Life Cycle Assessment

Transcription

1 TVE Juni Examensarbete 15 hp Juni 2012 Life Cycle Assessment A Comparison Between a New Produced and a Remanufactured Rear Subframe Jennie Argerich Pär Holmberg

2 Abstract Life Cycle Assessment Jennie Argerich, Pär Holmberg Teknisk- naturvetenskaplig fakultet UTH-enheten Besöksadress: Ångströmlaboratoriet Lägerhyddsvägen 1 Hus 4, Plan 0 Postadress: Box Uppsala Recycling is an important part of the automotive industry and this thesis was made to examine the environmental impact from the production of a new produced rear subframe compared to a remanufactured subframe. A life cycle assessment has been done to investigate the inputs and outputs of the processes surrounding the new production and remanufacturing. The emissions from the processes have been categorized into four environmental categories. Based on the categories a comparison have been made to evaluate the environmental impact and conclude the differences between the two processes. Telefon: Telefax: Hemsida: Handledare: Ove Sers Ämnesgranskare: Joakim Widén Examinator: Joakim Widén ISSN: , UPTEC STS12 016

3 TABLEOFCONTENT 1. INTRODUCTION AND BACKGROUND LIFE CYCLE ASSESSMENT METHOD Goal and Scope Life Cycle Inventory Life Cycle Impact Assessment Interpretation GOAL AND SCOPE OF THE STUDY Goal Functional Unit System Boundaries Inside The System Boundaries Outside The System Boundaries Process Flow Chart Technological Coverage Geographical Coverage Data Collection Life Cycle Impact Assessment Methology Impact Categories Global Warming Potential Acidification Potential Photochemical Ozone Creation Potential Eutrophication Potential LIFE CYCLE INVENTORY- NEW PRODUCED SUBFRAME Primary Aluminium Bauxite Mining Alumina Production Anode Production Electrolysis The Cast House Input and Output Production of Primary Aluminium Secondary Aluminium Arrival and Pretreatment Smelting and Refining Casting Input and Output Production of Secondary Aluminium Profiling... 21

4 4.3.1 Extrusion Input and Output Profiling Transports New Produced Subframe Transports Primary Aluminium Input and Output Transports Primary Aluminium Transports Secondary Aluminium Input and Output Transport Secondary Aluminium Transport Extruded Subframe Input and Output Transport Extruded Subframe LIFE CYCLE INVENTORY- RENEWED SUBFRAME Refining Process of Used Subframes Energy Use During Refining Process Input and Output Refining Process Transports Renewed Subframe Input and Output Transports Renewed Subframe LIFE CYCLE IMPACT ASSESSMENT Characterization Factors and Equivalents Global Warming Potential Results Acidification Potential Results Photochemical Ozone Creation Potential Result Eutrophication Potential Results INTERPRETATION DISCUSSION CONCLUSIONS REFERENCES APPENDIX A - 100% Primary Aluminium APPENDIX B - 100% Secondary Aluminium APPENDIX C- Data Quality Check

5 1. INTRODUCTION AND BACKGROUND Subframes were first used in automobiles in the 1970s as an alternative to a full chassis. Separate front and rear subframes began to be used to reduce weight and cost. A subframe is used as a separate structure within a larger structure to carry the engine and the steering components. It is attached to the vehicle by bolts and its main purpose is to spread the loads of the chassis over a large area and to isolate vibration from the rest of the vehicle. It provides added comfort as it dampens vibrations and other forces generated by the engine. The subframe makes it possible to construct steering components and engines in different locations and install them in the vehicle in another location which reduces costs and transportation. This thesis concerns the rear subframe for the Volvo P2 program. The Volvo P2 program includes Volvo V70, Volvo XC70, Volvo S60, Volvo S80 and Volvo XC90. The rear subframe supports the rear suspension and is one of the largest components of the car s chassis. With its bushings it weight around 20 kg, of which 15 kg is made up of aluminum. The subframe itself consists mostly of aluminum and the bushings of steel and rubber. Rear subframes can be reused by being taken out of cars to be scrapped. The subframes then go through a process before they are sent back to Volvo where they are reused in new cars. (Ecris, Reducing Carbon Dioxide by 54 Tonnes) ECRIS is the commissioner of the thesis. Ecris was initiated in the mid 90 s as a research project involving Volvo Car Corporation, Stena Metall and Jönköpings bildemontering. The aim was to develop and improve the system of recycling cars from an environmental aspect. Now almost 20 years later, Ecris is a world leading company in remanufacturing and renewing products to the automotive industry. (Ecris). The collection of old subframes is made by ECRIS. Cars are transported to ECRIS in Jönköping where they are disassembled. The subframes of best shape are restored to their original condition before being sent to Volvo where they are reused. (Ecris). This thesis aims to quantify the environmental benefits of using a remanufactured subframe as compared to a newly produced subframe. Environmental impact in terms of emissions will be compared. The comparison will be done using a method called Life Cycle Assessment (LCA). LCA is a tool used to evaluate the environmental impact of a product. The product s entire life cycle is analyzed in an LCA. The assessment includes steps such as extraction of raw materials, manufacturing, transportation, maintenance and recycling or final disposal. There are different kinds of LCA studies such as gradle-to-grave, gradle-to-gate and cradle-to-cradle. In this thesis the cradle-to-gate- LCA will be used. A cradle-to-gateassessment includes all processes from the extraction of raw materials to the factory gate. The use of the product is not considered, nor is the maintenance or the disposal. There will be one cradle-to-gate- LCA done for a new produced subframe and one for the renewed used subframe. The results of both analyses will then be compared with 2

6 each other and an interpretation of the results will be made. (Rydh, et al., 2002, s ) The thesis will start with a definition of the goal with the study. The goal will describe the reason of the study and what results are desired. The goal will be followed by the scope, which includes an explanation of what is included and excluded in the study and give the reasons of the decisions. Later on comes the inventory where all data is collected. The data will then be normalized, calculated based on the functional unit and divided into different categories where each category describes an environmental impact. Descriptions will be done on the chosen environmental impacts. They will be described shortly before the results of each category will be presented. (Rydh, et al., 2002, s ) Three kinds of results will be showed for the new produced subframe, due to the difficulties of deciding the current mix between new produced aluminium and recycled aluminium. 3

7 2. LIFE CYCLE ASSESSMENT METHOD Life cycle assessment (LCA) is a scientific method created to analyze the environmental impact of a product or a service. The International Organization for Standardization (ISO) has worked to standardize environmental practice methods in order to find a common objective method that all environmental analyses can follow. These standards are described in the ISO series. Among these standards is the LCA. The LCA quantifies the resources and environmental impacts of activities from the cradle to the grave used in the system to fulfill its function. An LCA is a systematic study that followed given steps developed by the ISO. (Rydh, et al., 2002, s ) ISO has set the following standards that an LCA study should follow, consisting of four main phases; 1) Goal and scope 2) Life cycle inventory 3) Life cycle impact assessment 4) Interpretation These phases are described in more detail below. Figure1,LifeCycleAssessmentMethod 2.1 Goal and Scope The LCA starts with determine the goal and scope of the study. The goal and scope contain the use of the study, the system boundaries, desired data and desired result. The goal of the study is to find an answer to the question raised in the study. This section should describe why the LCA is made and what the results will be used for. It should evaluate how extensive the study should be, and what environmental effects will be 4

8 studied, for example greenhouse gas emissions and energy use. These decisions control which results are desired. Depending on the use of the study various limitations and assumptions will be chosen. (Rydh, et al., 2002, s ) In order to compare different systems a common unit is used, called the functional unit. The functional unit is a measure that describes the function and its use. The functional unit defines what exactly is going to be studied and sets the unit that all material and energy flows are quantified with respect to. (Rydh, et al., 2002, s ) After the goal, purpose and functional unit are set the system boundaries are defined. System boundaries are indicated in the flow chart to illustrate the processes that should be included in the LCA. To determine the system boundaries is a very important part of the study. The system boundaries will affect the final outcome and should be assessed carefully. The system boundaries are determined by the use of the study, the assumptions made and what is considered relevant. (Rydh, et al., 2002, s ) The scope specifies the system boundaries such as geographical and technological. The geographical boundaries include for example infrastructure, transport and local waste management. 2.2 Life Cycle Inventory In the Life Cycle Inventory (LCI) an inventory is made of the materials included in the system surrounding the selected studied item. The materials and energy used in for example manufacturing and transportation are the system inputs. The LCI flow charts are created to describe extraction of raw materials, manufacturing of products and the collection of products. These flow charts show what is taken from nature and what is given back in the form of emissions and waste to land, air and water. The flow charts are used to get qualitative and quantitative data on the inputs and the products and byproducts generated by the product. (Rydh, et al., 2002, s ) The flow charts contain the inputs and outputs of the system for the studied item, focusing on the functional unit. The chosen functional unit and the system boundaries set can affect the result of the LCI and are therefore of great importance for the result of the study. (Rydh, et al., 2002, s ) 2.3 Life Cycle Impact Assessment The data collected from the LCI is interpreted in the Life Cycle Impact Assessment (LCIA) to analyze its potential environmental impact. The LCIA presents and describes what kind of environmental impacts are analyzed in the study. It also introduces the models and calculations that are used to obtain desired results. Data gathered from the flow charts in the LCI are sorted into different classes. Each class of data analyzes a particular type of environmental impact, for example Global Warming Potential. The data collected to examine a particular type of impact is converted using different equivalents to one common unit. The data are then summed to be evaluated from an 5

9 environmental perspective. A common example is when different types of emission are converted into the same unit by using carbon dioxide equivalents. (Rydh, et al., 2002, s ) 2.4 Interpretation In the interpretation phase the analyses made in the LCI and the LCIA are evaluated, which leads to conclusions and recommendations. In this phase, the question that is raised in the goal should be answered and the goal of the study must be fulfilled. The interpretation may recommend changes in the system process or changes in the choice of materials. (Rydh, et al., 2002, s ) In the interpretation phase the data quality is evaluated to see if it meets the requirements. Verification of data and calculations are made. The information and results that are obtained through the LCI and the LCIA are summarized in this section. Important issues raised by the results of the LCI and the LCIA are discussed. The credibility of the LCA study is evaluated. (Rydh, et al., 2002, s ) 6

10 3. GOAL AND SCOPE OF THE STUDY 3.1 Goal The goal of this study is to evaluate the environmental impacts in terms of emissions caused by the production of rear subframes for the Volvo P2 program. The environmental impact of production of new rear subframes will be compared with the impact of refined and reused rear subframes. Following four environmental impact categories will be studied for the two different processes; Global Warming Potential (GWP), Acidification Potential (AP), Photochemical Ozone Creation Potential (POCP) and Eutrophication Potential (EP). In order to make this comparison this study will contain life cycle assessments for two items, one for a new produced and one for a remanufactured. This thesis aims to answer the following question; How are the four chosen environmental impact categories affected by the new production of subframes compared with the renewed subframes? 3.2 Functional Unit The functional unit is a measure of the product s benefit and should be practically measurable. The functional unit of this study is set to the manufacturing of 400 subframes. This is chosen as the functional unit since Volvo every year order around 400 renewed subframes from ECRIS. Thus, the study will compare the environmental impact of the new production of 400 subframes to the remanufacturing of 400 subframes. Since this LCA is a cradle-to-gate assessment, the whole life from birth to death will not be considered. Instead the distribution center of Volvo in Gothenburg will be considered as the gate. The assessment will cover most processes from the extractions of raw materials to the distribution center. 3.3 System Boundaries The system boundaries define what is included in the assessment and what is not. This report s boundaries have been set based on similar projects. The boundaries include the processes which make the biggest environmental impact and exclude those that do not seem to have the same importance for the end result. 7

11 Figure2,SystemBoundaries Inside The System Boundaries The object of study consists mainly of aluminium. The LCA for the newly produced subframe includes following main processes: The production of primary aluminium, i.e. new produced aluminium. The production of secondary aluminium, i.e. recycled aluminium. The profiling of the rear subframe. The transports related to the new produced subframe that will be included in the calculations are; Transport of alumina oxide from Freemantle, Australia, to Hamburg, Germany, where the electrolysis occurs. Transport of pitch and petroleum coke from Port Arthur, Texas, to Hamburg. Transport of aluminium from Hamburg to Meschedes where the profiling is taking place. Transport of the finished subframes from Meschedes to Volvo distribution center in Gothenburg. The LCA for renewed subframe at Ecris includes the processes as follows: Extraction of used rear subframe. Renewal to green part. 8

12 The transports related to the renewed subframe that will be included in the calculations are; Collection and transport of used to Ecris. Transport of the refined subframe back to Volvo s distribution center. In the study of the renewed subframe the transportation of used cars to Ecris and the renewal process is included in the LCA. In the remanufactering process, the subframe goes through various machines. The energy use in this process for these machines will be calculated and taken into account Outside The System Boundaries What is not included in the study is the manufacturing of the machines used in the production of new produced subframes and the machines used in the recycling process. The energy required producing them and the extraction of the raw material they are made of are aspects that are excluded. Neither the maintenance of these machines is included. The bushings in the rear subframes are excluded in this LCA, since they do not differ in this comparison and are new manufactured in both cases, there is no reason to include them in the cycle. Although the weight of the bushings is taken under consideration for the transports related to the renewed subframe. The rear subframe is composed mostly of aluminium. Other elements are for example rubber and steel, but since these are the same for the newly produced subframe and the renewed subframe, they will not be considered. The production of the cathodes used during the electrolysis is excluded too. What differs for the newly produced subframe from the renewed one is the production of primary and secondary aluminium, the profiling and the transports Process Flow Chart In following flow charts an overview of the new production and renewal process of subframes is presented. Later, in the inventory part, each of the steps of these processes will be described more in detail. 9

13 Figure3,FlowChartNewProduced Subframeubframe Figure4,FlowChartRenewedSubframe 3.4 Technological Coverage The technological coverage for this thesis is distributed on a worldwide basis depending on the process. The technological coverage for this study is as follows; Primary Aluminium Production - Global average Data collected from IAI (International aluminium institute) 10

14 Secondary Aluminium Production - European average, may include some data from outside of Europe Data collected from CPM LCA Database Profiling - European average, may include some data from outside of Europe Data collected from CPM LCA Database Renewal of Rear Subframes - Sweden Data collected from Ecris - Producer of the renewed subframe, i.e. the green part. Inventory data for processes, material, fuels, energy and power was gathered mainly from CPM LCA Database. Additional data has been collected from similar studies. The fuel consumption and emissions during the transports has been calculated based upon average data gathered from CPMLCA database. The distances have been estimated through Google maps, data from Ecris and Portworld which is a website that calculates the route and distance between international major ports. 3.5 Geographical Coverage The geographical coverage for this thesis is as follows: Bauxite Mining, Alumina Production- Australia Electrolysis, Casting house- Germany Anode Production- Germany Secondary Aluminium Production- Germany Profiling of Subframes- Germany Renewal of Rear Subframes- Sweden 3.6 Data Collection To make various types of environmental analysis the study categorizes collected data in the following categories; Energy and fuel consumption Emissions to air and water Extraction of raw materials and usage of natural resources Usage of refined resources By products Residue All the data will be shown in tables listed with inputs and outputs. The tables will include what kind of input and output it is, the collected inventory data, the calculated data for the functional unit and which environment it belongs to. These tables will be shown after a description of the related processes. 11

15 3.7 Life Cycle Impact Assessment Methology Chosen environmental impact categories will be analyzed in the Life Cycle Impact Assessment (LCIA). The categories are selected with the aspect of their relativity to sustainability during the new production and refining of subframes. In the Life Cycle Inventory (LCI) each emission is investigated separately, unlike in the LCIA where all emissions are summed together. In each category, specific equivalents are used in order to make an interpretation of the results. (Rydh, et al., 2002, s ) In this LCA the results of the LCIA have been analyzed using the CML- method. It was developed at the Institute of Environmental Sciences at the University of Leiden in the Netherlands. The method relates emissions and energy use into different impact categories. Specific data have been collected in the LCI to analyze the selected environmental categories that are determined in the goal of this thesis. In the LCI- part all data is collected and in the LCAI- part it is interpreted. (Gabi Software) The following impact categories will be used; Global Warming Potential (GWP) Acidification Potential (AP) Photochemical Ozone Creation Potential (POCP) Eutrophication Potential (EP) 3.8 Impact Categories In this chapter the chosen environmental impact categories, and the underlying environmental problems, will be described briefly. The equivalents used in each category will also be presented Global Warming Potential To measure the effects on the global warming a measurement named GWP- The Global Warming Potential is used. CO 2 equivalents are used to be able to put different greenhouse gases into the same category. Various types of greenhouse gases are for example carbon dioxide, nitrous oxide, methane and ozone. (Epa) Greenhouse gases are gases in the atmosphere that absorbs and emits radiation. Without greenhouse gases earth s surface would have an average temperature around 33 C colder than today. The problem is though, that since the industrial revolution the use of fossil fuels has increased rapidly. Burning fossil fuels releases large amounts of carbon dioxide into the atmosphere. The heighten content of greenhouse gases in the atmosphere leads to increased absorption of the radiation emitted by the sun. More radiation sends to earth s surface and the natural greenhouse effect is intensified. This leads to a rise of the temperature on earth. (Epa) 12

16 3.8.2 Acidification Potential To calculate The Acidification Potential (AP) SO 2 - equivalents are used. Examples of acidifying emissions are SO 2, NO x and ammonia. Acidification is a process that is natural but made worse by human action. Acidification happens when nutrients like magnesium, potassium and calcium are replaced with acidic elements such as aluminum and hydrogen by leaching. The ph- value decreases when pollutions in the air convert to acids. (APIS, 2010) The acidification of soil, water, flora and fauna is one of the major environmental problems as it for example makes the soil unusable for agriculture. Acidification leads to increased aluminum (Al 3 +) in the soil which destroys the cell wall in the roots of the plant and inhibits the absorption of nutrients. The increased amount of Al 3 + kill animals and organisms in the soil and can leach into lakes and seas, it causes harm to the natural ecosystem in ways that forests, other plants and animals die. (APIS, 2010) Photochemical Ozone Creation Potential The Photochemical Ozone Creation Potential (POCP), is measured using Ethene (C 2 H 4 )- equivalents. POCP measures emissions that cause low level smog, which is a result of chemical reactions between NO x and volatile organic compounds(voc) in sunlight. Photochemical ozone, also known as summer smog occur in the troposphere. (Bre) Ground level ozone is caused by the use of vehicles, which emit large amounts of nitrogen oxides in warm temperatures and sunlight, in the cities. Ground-level ozone can cause health damage and harm to animals and plant life. (Bre) Eutrophication Potential The eutrophying effect to the environment is measured by using phosphate(po 4 3- ) equivalents. Eutrophication is a natural occurrence but may be increased by human action. Increasing of phosphorus caused by human makes plants grow abnormally fast and algae tend to take over the vegetation. (Miljo) The reason is that the algae, as they become more, take up more of the nutrients that are also needed by other plants and animals. When the algae die they fall to the bottom of the water. The decomposition process of the algae requires a lot of oxygen which leads to oxygen-poor water. The increased algal bloom also prevents sunlight from reaching further down under the water. The natural aquatic ecosystem gets damage since much of the important nutrients needed are left at the bottom when the algae die. At the bottom they don t receive the needed sunlight which prevents the photosynthesis of aquatic plants. As the photosynthesis produces oxygen, of carbon dioxide, water and sunlight, the lack of sunlight makes the water more and more oxygen-poor. (Miljo) 13

17 4. LIFE CYCLE INVENTORY- NEW PRODUCED SUBFRAME The usage of secondary aluminium in the automotive industry is increasing. Since the recycle rate for aluminium in the automotive industry is above 90%, it is natural to assume that 90% of the mix to the profiling is secondary aluminium and 10% is primary aluminium. Although, currently the part of primary aluminium is bigger since the cars that are recycled today were manufactured about 20 years ago, a time when aluminium in cars were not so common. On the ground of this, it is difficult to determine how much secondary aluminium that is used in the profiling of the new produced subframe. Due to this problem, three different cases have been simulated. (Mattsson, 2001, s ) In the first case an aluminium mix of 50 % primary aluminium and 50 % secondary aluminium is used in the calculations. This case should be close to the current situation and its inputs and outputs are presented in the inventory. To estimate the importance of the choice of aluminium source, the two other extreme cases create a sensibility analysis. One of them presents the emissions when 100 % primary aluminium and 0% secondary aluminium is used and the other presents vice versa. The inputs and outputs for these cases can be found in appendix A. Therefore both the extraction of aluminium and the recycle process of aluminium scrap are included in the study of the manufacture of new produced subframes. Aluminium does not occur freely in nature but is extracted from bauxite through different processes. (Britannica) These processes and their environmental impacts will be examined in this LCA. It will also include calculations of the environmental impacts and energy consumption during the recycling of aluminum, secondary aluminum. Other environmental aspects that will be taken into account are for example transport between different parts of the extraction process and the production. The term technosphere will be used as one of the categories. Technospere is a term for those parts of the earth's surface and its vicinity area which is under influence of technological processes. 4.1 Primary Aluminium The production of primary aluminium is a process which includes the stages of bauxite mining, alumina refining, electrolysis, and the casting into the primary aluminium ingot. The process starts with bauxite as the first input. Thereafter follows the alumina refining which results in alumina oxide, which becomes liquid aluminium throughout the electrolysis. The casting of the liquid aluminium into the ingot concludes the process. The production of anodes to the electrolysis is also included in this LCA since it makes 14

18 environmental impact that is needed to take under consider. The process of the primary aluminium production is shown in following flow chart. Figure5,FlowChartPrimaryAluminium Bauxite Mining Bauxite is the principal ore for aluminium and consists mainly of the mineral gibbsite, boehmite and diaspore. Bauxite is usually found beneath the earth crust and is mined in open pit mines. The bauxite is commonly extracted with explosives adjusted to local conditions. After the extraction the bauxite is refined and in some cases crushed to remove dust and impurities before shipped. (Mattsson, 2001, s.38-45) Alumina Production The alumina is extracted from the bauxite throughout the Bayer method. The bauxite ore is crushed in a grinding mill and dried to eliminate the humid. Thereafter the dried and crushed bauxite once again gets ground to a fine powder and gets a bigger reaction surface. The powder is stirred and dissolved in caustic soda within an autoclave, this makes the caustic soda to react and dissolve to sodium aluminate. The content in the autoclave gets transferred to a dilution tank and is diluted with lye. Insoluble compounds get separated in a thickener, for example red mud. After that the alkaline solution is cooled and aluminium hydroxide precipitates to a solid. The aluminium hydroxide is heated to , calcined, and decomposes to water vapor and aluminium oxide, i.e. alumina. (Mattsson, 2001 s ) 15

19 4.1.3 Anode Production The anodes that are needed in the electrolysis appear as mainly two types; Söderberg and Prebake. Söderberg uses one single anode which covers the most of the top surface in a reduction cell. As the anode is consumed during the process, anode paste, briquettes, feeds downward from gravity. The heat bakes the paste into a monolithic mass and enters the electrolytic bath. The prebake uses blocks of solid carbon. The blocks are suspended from steel axial bus bars which holds the anodes in place and leads the current for the electrolysis. (Mattsson, 2001, s.292) The process for producing briquettes and prebake blocks is the same. Petrol coke is calcined and blended with pitch to make a paste that is formed into blocks and briquettes. (Mattsson, 2001, s.292) Electrolysis The aluminium is recovered from the alumina throughout the Hall-Héroult electrolysis in a molten. Generally a molten which consists of alumina dissolved in cryolite. The temperature in the molten is around C and weakens the bonds between the oxygen and the aluminium atoms. When a DC-current is led through the molten, the bonds dissolve and create aluminium and oxide ions. In the smelter exists anodes and cathodes which attract the ions. The aluminium ions go to the cathode where they are reduced and transformed into floating metallic aluminium. The aluminium has a higher density than the electrolyte and sinks to the bottom of the smelter. At the anodes the oxygen combines with the carbon which the anodes are made of, the compound of oxygen and carbon becomes carbon dioxide and carbon monoxide which are led to a waste treatment. (Mattsson, 2001, s.42-47) The Cast House The liquid metal from the electrolysis is transferred to holding furnaces where the metal cools to just above the melting point. Herein the oxid and cryolite compounds separates from the molten in a slow process. The separation is slow since the density differences are very small. The molten is thereafter casted into ingots for further processing. (Mattsson, 2001, s.46-48) Input and Output Production of Primary Aluminium Table1,InputandOutputProductionPrimaryAluminium Input Inventory data Total for FU Units Environment Natural resources Bauxite ,452 kg Ground Fresh water 28,6 86,9154 m 3 Water Sea water 18 54,702 m 3 Water Coal ,747 kg Ground 16

20 Natural gas ,803 m 3 Ground Refined resources Caustic soda ,708 kg Technosphere Diesel oil 9,7 29,4783 kg Technosphere Heavy oil ,073 kg Technosphere Steel bars 8,9 27,0471 kg Technosphere Petrol coke ,572 kg Technosphere Pitch ,432 kg Technosphere Alloy additives 20 60,78 kg Technosphere Chlorine 0,036 0, kg Technosphere Al fluoride 16,4 49,8396 kg Technosphere Cathode C 8 24,312 kg Technosphere Calcined lime ,964 kg Technosphere Alumina ,997 kg Technosphere Aluminium (liquid metal) kg Technosphere Anode ,965 kg Technosphere Electricity ,52 kwh Technosphere Output By product Bauxite residue 21,3 64,7307 kg Technosphere Dross 11,7 35,5563 kg Technosphere Filter dus 0,55 1,67145 kg Technosphere Refractory material 5,4 16,4106 kg Technosphere SPL-carbon 4,8 14,5872 kg Technosphere SPL- refractory 4 12,156 kg Technosphere Steel 10,6 32,2134 kg Technosphere Other by-products 13,4 40,7226 kg Technosphere Emissions Gaseous Flouride 0,56 1,70184 kg Air Particulate Fluoride 0,49 1,48911 kg Air Particulates 9,2 27,9588 kg Air Nox 0,22 0,66858 kg Air SO 2 22,3 67,7697 kg Air Total PAH 0,32 0,97248 kg Air Benzo-a-Pyrene 2,6 7,9014 g Air CF 4 0,13 0,39507 kg Air C 2F 6 0,013 0, kg Air HCl 0,009 0, kg Air Mercury 0,4 1,2156 g Air CO ,744 kg Air CO ,897 kg Air Fresh water discharge 22,9 69,5931 m 3 Water 17

21 Sea water discharge 18,1 55,0059 m 3 Water Fluorides 0,32 0,97248 kg Water PAH 1,69 5,13591 g Water Oil and grease/hydrocarbons 0,92 2,79588 kg Water Suspended solids 0,32 0,97248 kg Water CH ,78 kg Air BOD 0,0024 0, kg Air HC 9,9 30,0861 kg Air NH3 0,023 0, kg Air Residue Bauxite residue ,644 kg Technosphere Alumina waste 2,6 7,9014 kg Technosphere Carbon waste 14,8 44,9772 kg Technosphere Dross 2,2 6,6858 kg Technosphere Filter dust 0,14 0,42546 kg Technosphere Refractory 2,3 6,9897 kg Technosphere SPL 13,2 40,1148 kg Technosphere Scrubber sludges 4,9 14,8911 kg Technosphere Other landfilled waste ,833 kg Technosphere Product Primary aluminium ingot kg Technosphere 4.2 Secondary Aluminium Aluminium is a metal that is suited for recycling. The loss of aluminium during the process is very small and the quality is very high. The high quality means that it can be used in the same way as primary aluminium and the process can be repeated virtually to infinity. The recycling process uses only about 5% of the energy that is used in the production of the primary metal. The process includes 5 phases, the arrival of the aluminium scrap, the pretreatment, the melting, the refining and the casting. (Mattsson, 2001, s.110) 18

22 Figure6,ProductionofSecondaryAluminium Arrival and Pretreatment The received scrap is checked for radiation which follows by weighing and material control. Thereafter the material gets sorted taking account to composition, form and the nature of the material. Finally a quality and an environmental assessment are made. The plastic, rubber and metal are separated by hand. Large pieces are shredded to smaller form and aluminium scrap is crushed and centrifuged. (Mattsson, 2001, s ) Smelting and Refining The pretreated aluminium scrap is smelted in salt bath furnaces. The added salt protects the metal from oxidation. Thenceforth the molten is transferred to alloying furnaces to add alloying elements. In the alloying furnaces the molten gets the final composition by the added alloying elements and is purified by nitrogen and chlorine. (Mattsson, 2001, s ) Casting The processed molten casts into ingot molds and gets packaged for delivery. (Matsson, S. (2001) s ) 19

23 4.2.4 Input and Output Production of Secondary Aluminium Table2,InputandOutputProductionofSecondaryAluminium Input Inventory data Total for FE Units Environment Natural resources Coal 95,4 289,9206 kg Ground Crude gas ,087 Kg Ground Crude oil 32,3 98,1597 Kg Ground Water 8 24,312 kg Water Refined resources Alloying additives ,081 kg Technosphere Aluminium Scrap ,53 kg Technosphere Chlorine 1,6 4,8624 kg Technosphere H2SO4 8 24,312 kg Technosphere HCL 0,2 0,6078 kg Technosphere Hydraulic oil 0,0075 0, kg Technosphere Light oil 0,088 0, kg Technosphere Lime 7,7 23,4003 kg Technosphere NaOH 1,6 4,8624 kg Technosphere Nitrogen 1,8 5,4702 kg Technosphere Salt 13,7 41,6343 kg Technosphere Electricity 143,2 435,1848 kwh Technosphere Output By product Al-Mg 0,86 2,61354 kg Technosphere Aluminium oxide ,641 kg Technosphere Iron scrap 12 36,468 kg Technosphere Non-ferrous metals ,638 kg Technosphere Emission Cl- 0,05 0,15195 kg Air Cl2 0, , kg Air CO 0,3 0,9117 kg Air CO ,239 kg Air Dust 0,29 0,88131 kg Air H2S 0,0028 0, kg Air HCl 0,45 1,36755 kg Air HF 0,0067 0, kg Air Hydrocarbons 2,6 7,9014 kg Air N20 0,0014 0, kg Air NH3 0,021 0, kg Air Nitrogen 2,5 7,5975 kg Air Nox 1,1 3,3429 kg Air PH3 0, , kg Air 20

24 SO2 2 6,078 kg Air Residue Ball mill dust 64,3 195,4077 kg Technosphere Dirt 1,9 5,7741 kg Technosphere Filter dust 13 39,507 kg Technosphere Refractory waste 2,1 6,3819 kg Technosphere Solid waste 3,4 10,3326 kg Technosphere Stones 4,3 13,0677 kg Technosphere Waste filter material 0,005 0, kg Technosphere Waste oil 2,7 8,2053 kg Technosphere Waster rubber 24,3 73,8477 kg Technosphere Waste sediment 3,4 10,3326 kg Technosphere Product Secondary aluminium ingot kg Technosphere 4.3 Profiling The subframes are assumed to be profiled by extrusion from a mix of primary and secondary aluminium. Since the part of the secondary aluminium increases every year it is hard to determine how the mixture looks today Extrusion The aluminium ingot gets heated to C and is placed in the extrusion container. The heated ingot is pressed through a matrix which has the form of the desired profile. The scrap from the process is remelted and used to extrusion again. In this thesis it is assumed that the aluminium part of the subframe is completely extruded. (Matsson, S. (2001) s.56-62) Input and Output Profiling Table3,InputandOutputProfiling Input Inventory data Total for FE Units Natural resources Environment Brown coal kg Crude oil kg Ground Hard coal kg Ground Natural gas kg Ground Water m 3 Ground Wood kg Water Ground Refined resources Alloyging additives 18,6 111,6 kg Technosphere Aluminium ingot kg Technosphere Ar-gas 0,53 3,18 kg Technosphere 21

25 Chlorine 0,081 0,486 kg Technosphere Fluxing agents 0,36 2,16 kg Technosphere NaOH kg Technosphere Nitrogen 0,3 1,8 kg Technosphere Paper and cardboard 3 18 kg Technosphere Plastics 2,1 12,6 kg Technosphere Refractory material 1,2 7,2 kg Technosphere Steel 0,9 5,4 kg Technosphere Electricity kwh Technosphere Output Emission CH4 2,2 13,2 kg Air Chlorides 2,7 16,2 kg Water CO 0,23 1,38 kg Air CO kg Air COD 0,003 0,018 kg Water Dust 0,69 4,14 kg Air HC 0,79 4,74 kg Air HCl 0,1 0,6 kg Air HF 0,01 0,06 kg Air NH3 0,0016 0,0096 kg Air Nox 1,6 9,6 kg Air Oil/grease 0,063 0,378 kg Water SO2 3,2 19,2 kg Air Suspended particles 0,33 1,98 kg Water Residue Hazardous waste 1,6 9,6 kg Technosphere Oil 1,7 10,2 kg Technosphere Sludge kg Technosphere Solid waste unspecified kg Technosphere Product Extruded aluminium profile kg Technosphere 4.4 Transports New Produced Subframe The transportation is an important factor of an environmental study. In this thesis there are multiple transports, especially long shipments of alumina and petroleum coke which are related to the production of primary aluminium Transports Primary Aluminium Australia is the world leading exporter of bauxite, thereof the bauxite is assumed to be extracted in Perth, Australia. The production of aluminium oxide usually occurs in the land where the extraction of bauxite is taken place hence so is assumed in this thesis. (AAC) The aluminium oxide is assumed to be shipped by a medium sized cargo vessel 22

26 to Hamburg, Germany. In Hamburg the electrolysis and the anode production are assumed to be done by Germany s largest primary aluminium producer, Trimet Alumnium. (Trimet) For the anode production, petroleum coke and pitch are needed, and they are assumed to be shipped to Hamburg from Texas, USA by a large cargo vessel. This is assumed since the global leading producer of petroleum, The Oxbow Corporation, is located in Texas, USA. (Oxbow) The produced aluminium is then assumed to be transported by a heavy truck to Meschedes, where the profiling of the subframes is done Input and Output Transports Primary Aluminium Table4,InputandOutputTransportsHamburg Meschede Input Inventory data Total for FE Units Environment Cargo Primary aluminium ingot 1 3,039 ton Technosphere Secondary aluminium 1 3,039 ton Technosphere Refined resources Diesel E class 1 0, ,9528 kwh Technosphere Output Cargo Primary aluminium ingot 1 3,039 ton Technosphere Secondary aluminium ingot 1 3,039 ton Technosphere Emissions CO 0,012 24, g Air CO ,392 g Air HC 0,012 24, g Air NOX 0, ,48064 g Air Particles 0,0023 4, g Air SO 2 0, , g Air Distance Hamburg-Meschede km Vehicle Heavy truck with international semi trailer, Euro 3 Environmental standard. Table5,InputandOutputTransportsFremantle Stade,Hamburg Input Inventory data Total for FE Units Environmental Cargo Alumina 1 5, Ton Technosphere 23

27 Refined resources Heavy oil 0, ,40127 kwh Technosphere Output Cargo Alumina 1 5, Ton Technosphere Emissions CO 0, , g Air CO ,034 g Air HC 0, , g Air NOX 0, ,77802 g Air Particles 0, , g Air SO2 0, ,85201 g Air Distance Fremantle-Stade, Hamburg km Vehicle Cargo vessel medium sized ( deadweight tonnes) Table6,InputandOutputTransportsPortArthur,Texas Stade,Hamburg Input Inventory data Total for FE Units Environmental Cargo Petrol coke and pitch 1 1, Ton Technosphere Refined resources Heavy oil 0, , kwh Technosphere Output Cargo Petrol coke and pitch 1 1, Ton Technosphere Emissions CO 0, , g Air CO ,6248 g Air HC 0, , g Air NOX 0, , g Air Particles 0,02 252, g Air SO2 0, ,53071 g Air Distance Port Arthur, Texas-Stade, Hamburg km Vehicle Cargo vessel medium sized ( deadweight tonnes) 24

28 4.5 Transports Secondary Aluminium Germany is a big producer of secondary aluminium and since the profiling is taking place in Meschede, Germany, it is natural to assume that the production of secondary aluminium also occurs in Germany. Hydro is the world leader on the aluminium recycling market and in this thesis it is assumed that the secondary aluminium received to the profiling is produced at Hydro s plant in Hamburg. (Hydro) The aluminium scrap that is used in the process of producing secondary aluminium is assumed to be collected from a recycling center in Hamburg. This collection is made by a heavy truck and the distance for the collection is estimated to 80 km. The secondary aluminium ingot is transported to Meschede by a heavy truck. The distance the truck is travelling from Hamburg to Meschede is 336 km Input and Output Transport Secondary Aluminium Table7,InputandOutputTransportsHamburg Meschede Input Inventory data Total for FU Units Environment Cargo Primary aluminium ingot 1 3,039 ton Technosphere Secondary aluminium 1 3,039 ton Technosphere Refined resources Diesel E class 1 0, ,9528 kwh Technosphere Output Cargo Primary aluminium ingot 1 3,039 ton Technosphere Secondary aluminium ingot 1 3,039 ton Technosphere Emissions CO 0,012 24, g Air CO ,392 g Air HC 0,012 24, g Air NOX 0, ,48064 g Air Particles 0,0023 4, g Air SO 2 0, , g Air Distance Hamburg-Meschede km Vehicle Heavy truck with international semi trailer, Euro 3 Environmental standard. Table8,InputandOutputTransportsRecycleCenter HydroPlant Input Inventory data Total for FU Units Environment 25

29 Cargo Aluminium Scrap 1 3,85953 ton Technosphere Refined resources Diesel E class 1 0, , kwh Technosphere Output Cargo Aluminium Scrap 1 3,85953 ton Technosphere Emissions CO 0,012 3, g Air CO ,4176 g Air HC 0,012 3, g Air NOX 0,58 179, g Air Particles 0,0023 0, g Air SO 2 0, , g Air Distance Recycle center-hydro plant 1 80 km Vehicle Heavy truck with international semi trailer, Euro 3 Environmental standard. 4.6 Transport Extruded Subframe Page The rear subframes are profiled and extruded in Meschede, Germany. In Gothenburg, Sweden, Volvo has a distribution center which the subframes are transported to and the center is considered as the end of life. The distance from Meschede to Gothenburg is estimated to be approximately 746 km. It is assumed that the transport of rear subframes from Meschede to Gothenburg is done with a heavy truck, with a max cargo of 18 ton, Euro 3 Environmental Standard Input and Output Transport Extruded Subframe Table9,InputandOutputTransportsMeschede Gothenburg Input Inventory data Total for FU Units Environment Cargo Rear subframes 1 6 ton Technosphere Refined resources Diesel E class 1 0, , kwh Technosphere Output Cargo Rear subframes 1 6 ton Technosphere 26

30 Emissions CO 0,012 53,712 g Air CO g Air HC 0,012 53,712 g Air NOX 0, ,08 g Air Particles 0, ,2948 g Air SO 2 0, ,96944 g Air Distance Meschede-Gothenburg km Vehicle Heavy truck with international semi trailer, Euro 3 Environmental standard. 27

31 5. LIFE CYCLE INVENTORY- RENEWED SUBFRAME In the inventory-part of the renewed subframes data is collected for the process of turning used subframes into renewed subframes. To calculate the emissions caused by the refining process the electricity use is measured. The sources of the electricity are estimated using a general Swedish power mix published in the CPMLCA database. The calculations of emissions due to the transportation of used subframes to Ecris and renwed subframes to Volvo will also be based on data published by the CPMLCA database. 5.1 Refining Process of Used Subframes Ecris remanufactures the rear subframe to a so-called green part. It means that Ecris restores the subframe to its original condition. The process starts with a complete rear chassi in a cassette. The subframe is extracted from the chassi and enters a blasting cabinet in which it gets blasted. After the blasting cabinet a close inspection is made to make sure that there are no cracks or other damages of the subframe. If the subframe is suited for remanufactering it moves along to a hot water bath before adding new bushings. Finally the renewed subframes are packed and are ready for delivery with the same warranties as a new subframe. (Ecris) Figure7,RefiningProcess 28

32 5.1.1 Energy Use During Refining Process In the refining process various machines are used. The subframe first passes a screwdriver machine with the effect of 500 W, the screwdriver process takes about 20 minutes. (Ove Sers, Electronic Interview, 2012) Next machine in the process is the blasting cabinet with an effect of 2000 W, a process that last for about five minutes. The last machine in the refining process is the washing machine. The washing machine s effect is 2000 W and the washing process takes three minutes. (Ove Sers, Electronic Interview, 2012) An impact wrench machine is used to separate the subframe from the car, which is attached by the car by bolts. It is assumed that the impact wrench machine has an effect of 800 W and the process takes approximately three seconds. (Ove Sers, Electronic Interview (2012)) Input and Output Refining Process Table10,InputandOutputRefiningProcess Input Inventory data Total fo FU Units Environment Refined resources Electricity 1 174,388 kwh Technosphere Used rear subframes 8000 kg Technosphere Output Emissions CO 0, , g Air CO 2 27, , g Air HC 0, , g Air NOX 0, , g Air Particles 0, , g Air SO 2 0, , g Air Product Renewed rear subframes 8000 kg Technosphere 5.2 Transports Renewed Subframe Ecris collect Volvo cars from various places in Sweden and bring them to Jönköping where the subframes are dismounted. An average distance for the trucks to drive during this collection is set to 150 km based on data from Ecris. The truck can hold 9 cars at each transport. (Ove Sers, Electronic Interview (2012)) To collect 410 subframes the truck must drive forward and backward approximately 46 times. It is estimated that one of 40 subframes do not make the test and is not suited for remanufacturing. Due to this, 410 subframes are needed to fulfill the functional unit of 400 subframes. 29

33 After the refining process the renewed subframes are sent to Gothenburg and Volvo s distribution center. The distance from Jönköping where Ecris is located to Gothenburg where Volvo is located is estimated to 15 km Input and Output Transports Renewed Subframe Table11,InputandOutputTransportsCollectionofUsedCars Input Inventory data Total for FU Units Environment Cargo Used subframes 1 8,2 ton Technosphere Refined resources Diesel E class 1 0, , kwh Technosphere Output Cargo Used subframes 1 8,2 ton Technosphere Emissions CO 0, ,2 g Air CO ,6667 g Air HC 0, ,2 g Air NOX 0, , g Air Particles 0, , g Air SO 2 0, , g Air Distance Collection used cars , km Vehicle Heavy truck with international semi trailer, Euro 3 Environmental standard. Table12,InputandOutputTransportsJonkoping Gothenburg Input Inventory data Total fo FU Units Environment Cargo Rear subframes 1 8 ton Technosphere Refined resources Diesel E class 1 0, , kwh Technosphere Output Cargo Rear subframes 1 8 ton Technosphere Emissions CO 0,012 14,1984 g Air 30

34 CO ,8 g Air HC 0,012 14,1984 g Air NOX 0,58 686,256 g Air Particles 0,0023 2,72136 g Air SO 2 0, , g Air Distance Jonkoping- Gothenburg 1 147,9 km Vehicle Heavy truck with international semi trailer, Euro 3 Environmental standard. 31

35 6. LIFE CYCLE IMPACT ASSESSMENT In the Life Cycle Impact Assessment (LCIA) part the data collected in the LCI is analyzed more deeply. The published graphs that will follow will show the effects of the chosen environmental categories, caused by the production of new subframes contra the renewable process of used subframes. For the new produced subframes three different scenarios will be presented. The first graph shows the environmental impacts of the selected categories when 50% of primary aluminum and 50% of secondary aluminum is used. It is estimated that this provide an approximate value of how much of each aluminum category that is used in the in automotive industry in the current situation. Two of the graphs are used to create a sensitivity analysis of the importance of choice of aluminium. One of these graphs will show the emissions emitted during the production of a new subframe when 100% of primary aluminium and 0% of secondary aluminium are used. Similarly, the other graph will show the emissions during the new production of subframes when only secondary aluminium is used. A fourth graph shows the emissions and environmental impacts of the recycling process made by Ecris of the renewed subframe. 6.1 Characterization Factors and Equivalents Equivalents shown in Table 13 have been used to convert various data into each environmental impact category. Table13,EquivalentFactors GWP 100 [gco 2 eq/g] AP [gso 2 eq/g] EP [gpo 3 4 eq/g] POCP [gc 2 H 4 eq/g] Emissions SO 2 1 NO X NH CO 2 1 CO 3 0,032 CH ,007 C 2 H 4 1 CHCl ,004 HC 11 0,416 32

36 6.2 Global Warming Potential Results Figure8,GWP results Results of the effect of the global warming are measured using CO 2 - equivalents. As graph 1 show, the production of primary aluminium is the major cause of emissions in the manufacture of new subframes, when it is assumed that an aluminium mix of 50% primary aluminium and 50% secondary aluminium is used. It is estimated that about 43.6 times more kg CO 2 is emitted in the new production of subframes contra the renewable process of used subframes, when this aluminium mix is used. If 100% primary aluminium and 0% secondary aluminium would be used in the new production 76 times more CO 2 would emit. A conclusion is that the less primary aluminum is used, the less impact has the manufacturing of new subframes on the global warming. This is mainly due to energy-intensive processes as the electrolysis but also because the long transports of alumina and petroleum coke. Although, even if the new produced subframes would be manufactured with exclusively secondary aluminium the CO 2 emissions would still be about 11 times higher than for the renewed subframe. This is mainly because of the necessity to re-melt and extrude, which are avoided in the renewal process. 33

37 6.3 Acidification Potential Results Figure9,AP results The most realistic case for the new produced subframe, where the parts of secondary and primary aluminium are equal, emits around 40 times more SO 2 -equivalents than the renewal process. The main reason why the difference is so large is because of the production of the primary aluminium and the transports related to it. As can be seen in the inventory data the primary aluminium production emits relatively large amounts of SO 2. The transport of bauxite and petrol coke, which are assumed to be done by cargo vessels, also emits large amounts of both SO 2 and NO x. The large amount of emissions during these shipments means that the transport makes the largest AP- impact in this case. The case with 100% primary aluminium shows this very clear and makes the amount of SO 2 - equivalents increase markedly to about 71 times higher than the renewal process of the used subframe. In the case with 100% secondary aluminium the transports make a smaller impact since the shipments with cargo vessels are avoided. Although both the profiling and the production of the secondary aluminium make a greater impact, the total amount of SO 2 equivalents are still about 9 times higher than the renewed subframe 34

38 6.4 Photochemical Ozone Creation Potential Result Figure10,POCP results The primary aluminium production is by far the largest contributor to C 2 H 4 emissions. The chart results and the inventory data for the primary production conclude that the big difference is because of the, in comparison, high emissions of CO and HC. With 100% primary aluminium the amount of C 2 H 4 equivalents is by far larger, about 680 times larger the renewed subframe. This means that it is still a very big difference in the mixed case as well, the new produced subframe would emit as much as 359 times more C 2 H 4 equivalents. With 100% secondary aluminium in the new produced subframe the C 2 H 4 emissions decreases markedly because the small emissions of CO and the absence of HC. Still, the renewed subframe emits about 28 times less C 2 H 4 - equivalents than the new produced. For the renewed subframe, the transports are related to it is the biggest factor for emissions. But since the transports make a relatively small impact on the POCP, the renewed subframe hardly make no C 2 H 4 emissions at all. 35

39 6.5 Eutrophication Potential Results Figure11,EP results On the contrary from the POCP, the transport has a large impact on the EP. As can be seen in chart Table 12 the transport is by far the greatest contributor to the emission of SO equivalents. This is mainly because of the emissions of NO x. This makes it natural that the case with 100% primary aluminium also has the most emission of SO 4 3 equivalents, due to the long shipments with bauxite and petroleum coke. The new produced subframe would in that case emit about 21.4 times more SO 4 3 equivalents. Since the long shipments also are included in the case with equally much primary as secondary aluminium, although calculated with less cargo, the new produced subframe still has about 12.4 more SO 4 3 equivalents than the renewed. With 100% secondary aluminium in the new production the emissions do not differ too much from the remanufactured, when the long shipments are avoided the emissions decrease to a relatively low level. The profiling process emits a portion of NO x, this is reason why the new produced subframe has a higher amount of emitted SO 4 3 equivalents, about three times as much. 36