Category Archives: Papers

Material Flow Analysis in the EU-28

Material flow analysis of aluminium, copper, and iron in the EU-28

The EC Raw Materials System Analysis (MSA) was carried out in 2015 for 28 materials. The MSA study investigates the flows of materials through the EU economy in terms of entry into the EU, flows through the economy, stock accumulation, and end-of-life management, e.g., through disposal or recovery in the EU-28. The MSA study is a follow-up of the “Study on Data Needs for a Full Raw Materials Flow Analysis” , launched by the European Commission in 2012 within the context of the European Raw Materials Initiative’s (RMI) strategy. This strategy, which is a part of the Europe 2020’s strategy for smart, sustainable, and inclusive growth, aims at securing and improving access to raw materials for the EU.

The MSA is a key building block of the European Union Raw Materials Knowledge Base (EURMKB). MSAs are an important data provider for a variety of raw material policy knowledge needs, as also reflected in the Raw Materials Information System (RMIS). The RMIS aims to support the broad range of EU policy knowledge needs of, e.g., the EU Raw Materials (RM) Scoreboard, EU Critical Raw Materials (CRM) assessment, and EU trade negotiations. In addition, it also aims to support broader coordination beyond these needs of other EU level data and information on raw materials. For both of these EUKBRM/RMIS roles, MSA is a vital backbone. The MSA data sets contain key, material specific data and information that will support the development of a database for the RMIS. However, currently only 28 MSA studies exist (mostly for CRMs) which are quickly becoming outdated. So far, no MSA studies exist for some of the major metals (e.g., iron, copper, aluminium, zinc, or nickel) which are important to the EU economy, e.g., due to the large quantities in which find use as well as due to their use in special application, e.g., as alloying elements.

Against this background, this report presents, firstly, detailed MSA studies for aluminium (Al), copper (Cu), and iron (Fe) and discusses, secondly, possibilities for future MSA update and maintenance in the RMIS.

Overall, the results show that the EU-28 has a well-established industrial chain for all the three metals covering the major value chain steps (from extraction to end-of-life). However, modest natural deposits make the region strongly dependent on imports to meet the domestic demand of primary material. Only a small fraction of total primary metal input to processing in the EU-28 is supplied from domestic extraction ranging from 10% (Al) to 13% (Fe).

Demand-supply dynamics and product lifetime determine the accumulation of materials as in-use stocks and scrap generation at end-of-life. Iron, aluminium, and copper are used in large quantities (compared to other metals) and their major application segments have relatively long in-use lifetimes (e.g., 50-75 years for building and construction). In-use stock for the three metals in EU-28 were estimated at about 5,300 Tg for iron (or around 10 t per capita), 132 Tg for aluminium (around 260 kg per capita), 73 Tg for copper (around 140 kg per capita).

A consolidated recycling industry supplements primary supply of aluminium, copper and iron with inputs from secondary sources (i.e., new scrap and old scrap). In particular, old scrap recycling performance attests respectable end-of-life recycling rates (EOL-RR) for the three metals (i.e., 69% aluminium, 61% copper, 75% iron), but they are still far from “perfect” recycling.

In addition, not all old scrap collected for recycling is processed in the EU-28, with the region being a net-exporter of secondary material. Material loss in products at end-of-life and net-exports of secondary material forms constraint the closure of material cycles and prevent the implementation of a circular economy in the EU-28 requiring the adoption of resource efficiency strategies priority.

Because of its system-wide perspective on raw materials issues (encompassing all life-cycle stages of a raw material), the MSA provides an overarching data structure that could be based inside the RMIS database (DB) core to collect, store, and provide data also for other policy knowledge needs (i.e., EU CRM assessment, Circular Economy Monitoring, Trade, Minventory, RM Scoreboard). Flows/stocks parameters of the MSA can also be important to satisfy knowledge needs that may arise as a result of future policy needs, e.g., through resilience, determining urban stocks, and other emerging issues. Equally, complete MSAs can help in the quality assurance of the underlying mass balance/data and increasing harmonization of the various data sources – which cannot be guaranteed if only a partial picture exists.

Results from an assessment of data overlaps between MSA and other policy-related outputs show that current policy knowledge needs often require data on various flows related to the early stages of a raw material’s life-cycle. For example, a total of 12 flows (out of 40 in total) of the MSA are also required for the 2017 CRM assessment. Data on secondary raw materials are essential for current circular economy monitoring, but generally difficult to obtain without MSAs.

Possibilities for MSA update and maintenance range from partial data updates (harvesting data synergies with current policy-related outputs, e.g., the CRM assessment, Scoreboard, and Trade module in RMIS) to carrying out full/systematic MSAs for most candidate materials of the CRM assessment (through European Commission (EC) internal research projects and outsourcing via external contracts).

The full report is available here.

Supply Chain Viewer

Visualization of raw material supply chains using the EU criticality datasets

Europe relies on reliable and robust knowledge on materials stocks and flows to promote innovation along the entire value chain of raw materials. The EU criticality assessment examines, every three years, issues of supply risk and economic importance of a number of non-food and non-energy candidate materials from the perspective of the European Union. The most recent criticality assessment was published in 20171. The data collected during this assessment provide a good basis for further visualizations of material supply chains and structuring additional information in the form of material and country factsheets in the EU’s Raw Materials Information System (RMIS). This study uses the existing datasets from the 2017 EU criticality assessment to visualize 74 material supply chains and shows interconnections between them. Firstly, the data sets are rearranged into a simple graph with nodes representing the countries, materials, product applications, and sectors involved in materials supply and use. The weighted edges (links) represent relationships between them, i.e., the production of materials by countries and the flow of materials into product applications and subsequent economic sectors. Secondly, because mapping the critical raw materials data considers the links between countries, materials, product applications, and sectors, the resulting graphs can also be analysed using network statistics (based on their connectivity). For this, degree centrality (a count of the number of incoming or outgoing links of a node) is used to highlight more interconnected nodes (“key actors”) in the supply and use of materials. This allows, e.g., detection of countries providing a large number of different (raw) materials4, materials finding widespread downstream uses, or product applications relying on a large number of materials. Results show that arranging data according to the proposed data structure provides a simple, yet powerful, tool to map supply chains for 74 materials with only minor adjustments to the existing data sets necessary. The resulting graphs can be readily integrated into the RMIS to provide users with insights into the origin (countries) of materials and their downstream flows into product applications and economic sectors. Furthermore, overlaying multiple material supply chains with each other allows the visualization of interconnections between materials supply chains and to view the network from the perspective of individual nodes (e.g., a sector).

The full report is available here.

Development of a Sankey diagram of material flows in the EU economy based on Eurostat data

Europe relies on reliable and robust knowledge on materials stocks and flows to promote innovation along the entire value chain of raw materials. The concept of the circular economy, recently adopted by the European Commission, aims at maintaining the value of products, materials, and resources in the economy for as long as possible, and minimize waste generation. One of the prerequisites for better monitoring materials use across the whole life-cycle is a good understanding of material stocks and flows. The goal of this report is thus to show how readily available statistical information can be used to generate a Sankey diagram of material flows and their circularity in the 28 member states of the European Union (EU-28).

Despite several data challenges, it is possible to develop a visual representation of material flows and their level of circularity in the EU-28 as well as for individual member states for the period 2004 to 2014 (with future updates possible as new statistical data sets become available). The focus is on non-energy and non-food materials in line with the European Innovation Partnership on Raw Materials (EIP-RM). This includes material flows used for their material quality including, e.g., metals, construction minerals, industrial minerals, and biomass like timber for constructions or fibres for paper or textiles. Materials used for their energy content like fossil fuels, fuel wood, feed or food are excluded. A combination of regularly available data sources including economy-wide material flow accounts (EW-MFA) and EU waste statistics are used to generate a Sankey diagram showing the flows and net additions to stocks of four major material categories (metals, construction minerals, industrial minerals, and biomass (timber and products from biomass)).

In 2014, the turnover of non-energy and non-food materials in the EU economy is found at 4.8 Gt[1] (direct material input + recycling and backfilling). Recycled materials make up around 0.7 Gt (15%) of all materials used in the EU-28 in 2014. Socioeconomic stocks are growing in the EU-28 at about 2.2 to 3.4 Gt each year (net additions to stocks during the period from 2004 to 2014). For example, in 2014 around 51% (2.3/4.5 Gt) of all non-energy and non-food materials used domestically within the EU were added to stocks. Stock accumulation limits the potential for current recovery because material stocks are not immediately available for recycling (but will become available in the future when products providing useful services to the EU economy reach their end-of-life). In 2014, total waste generated from non-energy and non-food materials use in the EU-28 amounted to 2.2 Gt. Some 1.9 Gt of this waste was treated in the EU-28. The largest share of this waste (about 41%) was subject to landfilling operations. About 33% of the waste treated in the EU-28 in 2014 was sent to recycling operations (recovery other than energy recovery and backfilling) and 10% was used in backfilling. The EU is largely self-sufficient for construction minerals and industrial minerals, somewhat import dependent for biomass (for materials purposes), but highly import-dependent for metals.

Sankey diagrams for eight individual member states including Austria, Belgium, Czech Republic, Finland, Spain, France, Germany, and Italy are generated and compared with each other. Overall material throughput is highest for Germany, France, and Italy. Belgium’s economy depends on imports of a large number of raw materials, while several other EU countries domestically produce construction minerals and industrial minerals. Metals are imported by all member states although some EU countries (e.g., Finland) also have limited metal mining activities. In the eight EU member states examined, recycling and backfilling ranges between 11% and 68% at end-of-life (output side) and 6% and 27% when compared to overall material inputs (input side). Germany is used as a case study to show how the proposed visualization framework can be used to generate member state Sankey diagrams for multiple years.

Further research is needed to confirm these findings, fill in data gaps (e.g., trade in waste products), and better estimate selected flow parameters. However, the proposed assessment and visualization do provide a reasonable first picture of raw material uses and their flow magnitudes (by major material categories) in Europe, and how these evolve over time. The resulting Sankey diagrams will feed into the EC’s Raw Material Information System’s (RMIS) MFA module[2] (currently in development) to better visualize related material flows for the EU and at individual country level. The level of circularity can be measured considering different groups of raw materials. Because for materials used for energy purposes materials recovery is mostly not possible, we recommend including resource categories including fossil energy materials and biomass for food and energy purposes in future studies to obtain a more holistic picture of raw materials use in the EU.

Non-energy and non-food material flows in Belgium

The background report with the revised methodology is available from the EU bookshop.

[1] One gigaton (Gt) is equal to 1,000,000,000 metric tons.


2017 EU Critical Raw Materials List

Raw materials form the basis of Europe’s economy to ensure jobs and competitiveness, and they are essential for maintaining and improving quality of life. Although all raw materials are important, some of them are of more concern than others, thus the list of critical raw materials (CRMs) for the EU, and the underlying European Commission (EC) criticality assessment methodology, are key instruments in the context of the EU raw materials policy.

For the next update of the CRMs list in 2017, the EC is considering to apply the overall methodology already used in 2011 and 2014, but with some modifications. Keeping the same methodological approach is a deliberate choice in order to prioritise the comparability with the previous two exercises, effectively monitor trends, and maintain the highest possible policy relevance. As the EC’s in-house science service, the Directorate General Joint Research Centre (DG JRC) identified aspects of the EU criticality methodology that could be adapted to better address the needs and expectations of the resulting CRMs list to identify and monitor critical raw materials in the EU.

The goal of this paper is to discuss the specific elements of the EC criticality methodology that were adapted by DG JRC, highlight their novelty and/or potential outcomes, and discuss them in the context of criticality assessment methodologies available internationally.

Network Visualization of the 2014 EU Critical Raw Materials Results ((c) Philip Nuss, 2016)

The full publication is available open access from Resources Policy.

The background report with the revised methodology is available from the EU bookshop.

The 2017 EU Critical Raw Materials List is available from the DG GROWTH website.

Coupling of natural and anthropogenic elemental cycles

The characterization of elemental cycles has a rich history in biogeochemistry. Well known examples include the global carbon cycle, or the cycles of the ‘grand nutrients’ nitrogen, phosphorus, and sulfur. More recently, efforts have increased to better understand the natural cycling of technology critical elements (TCEs), i.e. elements with a high supply risk and economic importance in the EU. On the other hand, tools such as material-flow analysis (MFA) can help to understand how substances and goods are transported and accumulated in man-made technological systems (‘anthroposphere’). However, to date both biogeochemical cycles and MFA studies suffer from narrow system boundaries, failing to fully illustrate relative anthropogenic and natural flow magnitude and the degree to which human activity has perturbed the natural cycling of elements. We discuss important interconnections between natural and anthropogenic cycles and relevant EU raw material dossiers. Increased integration of both cycles could help to better capture the transport and fate of elements in nature including their environmental/human health impacts, highlight potential future material stocks in the anthroposphere (in-use stocks) and in nature (e.g., in soils, tailings, or mining wastes), and estimate anticipated emissions of TCEs to nature in the future (based on dynamic stock modeling). A preliminary assessment of natural versus anthropogenic element fluxes indicates that anthropogenic fluxes induced by the EU-28 of palladium, platinum, and antimony (as a result of materials uses) might be greater than the respective global natural fluxes. Increased combination of MFA and natural cycle data at EU level could help to derive more complete material cycles and initiate a discussion between the research communities of biogeochemists and material flow analysts to more holistically address the issues of sustainable resource management.

Coupling of Natural and Anthropogenic Cycles

The full publication is available open access from Science of the Total Environment.

Mapping supply chain risk by network analysis of product platforms

Modern technology makes use of a variety of materials to allow for its proper functioning. To explore in detail the relationships connecting materials to the products that require them, we map supply chains for five product platforms (a cadmium telluride solar cell, a germanium solar cell, a turbine blade, a lead acid battery, and a hard drive (HD) magnet) using a data ontology that specifies the supply chain actors (nodes) and linkages (e.g., material exchange and contractual relationships) among them. We then propose a set of network indicators (product complexity, producer diversity, supply chain length, and potential bottlenecks) to assess the situation for each platform in the overall supply chain networks. Among the results of interest are the following: (1) the turbine blade displays a high product complexity, defined by the material linkages to the platform; (2) the germanium solar cell is produced by only a few manufacturers globally and requires more physical transformation steps than do the other project platforms; (3) including production quantity and sourcing countries in the assessment shows that a large portion of nodes of the supply chain of the hard-drive magnet are located in potentially unreliable countries. We conclude by discussing how the network analysis of supply chains could be combined with criticality and scenario analyses of abiotic raw materials to comprise a comprehensive picture of product platform risk.

Product Platform Risk Analysis

Product Platform Risk Analysis

Germanium solar cell supply chain

Germanium solar cell supply chain

The full publication is available open access from Sustainable Materials and Technologies.

Network Analysis of Aluminum in the US Economy

Metals are used in numerous products and are sourced via increasingly global and complex supply chains. Monetary input–output tables (MIOT) and network analysis can be applied to intersectoral supply chains and used to analyze structural aspects. We first provide a concise review of the literature related to network analysis applied to MIOTs. On the basis of a physical input–output table (PIOT) table of aluminum in the United States economy in 2007, we identify key sectors and discuss the overall topology of the aluminum network using tools of network analysis. Sectors highly dependent on metal product inputs or sales are identified using weighted degree centrality and their hierarchical organization is explored via clustering. Betweenness centrality and random walk centrality (page rank) are explored as means to identify network bottlenecks and relative sector importance. Aluminum, even though dominated by uses in the automobile, beverage and containers, and construction industries, finds application in a wide range of sectors. Motor vehicle parts manufacturing relies on a large number of upstream and downstream suppliers to function. We conclude by analyzing structural aspects of a subnetwork for automobile manufacturing and discuss how the use of network analysis relates to current criticality analyses of metal and mineral resources.


Industry clusters and the physical flow of aluminum metal between each of the clusters in the 2007 US economy.

The full publication can be accessed at Environmental Science & Technology. The paper is published with two companion papers (see below) that describe how metal networks can be generated.

Ohno, H., Nuss P., Chen W.-Q., and Graedel T.E.  (2016): Deriving the Metal and Alloy Networks of Modern Technology. Environ. Sci. Technol. DOI: 10.1021/acs.est.5b05093.

Chen, W.-Q., Graedel T.E., Nuss P., and H. Ohno  (2016): Building the Material Flow Networks of Aluminum in the 2007 U.S. Economy. Environ. Sci. Technol. DOI: 10.1021/acs.est.5b05095

Environmental Implications of Metals Production

Compared on a per kilogram basis, mining and refining some of the exotic metals used in modern technology inflict a lot of damage on the environment. Compared on the basis of their global annual production, the cradle-to-gate impact of metals is still dominated by the old-school elements iron and aluminum. That’s one of the bottom lines from a comprehensive environmental analysis of 63 metals, published in PLOS ONE. A unique aspect of the study is that it teases apart the environmental impact of each element, even though many are mined or processed in combinations. The detailed analysis could help engineers design products that substitute more benign metals.


Cradle-to-gate greenhouse gas emissions per kg of metal and metalloid around 2008.

The full publication can be accessed for free at PLOS ONE or at the author page.


Criticality of Iron and Its Principal Alloying Elements

A study of iron and some of its major alloying elements (i.e., vanadium,chromium, manganese, and niobium), published in March 2014 in Environmental Science & Technology, investigates the criticality of these elements. Because of its widespread geological occurrence, iron was found at low supply risk. Chromium and manganese, both essential in steel making, display high vulnerability to supply restriction, largely because substitution or substitution at equal performance is not possible for all end-uses. The overall criticality is low for iron and modest for all alloying elements investigated.


Iron group criticality at the global level around 2008.

The publication is available at Environmental Science & Technology and the accepted version available free of charge here.


Life Cycle Thinking Informs Catalysis Choice and Green Chemistry

Catalysis is an enabling technology that can help promote significant energy savings in the chemical industry and provide products of crucial importance for sustainable development in the future. However, several studies within the area of green chemistry and sustainable catalysis promote new techniques and products as “sustainable” or “more environmentally benign” without taking a life cycle–wide perspective and quantifying their benefits and tradeoffs. Life cycle approaches such as life-cycle assessment or material flow analysis can be used (oftentimes even during process development) to quantify environmental impacts and resource flows, and thereby help to elucidate improvement options and avoid shifting of (environmental) burdens to other parts of the life cycle. Resource criticality assessments can provide additional information with regard to possible resource constraints.

This book chapter first introduces a number of system analysis tools used to quantify material stocks and flows and associated environmental effects along a product’s life cycle. Our focus is on environmental impacts, but a few references regarding social and economic approaches in the system analysis toolbox are also provided. We then continue to discuss the use of these tools in the context of sustainable (green) chemistry and catalysis. The chapter concludes with a case study applying life-cycle assessment to bioacrylics.

Greenhouse Gas Emissions of Bioacrylic Acid Production (Streamlined LCA)

Greenhouse Gas Emissions of Bioacrylic Acid Production (Streamlined LCA)

In book: Catalysis for Sustainability; Sustainability Contributions through Science Technology, Chapter 8. Life Cycle Thinking Informs Catalysis Choice and Green Chemistry, Publisher: CRC Press, Editors: Thomas P Umile, pp.177–194

Author Copy available here.