Deep seam and minesoil carbon sequestration potential of the South Wales Coalfield, UK

Pore Structure and Adsorption Characteristics of Maceral Groups: Insights from Centrifugal Flotation Experiment of Coals

Coal has various types of macerals, which have different pore structures and adsorption properties that change with coal's thermal metamorphism. In-depth study of the characteristics of different coal macerals, especially the pore structure and adsorption properties, can better predict the coal reservoir gas storage capacity and migration ability. In this study, the sub-samples enriched in a specific maceral group with different coal ranks and particle sizes were obtained by centrifugal flotation experiments. Then, experiments containing low-temperature N₂ isotherm adsorption (LT-N₂GA), low-temperature CO₂ isotherm adsorption (LT-CO₂GA), and methane isothermal adsorption were carried out on the sub-samples to quantitatively analyze the evolution characteristics of pore structure and adsorption properties of different maceral groups. The results showed the following: (1) The separation effect of the light maceral groups by centrifugal flotation experiments increased with the decrease of particle sizes, which were treated with the heavy liquid of low and medium densities, while that of the heavy maceral groups had the relatively best separation effect in the particle sizes of 0.1-0.125 mm, which were treated with the heavy liquid of high densities. (2) The vitrinite-enriched samples had more ultra-micropores (mainly within the diameter range of 0.4-0.65 nm), while the inertinite enriched samples had more mesopores and transition pores (mainly within the diameter range of 40-50 nm). (3) For the low-rank coal, inertinite had more potential methane adsorption capacity. However, for the medium- and high-rank coal, vitrinite had more potential methane adsorption capacity. (4) For the low-rank coal, the adsorption potential and adsorption space increased with the increase of the inertinite content, while the adsorption potential, adsorption space, and surface free energy for the medium- and high-rank coal increased with the increase of vitrinite content. It is expected that the results can deepen the understanding about the gas storage capacity and migration ability and be used in the prevention of gas outburst and the reduction of carbon emission.

The potential for carbon sequestration by afforestation can be limited in dryland river basins under the pressure of high human activity

Dryland regions cover >40 % of the Earth's land surface. Both human activities and climate change have driven forest expansion in parts of dryland regions. Afforestation has been implemented widely to enhance carbon sequestration and benefit the ecological environment of many global drylands. However, the potential and available afforestation space in drylands is uncertain due to the conflicts between additional forest areas and available water. How afforestation will affect the potential for forest carbon stock is also unclear. This paper assessed the future spatial distribution of afforestation and potential forest carbon stock in a typical dryland region, the Yellow River Basin (YRB), which has experienced rapid afforestation and high human activity pressure over the past several decades. Combining the future land use change model (FLUS) and local important development planning, we simulated future afforestation distributions and estimated potential forest carbon stock under the ecological restoration, urban expansion, and cultivated land protection scenarios. The afforestation carbon stock was predicted by considering the dynamic change trends of the mature forest, the immature forest, and new afforestation. The results demonstrated that the potential afforestation area would be limited to 4000 km² in the YRB accounting for less than one-twentieth of the total forest area. Accordingly, the maximum potential forest carbon stock would increase only 59.5 × 10⁶ t. These findings implies that afforestation programs in drylands should further consider the optimum allocation of afforestation space and the balance between carbon and water in drylands, especially under a changing climate with increasing human activities.

The effect of China's pilot carbon emissions trading schemes on poverty alleviation: A quasi-natural experiment approach

As an important new tool for ecological poverty alleviation, carbon trading compensation is combining ecological protection with rural poverty alleviation. This paper evaluates the poverty alleviation impact of China's pilot carbon emissions trading schemes (ETS) at the provincial level before and after the program, which was implemented from 2007 to 2017. Specifically, we measure poverty alleviation in terms of rural residential income growth and rural job creation. By exploiting the quasi-experimental variation in whether provinces were affected by this pilot ETS policy, our analysis finds that the ETS policy resulted in increases in rural residential income and employment. We find the estimated effects correspond to an increase of approximately 752.6 yuan in annual rural residential income and 2.35% in the ratio of rural employed population to the total employed population, accounting for 9.5% of the rural residents' income and 7.11% of the rural employment, specifically. The results imply that the implementation of ETS is beneficial to income growth and job creation for rural areas of China, which mean the ETS policy may be conducive to poverty alleviation in affected provinces.