Consumption-based accounting of steel alloying elements and greenhouse gas emissions associated with the metal use: The case of Japan

Ohno, Hajime et al. Article Consumption-based accounting of steel alloying elements and greenhouse gas emissions associated with the metal use: The case of Japan Journal of Economic Structures Provided in Cooperation with: Pan-Pacific Association of Input-Output Studies (PAPAIOS) Suggested Citation: Ohno, Hajime et al. (2016) : Consumption-based accounting of steel alloying elements and greenhouse gas emissions associated with the metal use: The case of Japan, Journal of Economic Structures, ISSN 2193-2409, Springer, Heidelberg, Vol. 5, Iss. 28, pp. 1-17, https://doi.org/10.1186/s40008-016-0060-9 This Version is available at: https://hdl.handle.net/10419/194937 Standard-Nutzungsbedingungen: Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. 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If the documents have been made available under an Open Content Licence (especially Creative Commons Licences), you may exercise further usage rights as specified in the indicated licence. https://creativecommons.org/licenses/by/4.0/ Consumption‑based accounting ofsteel alloying elements andgreenhouse gas emissions associated withthe metal use: the case ofJapan Hajime Ohno1*, Kazuyo Matsubae2, Kenichi Nakajima3, Keisuke Nansai3, Yasuhiro Fukushima1 and Tetsuya Nagasaka1 Abstract Metal extraction and smelting cause considerable impacts on the environment. Consumption-based impact accounting highlights the responsibility of metal-consuming industries for the impacts and may drive a system-wide improvement in the structure of related supply chains. To drive the improvements, policies at national level coordinated for respective product types across the nations is needed. However, nationwide responsibility for specific use of metals is difficult to identify because metals are manufactured into composite products (e.g., vehicles) in a country that is in many cases, different from the country where mining is practiced. The final product environmental footprints would not reveal the location where the various impacts are caused. This study presents a method to support the policy coordination by identifying the magnitude of the responsibility of metal-consuming countries for environmental impacts occurred in mining countries so that the countries sharing large responsibilities can find partner countries to jointly work on reduction in environmental impacts effectively. An input–output-based material flow analysis model is used to track the flows of metals included in products made in Japan throughout the international supply chain. In 2005, Japanese industries collected steel alloying elements (manganese, chromium, nickel, molybdenum) embodying 3200 kt-CO2eq and distributed them as both intermediate and final products. For steel mill products, Asian countries were the main destination, while alloying elements contained in other products were relatively evenly exported to Asia, Europe, and North America. By consuming products made in Japan, South Korea, China, the USA, and Taiwan shared approximately 10% each in terms of share of responsibility for greenhouse gas emission embodied in alloying element collected by Japan. Japan shared 40% of the responsibility with domestic consumption of own products. These findings suggest that Japan, a collector and distributor of steel alloying elements, must work on its own resource use reduction policies coordinating with these countries to globally develop sustainable resource use system. Keywords: Material flow analysis, Input–output analysis, International trade, Steel alloying element, Greenhouse gas emissions, Consumption base Open Access © The Author(s) 2016. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. RESEARCH Ohno et al. Economic Structures (2016) 5:28 DOI 10.1186/s40008‑016‑0060‑9 *Correspondence: [email protected]ohoku.ac.jp 1 Graduate School of Engineering, Tohoku University, Miyagi 980-8579, Japan Full list of author information is available at the end of the article Page 2 of 17 Ohno et al. Economic Structures (2016) 5:28 1 Background Metals are indispensable in our society. To obtain sufficient metals for economic development, huge amounts of ores and industrial minerals are extracted globally (United Nations Environment Programme (UNEP) 2011); on the other hand, metal mining and smelting cause negative environmental impacts (Nuss and Eckelman 2014). Because the impacts of these processes directly affect the environment of mining and material processing countries, metal-consuming countries have indirect responsibilities for the impacts occurred in metal-producing countries according to own consumptions (Peters 2008; Peters and Hertwich 2008). Once metals have been mined, smelted, and refined, they are consumed in the mined country and/or exported. Countries that import metals use them to produce various value-added products, consume the products themselves, and/or export them. However, this supply chain is unevenly distributed among countries. Mined metals tend to be collected by industrialized countries and then redistributed in the form of finished products through the international supply chain (Wiebe etal. 2012; Nansai etal. 2014; Wiedmann etal. 2015). As the UNEP International Resource Panel points out, decoupling resource use and negative environmental impacts from economic growth is important for the development of a sustainable society (UNEP 2011). Improving resource efficiency and/or productivity is one of the key concepts for decoupling, although countries have been tackling such improvements in their own ways, which may not be the best approach to reaching the overarching objective. Consumption-based impact accounting, which considers the responsibility for environmental impacts in upstream supply chains, is different in that it places the responsibility on those countries that benefit from the products (Peters 2008; Peters and Hertwich 2008; Shigetomi etal. 2015, 2016). For example, if demand in country A for the products of country B induces huge resource use in country B, country A would be obliged to contribute to the activities in country B for improving resource efficiency and/or productivity. In this regard, the need for decoupling should be tackled through international cooperation. In this paper, we demonstrate how a country can identify the magnitude of the responsibility sharing with other countries and find out the target countries to jointly work on impact reduction. Moreover, the flow of metals accompanying with international trade is revealed and the environmental impacts on the countries in the supply chain are organized to discuss the nature of the international coordination. A case study is then demonstrated by using the case of Japan and its use of alloying metal in the steel industry. As an industrialized country, Japan contributes highly to the international flow of metals; Japan, who has the second largest steel production and third largest automobile production in the world (International Organization of Motor Vehicle Manufactures (OICA) 2015; World Steel Association 2015) without having any resource deposits, has considerable responsibilities for metal mining countries in order to drive its large metal fabricating industries. At the same time, Japan exports more than 40% of the produced steel mill products (World Steel Association 2015) and around 50% of the produced automobiles (Japan Automobile Manufacture Association (JAMA) 2015) every year. Hence, Japan is passing on the responsibility for metal use to consuming countries as well as exporting metal-containing products (Kondo etal. 1998; Peters 2008). In terms Page 3 of 17 Ohno et al. Economic Structures (2016) 5:28 of alloying elements, Japan consumes about 10% of the world’s steel alloying elements (Japan Oil Gas and Metals National Corporation (JOGMEC) 2008). Among steel alloying elements, we focus on manganese, chromium, nickel, and molybdenum whose consumption in steel industries is relatively great compared with those in other industries in Japan (JOGMEC 2007). Steel alloying elements add various properties to steel such as corrosion resistance, heat resistance, and toughness (Nakajima etal. 2013). Steel mill products containing alloying elements (so-called alloy steel) are utilized widely in industries requiring high-performance materials, such as the automobile and machinery industries. The content of alloying elements in steel mill and other fabricated products is estimated by using the waste input–output material flow analysis (WIO-MFA) model (Nakamura etal. 2007; Nakajima etal. 2013; Ohno etal. 2014). By using the WIO-MFA model to identify the content of alloying elements, metal compositions in highly fabricated products are derived based on IO analysis, whereas the representative compositions must be carefully chosen in process-based bottom-up MFAs. Nansai et al. (2009, 2012) evaluated the carbon footprints of 230 countries and regions induced by Japanese economic activities by using the global link IO model. Their approach of connecting Japanese IO tables with international trade information is well suited to the use of WIO-MFA. Nakajima etal. (2011a) and Nansai etal. (2014) calculated the flows of metals accompanying with Japan’s international trade by combining the WIO-MFA and global link IO models. Furthermore, Nakajima etal. (2014) addressed the global supply chain of nickel and examined its influence on the environment of mining sites. Following this previous research, we examine the following three factors: 1. The flow of steel alloying elements collected by Japan by distinguishing domestic use from exports; 2. The international flow of steel alloying elements accompanying with the exports of Japanese products; and 3. The responsibility for environmental impacts in mining and material processing countries, using greenhouse gas (GHG) emissions as a proxy for the environmental impact in mining and material processing countries. The study and inventory data of lifecycle assessment for metal production (Ecoinvent 2010; Eckelman 2010; Nuss and Eckelman 2014) are referred for accounting GHG emission in mining and material processing countries. As shown in Fig.1, we untangle the links between mining countries and both Japan and countries who import products made in Japan according to consumption-based thinking in order to clarify the attribution of the responsibility for environmental impacts in mining and material processing countries. We then discuss who should be involved in the activities of a country to improve resource efficiency. For the accounting method of the responsibility, Lenzen etal. (2007) proposed “shared responsibility” between producer and consumer. In this accounting, the shortcomings of both full producer and full consumer responsibility accountings such as double counting and lack of full life cycle description can be filled up by allocating responsibilities among the supply Page 4 of 17 Ohno et al. Economic Structures (2016) 5:28 chain. Although the present study also argues about producers (i.e., mining and metal processing countries) and consumers (i.e., metal-consuming countries) in the supply chain as the same as Lenzen etal. (2007), we only take consumer responsibility for the impact directly occurred in producer countries into account. In other words, we distinguish environmental impacts on metal mining and producing countries from total environmental impacts including on metal processing countries and allocate the responsibility for the impacts on mining and producing countries to metal-consuming countries according to the share of metal-including products made in Japan. It is because impacts of mining and primary metal production tend to directly and quickly affect the surrounding environment and biodiversity rather than climate change derived by GHG emission (Nakajima etal. 2014). Ironically, however, we quantify the impact in terms of GHG emission as a proxy for the environmental impact in metal mining and producing countries instead of on the typical direct impacts such as land use changes and/or biodiversity threats which we indeed want to evaluate due to the lack of inventory data on them. The difficulty is that metals are mined in different methods such as open pit and pit mining, different forms such as oxide ore or sulfide ore, and smelted with different processes such as hydro- and/or pyro-metallurgy. This variety makes it difficult to create Fig. 1 Schematic image of the attribution and proportion of the responsibility for environmental impacts in mining and processing countries Page 5 of 17 Ohno et al. Economic Structures (2016) 5:28 homogeneous inventory data about direct impacts for each metal. For the same reason, producers of metal resources providing metals for Japan are not particularly focused on. 2 Methodology anddata 2.1 WIO‑MFA WIO-MFA provides the composition of materials in commodities by counting the direct and indirect flows of materials in an economy based on IO analysis. The composition of materials in commodities CMP is derived as follows: Here, ˜ A represents the “filtered” input coefficient matrix and the subscripts M and P, respectively, denote materials and products, indicating the category of inputs and outputs. “Filtered” means that the inputs do not form mass of a product (i.e., services, electricity, and process losses of materials) that are removed from the general input coefficient matrix by multiplying filter matrices (Nakamura etal. 2007). ˜ AMP stands for the matrix of the input coefficients of materials to the production of products, and ˜ APP is for the input of products to the production of products. The unit of elements in ˜ AMP is the physical unit per monetary unit (e.g., ton/million yen for Japan). Because the elements in ˜ APP have no unit (i.e., monetary unit/monetary unit), the unit of elements in CMP becomes the physical unit per monetary unit as well as ˜ AMP . This means that the (i, j)-element of CMP represents the mass of material i directly and indirectly introduced in one monetary unit of production of product j. In the case of Japanese IO, for instance, when material i and product j are pig iron and passenger cars, respectively, the meaning of the (i, j)-element of CMP is the mass of pig iron contained in one million yen of passenger cars. For steel mill products, their inputs and productions are expressed in physical units instead of monetary units for other products. Thus, the elements in CMP represent the mass of materials directly and indirectly contained in one physical unit of products. By introducing a vector qe representing contents of alloying element e in each material, CMP can be converted to Ce MP representing contents of alloying element e in products. Here, qT e represents transpose of qe . For further details on the model, see previous studies (Nakamura and Nakajima 2005; Nakamura etal. 2007). 2.2 MFA ofalloying elements indomestic final demand andexport Let T be the matrix whose (i, j)-element represents the amount of goods i exported from Japan to country or region j and DExp e be the matrix of the mass of accompanying alloying element e with the export in goods i with country or region j. By applying Ce MP obtained which represents the vector of contents of alloying element e in products, D Exp e=  dExp eij  can be estimated as follows: (1) C MP =˜ AMP  I−˜ APP −1 (2) Ce MP =q T e C MP (3) DExp e =diag  C e MPT Page 6 of 17 Ohno et al. Economic Structures (2016) 5:28 Similarly, the mass of alloying elements contained in final products domestically consumed in Japan is obtained as follows: Here, D JP e=  dJP ei  represents the vector of an element contents in domestically consumed goods i and fJP is the vector of the domestic final demands. Then, the share of the consumption of alloying elements is formulated as follows: Here, SJP e and Sj e represent the share of Japan and country j for the consumption of alloying element e contained in Japanese products and ng and nc are the number of goods (528) and countries except Japan (230), respectively. 2.3 Share ofthe responsibility The embodied GHG emission in the imported alloying element sources for Japan is calculated by multiplying each inventory listed in the next section by imported masses of alloying element sources. The total amounts of embodied GHG emission for each alloying element are the sum of the embodied GHG emissions of corresponding sources imported by Japan. Let εe be the scalar of the total amount of GHG emission embodied in an element e introduced to Japan. Applying the share of the consumption of alloying elements obtained by Eqs.(5) and (6) to εe , the responsibility for GHG emission: Re is allocated to Japan and other countries importing Japanese products as follows: Here, RJP e and Rj e represent the responsibility for GHG emission embodied in an alloying element e attributed to Japan and country j, respectively. Consequently, the size of Re is 231 ×1 . Then, by summing up the responsibilities for four alloying elements, total responsibility for country i: R=(Ri) is obtained as follows: The set E is for alloying elements including manganese, chromium, nickel, and molybdenum. Because the GHG emissions embodied in each alloying element are varied, the share of responsibility is different from the total share of the consumption of alloying elements. The share of responsibility is then formulated as follows: (4) DJP e =diag  C e MP f JP (5) S JP e= n g i=1d JP ei  ng i = 1 nc j = 1 dExp e ij +  ng i = 1 dJP ei (6) S j e=  n g i=1d Exp e ij  ng i = 1 nc j = 1 dExp e ij +  ng i = 1 d JP ei (7) R e=  R JP e R j e =εe  S JP e S j e (8) R =  e∈E R e (9) Q = R  231 i=1 R i . Page 7 of 17 Ohno et al. Economic Structures (2016) 5:28 2.4 Data WIO-MFA was conducted based on the Japanese 2005 IO table (Ministry of Industrial Affairs and Communications (Japan) 2009). The sectors of materials and steel mill products in the original IO table were disaggregated in detail and converted into a monetary unit description based on several statistics (Ministry of Economy Trade and Industry (Japan) 2006; The Japan Ferrous Raw Materials Association 2006; JOGMEC 2007). For more detailed information on the definition and disaggregation of the sector, see previous works (Nakajima etal. 2013; Ohno etal. 2014). Commodities considered in this analysis are listed in Additional file1. The trade data were organized based on the trade statistics of Japan (Ministry of Finance Japan 2005) by connecting the Harmonized System (“HS”) codes (i.e., international standard trade category codes) with the corresponding goods sectors in the IO table. Because the definitions of the sectors in the IO table were sometimes inconsistent with the HS codes, we could not perfectly adjust the amount of trade between the trade statistics and the values of the exports and imports of goods compiled in the IO table. Consequently, the exports from the IO table were allocated based on the ratio of the amount of trade by partner countries calculated from the records in the trade statistics. For partner countries, Nansai etal. (2014) were referred to. Inventories for the GHG emissions in each raw material production outside Japan were obtained from several sources of inventory data (Ecoinvent 2010; Eckelman 2010; Nuss and Eckelman 2014). Although the inventory of raw material production is varied with production sites, the homogenous inventory was applied in this study because of the lack of information on each site. In this study, we defined four raw materials of alloying elements imported by Japan: ore including concentrate, ferroalloy, pure metal, and others including matt and/or other chemical forms. As Nuss and Eckelman (2014) noted, in some cases the inventory data for each degree of fabrication were unavailable. Therefore, several inventories were estimated by referring to previous studies (Table1). By applying the obtained inventories, the GHG emissions associated with the raw materials imported by Japan were estimated. The responsibility for GHG emissions was then passed onto Japan as well as other countries and regions according to domestic demand in Japan and the destinations of the exported products. The GHG emissions in the fabrication of products in Japan were not taken into account in order to focus on only the impacts associated with metal production which tend to directly affect the environment in metal mining and producing countries and regions. Table 1 Inventories forGHG emissions inthe production ofalloying elements resources Mainly referred to Ecoinvent (2010) a Referred to the inventory for the concentration of each metal b Referred to the inventory for chromite c Estimated based on Eckelman (2010) d Assumed as Na2Cr2O7 e Assumed as nickel matt t/t‑CO2eq Ore Ferroalloy Pure metal Others Mn 0.01a1.00 2.60 – Cr 0.02b1.90 26.7 4.80d Ni 3.82c9.20 10.9 4.36c,e Mo 2.62a2.62a2.60 – Page 8 of 17 Ohno et al. Economic Structures (2016) 5:28 3 Results 3.1 Domestic flows ofalloying elements In 2005, 636, 635, 250 and 29kt of manganese, chromium, nickel, and molybdenum were imported, respectively, in the form of virgin sources. These were mainly consumed in steelmaking to produce steel mill products from crude steel by employing alloying elements. Accompanying steel mill products, alloying elements are widely distributed through the international supply chain. Indeed, in addition to the imported alloying elements, alloying elements contained in domestically generated steel scrap are utilized in steelmaking. Consequently, the actual flow of alloying elements is greater than that in the imported masses. Given the above, this study discusses the balance of alloying elements in the flow based on the imported masses. The masses of alloying elements remaining in Japan were calculated by subtracting the total exported masses of alloying elements in Japan from the imported masses instead of subtracting the total exported masses from the total consumed masses. 3.1.1 Manganese The top 10 usages of manganese are shown in Fig.2 for steel mill products (left-hand side) and other products (right-hand side). By separately showing the mass of exports and domestic consumption, we can distinguish the mass of manganese exported from that remaining in Japan. Because manganese is a commonly used element in steelmaking for deoxidation as well as alloying (Nakajima etal. 2008), carbon steel mill products, which require moderate a concentration of manganese (i.e., <1%), occupy 68% of the manganese consumption among steel mill products because of their large volume of production. This large consumption of manganese in carbon steel makes it stay in Japan rather than being exported as steel mill and other products. This is because carbon steel mill products are mainly consumed as construction materials domestically: about 230 kt (36% of manganese derived from imported virgin sources) of manganese was exported to other countries as products. In addition, 18 kt of manganese was exported as raw materials such as ferromanganese. 3.1.2 Chromium The main chromium-consuming steel mill products are stainless steel materials, structural alloy steel, and heat-resistant steel as shown in Fig.3 (left-hand side). A large part of these are fabricated into various products domestically, about half of which are exported Fig. 2 Top 10 usages of manganese in steel mill products (left) and other products (right) Page 15 of 17 Ohno et al. Economic Structures (2016) 5:28 research using multi-regional IO tables covers global trade (Lenzen etal. 2012; Dietzenbacher etal. 2013; Tukker etal. 2013). However, a detailed flow analysis for specific metals, especially non-base metals, requires a high-resolution IO and disaggregation of metal sectors to avoid the flow of metals being aggregated and unable to be distinguished from each other even for Japan who has one of the highest resolution of IO table. In this sense, multi-regional IO tables, which tend to have limited number of sectors for both metals and industrial activities owing to the necessity to homogenize the size of the IO tables for each region, or joint IO tables of a lot of regions with keeping the original sizes of tables, are unsuitable for our purpose. Therefore, to focus on the detailed flow of alloying elements, we selected this approach and demonstrated the trade of specific substances by using the presented snapshot. In terms of data limitations, we cannot trace the flow of alloying elements associated with second-hand goods because of the lack of trade data for them. Consequently, in addition to the limitation in the adjustment of Japanese IO sectors and HS codes in the trade statistics, this data shortage may cause us to underestimate the real flows. In this regard, we just traced the flow of alloying elements in products produced in 2005, omitting the associated flow of second-hand products. 5 Conclusion In this study, the flows of steel alloying elements in Japan and exports of Japanese products were obtained by means of the WIO-MFA model and by taking data from the trade statistics. Although the content of tiny metals such as alloying elements in highly fabricated products tends to be aggregated and/or ignored, this study covers the detailed content and flow of four alloying elements in order to consider the environmental impacts of the use of each metal separately and thus provide more precise implications. Based on the flow, the responsibility for GHG emissions during metal mining and production was estimated and its distribution among countries and regions in the supply chain calculated. Focusing on four alloying elements in the Japan-oriented supply chain allowed us to describe the role the country plays in the supply chain. We found that Japan has been a large importer of metal resources as well as a distributer of metals through its product exports. However, this activity has also been driven by consumers of Japanese products. Therefore, the development of eco-friendlier systems and processes with the aim of reducing the environmental impacts associated with metal consumption should be discussed not only in Japan but also in other countries that share the burden of responsibility. Authors’ contributions HO derived results and led the writing of this article. KM developed calculation method used in this study. KN supported the calculation and evaluation of the results of metal flows. KN provided the methodology and data for the analysis with a global scope. YF and TN planned the study and interpreted the implication of the results and the developed method. All authors read and approved the final manuscript. Additional files Additional file1. List of commodities considered in the analysis. Additional file2. Top 10 countries in terms of accompanying mass of allying elements with steel mill products and other products except for raw materials. Page 16 of 17 Ohno et al. Economic Structures (2016) 5:28 Author details 1 Graduate School of Engineering, Tohoku University, Miyagi 980-8579, Japan. 2 Graduate School of Environmental Studies, Tohoku University, Miyagi 980-8579, Japan. 3 Center for Material Cycles and Waste Management, National Institute for Environmental Studies, Ibaraki 305-8506, Japan. 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