A thermodynamic analysis of a solar hybrid coal-based direct-fired supercritical carbon dioxide power cycle

Efficient utilization of coal for power generation with carbon capture as well as development of solar hybrid system are being aggressively researched currently. To advance the utilization of solar energy and achieve zero emission for coal-based power generation more efficiently, a novel direct-fired, oxy-combustion supercritical carbon dioxide power cycle integrated with the solar-driven coal gasification was proposed. In the proposed system, the concentrated solar energy is utilized for coal gasification, and then the produced syngas is combusted with high-purity oxygen to drive a semi-closed supercritical carbon dioxide power cycle with intensive heat recuperation and near-zero carbon emission. Detailed analytical models based on energy and material balance were developed and the overall system thermodynamic performance were determined by the process simulation. Results showed that, at the designate point, the proposed system can save 29.9% of coal consumption and the net system energy efficiency and exergy efficiency soar to 43.4% and 44.6%, respectively; and the annualized coal saving can reach 10.46 kilo tonnes with the annual solar-to-electricity efficiency at 16.9%. The proposed concept may provide a new approach to advancing solar-coal hybridization power generation with near-zero emission.