Steel all over the world: Estimating in-use stocks of iron for 200 countries

Industrialization and urbanization in the developing world have boosted steel demand during the recent two decades. Reliable estimates on how much steel is required for high economic development are necessary to better understand the future challenges for employment, resource management, capacity planning, and climate change mitigation within the steel sector. During their use phase, steel-containing products provide service to people, and the size of the in-use stock of steel can serve as an indicator of the total service level. We apply dynamic material flow analysis to estimate in-use stocks of steel in about 200 countries and identify patterns of how stocks evolve over time. Three different models of the steel cycle are applied and a full uncertainty analysis is conducted to obtain reliable stock estimates for the period 1700–2008.Per capita in-use stocks in countries with a long industrial history, e.g., the U.S, the UK, or Germany, are between 11 and 16 tons, and stock accumulation is slowing down or has come to a halt. Stocks in countries that industrialized rather recently, such as South Korea or Portugal, are between 6 and 10 tons per capita and grow fast. In several countries, per capita in-use stocks of steel have saturated or are close to saturation. We identify the range of saturation to be 13 ± 2 tons for the total per capita stock, which includes 10 ± 2 tons for construction, 1.3 ± 0.5 tons for machinery, 1.5 ± 0.7 tons for transportation, and 0.6 ± 0.2 tons for appliances and containers. The time series for the stocks and the saturation levels can be used to estimate future steel production and scrap supply.     

In-depth analysis of aluminum flows in Austria as a basis to increase resource efficiency

Based on the method of material flow analysis (MFA), a static model of Austrian aluminum (Al) flows in 2010 was developed. Extensive data research on Al production, consumption, trade and waste management was conducted and resulted in a detailed model of national Al resources. Data uncertainty was considered in the model based on the application of a rigorous concept for data quality assessment. The model results indicated that the growth of the Austrian “in-use” Al stock amounts to 11 ± 3.1 kg yr⁻¹ cap⁻¹. The total “in-use” Al stock was determined using a bottom-up approach, which produced an estimate of 260 kg Al cap⁻¹. Approximately 7 ± 1 kg of Al yr⁻¹ cap⁻¹ of old scrap was generated in 2010, of which 20% was not recovered because of losses in waste management processes. Quantitatively, approximately 40% of the total scrap input to secondary Al production originated from net imports, highlighting the import dependency of Austrian Al refiners and remelters. Uncertainties in the calculation of recycling indicators for the Austrian Al system with high shares of foreign scrap trade were exemplarily illustrated for the old scrap ratio (OSR) in secondary Al production, resulting in a possible range of OSRs between 0 and 66%. Overall, the detailed MFA in this study provides a basis to identify resource potentials as well as resource losses in the national Al system, and it will serve as a starting point for a dynamic Al model to be developed in the future.     

Quantification and spatial characterization of in-use copper stocks in Shanghai

Shanghai is the largest industrial and commercial city of China, where in-use stocks of metals are likely to be significant. The in-use stocks of copper in this city are thus established by an extensive “bottom-up” study. Spatial distribution of copper stocks within Shanghai has further been characterized for better understanding of copper utilization pattern of this city. For the year 2012, the results are a total stock of 914.6 Gg Cu, and 38.4–64.1 kg Cu per capita. Nearly 94% of copper stocks distribute in subcategories of electric power transmission and distribution, water transmission and distribution, buildings, and household durable. Features of spatial distribution show that three central districts of Jing An, Hong Kou and Huang Pu have the spatial density of more than 1 Gg/km². And Chong Ming county and Jin Shan District have the lowest spatial density of about 0.01 Gg/km². It has been found that the copper stock density within Shanghai is largely determined by population density and economic development level.     

Environmental consequences of recycling aluminum old scrap in a global market

Nowadays, aluminum scrap is traded globally. This has increased the need to analyze the flows of aluminum scrap, as well as to determine the environmental consequences from aluminum recycling. The objective of this work is to determine the greenhouse gases (GHG) emissions of the old scrap collected and sorted for recycling, considering the market interactions. The study focused on Spain as a representative country for Europe. We integrate material flow analysis (MFA) with consequential life cycle assessment (CLCA) in order to determine the most likely destination for the old scrap and the most likely corresponding process affected. Based on this analysis, it is possible to project some scenarios and to quantify the GHG emissions (generated and avoided) associated with old scrap recycling within a global market. From the MFA results, we projected that the Spanish demand for aluminum products will be met mainly with an increase in primary aluminum imports, and the excess of old scrap not used in Spain will be exported in future years, mainly to Asia. Depending on the scenario and on the marginal source of primary aluminum considered, the GHG emission estimates varied between −18,140 kg of CO₂ eq. t⁻¹ and −8427 of CO₂ eq. t⁻¹ of old scrap collected. More GHG emissions are avoided with an increase in export flows, but the export of old scrap should be considered as the loss of a key resource, and in the long term, it will also affect the semifinished products industry. Mapping the flows of raw materials and waste, as well as quantifying the GHG impacts derived from recycling, has become an essential prerequisite to consistent development from a linear toward a circular economy (CE).     

The contemporary European silver cycle

This paper examines the 1-year anthropogenic stocks and flows of silver as it progresses from extraction to final disposal on the European continent. The primary flows of silver include production, fabrication and manufacturing, use, and waste management. A substance flow analysis (SFA) was used to trace the flows and inventory data, and mass balance equations were used to determine the quantity of flows. The results reveal that Europe has a low level of silver mine production (1580 Mg Ag/year) and instead relies on silver imports and the recycling of scrap in production and fabrication. In the year 1997, Europe imported 1160 Mg Ag of ore concentrate and 2010 Mg Ag of refined silver, and recycled 2750 Mg Ag of new and old scrap. There is a net addition of 3320 Mg Ag/year into silver reservoirs at the use stage. This is the result of a greater amount of silver entering the system from manufacturing than is leaving the system into waste management. The waste flow with the highest content of silver is municipal solid waste, which contains 1180 Mg Ag/year. In total, 62% of all discarded silver is recycled and 38% is sent to landfills. The results of this study and other element and material flow analyses can help guide resource managers, environmental policy makers, and environmental scientists in their efforts to increase material recovery and recycling, address resource sustainability, and ameliorate environmental problems.     

Estimating rainforest biomass stocks and carbon loss from deforestation and degradation in Papua New Guinea 1972–2002: Best estimates,uncertainties and research needs

Reduction of carbon emissions from tropical deforestation and forest degradation is being considered a cost-effective way of mitigating the impacts of global warming. If such reductions are to be implemented, accurate and repeatable measurements of forest cover change and biomass will be required. In Papua New Guinea (PNG), which has one of the world's largest remaining areas of tropical forest, we used the best available data to estimate rainforest carbon stocks, and emissions from deforestation and degradation. We collated all available PNG field measurements which could be used to estimate carbon stocks in logged and unlogged forest. We extrapolated these plot-level estimates across the forested landscape using high-resolution forest mapping. We found the best estimate of forest carbon stocks contained in logged and unlogged forest in 2002 to be 4770 Mt (±13%). Our best estimate of gross forest carbon released through deforestation and degradation between 1972 and 2002 was 1178 Mt (±18%). By applying a long-term forest change model, we estimated that the carbon loss resulting from deforestation and degradation in 2001 was 53 Mt (±18%), rising from 24 Mt (±15%) in 1972. Forty-one percent of 2001 emissions resulted from logging, rising from 21% in 1972. Reducing emissions from logging is therefore a priority for PNG. The large uncertainty in our estimates of carbon stocks and fluxes is primarily due to the dearth of field measurements in both logged and unlogged forest, and the lack of PNG logging damage studies. Research priorities for PNG to increase the accuracy of forest carbon stock assessments are the collection of field measurements in unlogged forest and more spatially explicit logging damage studies.     

Estimation of in-use steel stock for civil engineering and building using nighttime light images

To establish a sustainable society, it is necessary to understand the flows and stocks of materials. However, traditional material flow analysis requires large quantities of data relating to the consumption and trade of materials in the past and the lifetime distributions of end use. To overcome the problem that such data may not be available, we have proposed using nighttime light images to estimate the in-use stocks of materials in countries for which the data are unavailable. In the previous study, in-use steel stock for civil engineering and building in 2006 was estimated using nighttime light images. However, several aspects of the methodology must be improved, and time-series analyses using nighttime light images have not yet been performed. Therefore, in this study, we improved the estimation of in-use steel stock by using new geological information (i.e., LandScan population distribution data) and correcting the pixel area. We prepared radiance-calibrated nighttime light data for 2006 and 2010 and conducted time-series analyses of the in-use steel stock using the nighttime light data. The in-use steel stock for civil engineering and building in 2010 was found to amount to approximately 11.3 Gt, which was approximately 21% higher than that in 2006.     

Substance flow analysis of cadmium in Korea

Substance flow analysis (SFA) of cadmium in Korea was carried out to analyze and predict cadmium flows, stocks, and future flows using both static and dynamic models. Cadmium is widely used in industry due to its strong corrosion and chemical resistance at high temperature, excellent electrical conduction, and low melting-point. Cadmium is produced as a by-product from the production processes for zinc and lead ingots. It is used for Ni–Cd batteries, polyvinylchloride (PVC) stabilizers, alloy products, pigments, and others.This examines the current cadmium flows and stocks using static SFA, and aims in predicting the future cadmium flows and stocks in Korea using dynamic SFA. From the static model, 2820 tonnes of cadmium ingots were produced, 0.04 tonnes imported and 2740 tons exported in Korea in 2009. In addition, 81 tonnes of cadmium were used in the manufacture of cadmium products: 80 tonnes for cadmium alloy products and 1 tonne for others. Finally, 175 tonnes of cadmium were imported into Korea for Ni–Cd batteries, 140 tonnes for PVC stabilizers, and 55 tonnes for pigments. Cadmium was used in various industries such as construction (221 tonnes), electrics and electronics (130 tonnes – including cadmium in imported products), transportation (30 tonnes) and others (30 tonnes). In 2009, 430 tonnes of industrial cadmium were discharged, with 10 tonnes being recycled and 420 tonnes discarded.From the dynamic model, cadmium stocks in Korea were estimated to be about 5120 tonnes in 2009. The industrial consumption in 2030 will be reduced to only 110 tonnes, only 27% of the current consumption of 410 tonnes in 2009, due to DIRECTIVE 2002/95/EC OF THE EUROPEAN PARLIAMENT of 27 January 2003 on the restriction of the use of certain hazardous substances in electrical and electronic equipment (RoHS). One possible solution to the Cd oversupply problem is use in cadmium telluride photovoltaic (CdTe PV) systems which have low life cycle Cd emissions (0.02 g Cd/GWh) and high end-of-life semiconductor recycling yields (95%).     

Global anthropogenic selenium cycles for 1940–2010

Selenium plays an important role in emerging thin film solar energy technologies. As solar energy is expected to have a larger share in the world's future energy portfolio, the long-term availability of selenium becomes a potential concern, yet no global cycles have ever been generated. In this work, the global cycles, stocks, and flows of selenium are characterized for the entire time period 1940–2010 by using principles of material flow analysis (MFA). The cycles present information on the production, fabrication and manufacturing, use, and resource management stages during that period. The results of the analysis show that during 1940–2010 approximately 90 Gg of refined selenium was produced and entered into fabrication and manufacturing worldwide. 60 Gg of this amount (two-thirds!) was dissipated into the environment through end-uses such as chemicals, pigments, glass manufacturing, metallurgical additives, and fertilizer and feed additives. The in-use stock of selenium is estimated at 2.7 Gg as of 2010. Because of data limitations such as proprietary and withheld information, these figures represent informed estimates rather than exact values. Selenium can be recovered from end-of-life electrical and electronic equipment, while for other end-uses recycling is difficult or impossible. One of the ways to buttress supplies of selenium for future technologies would be to deploy recycling schemes for photovoltaics as well as other electronics applications.     

The Austrian P budget as a basis for resource optimization

Phosphorus (P) is a finite and non-substitutable resource that is essential to sustaining high levels of agricultural productivity but is also responsible for environmental problems, e.g., eutrophication. Based on the methodology of Material Flow Analysis, this study attempts to quantify all relevant flows and stocks of phosphorus (P) in Austria, with a special focus on waste and wastewater management. The system is modeled with the software STAN, which considers data uncertainty and applies data reconciliation and error propagation. The main novelty of this work lies in the high level of detail at which flows and stocks have been quantified to achieve a deeper understanding of the system and to provide a sound basis for the evaluation of various management options. The budget confirms on the one hand the dependence of mineral P fertilizer application (2 kg cap⁻¹ yr⁻¹), but it highlights on the other hand considerable unexploited potential for improvement. For example, municipal sewage sludge (0.75 kg cap⁻¹ yr⁻¹) and meat and bone meal (0.65 kg cap⁻¹ yr⁻¹) could potentially substitute 70% of the total applied mineral P fertilizers. However, recycling rates are low for several P flows (e.g., 27% of municipal sewage sludge; 3% of meat and bone meal). Therefore, Austria is building up a remarkable P stock (2.1 kg P cap⁻¹ yr⁻¹), mainly due to accumulation in landfills (1.1 kg P cap⁻¹ yr⁻¹) and agricultural soils (0.48 kg P cap⁻¹ yr⁻¹).     

Global anthropogenic tellurium cycles for 1940–2010

Tellurium is increasingly used in solar photovoltaics in the form of cadmium–telluride (CdTe) thin films. There are concerns regarding whether tellurium availability could be a constraint on large-scale deployment of CdTe photovoltaics. The present work brings a new perspective to the discussion of tellurium availability by providing the first extant global tellurium cycles constructed with material flow analysis principles. The tellurium cycles, for 1940–2010, present information on the production, fabrication and manufacturing, use, and resource management stages during this period. The results of the analysis show that during 1940–2010 approximately 11 Gg of refined tellurium was produced. This represents about 4.5% of the tellurium that was extracted from the ground during copper mining. Almost 80% of the refined tellurium, 8.5 Gg, was dissipated into end-uses such as metallurgical additives to iron, steel, and nonferrous metals, and thereby lost to potential reuse. As of 2010, the in-use tellurium stock is estimated at 1.1 Gg, which mainly accumulated after 1990s with the increasing tellurium use in electronics, specifically photovoltaic and thermoelectric devices. Because tellurium is a byproduct of copper ores, its supply can be enhanced by more attention to recovery during processing of the copper parent. Tellurium can also, in principle, be recovered from end-of-life electronics; the increasing in-use stock indicates the potential for significant end-of-life recycling in the coming decades.     

Pathways towards large-scale implementation of CO2 capture and storage: A case study for the Netherlands

We sketch four possible pathways how carbon dioxide capture and storage (CCS) (r)evolution may occur in the Netherlands, after which the implications in terms of CO₂ stored and avoided, costs and infrastructural requirements are quantified. CCS may play a significant role in decarbonising the Dutch energy and industrial sector, which currently emits nearly 100 Mt CO₂/year. We found that 15 Mt CO₂ could be avoided annually by 2020, provided some of the larger gas fields that become available the coming decade could be used for CO₂ storage. Halfway this century, the mitigation potential of CCS in the power sector, industry and transport fuel production is estimated at maximally 80–110 Mt CO₂/year, of which 60–80 Mt CO₂/year may be avoided at costs between 15 and 40 €/t CO₂, including transport and storage. Avoiding 30–60 Mt CO₂/year by means of CCS is considered realistic given the storage potential represented by Dutch gas fields, although it requires planning to assure that domestic storage capacity could be used for CO₂ storage. In an aggressive climate policy, avoiding another 50 Mt CO₂/year may be possible provided that nearly all capture opportunities that occur are taken. Storing such large amounts of CO₂ would only be possible if the Groningen gas field or large reservoirs in the British or Norwegian part of the North Sea will become available.     

Approaches for analyzing local carbon mitigation strategies: Tompkins County,New York,USA

A carbon budget was calculated for Tompkins County, NY, a semi-rural upstate county with a population density of 78 pp/km². The costs and potential for several carbon mitigation options were analyzed in four categories: terrestrial C sequestration, local power generation, transportation, and energy end-use efficiency. This study outlines a methodology for conducting this type of local-scale analysis, including sources and calculations adaptable to different localities. Effective carbon mitigation strategies for this county based on costs/Mg C and maximum potential include reforestation of abandoned agricultural lands, biomass production for residential heating and co-firing in coal power plants, changes in personal behavior related to transportation (e.g., public transportation), installation of residential energy efficient products such as programmable thermostats or compact fluorescent light bulbs, and development of local wind power. The total county emissions are about 340 Gg C/year, with biomass sequestration rates of 121 Gg C/year. The potential for mitigation, assuming full market penetration, amounts to about 234 Gg C/year (69%), with 100 Gg C/year (29%) at no net cost to the consumer. The development of local-scale C mitigation plans based on this sort of model of analysis is feasible and would be useful for guiding investments in climate change prevention.     

Watershed-scale assessment of arsenic and metal contamination in the surface soils surrounding Miyun Reservoir,Beijing, China

Concentrations of As and selected metals were determined in surface soils of the Miyun Reservoir watershed of Beijing, China. The degree to which concentrations of As and metals exceeded the corresponding background concentration of soils was: Cr > Cu > Zn > As > Ni with no apparent anthropogenic contamination with Cd and Pb. Based on the results of a combination of multivariate statistics and geostatistical analysis, greater concentrations of Cr and Ni in soils were determined to be primarily from iron ore mining near where the Chaohe River enters the northeast portion of the reservoir. Agricultural activities were responsible for the observed elevated concentrations of Cu and Zn in soils. Relatively great concentrations of As were found in soils near the upstream regions of the Baihe River in Chicheng County where small gold mining activities have taken place. The greatest potential for adverse effects of Cr and Cu occurred along the eastern shore of Miyun Reservoir.     

Geological storage of CO2 in saline aquifers—A review of the experience from existing storage operations

The experience from CO₂ injection at pilot projects (Frio, Ketzin, Nagaoka, US Regional Partnerships) and existing commercial operations (Sleipner, Snøhvit, In Salah, acid-gas injection) demonstrates that CO₂ geological storage in saline aquifers is technologically feasible. Monitoring and verification technologies have been tested and demonstrated to detect and track the CO₂ plume in different subsurface geological environments. By the end of 2008, approximately 20 Mt of CO₂ had been successfully injected into saline aquifers by existing operations. Currently, the highest injection rate and total storage volume for a single storage operation are approximately 1 Mt CO₂/year and 25 Mt, respectively. If carbon capture and storage (CCS) is to be an effective option for decreasing greenhouse gas emissions, commercial-scale storage operations will require orders of magnitude larger storage capacity than accessed by the existing sites. As a result, new demonstration projects will need to develop and test injection strategies that consider multiple injection wells and the optimisation of the usage of storage space. To accelerate large-scale CCS deployment, demonstration projects should be selected that can be readily employed for commercial use; i.e. projects that fully integrate the capture, transport and storage processes at an industrial emissions source.     

Butyltin occurrence and risk assessment in the sediments of the Iberian Peninsula

The occurrence of butyltin (BT) compounds in more than 50 recent sediment samples of the Iberian Peninsula, collected in the harbours of the western Mediterranean Sea (Spain) and the North Atlantic Ocean (Portugal), including domestic and industrial sewage disposal sites, has been assessed. The highest levels of tributyltin (TBT) (7673 μg kg^?1 dry wt.) were detected in commercial harbours associated with inputs from large vessels. However, relatively high TBT values (about 2150 μg kg^?1 dry wt.) were also detected in fishing and recreational boating areas. Spanish marinas and harbours are more polluted in terms of TBT (5–7673 μg kg^?1 dry wt.) compared to those in Portugal (4–12 μg kg^?1 dry wt.). Generally, the Mediterranean sediments show a BT distribution characterized by the predominance of TBT over the degradation products dibutyl (DBT) and monobutyltin (MBT), indicating the presence of recent inputs, in contrast to the Portuguese coastal distribution. Calculation of butyltin degradation indexes (BDI) confirmed a different trend, depending on the area. Furthermore, a comparative study of the occurrence of BT in different sewage sludge disposal sites shows that domestic primary sewage sludge effluents can contribute to coastal BT pollution, but to a lesser extent when compared with harbours. Historical trends (1995–2003) for Barcelona harbour reveal that BT regulations on the use of TBT-based antifouling paints have not been fully effective. Finally, a comparison against the existing sediment quality guidelines (SQGs) indicated that acute toxic effects could only be expected for TBT in some Mediterranean harbours; conversely, in every North Atlantic Ocean station, a lesser environmental threat for the harbour benthic community is expected.     

Transfer characteristics of cobalt from soil to crops in the suburban areas of Fujian Province,southeast China

The bioavailability of cobalt and its transfer from soil to vegetables and rice were investigated. Among 312 soils collected from vegetable and paddy fields in the suburban areas of some major cities of Fujian Province, southeast China, total soil Co ranged from 3.5 to 21.7 mg kg^?1, indicating a slight accumulation compared with the background value of the province. DTPA extracted 0.1–8.5% of soil total Co. Total and DTPA-extractable Co correlated with soil pH, CEC, free Fe, total Mn, clay and silt content more significantly in paddy soils than in the soils from vegetable fields. The average Co concentrations in the edible parts of vegetables and rice were 15.4 μg kg^?1 and 15.5 μg kg^?1, respectively. The transfer factor (the ratio of plant Co to soil DTPA-extractable Co, TF_DTPA) ranged from 0.003 to 0.126 with a median of 0.049. The TF_DTPA decreased in the order of leafy vegetables > fruit vegetables > root vegetables > rice. The TF_DTPA of all crops decreased with increasing DTPA-extractable Co. Increase in pH, CEC, organic matter, clay, silt, free iron and total Mn limited the soil-to-plant transfer of Co to varying degrees. The transfer of Co from the soils to the edible parts of the crops was lower than that of Zn, Cu and Cd, but higher than that of Pb in the same areas. The concentrations of Co in rice and vegetables in the study areas were considered to be safe for the local residents because of the slight anthropogenic input and the low transfer potential to the edible parts of Co from the soils.     

Energy balances,greenhouse gas emissions and economics of biochar production from palm oil empty fruit bunches

This paper presents results from a gate-to-gate analysis of the energy balance, greenhouse gas (GHG) emissions and economic efficiency of biochar production from palm oil empty fruit bunches (EFB). The analysis is based on data obtained from EFB combustion in a slow pyrolysis plant in Selangor, Malaysia. The outputs of the slow pyrolysis plant are biochar, syngas, bio-oil and water vapor. The net energy yield of the biochar produced in the Selangor plant is 11.47 MJ kg⁻¹ EFB. The energy content of the biochar produced is higher than the energy required for producing the biochar, i.e. the energy balance of biochar production is positive. The combustion of EFB using diesel fuel has the largest energy demand of 2.31 MJ kg⁻¹ EFB in the pyrolysis process. Comparatively smaller amounts of energy are required as electricity (0.39 MJ kg⁻¹ EFB) and for transportation of biochar to the warehouse and the field (0.13 MJ kg⁻¹ EFB). The net greenhouse gas emissions of the studied biochar production account for 0.046 kg CO₂-equiv. kg⁻¹ EFB yr⁻¹ without considering fertilizer substitution effects and carbon accumulation from biochar in the soil. The studied biochar production is profitable where biochar can be sold for at least 533 US-$ t⁻¹. Potential measures for improvement are discussed, including higher productivity of biochar production, reduced energy consumption and efficient use of the byproducts from the slow pyrolysis.     

Dynamic material flow analysis of steel resources in Korea

Material flow analysis (MFA) is an evaluation technique that systematically identifies the flows and stocks of materials within predefined spatial and temporal boundaries. In this paper, the steel resources in Korea are investigated using dynamic MFA. Iron ore and steel scrap are added as raw material components during the production processes of steel, which is then used in a variety of product groups such as construction products, transportation equipment, machinery/metal products, electrical/electronic devices, and other products through fabrication and manufacturing processes. When such product groups are discarded, they are either recycled or landfilled. With consideration for the lifetimes of various product groups in conjunction with steel resource flows in Korea, dynamic MFA is conducted on the flows of steel stock change and annual scrap generation. By 2020, these two flows are expected to increase by as much as 40% and 30%, respectively, compared to 2008, with transportation equipment, in particular, envisaged to experience high growth. At the current recycling rate, however, it will be hard to meet future scrap demand. According to the scenario analysis, 100% of this future scrap demand can be supplied domestically if the recycling rate is increased to over 70% for all product groups, except construction products and transportation equipment, which already have high recycling rates. By 2020, the reduction in scrap importation costs is projected to offer a financial gain of 2.3 billion dollars.