Conceptualizing novel CH₃OH-based thermochemical energy storage routes via a modeling approach

Abstract

Thermal energy storage systems are an emerging option for efficient energy conversion and storage, especially if they can concentrate solar energy. This work studies a flexibleCH₃OH-to-CH₄ conversion system from intermediate conversion to synthesis gas. The design is based on a combination of processes already tested experimentally and applied in industry. The concept we develop integrates the decomposition of CH₃OH and methanation processes, providing different pathways for energy use, such as natural gas, direct heat, and power supply, or storage in chemical bonds. This flexibility in adapting the operation of the system to different energy availability and energy needs makes the concept appealing for changeable application. Thermal efficiencies of 39% are possible for the CH₃OH decomposition phase and of 26% for the overall system for CH₄ production. Thus, from the high energy density of CH₃OH, levelized storage costs of €134.8/MWh can be obtained, which is lower than systems based on molten salts. These results should spur interest in further advances for the proposed flexible concept.