Abstract: The embodiment relates to an energy conversion system having: a Solid Oxide Fuel Cell (SOFC) unit (A) having an anode and a cathode side, for receiving a fuel (1) and a steam of oxidant (4) and for converting a fraction of chemical power of the fuel (1) into electric power; a combustor unit (B) to receive unconverted fuel (5) and unconverted oxidant (6), configured for converting the unconverted fuel (5) and the unconverted oxidant (6) into product gas (10); an expander unit (C) to receive the product gas (10) and configured for expanding said product gas (10) into flue gas (12); a cooler unit (E) in thermal relationship with a heat sink (27) and configured for cooling said flue gas (12); a separator (F) for removing condensed species (15) from the cooled gas (14) exiting the cooler unit (E); and a first compression unit (K) for increasing the pressure of said oxidant (26, 4, 8) to a value suitable for the SOFC unit (A) and the combustor unit (B).