DualFlow develops a radically new energy conversion and storage concept that combines water electrolysis, battery storage and coproduction of decarbonized chemicals into one single hybrid technology using water soluble redox mediators as energy transfer vectors. The system can be operated for electricity storage or for energy conversion to hydrogen and value added chemicals. During energy storage operation, the system works as a conventional stationary flow battery. The energy conversion starts when the battery is full but there is abundant inexpensive green electricity available. Now the battery is chemically discharged in a mediated electrolysis to produce hydrogen and value added chemicals. The energy conversion is realized by pumping charged battery electrolytes through reactors. For hydrogen production, reactor is filled with catalytic particles to catalyze electron transfer and hydrogen evolution. For value added chemical production the reactor consists of biphasic system where charged electrolyte oxidizes chemicals in an organic phase. The reaction products are then extracted into the organic phase. The energy conversion operation requires only reactors and catalyst for hydrogen evolution, indicating that the additive costs of the dual circuit is minimal. The concept results in flexible system capable of both energy storage and energy conversion to hydrogen. We strongly believe that this concept offers possibilities to produce inexpensive hydrogen, in a flexible manner without utilizing any critical raw materials.