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The Project

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- Overview

  • Défi H12 is a research program on Bioenergies (ANR-09-BIOE-10) funded by the French National Research Agency from 2009 to 2013.
  • The production of bio-hydrogen by fermentation exploits simple carbohydrates (sucrose, glucose), polysaccharides (molasses) and even hemicellulosic compounds. Productivities obtained through this alternative are interesting (about few liters of hydrogen per liter of reactor per hour) but yields remain limited to 2 to 3 moles of hydrogen produced per mole of hexose in mixed culture, thus far from the theoretical stoichiometric limit of 12 moles of hydrogen per mole of glucose. Moreover, volatile fatty acids, mainly acetic and butyric, appear as inconvenient byproducts. The project DéfiH12 proposes to convert the organic acids produced by fermentation in hydrogen, taking advantage of the "Microbial Electrolysis Cell (MEC)" technology. A MEC is an electrolyzer which makes the oxydation of acetic/butyric acid at the anode, while at the cathode it ensures the classical abiotic reduction of water. In fact, oxidation at the anode is catalyzed by a microbial biofilm that acts as an electro-catalyst.
  • MEC technology, invented in 2005, has already demonstrated its capacity to produce 3 moles of hydrogen per mole of acetate, so coupling fermentation and MEC would lead for a total of 8 to 9 moles of hydrogen per mole of glucose, being a significant step towards the theoretical limit of 12 moles of hydrogen. There is a lack of fundamental knowledge on the electro-microbial catalysis mechanisms at the anode, which remains an obstacle to the development of MEC. DéfiH12 aims to form specific microbial biofilms for the development of MEC-anodes, identifying innovative sources of inoculum, adapting the microbial populations and determining the structural characteristics of the biofilms that optimize their electro-active properties. This basic research will couple tightly microbiology, molecular biology and electrochemistry. Fundamental knowledge created will be used to design a prototype within the rules of electrochemical engineering, for obtaining a system beyond a laboratory cell which foreshadows an industrial pilot capable to provide reliable information to assess the potential production of bio-hydrogen by electrolysis of organic matter.