Managing Methane Emissions in Abandoned Coal Mines: Comparison of Different Recovery Technologies by Integrating Techno-Economic Analysis and Life-Cycle Assessment.

Methane emissions from worldwide increasing abandoned coal mines have posed multiple challenges of global warming, energy waste, and explosion risk. This study first profiles the dynamic patterns of coal mine methane emissions in different recovery technologies, methane extraction with drainage (MEWD, mine-water concurrently extracted and treated) and direct methane extraction (DME, noncontrol on mine-water), in two abandoned mines from Ningxia and Inner Mongolia as China's leading coal provinces. Then, we conducted a techno-economic analysis and life-cycle assessment to quantify their comprehensive benefits. The key findings are as follows: (1) MEWD can long recover methane, although the economic profits decrease with declining methane extraction volume. DME can only work for ∼5 years, after which the mine is flooded, where methane is sealed underground and not recoverable. (2) MEWD drains and further treats the mine-water with an additional 29.4-35.9 million CNY cost compared with DME, while MEWD can achieve greater life-cycle environmental benefits with more cumulative methane recovery, whose CO2-eq (GWP-100) and SO2 reductions are 64.4 and 53.4% higher than those of DME. (3) MEWD is more promising for large-scale implementation, where feed-in tariffs and carbon market measures can improve the economics for sustainable management of incremental abandoned mine methane.

Road freight emission in China: From supply chain perspective.

Freight emissions management has entered the deep-water zone. This study evaluated road freight emissions from supply chain perspective using China's 2007, 2010 and 2012 multiregional input-output table. For the first time, we quantified road freight emission based on sectors in China. Heavy industries, mining, agriculture and light industry contributed 71%,14%, 12% and 3% of total NOx emissions in 2012 from production perspective. Construction was the largest consumption sector (43%) responsible for road freight emission from consumption perspective. Upstream transport and final product transport emitted 3.04 Tg (80%) and 0.77 Tg (20%) NOx in 2012. Huge disparities of road freight emissions flows and allocation patterns were found across provinces in China in terms of resource endowments, geographical position and economic development. The road freight emission increased rapidly from 2007 to 2012, and economic growth effect outpaced emission control effect caused by emission standard upgrade and thus dominated the emission growth. The production structure and consumption pattern changes also promoted the emission growth. It is thus important to mitigate freight emissions with different strategies based on a certain sector's freight emissions features from the whole supply chain.

The impact of marine shipping and its DECA control on air quality in the Pearl River Delta, China.

Marine trade has significantly expanded over the past decades aiding to the economic development of the maritime countries, yet, this has been associated with a considerable increase in pollution emission from shipping operation. This study aims at considering both sides of the spectrum at the same time, which is including both public and shipping business. Of the key significance would be to optimize the operation of the shipping industry, such that its impact on air pollution is minimized, without, however, significant escalation of its cost, and therefore to protect the whole seaborne trade. To do this, we considered the impacts of three control strategies, including the current emission control area (ECA) design, as well two additional ones. Thus the first scenario (DECA1) was based on the China's domestic emission control area (DECA), which was set up in 2016. The DECA1 scale was only 12 nautical miles, which was much smaller than the emission control areas in US or Europe. We defined the second scenario (DECA2), by stretching the zone to 200 nautical miles towards the ocean, modeling it on the ECA in North America. The third scenario (DECA3), on the other hand, expanded the 12 nautical miles control zone along the whole coastline. To investigate the impact of shipping emissions on air quality, a shipping emission calculation model and an air quality simulation model were used, and Pearl River Delta (PRD), China was chosen to serve as a case study. The study demonstrated that in 2013 marine shipping emissions contributed on average 0.33 and 0.60µg·m-3, respectively to the land SO2 and PM2.5 concentrations in the PRD, and that the concentrations were high along the coastline. The DECA1 policy could effectively reduce SO2 and PM2.5 concentrations in the port regions, and the average reduction in the land area were 9.54% and 2.7%, respectively. Compared with DECA1, DECA2 would not measurably improve the air quality, while DECA3 would effectively decrease the pollution in the entire coast area. Thus, instead of expanding emission control area far to the ocean, it is more effective to control emissions along the coastline to secure the best air quality and lower the health impacts. By doing this, 19 million dollars of fuel cost could be saved per year. The saved cost could help the ship owners to endure, considering the current low profits of the seaborne trade, and thus to protect the overall growth of the economy.