Efficiency improvement for coal-fired power plants by H2/O2 combustion: Performance analysis and economic evaluation

The combination of energy storage and electric network is a crucial point to improve the intermittency of renewable energy, facilitating higher renewable energy utilization rate and better electric network stability. With rapid response time and high energy densities, the H2/O2 combustion is a potential solution for improving the peak shaving capacity and power generation efficiency of coal-fired power plants (CFPPs). In this paper, two integration systems based on the external hydrogen cycle are proposed: normal pressure H2/O2 combustion system (NPHC-CPFF) and high pressure H2/O2 combustion system (HPHC-CFPP). Simulation results show that compared to the original CFPP with 600 MW capacity and 42 % thermal efficiency, NPHC-CFPP and HPHC-CFPP achieve a maximum power generation of 678.7 MW and 683.2 MW, respectively, with corresponding thermal efficiencies of 46.5 % and 46 %. The H2/O2 combustion steam offers a more significant contribution to the power generation performance under lower loads, and can replace the extraction system for heating the feedwater in CFPP to some extent. The exergy analysis shows that the introduction of H2/O2 combustion will reduce the exergy efficiency of the extraction system. HPHC-CFPP with the ancillary turbine has the highest exergy efficiency of 43.2 %. When applied for peak shaving, the novel integration systems can reduce the unit load from 50 % to 24.9 % with a maximum daily revenue of 191,000 CNY.