Method for operating of a regenerative bipolar membrane fuel cell, and regenerative bipolar membrane fuel cell there for

A method for operating a regenerative bipolar membrane fuel cell, the method comprising the steps of:

• providing a regenerative bipolar membrane fuel cell comprising:
• a reactor with an anode compartment having an anode and a cathode compartment having a cathode;
• and
• a number of cell units separating the anode and cathode compartments, wherein the cell unit comprises an anion exchange membrane, a cation exchange membrane, and a bipolar membrane, with the membranes defining compartments;
• providing a number of fluids to the cell, with at least a fluid on both sides of the bipolar membrane with ion concentrations such that the difference in water activity of the fluids on both sides of the bipolar membrane is minimized, wherein the difference in water activity of both fluids in contact with the bipolar membrane is maintained within the range of −0.015 to +0.015;
• storing energy in an energy storage state by providing an external current to the reactor such that a pH difference between fluids in contact with the bipolar membrane is achieved;
• switching between the energy storage state and an energy generation state;
• and
• regenerating energy in the energy generating state from the pH difference between fluids in contact with the bipolar membrane.