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TNO report TNO 2014 R10231

Topical paper 10: Assessment of historical resource efficiency improvements in the aluminium industry

Date 3 February 2014 Author(s) Ester van der Voet, Lauran van Oers, Ruben Huele

Institute of Environmental Sciences CML Leiden University

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Study name Assessment of Scenarios and Options towards a Resource Efficient Europe 054.01783

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TNO report | TNO 2014 R10231

Topical paper 10: Assessment of historical resource efficiency improvements in the

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Contents

1 Introduction .............................................................................................................. 4

2 Production and use of aluminium .......................................................................... 5

2.1 Development of global and EU aluminium production .............................................. 5

2.2 Use of aluminium ..................................................................................................... 10

3 Energy use and GHG emissions of aluminium production............................... 14

3.1 Energy use in aluminium production ....................................................................... 14

3.2 GHG emissions of aluminium production ................................................................ 17

3.3 Energy use and GHG emissions related to aluminium in the built environment ..... 22

3.4 Conclusions of Chapter 3 ........................................................................................ 25

4 Resource efficiency indicators for aluminium in the built environment ......... 26

4.1 Aluminium consumption per capita .......................................................................... 26

4.2 Recycling rates and the ratio secondary/primary production .................................. 27

4.3 Energy intensity of aluminium, primary and secondary ........................................... 28

4.4 GHG intensity of aluminium, primary and secondary .............................................. 30

4.5 Aluminium intensity in construction and the built environment ................................ 32

4.6 Contribution of aluminium to total energy use and emissions of the built environment ............................................................................................................. 33

5 Future developments ............................................................................................ 34

5.1 Trends and resource efficiency improvement options ............................................. 34

5.2 Towards a closed loop economy for aluminium ...................................................... 35

6 Conclusions ........................................................................................................... 41

6.1 Conclusions on development of aluminium production and use, and use in built environment ............................................................................................................. 41

6.2 Conclusions on resource and eco-efficiency of aluminium use .............................. 41

6.3 Outlook and Options to improve .............................................................................. 42

6.4 A closed loop economy ........................................................................................... 43

7 References ............................................................................................................. 44

Appendix 1: Documentation on the dynamic MFA model for aluminium, as used for the calculations in Chapter 5 ................................................................................ 47



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Backgrounds of the project: Assessment of Scenarios and Options towards a Resource Efficient Europe The Europe 2020 Strategy, endorsed by the European Council in June 2010, establishes resource efficiency as one of its fundamental flagship initiatives for ensuring the smart, sustainable and inclusive growth of Europe. In support of the Flagship, the Commission has placed a contract with TNO, CML, PE and AAU/SEC for a project with the following aims. It should identify inefficient use of resources across different sectors and policy area’s at meso- and macro level and then quantitatively asses potentials and socio-economic and environmental effects of efficiency improvements, both from singular as system wide changes, up to 2050. The Built environment is focus area. The core methodology is a hybrid modelling approach: identifying improvement options, their costs and improvement potential at micro/meso level, and to feed them into a macro-model (EXIOMOD) to assess economy-wide impacts of improvement scenarios. Stakeholder engagement via workshops is an important part of the project. The project started in January 2012 and will end in December 2013. To inform stakeholders, during the project some 8-10 ‘Topical papers’ will be written. The aim is to get feedback on crucial elements of the scenario modelling with stakeholders. This document is forms one of the topical papers.



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1 Introduction

Aluminium is presently one of the most widely used metals worldwide. It has many useful applications, for example in construction, in transport, in power distribution and in packaging. Most of those applications have a very long life span. Aluminium, like most metals, has a rapidly increasing demand on the world market. As a consequence, world production is also increasing rapidly. The growth, both of demand and supply, occurs outside the EU. For the EU, the demand has stabilized and primary production does not grow either. The main reported sustainability problem related to aluminium is the high energy intensity of its production: primary aluminium production requires much energy, especially related to the smelting step where aluminium in its metallic form is produced from alumina, i.e.; aluminium oxide. Secondary aluminium production is much less energy intensive, but despite relatively high recycling rates still forms a limited fraction of supply. Aluminium production is also associated with high GHG emissions. These are mainly related to energy use, but also originate from other sources. This paper explores the resource efficiency of aluminium cycles in the past and present, with specific attention for aluminium applications in the built environment. It also explores some options for increasing resource efficiency. In Chapter 2, the production and use of aluminium in the world and EU will be treated. Chapter 3 deals with environmental pressures: the energy use, the carbon emissions and GHG emissions of the aluminium sector. Chapter 4 is dedicated to specifying some resource efficiency indicators for aluminium. In Chapter 4, some options for increasing resource efficiency will be identified and roughly assessed.



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2 Production and use of aluminium

2.1 Development of global and EU aluminium production

2.1.1 Global primary aluminium production Total global aluminium production rises, as is shown in Figures 1 and 2.

Figure 1 Global primary aluminium production by continent, 1973 – 2012

Source: International Aluminium Institute (2013)

The rise of Chinese production is very notable: in about 15 years time this has increased from very little to almost half of the world production, with China as the biggest aluminium producer by far. Probably these developments also reflected the demand in these areas. China is presently building up its infrastructure and expanding its car fleet, using a lot of aluminium in the process. Aluminium world production grows more rapidly than that of other bulk metals. Figure 2 shows this.



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Figure 2 Relative global production growth of metals, 1950 – 2010, indexed 1950.

Source: USGS primary production data

2.1.2 Primary aluminium production in Europe In Figure 3, European primary production is depicted.

Figure 2 Relative global production growth of metals, 1950 – 2010, indexed 1950.

Source: International Aluminium Institute (2013)

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The production in Western Europe has remained rather constant over the period 1973 – 2012. Reported Eastern European production has come up since the mid-1990s, it has peaked in 2008 and since then has leveled of as well (actual production probably occurred also before 1995). Figure 4 shows the primary production in EU27 countries. The time series is rather shorter. Large European production countries outside the EU are missing, most importantly Norway and Iceland. These countries apparently are responsible for more than half of European production. The EU’s biggest producer, Germany, has decreased its production significantly. In other EU countries, the decline has been more gradual, or the production is stable. From Figure 3 and Figure 4 together, it can be concluded that most of Europe’s production occurs outside the EU27. Two significant producers are Norway and Iceland, part of Western Europe but not of the EU.

Figure 4 Primary aluminium production in the EU27

Source: European Aluminium Association (EAA), 2013

2.1.3 Secondary aluminium production Estimates of secondary aluminium production vary widely. The IAI estimates a total amount of 46 Mt (or Gg) "remelted" aluminium at a primary production of 44 Gg worldwide in 2011 (IAI, 2012). The USGS estimates a secondary production of 12 Gg in 2007 (Menzie et al., 2010). The GDA, another aluminium industry association, estimates a number around 8 Mt for the period 2004-2010, as is shown in Figure 5 below. These numbers apparently are highly uncertain. One explanation for the variability is the definition: what is and what is not counted as "scrap"? Including industrial (new) scrap might lead to the conclusion that secondary production is already quite high, but it is the recycling of scrap from stocks-in-use (old scrap) that is relevant for the development towards a closed loop society. In our calculations in Chapter 5 of this report we will therefore focus on old scrap. According to IAI, around 11 Gg of old scrap is recycled in 2011. This seems to be in the same range as the other two estimates, therefore, we will use that number in Chapters 3 and 5.



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Figure 5 Primary and secondary production, worldwide, 2006 – 2010

Source: Gesamtverband der Aluminiumindustrie (GDA), 2013

Important reasons for this discrepancy could be that most important aluminium applications have a long life span (30-50 years). The built-up of the societal stock of aluminium has lifted off only after WWII. This implies many aluminium applications are still in stock and have not reached the waste stage yet, therefore, have not yet become available for recycling. Therefore, in the present situation, even if all generated aluminium scrap would be recycled, this still could not supply a major part of the demand. Secondary production in EU countries is shown in Figure 6.

Figure 6 Secondary aluminium production in the EU27




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The larger primary producers are France, Germany and Spain. Largest secondary producers are France, Germany and Italy. Even more interesting is the conclusion that the EU’s secondary production is larger than primary production. The share of secondary production therefore is much larger in the EU than in the world. It is, however, not growing, at least not in the period 2004 - 2010. It is also not declining, while primary production is. Presently, secondary production provides 60-70% of the total.

2.1.4 Aluminium balances Figure 7 shows the aluminium balance of the EU27, which can be used to derive consumption from data on production, export and trade.

Figure 7 Aluminium balance for the EU27


Apparent consumption is calculated as import + production – export. It can be seen that the apparent aluminium consumption is larger than the production, implying that these countries import most of the aluminium rather than producing it themselves. As is also true for other resources, especially metals, Europe appears to be a net importing region, relying on production elsewhere. The recent increase in apparent consumption is not met by an increase in production, but is mainly supplied by an increased import. Another interesting figure is provided by the scrap balance, as depicted in Figure 8.



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Figure 8 Scrap balance of the EU27


The balance, represented by the net scrap import, is negative. This implies that the EU27 exports scrap to be treated or recycled elsewhere. The scrap balance is not specific for the applications of aluminium. Scrap from the built environment will be part of “old scrap”. There is no reason to assume it will be treated or traded any different from other types of old scrap. The conclusion of all of these data is that EU27 does not follow the global trend of rapid increase in production. Nor does it follow the global trend of rapid increase in demand. Supply and demand have been stabilized in the EU. Primary production has declined, while secondary production is stable at about 4000 Gigagram (Gg, 109 g, equals kilotonne, or thousand metric ton, or 106 kg). Secondary production is now larger than primary production. Both together supply around half to two-thirds of EU demand. The EU thus is a net importing region, with a relatively well developed secondary production. The EU is also a net exporter of scrap. We have not analysed the reason why primary production declines and why there is a net export of scrap. For primary production, it is likely that strict regulation and high energy prices in Europe have made investment in new production plants difficult. These argumente do not seem valid for the net export of scrap, but other market related reasons may play a role here. For an EU policy on more self-sufficiency on aluminium, it may be worthwhile to find answers to these questions.

2.2 Use of aluminium

2.2.1 Aluminium applications The most important applications of aluminium are the following: • In construction, for siding and window frames • In infrastructure, mainly for power cables • In transport, in cars, trains, airplanes • In packaging, especially beverage cans.



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Worldwide, the following estimates are provided of the annual flows that go into these applications (Graedel, IRP, 2011, Metal stocks in Society): • Construction: 25% • Infrastructure: 18% • Transport: 28% • Packaging: 13% • Other applications: 16%. These applications go into societal stocks with widely different life spans, from 50 years for buildings and infrastructure to several months for beverage cans. This has consequences for the possibilities to close cycles. Some very rough estimates exists of the size of such stocks, but the information needed to estimate how much aluminium will become available for recycling at what moment is lacking. A few estimates exists, based on dynamic MFA models, for individual countries, regions or cities. According to IAI (http://recycling.world-aluminium.org/home.html) around three quarters of the accumulated aluminium production of 1000,000 Gg is locked in stocks-in-use. This leads to an estimate of 750,000 Gg. A more precise estimate of IAI is 662,900 Gg in 2009 (IAI, 2010). Liu & Miller estimate a global stock-in-use of 90 kg/cap for 2010, or 630,000 in total. Graedel (2011) estimates a present day global per capita stock-in-use of aluminium of 80 kg Al/capita, with an average 35 kg/cap for developing countries and 350-500 kg/cap for developed countries. For Europe, he estimates exist of 199 kg/cap in 2004. Liu & Müller (2013) show a variation in stock-per-capita size within Europe of 100 – 600 kg/cap, with high stocks especially in North Western Europe. Taking the 80 kg/cap and a world population of 7 billion, this would imply a total global stock-in-use of aluminium of 560 billion kg or 560,000 Gg, about 11 times the present annual inflow. This stock will some day become waste and then becomes available for recycling. Estimates of how much and when have to be based on dynamic MFA stock modeling: the outflow out of stock equals the inflow at the year t – L, L being the life span. Life spans vary from a few months (packaging) to 50 years (applications in the built environment), therefore, stock modeling must be done for individual stocks. It is essential to do this to make dependable forecasts of future secondary aluminium production and, therefore, roads towards a closed loop society. However it is not possible based on the presently available information. This is one of the major knowledge gaps that need to be addressed, not just for aluminium but for all metals, or rather for all materials in applications with a long life span. Time series of aluminium end uses are available for the USA. This is shown as an illustration in Figure 9.



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Figure 9 Aluminium applications in the USA.

Source: USGS

In the USA, most applications are rather stable. The great riser is transportation: the use of aluminium in cars. For Europe, these trends are probably similar. For the world, the other applications will still be on the rise.

2.2.2 Aluminium in the built environment Aluminium is used in the built environment for a number of applications: door and window frames, roof and wall plating, shading systems, and in many smaller components. Worldwide, this is one of the two largest categories of use, and contains by far the largest stock of aluminium. The annual inflow into the built environment stock are estimated to be 25% of the total annual production (Graedel, 2011), or around 11,000 Gg/year. According to Chen & Shi (2012), 4,000 Gg of this occurs in China. As can be seen from Figure 9, this is 1000 Gg in the USA. In Europe, this is 2250 Gg (EAA, 2006). Time series information has not been found. Stock estimates are even more scarce, and certainly no time series are available. IAI (http://recycling.world-aluminium.org/home.html) estimates a stock-in-use in the built environment of 35% of the total stocks, or 262,000 Gg of the total 750,000. In China, this is the most rapidly growing stock, with an estimate of 11 – 25 kg/cap in 2005, or about 13,000 – 30,000 Gg in total (Chen & Shi, 2012). In the US, Chen & Graedel (2012) estimate a total stock-in-use of 490 kg/cap in 2009, and 155 kg/cap in the built environment. In Europe, assuming the same distribution over the stocks as worldwide, the stock-in-use of the built environment would be 42,900 Gg, or 60



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kg/cap. An estimate for Italy (Ciacci et al., 2013) is 150 kg/cap for the present building stock. This may indicate that the 60 kg/cap for Europe is a rather low estimate, and that it may rather go in the direction of 150 kg/capita as well, or 105,000 Gg. Figure 5 shows a level flow to construction for the USA. This might be the same for Europe. The construction stocks may be approaching saturation in those regions of the world. Worldwide, this is not happening yet. For China, Chen & Shi (2012) show a rapid build-up of the aluminium stock in construction, almost doubling even in the short period from 2000 – 2005. In other regions of the world such a growth may be expected as well. Liu & Müller (2013) see a steady growth of the global aluminium stock of 5-10 kg /cap per year, with no signs of slowing down. The stock in the built environment has a long life span, estimates are 30 – 50 years (Graedel, 2011). This implies that the present inflow will become available for recycling in 30 – 50 years. For a development in the direction of a closed loop economy, this is relevant information: it means that it will take time to get there. In Chapter 5, this will be elaborated further.



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3 Energy use and GHG emissions of aluminium production

3.1 Energy use in aluminium production

The energy use of primary aluminium production is high and is regarded as one of the main aspects in both the competitiveness and the sustainability of aluminium production. According to the IRP Global Metal Flows group, presently 7-8% of total global energy use is for metals production. Most of that goes to iron and steel production, but around 5 EJ or 1% of the global total is used for aluminium production. The mining and refining of bauxite to alumina (a combination of aluminium oxides and hydroxides) requires energy, but most energy is needed for the smelting process that transforms alumina into aluminium metal. Unfortunately, no time series were found for the energy use of secondary production. The energy intensity of secondary production is about 5-10% (5% for new scrap and 10% for old scrap) of that of primary production (Ecoinvent, ..) which means that at present the total global energy use for secondary production should be about 1% of primary production, therefore, 0.01% of global total energy use. It sidesteps the mining and refining step altogether, and since the material does not have to be reduced, the smelting energy can be much less. Energy used in production contributes to GHG emissions, but to what extent depends on the energy mix in question. For the refining of bauxite, most is heat and (therefore) most is fossil fuels. For the smelting process, it is mainly electricity, and here we see an increase of renewable energy sources. Nuclear and hydropower are often used sources. Figures 10 to 13 show the energy mixes for aluminium production. Note that the totals refer only to the companies that have reported and not to the total production. Present coverage is quite good, well above 90%, but in the past there are some gaps. Notably, Eastern European countries and China have joined the reporting only since late 1990s. Figures 10 and 11 show the energy mix of alumina production, for the world and for Europe.



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Figure 10 Sources of energy for the global production of alumina from bauxite

Source: International Aluminium Institute, 2013. NB China is included since 1998.

Figure 11 Sources of energy for the European production of alumina from bauxite

Source: International Aluminium Institute, 2013

Worldwide, especially coal is a rapid riser, in line with general global developments. In Europe, the main source is now gas. The sudden rise around 2005 is not due to a sudden rise in production or energy use, but to a larger coverage of reporting. IAI statistics for Eastern and Central Europe start only in 1996 and are still to a large extent based on estimates rather than reporting.

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Figures 12 and 13 show the electricity mix that is used for smelting, i.e. aluminium production from alumina, worldwide and in Europe.

Figure 12 Electricity mix for global aluminium production.

Source: International Aluminium Institute, 2013. NB China is included since 1998.

Figure 13 Electricity mix for European* aluminium production

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Figure 13 Electricity mix for European* aluminium production


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Electricity used for aluminium production globally is different from the average global electricity mix. Although the largest share is from coal, aluminium production is done with a relatively high contribution of hydropower. Aluminium smelters are often located in countries with a lot of hydropower. As energy and energy related GHG emissions are an issue, a significant share of Al producers apparently answer this challenge by using hydropower. Europe deviates even more from the global picture as can be seen in Figure 13, with a yet higher share for hydropower. Before 2005, the high share of nuclear power is remarkable – probably for similar reasons.

3.2 GHG emissions of aluminium production

GHG emissions from aluminium production originate from energy use, but also from other sources. A main source of GHG emissions is perfluorocarbons (PFCs), especially tetrafluoromethane (CF4) and hexafluoroethane (C2F6). These process emissions used to be the main contributors to GHG emissions but have been reduced significantly in most installations1. Figures 14 – 16 show the process GHG emissions for aluminium production in various European countries. In Figure 14, the total GHG emissions are depicted, in Figure 15 the CO2 emissions and in Figure 16 the PFC emissions.

Figure 14 GHG emissions of aluminium production, European countries

Source: UNFCCC

1 Gibbs et al. (2000): "Primary aluminium is produced using the Hall-Héroult electrolytic process, where the smelting pot itself acts as the electrolysis cell during the reduction process. When the alumina ore content of the electrolytic bath falls below critical levels required for electrolysis, rapid voltage increases occur, termed “anode effects”. Anode effects cause carbon from the anode and fluorine from the dissociated molten cryolite bath to combine, producing CF4 and C2F6. The frequency and duration of anode effects depend primarily on the pot technology and operating procedures. Emissions of CF4 and C2F6, therefore, vary significantly from one aluminium smelter to the next, depending on these parameters."



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GHG emissions have been reduced since 1990, in some cases considerably. In order to know what happened, we break them down into CO2 and PFC emissions.

Figure 15 CO2 emissions of aluminium production, European countries

Source: UNFCCC

In general, CO2 emissions have not been reduced – in some countries, a little, in other countries like Iceland, they are much increased. Therefore the overall GHG emission reduction must be due to PFC emission reduction.

Figure 16 PFC emissions of aluminium production, European countries

Source: UNFCCC



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This is confirmed by Figure 16, showing that indeed PFC emissions have been reduced to a large extent. The latter is responsible for the overall decrease of process related GHG emissions. Greenhouse gas emissions from energy can be calculated from the energy mixes specified above. That provides us with Figures 17 – 22.

Figure 17 GHG emissions from alumina production, worldwide


Figure 18 GHG emissions from alumina production, Europe




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Following the differences in energy mix, the differences between energy related GHG emissions between the world and Europe show clearly. The much larger emissions from electricity used for smelting, the production of aluminium from alumina, is shown in the next two figures, Figure 19 for the world and Figure 20 for Europe.

Figure 19 GHG emissions from aluminium production, worldwide


Figure 20 GHG emissions from aluminium production, Europe




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GHG emissions from smelting are dominated by coal as a source for electricity as well. How do the process emissions compare to the energy related emissions? Figure 21 and 22 show this, for the world and for EU27.

Figure 21 Aggregate GHG emissions related to aluminium production, world

Source: International Aluminium Institute, 2013 and UNFCCC

Figure 22 Aggregate GHG emissions related to aluminium production, Europe

Source: International Aluminium Institute, 2013 and UNFCCC



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Smelting is the largest emitting step in the process, although in the EU its importance has been reduced. Process emissions, as concluded earlier, used to be important as a source of GHG emissions, but have now been reduced significantly mainly by reducing PFC emissions. Worldwide, it is now a few percent of the total, still not negligible, but much less than energy related emissions.

3.3 Energy use and GHG emissions related to aluminium in the built environment

3.3.1 Aluminium in construction Aluminium is used in construction in various applications. Some isolated data exist on the aluminium density in the built environment, among others from Environmentally Extended Input Output Analysis such as used in Topical Paper 1. This provides a resource use of 2 – 12 g bauxite per m2 of new building, corresponding with 0.4 – 2.4 g/m2 aluminium, for the year 2000. Highest amounts are found in Central and Eastern Europe. TU Delft has done a study for EEA on aluminium in the European built environment (Boin & van Houwelingen, 2004), revealing an average aluminium use of 2.5 kg/m2 dwelling in Southern Europe, 2.1 kg/m2 in Central Europe and 1.8 kg/m2 in Northern Europe. This is only a minor part of buildings in general: 0.12 – 0.28 g/kg building. To assess the energy use and environmental impacts of construction materials and their applications, Life Cycle Assessment is used. LCAs are made in the EU within the framework of the Integrated Product Policy (IPP). Strategies used in the implementation of the IPP are the environmental product declarations (EPD) and Ecodesign. EPD is a strategy adopted for external communication and is committed to reducing the environmental impact of a product. EPDs such as those made on concrete, wood and metals such as aluminium (Leroy & Gilmont, 2006) are based on LCA and contain information associated with the acquisition of raw materials, energy use, content of materials and chemical substances, emissions into the air, land and water and waste generation. The aluminium industry works with EPDs. On the EAA website a procedure and tool can be found on how to perform an EDP for aluminium applications in windows (http://www.alueurope.eu/environmental-product-declarations/). An EPD for window applications is available at http://www.alueurope.eu/web-tool-verification-aluminium-windows/. Ortiz et al. (2009) give an overview of LCA studies related to construction. One of the more relevant of this is a study of Zabalza Bribián et al., (2011) which gives data on the embodied energy and CO2 intensity of building materials. Figure 22 shows the contribution of primary energy demand for the manufacture of the materials needed in the construction of 1 m2 (gross floor area) (Zabalza Bribián et al., 2011). Figure 23 shows the CO2 intensity of the manufacture of the materials used for construction of 1 m2 building.



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Figure 22 Contribution of primary energy demand for the manufacture of the materials needed in the construction of 1 m2 (gross floor area)

Source: Zabalza Bribián et al. (2011).

Figure 23 Contribution of CO2 emissions associated with the manufacture of the materials needed for the construction of 1 m2 (gross floor area)

Source: Zabalza Bribián et al. (2011).

Although aluminium constitutes less than 0.1% of the weight, it contributes 7.7% to total energy use of construction materials. Aluminium’s contribution to GHG emissions is lower, 2.3%, most probably due to the energy mix used for aluminium production which contains a large share of hydropower. Several LCA studies with regard to construction products have been performed, also including aluminium products. The study of Citherlet et al. (2000) is a comparison of window frames (wood, plywood, aluminium, PVC, wood-aluminium, plywood-aluminium) and shading systems (PVC roll shutter, fiberglass tissue roll blind, aluminium canopy, glass-integrated venetian blind. In this study, it is concluded that aluminium components in the window and glazing systems have the highest environmental impact for non-renewable energy consumption (MJ) and



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climate change (CO2 eq.) compared to the alternatives. Also for other impact categories, like acidification and photochemical ozone creation, the impacts for the aluminium alternatives are often the highest. This is not surprising, as these impact categories are, like GHG emissions, mostly related to fossil fuel use. The same is true for toxicity impacts: fossil fuels is a source of toxic metal emissions. In all, it can be stated that the impacts of aluminium in the toal of construction materials is related mostly to the very high energy intensity of aluminium as a material, and the fact that the major source of energy still is fossil fuels2.

3.3.2 Aluminium in the use phase of buildings Taking a life cycle approach, most emissions of buildings occur in the use phase due to heating, cooling and the use of electrical appliances. This is shown in various studies. A review of about 60 studies (Sartori & Hestnes, 2007) shows that for low energy consumption buildings (with good insulation, adequate orientation etc.) the proportion of embodied energy in materials used varies between 9% and 46% of the overall energy used over the building’s lifetime. For conventional buildings this proportion is between 2% and 38% (Zabalza Bribián et al., 2011). Other studies assert that in conventional buildings, located mainly in Northern and Central European countries, the embodied energy in materials is around 10-20%, while 80-90% corresponds to energy in the usage stage, and less than 1% to energy for end-of-life treatments (Kotaji et al., 2003).

2 For the allocation of burdens between the primary aluminium system and secondary aluminium system the study of Citherlet et al. (2002) uses the so called “recycled content approach”. In the waste treatment and LCA community there is however a debate on how to model the recycling of materials and in particular metals (Frischknecht, 2010; Atherton, 2007). The proposed methodologies can roughly be classified into two distinctly different approaches: 1. Recycled content approach (also known as the cut-off approach); 2. End of life recycling approach (also known as the avoided burden approach). In Frischknecht (2010) it is concluded that the choice of modelling is not given in by scientific soundness but rather by subjective value judgements. The two above mentioned model approaches seem to be a combined choice of recycling percentage and allocation method. The recycled content approach chooses the present fraction of secondary material (70% for aluminium) and the cut off method for allocation, which means that secondary aluminium is considered “burden free”. The end of life recycling approach chooses the end-of-life recycling rate (90% for aluminium) and the avoided burden method for allocation, which means that recycled aluminium is supposed to replace primary produced aluminium, and therefore the emissions related to primary production are subtracted from the system. It is clear that the second method leads to a much better performance than the first one: negative instead of zero emissions, and a higher recycled content. It is equally clear that the first method is closer to present reality, since secondary aluminium production in fact does not have negative emissions and the fraction of secondary production is presently not equal to the end-of-life recycling rate. In fact the choice of recycling percentage and allocation method are independent choices. The choice for the recycling percentage may be given in by value judgements. We believe that the sensitivity of the results for these value judgements best may be explored by scenario calculations in which the present situation is analyzed as a baseline while possible future options are explored to analyze hypothetical improvements, However, for a fair comparison between materials these future scenarios should be performed for all materials and all kinds of improvements, not only restricted to recycling rates. Next to the two mentioned allocation methods, cut-off and avoided burden, there is a third allocation method, namely partitioning, which can be based on economic values (economic allocation) or mass (mass allocation) or other properties of the functional outflows. The choice is, again, arbitrary: there is no “wrong” choice and all are approved under ISO. According to ISO, a sensitivity analysis for allocation choice is indicated when it seems to have a large influence on the outcomes.



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It is not possible to allocate these emissions to aluminium, or any other specific construction material. EAA (undated) states that aluminium applications provide energy benefits in the use phase. For instance aluminium can be used in shading systems or day lightning systems, which include devices that enhance the daylight penetration and distribution into the room. In the literature no studies were found that include environmental analysis of use-phase environmental impacts related to such systems and alternative systems made of other materials. In the study of Citherlet et al. (2000) mentioned above, an analysis is made of the thermal balance of the utilisation phase of the different systems. Unfortunately the aluminium alternatives were not part of this analysis.

3.4 Conclusions of Chapter 3

From the energy and GHG emission analysis, we can draw the following conclusions: • Primary aluminium production uses 5 EJ worldwide, representing approximately

1% of total global energy use and roughly 10% of energy use for global metals production. It is, therefore, one of the largest energy using branches of industry in the world.

• Energy use of primary aluminium production increases, in roughly the same pace as primary aluminium production itself.

• Secondary aluminium production uses much less energy (5-10%) than primary aluminium production.

• Process related GHG emissions have been reduced significantly due to a reduction of PFC emissions. CO2 emissions have remained constant.

• Worldwide, energy related GHG emissions have risen considerably, with production. The energy mix of aluminium production however differs from the global average by especially a larger share of hydropower. This lowers GHG emissions per kWh used.

• Production increase mainly takes place in China. Most important electricity source there is coal, therefore, coal related emissions are expected to rise.

• In Europe, energy related GHG emissions from aluminium production are decreasing. Production remaining more or less constant, this indicates an increase in resource efficiency

• In the total of construction materials used for buildings, aluminium has a small share (<0.1%). However, in the energy and CO2 footprints, the its share is much higher: 7.7% and 2.3%.

• LCA studies show that aluminium in construction applications has a high environmental impact in various impact categories, compared to alternatives (see footnote 2).



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4 Resource efficiency indicators for aluminium in the built environment

In this chapter, we define and calculate a number of resource efficiency indicators for aluminium. These indicators can be used to monitor progress, but also to identify options to improve resource efficiency. They refer (1) to the use of aluminium itself, (2) to the ratio primary/secondary production in the supply, (3) to the energy intensity of aluminium production, (4) to the GHG intensity of aluminium production, and (5) to the use of aluminium in construction and the built environment.

4.1 Aluminium consumption per capita

A first resource efficiency indicator is the aluminium consumption per capita. Time series of total consumption are short, because of lack of data around secondary production, for which we have time series information only for the period 2004-2010. We therefore show just primary production, depicted below as Figure 25.

Figure 25 Consumption of primary aluminium per capita, worldwide, 1950-2010.

Source: USGS and UN.

This indicator has risen from below 1 to about 6 kg/cap in 2010. With secondary production added, we are now in 2012 at a level of consumption of 7.6 kg aluminium / capita per year.



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For Europe, the present level of consumption is around 20 kg/cap per year, for the EU27 this is around 23 kg/cap. To reduce environmental impacts from aluminium use, the only option that can be generated from this indicator is to reduce the use of aluminium altogether. This is not a recommendation, since it would imply replacing aluminium with another material. It cannot be concluded whether this would benefit the environment, or whether the environmental impacts related to the alternative would be equally large or more. Such recommendations can only be made on a case-by-case basis, and it would require an LCA study to establish whether such a substitution would lead to an environmental improvement. For the built environment, it has been concluded in Chapter 3 that aluminium compared to alternative materials for the same function often has a high environmental impact. From an environmental point of view, it would seem logical to recommend not to use aluminium when other materials with lower impacts can be used. However, there are other considerations that are not part of the analysis, such as the costs, the life span or the effort that has to be done for maintenance. Aluminium is a very low maintenance material. Any decision on using a specific material should be based on a complete argumentation, involving costs and utility as well as environmental aspects.

4.2 Recycling rates and the ratio secondary/primary production

These indicators show how far we are progressed toward a closed loop economy for aluminium. Recycling aluminium is a rather obvious way to improve resource efficiency, since it conserves resources as well as reduces energy requirements. End-of-life recycling rates for aluminium differ per application, but in general are quite high. Due to lack of data on waste generation, no time series could be constructed for the world. Some isolated sources provide the following information: • For applications in transport and the built environment, recycling rates in Europe

are 90 – 95%. For packaging, this is reported to be 25 – 75% (EAA). • Graedel et al. (2011) estimate that EOL recycling rates for aluminium worldwide

are above 50%. He quotes three estimates from three sources, being respectively 42%, 60% and 70%.

The share of secondary production from EOL recycling is of course much lower, around 20% (see section 2.1.3). For the EU it is much higher: 60-70% of production is presently secondary production. This is not just because secondary production is high, it is also because primary production in the EU27 is very low. Secondary production in the EU accounts for about 30-40% of total EU27 demand. Worldwide, obviously, demand can be assumed to equal supply, in regions of the world this is not possible. The recommendation following from this indicator would be to increase both the recycling rate and the ratio secondary/primary production.



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The EOL recycling rate can be broken down into recycling rates for specific applications. For the built environment, the EOL recycling rate is already very high, at least in Europe it is well over 90%.

4.3 Energy intensity of aluminium, primary and secondary

As is clear from Chapter 3, the aluminium industry uses a lot of energy. From these data and production data, the energy intensity can be calculated. It makes sense to differentiate between primary and secondary production, as well as between refining and smelting. Figure 26 shows the energy intensity of alumina production from bauxite (refining), Figure 27 the energy intensity of aluminium production from alumina (smelting). Both figures show data for Europe and for the world.

Figure 26 Energy intensity of alumina production*


*Data are re-calculated and expressed in kWh per ton aluminium, with the assumption that 1.9 kg alumina is needed to produce 1 kg of aluminium.



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Figure 27 Energy intensity of aluminium production from alumina


If these are added, they would provide the energy intensity of aluminium production: stable at about 23000 kWh/ton of aluminium from primary production. For secondary production, no time series data is available. However the estimate is that its energy intensity is about 5-10% of that of primary production – 5% for new scrap, 10% for old scrap. Several things can be concluded from this indicator: 1. The difference between the energy intensity of European and global primary

production is not large. 2. The trend is very slightly up for the first step and very slightly down for the

second step; overall the energy intensity has remained more or less the same for a period of about 30 years. This is rather remarkable in itself, as most industries have improved their energy efficiencies considerably over this period. Apparently this is not really possible for aluminium production, probably due to chemical/physical boundary conditions.

3. The amount of energy needed for the production of aluminium out of alumina is slightly more than double the amount of energy needed for the production of alumina out of rock. Bauxite mining is not shown in this picture, but the amount of energy needed is negligible compared to that of the other two steps.

This indicator cannot be broken down into the different applications of aluminium.



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4.4 GHG intensity of aluminium, primary and secondary

Greenhouse gas emissions, as stated in Chapter 3, are related to energy use but not directly, and are also originating from other sources. It is therefore relevant to distinguish GHG efficiency from energy efficiency. Figures 28 and 29 show the GHG intensity of the different processes involved in aluminium production, in the world and Europe. Data are re-calculated and expressed in kg CO2 eq. per kg aluminium, with the assumption that 1.9 kg alumina is needed to produce 1 kg of aluminium.

Figure 28 GHG intensity of aluminium production per process, world

Source: International AIuminium Institute, 2013

Figure 29 GHG intensity of aluminium production per process, Europe


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Process emissions in Europe and the world follow pretty much the same pattern: CO2 intensity remains constant, while PFC intensity is reduced significantly. For energy related CO2 intensity, we see a difference: in Europe, it improves but in the world, it increases. Altogether, this results in the trends in GHG efficiency as depicted in Figure 30.

Figure 30 Overall GHG intensity of primary aluminium production


Globally, energy related GHG intensity increases, due to the increasing share of coal in the energy package. In Europe, GHG intensity decreases and has halved in the last two decades. This is due entirely to changes in the energy mix, mainly the electricity mix. The energy mix is obviously important where GHG emissions are concerned. A clear recommendation therefore is to use more renewable sources of energy. In the EU27 this has already happened to a large extent. In the world, the trend is unfortunately opposite. Another source of GHG are PFC emissions in the aluminium production process. In the past, these were responsible for an important share of total GHG emissions. They have now been reduced in many countries, though not all. Obviously, this is something the aluminium industry can control, as opposite to the energy requirements of the process. A further improvement therefore can be reached by reducing PFC emissions also in places where they still are high. Figure 31 is an indicator that can be used to monitor progress on that road: the share of PFCs in process GHG emissions.

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Figure 31 Share of PFCs in process GHG emissions

Source: UNFCCC

These indicators can only be used for aluminium, and cannot be broken down into its various applications.

4.5 Aluminium intensity in construction and the built environment

Aluminium intensity in construction indicates the share of aluminium in the total of construction materials. No time series are available. Dynamic MFA models can be used to keep track of the amount of aluminium that goes into the built environment. However, that does not provide information on the rest of the construction materials. This may change when EE-IOTs that also include resource extraction become available, so for the future this can be an indicator to keep track of. Presently, this share is very small. At present it is not possible to define a “desired” level or even direction for this indicator, as aluminium is not a scarce material. Another indicator could be defined in the area of construction applications is the amount of aluminium going into the built environment compared to the total of all applications of aluminium. At present, this is about 25% (flow) and 35% (stock). Construction as an application is a good application from the point of recyclability: already now, recycling rates from this application are very high. It also has a very long life span. This indicates on the one hand that developments will be slow as this stock is slow to react to policy or market changes. On the other hand, it implies that the equilibrium stock will require only a small input of virgin material to replace lost



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material. This information is less difficult to collect. Time series of dynamic MFA should be made, which can probably be done with some reliability for aluminium.

4.6 Contribution of aluminium to total energy use and emissions of the built environment

As shown in Chapter 3, aluminium contributes much more than average to the energy use as well as GHG emissions related to the construction of a building. Using an indicator such as relative energy intensity (% energy related to Al / % weight related to Al in a building) could provide useful information. The same is true for relative emission intensity, not just related to GHG emissions but to other types of emissions as well. At the level of an individual building, it is possible to collect this information from LCA databases. At the level of the built environment of a country and the EU, it could be approached by using IOT information on resource use and emissions related to the construction sector. This information is available in EXIOBASE for the year 2000. No time series data are available, nor is it likely these will become available anytime soon. Although a relevant indicator, for the time being it will be difficult to report on a regular basis. When, in due time, time series of EE-IOTs will become available, this will become possible.



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5 Future developments

5.1 Trends and resource efficiency improvement options

If present trends are projected into the future, we can envisage a business-as-usual scenario for aluminium where the demand will still grow significantly for the next decades. JRC (…) estimates that the demand will be doubled in 2030 compared to 2003. The rise is very rapid now, due to the very rapid build-up of infrastructure in emerging economies. In developed countries, the demand appears to have stabilized: in the EU it appears not to have grown anymore since around 2000. It is expected that this will happen for the world as a whole as well, somewhere in the future, especially when the world population also stabilizes. We then can imagine a situation where the stocks of aluminium no longer have to be built up but also reach an equilibrium. Demand for aluminium is then linked to the maintainance of the stock. In that situation, the annual outflow of waste out of the stock equals the annual inflow. Below, some projections are made to provide an order-of-magnitude estimate of such an equilibrium situation. These are linked to options to improve resource efficiency in aluminium production. From the above, the following options can be distilled: 1. Reduce the use of aluminium altogether, or reduce the virgin input requirement 2. Increase the share of secondary production – towards a closed loop economy

for aluminium 3. As energy efficiency of primary production cannot be increased, improve energy

related emissions by changing the energy mix 4. Improve process emissions. Ad 1. As stated before, any substitution of another material for aluminium must be checked on life cycle resource use and life cycle impacts. It is not at all apparent that alternative materials overall do a better job. Another option in this area is to increase the life span of applications. On the one hand, it will take longer to reach the equilibrium situation. On the other hand, however, it will reduce demand given the equilibrium stock. Ad 2. This has to be the major thing to achieve, as it is the only thing that really can reduce energy requirements by the sector. But it will take time, it is not something that can be realized overnight. Increasing the share of secondary production worldwide is not possible in the near future, since a major increase in demand is still ongoing. In the EU, the demand is not growing anymore already for a decade. This means it would now in principle be possible to start closing the cycle. In fact, this is already an ongoing process: secondary production in the EU is now larger than primary production. With some effort, a closed loop economy for the EU is not too far away. An area of concern is that the EU is a net importer of aluminium, and a net exporter



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of scrap. Also, the secondary production is not increasing very much, the reason the share increases is that primary production goes down. In the EU as well as worldwide, we can start getting ready for the closed loop economy by preparing for large amounts of aluminium entering the waste stage: these amounts must be recycled to obtain a closed loop economy. Even when an equilibrium is reached, it will not be possible to completely close the cycle. Some primary input is still needed. Ad 3. Worldwide, we see that the opposite is happening now, with all of the increase in coal-based China. For the Europe the share of renewable energy is already very large – even so, it can always be increased. However, the EU relies on import. This means that the “footprint” emissions for EU consumption look less favourable due to the high fossil fuel content in the global energy mix. Ad 4. PFC emission reduction has already improved GHG intensity considerably. Nevertheless, it can still be further improved. Added to that we see that global reporting for GHG emissions is incomplete. China, for example, does not report to UNFCCC. Their PFC emissions therefore are not part of the picture. Improving reporting therefore is a clear recommendation to make.

5.2 Towards a closed loop economy for aluminium

From the previous, it is apparent that a closed loop economy for aluminium has great benefits, both for resource conservation and for environmental impacts. In fact, a shift towards secondary production is the only option to significantly reduce the energy use related to aluminium production. Aluminium recycling rates are already quite high for most of the applications. However, secondary production is presently not providing a large share in total supply. This is due to the fact that demand is still rising rapidly. The societal stock of aluminium is still building up. Only when the stock is built up, an equilibrium can be reached in inflows (demand) and outflows (waste), and secondary production can catch up with demand. How far away are we from such an equilibrium, what will it look like, and what could be consequences for energy requirements? Below, a quick-and-dirty estimate is made, depending on some facts and many assumptions, to illustrate and provide an order-of-magnitude picture. Such an estimate ideally should be made by using dynamic MFA. Both time and data are lacking to do that here, therefore, a simpler approach of calculating the steady state situation is made. Implicit assumptions for a steady state situation are that population is stabilized, the stock-in-use has matured and therefore stabilized at a certain level, and the inflow into the stock (the demand) has stabilized as well. In the steady state, the outflow of discarded aluminium products out of the stock equals the inflow, implying that the inflow is at “maintenance” level. Material flow accounts of EU countries show that in the EU, contrary to the world as a whole, demand is not growing anymore. Since around 1998 it has remained at its present level of around 7500 Gg primary and 4000 Gg secondary aluminium,



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together 11500 Gg, or 23 kg/capita. We expect a somewhat lower equilibrium demand due to the maturation of the stock. We assume that the EU is reaching an equilibrium with an annual demand of 15 kg per capita. Worldwide the demand is now 45000 Gg or 7.6 kg/cap; our assumption is that this will rise to this same level of 15 kg/cap. With this assumption, and with an assumption on the life span of the stock-in-use and the size of the world population, we can now calculate the equilibrium situation. And from this, we can then calculate energy requirement. The assumptions are shown in Table 1, the results of calculations in Tables 2 and 3.

Table 1 Assumptions used to calculate equilibrium flows and stocks of aluminium

Equilibrium demand for aluminium Equals present EU15 demand, 15 kg/cap

Life span of stock Average of life spans of different applications, ranging from 0.5 to 50 years: 30 years

EU27 population Stabilizes at present level, 503 million

World population 7 Billion, 9 billion

Energy requirement for Al primary production

150 MJ/kg (estimates from 80 – 220 MJ/kg)

Energy requirement for Al secondary production

9 MJ/kg (estimates from 7.7 – 11 MJ/kg)

Table 2 Flows and stocks of aluminium, EU and world, 2011 and equilibrium

Present demand

(kg/cap)

Steady state

demand (kg/cap)

Present demand(Gg)

Steady state

demand (Gg)

Present stock-

in-use (kg/cap)

Steady state

stock-in-use (kg/cap)

Present stock-

in-use (Gg)

Steady state

stock-in-use (Gg)

EU27, 503 million

23 15 11500 7545 199 450 100097 226350

World, 7 billion

7.6 15 53000 105000 80 450 560000 3150000

World, 9

billion n.a. 15 n.a. 135000 n.a. 450 n.a. 4050000

Of course these assumptions may be off, but as an order of magnitude approach it makes sense. It seems that under these assumptions the worldwide demand will double to triple before reaching equilibrium, and worldwide stock will still grow an order of magnitude. Graedel estimates the current stock of aluminium per capita in more developed countries to be 350 to 500 kg, therefore, an estimate of 450 kg/cap does not seem excessive. What about the time involved in reaching such an equilibrium? Is it possible to reach a 90% secondary production in 2050? At global level, the absolute amount of total aluminium consumption is expected to increase from 53000 Gg in 2010 to 135000 Gg in the year 2050. Supposing these 135000 Gg of aluminium consumption in 2050 comes for 90% from aluminium in use, a flow of 121500 Gg recycled aluminium is needed, which under assumption of a residence time of 30



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years, would require a stock of 4 million Gg. The present stock being 560000 Gg, this implies that an increase in global stock with a factor 7 is needed to support an aluminium production that comes for 90 % from secondary alumimium. To supply such an increase, the global aluminium stock would have to grow with an average annual increase of 87000 Gg for the next 40 years, which seems impossible. An increase of secondary aluminium supply to 90% by 2050 therefore seems to be unfeasable. For a secondary supply of 50%, 67500 Gg of secondary aluminium will have to be produced annually in 2050, which would imply a stock of 2 million Gg, or 225 kg per caput in 2050. This would require an annual stock increase of 36625 Gg primary aluminium, which is still extreme but might not be impossible. We have put the assumptions to the test in model calculations. Figure 32 shows the development of the demand in the period 1950 – 2100 under the assumptions stated above. The demand in the past is approached by primary production, as only a very brief time series exist of secondary production. Demand in the future is based on the JRC estimate for 2030, and the above guestimated equilibrium demand of 135,000 Gg. The curve was set to fit. The amount of available old scrap was calculated using the different life spans of the different stocks. In Appendix 1, the specifications and assumptions of the model are presented. Two assumptions for recycling rates are presented as well in Figure 33: 90% and 50%, leading to the secondary supply curves as shown. The difference between demand and secondary supply then has to come from primary production.

Figure 32 Estimated demand and secondary supply of aluminium under various recycling rates

From Figure 32, it can be seen that it indeed takes a long time for secondary production to catch up with demand. The equilibrium state is reached around the year 2100, with demand leveling off roughly four decades earlier. In 2050, the maximum attainable secondary production fraction is around 50%.



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The next step then is to estimate what the energy requirements are of such an equilibrium situation. This will depend on the assumptions on recycling rates, as secondary production requires much less energy than primary production. Obviously, increased recycling of aluminium will reduce energy requirements and emissions. However, it is less obvious how much is to be gained by increased recycling and how much recycling can be realistically achieved. Here we explore the consequences of various assumptions by constructing some simplified models. To illustrate, we assume an energy requirement of 100 units per production of 1 unit of primary aluminium and en energy requirement of 5 units per production of unit secondary aluminium. Presently, the ratio primary aluminium versus recycled aluminium is about 5:1. The production of 100 units of aluminium will have required 8400 units of energy. Decreasing the ratio of primary aluminium to recycled aluminium from 5:1 to 1:9, while keeping total output constant, will reduce the energy requirement to 1450 units, which is about 17% of the current energy requirement. Therefore, a large benefit is theoretically possible. The next question is, what is the energy requirement of the regime sketched in the above? A crucial number here is the fraction of demand that will be met by secondary production. Without increased recycling, such a demand would require 21000 units of energy, while an increase of production of secondary aluminium to 90% of the total will require 3693 units, which is 44% of the current requirement. In Table 2 below we have calculated with three recycling rates: 90%, 75% and 50%. This corresponds of course with three fractions of losses from cycle: 10%, 25% and 50%. Assumptions on energy requirements for primary and secondary production are listed in Table 1.

Table 2 Equilibrium demand for aluminium for the world and EU, total and primary under various assumptions for the EOL recycling rate.

Equilibrium total demand Gg/y

Equilibrium primary Al demand Gg/y

% Of present primary production

RR 90%

RR 75%

RR 50%

RR 90%

RR 75%

RR 50%

EU27 7545 755 1886 3773 44% 111% 222%

World, 7 billion

105000 10500 26250 52500 23% 58% 117%

World, 9 billion

135000 13500 33750 67500 30% 75% 150%

Energy requirement for Al production, EJ/y % of present energy requirement

Present RR 90%

RR 75%

RR 50%

RR 90%

RR 75%

RR 50%

EU27 0,2 0,2 0,3 0,6 86% 165% 297%

World, 7 billion

5 2,4 4,6 8,3 48% 92% 165%

World, 9

billion

n.a. 2,8 5,7 10,5 56% 113% 207%



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As can be seen, the assumptions on recycling rates make a large difference. With a RR of 90%, the world primary production can stabilize even at a lower level than the present. With lower RRs, the equilibrium level is higher than the present level. Figure 33 shows the trade-off between energy requirements and required stock size, depending on the recycling rate.

Figure 33 Trade-off between energy requirement and size of stock-in-use under varying recycling rate

In order to reduce energy requirements, the stock needs to grow to enable supplying a sufficient secondary production. To have the same energy requirement in 2050, the stock must grow with a factor 5. Any reduction means we need a larger stock. The process of stock growing is an autonomous one, therefore, such increases in stock are very well possible. Nevertheless, as estimated above, it takes time. Hastening the process by rapid stockbuilding does not help either – calculations for Beijing have shown that a sudden stock growth leads to an equally sudden waste flow years later, which may have dramatic consequences for various industries (Hu et al., 2010). In all, we can conclude the following: • A prerequisite for a closed loop economy is a steady state situation, where the

demand and the stock-in-use do not grow anymore. That also implies the population should stabilize.

• Under those conditions, a closed loop economy for aluminium is possible to a large extent; the demand for primary aluminium in the equilibrium situation may even be reduced worldwide despite a growth in stock as well as total demand.

• This has beneficial consequences for energy requirement: it can also be reduced significantly. The higher the recycling rate, the lower the energy requirements.



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• For a large share of secondary production, the stock needs to grow. Stockbuilding is an autonomous process, but it is not very well possible and moreover not recommendable to hasten it.

• For a large share of secondary production, EOL recycling rates need to grow as well. This is something that can be influenced and should be, since market conditions have a large influence on this development.

• A closed loop economy is possible, however, we do not expect this to happen in the near future. In 2050, a 50% secondary production may be obtained with some effort, but a 90% secondary production does not seem feasible at all, even under assumptions of a 90% recycling rate. By 2100 we might have reached such a state.

• In the EU, demand has already stabilized for about 15 years. Also, population does not grow anymore. Therefore, with some effort, it should be possible to arrive at a steady state, and therefore a closed loop economy, much earlier than 2100.

These conclusions are valid for aluminium in general, therefore, they also apply for aluminium in the built environment. As stated earlier, aluminium in the built environment is a very well recyclable stock, probably the best one. This is illustrated by the fact that EOL recycling rates are already very high, well over 90% in Europe. From the point of view of closing the loop, therefore, building applications are ideal. As far as we are aware there are no barriers that stop aluminium from being collected and recycled. The improvement that could be made, according to representatives of the industry, is to pay more attention to the separate collection of different types of aluminium (molded and cast). This would improve the applicability of recycled aluminium to be comparable with virgin aluminium.



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6 Conclusions

6.1 Conclusions on development of aluminium production and use, and use in built environment

From the production and use data, we draw the following conclusions: • Global primary aluminium production is increasing rapidly, presently mainly in

China. • EU primary aluminium production is decreasing, although the production in

Europe is stable : an increasing share of supply is coming from import. • Of total global supply, roughly 20% comes from recycling of old scrap. In the EU,

this is 60-70%. • Demand is growing worldwide, but has stabilized in the EU. • Production in the EU is supplying around half to two-thirds of EU demand. The

EU thus is a net importing region. • The EU is a net exporter of scrap. • Stocks of aluminium in use are large. The global average is 80 kg/cap, and the

range is between a few kgs/cap to over 600 kg/cap, averaging 35 kg/cap for developing countries and 350-500 kg/cap in developed countries.

• Construction is one of the largest applications of aluminium. Presently 25% of the inflow goes to the built environment, and around 35% of the stock-in-use resides in the built environment. Stocks are growing rapidly in emerging economies and much more slowly in developed countries.

6.2 Conclusions on resource and eco-efficiency of aluminium use

From the energy and GHG emission analysis, we can draw the following conclusions: • Primary aluminium production uses 5 EJ worldwide, representing approximately

1% of total global energy use and roughly 10% of the total amount of energy used for metals production worldwide. It is, therefore, one of the largest energy using branches of industry in the world.

• Energy use of primary aluminium production increases, in roughly the same pace as primary aluminium production itself.

• Process related GHG emissions have been reduced significantly due to a reduction of PFC emissions. CO2 emissions have remained constant.

• Globally, energy related GHG emissions have risen considerably, with production. The energy mix of aluminium production however differs from the global average by especially a larger share of hydropower. This lowers GHG emissions per kWh used.

• Production increase mainly takes place in China. Most important electricity source there is coal, therefore, coal related emissions are expected to rise.

• The difference between the energy intensity of European and global primary production is not large. If anything, primary production in Europe is less energy efficient.

• The energy intensity of primary aluminium production has remained more or less the same for a period of about 30 years. This is rather remarkable in itself, as most industries have improved their energy efficiencies considerably over this



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period. Apparently this is not really possible for aluminium production, probably due to chemical/physical boundary conditions.

• Globally, GHG intensity of primary aluminium production remains stable. On the one hand, the energy related GHG emissions go up due to the increasing share of coal in the energy package. On the other hand, PFC process emissions go down. In Europe, GHG intensity of primary production decreases and has halved in the last two decades. This is due to changes in the energy mix, mainly the electricity mix, as well as the reduction of PFC emissions.

• Secondary aluminium production uses much less energy (5-10%) than primary aluminium production.

• Aluminium constitutes < 0.1% of the weight of buildings, but contributes 7.7% to energy requirement and 2.3% to GHG emissions of the cradle-to-gate construction phase. The construction phase contributes 2 – 50% of the total cradle-to-grave energy use of buildings.

• Aluminium applications in the built environment often have a high life cycle impact compared to their alternatives. This is due mainly to the high energy intensity: not just GHG emissions but also emissions of acidifying, toxic and photochemical smog farming substances are related to the use of fossil fuels.

• It is not possible to support statements on the specific role of aluminium in the use phase of applications in the built environment.

6.3 Outlook and Options to improve

Expected developments are the following: • The global demand for aluminium will continue to rise over the next decades to

build up the infrastructure stock in developing countries. • Eventually the demand will stabilize as it already has in developed countries. • The secondary production fraction will then increase. • Energy requirement for primary production will not change, but as the share of

secondary aluminium production increases, total energy requirement for aluminium production will be reduced.

• This depends on the level where the demand and stock of aluminium will stabilize.

• Such forecasts should be made based on stock dynamics: dynamic material flow analysis models. This is perhaps the largest gap in knowledge there is, not just for aluminium but for all metals and materials in applications with a large life span.

Options to improve: • Any substitution of another material for aluminium must be checked on life cycle

resource use and life cycle impacts. • Increasing the life span of applications will reduce equilibrium demand. • Increasing the share of secondary production worldwide is the one option to

significantly reduce energy requirements of aluminium production. However this is only possible after stabilization of demand.

• In the EU, the demand is not growing anymore already for a decade. Therefore, with some effort, a closed loop economy for the EU is not too far away. An area of concern is that the EU is a net importer of aluminium, and a net exporter of scrap.



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• In the EU as well as worldwide, we can start getting ready for the closed loop economy by preparing for large amounts of aluminium entering the waste stage: these amounts must be recycled to obtain a closed loop economy. Even when an equilibrium is reached, it will not be possible to completely close the cycle. Some primary input is still needed.

• Renewable energy use will not change energy intensity, but it will lower the GHG intensity. Worldwide, we see that the opposite is happening now, with all of the increase in coal-based China. For Europe the share of renewable energy is already very large – even so, it can always be increased. However, the EU relies on import. This means that the “footprint” emissions for EU consumption look less favourable due to the high fossil fuel content in the global energy mix.

• PFC emission reduction has already improved GHG intensity considerably. Nevertheless, it can still be further improved.

• Added to that we see that global reporting for GHG emissions is incomplete. China, for example, does not report to UNFCCC. Their process emissions, PFCs as well as CO2, therefore are not part of the picture. Improving reporting therefore is a clear recommendation to make.

6.4 A closed loop economy

• A prerequisite for a closed loop economy is a steady state situation, where the demand and the stock-in-use do not grow anymore. That also implies the population should stabilize.

• Under those conditions, a closed loop economy for aluminium is possible to a large extent; the demand for primary aluminium in the equilibrium situation may even be reduced worldwide despite a growth in stock as well as total demand.

• This has beneficial consequences for energy requirement: it can also be reduced significantly. The higher the recycling rate, the lower the energy requirements.

• For a large share of secondary production, the stock needs to grow. Stockbuilding is an autonomous process; it is not very well possible and moreover not recommendable to hasten it.

• For a large share of secondary production, EOL recycling rates need to grow as well. This is something that can be influenced and should be, since market conditions have a large influence on this development.

• Applications of aluminium in buildings are beneficial for a closed loop society, as recycling rates can be high and life spans long.

• A closed loop economy is possible, however, we do not expect this to happen in the near future. In 2050, a global 50% secondary production may be obtained with some effort, but a 90% secondary production does not seem feasible at all, even under assumptions of a 90% recycling rate. By 2100 we might have reached such a state. In Europe, the equilibrium state may be reached sooner, since demand has already leveled off.



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Appendix 1: Documentation on the dynamic MFA model for aluminium, as used for the calculations in Chapter 5

The model is based on Graedel (2011, p 23) and Graedel (2010, p 22) with the following assumptions: • in the long run, total global demand is equal to total global production • the total global demand will be 87000 Gg/year in 2030, and will level off at

135000 Gg/year • the total global demand will develop following a sigmoid curve • fraction of yearly inflow going to separate uses is taken from Graedel (2010, p

31) • residence times of various separate use stocks are taken from Graedel (2010, p

31), with the exception of packaging for reasons of calculation • outflow is assumed to be equal to the inflow in the past, spanning the period

from maximum to minimum residence time, uniformly distributed around the mean delay.

• total stock is equal to the sum of the five separate socks at any moment. The model assumptions as table, after Graedel (2010, p 31) Use Fraction of

inflow to use Minimum residence time

Maximum residence time

Mean delay

Construction 0.25 30 50 40 Infrastructure 0.18 30 40 35 Transport 0.28 15 40 22 Packaging 0.13 1 2 1 Other 0.16 10 15 12

The program, written in Python, using numpy, pylab, scipy and pandas libraries, and the two files used for input are shown below. Program

#!/usr/bin/python from __future__ import division from pandas import Series, DataFrame import numpy as np import pylab from scipy.optimize import curve_fit import pandas as pd def sigmoid(x, x0, k, a, c): y = a / (1 + np.exp(-k*(x-x0))) + c return y def readin( filename): alu= 1.0 * pd.read_csv( filename, sep='#',

index_col='year')



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return alu def convolution( alu, Filter): DF = {} C = list() for use in Filter.keys():

c = np.convolve( alu.total, Filter[use]['f'],'same')

d = Filter[use]['delay'] C = d * [0] + list( c[0:-d]) DF[use] = C return DataFrame( DF, index = alu.index) def fit( alu, newstart=1973.0, newend=2050.0): cx = 10000.0 cy = 100000.0 xdata = 1.0* np.array( alu.index) ydata = 1.0 * np.array( alu.total) xdata1 = xdata/cx ydata1 = ydata/cy popt, pcov = curve_fit(sigmoid, xdata1, ydata1 ) x1 = np.linspace(1.0*newstart,

1.0*newend,(newend-newstart+1))/cx y1 = sigmoid( x1, *popt) x = cx*x1 y = cy*y1 P={'year': x, 'total': y} Q=DataFrame(P, columns=['total'],

index=P['year']) return alu, Q def makefilters( M): F = {} for use in M.index: F[use] = {}

n = 1.0 * M.ix[use]['Tmax'] - M.ix[use]['Tmin']

f = M.ix[use]['f'] F[use]['f'] = n * [ f*1/n] F[use]['delay'] = M.ix[use]['delay'] return F def run(): alu = readin( 'production.csv') xdata, ydata, x, y = fit( alu) pylab.plot( x,y) pylab.plot( xdata, ydata, 'o')



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def init(): M=pd.read_csv( 'model.dat', sep='#',

index_col='use') Fa=M['f']*F Smin = sum(M['f']*M['Tmin']) * F Smax = sum(M['f']*M['Tmax']) * F Mna=M['f']*M['Tmin']*F Mxa=M['f']*M['Tmax']*F T=DataFrame([Fa, Mna, Mxa], index=['f', 'Smin' ,

'Smax']) T=T.T S=DataFrame( T.sum(), columns=['sum']) S=S.T T = T.append( S) return M, T def summary(): P, Q = fit( alu, newstart=1950, newend=2100) C = convolution( Q, Filter) S=C.sum( axis=1) T = C T['total demand']=Q.total T['available old scrap']=S t = T.columns tt = [t[5],t[6],t[0],t[1],t[2], t[3], t[4]] TT = DataFrame( T, columns=tt) return TT def makegraph( T): graph = T.plot(fontsize=20, style=['-*', '-o',

'--', '-.', '-^', '->', '-+']) graph.legend(loc=2,prop={'size':20}) pylab.ylabel( 'Gg', fontsize=20) pylab.xlabel( 'year', fontsize=20) pylab.title( 'Model of total demand and

availability of scrap: 1950 - 2100', fontsize=20)

def recycling_rates( T): R=T[['total demand','available old scrap']] R['90% recycling rate']=0.9*R['available old

scrap'] R['50% recycling rate']=0.5*R['available old

scrap'] graph = R.plot(fontsize=20, style=['-*', '-o',

'->', '-^']) graph.legend(loc=2,prop={'size':20}) pylab.xlabel( 'year', fontsize=20) pylab.ylabel('Gg', fontsize=20) pylab.tick_params( axis='x', labelsize=18)



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pylab.tick_params( axis='y', labelsize=18) pylab.title( 'Aluminium demand and availabilit y

of secondary aluminium\ntwo scenarios of recycling rates', fontsize=20)

def presentation(): TT = summary() recycling_rates( TT) alu = readin( 'production.csv') F=135000 P=500e6 SpC=200 M, T = init() Filter = makefilters( M)

The file 'model.dat': use#f#Tmin#Tmax#delay old scrap from construction#0.25#30#50#40 old scrap from infrastructure#0.18#30#40#35 old scrap from transport#0.28#15#40#22 old scrap from packaging#0.13#1#2#1 old scrap from other#0.16#10#15#12 The file 'production.csv' year#total 1973#12017 1974#13463 1975#12326 1976#12629 1977#13793 1978#14152 1979#14560 1980#15390 1981#15116 1982#13544 1983#13967 1984#15781 1985#15486 1986#15583 1987#16497 1988#18577 1989#19138 1990#19514 1991#19650 1992#19455 1993#19724 1994#19147



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1995#19610 1996#20859 1997#21807 1998#22721 1999#23721 2000#24657 2001#24510 2002#26156 2003#27986 2004#29857 2005#31905 2006#33938 2007#38132 2008#39491 2009#36986 2010#41153 2011#43989 2012#45207 2030#87000 2050#135000 2100#135000

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