The methanation of CO2 has been increasingly discussed for the potential long term storage of electricity and for facilitating grid load management. Using the regions of northern Germany as a case study, the feasibility of CO2 conversion from biogas plants and its integration in existing natural gas grid was examined in this study. Furthermore the material and energy flows of in the methanation process, were evaluated to provide expression for the quantities of excess electrical energy which could be potentially stored using the biogas integrated systems. The study results showed that with 480 biogas plants in the region would be able to utilize up to 0.7 TWh surplus electricity could be used to produce 100 10(6) m(3) at standard temperature and pressure of upgraded methane per year. (c) 2014 Elsevier Ltd. All rights reserved.