Low-carbon roadmap of chemical production: A case study of ethylene in China

Column: Research    Tag: Life cycle assessment

The increasing emissions of carbon dioxide (CO2) are primarily driven by the rapid expansion of energy-intensive sectors such as the chemical industry. This work selects ethylene, one of the most important chemicals, as a model study to represent the low-carbon roadmap of chemical production. Four strategies improving the efficiency of fossil resource usage, developing the technology for carbon capture and storage (CCS), CO2 chemical conversion, and converting biomass resources into chemicals, are used to reduce CO2 emissions. A comprehensive analysis of the life cycle CO2 emissions of different ethylene production routes has been performed to compare their emission reduction potential. The results indicate that the BMTO (biomass to olefins via methanol-to-olefins) pathway releases the least CO2 (− 1.3 t CO2/t ethylene), while the CFTO (coal to olefins via Fischer-Tropsch synthesis) possesses the highest CO2 emissions. Combining CCS with BMTO results in CO2 emissions of – 8.2 t per t ethylene. Furthermore, we analysed the annual production and CO2 emissions of ethylene in the last 17 years and integrated this real-time change with different pathways. The CO2 emissions have decreased by 29.4% per t ethylene from 2000 to 2016 in China. However, the total amount of CO2 emissions continuously increases in ethylene production industry. Given that China has promised to hit peak CO2 emissions by 2030, a scenario analysis was performed. To achieve this goal, the ratios of BMTO, CO2MTO (CO2 to olefins via methanol-to-olefins) or BETE (ethanol to ethylene pathway originating from biomass) pathways should increase by 1.0%, 1.2% and 1.1% annually from 2020, respectively. Then more than 500 million metric tons of CO2 will be eliminated from 2020 to 2040. The results highlight the pivotal role that regulation and policy administration can play in controlling CO2 emissions by increasing average technological level and turning to low-carbon routes in the chemical industry in China.