A New Power–Chemicals Cogeneration Design for Thermal Power Stations with CO₂ Capture and Utilization

Combining oxygen-enriched combustion CO₂ capture technology and CO₂ hydrogenation with methanol technology, a new power–chemicals cogeneration (PCC) design is proposed for thermal power stations with CO₂ capture and utilization under the power-to-liquid concept. For material integration, CO₂ from an oxygen-enriched thermal power station and H₂ from water electrolysis using renewable power serve as raw materials for the methanol production process. O₂ from water electrolysis using renewable power is supplied to the oxygen-enriched thermal power station; thus, electricity can be saved and investment in an air separation unit can be beneficial. For energy integration, power for gas compression and heat for methanol rectification in the methanol production process are supplied by an oxygen-enriched thermal power station. The energy released from the methanol production process is fully recovered for extra power generation. Energy analysis results show that a high CO₂ capture and utilization ratio, which is defined as the ratio of the captured and utilized CO₂ to the total CO₂ generation, of 78.1% could be achieved. By integrating the system in a 600 MW thermal power station, the net power generation and methanol production of the proposed design reaches 473.1 MW and 56.1 kg/s, respectively. Economic analysis results show that the power cost is estimated to be 62.8 $/MWh, which has great market competitiveness compared to the conventional thermal power station with CO₂ capture. Due to the saved material expense and power and heat expense, the methanol cost is reduced from 1.33 $/kg to 1.20 $/kg. The H₂ expense by water electrolysis using renewable power has a decisive influence on the methanol cost.