Energy and exergy analyses of an integrated underground coal gasification with SOFC fuel cell system for multigeneration including hydrogen production

A novel integrated system, including underground coal gasification (UCG), steam assisted gravity drainage (SAGD) based oil sands, syngas fueled Solid Oxide Fuel Cell (SOFC), integrated gasification combined cycle (IGCC) and an electrolyzer, for hydrogen production is proposed and analyzed for practical applications, especially for Alberta region in which there are huge capacity of oil sands and coal reserves. This combined multi generation system produces syngas from underground coal without mining, produced syngas is utilized for generating electricity from IGCC and SOFC. A part of generated electricity in the Rankine cycle is used for hydrogen production through an electrolyzer. The excess steam in IGCC is utilized for SAGD process in order to extract Bitumen from underground as in-situ extraction. Energy and exergy analyses are conducted to assess the performance of the cycle, and the effects of various system parameters on energy and exergy efficiencies of the overall system and its subsystems are studied comparatively. The overall energy and exergy efficiencies of the system are found as 29.2% and 26% respectively for 20 kg/s coal feed rate. Furthermore, the effects of varying ambient temperature and pressure, syngas temperature, coal and syngas lower heating value, air and steam injection rates on the system performance are investigated.