Free-Methane: Producing Fuel from Waste CO₂ Using Renewable Energies

A research aiming at reusing waste CO₂ through a prototype methanation reactor (ProGeo) producing carbon–neutral methane by renewable energies was carried out. Preliminary determinations of methane yields by ProGeo have been performed using CO₂ either by commercial bottles as well as from grapes fermentation. The obtained results show a complete compatibility with the used commercial catalyser. The ProGeo reactor was designed to produce a CH₄ flux of 1 Nm³/h by the Sabatier reaction at a high pressure (2–3 atm) and temperature (200–300 °C). The main goal of our research is to use either low cost or renewable energy to reuse waste CO₂ to produce methane in a circular economy scheme. To this end, we have also undertaken the investigation of a new methanation pathway aimed at avoiding the use of the solid catalyst, by exploring mechanisms involving a plasma generation by electrical discharges or by vacuum ultraviolet (VUV) photons on CO₂ + H₂ gas mixtures. Our research aims to provide a better scientific understanding and a guide to zero-emission technologies to allow industry and regional authorities’ future strategies for energy innovation and sustainable development.