Storage and restoring the electricity of renewable energies by coupling with natural gas grid

Abstract : The renewable energy network is constantly expanding due to the increasing world demand to reduce greenhouse gases emissions and to maintain an adequate energy supply level. However, renewable energy systems are facing two major difficulties: storing electrical power when consumption is quite below the production potential, and delivering electricity when high consumption peaks appear. This paper aimed to simulate an alternative process that can store and restore renewable electricity by forming and reforming the natural gas (methane). The specificity of this process is sharply interesting, since it uses methane as a means of storage instead of electricity, taking advantage of the high energy density of methane. The gas transformation will be coupled to a reversible solid oxide cells (RSOC) working at high temperature (1073 K). The simulation results showed that the installation can deliver electricity with 36.4% of energy efficiency, while electricity storage is performed with an efficiency of 92.4%. The best advantage lies on the process carbon balance: storing then restoring 1 MWh of electricity will only emits 69 g of additional CO2 in the air.