Process modelling of a biogas-fed SOFC-ORC hybrid system

This work aims to develop a 0-D simulation model of an hybrid SOFC-ORC system and to estimate the benefits in terms of power production respect to the fuel cell alone. Reference case is an industrial Fuel Cell system with three modules. It is a Solid Oxide high temperature Fuel Cell working at atmospheric pressure, manufactured by the Finnish company Convion Ltd. It converts the chemical energy of a biogas flow from a Waste Water Treatment Plant into thermal and electric power up to 58 kW per module and releases gas exhausts at about 220°C. Here it is supposed to use the latter for further power production by means of compatible power cycle. The low temperature gases as a source for the secondary cycle limit the choice within organic fluid cycle systems, absorption system, Stirling engines and the less known Kalina based systems. Organic rankine cycle will be chosen according to some considerations described in the text, and performances with some among widespread organic fluids are compared.