Coal Unit Research Articles

Assessment of Flexible Coal Power and Battery Energy Storage System in Supporting Renewable Energy

The use of renewable energy sources (RES) is expected to increase, potentially leading to volatility in the power system. Therefore, flexible power is essential to address this challenge. In China, two viable options for providing flexible power are battery energy storage systems (BESS) and flexibility modification of coal power units. This study introduces a framework to evaluate the costs of power system flexibility under varying RES shares on an hourly basis, comparing flexible coal power and BESS across several scenarios. In the short term, flexible coal power proves to be more advantageous than BESS, but BESS shows greater promise in the long run. The study suggests that while coal power will continue to play a critical role in the near future, it should gradually be phased out by reducing its utilization hours. Meanwhile, BESS should receive greater focus for long-term energy strategy. This study underscores the importance of maintaining power system stability throughout the low-carbon transition and highlights the need to balance short-term and long-term strategies for flexible power.

Systematic Exploration of the Interactions between Pyrite and Coal from the View of Density Functional Theory

Coal is often adhered to by pyrite during slime flotation, causing an increase in the sulfur content of clean coal. In order to study the mechanism of pyrite adhesion to coal surfaces, different coal structural units were built and optimized, and the most stable adsorption model of them on pyrite surfaces was determined. The mechanism of pyrite particles adhering to the surface of coal slurries was explored with the method of DFT. The results showed that the interaction mechanism between pyrite surface and Ph-OH and Ph-O-CH3 was the result of a weak interaction between the H atom of Ph-OH and Ph-O-CH3 and the S atom of the pyrite surface. The interaction mechanism between the pyrite surface and Ph-COOH and Ph-CO-CH3 was both as a result of H-S interactions and weak Fe-O interactions. On the whole, there were weak interactions between pyrite particles and the coal slurry, and the pyrite particles can spontaneously adsorb on the surface of the coal slurry.

Disaggregated Impact of Non-Renewable Energy Consumption on the Environmental Sustainability of the United States: A Novel Dynamic ARDL Approach

While there is a vast body of literature on environmental sustainability, the disaggregated impact of major non-renewable energy (NRE) consumption on the environmental sustainability of the United States (U.S.) is understudied, particularly in terms of using a load capacity factor (LCF) perspective. In this study, the above research gap is addressed using a dynamic autoregressive distributed lag (DYNARDL) model to analyze the heterogeneous impact of NRE consumption on the environmental sustainability of the U.S. from 1961 to 2022. Given the U.S.’s heavy reliance on energy consumption from NRE sources, this analysis provides an in-depth examination of the long-term effects of this energy consumption on the environment. Based on the analysis of the DYNARDL model, it is found that an increase of one unit of coal, natural gas, and petroleum energy consumption reduces environmental sustainability by 0.007, 0.006, and 0.008 units in the short-run and 0.006, 0.004, and 0.005 units in the long-run, respectively. However, one unit of nuclear energy consumption increases environmental sustainability by 0.007 units in the long-run. The kernel-based regularized system (KRLS) result reveals that coal and petroleum energy consumption have a significantly negative causal link with environmental sustainability, while nuclear energy consumption demonstrates a significant positive causal relationship. The research suggests the expansion of the use of nuclear energy by gradually reducing the utilization of coal and petroleum-based forms of energy, then natural gas, to improve environmental sustainability in the U.S., while considering the social and economic implications of efforts aimed at shifting away from the use of fossil fuels.

Repurposing coal plants into thermal energy storage—a techno-economic assessment in the Indian context

Abstract Substantial coal phase out initiatives have been growing as the world mobilizes to meet the Paris climate goals. However, the stranded asset risk associated with this critical transition could fall disproportionately on Asian economies with younger coal fleets, like India. Here, we undertake plant-level techno-economic analysis to explore the value of installing commercially available, molten-salt thermal energy storage (TES) systems for repurposing existing coal power plants in the Indian context. We combine process simulation and an economic optimization model to evaluate design and operations of TES systems for a variety of technology assumptions, coal plant archetypes, and electricity price scenarios. Key drivers of economic viability identified include longer remaining plant lifetime, increasing peak TES temperature, lower TES energy capacity cost, co-production of waste heat for end-uses, and increasing temporal variability of electricity prices. The plant-level analysis was then extended to screen for the potential of TES retrofits within the coal power fleet in Uttar Pradesh, the most populous Indian state with a significant share of India’s coal capacity. Analysis for a single electricity price scenario indicates that over 82% of the coal units in the state can be retrofitted and recover the installed costs of TES retrofits, provided that fixed operating and maintenance costs are excluded. These results reinforce the opportunity for decision-makers to consider TES retrofits of coal plants into cost-effective grid decarbonization strategies.

Optimization of coal power phaseout pathways ensuring energy security: Evidence from Shandong, China's largest coal power province

China has committed to peak carbon emissions before 2030 and achieve carbon neutrality before 2060. As the province with the country's largest coal power installed capacity, with soaring electricity and heating demands, Shandong has unique pathways to gradually phase out coal power. However, thus far, no studies have investigated coal power phaseout pathways at the provincial or national level with thorough consideration of energy security, encompassing both power and heating supply security. Here, we established five-dimensional criteria based on unit efficiency and environmental and technical attributes to evaluate unit-level coal power retirement priority and used an integrated resource strategic planning model to explore coal power phaseout pathways in Shandong. Overall, as many as 144 coal power units, which account for 6% of the total installed capacity, should have the highest retirement priority. Shandong could retire 100,000 MW of coal power by 2050 without compromising energy security through the ambitious development of low-carbon heating technologies. The evaluation criteria are applicable to various regions globally to assess coal power retirement priority. Shandong's case demonstrates the importance of low-carbon heating technology deployment in accelerating coal power phaseout to address climate change and facilitate energy transition.

Indentification of coal-origin structural units by multi-step pyrolysis through Py-GC/MS and by DFT calculation

Most of the existing structural models of coal macromolecules are based on indirect characterization, which cannot reflect the real product structure of coal pyrolysis. This study focuses on the construction of the real structural units of de-ashed Shendong coal (RD) and its vitrinite (VD) and inertinite (ID). Two pyrolysis modes of fast pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS), Thermogravimetry (TG), Fourier transform infrared (FTIR) as well as rapid infrared heating (RIH) were used to obtain the pyrolysis properties and product composition distributions of each coal. A strategy for structural unit construction of coal, termed “Molecular Reorganization”, is introduced to ensure that the original structure of the coal can be reproduced. Macromolecules produced by multi-step pyrolysis in the low-temperature region were used to assemble the real structural units of coal. The pyrolysis pathways of the oxygenated compounds in the constructed molecular unit models of RD-C70H50O9N, ID-C101H62O13N2, and VD-C71H43O9N were analyzed by density functional theory (DFT). The results showed that the reaction energy for the pyrolysis of ID fragments to phenol was higher, with fragments 1 and 2 being −4212.98 kJ/mol and −2190.83 kJ/mol, respectively.

Порівняльна оцінка собівартостей відпуску електроенергії з різних джерел в базовому та регулювальному режимах

The paper analyses the role and the technical and economic indicators of different electricity generation sources in the transition to "carbon-free" energy. A simplified method is proposed for estimating the minimally justified price of selling electricity from thermal power plants (TPPs), renewable energy sources (RES) and new maneuverable natural gas capacities is proposed. It is shown that the price of electricity from RES and new maneuverable capacity has a decisive influence on the amount and fixed period of return on investment in construction, as well as on the capacity utilization factor (CUF), which depends on the mode of operation of the power plants. Comparative estimates of the CUF of different electricity generation sources are presented. It has been shown that the cost of electricity from RES, new peak and maneuverable capacity is significantly higher than the cost of electricity from thermal power plants during the payback period. It is proved that at present the reserve for the reduction of the power shortage and the load regulation is available only in the thermal generation, and the conditions for the possibility of its effective use are the maintenance of the proper technical condition of the pulverized coal boiler units and the sufficient fuel base. To ensure acceptable electricity prices, RES and new control capacity should be phased in, using existing TPPs and CHPs to balance both the weighted average price and the regulation of power system load modes. Keywords: thermal power plants, coal, natural gas, gas turbine, steam-gas, gas-piston power plants, renewable energy sources, cost of electricity supply.

Analysis and Optimization of Black Water Angle Valve in Coal Gasification Unit

Analysis and Optimization of Black Water Angle Valve in Coal Gasification Unit

Towards Hydrogen Sector Investments for Achieving Sustainable Electricity Generation.

Hydrogen constitutes an integral component within an expansive array of energy technologies poised to facilitate the nation's transition towards achieving a net-zero state. In additional, this endeavor involves harnessing regional resources judiciously, thereby fostering equitable and sustainable growth. The strategic development and utilization of hydrogen technologies necessitate a nuanced approach, encompassing an assessment of diverse technologies spanning various sectors especially power sector. Such a meticulous strategy aims to forge the most efficacious, cost-effective, and sustainable pathways, underpinned by the discerning adoption of these technologies in the market. The article delves into the intricate relationship between hydrogen and fuel cell technologies, shedding light on their combined impact on the evolving landscape of electricity generation. A particular focus is placed on the integration of variable renewable energy sources, elucidating how hydrogen serves as a key enabler in optimizing the utilization of these fluctuating energy resources. In addition, the article encompasses various methods of hydrogen production, exploring their technological advancements and implications for achieving sustainable electricity generation. Emphasizing the significance of technology development in the hydrogen sector, the paper delves into the potential of hydrogen production methods and their implications for advancing sustainable electricity generation. In essence, the article navigates the trajectory of the hydrogen sector's evolution within the broader context of electricity generation, offering valuable insights into the ongoing developments, challenges, and opportunities. By addressing the critical nexus between hydrogen technologies and the dynamic electricity landscape, the paper aims to contribute to the discourse on the future trajectory of investments in the hydrogen sector for enhanced electricity generation. To Conclude, the United Kingdom has committed GBP 20 billion over a span of 20 years to the development of Carbon Capture, Utilization, and Storage (CCUS) facilities. Additionally, the nation has identified and shortlisted electrolysis projects totalling 408 megawatts (MW) capacity. In Korea, Hanwha Impact has achieved a significant milestone by attaining a 60% hydrogen co-firing share in an 80 MW gas turbine, representing the largest co-firing share recorded thus far in mid-to-large gas turbines. Meanwhile, Anhui Province Energy Group in China has successfully conducted trials involving the co-firing of ammonia at a 300 MW unit. The Group has plans to further extend these trials, aiming to achieve a 50% co-firing level at a 1 GW coal unit. In the United States, notable progress has been made, with a 38% hydrogen co-firing share attained in 2023 at an operational 753 MW combined-cycle power plant.

Optimal coal power phase-out pathway considering high renewable energy proportion: A provincial example

Since the announcement of the “carbon neutrality” goal, China has actively promoted the low-carbon transition across various industries. Controversy surrounds the fate of existing coal power units as, despite their carbon emissions, they remain integral to meeting the escalating power demand. Simultaneously, the integration of renewable energy sources (RES) underscores the need for coal power to provide flexible services, ensuring the safety and stability of the power grid. This study takes a province as example, establishing a comprehensive simulation model that considers a high share of RES to evaluate the optimal phase-out pathway for coal power in China. The analysis incorporates factors such as Carbon Capture and Storage (CCS), Battery Energy Storage System (BESS), and power demand growth. Results suggest that an immediate reduction in coal power capacity is not viable due to concerns about power supply safety. Recommendations emphasize the importance of maintaining a steady coal power capacity in the short term while concurrently developing RES, BESS, and CCS technologies. This approach facilitates a judicious withdrawal of coal power, contributing to cost reduction and ensuring a balanced transition. Furthermore, effective demand-side management emerges as a crucial.

Energy systems capacity planning under high renewable penetration considering concentrating solar power

With the rapid development of renewable generation and the promotion of “Clean Heating”, the uncertainty of renewables as well as rising energy demand has posed significant problems to the energy system’s economical and flexible operation. As a renewable energy generation technology, concentrating solar power (CSP) with thermal energy storage (TES) offers a promising approach by providing operational flexibility and thermal energy supply to the energy system. We propose a long-term high-resolution planning model considering the operational characteristics of CSP and improved flexibility constraints of energy systems under high renewable penetration to meet the electricity and heat demand simultaneously in this paper. By applying the proposed model to a typical “Clean Heating” area in China, it demonstrates that the optimal deployment by integrating CSP can reduce the peak-valley depth of coal units, minimize the renewable curtailment and carbon emissions by 37.64 % and 19.05 % respectively with more than 5.98 % cost reduction at 85 % renewable penetration compared with the base scenario, which provides an economic and stable zero-carbon pathway for multi-energy systems.

Episodic evolution of intracontinental orogenic deformation: Insight from the southern Bogda fold-and-thrust belt of the Tianshan Mountains, NW China

The Mesozoic-Cenozoic Tianshan orogenic belt, a key area for studying intracontinental orogenic deformation, experienced multiple uplift episodes due to the far-field effects from a series of collision events along the southern margin of Eurasia. Focusing on the fold-and-thwrust belt at the southern margin of the Bogda Mountain, a branch of the eastern Tianshan orogenic belt, we integrated 2D seismic data, borehole and outcrop data to construct a balanced and sequentially restored cross-section across the central part of this belt. The activities and mechanical evolution of the major faults were analyzed by using the discrete-element modeling (DEM) method, offering new insights into the tectonic transformation of the Turpan-Hami Basin influenced by episodic uplifts of the Bogda Mountain in an intracontinental setting. The studied fold-and-thrust belt can be divided into two deformation systems: (i) the piedmont deformation system, comprising a southward basement thrust system and a thin-skinned thrust system on Jurassic detachment, and (ii) the thrust front belt, exhibiting an en-echelon pattern in the basin center and featured by fault-propagation folds along the lower Jurassic coal unit. Stratigraphic and reported thermochronological analyses pinpoint four key contractional deformation periods: Late Jurassic, Late Cretaceous, Paleocene-Pliocene, and Pleistocene-present. The DEM numerical simulation results indicate a critical conical Coulomb wedge model governed by the episodic activities of the southern Bogda fold-and-thrust belts from the Mesozoic to the Cenozoic. Surface processes (syntectonic erosion/deposition) significantly impacted differential activities between the orogenic belt and the basin's thrust structures. We propose that periodic arid climates in the Tianshan Mountains reduced erosion rates, promoting the expansion of the southern Bogda fold-and-thrust belts toward the basin and the widening of the orogenic belt.

Analysis of the Operating Characteristics of a Photothermal Storage Coupled Power Station Based on the Life-Cycle-Extending Renovation of Retired Thermal Power Units

Analysis of the Operating Characteristics of a Photothermal Storage Coupled Power Station Based on the Life-Cycle-Extending Renovation of Retired Thermal Power Units

Optimal scheduling of deep peaking compensation for electric utilities considering multiple types of adjustable resources

Abstract This paper first analyzes the peak compensation process of electric power units in electric power enterprises, studies the carbon emission model of unit operation and the cost calculation method, then constructs an optimized dispatch model of deep peak compensation in electric power enterprises based on the factors of peaking subject and object and multiple types of adjustable resources, determines the critical peaking rate, and calculates the coefficient of the unit’s peaking capacity and the coefficient of the system’s peaking demand. Finally, based on the model, single-day and multi-day data from the regional power grid were analyzed, and the energy losses of the system units in summer and spring were compared before and after optimization. The results show that the average load factor of coal power units after the optimal dispatch of regional grid peak compensation is increased from 62%-68% before optimization to more than 91%, and the overall energy consumption of the system is reduced by 30.95% in the summer and 39.93% in the spring, which is of theoretical and practical significance for alleviating the scheduling pressure on the grid and the control problems of the power units.

Failure analysis of low-pressure steam superheater in a purification device

For a coal chemical enterprise purification unit in the low-pressure steam superheater in the use of frequent occurrence of heat exchanger tube bundle cracking, to find the cause of failure and ensure the safe and stable continuous operation of the device, the failure analysis work shall be carried out. In this paper, we have examined the cracked heat exchanger tube bundle in terms of macroscopic inspection, material chemical composition analysis, mechanical properties analysis scanning electron microscopy analysis, corrosion product analysis, metallurgical analysis, and many other tests, and also analyzed the internal and external media of the tube bundle, ultimately concluding the main reason for cracking of heat exchanger tube bundle for the alkali stress corrosion cracking. At the same time, to avoid similar problems, we hope that the failure analysis of the use and maintenance, inspection, and testing of the equipment provides a good solution to the failure of the equipment, and provides the best solution to the problem. It is hoped that this failure analysis will provide valuable experience for the use and maintenance of this type of equipment.

Carbon Footprint Analysis on Phosphoric Acid Production Using Wet Process at PT Petrokimia Gresik

Phosphoric acid is one of the main commodities in the fertilizer industry, which is very important in agricultural countries such as Indonesia. One of the biggest players in Indonesia’s fertilizer industry is PT Petrokimia Gresik, which owns a phosphoric acid plant that produces 200,000 MT/year phosphoric acid using the hemi-dihydrate process. Phosphoric acid production can be energy intensive and involve a lot of material transport, which usually corresponds with a high carbon footprint. To date, there is no literature regarding carbon footprint of Indonesia’s phosphoric acid. Thus, a carbon footprint analysis was done on phosphoric acid production at PT Petrokimia Gresik based on the inventory from their material and energy balance data. The electricity emission factor was calculated from their coal unit power plant, while the emission factor for raw materials was estimated from literature. The carbon footprint is 1378.25 kg CO2/ton P2O5. The largest carbon footprint contribution comes from sulphuric acid (43.81%), followed by material transport (36.78%). The sensitivity analysis shows that the carbon footprint was very sensitive to sulphuric acid and sea transport emission factor.

Microscopic seepage mechanism of CO2-alkaline-water in coalbed and its influence on coal wettability

The new developed technique, CO2-alkaline-water two-phase displacing gas and wetting coal (CADW), can obviously improve coal seam water injection effects. In this work, the microscopic seepage mechanism of CO2-alkaline-water in coalbed and its influence on coal wettability were investigated in detail. The results indicated that, the CADW measure could clearly increase coal wettability. After the CADW, the specific surface area of LS and ZX coals increased by 33.44%, 14.61% and the total pore volume increased by 121.60%, 19.48% respectively. Besides, the contact angle of two coals decreased by 25.30% and 6.62% severally. Further investigation showed that, the polar force increased evidently after using the CADW. As a result, the surface free energy of LS and ZX coals calculated by the Owens-Wendt method increased by 13.82% and 6.03%, that acquired by the Van Oss model increased by 10.26% and 6.32%, respectively. In addition, the CADW could obviously increase contents of hydrophilic groups in coal. The content of -OH in two coals increased by 20.09% and 32.10%, the CO density increased by 27.27% and 70.77% respectively. The results can provide valuable reference for preventing gas outburst risk and reducing mine dust concentration.

A Novel Surface Subsidence Prediction Model Based on Stochastic Medium Theory for Inclined Coal Seam Mining

Most coal resources are deposited in the form of inclined coal seams, and surface subsidence basin morphology induced by the mining of inclined coal seams is frequently skewed. The probability integral method with symmetrical distribution characteristics is widely used at present in surface subsidence prediction in coal mining in China. However, this method performs poorly when the inclined coal seam mining subsidence is predicted, and prediction accuracy decreases considerably with an increase in coal seam inclination. To solve this problem, this study first establishes three coordinate systems: a working surface rectangular coordinate system, a working face body-following coordinate system, and a surface rectangular coordinate system. Then, a random medium theory is applied to realize the superposition integral operation of the subsidence influence of unit mining in the working faces body-following coordinate system. Subsequently, the subsidence effect of a certain point on the surface is converted into the surface rectangular coordinate system. Finally, the inclined coal seam mining subsidence prediction model is constructed under the surface rectangular coordinate system. Results show that the surface subsidence caused by the mining of the inclined coal seam units conforms to the Weibull polar distribution law, and the effectiveness of the prediction model is verified through examples. The relative mean squared error of the prediction is less than 10%. The results of the study can provide theoretical and technical support for the subsidence prediction of similar mining areas.

Evolution law study of pore and fracture of coal gangue cemented filling body under axial compression using PFC2D

Filling body is an important structure to support the safety of coal mine goaf. The cemented gangue backfill (CGB) is a multiphase heterogeneous brittle material composed of coal gangue, hydration reactants, pores and microcracks. According to Micromechanics studies, the accumulation and development of meso-structural damage in heterogeneous brittle materials is the direct cause of macroscopic failure. In this paper, particle flow numerical software PFC2D is used to simulate the meso-structure evolution of CGB. Considering the particle size of filling material, the coal gangue particles are drawn according to the real shape by vector software, then import it into PFC2D by FISH language and constructed as Clump unit. The relationship between micro-characteristics such as particle force chain distribution, cracks and pores and mechanical properties of CGB is analyzed. The results show that the stress-strain and crushing mode of the numerical simulation model have a good correspondence with the laboratory test results. The internal force chain distribution and fracture-pore evolution law of the model particles are analyzed. It is found that most of the force chains are concentrated near the larger particle units, forming the 'skeleton force chain' phenomenon. The initial cracks are mainly produced around the coal gangue particle unit. With the increase of axial pressure, the cracks grow obliquely from 30° to 45°, and finally macroscopic cracks are generated. Due to the hydration product generated, the internal porosity is gradual decrease. Other than that, during the uniaxial compression process，the porosity of the same curing age decreases first and then increases, and the pores are sudden increase after the complete crushing stage.

SMART MINING: JOINT MODEL FOR PARAMETRIZATION OF COAL EXCAVATION PROCESS BASED ON ARTIFICIAL NEURAL NETWORKS

<p>In the present paper we propose a new artificial neural network model for the estimation of coal cutting resistance and excavator performance as a nonlinear relationship between the examined input (excavator movement angle in the left and right direction, slice height and thickness, coal unit weight, compressive and shear strength) and output factors (excavator effective capacity, maximum current/power/force/energy consumption, linear and areal cutting resistance). We analyze the dataset collected from three open-pit coal mines in Serbia: Field D, Tamnava Eastern Field and Tamnava Western Field (all part of the Kolubara coal basin). The model is developed using a multilayer feed-forward neural network, with a Levenberg-Marquardt learning algorithm. Results of the preformed analysis indicate satisfying statistical accuracyof the developed model (R>0.9). Additionally, we analyze the individual effects of input factors on the properties of coal cutting resistance and performance of the excavator, by invokling the multiple linear regression. As a result, we single out the statististically significant and physically possible interactions between the individual controlling factors</p>