Efficiency stagnation in global steel production urges joint supply- and demand-side mitigation efforts

Carbon emissions in China's steel industry from a life cycle perspective: Carbon footprint insights

China is the most important steel producer in the world, and its steel industry is one of the most carbon-intensive industries in China. Consequently, research on carbon emissions from the steel industry is crucial for China to achieve carbon neutrality and meet its sustainable global development goals. We constructed a carbon dioxide (CO2) emission model for China's iron and steel industry from a life cycle perspective, conducted an empirical analysis based on data from 2019, and calculated the CO2 emissions of the industry throughout its life cycle. Key emission reduction factors were identified using sensitivity analysis. The results demonstrated that the CO2 emission intensity of the steel industry was 2.33 ton CO2/ton, and the production and manufacturing stages were the main sources of CO2 emissions, accounting for 89.84% of the total steel life-cycle emissions. Notably, fossil fuel combustion had the highest sensitivity to steel CO2 emissions, with a sensitivity coefficient of 0.68, reducing the amount of fossil fuel combustion by 20% and carbon emissions by 13.60%. The sensitivities of power structure optimization and scrap consumption were similar, while that of the transportation structure adjustment was the lowest, with a sensitivity coefficient of less than 0.1. Given the current strategic goals of peak carbon and carbon neutrality, it is in the best interest of the Chinese government to actively promote energy-saving and low-carbon technologies, increase the ratio of scrap steel to steelmaking, and build a new power system.

Metabolomic and Lipidomic Analysis of Manganese-Associated Parkinsonism: a Case-Control Study in Brescia, Italy

Background and Objectives

Excessive Manganese (Mn) exposure is neurotoxic and can cause Mn-Induced Parkinsonism (MnIP), marked by cognitive and motor dysfunction. Although metabolomic and lipidomic research in Parkinsonism (PD) patients exists, it remains limited. This study hypothesizes distinct metabolomic and lipidomic profiles based on exposure status, disease diagnosis, and their interaction.

Methods

We used a case-control design with a 2×2 factorial framework to investigate the metabolomic and lipidomic alterations associated with Mn exposure and their link to PD. The study population of 97 individuals was divided into four groups: non-exposed controls (n=23), exposed controls (n=25), non-exposed with PD (n=26) and exposed with PD (n=23). Cases, defined by at least two cardinal PD features (excluding vascular, iatrogenic, and traumatic origins), were recruited from movement disorder clinics in four hospitals in Brescia, Northern Italy. Controls, free from neurological or psychiatric conditions, were selected from the same hospitals. Exposed subjects resided in metallurgic regions (Val Camonica and Bagnolo Mella) for at least 8 continuous years, while non-exposed subjects lived in low-exposure areas around Lake Garda and Brescia city. We conducted untargeted analyses of metabolites and lipids in whole blood samples using ultra-high-performance liquid chromatography (UHPLC) and mass spectrometry (MS), followed by statistical analyses including Principal Component Analysis (PCA), Partial Least Squares-Discriminant Analysis (PLS-DA), and Two-Way Analysis of Covariance (ANCOVA).

Results

Metabolomic analysis revealed modulation of alanine, aspartate, and glutamate metabolism (Impact=0.05, p=0.001) associated with disease effect; butanoate metabolism (Impact=0.03, p=0.004) with the exposure effect; and vitamin B6 metabolism (Impact=0.08, p=0.03) with the interaction effect. Differential relative abundances in 3-sulfoxy-L-Tyrosine (β=1.12, FDR p<0.001), glycocholic acid (β=0.48, FDR p=0.03), and palmitelaidic acid (β=0.30, FDR p<0.001) were linked to disease, exposure, and interaction effects, respectively. In the lipidome, ferroptosis (Pathway Lipids=11, FDR p=0.03) associated with the disease effect and sphingolipid signaling (Pathway Lipids=9, FDR p=0.04) associated with the interaction effect were significantly altered. Lipid classes triacylglycerols, ceramides, and phosphatidylethanolamines showed differential relative abundances associated with disease, exposure, and interaction effects, respectively.

Discussion

These findings suggest that PD and Mn exposure induce unique metabolomic and lipidomic changes, potentially serving as biomarkers for MnIP and warranting further study.

Uncovering Availability of the Secondary Iron Resources in China: Integrating Material Flow Analysis and Secondary Resources Reserve Assessment

As the largest iron and steel producer, China still cannot meet its demand of iron and steel only through domestic primary supply in the last few decades. Hence, secondary iron resources are increasingly significant in meeting China's iron supply and demand balance. However, the secondary iron resource availability in China and how it impacts the future supply demand balance were still insufficiently discussed. In this work, we developed a material flow analysis and secondary resources reserve assessment (MFA-SRRA) integrated model, assessed secondary iron resources availability, and conducted a supply demand analysis through nine scenarios for irons in China. The results showed that China's secondary iron reserves will increase from 8.9 Gt in 2021 to 14.04 to 19.01 Gt in 2050. With the increasing secondary iron supply, more than 60% of iron ore as a source of steelmaking can be replaced by 2050. Landfills, as a significant reserve of iron but always ignored, will accumulate 1.42-1.51 Gt secondary iron resources by 2050 and should be noticed to be mined and utilized in the future. Last, we suggest that promoting innovation in landfill mining technology and making sustainable material management policies are urgent to prevent these secondary iron resources from becoming real waste.

Achieving health-oriented air pollution control requires integrating unequal toxicities of industrial particles

Protecting human health from fine particulate matter (PM) pollution is the ambitious goal of clean air actions, but current control strategies  largely ignore the role of source-specific PM toxicity. Here, we proposed health-oriented control strategies by integrating the unequal toxic potencies of the most polluting industrial PMs. Iron and steel industry (ISI)-emitted PM2.5 exhibit about one order of magnitude higher toxic potency than those of cement and power industries. Compared with the current mass-based control strategy (prioritizing implementation of ultralow emission standards in the power sector), the proposed health-oriented control strategy (priority control of the ISI sector) could generate 5.4 times higher reduction in population-weighted toxic potency-adjusted PM2.5 exposure among polluting industries in China. Furthermore, the marginal abatement cost per unit of toxic potency-adjusted mass of ISI-emitted PM2.5 is only a quarter of that of the other two sectors under ultralow emission scenarios. We highlight that a health-oriented air pollution control strategy is urgently required to achieve cost-effective reductions in particulate exposure risks.

Global iron and steel plant CO2 emissions and carbon-neutrality pathways

The highly energy-intensive iron and steel industry contributed about 25% (ref. 1) of global industrial CO2 emissions in 2019 and is therefore critical for climate-change mitigation. Despite discussions of decarbonization potentials at national and global levels2-6, plant-specific mitigation potentials and technologically driven pathways remain unclear, which cumulatively determines the progress of net-zero transition of the global iron and steel sector. Here we develop a CO2 emissions inventory of 4,883 individual iron and steel plants along with their technical characteristics, including processing routes and operating details (status, age, operation-years etc.). We identify and match appropriate emission-removal or zero-emission technologies to specific possessing routes, or what we define thereafter as a techno-specific decarbonization road map for every plant. We find that 57% of global plants have 8-24 operational years, which is the retrofitting window for low-carbon technologies. Low-carbon retrofitting following the operational characteristics of plants is key for limiting warming to 2 °C, whereas advanced retrofitting may help limit warming to 1.5 °C. If each plant were retrofitted 5 years earlier than the planned retrofitting schedule, this could lead to cumulative global emissions reductions of 69.6 (±52%) gigatonnes (Gt) CO2 from 2020 to 2050, almost double that of global CO2 emissions in 2021. Our results provide a detailed picture of CO2 emission patterns associated with production processing of iron and steel plants, illustrating the decarbonization pathway to the net-zero-emissions target with the efforts from each plant.

Unlocking Dysprosium Constraints for China's 1.5 °C Climate Target

Some key low-carbon technologies, ranging from wind turbines to electric vehicles, are underpinned by the strong rare-earth-based permanent magnets of the Nd, Pr (Dy)-Fe-Nb type (NdFeB). These NdFeB magnets, which are sensitive to demagnetization with temperature elevation (the Curie point), require the addition of variable amounts of dysprosium (Dy), where an elevation of the Curie point is needed to meet operational conditions. Given that China is the world's largest REE supplier with abundant REE reserves, the impact of an ambitious 1.5 °C climate target on China's Dy supply chain has sparked widespread concern. Here, we explore future trends and innovation strategies associated with the linkage between Dy and NdFeBs under various climate scenarios in China. We find China alone is expected to exhaust the global present Dy reserve within the next 2-3 decades to facilitate the 1.5 °C climate target. By implementing global available innovation strategies, such as material substitution, reduction, and recycling, it is possible to avoid 48%-68% of China's cumulative demand for Dy. Nevertheless, ongoing efforts in REE exploration and production are still required to meet China's growing Dy demand, which will face competition from the United States, European Union, and other countries with ambitious climate targets. Thus, our analysis urges China and those nations to form wider cooperation in REE supply chains as well as in NdFeB innovation for the realization of a global climate-safe future.

Tracking Carbon Flows in China's Iron and Steel Industry

Accurately tracking carbon flows is the first step toward reducing the climate impacts of the iron and steel industry (ISI), which is still lacking in China. In this study, we track carbon flows from coal/mineral mines to end steel users by coupling the cross-process material and energy flow model, point-based emission inventory, and interprovincial trade matrices. In 2020, ISI emitted 2288 Tg of CO2 equivalent (CO2eq, including CH4 and CO2), 96% of which came from energy use and 4% from raw material decomposition. Often overlooked off-gas use and CH4 leakage in coal mines account for 25% of life-cycle emissions. Due to limited scrap resources and a high proportion of pig iron feed, the life-cycle emission intensity of the electric arc furnace (EAF) (1.15 t CO2eq/t steel) is slightly lower than the basic oxygen furnace (BOF) (1.58 t CO2eq/t steel) in China. In addition, over 49% of producer-based emissions are driven by interprovincial coal/coke/steel trade. In particular, nearly all user-based emissions in Zhejiang and Beijing are transferred to steelmaking bases. Therefore, we highlight the need for life-cycle and spatial shifts in user-side carbon management.

Tracing metal footprints via global renewable power value chains

The globally booming renewable power industry has stimulated an unprecedented interest in metals as key infrastructure components. Many economies with different endowments and levels of technology participate in various production stages and cultivate value in global renewable power industry production networks, known as global renewable power value chains (RPVCs), complicating the identification of metal supply for the subsequent low-carbon power generation and demand. Here, we use a multi-regional input-output model (MRIO) combined with a value chain decomposition model to trace the metal footprints (MFs) and value-added of major global economies' renewable power sectors. We find that the MFs of the global renewable power demand increased by 97% during 2005-2015. Developed economies occupy the high-end segments of RPVCs while allocating metal-intensive (but low value-added) production activities to developing economies. The fast-growing demand for renewable power in developed economies or developing economies with upper middle income, particularly China, is a major contributor to the embodied metal transfer increment within RPVCs, which is partly offset by the declining metal intensities in developing economies. Therefore, it is urgent to establish a metal-efficient and green supply chain for upstream suppliers as well as downstream renewable power installers for just transition in the power sector across the globe.

Greenhouse gas emissions from extractive industries in a globalized era

The extractive industry consumes vast amounts of energy and is a major contributor to greenhouse gas (GHG) emissions. However, its climatic impacts have not yet been fully accounted for. In this study, we estimated the GHG emissions from extractive activities globally with a focus on China, and assessed the main emission drivers. In addition, we predicted the Chinese extractive industry emissions in the context of global mineral demand and cycling. As of 2020, GHG emissions from the global extractive industry had reached 7.7 billion tons of CO₂ equivalents (CO₂e), accounting for approximately 15.0% of the global anthropogenic GHG emissions (excluding GHG emissions from land use, land-use change, and forestry activities (LULUCF), with China being the largest emitter, accounting for 3.5% of global emissions. Extractive industry GHG emissions are projected to peak by 2030 or even earlier to achieve low-carbon peak targets. The most critical pathway for reducing GHG emissions in the extractive industry is to control emissions from coal mining. Therefore, reducing methane emissions from mining and washing coal (MWC) should be prioritized.

Global green hydrogen-based steel opportunities surrounding high quality renewable energy and iron ore deposits

The steel sector currently accounts for 7% of global energy-related CO₂ emissions and requires deep reform to disconnect from fossil fuels. Here, we investigate the market competitiveness of one of the widely considered decarbonisation routes for primary steel production: green hydrogen-based direct reduction of iron ore followed by electric arc furnace steelmaking. Through analysing over 300 locations by combined use of optimisation and machine learning, we show that competitive renewables-based steel production is located nearby the tropic of Capricorn and Cancer, characterised by superior solar with supplementary onshore wind, in addition to high-quality iron ore and low steelworker wages. If coking coal prices remain high, fossil-free steel could attain competitiveness in favourable locations from 2030, further improving towards 2050. Large-scale implementation requires attention to the abundance of suitable iron ore and other resources such as land and water, technical challenges associated with direct reduction, and future supply chain configuration.

Combustion, Chemistry, and Carbon Neutrality

Combustion is a reactive oxidation process that releases energy bound in chemical compounds used as fuels─energy that is needed for power generation, transportation, heating, and industrial purposes. Because of greenhouse gas and local pollutant emissions associated with fossil fuels, combustion science and applications are challenged to abandon conventional pathways and to adapt toward the demand of future carbon neutrality. For the design of efficient, low-emission processes, understanding the details of the relevant chemical transformations is essential. Comprehensive knowledge gained from decades of fossil-fuel combustion research includes general principles for establishing and validating reaction mechanisms and process models, relying on both theory and experiments with a suite of analytic monitoring and sensing techniques. Such knowledge can be advantageously applied and extended to configure, analyze, and control new systems using different, nonfossil, potentially zero-carbon fuels. Understanding the impact of combustion and its links with chemistry needs some background. The introduction therefore combines information on exemplary cultural and technological achievements using combustion and on nature and effects of combustion emissions. Subsequently, the methodology of combustion chemistry research is described. A major part is devoted to fuels, followed by a discussion of selected combustion applications, illustrating the chemical information needed for the future.

The Materials Science behind Sustainable Metals and Alloys

Production of metals stands for 40% of all industrial greenhouse gas emissions, 10% of the global energy consumption, 3.2 billion tonnes of minerals mined, and several billion tonnes of by-products every year. Therefore, metals must become more sustainable. A circular economy model does not work, because market demand exceeds the available scrap currently by about two-thirds. Even under optimal conditions, at least one-third of the metals will also in the future come from primary production, creating huge emissions. Although the influence of metals on global warming has been discussed with respect to mitigation strategies and socio-economic factors, the fundamental materials science to make the metallurgical sector more sustainable has been less addressed. This may be attributed to the fact that the field of sustainable metals describes a global challenge, but not yet a homogeneous research field. However, the sheer magnitude of this challenge and its huge environmental effects, caused by more than 2 billion tonnes of metals produced every year, make its sustainability an essential research topic not only from a technological point of view but also from a basic materials research perspective. Therefore, this paper aims to identify and discuss the most pressing scientific bottleneck questions and key mechanisms, considering metal synthesis from primary (minerals), secondary (scrap), and tertiary (re-mined) sources as well as the energy-intensive downstream processing. Focus is placed on materials science aspects, particularly on those that help reduce CO₂ emissions, and less on process engineering or economy. The paper does not describe the devastating influence of metal-related greenhouse gas emissions on climate, but scientific approaches how to solve this problem, through research that can render metallurgy fossil-free. The content is considering only direct measures to metallurgical sustainability (production) and not indirect measures that materials leverage through their properties (strength, weight, longevity, functionality).

Contributions of key countries, enterprises, and refineries to greenhouse gas emissions in global oil refining, 2000-2021

The refining industry is the third-largest source of global greenhouse gas (GHG) emissions from stationary sources, so it is at the forefront of the energy transition and net zero pathways. The dynamics of contributors in this sector such as crucial countries, leading enterprises, and key emission processes are vital to identifying key GHG emitters and supporting targeted emission reduction, yet they are still poorly understood. Here, we established a global sub-refinery GHG emission dataset in a long time series based on life cycle method. Globally, cumulative GHG emissions from refineries reached approximately 34.1 gigatons (Gt) in the period 2000-2021 with an average annual increasing rate of 0.7%, dominated by the United States, EU27&UK, and China. In 2021, the top 20 countries with the largest GHG emissions of oil refining accounted for 83.9% of global emissions from refineries, compared with 79.5% in 2000. Moreover, over the past two decades, 53.9-57.0% of total GHG emissions came from the top 20 oil refining enterprises with the largest GHG emissions in 12 of these 20 countries. Retiring or installing mitigation technologies in the top 20% of refineries with the largest GHG emissions and refineries with GHG emissions of more than 0.1 Gt will reduce the level of GHG emissions by 38.0%-100.0% in these enterprises. Specifically, low-carbon technologies installed on furnaces and boilers as well as steam methane reforming will enable substantial GHG mitigation of more than 54.0% at the refining unit level. Therefore, our results suggest that policies targeting a relatively small number of super-emission contributors could significantly reduce GHG emissions from global oil refining.

Navigating within the Safe Operating Space with Carbon Capture On-Board

Despite the global pandemic that recently affected human and cargo transportation, the emissions of the maritime sector are projected to keep growing steadily. The International Maritime Organization focused on boosting the fleets' efficiency to improve their environmental performance, while more sustainable fuels are currently under investigation. Here, we assess the economic, technical, and environmental feasibility of an interim solution for low-carbon shipping using state-of-the-art CO₂ capture technology, namely, chemical absorption, on-board cargo ships. We compute the carbon footprint of this alternative and perform an absolute sustainability study based on seven planetary boundaries. Our results show that the capture on-board scenario can achieve 94% efficiency on the net CO₂ emissions at 85 $/tCO₂ while substantially reducing impacts on core planetary boundaries (relative to the business as usual) and outperforming a direct air capture scenario in global warming and all planetary boundaries, except for the nitrogen flow. Hence, capture on-board seems an appealing solution to decarbonize shipping in the short term while alternative carbon-free fuels and related infrastructure are developed and deployed.

Relocating Industrial Plants Delivers Win-Win Emission Reduction Benefits to Origin and Destination Regions

Relocating pollution-intensive factories is one of the most effective measures to meet mandatory environmental regulations in developed cities while simultaneously imposing environmental pressure on the receiving cities. Existing studies often assume that relocated plants produce the same or higher emissions when relocated. However, the current pollution mitigation policies enforce even higher emission standards in the destination after plant relocation. We employ a bottom-up pollution accounting approach to assess the impact of intraregional or interregional relocation of iron and steel plants in China's Beijing-Tianjin-Hebei (BTH) area on various air pollutants; specifically, seven policy scenarios are modeled, based on stringency, implementation scope, and production technologies. We find that relocation combined with emission standards enforcement and shifts from BOF (basic oxygen furnace) to EAF (electric arc furnace) production technology may significantly reduce emissions within and outside BTH areas by as much as 28.8% compared to business as usual. The observed reduction is mainly due to the requirement of meeting ultralow emission standards directly or indirectly after relocation. Both origin and destination cities benefit from the relocation, with limited emission spillovers (+9.1%) for destinations outside BTH and even a net reduction (9.4%) in Tangshan. We conclude that combining factory relocation with stricter emission standards and production technological innovation could circumvent the Pollution Haven Hypothesis and deliver win-win air pollution reduction benefits for both origins and destinations.

Influence of Specific Surface Area on the Strength of Iron Oxidized Pellets

Blaine specific surface area (SSA) is an essential physical property of iron concentrate and is availably improved by a high-pressure grinding roller (HPGR) to enhance the pelletability and the qualities of oxidized pellets. In this study, the four concentrates with various SSA were obtained by HPGR treatment to produce the oxidized pellets. The results show that the high degree of lattice deformation corresponds to high SSA which is beneficial for improving the quality of green, preheated, and fired pellets. The compressive strength increases from 600 to 1870 N·pellet−1 for preheated pellets and increases from 2530 to 4270 N·pellet−1 for fired pellets when SSA increased from 849 cm2/g to 1601 cm2/g, under the optimal condition of preheating at 1050 °C for 12 min and firing at 1250 °C for 15 min. The oxidation of magnetite is accelerated. Low porosity and microphotographs with integrated hematite joined crystallization support the strength enhancement by high SSA.

Assessing China's potential for reducing primary copper demand and associated environmental impacts in the context of energy transition and "Zero waste" policies

To conserve resources and enhance the environmental performance, China has launched the "Zero waste" concept, focused on reutilization of solid waste and recovery of materials, including copper. Although several studies have assessed the copper demand and recycling, there is a lack of understanding on how different waste management options would potentially reduce primary copper demand and associated environmental impacts in China in the context of energy transition. This study addresses this gap in view of a transition to low-carbon energy system and the optimization of copper waste management combining MFA and LCA approaches. Six types of waste streams (C&DW, ELV, WEEE, IEW, MSW, ICW) are investigated in relation to various "Zero waste" strategies including reduction, reuse (repair, remanufacturing or refurbishment), recycling and transition from informal to formal waste management. Under present Chinese policies, reuse and recycling of copper containing products will lead to a somewhat lower dependency on primary copper in 2100 (11187Gg), as well as lower total GHG emissions (64869 Gg CO2-eq.) and cumulative energy demand (1.18x10^12 MJ). Maximizing such "Zero waste" options may lead to a further reduction, resulting in 65% potential reduction of primary copper demand, around 55% potential reduction of total GHG emissions and total cumulative energy demand in 2100. Several policy actions are proposed to provide insights into future waste management in China as well as some of the challenges involved.

A Modular Tool to Support Data Management for LCA in Industry: Methodology, Application and Potentialities

Life Cycle Assessment (LCA) computes potential environmental impacts of a product or process. However, LCAs in the industrial sector are generally delivered through static yearly analyses which cannot capture any temporal dynamics of inventory data. Moreover, LCA must deal with differences across background models, Life Cycle Impact Assessment (LCIA) methods and specific rules of environmental labels, together with their developments over time and the difficulty of the non-expert organization staff to effectively interpret LCA results. A case study which discusses how to manage these barriers and their relevance is currently lacking. Here, we fill this gap by proposing a general methodology to develop a modular tool which integrates spreadsheets, LCA software, coding and visualization modules that can be independently modified while leaving the architecture unchanged. We test the tool within the ORI Martin secondary steelmaking plant, finding that it can manage (i) a high amount of primary foreground data to build a dynamic LCA; (ii) different background models, LCIA methods and environmental labels rules; (iii) interactive visualizations. Then, we outline the relevance of these capabilities since (i) temporal dynamics of foreground inventory data affect monthly LCA results, which may vary by ±14% around the yearly value; (ii) background datasets, LCIA methods and environmental label rules may alter LCA results by 20%; (iii) more than 105 LCA values can be clearly visualized through dynamically updated dashboards. Our work paves the way towards near-real-time LCA monitoring of single product batches, while contextualizing the company sustainability targets within global environmental trends.

Spatiotemporal carbon emissions across the spectrum of Chinese cities: Insights from socioeconomic characteristics and ecological capacity

In-depth investigation of the spatiotemporal driver patterns of city carbon emissions is vital toward establishing carbon neutrality, as such knowledge would aid policymakers in formulating differentiated emission reduction policies. Through developing a unique carbon emission dataset and applying a spatiotemporal logarithmic mean Divisia index decomposition approach, we explored the spatiotemporal drivers of CO₂ emission for diverse cities in China categorized by economic structure and population size during 2002-2018. The results highlighted GDP per capita and industrial structure as the most positive and negative drivers, respectively, with the former overweighing the latter before 2016. Furthermore, the between-group differences of cities categorized using population size were higher than differences within groups, implying evident heterogeneity of carbon emissions. Emission related to within-differences in net primary productivity (NPP) constitutes the largest contributing factor promoting carbon emission in megacities and highly industrialized cities, whereas NPP between-differences in agricultural carbon intensity are predominantly associated with inhibiting emissions in large and highly commercialized cities. We therefore suggest that policymakers should optimize the industrial structure in highly industrialized cities and develop carbon sequestration in cities with high vegetation coverage through fiscal transfer for achieving carbon neutrality.

Utilization of Hematite Particles for Economical Removal of o-xylene in a High-Temperature Gas-Solid Reactor

To establish a novel approach for VOCs resource utilization, coupled o-xylene oxidation and hematite reduction was investigated in this study in a high-temperature gas-solid reactor in the temperature range 300–700 °C. As the o-xylene-containing inert gas (N₂) stream traveled through the hematite particle bed, its reaction behavior was determined in programmed heating and constant temperature modes. Consequently, the effect of bed temperature, flow rate and o-xylene inlet concentration on both o-xylene removal performance and degree of hematite reduction was studied. The raw hematite and solid products were analyzed by TGA, XRF, XRD and SEM-EDS. The results showed that a temperature above 300 °C was required to completely eliminate o-xylene by hematite, and both o-xylene removal capacity and degree of hematite reduction at 5% breakthrough points enhanced on increasing the temperature and decreasing the flow rate. The increment in temperature from 300 °C to 700 °C led to a gradual reduction of Fe₂O₃ to Fe₃O₄, FeO and metallic iron. Thus, this study provides a novel, economic and promising technology for treating the VOC pollutants.

Hydrogen Recovery from Coke Oven Gas. Comparative Analysis of Technical Alternatives

The recovery of energy and valuable compounds from exhaust gases in the iron and steel industry deserves special attention due to the large power consumption and CO₂ emissions of the sector. In this sense, the hydrogen content of coke oven gas (COG) has positioned it as a promising source toward a hydrogen-based economy which could lead to economic and environmental benefits in the iron and steel industry. COG is presently used for heating purposes in coke batteries or furnaces, while in high production rate periods, surplus COG is burnt in flares and discharged into the atmosphere. Thus, the recovery of the valuable compounds of surplus COG, with a special focus on hydrogen, will increase the efficiency in the iron and steel industry compared to the conventional thermal use of COG. Different routes have been explored for the recovery of hydrogen from COG so far: i) separation/purification processes with pressure swing adsorption or membrane technology, ii) conversion routes that provide additional hydrogen from the chemical transformation of the methane contained in COG, and iii) direct use of COG as fuel for internal combustion engines or gas turbines with the aim of power generation. In this study, the strengths and bottlenecks of the main hydrogen recovery routes from COG are reviewed and discussed.

High-Resolution Environmentally Extended Input-Output Model to Assess the Greenhouse Gas Impact of Electronics in South Korea

South Korea is a global leader in electronics, but little is known about their climate change impact. Here, we estimate the direct and indirect greenhouse gas (GHG) emissions of Korean electronics by developing a new and high-resolution (∼380 sectors) environmentally extended input-output model, named KREEIO. We find that final demand for Korean electronics led to nearly 8% of national GHG emissions in 2017, mostly because of indirect emissions embodied in the electronics supply chain. Notably, the semiconductor and display sectors contributed 3.2% and 2.4% to national emissions, with capital investment accounting for 17% of the two sectors' total emissions or nearly 1% of national emissions. For other electronic products, scope 1, scope 2, and upstream scope 3 emissions on average accounted for 3%, 10%, and 87% of a sector's GHG intensity, respectively. Detailed contribution analysis suggests that reducing Korean electronics GHG emissions would benefit most from the transition to a low-carbon electricity grid, but mitigation efforts in many other sectors such as metals and chemicals are also important. Overall, our study underscores the significance of electronics GHG emissions in South Korea, especially those from semiconductors and displays, and the mitigation challenges these sectors face as demand continues to grow globally.

Drivers of CO2 Emissions: A Debt Perspective

CO2 emissions and debt accumulation are twin threats to sustainable development. To fill the gap that few studies can untangle the reasons behind CO2 emissions from the debt perspective, we illustrate debt can cause CO2 emissions through various channels. We then examined how debt-based drivers impact emission trajectories. We use the logarithmic mean Divisia index (LMDI) method to decompose the emission changes into five factors. We make decomposition analyses between different country groups to identify their respective characteristics. Further, to investigate the potential financial crisis impacts, we consider the full period 2001-2019 and two sub-periods (pre- and post-2008). The results show that the gross domestic product (GDP) is always the biggest contributor to emissions, whose effect on advanced economies saw a bigger decrease after 2008 than that on emerging economies. Debt-GDP is second only to GDP in contributing to emissions. It has a similar impact on emissions before and after 2008 for advanced economies, while it rockets after 2008 for emerging economies. Private debt financing of fossil fuels is the prominent inhibitor for both economies, especially for emerging economies. It has a stronger mitigation impact after 2008 than before for emerging economies, while has the opposite change for advanced economies. Debt structure and fossil CO2 intensity have relatively smaller effects on emissions. The crisis is an opportunity to promote low-carbon development. Since the COVID-19 pandemic is analogous to the 2008 crisis in terms of debt level and emission change, we provide recommendations for emission mitigation in the post-pandemic context.

Metallurgical Coke Production with Biomass Additives: Study of Biocoke Properties for Blast Furnace and Submerged Arc Furnace Purposes

Biocoke has the potential to reduce the fossil-based materials in metallurgical processes, along with mitigating anthropogenic CO₂- and greenhouse gas (GHG) emissions. Reducing those emissions is possible by using bio-based carbon, which is CO₂-neutral, as a partial replacement of fossil carbon. In this paper, the effect of adding 5, 10, 15, 30, and 45 wt.% biomass pellets on the reactivity, the physicomechanical, and electrical properties of biocoke was established to assess the possibility of using it as a fuel and reducing agent for a blast furnace (BF) or as a carbon source in a submerged arc furnace (SAF). Biocoke was obtained under laboratory conditions at final coking temperatures of 950 or 1100 °C. Research results indicate that for BF purposes, 5 wt.% biomass additives are the maximum as the reactivity increases and the strength after reaction with CO₂ decreases. On the other hand, biocoke’s physicomechanical and electrical properties, obtained at a carbonization temperature of 950 °C, can be considered a promising option for the SAF.

CO2 Reforming of CH4 Using Coke Oven Gas over Ni/MgO-Al2O3 Catalysts: Effect of the MgO:Al2O3 Ratio

Research is being actively conducted to improve the carbon deposition and sintering resistance of Ni-based catalysts. Among them, the Al2O3-supported Ni catalyst has been broadly studied for the dry reforming reaction due to its high CH4 activity at the beginning of the reaction. However, there is a problem of deactivation due to carbon deposition of Ni/Al2O3 catalyst and sintering of Ni, which is a catalytically active material. Supplementing MgO in Ni/Al2O3 catalyst can result in an improved MgAl2O4 spinel structure and basicity, which can be helpful for the activation of methane and carbon dioxide molecules. In order to confirm the optimal supports’ ratio in Ni/MgO-Al2O3 catalysts, the catalysts were prepared by supporting Ni after controlling the MgO:Al2O3 ratio stepwise, and the prepared catalysts were used for CO2 reforming of CH4 (CDR) using coke oven gas (COG). The catalytic reaction was conducted at 800 °C and at a high gas hourly space velocity (GHSV = 1,500,000 h−1) to screen the catalytic performance. The Ni/MgO-Al2O3 (MgO:Al2O3 = 3:7) catalyst showed the best catalytic performance between prepared catalysts. From this study, the ratio of MgO:Al2O3 was confirmed to affect not only the basicity of the catalyst but also the dispersion of the catalyst and the reducing property of the catalyst surface.

The Direct Reduction of Iron Ore with Hydrogen

The steel industry represents about 7% of the world’s anthropogenic CO2 emissions due to the high use of fossil fuels. The CO2-lean direct reduction of iron ore with hydrogen is considered to offer a high potential to reduce CO2 emissions, and this direct reduction of Fe2O3 powder is investigated in this research. The H2 reduction reaction kinetics and fluidization characteristics of fine and cohesive Fe2O3 particles were examined in a vibrated fluidized bed reactor. A smooth bubbling fluidization was achieved. An increase in external force due to vibration slightly increased the pressure drop. The minimum fluidization velocity was nearly independent of the operating temperature. The yield of the direct H2-driven reduction was examined and found to exceed 90%, with a maximum of 98% under the vibration of ~47 Hz with an amplitude of 0.6 mm, and operating temperatures close to 500 °C. Towards the future of direct steel ore reduction, cheap and “green” hydrogen sources need to be developed. H2 can be formed through various techniques with the catalytic decomposition of NH3 (and CH4), methanol and ethanol offering an important potential towards production cost, yield and environmental CO2 emission reductions.