The Sabatier process has significant blockers to actually being used: First, it needs a source of carbon dioxide, and the small concentration of it in he atmosphere is insufficient. Biofuels could be used for this, but they aren't produced in sufficient quantities. Second, it needs a source of hydrogen. Almost all hydrogen produced today is done through steam reformation, which emits carbon dioxide. Electrolysis accounts for a slim minority of hydrogen produced today, mainly due to inefficiency and issues with electrodes corroding. Nobody is operating commercial power to gas storage facility, it's only prototypes.