From Process to Grid: Life-Cycle Carbon Footprint of Bio-e-methanol and Regionally Differentiated Power Mix Pathways Towards Carbon Intensity Targets in China

Based on actual operational data from a methanol production enterprise in China, this study conducts a cradle-to-gate life-cycle carbon footprint assessment of bio-e-methanol. The carbon emission contributions of each process stage are systematically quantified and further extended to China’s seven regional power grids to evaluate their capability to meet China’s Grade A/B/C standards and the EU RED II carbon intensity thresholds under current power mixes. The results show that under the baseline scenario using the Chinese public power grid and coal-derived steam, electricity consumption is the largest contributor (76.6%) of the carbon footprint of bio-e-methanol, followed by steam (22.6%). The combined strategy of “ low-carbon electricity + biomass-derived steam” is critical for deep decarbonisation. Regional analysis reveals that the Southwest China grid, with its uniquely high low-carbon electricity share of 71%, can meet the Grade C standard without any adjustment, and the Grade A, B and EU RED II standards with only minor adjustments to its power mix. All other regions require varying degrees of low-carbon electricity penetration increases. Residual power composition is the dominant factor determining compliance requirements for carbon threshold, far outweighing regional differences in current low-carbon electricity shares. This study provides a quantitative basis for methanol producers in different regions of China to optimise their power structures and devise differentiated low-carbon transition pathways.