Alternative system designs of biomass gasification SOFC/GT hybrid systems

In this paper, four different systems based on integrated hybrid solid oxide fuel cell gas turbine and biomass gasification are modelled to study the influence of the gasification technology, gas cleaning technology and system scale on the overall system performance. The different gasification technologies evaluated are the atmospheric indirect steam gasification and pressurized direct air gasification. The evaluated gas cleaning technologies are low temperature gas cleaning and high temperature gas cleaning and the two scales are 100 kWe and 30 MWe. The system performances have been analysed by means of models developed with the thermodynamic flow-sheeting program Cycle-Tempo. The system alternatives are compared using the results from the different models and the exergy analysis made for each system design. The results show that the large scale system based on pressurized direct air gasification and high temperature gas cleaning has the highest electrical exergy efficiency of 49.9%. It was also found that the gasification technology has hardly any influence on the overall system performance. High temperature gas cleaning results in a slightly higher performance (0.5%) compared to low temperature gas cleaning. Large scale systems have a higher efficiency than small scale systems, due to larger exergy losses in mainly balance of plant components.