Raw Coal Research Articles

Comparative research on the precursory characteristics of critical slowing down before the failure of raw coal and briquettes

Comparative research on the precursory characteristics of critical slowing down before the failure of raw coal and briquettes

The influence of inherent minerals on the constant-current electrolysis process of coal-water slurry

This study investigates the effect of inherent minerals on the constant current electrolysis of coal-water slurry (CWS), which is a potential method for energy-saving and value-added utilization of coal. The products and energy consumption of raw coal and demineralized coal (DM-coal) are compared, and the alkali-soluble and alkali-insoluble components are separated for electrolysis. The results show that minerals increase the yield of water-insoluble acid (WIA) from 30.02% to 60.02% and decrease the unit energy consumption from 2.7 kJ/g to 2.3 kJ/g. Additionally, the inherent minerals also affect the carbon skeleton structure of the products. Compared to DM-coal, the residual coal R4320 from raw coal exhibits lower carbonyl carbons (faC) and smaller sizes of aromatic clusters (Xb). The mechanism underlying the influence of inherent minerals is explored based on the dissolution patterns of minerals and the interaction between oxidizing medium and coal molecules. This study provides insights for energy consumption control and the coupling of anodic CWS oxidation with cathodic carbon dioxide reduction through current modulation.

Quantifying the impacts of coal mining activities on topsoil using Hg stable isotope: A case study of Guqiao mining area, Huainan City

The Hg released from coal mining activities can endanger soil ecosystems and pose a risk to human health. Understanding the accumulation characteristics of mercury (Hg) in coal mining soil is important for effectively controlling Hg emissions and developing measures for the prevention and control of Hg contamination. To identify the potential sources of Hg in soils, the Hg concentration and isotopic composition characteristics of raw coal and different topsoil types from the areas surrounding a coal mine were determined in this study. The results showed that Hg in coal mainly exists mainly in the form of inorganic Hg, and Hg has experienced Hg2+ photoreduction prior to incorporating into coal. In addition, the composition of Hg isotopes differed significantly among different topsoil types, and the δ202Hg value of the farmland soil exhibited large negative excursions compared to the coal mining soil. The ternary mixed model further revealed the presence of substantial differences in potential Hg sources among the two regions, with the coal mining soil being greatly disturbed by anthropogenic activity, and the relative contributions of Hg from raw coal, coal gangue, and background soil to coal mining soil being 33.42%, 34.4%, and 32.19%, respectively. However, Hg from raw coal, coal gangue and background soil contributed 17.04%, 21.46%, and 61.51% of the Hg in the farmland soil, indicating that the accumulation of Hg in farmland soil was derived primarily from the background soil. Our study demonstrated that secondary pollution in soil caused by immense accumulation of solid waste (gangue) by mining activities offers a significant challenge to ecological security. These findings provide new insights into controlling soil Hg in mining areas and further highlight the urgency of strict protective measures for contaminated sites.

Effect of organic carboxylates in coal on the production of active sites and coal self-ignition behavior

The heat release of coal oxidation lead to the thermal decomposition of carboxylic groups, which include carboxylic acid and carboxylate. However, few researchers have studied the effect of the decomposition of intrinsic carboxylate structure on coal self-ignition process. In this work, different coal samples were selected and treated with alkali solutions to form organic carboxylate structures, and the thermal decomposition of the raw and alkali-treated coals followed by the room temperature oxidation process were analyzed. The effect of the carboxylate structures on the thermal behavior, elemental distribution, and functional groups of coal was also studied by means of TGA, FTIR, XPS and EPR. The results showed that the carboxylic groups in coal were transformed into carboxylate structures by ion exchange. In addition, highly reactive free radical active sites were produced and accumulated along with the decomposition of carboxylates, thus accelerating the self-heating of coal. In the room-temperature oxidation experiment, the temperature of alkali-treated Wulan coal was spontaneously raised by 13.9℃, while that of raw coal was 4.3 ℃. The results showed that the thermal decomposition of organic carboxylate played an important role in promoting the spontaneous combustion of coal, and acid pretreatment could be a potential method to effectively inhibit the coal self-ignition process.

A study of the relationships between coal heterogeneous chemical structure and pyrolysis behaviours: Mechanism and predicting model

Coal is naturally heterogeneous on chemical structure, which significantly affects its pyrolysis behaviours. However, due to the limit of characterization tools, quantification of the chemical structural heterogeneity and its effects on pyrolysis are still challenging. In this study, a quantification method for chemical structural heterogeneity by Raman mapping technique was firstly proposed, and the heterogeneous chemical structure of coal was investigated. The results show that the distributions of the chemical structure are highly uneven, even though the average structural characteristics are highly similar. Besides, the effects of chemical structural heterogeneity on pyrolysis behaviours were studied. It is found that except for the average structural properties, the chemical structural heterogeneity affects the pyrolysis behaviours significantly. It is attributed to the different pyrolysis mechanisms and uneven distribution of these chemical structures with different reactivity. The effects of the average chemical structures and the chemical structural heterogeneity on the pyrolysis behaviours are independent. Furthermore, new predicting models for pyrolysis behaviours by considering both the average structure and the chemical structural heterogeneity were established and validated. The final models were proved to be adequate to effectively predict the pyrolysis behaviours of raw and blended coals.

Effect of extracts of petroleum ether, dichloromethane and methanol on thiophenic sulfur release during coal pyrolysis

The existing forms and thermal transformation of sulfur in high sulfur coal directly influence the efficiency of coal clean utilization by the staged pyrolysis conversion. Low molecular compounds distributed in coal are very different from the macromolecular structure of coal and play an important role during coal pyrolysis. In order to investigate the effects of low molecular compounds on the release of typical thiophenic sulfur species during coal pyrolysis by Py-GC/MS, petroleum ether, dichloromethane, and methanol were used for sequential ultrasonic extraction of Linfen coal (LFC). The compositions of extracts were detected by GC×GC/MS. Results show that three primary kinds of thiophenic sulfur species (2-methyl thiophene, benzothiophene, and dibenzothiophene) were released during coal pyrolysis and they are mainly derived from the cracking of macromolecular skeleton containing thiophenic sulfur in coal. The amounts of thiophenic sulfur released during raw coal and residues pyrolysis both increase with temperature. Besides, extracts with different compositions have different effects on the release of thiophenic sulfur during pyrolysis. In detail, the cyclization of aliphatic compounds could provide active hydrogen. On the one hand, the active hydrogen promotes the break of bridge bonds around thiophenic sulfur. On the other hand, active hydrogen may attack sulfur atoms of thiophenic sulfur, reducing the energy barriers of thiophenic sulfur decomposition. Aromatic compounds polymerize with sulfur-containing groups converting to benzothiophene and dibenzothiophene with larger molecular weight. In addition, thiophenic sulfur may be oxidized by esters to sulfones or sulfoxides, which further decompose, resulting in the inhibition effect on thiophenic sulfur formation during coal pyrolysis.

Alterations in coal mechanical properties and permeability influenced by liquid CO2 phase change fracturing

Liquid CO2 phase change fracturing (LCPCF) is a promising approach for stimulating coal reservoirs and enhancing gas drainage efficiency of low-permeability coal seams. In this work, low pressure CO2/N2 adsorption, CH4 permeability measurements and UCS tests are combined to quantitatively analyze the changes in coal mechanical properties and permeability before and after LCPCF treatment. The results show that the axial peak strain is increased and ductile failure takes place in treated specimens after 1.26 L of liquid CO2 was used to conduct physical blasting. The UCS and elastic modulus after LCPCF are reduced by 10.82–25.78% and 12.92–28.57%, respectively. Muti-scale pore structures within coal are altered to varying degrees. After LCPCF treatment, mesopore volume and macropore volume are increased by 11.33–41.57% and 33.82–67.5%, respectively, while micropores are slightly affected. Due to the adsorption swelling and Klinkenberg effect, CH4 permeability of all the specimens is reduced with the increase of injection pressure. Comparative analysis of gas permeability has been made between the raw coal and treated specimens. Coal permeability is enhanced by 14.48-29.43% and 10.54-24.82% after LCPCF treatment at the injection pressure of 0.5 MPa and 1.4 MPa, respectively. During the LCPCF process, shock waves and stress waves trigger tensile damage to coal mass, and a large number of new macropores/fractures are generated within coal. This provides more accessible paths for gas flow and coal permeability are greatly promoted. Crack propagation is accelerated by the released high-pressure CO2, and both coal porosity and pore connectivity are further enhanced to facilitate gas seepage in coal seams.

Incorporating scarcity into footprints reveals diverse supply chain hotspots for global fossil fuel management

In the current context of energy and geopolitical crises, the sustainable supply and use of energy play a critical role in responding to climate change and the global transformation towards a low-carbon economy. The supply-chain risks of fossil fuels (i.e., raw coal, crude oil, and natural gas) are closely linked to sustainable production and consumption, emphasized by Sustainable Development Goals (SDGs). However, the impacts of scarcity or endowment of fossil fuels on the global scale remain unknown, which hinders sustainable fossil fuel management from a global perspective. This study analyses the scarcity-weighted fossil fuel extractions (i.e., supply side) and footprints (i.e., demand side) of nations. It identifies the hidden supply-chain risks that cannot be revealed when focusing on supply or demand itself (e.g., France, Norway, and Ecuador from the supply side, and France, Germany, and Norway from the demand side). Moreover, the net trade (= import-export) flows of embodied fossil fuels of certain nations (e.g., France, Australia, and Russia) have even reversed. The novel findings of this study demonstrate the importance of incorporating scarcity footprint into the SDG framework to reveal the hidden supply-chain risks. They could inform more explicit and targeted implications for global sustainable fossil fuel management. Under the background of complex international energy trade relations, nations with high risks should accelerate their energy transitions and strengthen international cooperation from both supply and demand sides.

Effects of oxidation temperature on microstructure and spontaneous combustion characteristics of coal: A case study of Shendong long-flame coal

To identify effects of the pre-oxidation process on the spontaneous combustion characteristics of Shendong low-rank long-flame coal, the microstructure and oxidation reactivity of coal samples pre-oxidized at different temperature including 70 °C, 100 °C, 200 °C, 300 °C, and 400 °C were studied and compared with those of raw coal. The surface morphology, pore features, functional groups, and microcrystalline structure of coal were studied using SEM, N2 adsorption, XPS, and XRD analyses. Moreover, TG-DSC experiments were conducted to investigate the changes in the spontaneous combustion characteristics of coal. The results indicated that low-temperature pre-oxidation at 70 °C and 100 °C does not alter the physical and chemical structure significantly, so the pore parameters, functional group contents, and microcrystalline structure of these two samples were very similar to those of raw coal. When the pre-oxidation temperature reached and exceeded 200 °C, the specific surface area and total pore volume of coal samples exhibited a significant decrease due to extensive thermal decomposition and consumption of coal components via oxidation. Moreover, high-temperature pre-oxidation treatment above 200 °C sharply reduced the aromatic and aliphatic carbon C–C/C–H content, and this is ascribed to the substantial consumption of primordial organic matter, this made coal macromolecules more tightly packed with an increase in carbon crystal size and carbon matrix order. In addition, with increasing temperature from 200 °C to 400 °C, the C–C/C–H contents decreased and aromaticity of coal increased, which revealed the weak oxidative activity. The heat release △H1 from 30 °C to 300 °C of coal samples after pre-oxidation at 200–400 °C was significantly lower than that of raw coal, while the △H1 values of coal samples treated at 70 °C and 100 °C were close to that of raw coal. Notably, that oxidation treatment at 70 °C resulted in an increase in the amount of heat released, because of the largest specific surface area that increases the risk of spontaneous combustion. Thus, the pre-oxidation treatment increases the risk of spontaneous combustion of coal when the pre-oxidation temperature is lower than a critical temperature.

Study on thermal effects and gases derivation of spontaneous combustion of gas-containing coal

Heat release and gas derivation can reflect the degree of coal spontaneous combustion (CSC) as important indicators. Meanwhile, both physical and chemical properties of gas-containing coal and methane molecules are important factors for CSC. The C600 high-precision microcalorimeter was coupled with a gas chromatograph to conduct oxidation and pyrolysis experiments on gas-containing coal. The thermal effects and gas derivation rules in the process were analyzed. The influence of the physicochemical properties of gas-containing coal on the spontaneous combustion process was clarified. The quantitative relationship between particle size and heat release coal was discussed. The experimental results show that compared with raw coal, the unique characteristics of gas-containing coal are as follows: (1) The oxidation process is slowed down, while high temperature combustion is more adequate, and pyrolysis is more likely to occur and more intense; (2) The heat absorption and release intensity increased to different degrees, and the characteristic temperature shifted forward; (3) With the decrease of oxygen consumption and generation of CO2, CO release increases significantly; (4) As the particle size of gas-containing coal decreases, the oxidation is more likely to occur, while pyrolysis is slowed down. The research results provide an important theoretical basis for the prevention and control of spontaneous combustion of gas-containing coal.

Experimental and quantum chemical investigation on the inhibitory effects of Resveratrol on coal spontaneous combustion

The inhibitory effect of antioxidants on the prevention of coal spontaneous combustion (CSC) has been tremendously studied. In this paper, we investigated the inhibitory effect of Resveratrol (RES) on CSC. The oxidation properties of coal were revealed by a temperature-programmed test. Mass changes and heat flow effects of coal oxidation was investigated by TG-DSC. Fourier-transform infrared spectroscopy was conducted to confirm the variations in reactive groups in coal. Furthermore, combining the above results, the reaction mechanism of RES was analyzed by the Quantum chemical theory. The results show that different concentration of RES (5 wt%, 10 wt% and 15 wt%) exhibits an extraordinary ability to prevent CSC. After the 10 wt% RES treated, the apparent activation energy of treated coal obtained an 11.85 kJ/mol increase. The RES-treated coal achieved a maximum inhibition rate of 79 %, a lower mass loss rate than that of the raw coal, and a 20 % reduction in the maximum heat flow. In addition to carboxylic groups, the content of other active groups decreases after RES-treated. RES provides protonated hydrogen, which consumes oxygen-containing radicals and inhibits the formation of new hydrocarbon radicals. The proposed RES is water-soluble antioxidant which can be dispersed evenly on the coal surface and has been convinced as an effective antioxidant in preventing CSC.

Investigation of the effect of different distilled water, rainwater and seawater mass ratios on coal spontaneous combustion characteristics

When water comes into contact with coal, the risk of coal spontaneous combustion should be reassessed. In order to analyze the effect of distilled water, rainwater and seawater on the coal self-heating, thermogravimetric analysis (TGA) was applied to investigate the differences between the macroscopic oxidation properties of raw coal and water-immersed coal. The risk of coal spontaneous combustion increases after water immersion, but different types of water have different degrees of influence on the spontaneous combustion of coal. The microscopic pore structure and elemental changes on the surface of coal samples before and after water immersion were studied by Scanning Electron Microscope (SEM), low-pressure nitrogen gas adsorption (LP-N2GA) and Energy Dispersive Spectroscopy (EDS) experiments. Fourier infrared spectroscopy (FTIR) was used to investigate the change of active groups. The results show that the pore structure of coal samples immersed in water is much more developed than that of raw coal. In the low-temperature oxidation stage, moisture evaporation consumes much oxidation heat and inhibits the coal self-heating. After the stage, it promotes the coal spontaneous combustion. The content of the hydroxyl group increases, and the content of carbonyl and carboxyl decreases. The alkali metal elements can act as catalysts and active carriers of oxygen, enhancing the oxidation activity of coal. The results are helpful to understand the mechanism of different distilled water, rainwater and seawater mass ratios on coal spontaneous combustion and avoid potential self-heating after immersion.

CFD Simulation Based Ventilation and Dust Reduction Strategy for Large Scale Enclosed Spaces in Open Pit Coal Mines—A Case of Coal Shed

The coal shed is an enclosed space where raw coal is stored and handled. The intensive operation of the machinery inside the coal shed generates a large amount of dust, and the wind speed inside the enclosed space easily leads to a high concentration of dust, which endangers the physical and mental health of the workers. In this paper, we first studied the particle size distribution of dust samples in the coal shed and found that 12.2% of the dust in the air of the coal shed was 10–100 μm, 87.8% was less than 10 μm, and 72.9% was less than 2.5 μm. Fluent was used to simulate the law of dust dispersion in the coal shed under different working conditions, and finally, the simulation results were used to guide the design of the ventilation site and dust-reduction scenario. The experimental and simulation results show that under the same working conditions, the average dust reduction efficiency of the ventilation method in which the north side and south side pump air outside was 9.9%. The ventilation method in which the north side blows inside and the south side pumps outside was 23.7%. The average dust reduction efficiency of the ventilation method in which the north side blows inside and the south side pumps outside + placing the fan in the middle was 59.9%. The research results can provide some reference value for indoor air quality improvement.

Sulfur migration and distribution during pyrolysis of a typical Chinese pyrite-enriched coal

ABSTRACT Sulfur migration and distribution during pyrolysis of coal is quite complicated with the effect from different intertwined influencing factors, which requires extensive investigation. In this research, a typical Chinese pyrite-enriched coal was selected and pretreated through acid leaching combined with CrCl2 reduction. Thereby, minerals such as silicates and sulfates in the raw coal were effectively separated with the ash contents decreased from 37.74% to 0.57% while the inorganic sulfur was completely removed. Furthermore, programmed combined with isothermal pyrolysis of the selected coal and its two pretreated counterparts were conducted on the home-designed horizontal reactor to systematically ascertain the gaseous sulfur evolution. Possible sulfur formation pathways were revealed to explain the effect from the intertwined factors between the reaction temperature and the intrinsic factors as minerals distribution, different sulfur occurrences and their association with the organic matrix of coal. Finally, quantitative evaluation of the temperature effect on the sulfuric gases distribution and their yields was conducted with the total fraction of all the gaseous sulfur much decreasing from 5.6% to below 2.0% for the deashed and depyrited coal. Overall, through such a systematic investigation on the sulfur evolution from a typical pyrite-rich coal, comprehensive insights were obtained for future efficient sulfur control.

Study on the effect of inorganic and organic sodium on coal spontaneous combustion

In order to investigate the effect of sodium in coal spontaneous combustion, different types of inorganic and organic sodium were added to the raw coal to analyze the changes of spontaneous combustion characteristics of coal samples. The combustion characteristics parameters of each group of coal samples were calculated by simulating the spontaneous combustion reaction process of coal through programmed warming thermogravimetric experiments, and the results showed that the combustibility index of coal samples loaded with various types of sodium-containing reagents increased by 8.32 %–45.37 %, and the combustion characteristics index decreased by 13.82 %–39.15 %. It indicates that inorganic sodium salts and organic sodium salts promote the combustion of coal in the low temperature stage and inhibit it in the high temperature stage. Subsequently, the changes of characteristic functional groups in coal during combustion after loading sodium were analyzed by using in-situ infrared spectroscopy experiments, and it was concluded that sodium in organic salts would combine with peroxyl radicals and thus inhibit the oxidation process of oxygen-containing functional groups in coal; sodium in inorganic salts would replace hydrogen in carboxyl and hydroxyl groups and thus promote the oxidation reaction of coal. The results of the study can provide some theoretical basis for the development of new coal spontaneous combustion inhibitors with specific functions.

Experimental Study of New Antioxidant to Inhibit Spontaneous Combustion of Coal

ABSTRACT Free radicals and metal ions are key factors causing coal spontaneous combustion. In order to effectively suppress coal spontaneous combustion, experiments were conducted using luteolin as an inhibitor, luteolin is abbreviated as LUT. The influence of different concentrations of LUT on the spontaneous combustion heat characteristics of coal was tested using a C600 high-precision microcalorimeter, and the inhibition mechanism was inferred by FTIR. The experimental results show that LUT is an effective coal oxygen inhibitor, under the same action conditions, different concentrations of LUT can absorb heat to different degrees, delay the initial exothermic temperature of coal, prolong the heat absorption phase of coal. Compared with raw coal, 6 wt% LUT absorbs the most heat, the starting exothermic temperature is delayed by 46°C, and the activation energy is increased by 47.89 kJ/mol, the functional group -OH content decreased by 43.4%, -CH3 decreased by 32.1%, -CH2-decreased by 37.76%. Based on this, the mechanism of inhibition is inferred, LUT not only removes free radicals (ROO•) during the chain initiation stage and captures free radicals (•OH) in the reaction chain but also chelates metal ions to inhibit the catalytic effect of metal ions during the free radical reaction, which can play a dual role in preventing free radical generation and interrupting the free radical chain reaction. The results of the study can provide a novel, environmentally friendly and effective way to prevent the spontaneous combustion of coal.

Orthogonal Experimental Study on the Construction of a Similar Material Proportional Model for Simulated Coal Seam Sampling

The development of similar materials is crucial for conducting simulated coal seam sampling experiments. These materials must comprehensively consider the similarity of mechanical properties with raw coal. To ensure a high degree of similarity between the simulated coal seam similar material and raw coal, cement and coal powder were selected as the main influencing factors. This study employed sensitivity analysis and analysis of variance methods to investigate the impact of various factors on the compressive strength, elastic modulus, Poisson’s ratio, and density of comparable materials. The influence of moisture content on the compressive strength and elastic modulus of these materials was also analyzed, as well as the effect of cement and coal powder on moisture content. The results showed that cement was the main controlling factor for the mechanical properties of similar materials. Moreover, the variation of tensile strength and elastic modulus of similar materials in response to the moisture content can be divided into three distinct stages. Based on the influence law, the ratio formula of coal powder and cement for the strength and moisture content of similar materials was obtained, and a proportional model for simulated coal seam sampling similar materials was constructed. The approximate ranges of various parameters that can be achieved by this model are as follows: compressive strength of 1~11.4 MPa, elastic modulus of 0.27~3.62 GPa, Poisson’s ratio of 0.229~0.357, and density of 1.044~1.341 g·cm−3. The error in mechanical parameters for this model has been verified to be within 20%. Finally, similar materials were created for simulated coal seam sampling by employing an appropriate ratio. A self-developed drilling test platform was utilized to successfully conduct an experiment, further demonstrating the reliability of the proportional model.

A comparative evaluation of co-gasification of blends of low grade and washed coals with high-rank coal in a fixed bed reactor

ABSTRACT Coal is the most valuable gasification resource due to its abundance and low cost for commercial applications. But utilization of low-rank Indian coals for gasification is challenging due to difficulty in washing. For utilizing low-grade high ash raw coal, blending is one of the effective methods to control the gasification performances. So, the present study explores the gasification of such a low-rank raw coal blend and compares the results with washed coal blend. The blending effects on raw gas yield (kg/kg of coal) and heating value (Kcal/Nm3) were investigated for coal blends-WH (washed coal with high-rank coal) and RH (raw coal with high-rank coal). In WH, raw gas yield is 1.210 to 1.225 (kg/kg of coal), whereas, in RH is 1.189 to 1.213 (kg/kg of coal), though the fixed carbon content of WH (40.75–41.74%) is lower than RH (44.73–45.25%). In washed coal, raw gas yield is minimum (0.75 kg/kg of coal). The heating value is lower in WH (2730–2871 Kcal/Nm3) than in RH (2884–2978 Kcal/Nm3). Statistical correlation is developed between gaseous components of raw gas and heating value; H2/CO ratio is the most significant parameter. RH gasification is economically viable than WH.

Experimental study on changes in components and pore characteristics of acidified coal treated by organic solvents

Chemical solvents could change coal components and effectively enhance conductivity of coal reservoir, which is beneficial to efficient methane extraction. Relationship between coal chemical structure parameters and main functional groups variations affected by acidification and tetrahydrofuran (THF) is investigated through infrared spectroscopy tests and curve peak fitting. Meanwhile, variations in fractal dimensionality and pore structure characteristics are studied by adopting low-temperature nitrogen adsorption tests and Frenkel-Halsey-Hill (FHH) fractal model. Main results are: (1) After extracting raw coal and acidified coal using THF with varying concentrations, absorbance of aromatic hydrocarbon –CH surface and aromatic methyl bond become weaker. While the proportion of substituted aromatic hydrocarbons increases in acidified coal than in raw coal. Acidification treatment could reduce strength of C-O-C absorption peak. Proportion of CH2 and CH3 in raw coal decreases with increasing THF concentration, indicating that THF could react with aliphatic structure to reduce CH2 and CH3 content. Extraction with THF dissolves aromatic structure, lowering C = C content in coal to different degrees. (2) Acidification pretreatment could produce more micropores in coal samples. Micropore contents of acidified coal after THF extraction are all lower than coal sample S, while transition pores and mesopores contents are both higher than those in coal sample S. (3) Fractal dimension D1 of raw coal indicates a relatively linear relationship with specific surface area, while the D1 of acidified coal is less correlated with specific surface area. The factor D2 shows a linear relationship with average pore size. After treatment of THF, average pore size of raw coal increases with D2, while that of acidified coal varies in different degrees with uneven distribution of pore sizes.

Decomposition and decoupling analysis of multi-sector CO2 emissions based on LMDI and Tapio models: Case study of Henan Province, China.

The peak carbon dioxide emissions at the provincial level is the foundation for achieving the national target of carbon emission peak, thus it is important to analyze the characteristics of provincial CO2 emissions. However, there is a lack of comprehensive analysis and research on quantifying the contributions of the driving factors to decoupling at the provincial level. Therefore, taking Henan Province as the research object, this study establishes the decoupling effort model by combining the traditional LMDI model and Tapio model based on compiling the CO2 emission inventories from 2006 to 2019. The results showed that total CO2 emissions increased from 2006 to 2011, and decreased after 2011 in Henan Province. Raw coal was the primary fuel source of Henan's CO2 emissions, and the sector of "power and heat production" was the major industrial source, accounting for above 45% of the total emissions. Economic output and energy intensity were the major factors promoting and restraining the increase in Henan's CO2 emissions, respectively. In terms of the decoupling state, Henan achieved the transformation from weak decoupling to strong decoupling from 2006 to 2019. Industry presented a strong decoupling condition, while weak decoupling was detected in the agriculture sector during the study period. The changing trend of energy intensity decoupling effort was consistent with that of total decoupling effort, indicating that energy intensity is a crucial factor in achieving decoupling. This study is helpful to grasp the CO2 emission characteristics of Henan Province and provide the theoretical basis for formulating emission mitigation measures of peak carbon dioxide emissions in Henan and other provinces.