Energy analysis of a cogeneration plant using coal gasification and solid oxide fuel cell

This paper presents a conceptualized combined heat and power (CHP) scheme based on coal gasification and with a high temperature, pressurized solid oxide fuel cell (SOFC) in the topping cycle and a bottoming steam cogeneration cycle. An energy analysis is done for this CHP plant. The study reveals that such a plant offers a substantial saving in fuel with respect to separate plants for the same power and utility heat. The total power of the plant optimizes at a pressure ratio for a given cell operating temperature. However, this optimum pressure ratio increases with higher cell operating temperatures. On the other hand, the utility heat rate decreases with the increasing pressure ratio for any cell operating temperature. In a combined effect of these utility outputs (i.e. power and utility heat), the overall performance of the plant, expressed by fuel energy savings ratio (FESR), is found to optimize at a particular pressure ratio for a given cell operating temperature. For example, the maximum FESR is found to be 30% for an optimum pressure ratio of about 18 for a cell operating temperature of 1273 K.