Carbon emission reduction accounting method for a CCUS-EOR project

It is difficult to quantify and certify the greenhouse gas(GHG)emission reduction in the entire process of a project of carbon capture,utilization and storage(CCUS)-enhanced oil recovery(EOR).Under the methodological framework for GHG voluntary emission reduction project,the carbon emission reduction accounting method for CCUS-EOR project was established after examining the accounting boundaries in process links,the baseline emission and project emission accounting methods,and the emission and leakage quantification and prediction models,in order to provide a certification basis for the quantification of GHG emission reduction in the CCUS-EOR project.Based on the data of energy consumption,emission and leakage monitoring of the CCUS-EOR industrial demonstration project in Jilin Oilfield,the net emission reduction efficiency is determined to be about 91.1%at the current storage efficiency of 80%.The accounting and prediction of carbon emission reduction for CCUS-EOR projects with different concentrations and scales indicate that within the project accounting boundary,the certified net emission reduction efficiency of the low-concentration gas source CCUS-EOR projects represented by coal-fired power plants is about 37.1%,and the certified net emission reduction efficiency of the high-concentration gas source CCUS-EOR projects represented by natural gas hydrogen production is about 88.9%.The proposed method is applicable to the carbon emission reduction accounting for CCUS-EOR projects under multiple baseline scenarios during the certification period,which can provide decision-making basis for the planning and deployment of CCUS-EOR projects.

Effects of different nitrogen fertilizer management practices on wheat yields and N_2O emissions from wheat fields in North China

Nitrogen（N） is one of the macronutrients required for plant growth, and reasonable application of N fertilizers can increase crop yields and improve their quality. However, excessive application of N fertilizers will decrease N use efficiency and also lead to increases in N2O emissions from agricultural soils and many other environmental issues. Research on the effects of different N fertilizer management practices on wheat yields and N2O emissions will assist the selection of effective N management measures which enable achieving high wheat yields while reducing N2O emissions. To investigate the effects of different N management practices on wheat yields and soil N2O emissions, we conducted field trials with 5 treatments of no N fertilizer（CK）, farmers common N rate（AN）, optimal N rate（ON）, 20% reduction in optimal rate＋dicyandiamide（ON80%＋DCD）, 20% reduction in optimal rate＋nano-carbon（ON80%＋NC）. The static closed chamber gas chromatography method was used to monitor N2O emissions during the wheat growing season. The results showed that there were obvious seasonal characteristics of N2O emissions under each treatment and N2O emissions were mainly concentrated in the sowing-greening stage, accounting for 54.6–68.2% of the overall emissions. Compared with AN, N2O emissions were decreased by 23.1, 45.4 and 33.7%, respectively, under ON, ON80%＋DCD and ON80%＋NC, and emission factors were declined by 22.2, 66.7 and 33.3%, respectively. Wheat yield was increased significantly under ON80%＋DCD and ON80%＋NC by 12.3 and 11.9%, respectively, relative to AN while there was no significant change in yield in the ON treatment. Compared with ON, overall N2O emissions were decreased by 29.1 and 13.9% while wheat yields improved by 18.3 and 17.9% under ON80%＋DCD and ON80%＋NC, respectively. We therefore recommend that ON80%＋DCD and ON80%＋NC be referred as effective N management practices increasing yields while mitigating emissions.

A representative CO_(2) emissions pathway for China toward carbon neutrality under the Paris Agreement's 2℃target

In 2021,China updated its nationally determined contributions(NDCs)under the Paris Agreement,which prompts a more accurate mea-surement of its emissions inventory and a reasonable pathway toward carbon neutrality by 2060.This study reviews the estimates using the bottom-up emissions factor method or the top-down atmospheric CO_(2) concentration inversion method to derive China's CO_(2) emissions inventory and finds that CO_(2) emissions from energy combustion and industrial processes in Chinese mainland range from 11.3-12.0 GtCO_(2) in 2021.Based on a comprehensive review of pathways proposed by domestic and international studies and an analysis of the origins of their differences,we proposed the Tsinghua-CMA pathway that coordinates the 2℃global temperature rise control target with China's current CO_(2) emissions status and mitigation policies.The pathway requires China's CO_(2) emissions to peak around 2028-2029 at about 12.8 GtCO_(2),then decline steadily to about 11.2 GtCO_(2) in 2035,3.6 GtCO_(2) in 2050,and 0.9 GtCO_(2) in 2060.Compared to a reference scenario without updated NDCs,this pathway would result in an economic cost of about 0.9%cumulative GDP between 2020 and 2060,only 1/4-1/3 of the cost associated with pathways that align with the 1.5℃target.We recommended that China improves emissions accounting by cross-validating bottom-up and top-down approaches and regularly updating the pathway toward carbon neutrality while maintaining consistency with its evolving CO_(2) emissions inventory,policy trends,and global CO_(2) emission budget updates.

Multi-regional input-output analysis for China＇s regional CH4 emissions

China is the largest CH4 emitter in the world. Given the importance of CH4 in greenhouse gas emission inventories, the characteristics ofChina＇s CH4 emissions at different scales deserve to be fully understood. Presented in this paper is an interprovincial input output embodi- ment analysis of China＇s regional CH4 emissions in 2007, based on the most recently available multi-regional input- output table, and relevant CH4 emissions data. The results show that the eastern, central and western areas contribute to 48.2%, 28.6%, and 23.3% of the national total embodied emissions, respectively. Guangdong has the highest level of embodied CH4 emissions among all of the 30 regions. The Agriculture sector produces the most embodied CH4 emissions in final demand, followed by the Construction, Food Production and Tobacco Processing, and Other Service Activities sectors. Significant net transfers of embodied CH4 emission flows are identified from the central and western areas to the eastern area via interregional trade. Shanxi is the largest interregional exporter of embodied CH4 emissions. In contrast, Guangdong is the largest interregional importer. Energy activities, agricultural activities, and waste management comprise 65.6%, 30.7%, and 3.7% of the total embodied CH4 emissions in interregional trade, respectively. By using consumption-based accounting principles, the emis- sion magnitudes, per capita emissions, and emission intensities of most eastern regions increase remarkably, while those of some central and western regions decrease largely. To achieve regional CH4 emission mitigation, comprehensive mitigation measures should be designed under consideration of regional transfer of emission responsibility.

A Brief Account of Domestic Vehicle Diesel Engines and Their Emission Control

Ⅰ. Briefing domestic vehicle diesel engines Before the 1970s, domestic vehicle diesel engines were mainly applied to heavy vehicles, while medium and light vehicles were powered chiefly with gasoline engines.