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China, where coal is the dominant energy resource, accounted for 50.5% of the world’s coal consumption—or 1906.7 million tons of oil equivalent—during 2018. As a major source of volatile organic compounds (VOCs), coal utilization also led to high national emissions of these pollutants. In this study, we investigated the profiles; benzene, toluene, ethylbenzene, and xylene (BTEX) ratios; ozone formation potential (OFP); and secondary organic aerosol (SOA) formation potential of VOCs generated by coal-utilizing steel plants, power plants, coking plants, and residential stoves in northern China. Among the detected VOCs, the results identified 1-butene as the most abundant species for both the power plants (36.7%) and the residential stoves (41.7%) as well as a significant contributor at the steel plants (7.3%), and alkenes, alkanes, and aromatics composed the largest groups for the power plants (42.0%) and residential stoves (60.2%); steel plants (59.2%); and coking plants (66.1%), respectively. Additionally, the VOC profiles for power plants employing the same coal source or combustion technology exhibited strong similarities, although the BTEX ratios varied more between plants using different coal sources than those using different combustion technologies. Finally, alkenes were primarily responsible for the ozone formation (73.1%, 59.0%, and 87.6% for the power plants, steel plants, and residential stoves, respectively), whereas aromatics were primarily responsible for the SOA formation (more than 94.0% for all four coal-utilizing sources).

Rare earth elements (REE) are necessary for advanced technological and energy applications. To support the emerging need, it is necessary to identify new domestic sources of REE and technologies to separate and recover saleable REE product in a safe and economical manner. Underclay rock associated with Central Appalachian coal seams and prevalent in coal utilization waste products is an alternative source of REE to hard rock ores that are mainly composed of highly refractory REE-bearing minerals. This study utilizes a suite of analytical techniques and benchtop leaching tests to characterize the properties and leachability of the coal seam underclays sampled. Laboratory bench-top and flow-through reactor leaching experiments were conducted on underclay rock powders to produce a pregnant leach solution (PLS) that has relatively low concentrations of gangue elements Al, Si, Fe, and Th and is amenable to further processing steps to recover and produce purified REE product. The leaching method described here uses a chelating agent, the citrate anion, to solubilize elements that are adsorbed, or weakly bonded to the surface of clay minerals or other mineral solid phases in the rock. The citrate PLS produced from leaching specific underclay powders contains relatively higher concentrations of REE and lower concentrations of gangue elements compared to PLS produced from sequential digestion using ammonium sulfate and mineral acids. Citrate solution leaching of underclay produces a PLS with lower concentrations of gangue elements and higher concentrations of REE than achieved with hydrochloric acid or sulfuric acid. The results provide a preliminary assessment of the types of REE-bearing minerals and potential leachability of coal seam underclays from the Central Appalachian basin.

To limit global warming to a rise of 2 °C compared to pre-industrial levels, we cannot use all of our fossil fuel reserves; here an integrated assessment model shows that this temperature limit implies that we must leave unused a third of our oil reserves, half of our gas reserves and over 80 per cent of our coal reserves during the next 40 years, and indicates where these are geographically located. Regional choices between fossil fuels and climate warming If global warming is to be limited in this century to the much-publicized 2 °C rise compared to pre-industrial levels, fossil fuel use and the associated release of greenhouse gases will need to be severely limited. This raises questions regarding the specific quantities and locations of oil, gas and coal that can be safely exploited. Christophe McGlade and Paul Ekins use an integrated assessment model to explore the implications of the 2 °C warming limit for different regions' fossil fuel production. They find that, globally, a third of oil reserves, half of gas reserves and over 80% of current coal reserves should remain unused during the next 40 years in order to meet the 2 °C target and that the development of resources in the Arctic and any increase in unconventional oil production are incompatible with efforts to limit climate change. Policy makers have generally agreed that the average global temperature rise caused by greenhouse gas emissions should not exceed 2 °C above the average global temperature of pre-industrial times 1 . It has been estimated that to have at least a 50 per cent chance of keeping warming below 2 °C throughout the twenty-first century, the cumulative carbon emissions between 2011 and 2050 need to be limited to around 1,100 gigatonnes of carbon dioxide (Gt CO 2 ) 2 , 3 . However, the greenhouse gas emissions contained in present estimates of global fossil fuel reserves are around three times higher than this 2 , 4 , and so the unabated use of all current fossil fuel reserves is incompatible with a warming limit of 2 °C. Here we use a single integrated assessment model that contains estimates of the quantities, locations and nature of the world’s oil, gas and coal reserves and resources, and which is shown to be consistent with a wide variety of modelling approaches with different assumptions 5 , to explore the implications of this emissions limit for fossil fuel production in different regions. Our results suggest that, globally, a third of oil reserves, half of gas reserves and over 80 per cent of current coal reserves should remain unused from 2010 to 2050 in order to meet the target of 2 °C. We show that development of resources in the Arctic and any increase in unconventional oil production are incommensurate with efforts to limit average global warming to 2 °C. Our results show that policy makers’ instincts to exploit rapidly and completely their territorial fossil fuels are, in aggregate, inconsistent with their commitments to this temperature limit. Implementation of this policy commitment would also render unnecessary continued substantial expenditure on fossil fuel exploration, because any new discoveries could not lead to increased aggregate production.

early three-quarters of the growth in global carbon emissions from the burning of fossil fuels and cement production between 2010 and 2012 occurred in China1, 2. Yet estimates of Chinese emissions remain subject to large uncertainty; inventories of China’s total fossil fuel carbon emissions in 2008 differ by 0.3 gigatonnes of carbon, or 15 per cent1, 3, 4, 5. The primary sources of this uncertainty are conflicting estimates of energy consumption and emission factors, the latter being uncertain because of very few actual measurements representative of the mix of Chinese fuels. Here we re-evaluate China’s carbon emissions using updated and harmonized energy consumption and clinker production data and two new and comprehensive sets of measured emission factors for Chinese coal. We find that total energy consumption in China was 10 per cent higher in 2000–2012 than the value reported by China’s national statistics6, that emission factors for Chinese coal are on average 40 per cent lower than the default values recommended by the Intergovernmental Panel on Climate Change7, and that emissions from China’s cement production are 45 per cent less than recent estimates1, 4. Altogether, our revised estimate of China’s CO2 emissions from fossil fuel combustion and cement production is 2.49 gigatonnes of carbon (2 standard deviations = ±7.3 per cent) in 2013, which is 14 per cent lower than the emissions reported by other prominent inventories1, 4, 8. Over the full period 2000 to 2013, our revised estimates are 2.9 gigatonnes of carbon less than previous estimates of China’s cumulative carbon emissions1, 4. Our findings suggest that overestimation of China’s emissions in 2000–2013 may be larger than China’s estimated total forest sink in 1990–2007 (2.66 gigatonnes of carbon)9 or China’s land carbon sink in 2000–2009 (2.6 gigatonnes of carbon)10.

Coal gasification is recognized as the core technology of clean coal utilization that exhibits significant advantages in hydrogen-rich syngas production and CO2 emission reduction. This review briefly discusses the recent research progress on various coal gasification techniques, including conventional coal gasification (fixed bed, fluidized bed, and entrained bed gasification) and relatively new coal gasification (supercritical water gasification, plasma gasification, chemical-looping gasification, and decoupling gasification) in terms of their gasifiers, process parameters (such as coal type, temperature, pressure, gasification agents, catalysts, etc.), advantages, and challenges. The capacity and potential of hydrogen production through different coal gasification technologies are also systematically analyzed. In this regard, the decoupling gasification technology based on pyrolysis, coal char–CO2 gasification, and CO shift reaction shows remarkable features in improving comprehensive utilization of coal, low-energy capture and conversion of CO2, as well as efficient hydrogen production. As the key unit of decoupling gasification, this work also reviews recent research advances (2019–2023) in coal char–CO2 gasification, the influence of different factors such as coal type, gasification agent composition, temperature, pressure, particle size, and catalyst on the char–CO2 gasification performance are studied, and its reaction kinetics are also outlined. This review serves as guidance for further excavating the potential of gasification technology in promoting clean fuel production and mitigating greenhouse gas emissions.

A plant for liquefying organic matter has been create to solve the problems of using low-grade coals and waste coal utilization. The results of the performed studies are presented and the prospects for the solution of existing problem are shown, initial data are obtained for creating a pilot sample of the technological complex.

The quest for scientifically advanced and sustainable solutions is driven by growing environmental and economic issues associated with coal mining, processing, and utilization. Consequently, within the coal industry, there is a growing recognition of the potential of microbial applications in fostering innovative technologies. Microbial-based coal solubilization, coal beneficiation, and coal dust suppression are green alternatives to traditional thermochemical and leaching technologies and better meet the need for ecologically sound and economically viable choices. Surfactant-mediated approaches have emerged as powerful tools for modeling, simulation, and optimization of coal-microbial systems and continue to gain prominence in clean coal fuel production, particularly in microbiological co-processing, conversion, and beneficiation. Surfactants (surface-active agents) are amphiphilic compounds that can reduce surface tension and enhance the solubility of hydrophobic molecules. A wide range of surfactant properties can be achieved by either directly influencing microbial growth factors, stimulants, and substrates or indirectly serving as frothers, collectors, and modifiers in the processing and utilization of coal. This review highlights the significant biotechnological potential of surfactants by providing a thorough overview of their involvement in coal biodegradation, bioprocessing, and biobeneficiation, acknowledging their importance as crucial steps in coal consumption.

Coal is composed of numerous dense cyclic aromatic hydrocarbons, and understanding the molecular-level C-C bond reaction history is crucial for realizing cleaner and more efficient coal utilization. In this study, we employed 1,2-diphenylethane as a representative model compound to predict the thermal history through analysis of its pyrolysis products. Using 9,10-dihydroanthracene as a radical scavenger, we tracked the reaction pathways of carbon-based radicals, evidenced by the changes in the products. Furthermore, (DFT) calculations were employed to model the pyrolysis process, reinforcing the proposed radical reaction mechanism. We examined the effects of critical factors on radical behavior at the molecular level. To validate the general applicability of the free radical modulation mechanism, pyrolysis experiments were also performed on the aromatic fractions of raw coal, extending the findings from the model compound experiments. This study provides a detailed understanding of the relationship between C-C bond structures and reactivity during coal pyrolysis at the molecular scale, offering valuable theoretical insights that could aid in optimizing the control of radical processes in the pyrolysis of carbon-rich coal components.

Background The Xilingol grassland ecosystem has abundant superficial coal reserves. Opencast coal mining and burning of coal for electricity have caused a series of environmental challenges. Biogenic generation of methane from coal possesses the potential to improve economic and environmental outcomes of clean coal utilization. However, whether the microbes inhabiting the grassland soil have the functional potential to convert coal into biomethane is still unclear. Results Microbial communities in an opencast coal mine and in grassland soil covering and surrounding this mine and their biomethane production potential were investigated by Hiseq sequencing and anaerobic cultivation. The microbial communities in covering soil showed high similarity to those in the surrounding soil, according to the pairwise weighted UniFrac distances matrix. The majority of bacterial communities in coal and soil samples belonged to the phyla Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria. The dominant bacterial genera in grassland soil included Gaiella, Solirubrobacter, Sphingomonas and Streptomyces; whereas, the most abundant genus in coal was Pseudarthrobacter. In soil, hydrogenotrophic Methanobacterium was the dominant methanogen, and this methanogen, along with acetoclastic Methanosarcina and methylotrophic Methanomassiliicoccus, was detected in coal. Network-like Venn diagram showed that an average of 28.7% of microbial communities in the samples belonged to shared genera, indicating that there is considerable microbial overlap between coal and soil samples. Potential degraders and methanogens in the soil efficiently stimulated methane formation from coal samples by the culturing-based approach. The maximum biogenic methane yields from coal degradation by the microbial community cultured from grassland soil reached 22.4 μmol after 28 day. Conclusion The potential microbial coal degraders and methanogenic archaea in grassland soil were highly diverse. Significant amounts of biomethane were generated from coal by the addition of grassland soil microbial communities. The unique species present in grassland soil may contribute to efficient methanogenic coal bioconversion. This discovery not only contributes to a better understanding of global microbial biodiversity in coal mine environments, but also makes a contribution to our knowledge of the synthetic microbiology with regard to effective methanogenic microbial consortia for coal degradation.

Coal consumption leads to over 15 billion tons of global CO 2 emissions annually, which will continue at a considerable intensity in the foreseeable future. To remove the huge amount of CO 2 , a practically feasible way of direct carbon mitigation, instead of capturing that from dilute tail gases, should be developed; as intended, we developed two innovative supporting technologies, of which the status, strengths, applications, and perspective are discussed in this paper. One is supercritical water gasification-based coal/biomass utilization technology, which orderly converts chemical energy of coal and low-grade heat into hydrogen energy, and can achieve poly-generation of steam, heat, hydrogen, power, pure CO 2 , and minerals. The other one is the renewables-powered CO 2 reduction techniques, which uses CO 2 as the resource for carbon-based fuel production. When combining the above two technical loops, one can achieve a full resource utilization and zero CO 2 emission, making it a practically feasible way for China and global countries to achieve carbon neutrality while creating substantial domestic benefits of economic growth, competitiveness, well-beings, and new industries.