Proposal and thermodynamic analysis of a novel oxy-methanol combustion gas turbine combined cycle with zero emission

Green methanol, produced from renewable energy sources, holds substantial potential for power generation. To explore the thermodynamic performance of methanol as a power fuel with zero emission, a novel oxy-methanol combustion gas turbine combined cycle (GTCC) is proposed. Different from the conventional GTCC, the O₂, a byproduct in green methanol production, is utilized for methanol combustion and the mixture, mainly consisting of CO₂ and H₂O, is recycled as the working fluid instead of air. Thus, zero carbon emission can be realized as the high-concentration CO₂ is directly split from the cycle cold-end for the carbon capture and storage (CCS). Detailed energy and exergy analyses are conducted and the overall system thermodynamic performance is discussed under different operating conditions. Results demonstrate that the net efficiency of the basic system is 60.73 %, featuring an efficiency penalty of only 2.91 % points for CCS. Exergy analysis reveals that the exergy efficiency is 57.78 %, higher than that of the reference system without CCS (56.57 %) as CO₂ captured is also considered as a product. Furthermore, increasing the pressure ratio could effectively enhance the system efficiency. At the optimal pressure ratio of 50, the net energy/exergy efficiency further ascends to 61.94 %/58.85 %. The proposed concept might offer a science and technology foundation for developing efficient oxy-methanol combustion GTCC with zero carbon emission.