Near-zero CO2 emissions power plant based on high temperature fuel cells

The recent awareness on the environmental issues related to global warming is leading to the search for always more efficient energy conversion systems and, mainly, with very low carbon dioxide emissions. In fact, they are strictly related to the combustion reaction of fossil fuels which is the main process of the actual power generation technology. In this regard, fuel cells are energy conversion systems which are characterized by higher efficiency and near-zero CO2 emissions. Their novel integration with conventional power plants participates to the concept of the decarbonization of the economy, In this work, the integration of two high temperature fuel cells (HTFC) with a gas turbine power plant has been proposed and investigated, thanks to the combination of a physical model of the fuel cells and a numerical one of the components involved in the gas turbine cycle. In the layout studied, fresh air is compressed, pre-heated and used in a Solid Oxide Fuel Cell (SOFC), where the high operating temperature and the exothermic process give exhaust gases at very high temperatures, suitable for an expansion in a turbine. After the expansion, the gases are rich of CO2 and, so, they can be sent to the cathode side of a Molten Carbonate Fuel Cell (MCFC). Hence, the so-defined integrated plant is composed by three power units: a turbine, a SOFC and a MCFC; operating pressure, fuel need, oxygen and carbon dioxide utilizations in the fuel cells are parameterized in order to optimize the whole plant and find additional room of energy exploitation. Moreover, the MCFC acts as an active device for carbon separation, introducing further environmental benefits.