Product-based Carbon Constraint Energy Planning with pinch analysis for sustainable methanol industry in China

For the purpose of greenhouse gas control in chemical industries, the industrial structure adjustment and lowcarbon technology retrofit are the alternatives for policymakers and plants to simultaneously meet the energy demand and carbon emission limit. Considering the various technological sources and predictable product demand in methanol production industries, this paper presents the method of Product-based Carbon Constraint Energy Planning (PCEP) combined with improved GM(1,1) model to analyse the practical interaction between energy demand and carbon emission for methanol industry in 2020 in China. The results show that without any emission reduction measures, the total carbon emissions of methanol industry in 2020 would be 4.84 times larger than that of 2011. By enhancing the methanol production of biomass routing and conducting the project of CO2 capture and storage (CCS) in all coal-to-methanol plants, the total carbon emissions would be 36.01 % less than the given carbon constraint. Besides, at least 65 % of coal-to-methanol plants should be retrofitted with CCS on the consideration of the current challenges of biofuel development in order to meet the carbon constraint. The energy structure of China and the inherent property with high carbon content in coal determine that the coal-to-methanol routing contributes the most of methanol supply but also the maximum carbon emissions in the methanol industry, even if policymakers and plants take measures to adjust the industrial structure and retrofit the existing plants with low-carbon technology.