An apparatus including at least one electrochemical flow cell in which the electrochemical flow cell includes an anode electrode, a cathode electrode and a reaction zone between the anode and the cathode. The electrochemical flow cell also includes an electrolyte storage reservoir configured to hold a molten salt electrolyte and a gas generated during charging of the at least one electrochemical flow cell and at least one conduit configured to supply the molten salt electrolyte and the gas from the storage reservoir to the at least one electrochemical flow cell. The electrochemical flow cell also includes at least one pump configured to pump the molten salt electrolyte from the storage reservoir to the reaction zone.