Studies on pathways to carbon neutrality for indirect coal liquefaction in China

The production capacity of indirect coal liquefaction (ICL) in use in China has reached a level of 8 million t/a, which corresponds to a carbon footprint of >60 million t/a. ICL is facing mountainous pressure to reduce its carbon emissions when its development is planned with carbon neutrality as a background objective. This paper studies the pathways that can lead to carbon neutrality for ICL in China, constructing four carbon-neutral pathways for ICL systems with the introduction of green hydrogen, biomass as feedstock and with CCS (carbon capture and storage), which can reduce significant carbon emissions from coal-gasification and water–gas shift processes. The carbon-neutral biomass is used to replace some coal as co-feed to gasification and combustion, leading to reduced carbon emissions as well. Calculations and economic analyses are performed on different carbon-reduction pathways using a carbon-neutral ICL system on a 1 million t/a scale as an example. The results are that the pathway of direct coal substitution with biomass is the lowest carbon-reduction route at RMB 31~125/t CO2, substitution with green hydrogen costs the highest at RMB 84~422/t CO2 and CCS costs are in the middle at RMB 96~148/t CO2. Each pathway has its pros and cons, and a combination of the three may be used for the best outcome. Furthermore, a comprehensive study and systematic summation of the critical technological processes and their underlying challenges for carbon-neutral ICL together with direction for a technological breakthrough are presented. These ICL carbon-reduction pathways presented in this paper are capable of realizing an integrated development between fossil and renewable energy sources, helping the carbon-intense coal-chemical industries to achieve their goals of carbon peak and carbon neutrality.