Driven by the search for the highest theoretical efficiency, in the latest years several studies investigated
the integration of high temperature fuel cells in natural gas fired power plants, where fuel cells are
integrated with simple or modified Brayton cycles and/or with additional bottoming cycles, and CO2 can
be separated via chemical or physical separation, oxy-combustion and cryogenic methods. Focusing on
Solid Oxide Fuel Cells (SOFC) and following a comprehensive review and analysis of possible plant
configurations, this work investigates their theoretical potential efficiency and proposes two ultra-high
efficiency plant configurations based on advanced intermediate-temperature SOFCs integrated with a
steam turbine or gas turbine cycle. The SOFC works at atmospheric or pressurized conditions and the
resulting power plant exceeds 78% LHV efficiency without CO2 capture (as discussed in part A of the
work) and 70% LHV efficiency with substantial CO2 capture (part B). The power plants are simulated at
the 100 MW scale with a complete set of realistic assumptions about fuel cell (FC) performance, plant
components and auxiliaries, presenting detailed energy and material balances together with a second
law analysis.