmosphere, says Christian Ludwig sidelines of his presentation on Friday in Berne. During processing, it emerges again, but in a concentrated form which lets consider opportunities of storage in the basement. This system can also produce renewable biogas, without competing with food crops. ”

Algae have on other sources of biomass, the advantage of “push” much faster. Under the right conditions, they can generate about 120 tons of dry matter per hectare per year – tens of times more than other sources such as corn, soybeans and sugar cane. “It is especially possible to grow above ground, just in bioreactors exposed to the sun, which avoids encroaching on fertile land needed for food production,” says Christian Ludwig.

Closed circuit

The process outlined this week, known as the SunCHem transforms the biomass into methane through catalytic hydrothermal gasification of. “This device eliminates the need of solvents and completely satisfied with a non-potable water, add Mariluz Bagnoud, scientific collaborator at the Institute of Environmental Engineering at EPFL. In addition, the nutrients necessary for the growth of algae, such as phosphorus, are collected along the way and back into the culture medium. This is an important step because it is also a limited resource. ”

The environmental impact is minimal, and yields dramatic: from 60 to 70% of the energy potential of the biomass produced in these “photo-bioreactors” can be recovered in the form of gas, with all the advantages that entails in terms of transport and use – it is sufficient to inject in existing distribution network. “We pass under review the entire chain, choosing the type of algae and their cultivation to processing gas to determine the best solutions for each step, says Christian Ludwig. Regeneration of our catalyst ruthenium is the challenge we are working on today. ”

The gas will play an important role in energy supply in the coming decades.

Switzerland relies on gas power plant, for a phase transition in the output of the atom. “Sustainable production and decentralized biogas, not requiring condemnation of farmland for food, has many advantages that are now to exploit,” says Christian Ludwig.

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