Comparative Analysis of Carbon Dioxide Methanation Technologies for Low Carbon Society Development

Conversion technologies able to transform renewable energy sources (RES) based electricity in gaseous fuels, which can be stored over long timeframes, represent a key focus point considering the low carbon society development. Thus, Power-to-Gas technologies emerge as a viable solution to mitigate the variability of RES power generation, enabling spatial and temporal balancing of production vs. demand mismatches. An additional benefit in this context is brought by the decarbonization facilities, employing polluting carbon dioxide (CO2) emissions and RES-based electricity to produce synthetic natural gas with high methane (CH4) concentration. The fuel obtained can be stored or injected in the gas distribution infrastructure, becoming a clean energy vector. This paper investigates the functional parameters of such technologies, aiming to comparatively analyze their suitability for further integration in hybrid and ecofriendly energy systems. Given the stability of CO2 molecule, a catalyst must be used to overcome the methanation reaction kinetics limitations. Therefore, the required conditions (in terms of pressure and temperature) for CO2 methanation reaction unfolding are analyzed first. Further, CO2 conversion rate and CH4 selectivity are investigated in order to provide a detailed comparison of available technologies in the field, addressing moreover the particularities of catalyst preparation processes. It is found that Nickel (Ni) based catalysts are performing well, achieving good performances even at atmospheric pressure and low temperatures. It is remarkable that, within a [300,500]℃ temperature range, Ni-based catalysts enable a CO2 conversion rate over 78% with a CH4 selectivity of up to 100%. Last, integration perspectives and benefits are discussed, highlighting the crucial importance of the results presented in this paper.