Bio-E - Bioénergies

Conception basée sur la connaissance de piles à combustible microbiennes pour la production d'électricité à partir de déchets des filières agricole et forestière – AGRI-ELEC

Electrical energy produced from agricultural and forest residus

From waste to power: transform directly into electrical energy the chemical energy contained in waste becomes possible thanks to the microbial fuel cell (MFC) technology.

Des microorganismes qui catalysent les réactions électrochimiques

The principle of microbial fuel cell is based on two electrodes: the anode oxidizes the fuel and injects the electrons produced into the electrical circuit; the cathode extracts the electrons from the circuit, most often by achieving oxygen reduction. Intensity of the current that flows through the electrical circuit depends on the rate of both electrochemical reactions. It was discovered in the early 2000s that some microorganisms are able to form on the surface of electrodes biofilms that catalyse electrochemical reactions and, particularly, the oxidation of a lot of organic compounds (acetate, sugars, alcohols, volatile fatty acids…). This is a major scientific breakthrough, which opens a very promising path because it becomes possible to feed fuel cells with a large variety of renewable matters such as residues from agriculture and forests. The so-called microbial fuel cells (MFC) allow the chemical energy contained in wastes to be transformed directly into electrical energy.

The objective of the AgriElec project is to evaluate the potential of MFC for power generation from paper industries effluents and agricultural waste (wheat straw, corn stover). The first step of the project aims to identify microorganisms capable of catalyzing the electrochemical oxidation of these compounds. Flora of soil and effluents will be investigated first. The rich biodiversity of Amazonian environments (Guyana) will also be investigated with great care for finding electroactive microorganisms. A procedure for formation of microbial biofilms was defined to facilitate the development of bacteria of interest and optimize the electron transfer rate at electrode-biofilm interfaces. Electrochemistry will be combined with the analytical tools of molecular biology and with microscopy imaging techniques to establish correlations between the electroactivity of biofilms, their structure and their microbial composition. Surface structuring at the micro- and nano-sizes are being tested in order to improve the colonization of the surface of the electrodes by micro-organisms of interest. Much research will be devoted to microbial anodes. For the cathodes, the an abiotic strategy will be pursued with the development of air cathodes and a biological pathway with the implementation of strains capable of catalyzing oxygen reduction.

At the beginning of the project, the highest current densities reached by MFC technology were around 10 to 20 m2. In October 2011 a German research group clinched the record with 30.8 A/m2. The project has identified new environments that offered microbial communities able to form electroactive biofilms very effective on the anode. Current densities above 50 A/m2 are now obtained for potentials below 0 V/SHE, values that are currently the best current performance. Studying mechanisms of electron transfer showed that current densities of 65 A/m2 can be achieved, which represents a world level advance. For catalyzing oxygen reduction, a strain has been identified that will allow the first mono-species microbial cathode to be designed. A patent on a new cell design that allows MFC to increase their life time has been taken out.

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A lot of results have been presented in national and international congresses, three articles have been published in the best journals of their category (IF 4 to 9) more than ten articles are submitted or in preparation, two patens have been taken out.

Project coordination

Alain Bergel (Autre établissement d’enseignement supérieur)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

COMMISSARIAT A L'ENERGIE ATOMIQUE - CENTRE D'ETUDES NUCLEAIRES DE FONTENAY AUX ROSES
COMMISSARIAT A L'ENERGIE ATOMIQUE - CENTRE D'ETUDES NUCLEAIRES DE GRENOBLE

Help of the ANR 1,167,610 euros
Beginning and duration of the scientific project: - 48 Months

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