The green and low-carbon transformation of the iron and steel industry stands as a pivotal cornerstone in the development of China. It is an inevitable trajectory guiding the future of industry. This study examined the energy consumption and carbon emission trends in the iron and steel industry. Variations under different scenarios were analyzed while emphasizing production control, changes in production structure and energy efficiency improvement. The analysis integrated the extreme energy efficiency model. This study proposed methods to enhance energy efficiency in the iron and steel industry. The costs of energy efficiency improvement and production structure changes were assessed using marginal energy saving and abatement cost curves. The findings showed that the carbon emission reduction contribution of crude steel production decline is the highest, while energy efficiency improvement technology offers the smallest, whose contribution, however, is substantial and cannot be overlooked by 2030. Energy efficiency improvement in the Chinese iron and steel industry results in an average unit energy saving and abatement cost of 27.0 yuan. It results in a total abatement cost of 21.02 billion yuan and a potential abatement of 780 Mt. Considering abatement potential, altering production structure offers significantly higher cumulative abatement compared to energy efficiency improvement technology. This is because the per unit abatement cost of production structure change is 702.7 yuan. However, this high cost poses a challenge to widespread adoption. The integration of the iron and steel industry into the carbon trading system necessitates reinforcing market constraints and expediting process adjustments. These steps are crucial to achieving the green and low-carbon transformation of the industry.

The iron and steel industry is the leading industry supporting China’s industrial sector. Currently, there is less assessment work on green and low-carbon technologies for the iron and steel industry. This study clarifies the overall strategy of technology assessment by researching the relevant theories and methods of technology assessment. The study further establishes a scientific and reasonable comprehensive assessment index system of green and low-carbon technologies for the iron and steel industry from the aspects of technology index, economy and promotion, and application, including factors such as 11 indexes, the amount of energy saving, carbon dioxide emission reduction, and the resource recovery rate by utilising analytical and comprehensive methods and combining with the characteristics of the technologies. By analysing and comparing the advantages and disadvantages of the commonly used assessment methods, the entropy weighting method, grey correlation analysis method, and TOPSIS (technique for order preference by similarity to an ideal solution) method are combined and optimised to construct a comprehensive assessment model. The Latin hypercube sampling method is also introduced to analyse the technical parameters in combination with the evaluation model. Finally, fourteen iron and steel green and low-carbon technologies were selected for case assessment and uncertainty analysis of technical parameters, and it was found that the comprehensive assessment result of gas combined cycle power generation technology was optimal. After determining the weights of each assessment indicator through the entropy weighting method, it is concluded that the technical performance indicator > economic indicator > promotional indicator. A comparative analysis of the results under the three preference decisions concludes that technical performance is the main obstacle to improving the comprehensive assessment score of the technology, followed by the economics of the technology. Finally, the uncertainty analysis of the technical parameters shows that the fluctuation of the technical parameters not only affects the performance of the technology, but also affects the weights of the indicators and the comprehensive evaluation results of the technology.