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Summary A growing number of governments are pledging to achieve net-zero greenhouse gas emissions by mid-century. Despite such ambitions, realized emissions reductions continue to fall alarmingly short of modeled energy transition pathways for achieving net-zero. This gap is largely a result of the difficulty of realistically modeling all the techno-economic and sociopolitical capabilities that are required to deliver actual emissions reductions. This limitation of models suggests the need for an energy-systems analytical framework that goes well beyond energy-system modeling in order to close the gap between ambition and reality. Toward that end, we propose the Emissions-Sustainability-Governance-Operation (ESGO) framework for structured assessment and transparent communication of national capabilities and realization. We illustrate the critical role of energy modeling in ESGO using recent net-zero modeling studies for the world's two largest emitters, China and the United States. This illustration leads to recommendations for improvements to energy-system modeling to enable more productive ESGO implementation.

The low-carbon development of China’s iron and steel industry (ISI) is important but challenging work for the attainment of China’s carbon neutrality by 2060. However, most previous studies related to the low-carbon development of China’s ISI are fragmented from different views such as production-side mitigation, demand-side mitigation, or mitigation technologies. Additionally, there is still a lack of a comprehensive overview of the long-term pathway to the low-carbon development of China’s ISI. To respond to this gap and to contribute to better guide policymaking in China, this paper conducted a timely and comprehensive review following the technology roadmap framework covering the status quo, future vision, and key actions of the low-carbon development of the world and China’s ISI. First, this paper provides an overview of the technology roadmap of low-carbon development around the main steel production countries in the world. Second, the potential for key decarbonization actions available for China’s ISI are evaluated in detail. Third, policy and research recommendations are put forward for the future low-carbon development of China’s ISI. Through this comprehensive review, four key actions can be applied to the low-carbon development of China’s ISI: improving energy efficiency, shifting to Scrap/EAF route, promoting material efficiency strategy, and deploying radical innovation technologies.

To systematically analyze energy-related carbon emissions from the perspective of comprehensive energy flow and allocate emissions responsibility, we introduce energy allocation analysis to carbon flow process based on Sankey diagrams. Then, to quantitatively compare different diagrams and evaluate the structural changes of carbon flow, we define changes from three dimensions including total amount change, relative growth rate and occupation ratio change (TRO), propose TRO index. The method is applied to China’s case study from 2005 to 2015. We map China’s energy-related carbon flow Sankey diagrams with high technical resolution from energy sources, intermediate conversion, end-use devices, passive systems to final services, and conduct TRO index decomposition by stages. The results indicate that in energy sources, the emission share of coal has declined due to energy transition although coal is still the largest contributor to China’s energy-related carbon emissions. In passive systems, the factory passive systems are the largest contributors, among them, emission reduction should focus on the steel, non-ferrous and chemical industries; the building passive systems should pay attention to household appliances; the vehicle passive systems should focus on cars. In final services, the demand for structural materials is the strongest driving force for carbon emissions growth.

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