COOMET – A second chance to CO2

Climate change and future depletion of resources are two of the most important environmental challenges that humankind has ever faced. Emissions of carbon dioxide (CO2) and its accumulation in the atmosphere are on the basements of these problems. European Union has committed to achieve an economy-wide domestic target of at least 40% greenhouse gas (GHG) emission reductions for 2030 and at least 80% GHG reductions by 2050. Carbon dioxide capture and utilisation are expected to play a relevant role in reaching these targets. Moreover, efforts oriented to the development of Carbon-neutral and Energy-saving technologies are more than welcomed. One such technology is fundamentally based on microbial electrochemistry technology (MET), a promising method of carbon fixation that is currently under continuous development. The COOMET project puts forward an oriented based research plan, to increase resilience and sustainability of a newly developed biorefinery concept based on electrode-driven microbial reactions. We aim at giving a second chance to CO₂ by providing a platform to capture it from industrial emissions, and convert it into valuable platform chemicals: carboxylic acids (i.e. butyrate and caproate), and alcohols (ethanol and butanol). Both groups of C-neutral compounds are key building blocks for further chemical transformations in the pharmaceutical, cosmetic, chemical, and transport industries. Carbon transformation in the COOMET project relies on the application of a structured and synergic combination of three key aspects, energy utilisation, electric power to chemical energy conversion, and biocatalysts. We bet for exploring the use of MET beyond the currently proposed possibilities and provide a new platform to increase the production power towards longer C-chain products. The COOMET is envisioned as a two-step platform, in which separate reactors and changing operation conditions are applied. This configuration seems to be a way to control the specific final product obtained. In first step, CO2 will be converted to acetate using in-situ produced bio-hydrogen (H2). The goal of this step is to steer MET-dependent production beyond the formation of acetate in a simple, robust and efficient platform. In second step, specific chain elongation process will take place by controlling physicochemical parameters and H2 and CO2 concentrations. COOMET project will work on three main fronts. First, at the system set-up level to evaluate different modes of operation and the physicochemical conditions which conducted to an efficient performance. Second, basic knowledge of kinetic parameters, regulatory mechanisms of metabolic shifts, and effects of environmental variables on growth, will be studied for model metabolic hydrogen producers and homoacetogenic organisms. Third, at the process level modules will be integrated in the platform, performance of first-stage (acetate production), second stage (chain elongation or reduction into carboxylates and/or alcohols) and separation process will be thoroughly explored in terms of economic and environmental indicators.