Chinese Coal-fired Power Plants Research Articles

Applications and analyses of ammonia slip control based on precise ammonia injection technologies guided by big data

Abstract After the implementation of ultra-low emission policies, the pollutant emissions from the coal-fired power generation systems in China have been further reduced, which creates more critical requirements for the control accuracies of denitrification systems using selective catalytic reduction technology and controls of ammonia slip. This article presents big data-based technologies for controlling ammonia slip, through precise ammonia injections, which were applied and demonstrated for a flue gas denitrification system of a Chinese coal-fired power plant. Through examinations and analyses of the basic operating conditions of the unit and parameters, such as NOx emission control efficiency, ammonia injection amount of the denitrification system, and non-uniformity of NOx concentrations in the denitrification zone were compared before and after the implementation of these technologies, the outcome proves that this artificial intelligence algorithm based on big data can effectively solve the automatic control problem of denitrification system under complex working conditions such as varied unit loads, day and night operation changed coal source. In addition to the effective controls of the ammonia slip of the system, the controls of NOx emission of the system become more stabilized, creating a successful example for wider applications of these precise ammonia injection control technologies in the future. Analyses show that NOx non-uniformities can be reduced by more than 50% under both stable and variable load conditions. NOx fluctuations at the unit outlet are tightly controlled within ±10 mg/Nm3 under variable load conditions and within ±5 mg/Nm3 under stable conditions. The average ammonia injection amounts under various load conditions have decreased by 15.7%.

Bayesian Vector Autoregression Analysis of Chinese Coal-Fired Thermal Power Plants

Considering the dataset of information related to Chinese coal-fired thermal power plants during the 2005–2017 period, we initially investigated the orthogonalized response of the carbon emission to energy consumption and power generation by using Bayesian vector autoregressions and feedback solutions for impulse control technology. The results showed that the effects of energy consumption and power generation on carbon emissions were significant. The Chinese government has launched a program aimed at curbing carbon emission peaks and neutralizing or decreasing carbon emissions. The causal relationship concludes that China still needs further investment in emission abatement, improvement related to the level of openness to the outside world, and the strengthening of the construction of green zones for industrial transfer to mitigate carbon emissions.

Assessment of Metal Impurity Partitioning and Speciation in Mineral Carbonation Processes Using FGD-Gypsum from Coal-Fired Power Plants under Distinct Operating Conditions.

The sequestration of carbon dioxide (CO2) stands as a profoundly pivotal environmental challenge, given its potential to directly contribute to the advancement of environmental, societal, and economic objectives across a multitude of nations. In the present study, we have conducted an evaluation of the metal impurity partitioning and speciation in mineral carbonation processes conducted in laboratory using flue gas desulfurization (FGD) gypsums originating from both Spanish and two Chinese coal-fired power plants, each subject to distinct fuel sources and FGD operational conditions. Of the three resultant carbonation products, two exhibited CaCO3 content in the range of 81-83%, while the third registered 76.9% CaCO3 content-a variance attributed to the occurrence of metallic impurities within the initial FGD-gypsum. The partitioning and speciation of metal impurities at all stages of CO2 conversion have enabled us to proffer four potential reaction mechanisms governing carbonation efficiency: (i) conversion of metal sulfates to metal carbonate complexes, (ii) transformation of transferable elements into metal oxides and oxyhydroxide complexes, (iii) transformation of metal sulfates into diverse metal complexes, and (iv) diverse pathways of elemental transformation. Metal impurities present in FGD-gypsum lead to the formation of complexes between As and metals, thereby affecting their activity. Higher Ca/Mn, Ca/Fe, and Ca/Al ratios in one FGD-gypsum slurry enhance Ca3(AsO4)2·8H2O activity, while in another, excess Ca facilitates Mn3(AsO4)2·8H2O formation during carbonation, with coprecipitation retaining As in carbonation products. The occurrence of metallic contaminants in FGD-gypsums may exert a substantial influence on the effectiveness of CO2 conversion, thereby impacting the feasibility of using resultant carbonation products, with potential implications for environmental leaching and diminished reusability prospects.

Emissions of volatile organic compounds from Chinese coal-fired power plants: Characteristics, source profile, inventories, and impacts

Volatile organic compounds (VOCs) are key precursors for secondary organic aerosols (SOA) and ozone, imposing severe impacts on human health and environment. Considering the massive coal consumption, coal fired power plants (CFPPs) in China are non-negligible VOCs contributors, whose emission characteristics remain inadequately understood. Here, we investigated emission characteristics of 117 VOCs by field tests in four typical CFPPs, and a latest localized CFPPs source profile was compiled by integrating literature reviews. Then speciated-VOCs emission inventories for 2018–2022 were established based on dynamic emission factors and unit-level activity data. The results suggested that oxygenated VOCs (OVOCs) constituted the dominant group (76.5 %), with propionaldehyde (32.0 %) and formaldehyde (24.5 %) being the predominant species. OVOCs (93.2 %) and aromatics (77.4 %) were identified as the primary contributors to ozone and SOA, respectively. Driven by both the rise in coal consumption and technological advancements, nationwide VOCs emissions decreased from 83,393 t in 2018 to 53,251 t in 2022. Regional disparities and varying rates of decline in provincial emissions were evident, with VOCs emissions predominantly concentrated in northern and eastern provinces. Neimenggu, Shandong, Shanxi, Jiangsu, and Guangdong were identified as the top five provinces with the highest emissions. We believe this study would be conducive to a more comprehensive understanding and effective control of VOCs emissions from CFPPs in China.

The Current Status and Future Prospects of Carbon Capture, Carbon Transportation, And Carbon Utilization Technologies in Chinese Coal-Fired Power Plants Within the Context of Dual Carbon Goals

Carbon dioxide capture, utilization, and storage (CCUS) constitute vital measures for achieving net emissions reduction in China. Against the backdrop of the “dual carbon” initiative in China, this paper meticulously examines and analyzes the key technological principles, merits and demerits, and bottlenecks associated with CCUS carbon capture in the country’s thermal power plants at the current stage. It combines the prevailing industrial application status and the future development trajectory of pertinent technologies with considerations of industrial economic benefits and business models. Building upon this analysis, the paper summarizes the application status of CCUS technology in China’s thermal power plant industry and presents future prospects. On the technological front, the three capture methods grapple with the challenge of high costs. Therefore, there is a need to intensify efforts in developing low-cost and efficient carbon capture materials, as well as researching and practically applying low-cost oxygen generation technology. Economically, CCUS technology currently faces high costs, low returns, and certain commercial barriers, placing China in a demonstrative business model stage. To overcome these challenges and realize the economic benefits of CCUS technology, government incentives and technological innovation are imperative. These measures aim to reduce the overall cost of CCUS technology, stimulate the scale development, and foster commercialization, ultimately contributing to the achievement of China’s carbon emission reduction targets.

Diversionary Post-Coal Politics in South Africa: A Chinese Solar-Powered Industrial Zone Controversy

In September 2021 at a United Nations climate summit in New York, Xi Jinping announced that there would be no further Chinese coal-fired power plants along the Belt and Road Initiative, which stretches as far as South Africa. Instead, the Chinese operator of South Africa’s single largest Special Economic Zone proposal – in rural Makhado – and his local allies suggested that solar power could supply energy for the $10 billion project, including high-emissions industrial projects. This raised the question of whether firms engaged in mining, smelting, processing and other carbon-intensive activities would pick ‘low-hanging fruits’ within the renewable energy sector (instead of that power going into the grid for broader consumption). Their incentive is to do so, in order to safeguard the so-called Minerals-Energy Complex from Western climate sanctions – threatened, on grounds of high CO2-inputs to export products including steel, aluminium and petrochemicals. In spite of a 2022 United Nations Development Programme endorsement of the project, social and environmental resistance has intensified, but the introduction of solar power for high-emissions metal manufacturing presents a special challenge. Two techniques associated with ecological modernisation – natural capital accounting and the Social Cost of Carbon – may prove relevant to civil society critics of ‘extractivism’, in shifting the narrative further across space, time and scale.

Analysis of emission evolution and synergistic reduction effect of air pollutants and CO2 from Chinese coal-fired power plants

The coal-fired power industry is the largest coal-consuming sector in China, and it serves as a significant source of air pollutants and carbon emissions. In this study, we investigated the evolution of air pollutants and CO2 emissions originating from coal-fired power plants (CFPPs) from 2013 to 2020 based on a unit-based bottom-up inventory, and then we quantitatively assessed their combined reduction effects from 2013 to 2060. Our findings indicated that air pollutant emissions experienced a rapid decrease from 2013 to 2020, with nearly 46.0%–64.2% of the reduction occurring within the years 2013–2017. However, CO2 emissions displayed a slight increase during the same period. The top five provinces with the most robust synergistic reduction effects for both air pollutants and CO2 were Jiangsu, Hebei, Henan, Shanxi, and Shandong. The primary measures to the reduction in CO2 emissions were energy structure adjustment and energy conservation and consumption reduction. By 2060, emissions of PM2.5, SO2, NOx, Hg, and CO2 had decreased by 57.9–92.1%, 26.0–80.6%, 18.1–69.4%, 26.6–86.3%, and 35.8–76.1% compared to the levels in 2020, respectively. As the emission reduction process advanced, the reduction effect on CO2 became more pronounced within the synergistic process. We believe that our highly detailed emission inventory comprehensively captures the historical evolution of PM2.5, SO2, NOx, Hg, and CO2 emissions from CFPPs. Furthermore, the scenario analysis results we have obtained will be instrumental in supporting policy development aimed at achieving the synergistic reduction of air pollutants and carbon emissions.

Investment decisions on carbon capture utilization and storage retrofit of Chinese coal-fired power plants based on real option and source-sink matching models

Carbon Capture Utilization and Storage (CCUS) is the only technological option for decarbonizing existing coal-fired power plants (CFPPs) deeply, yet its current scale is far from the level required to meet global climate goals. How carbon price can facilitate CCUS decarbonization of CFPPs in China is a great concern. This study couples a CCUS source-sink matching optimization model covering onshore and offshore geological storages with a trinomial-tree real options model, by which the Chinese critical carbon prices for CCUS investment at different emission reduction potentials are quantified. The results show that when the carbon price reaches 100, 200, and 400 CNY/t, then 24, 28, and 314 GW of CFPPs will enable to invest in CCUS immediately, achieving cumulative 1.8, 2.1, and 24.3 GtCO2 emission reductions over their remaining lifetime. To meet the global warming 2 °C target constraint on China's power sector, the carbon price need to reach 370 CNY/t.

How carbon emission prices accelerate net zero: Evidence from China's coal-fired power plants

China produced over half the world's coal-fired power capacity. Using a recent and comprehensive dataset of 1269 Chinese coal-fired power plants from 2009 to 2019, this paper provides empirical evidence of the impact of China's carbon trading pilot program on emissions regulation. Results show the significant potential for emissions intensity reduction due to increasing carbon prices, especially for low-risk, low-efficiency but high-cost plants, particularly those in China's midland and western regions. Rising marginal abatement costs and accelerated depreciation from carbon prices may encourage utilities to retire high-emission power plants sooner than originally planned, leading to lower emissions intensity. The average retirement years of China's power plants can be shortened by 1.8001 and 1.6862 years under R2CUT and R2LUMP scenarios, respectively, as Cao et al. (2016). This study offers new insights into the impact of carbon prices on power plants and has important policy implications.

Impact of ultra-low emission retrofitting on partitioning and emission behavior of chromium in a Chinese coal-fired power plant.

Due to its low vapor pressure, chromium (Cr) mostly emitted as fly ash particles (especially PM2.5) into environment in coal-fired power plants (CFPPs). The ultra-low emission (ULE) control technologies used in current CFPPs may be beneficial to reducing both the regular pollutants and hazardous trace elements (e.g., Cr), but the insight into the removal efficiency of Cr by different upgrading air pollution cleaning devices (APCDs) and the environmental stability of the Cr-bearing wastes produced from those APCDs in the ULE CFPPs has rarely reported. This study investigated and compared the distribution and emission characteristics of Cr in a Chinese CFPP before and after ULE, and the leaching behavior of Cr after ULE retrofitting in combustion byproducts was also revealed. The results showed that Cr was primarily captured in bottom and fly ashes (80.85%), followed by gypsum (0.02%) and sludge from wet electrostatic precipitator (WESP) (4.52×10-4%), with only 3.02×10-8% emitted into the atmosphere. Additional WESP had a large removal efficiency of Cr with the value of 92.04%, and the overall Cr removal efficiency of selective catalytic reduction (SCR) equipment, electrostatic precipitator (ESP), wet flue gas desulphurization (WFGD) system, and WESP equipped after ULE retrofitting was 99.99%. Notably, although the mass percentage of Cr in WESP sludge was negligible, the concentration of Cr in WESP sludge was 324.04mg/kg. The leaching concentrations of Cr in combustion byproducts were in the descending order: fly ash>WESP sludge>bottom ash>gypsum. The atmospheric emission factor of Cr in the studied power plant was 1.08mg/t coal, which was significantly lower than those of the CFPPs before ULE retrofitting. Therefore, the ULE retrofitting for CFPP was beneficial to reduce Cr emissions. More attention should be paid to the subsequent processing problem of solid combustion byproducts, especially the WESP sludge.

Technology development and cost analysis of multiple pollutant abatement for ultra-low emission coal-fired power plants in China

The implementation of ultra-low emission (ULE) limits (SO2: 35 mg/m3, NOx: 50 mg/m3, PM: 10 mg/m3) promoted the development of flue gas treatment technologies in China. Pollutant control technology development for Chinese coal-fired power plants was summarized and an analysis of the applicability and cost of pollutant control technologies was conducted. Detailed data were collected from 30 ultra-low emission coal-fired units across China. Based on a cost analysis model, the average unit power generation incremental costs were 0.0144 and 0.0095 CNY/(kW·hr) for SO2 and NOx control technologies, respectively. The unit power generation incremental cost of twin spray tower technology was 7.2% higher than that of dual-loop spray tower technology. The effect of key parameters on operating cost was analyzed. The unit power generation incremental cost increased because of increments in the electricity price for SO2 control technology and the price of the reductant in NOx control technology. With high sulfur content or NOx concentration, the unit power generation incremental cost caused by pollutant control increased, whereas the unit pollutant abatement cost decreased. However, the annual operating hours or load increased, thereby leading to a decline in unit power generation incremental cost and unit pollutant abatement cost.

Arsenic emission and distribution characteristics in the ultra-low emission coal-fired power plant.

The characteristics of arsenic emission and distribution of a typical Chinese coal-fired power plant renovated with ultra-low emission technique have been studied. The results showed that arsenic concentration in coal was 5.72 mg/kg, and the arsenic emissions in fly ash, bottom ash, gypsum, flue gas, and wastewater were 489.12 g/h, 5.15 g/h, 1.14 g/h, 0.46 g/h, and 0.03 g/h, respectively, corresponding to the proportion of arsenic in fly ash, bottom ash, gypsum, flue gas, and wastewater of 98.63%, 1.04%, 0.23%, 0.09%, and 0.01%, respectively. About 87.61% of the gaseous arsenic was absorbed by catalysts used for selective catalytic reduction (SCR). Low-low temperature electrostatic precipitator (LLT-ESP) plays a key role in decreasing particulate arsenic. Wet flue gas desulfurization (WFGD) has positive effects on absorbing both gaseous and particulate arsenic. The removal efficiencies across the air pollution control devices follow the order of LLT-ESP > WFGD > SCR. The LLT-ESP can achieve a significant arsenic removal efficiency of 99.94%, resulting in quite low arsenic emission to the atmosphere. According to the calculated arsenic emission factor, the total emission amount of arsenic to the atmosphere from all Chinese coal-fired stations with ultra-low emission control technique in 2020 is estimated to be about 9.67-11.59 tons/year.

Ready-to-implement low-carbon retrofit of coal-fired power plants in China: Optimal scenarios selection based on sludge and photovoltaic utilization

Currently the flexible demand for high proportion penetration of renewable energy depends on coal-fired units (CFUs), and the large-scale phase-out of CFUs in a short time is not realistic in China. Due to urban expansion, approximately 458 Chinese coal-fired power plants (CFPPs) are now located in cities. Limited by space, urban CFUs face difficulty in becoming equipped with carbon capture and storage systems. This presents a sizeable challenge for the low-carbon transition of urban CFPPs and carbon neutral processes. Here, we present a ready-to-implement method to reduce the carbon emission of CFPPs in limited space: roof photovoltaic-assisted power generation combined with sludge co-combustion for coal-fired power generation systems (PVSCs). We also consider nonurban CFPPs with the method of roof photovoltaic-assisted power generation (PVs) only. Based on remaining life cycle analysis, we find that the PVSCs could save 28.47 Mt of coal, reduce CO2 emissions by 69.76 Mt, treat 125.70 Mt of sludge, and also generate 12.08 billion RMB worth of electricity revenue per year. In addition, our scenario analysis shows that PVSCs are more profitable when choosing an urban CFU with a remaining life of more than 12 years and while the sludge treatment subsidy is set at 100 RMB t−1. Under strict and lenient CFU decommissioning policies, CFUs with a remaining life of between 19 and 30 years and between 13 and 24 years should be selected for PVs, respectively. Thus, we conclude that PVSCs can not only generate economic benefits but also facilitate carbon reduction and solid waste treatment.

Identification of potential CCUS clusters and its pipeline network optimization in China

Climate change is a huge challenge facing the world. Carbon Capture, Utilization and Storage (CCUS) is an important technology that is expected to ensure the continued safe and large-scale use of fossil energy under the pressure of climate change in China. However, the current CCUS project has a large initial investment, and it is difficult to realize the commercialization of CCUS technology. The development of CCUS cluster centers can effectively reduce the overall investment of CCUS projects, which is the development trend of CCUS projects. This study identified 20 coal-fired power plant cluster centers and 6 oil and gas field gathering and transportation centers by utilizing Chinese coal-fired power plant data and oil and gas field data. Finally, the CO2 pipe network between the cluster centers is planned. This study provides data and research methods for identifying potential CCUS clusters and storage and transportation centers in China. It can provide a theoretical reference for further research on the matching site selection of CO2 transport pipelines and CO2 sources and sinks in China.

Carbon efficiency and abatement cost of China's coal-fired power plants

In this paper, we propose a new model to investigate the carbon efficiency and carbon abatement cost of coal-fired power plants in China based on the directional distance function with endogenous directional vectors (DVs). We further decompose the change of carbon abatement cost into two contributing factors, i.e., input changes and technical change. The empirical analysis is based on a recent panel dataset comprising 616 Chinese coal-fired power plants from 2011 to 2012. The results show substantial potential for carbon performance improvement in China's coal-fired power plants, with higher carbon efficiency (CE) and lower carbon abatement cost (CAC) associated with non-state-owned enterprises. The decomposition analysis shows that the change in carbon abatement cost is mainly attributed to technical change. However, imposing DVs exogenously can get the opposite results and have a significant impact on the distributions of the estimated results. The findings of this paper provide new insights for better understanding the recent dynamics of the carbon performance of China's coal-fired power plants and have important policy implications.

Distribution and emissions of trace elements in coal-fired power plants after ultra-low emission retrofitting

Various hazardous trace elements emitted from anthropogenic activities are attracting increasing public awareness. This study comprehensively explored the distribution and emissions of trace elements in coal-fired power plants (CFPPs) after ultra-low emission retrofitting by conducting field experiments, literature surveys, and model calculations. High levels of volatile Hg and semi-volatile As/Pb were mainly observed in fly ash and gypsum (96.6%–98.5%), while the proportion of non-volatile Cr in bottom ash was 9.23%. The Hg and As/Pb removal efficiencies were remarkably improved by ultra-low emission retrofitting, increasing by 5.67% and 2.08%/2.63%, respectively. However, ULE retrofitting only slightly affected (0.17%) non-volatile elements. These improvements were mainly attributed to the low-low-temperature electrostatic precipitator. Owing to the enhanced particle-capturing efficiencies, the concentrations of trace elements in the emitted gas of the tested CFPPs were low, ranging from 0.21–1.50 μg/m3, but accounted for a high proportion of the gas phase (61.8%–100%). Based on the national database of coal quality and their behaviour in CFPPs, we found that most of the concentrations of trace elements emitted from Chinese CFPPs were significantly lower than the internationally existing emission limits. However, owing to the skewed distribution characteristics of the emitted concentrations, we suggest issuing or revising the corresponding emission limits and improving the control of intense trace element pollution in China.

Optimization of Chinese coal-fired power plants for cleaner production using Bayesian network

Concern over the influence of cleaner production (CP) transformation on the industrial enterprises has increased in recent years. This research evaluated each process efficiency that enabled entrepreneurs to choose optional ones that previously executed the whole procedure in CP transformation in industry. The risk of invest (time and cost) for each step of CP transformation was ranked using Bayesian network. Datasets from case study of coal fired power plants were simulated using a method of procedure simulation, Design Structure Matrix (DSM), which sought to be prepared for Bayesian network learning. The procedure simulation was based on relationships that each CP transformation step has with each other achieved from experts and experiences. The research gave theoretical guidance and an operable method to industrial entrepreneurs for arranging CP transformation steps and allow them to separate the whole procedure into several stages if inconsistent with budget. Findings indicate that the science and technology categories are preferred for high efficiency in the coal fired power plant CP transformation case.

The characteristics of arsenic in Chinese coal-fired power plant flue gas desulphurisation gypsum

Flue gas desulphurization (FGD) gypsum had broad application prospects in soil, but the trace heavy metals in FGD gypsum directly determine the severity of secondary pollution. In this work, we focused on arsenic in FGD gypsum for 70 samples from Chinese 20 provinces, investigating the characteristics of distribution and leaching by total contents, fractions, leaching tests, and species, and identifying arsenic mode of occurrence and possible risk for FGD gypsum applications. The result showed arsenic was generally approximately 15 mg/kg in Chinese FGD gypsum, and had an obvious geographical distribution by samples from different areas. Leaching tests showed a lower ability of arsenic release in short-term leaching as well as a large potential leaching risk by the sustained release of arsenic in long-term leaching for high-level arsenic FGD gypsum. X-ray photoelectron spectroscopy showed arsenic in FGD gypsum was mainly present as As(III), which has a higher toxicity. Based on our results, with regard of arsenic, most FGD gypsum is a safe material for soil application, but we did notice the potential risk of arsenic release due to long-term leaching and the content of arsenite.

Study on operation status of SCR denitration system in Chinese coal-fired power plants

Since the beginning of the 12th Five-Year Plan, coal-fired power plants have carried out large-scale denitration and ultra-low emission transformation in China, among which SCR denitration technology is the most widely used. However, some hidden problems in the process of project implementation have gradually emerged after operation due to various factors, such as the centralized reconstruction task, lack of technical experience, inadequate quality control of main equipment, uneven quality of denitration catalysts, and insufficient operation and maintenance experience of power generation enterprises. In this context, the future direction of SCR denitration operation and maintenance management is proposed after a systematic summarization and analysis of the operation status of SCR denitration system in recent years to provide reference for subsequent work.

Variation characteristics of final size-segregated PM emissions from ultralow emission coal-fired power plants in China

The ultralow emission (ULE) retrofits for Chinese coal-fired power plants (CFPPs) are nearing completion. Large-scale and rapid retrofits have resulted in significant changes in the emission level and characteristics of particulate matter (PM). To investigate the variation characteristics of final three size fractions PM (PM2.5, PM10−2.5, PM>10) emissions, we conducted field tests at the outlets of wet flue gas desulfurization (WFGD) and wet electrostatic precipitator (WESP) by a pair of two-stage virtual impactors in eight representative ULE CFPPs. Our results indicate that, after WESP installations, the mass concentrations of final PM are significantly reduced and those of the final total ions and elements decrease as most individual chemical compositions are reduced. WESP presents an excellent removal performance for large particle sizes and high PM concentrations. SO42− is the major ionic component at both the outlets of WFGD and WESP, and its proportion in total ions is reduced to some extent through WESP. Furthermore, the average mass contents of SO42− and most elements in PM2.5 are significantly lower than those in PM10−2.5 and PM>10 whether at the WFGD-outlets or WESP-outlets. By comparison, chemical profiles of PM have substantially changed after ULE retrofits, and those after WFGD (e.g., sulfate, Zn, Pb, and Cu) have also changed relative to existing data. The end-tail emission factors (EFs) of PM2.5, PM10, and PMtotal under the typical ULE technical routes of WESP are calculated in time, and the corresponding EFs are in the range of 2.82–8.97, 15.7–27.6, and 38.6–61.7 g t−1, respectively. We believe the latest detailed PM EFs and the associated chemical profiles provided in this study are more representative of the current emission situations of Chinese CFPPs.