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Coal seam with low permeability is widely distributed in China. Injection of flue gas (N2:CO2 = 0.85:0.15) is an effective approach to improve coal seam gas drainage efficiency. This process relates complex responses among ternary gases (CH4, CO2, and N2) competitive sorption on coals, gas diffusion, gas‐water migration by means of two‐phase flow, and coal deformation. In this paper, an improved hydraulic‐mechanical model coupling above interactions is established for flue gas injection enhanced gas drainage. This model is used to simulate flue gas enhanced drainage by finite element method. The sensitivity analyses of key factors are made to recovery a better understanding on the processes controlling flue gas enhanced drainage. Results show that the flue gas enhanced drainage can indeed improve the efficiency of gas extraction and reduce the gas pressure to the required value in a shorter duration. Due to the competitive adsorption and gas sweeping effect of injected flue gas, CH4 is driven toward drainage borehole, and CH4 pressure and content near the injection borehole decrease faster than that near the drainage borehole. The peak CH4 pressure laterally moves from the injection borehole to the drainage borehole. Higher injection pressure, initial permeability, and smaller sorption affinity ratios may lead to greater CH4 production rate at early drainage stage, but smaller CH4 production rate at late stage. The factors controlling the behavior of flue gas enhanced drainage are initial permeability, injection pressure, and sorption affinity ratios in order. This work offers useful framework to investigate important technical challenges associated with enhanced mine gas drainage, as well as unconventional gas development. [ABSTRACT FROM AUTHOR]

Taking advantage of the electrification strategy, Northwest China has made full use of its natural resources endowment, to develop renewable energy as the substitution of thermal power. To evaluate carbon dioxide (CO2) emissions from electric power sector, an extended Kaya identity equation and the Logarithmic mean Divisia index decomposition method are applied to Northwest China from 1998 to 2017. Six explaining factors are analyzed, including carbon intensity, energy mixes, generating efficiency, electrification, economy and population. The results show that driving forces of CO2 emissions from electricity system varied greatly among provinces. Generally, economic growth has mainly contributed to increase CO2 emission, while the improvement in the power‐generating efficiency has crucially decreased CO2 emission. In 2017, Promoting electrification directly increased CO2 emissions from electric system, but indirectly reduced CO2 emissions from the whole region by 5.10% through the estimation of a clean development mechanism method. Therefore, local governments are suggested continuing to promote electrification to guide future emission reduction, while enterprises and individuals need to make their own contributions to low‐carbon development. Recommendations for Resource Managers:Variations of carbon dioxide (CO2) emissions of all five provinces in Northwest China are analyzed.Logarithmic mean Divisia index analysis is used to study the main drivers of CO2 emission change.Improvements in the generating efficiency significantly reduced CO2 emissions.Due to electrification effects, CO2 emissions from electric power increased, but CO2 emissions from the region decreased.Economy effects were still the biggest drivers affecting CO2 emission. [ABSTRACT FROM AUTHOR]

Mankind is constantly pursuing economic growth and social development, and while these bring convenience to people, they involve large amounts of greenhouse gas emissions under the heavy use of energy, which produces quite serious air pollution, which not only affects people's health but also leads to ecological environmental damage. Nowadays, the impact of the environment and the negative impacts of the world's economies while promoting economic growth are the most important issues for economies to achieve balanced development. This study uses the dynamic slack‐based data envelopment analysis (DEA) model to assess the environmental energy efficiency of high‐income economies (including China) and explore the negative impacts on the environment, to obtain a basis for energy‐saving emission reduction methods or configurations by using 48 high‐income economies (including China) from 2010 to 2014. The interperiod (carryover) variable is gross domestic product (GDP). The empirical results show that economies with high energy efficiency have a large consumption of energy and are unable to reduce carbon dioxide emissions. We also find that there exists a difference in the results depending on whether GDP is considered as the carryover variable. European economies are more efficient in energy consumption than others, and Asian economies are the most inefficient. In order to pursue GDP growth, economies need to consider reducing their energy consumption and CO2 emissions and improve their energy usage efficiency, further implementing sustainability. [ABSTRACT FROM AUTHOR]

In the 2000s, the rapid growth of CO2 emitted in the production of exports from developing to developed countries, in which China accounted for the dominant share, led to concerns that climate polices had been undermined by international trade. Arguments on 'carbon leakage' and 'competitiveness'-which led to the refusal of the U.S. to ratify the Kyoto Protocol-put pressure on developing countries, especially China, to limit their emissions with Border Carbon Adjustments used as one threat. After strong growth in the early 2000s, emissions exported from developing to developed countries plateaued and could have even decreased since 2007. These changes were mainly due to China: In 2002-2007, China's exported emissions grew by 827 MtCO2, amounting to almost all the 892 MtCO2 total increase in emissions exported from developing to developed countries, while in 2007-2012, emissions exported from China decreased by 229 MtCO2, contributing to the total decrease of 172 MtCO2 exported from developing to developed countries. We apply Structural Decomposition Analysis to find that, in addition to the diminishing effects of the global financial crisis, the slowdown and eventual plateau was largely explained by several potentially permanent changes in China: Decline in export volume growth, improvements in CO2 intensity, and changes in production structure and the mix of exported products. We argue that growth in China's exported emissions will not return to the high levels during the 2000s, therefore the arguments for climate polices focused on embodied emissions such as Border Carbon Adjustments are now weakened. Plain Language Summary In the 2000s, CO2 emissions from production in developed countries flattened while emissions from their consumption grew. The rapid growth of exported emissions from developing countries to developed countries, with the largest contribution from China, played a significant role. This led to concerns that climate polices had been undermined by rapid growth in international trade. Since around 2007, growth in these exported emissions has plateaued, predominantly due to changes in China. Our study investigates China's changes, demonstrating that in addition to the effects of global financial crisis, China implemented potentially permanent structural changes. We argue that China's exported emissions are unlikely to return to the growth levels from the 2000s, and therefore trade-related climate polices will be much less relevant. [ABSTRACT FROM AUTHOR]