This paper is dealing with the modeling, simulation and optimization of Hybrid Generation systems integrating Renewable Energies (PV, Wind turbine, etc.) an electrolyzer for Hydrogen production and a Methanizer for Methane production. We present a case study with a pre feasibility simulation under a system analysis environment for a cement production plant. The aim is to minimize the contribution of fossil sources to the cement production process while reducing CO2 and other greenhouse gases emissions. The environmental and social impacts are significant for neighboring areas nearby the cement plant and contribute also to methane gas storage for electricity profile picks shaving.