A fuel cell system comprising: at least one high temperature fuel cell stack having an anode side and a cathode side and configured to generate electrical power; an exhaust recuperator configured to cool anode exhaust output from the anode side of the at least one fuel cell stack , and to pre-heat an input oxidant gas using heat in the anode exhaust; a heat exchanger configured to receive the pre-heated input oxidant gas from the exhaust recuperator and to receive cathode exhaust from the cathode side of the at least one high temperature fuel cell stack , and further pre-heat the input oxidant gas using heat in the cathode exhaust output from the cathode side of the at least one high temperature fuel cell stack ; and an anode gas oxidizer /high level heat recovery assembly comprising: an anode gas oxidizer configured to oxidize anode gas received from the exhaust recuperator using the input oxidant gas received from the heat exchanger , and to output high temperature oxidant gas at a temperature in a range of 537.78 to 1093.33°C (1000 to 2000°F); and a high level heat recovery system configured to receive the high temperature oxidant gas from the anode gas oxidizer , to recover high level heat from the high temperature oxidant gas, and to output high temperature oxidant gas to the cathode side of the at least one high temperature fuel cell stack . at least one high temperature fuel cell stack having an anode side and a cathode side and configured to generate electrical power; an exhaust recuperator configured to cool anode exhaust output from the anode side of the at least one fuel cell stack , and to pre-heat an input oxidant gas using heat in the anode exhaust; a heat exchanger configured to receive the pre-heated input oxidant gas from the exhaust recuperator and to receive cathode exhaust from the cathode side of the at least one high temperature fuel cell stack , and further pre-heat the input oxidant gas using heat in the cathode exhaust output from the cathode side of the at least one high temperature fuel cell stack ; and an anode gas oxidizer /high level heat recovery assembly comprising: an anode gas oxidizer configured to oxidize anode gas received from the exhaust recuperator using the input oxidant gas received from the heat exchanger , and to output high temperature oxidant gas at a temperature in a range of 537.78 to 1093.33°C (1000 to 2000°F); and a high level heat recovery system configured to receive the high temperature oxidant gas from the anode gas oxidizer , to recover high level heat from the high temperature oxidant gas, and to output high temperature oxidant gas to the cathode side of the at least one high temperature fuel cell stack . an anode gas oxidizer configured to oxidize anode gas received from the exhaust recuperator using the input oxidant gas received from the heat exchanger , and to output high temperature oxidant gas at a temperature in a range of 537.78 to 1093.33°C (1000 to 2000°F); and a high level heat recovery system configured to receive the high temperature oxidant gas from the anode gas oxidizer , to recover high level heat from the high temperature oxidant gas, and to output high temperature oxidant gas to the cathode side of the at least one high temperature fuel cell stack . <EOS>