New conceptual design and modeling of an energy storage and recovery unit

The intermittent nature of renewable energy sources is a key challenge to their integration into the electricity grid. The aim of this paper is to introduce an advanced concept of Power-to-Gas (PtG) plant, which is designed to bring a closed-loop solution able to absorb electricity surplus and to restore it later, via the transient storage of energy carriers. After a brief conceptual overview of the studied unit and its individual components, the paper proposes a steady state model that is used to assess process flowsheets as well as operating conditions of the industrial scale unit. The results indicate that during the storage phase, a 200 MW power supply to the electrolysis process leads to a corresponding 155 MW of SNG produced in a methanation process with an efficiency of 83%. The stored SNG can be burned in pure oxygen during the recovery phase to produce up to 480 MW electric power as well as CO2 rich product gas.