Marine carbon sequestration is an important component of carbon dioxide capture, utilization and storage(CCUS) technology. It is crucial for achieving carbon peaking and carbon neutralization in China. However, CO_(2)...Marine carbon sequestration is an important component of carbon dioxide capture, utilization and storage(CCUS) technology. It is crucial for achieving carbon peaking and carbon neutralization in China. However, CO_(2) leakage may lead to seabed geological disasters and threaten the safety of marine engineering. Therefore, it is of great significance to study the safety monitoring technology of marine carbon sequestration.Zhanjiang is industrially developed and rich in carbon sources. Owing to the good physical properties and reservoirs and trap characteristics,Zhanjiang has huge storage potential. This paper explores the disaster mechanism associated with CO_(2) leakage in marine carbon sequestration areas. Based on the analysis of the development of Zhanjiang industry and relevant domestic monitoring technologies, several suggestions for safety monitoring of marine carbon sequestration are proposed: application of offshore aquaculture platforms, expansion and application of ocean observation networks, carbon sequestration safety monitoring and sensing system. Intended to build a comprehensive and multi-level safety monitoring system for marine carbon sequestration, the outcome of this study provides assistance for the development of marine carbon sequestration in China's offshore areas.展开更多
Important first phases in the process of implementing CO2 subsurface and ocean storage projects include selecting of best possible location(s) for CO2 storage, and site selection evaluation. Sites must fulfill a numbe...Important first phases in the process of implementing CO2 subsurface and ocean storage projects include selecting of best possible location(s) for CO2 storage, and site selection evaluation. Sites must fulfill a number of criteria that boil down to the following basics: they must be able to accept the desired volume of CO2 at the rate at which it is supplied from the CO2 source(s);they must as well be safe and reliable;and must comply with regulatory and other societal requirements. They also must have at least public acceptance and be based on sound financial analysis. Site geology;hydrogeological, pressure, and geothermal regimes;land features;location, climate, access, etc. can all be refined from these basic criteria. In addition to aiding in site selection, site characterization is essential for other purposes, such as foreseeing the fate and impacts of the injected CO2, and informing subsequent phases of site development, including design, permitting, operation, monitoring, and eventual abandonment. According to data from the IEA, in 2022, emissions from Africa and Asias emerging markets and developing economies, excluding Chinas, increased by 4.2%, which is equivalent to 206 million tonnes of CO2 and were higher than those from developed economies. Coal-fired power generation was responsible for more than half of the rise in emissions that were recorded in the region. The difficulty of achieving sustainable socio-economic progress in the developing countries is entwined with the work of reducing CO2 emissions, which is a demanding project for the economy. Organisations from developing countries, such as Bangladesh, Cameroon, India, and Nigeria, have formed partnerships with organisations in other countries for lessons learned and investment within the climate change arena. The basaltic rocks, coal seams, depleted oil and gas reservoirs, soils, deep saline aquifers, and sedimentary basins that developing countries (Bangladesh, Cameroon, India, and Nigeria etc.) possess all contribute to the individual countrys significant geological sequestration potential. There are limited or no carbon capture and storage or clean development mechanism projects running in these countries at this time. The site selection and characterization procedure are not complete without an estimate of the storage capacity of a storage location. Estimating storage capacity relies on volumetric estimates because a site must accept the planned volume of CO2 during the active injection period. As more and more applications make use of site characterization, so too does the body of written material on the topic. As the science of CO2 storage develops, regulatory requirements are implemented, field experience grows, and the economics of CO2 capture and storage improve, so too will site selection and characterisation change.展开更多
Carbon dioxide(CO_(2))is the primary greenhouse gas contributing to anthropogenic climate change which is associated with human activities.The majority of CO_(2) emissions are results of the burning of fossil fuels fo...Carbon dioxide(CO_(2))is the primary greenhouse gas contributing to anthropogenic climate change which is associated with human activities.The majority of CO_(2) emissions are results of the burning of fossil fuels for energy,as well as industrial processes such as steel and cement production.Carbon capture,utilization,and storage(CCUS)is a sustainable technology promising in terms of reducing CO_(2) emissions that would otherwise contribute to climate change.From this perspective,the discussion on carbon capture focuses on chemical absorption technology,primarily due to its commercialization potential.The CO_(2) absorptive capacity and absorption rate of various chemical solvents have been summarized.The carbon utilization focuses on electrochemical conversion routes converting CO_(2) into potentially valuable chemicals which have received particular attention in recent years.The Faradaic conversion efficiencies for various CO_(2) reduction products are used to describe efficiency improvements.For carbon storage,successful deployment relies on a better understanding of fluid mechanics,geomechanics,and reactive transport,which are discussed in details.展开更多
Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological lev...Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological level,each country should build a carbon-neutral plan based on its national conditions.Compared with other major developed countries(e.g.,Germany,the United States and Japan),China's carbon neutrality has much bigger challenges,including a heavy and time-pressured carbon reduction task and the current energy structure that is over-dependent on fossil fuels.Here we provide a comprehensive review of the status and prospects of the key technologies for low-carbon,near-zero carbon,and negative carbon emissions.Technological innovations associated with coal,oil-gas and hydrogen industries and their future potential in reducing carbon emissions are particularly explained and assessed.Based on integrated analysis of international experience from the world's major developed countries,in-depth knowledge of the current and future technologies,and China's energy and ecological resources potential,five lessons for the implementation of China's carbon neutrality are proposed:(1)transformation of energy production pattern from a coal-dominated pattern to a diversified renewable energy pattern;(2)renewable power-to-X and large-scale underground energy storage;(3)integration of green hydrogen production,storage,transport and utilization;(4)construction of clean energy systems based on smart sector coupling(ENSYSCO);(5)improvement of ecosystem carbon sinks both in nationwide forest land and potential desert in Northwest China.This paper provides an international perspective for a better understanding of the challenges and opportunities of carbon neutrality in China,and can serve as a theoretical foundation for medium-long term carbon neutral policy formulation.展开更多
The risk of gas leakage due to geological flaws in offshore carbon capture, utilization, and storage, as well as leakage from underwater oil or gas pipelines, highlights the need for underwater gas leakage monitoring ...The risk of gas leakage due to geological flaws in offshore carbon capture, utilization, and storage, as well as leakage from underwater oil or gas pipelines, highlights the need for underwater gas leakage monitoring technology. Remotely operated vehicles(ROVs) and autonomous underwater vehicles(AUVs) are equipped with high-resolution imaging sonar systems that have broad application potential in underwater gas and target detection tasks. However, some bubble clusters are relatively weak scatterers, so detecting and distinguishing them against the seabed reverberation in forward-looking sonar images are challenging. This study uses the dual-tree complex wavelet transform to extract the image features of multibeam forward-looking sonar. Underwater gas leakages with different flows are classified by combining deep learning theory. A pool experiment is designed to simulate gas leakage, where sonar images are obtained for further processing. Results demonstrate that this method can detect and classify underwater gas leakage streams with high classification accuracy. This performance indicates that the method can detect gas leakage from multibeam forward-looking sonar images and has the potential to predict gas leakage flow.展开更多
In the context of carbon capture,utilization,and storage,the high-value utilization of carbon storage presents a significant challenge.To address this challenge,this study employed the bipolar membrane electrodialysis...In the context of carbon capture,utilization,and storage,the high-value utilization of carbon storage presents a significant challenge.To address this challenge,this study employed the bipolar membrane electrodialysis integrated with carbon utilization technology to prepare Na_(2)CO_(3)products using simulated seawater concentrate,achieving simultaneous saline wastewater utilization,carbon storage and high-value production of Na_(2)CO_(3).The effects of various factors,including concentration of simulated seawater concentrate,current density,CO_(2)aeration rate,and circulating flow rate of alkali chamber,on the quality of Na_(2)CO_(3)product,carbon sequestration rate,and energy consumption were investigated.Under the optimal condition,the CO_(3)^(2-)concentration in the alkaline chamber reached a maximum of 0.817 mol/L with 98 mol%purity.The resulting carbon fixation rate was 70.50%,with energy consumption for carbon sequestration and product production of 5.7 k Whr/m^(3)CO_(2)and1237.8 k Whr/ton Na_(2)CO_(3),respectively.This coupling design provides a triple-win outcome promoting waste reduction and efficient utilization of resources.展开更多
Geothermal energy is a kind of renewable,sustainable and clean energy resource.Geothermal energy is abundant in carbonate reservoirs.However,low matrix permeability limits its exploitation.The super-critical carbon di...Geothermal energy is a kind of renewable,sustainable and clean energy resource.Geothermal energy is abundant in carbonate reservoirs.However,low matrix permeability limits its exploitation.The super-critical carbon dioxide(SC-CO_(2))jet fracturing is expected to efficiently stimulate the carbonate geothermal reservoirs and achieve the storage of CO_(2) simultaneously.In this paper,we established a transient seepage and fluid-thermo-mechanical coupled model to analyze the impact performance of sc-CO_(2) jet fracturing.The mesh-based parallel code coupling interface was employed to couple the fluid and solid domains by exchanging the data through the mesh interface.The physical properties change of sC-CO_(2) with temperature were considered in the numerical model.Results showed that SC-CO_(2) jet frac-turing is superior to water-jet fracturing with respect to jetting velocity,particle trajectory and pene-trability.Besides,stress distribution on the carbonate rock showed that the tensile and shear failure would more easily occur by SC-CO_(2) jet than that by water jet.Moreover,pressure and temperature control the jet field and seepage field of sC-CO_(2) simultaneously.Increasing the jet temperature can effectively enhance the impingement effect and seepage process by decreasing the viscosity and density of SC-CO_(2).The key findings are expected to provide a theoretical basis and design reference for applying SC-CO_(2) jet fracturing in carbonate geothermal reservoirs.展开更多
Carbon capture,utilization,and storage(CCUS)is estimated to contribute substantial CO_(2)emission reduction to carbon neutrality in China.There is yet a large gap between such enormous demand and the current capacity,...Carbon capture,utilization,and storage(CCUS)is estimated to contribute substantial CO_(2)emission reduction to carbon neutrality in China.There is yet a large gap between such enormous demand and the current capacity,and thus a sound enabling environment with sufficient policy support is imperative for CCUS development.This study reviewed 59 CCUS-related policy documents issued by the Chinese government as of July 2022,and found that a supporting policy framework for CCUS is taking embryonic form in China.More than ten departments of the central government have involved CCUS in their policies,of which the State Council,the National Development and Reform Commission(NDRC),the Ministry of Science and Technology(MOST),and the Ministry of Ecological Environment(MEE)have given the greatest attention with different focuses.Specific policy terms are further analyzed following the method of content analysis and categorized into supply-,environment-and demand-type policies.The results indicate that supply-type policies are unbalanced in policy objectives,as policy terms on technology research and demonstration greatly outnumber those on other objectives,and the attention to weak links and industrial sectors is far from sufficient.Environment-type policies,especially legislations,standards,and incentives,are inadequate in pertinence and operability.Demand-type policies are absent in the current policy system but is essential to drive the demand for the CCUS technology in domestic and foreign markets.To meet the reduction demand of China's carbon neutral goal,policies need to be tailored according to needs of each specific technology and implemented in an orderly manner with well-balanced use on multiple objectives.展开更多
Thecoal-to-liquidcoupledwithcarbon capture,utilization,and storage technology has the potential to reduce CO_(2)emissions,but its carbon footprint and cost assessment are still insufficient.In this paper,coal mining t...Thecoal-to-liquidcoupledwithcarbon capture,utilization,and storage technology has the potential to reduce CO_(2)emissions,but its carbon footprint and cost assessment are still insufficient.In this paper,coal mining to oil production is taken as a life cycle to evaluate the carbon footprint and levelized costs of direct-coal-toliquid and indirect-coal-to-liquid coupled with the carbon capture utilization and storage technology under three scenarios:non capture,process capture,process and public capture throughout the life cycle.The results show that,first,the coupling carbon capture utilization and storage technology can reduce CO_(2)footprint by 28%-57%from 5.91 t CO_(2)/t:oil of direct-coal-to-liquid and 24%-49%from 7.10 t CO_(2)/t:oil of indirect-coal-to-liquid.Next,the levelized cost of direct-coal-to-liquid is 648-1027$/t of oil,whereas that of indirect-coal-to-liquid is 653-1065$/t of oil.When coupled with the carbon capture utilization and storage technology,the levelized cost of direct-coalto-liquid is 285-1364$/t of oil,compared to 1101-9793/t of oil for indirect-coal-to-liquid.Finally,sensitivity analysis shows that CO_(2)transportation distance has the greatest impact on carbon footprint,while coal price and initial investment cost significantly affect the levelized cost ofcoal-to-liquid.展开更多
文摘Marine carbon sequestration is an important component of carbon dioxide capture, utilization and storage(CCUS) technology. It is crucial for achieving carbon peaking and carbon neutralization in China. However, CO_(2) leakage may lead to seabed geological disasters and threaten the safety of marine engineering. Therefore, it is of great significance to study the safety monitoring technology of marine carbon sequestration.Zhanjiang is industrially developed and rich in carbon sources. Owing to the good physical properties and reservoirs and trap characteristics,Zhanjiang has huge storage potential. This paper explores the disaster mechanism associated with CO_(2) leakage in marine carbon sequestration areas. Based on the analysis of the development of Zhanjiang industry and relevant domestic monitoring technologies, several suggestions for safety monitoring of marine carbon sequestration are proposed: application of offshore aquaculture platforms, expansion and application of ocean observation networks, carbon sequestration safety monitoring and sensing system. Intended to build a comprehensive and multi-level safety monitoring system for marine carbon sequestration, the outcome of this study provides assistance for the development of marine carbon sequestration in China's offshore areas.
文摘Important first phases in the process of implementing CO2 subsurface and ocean storage projects include selecting of best possible location(s) for CO2 storage, and site selection evaluation. Sites must fulfill a number of criteria that boil down to the following basics: they must be able to accept the desired volume of CO2 at the rate at which it is supplied from the CO2 source(s);they must as well be safe and reliable;and must comply with regulatory and other societal requirements. They also must have at least public acceptance and be based on sound financial analysis. Site geology;hydrogeological, pressure, and geothermal regimes;land features;location, climate, access, etc. can all be refined from these basic criteria. In addition to aiding in site selection, site characterization is essential for other purposes, such as foreseeing the fate and impacts of the injected CO2, and informing subsequent phases of site development, including design, permitting, operation, monitoring, and eventual abandonment. According to data from the IEA, in 2022, emissions from Africa and Asias emerging markets and developing economies, excluding Chinas, increased by 4.2%, which is equivalent to 206 million tonnes of CO2 and were higher than those from developed economies. Coal-fired power generation was responsible for more than half of the rise in emissions that were recorded in the region. The difficulty of achieving sustainable socio-economic progress in the developing countries is entwined with the work of reducing CO2 emissions, which is a demanding project for the economy. Organisations from developing countries, such as Bangladesh, Cameroon, India, and Nigeria, have formed partnerships with organisations in other countries for lessons learned and investment within the climate change arena. The basaltic rocks, coal seams, depleted oil and gas reservoirs, soils, deep saline aquifers, and sedimentary basins that developing countries (Bangladesh, Cameroon, India, and Nigeria etc.) possess all contribute to the individual countrys significant geological sequestration potential. There are limited or no carbon capture and storage or clean development mechanism projects running in these countries at this time. The site selection and characterization procedure are not complete without an estimate of the storage capacity of a storage location. Estimating storage capacity relies on volumetric estimates because a site must accept the planned volume of CO2 during the active injection period. As more and more applications make use of site characterization, so too does the body of written material on the topic. As the science of CO2 storage develops, regulatory requirements are implemented, field experience grows, and the economics of CO2 capture and storage improve, so too will site selection and characterisation change.
基金the National Natural Science Foun-dation of China(51836006).
文摘Carbon dioxide(CO_(2))is the primary greenhouse gas contributing to anthropogenic climate change which is associated with human activities.The majority of CO_(2) emissions are results of the burning of fossil fuels for energy,as well as industrial processes such as steel and cement production.Carbon capture,utilization,and storage(CCUS)is a sustainable technology promising in terms of reducing CO_(2) emissions that would otherwise contribute to climate change.From this perspective,the discussion on carbon capture focuses on chemical absorption technology,primarily due to its commercialization potential.The CO_(2) absorptive capacity and absorption rate of various chemical solvents have been summarized.The carbon utilization focuses on electrochemical conversion routes converting CO_(2) into potentially valuable chemicals which have received particular attention in recent years.The Faradaic conversion efficiencies for various CO_(2) reduction products are used to describe efficiency improvements.For carbon storage,successful deployment relies on a better understanding of fluid mechanics,geomechanics,and reactive transport,which are discussed in details.
基金supported by the Henan Institute for Chinese Development Strategy of Engineering&Technology(Grant No.2022HENZDA02)by the Science&Technology Department of Sichuan Province Project(Grant No.2021YFH0010).
文摘Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological level,each country should build a carbon-neutral plan based on its national conditions.Compared with other major developed countries(e.g.,Germany,the United States and Japan),China's carbon neutrality has much bigger challenges,including a heavy and time-pressured carbon reduction task and the current energy structure that is over-dependent on fossil fuels.Here we provide a comprehensive review of the status and prospects of the key technologies for low-carbon,near-zero carbon,and negative carbon emissions.Technological innovations associated with coal,oil-gas and hydrogen industries and their future potential in reducing carbon emissions are particularly explained and assessed.Based on integrated analysis of international experience from the world's major developed countries,in-depth knowledge of the current and future technologies,and China's energy and ecological resources potential,five lessons for the implementation of China's carbon neutrality are proposed:(1)transformation of energy production pattern from a coal-dominated pattern to a diversified renewable energy pattern;(2)renewable power-to-X and large-scale underground energy storage;(3)integration of green hydrogen production,storage,transport and utilization;(4)construction of clean energy systems based on smart sector coupling(ENSYSCO);(5)improvement of ecosystem carbon sinks both in nationwide forest land and potential desert in Northwest China.This paper provides an international perspective for a better understanding of the challenges and opportunities of carbon neutrality in China,and can serve as a theoretical foundation for medium-long term carbon neutral policy formulation.
文摘The risk of gas leakage due to geological flaws in offshore carbon capture, utilization, and storage, as well as leakage from underwater oil or gas pipelines, highlights the need for underwater gas leakage monitoring technology. Remotely operated vehicles(ROVs) and autonomous underwater vehicles(AUVs) are equipped with high-resolution imaging sonar systems that have broad application potential in underwater gas and target detection tasks. However, some bubble clusters are relatively weak scatterers, so detecting and distinguishing them against the seabed reverberation in forward-looking sonar images are challenging. This study uses the dual-tree complex wavelet transform to extract the image features of multibeam forward-looking sonar. Underwater gas leakages with different flows are classified by combining deep learning theory. A pool experiment is designed to simulate gas leakage, where sonar images are obtained for further processing. Results demonstrate that this method can detect and classify underwater gas leakage streams with high classification accuracy. This performance indicates that the method can detect gas leakage from multibeam forward-looking sonar images and has the potential to predict gas leakage flow.
基金supported by the Central Guidance on Local Science and Technology Development Fund of Hebei Province(No.226Z3102G)the Fundamental Research Funds of Hebei University of Technology(No.JBKYTD2001)the Science Research Project of Hebei Education Department(No.QN2022089)。
文摘In the context of carbon capture,utilization,and storage,the high-value utilization of carbon storage presents a significant challenge.To address this challenge,this study employed the bipolar membrane electrodialysis integrated with carbon utilization technology to prepare Na_(2)CO_(3)products using simulated seawater concentrate,achieving simultaneous saline wastewater utilization,carbon storage and high-value production of Na_(2)CO_(3).The effects of various factors,including concentration of simulated seawater concentrate,current density,CO_(2)aeration rate,and circulating flow rate of alkali chamber,on the quality of Na_(2)CO_(3)product,carbon sequestration rate,and energy consumption were investigated.Under the optimal condition,the CO_(3)^(2-)concentration in the alkaline chamber reached a maximum of 0.817 mol/L with 98 mol%purity.The resulting carbon fixation rate was 70.50%,with energy consumption for carbon sequestration and product production of 5.7 k Whr/m^(3)CO_(2)and1237.8 k Whr/ton Na_(2)CO_(3),respectively.This coupling design provides a triple-win outcome promoting waste reduction and efficient utilization of resources.
基金the National Key R&D Program of China(No.2019YFB1504102).
文摘Geothermal energy is a kind of renewable,sustainable and clean energy resource.Geothermal energy is abundant in carbonate reservoirs.However,low matrix permeability limits its exploitation.The super-critical carbon dioxide(SC-CO_(2))jet fracturing is expected to efficiently stimulate the carbonate geothermal reservoirs and achieve the storage of CO_(2) simultaneously.In this paper,we established a transient seepage and fluid-thermo-mechanical coupled model to analyze the impact performance of sc-CO_(2) jet fracturing.The mesh-based parallel code coupling interface was employed to couple the fluid and solid domains by exchanging the data through the mesh interface.The physical properties change of sC-CO_(2) with temperature were considered in the numerical model.Results showed that SC-CO_(2) jet frac-turing is superior to water-jet fracturing with respect to jetting velocity,particle trajectory and pene-trability.Besides,stress distribution on the carbonate rock showed that the tensile and shear failure would more easily occur by SC-CO_(2) jet than that by water jet.Moreover,pressure and temperature control the jet field and seepage field of sC-CO_(2) simultaneously.Increasing the jet temperature can effectively enhance the impingement effect and seepage process by decreasing the viscosity and density of SC-CO_(2).The key findings are expected to provide a theoretical basis and design reference for applying SC-CO_(2) jet fracturing in carbonate geothermal reservoirs.
基金the Cooperative Project of the Chinese Academy of Engineering(Grant No.202001SDZD01).
文摘Carbon capture,utilization,and storage(CCUS)is estimated to contribute substantial CO_(2)emission reduction to carbon neutrality in China.There is yet a large gap between such enormous demand and the current capacity,and thus a sound enabling environment with sufficient policy support is imperative for CCUS development.This study reviewed 59 CCUS-related policy documents issued by the Chinese government as of July 2022,and found that a supporting policy framework for CCUS is taking embryonic form in China.More than ten departments of the central government have involved CCUS in their policies,of which the State Council,the National Development and Reform Commission(NDRC),the Ministry of Science and Technology(MOST),and the Ministry of Ecological Environment(MEE)have given the greatest attention with different focuses.Specific policy terms are further analyzed following the method of content analysis and categorized into supply-,environment-and demand-type policies.The results indicate that supply-type policies are unbalanced in policy objectives,as policy terms on technology research and demonstration greatly outnumber those on other objectives,and the attention to weak links and industrial sectors is far from sufficient.Environment-type policies,especially legislations,standards,and incentives,are inadequate in pertinence and operability.Demand-type policies are absent in the current policy system but is essential to drive the demand for the CCUS technology in domestic and foreign markets.To meet the reduction demand of China's carbon neutral goal,policies need to be tailored according to needs of each specific technology and implemented in an orderly manner with well-balanced use on multiple objectives.
基金the National Natural Science Foundation of China(Grant Nos.72174196 and 71874193)Open Fund of State Key Laboratory of Coal Resources and Safe Mining(China University of Mining and Technology)(Grant Nos.SKLCRSM21KFA05 and SKLCRSM22KFA09)the Fundamental Research Funds for the Central Universities(Grant No.2022JCCXNY02).
文摘Thecoal-to-liquidcoupledwithcarbon capture,utilization,and storage technology has the potential to reduce CO_(2)emissions,but its carbon footprint and cost assessment are still insufficient.In this paper,coal mining to oil production is taken as a life cycle to evaluate the carbon footprint and levelized costs of direct-coal-toliquid and indirect-coal-to-liquid coupled with the carbon capture utilization and storage technology under three scenarios:non capture,process capture,process and public capture throughout the life cycle.The results show that,first,the coupling carbon capture utilization and storage technology can reduce CO_(2)footprint by 28%-57%from 5.91 t CO_(2)/t:oil of direct-coal-to-liquid and 24%-49%from 7.10 t CO_(2)/t:oil of indirect-coal-to-liquid.Next,the levelized cost of direct-coal-to-liquid is 648-1027$/t of oil,whereas that of indirect-coal-to-liquid is 653-1065$/t of oil.When coupled with the carbon capture utilization and storage technology,the levelized cost of direct-coalto-liquid is 285-1364$/t of oil,compared to 1101-9793/t of oil for indirect-coal-to-liquid.Finally,sensitivity analysis shows that CO_(2)transportation distance has the greatest impact on carbon footprint,while coal price and initial investment cost significantly affect the levelized cost ofcoal-to-liquid.