High temperature fuel cell/electrolyzer system with energy storage media and auxiliaries outside the fuel cell power generator

A fuel cell/electrolyzer system capable of charging and discharging, with an energy storage function, comprising:

• (a) a source of fuel;
• (b) a source of electricity;
• (c) an optional reformer receiving the source of fuel and outputting a feed stream of H2O/steam;
• (d) a feed stream of H2O/steam;
• (e) an energy storage subunit which receives the feed stream and which subunit contains a metal based material which provides a metal oxide and hydrogen at discharge where the metal oxide is retained in the energy storage subunit providing hydrogen rich fuel of H2 and steam, with a volume % ratio hydrogen:
• steam of 60 to 75:25 to 40;
• (f) a thermal energy source to heat the discharged hydrogen rich H2 and steam to provide a hydrogen rich H2 and steam fuel entry stream having a temperature over about 750° C.;
• (g) a fuel cell power generator/electrolyzer that is completely separated from all other components in the system, which fuel cell power generator/electrolyzer receives the heated, hydrogen rich H2 and steam entry stream, said fuel cell power generator/electrolyzer providing energy out, depleted oxidant out and depleted H2 fuel of H2O and steam;
• and which electrolyzer will split water into H2 and O2 during charging when the electricity source is fed into the system;
• (h) an oxidant source which is passed to the fuel cell power generator/electrolyzer;
• and
• (i) separate additional storage media subunit containing a metal based material to be fed with the depleted fuel out, which metal based material will chemically charge the depleted H2 fuel of H2O and steam exiting the fuel cell power generator/electrolyzer, to provide recirculated fuel of higher H2 content plus steam which is passed to the energy storage subunit of (e);
• where at steady state operation the source of fuel (a), and optional reformer (c) can be eliminated or their output reduced.