Performance and Cost Analysis of the Hybrid Coal IGCC Systems Utilizing Biomass Fuel

Abstract

We proposed two types of the hybrid coal integrated gasification combined cycle (IGCC) systems utilizing biomass fuel; the diluted type with a biomass combustion boiler and the gasification one with biomass gasification. Both systems have a superior feature to capture CO₂ gas by low auxiliary load. These hybrid systems have also unique characteristics to make the function of electricity storage possible because most of liquid oxygen is able to be produced during nighttime and is uniformly supplied to a combustion turbine. We developed a new method to evaluate the corresponding thermal efficiency contributed by biomass by means of exergy concept. The net generating efficiency and corresponding efficiency contributed by biomass of the diluted type were estimated to be 37.5 % and 43.3 %, higher than 33.3 % and 35.0 % of the gasification one. The CO₂ capture costs of the hybrid plants were lower than that of IGCC/CO₂ capture power plant with the chemical absorption process of CO₂ capture. It was found that the electricity storage function to produce the liquid oxygen during nighttime contributes to improve the electric power generating cost in the hybrid systems.