Multi-Pollutant Formation and Control in Pressurized Oxy-Combustion:SO_(x),NO_(x),Particulate Matter,and Mercury

Oxy-combustion is a promising carbon-capture technology,but atmospheric-pressure oxy-combustion has a relatively low net efficiency,limiting its application in power plants.In pressurized oxycombustion(POC),the boiler,air separation unit,flue gas recirculation unit,and CO_(2)purification and compression unit are all operated at elevated pressure;this makes the process more efficient,with many advantages over atmospheric pressure,such as low NO_(x)emissions,a smaller boiler size,and more.POC is also more promising for industrial application and has attracted widespread research interest in recent years.It can produce high-pressure CO_(2)with a purity of approximately 95%,which can be used directly for enhanced oil recovery or geo-sequestration.However,the pollutant emissions must meet the standards for carbon capture,storage,and utilization.Because of the high oxygen and moisture concentrations in POC,the formation of acids via the oxidation and solution of SO_(x)and NO_(x)can be increased,causing the corrosion of pipelines and equipment.Furthermore,particulate matter(PM)and mercury emissions can harm the environment and human health.The main distinction between pressurized and atmospheric-pressure oxy-combustion is the former’s elevated pressure;thus,the effect of this pressure on the pollutants emitted from POC—including SO_(x),NO_(x),PM,and mercury—must be understood,and effective control methodologies must be incorporated to control the formation of these pollutants.This paper reviews recent advances in research on SO_(x),NO_(x),PM,and mercury formation and control in POC systems that can aid in pollutant control in such systems.

Carbon Dioxide Control-Technology for the Future

The world is experiencing global climate change, and most scientists attribute it to the accumulation in the atmosphere of carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. Because of its enormous emission rate, carbon dioxide （CO2） is the main culprit. Almost all the anthropogenic CO2 emissions come from the burning of fossil fuels for electricity, heat, and transportation. Emissions of COg can be reduced by conservation, increased use of renewable energy sources, and increased efficiencies in both the production of electrical power and the transportation sector. Capture of CO2 can be accomplished with wet scrubbing, dry sorption, or biogenic fixation. After CO2 is captured, it must be transported either as a liquid or a supercritical fluid, which realistically can only be accomplished by pipeline or ship. Final disposal of CO2 will either be to underground reservoirs or to the ocean; at present, the underground option seems to be the only viable one. Various strategies and technologies involved with reduction of CO2 emissions and carbon capture and sequestration （CCS） are briefly reviewed in this paper.

Carbon capture and sequestration:The roles of agriculture and soils

Renewable energy as a replacement for fossil fuels is highly desirable,but the reality is that fossil fuels(especially coal and petroleum)will be major sources of global energy for many decades to come.Therefore,carbon capture is vital to reduce release of carbon emissions and other GHG’s to the atmosphere thereby mitigating global warming.This presentation is a review of the role of agriculture and soils in carbon capture.Carbon sequestration in soils is the process of transferring CO2 from the atmosphere into soils through crop residues.Soil carbon sequestration increases with practices long recommended to increase yields,such as no-till,manure application,agroforestry and cover cropping.It is a Win-Win-Win strategy―advancing food security,improving the environment,and mitigating global warming.Carbon enrichment in greenhouse culture is in widespread use and has been adopted by many commercial producers.It results in remarkable increases in yields of flowers and vegetables.Research has shown the same increase in yields of trees and field crops with higher CO2 concentrations.The question is,how can CO2 be applied to field crops to increase yields?Restoration of desertified lands would improve soil quality,increase the pool of C in soils and forests,reduce CO2 emission to the atmosphere,and improve soil quality.Sequestration of additional carbon in soils would reduce CO2 emissions to the atmosphere thus mitigating global warming.Reforestation of forests is important,but real trees have ecological limits.Artificial trees could be used to absorb CO2 from the air any place on the planet,from any source―power plants,vehicles,and all industrial applications.Addition of CO2 in irrigation water could reduce the pH and help restore alkaline soils.Research is needed to further clarify the cost and benefit of many agriculture technologies for capturing and storing carbon.

Reactive Transport Modeling of Long-Term CO2 Sequestration Mechanisms at the Shenhua CCS Demonstration Project,China

Carbon dioxide injection into deep saline aquifers results in a variety of strongly coupled physical and chemical processes. In this study, reactive transport simulations using a 2-D radial model were performed to investigate the fate of the injected CO2, the effect of CO2-water-rock interactions on mineral alteration, and the long-term CO2 sequestration mechanisms of the Liujiagou Formation sandstone at the Shenhua CCS（carbon capture and storage） pilot site of China. Carbon dioxide was injected at a constant rate of 0.1 Mt/year for 30 years, and the fluid flow and geochemical transport simulation was run for a period of 10 000 years by the TOUGHREACT code according to the underground conditions of the Liujiagou Formation. The results show that different trapping phases of CO2 vary with time. Sensitivity analyses indicate that plagioclase composition and chlorite presence are the most significant determinants of stable carbonate minerals and CO2 mineral trapping capacity. For arkosic arenite in the Liujiagou Formation, CO2 can be immobilized by precipitation of ankerite, magnesite, siderite, dawsonite, and calcite for different mineral compositions, with Ca（2＋）, Mg（2＋）, Fe（2＋） and Na＋ provided by dissolution of calcite, albite（or oligoclase） and chlorite. This study can provide useful insights into the geochemistry of CO2 storage in other arkosic arenite（feldspar rich sandstone） formations at other pilots or target sites.

A systemic review of hydrogen supply chain in energy transition

Targeting the net-zero emission(NZE)by 2050,the hydrogen industry is drastically developing in recent years.However,the technologies of hydrogen upstream production,midstream transportation and storage,and downstream utilization are facing obstacles.In this paper,the development of hydrogen industry from the production,transportation and storage,and sustainable economic development perspectives were reviewed.The current challenges and future outlooks were summarized consequently.In the upstream,blue hydrogen is dominating the current hydrogen supply,and an implementation of carbon capture and sequestration(CCS)can raise its cost by 30%.To achieve an economic feasibility,green hydrogen needs to reduce its cost by 75%to approximately 2$/kg at the large scale.The research progress in the midterm sector is still in a preliminary stage,where experimental and theoretical investigations need to be conducted in addressing the impact of embrittlement,contamination,and flammability so that they could provide a solid support for material selection and largescale feasibility studies.In the downstream utilization,blue hydrogen will be used in producing value-added chemicals in the short-term.Over the long-term,green hydrogen will dominate the market owing to its high energy intensity and zero carbon intensity which provides a promising option for energy storage.Technologies in the hydrogen industry require a comprehensive understanding of their economic and environmental benefits over the whole life cycle in supporting operators and policymakers.

Particuology and climate change

The global concern over the greenhouse gas emissions and its effect on global warming and climate change has focused attention on the necessity of carbon dioxide capture and sequestration. There are many processes proposed to capture carbon either before or after combustion and these processes invariably involve investigation and application of traditional particuology. The solids employed are of different sizes, densities, morphologies, and strengths. Their handling, transportation, recirculation, and reactor applications are the essence of ＇particuology＇. Particuology can play an important and vital role in achieving cost-effective removal of carbon and minimize emissions of greenhouse gases. In this paper, the existing and developing carbon capture processes are briefly reviewed and the opportunities for application of particuology are identified. The review was not intended to be exhaustive. It is only in sufficient detail to make connection between particuology and climate change. For immediate and future challenges of reducing global warming and carbon capture and sequestration, innovative reactor design and application of parricuology is imperative. Expertise and innovation in particuology can greatly enhance the speed of development of those technologies and help to achieve cost-effective implementation. Particuology is indeed intimately related to the climate change and global warming.