Clean technology investment considering synergistic effects: a case from the steel sintering process

The dual objectives of air pollutant control and carbon emission reduction highlight the importance of determining investment methods in end-of-pipe (EOP) technology to achieve cost optimization goals. This paper aims to bridge the gap between the cooperative control theory and practical applications. We propose a framework using optimal control theory to obtain a technology investment path while considering the two-way synergy effect. To verify the effectiveness of the model, we considered three typical technologies in ultra-low emission transformation of a certain steel process. The used case in the study set the emission reduction of $${\mathrm{SO}}_2$$ SO 2 , $${\mathrm{NO}}_x$$ NO x and $${\mathrm{CO}}_2$$ CO 2 as 55%, 70% and 80% compared to their basic cases, respectively. Considering the synergy effect, the peaks of the installed capacity of three technologies including carbon capture, denitrification, and desulfurization were obtained as 0.12 million tons, 5 million tons, and 15 million tons. Also, the related net emissions for the pollutant were 300, 400, and 1000 million tons. We found that terminal desulfurization and denitrification technology increase $${\mathrm{CO}}_2$$ CO 2 emissions accounting for about 2% due to the negative synergy. However, the negative emission contribution from carbon abatement technology is greater accounting for about 40%. We also found that different policy objectives and emission factors have a greater impact on the investment path. These results demonstrate that we cannot completely ignore the negative emission reduction effects when adopting these EOP technologies. It is necessary to reevaluate these negative effects to the greatest extent so as to develop a more reasonable technological path, which is a guarantee for achieving the expected emission reduction targets.