Schematic of a multi-cell E-TAC process showing the cold electrolyte circulating in cell A, generating H2 gas that is phase-separated in the middle (blue) tank on the left, while the hot electrolyte circulates in cell B, generating O2 gas that is phase-separated in the red tank on the left. The intermediate-temperature wash fluid in the grey tank on the left is circulated through a bypass most of the time. This fluid is used to ‘push’ the cold and hot electrolyte solutions to their respective tanks at the end of the H2 generation or O2 generation steps.