Dynamics of aluminum use in the global passenger car system: Challenges and solutions of recycling and material substitution
Doctoral thesis, 2015
This thesis analyzes the relationship between the design of vehicles, end-of-life vehicle
(ELV) management, and global material production using aluminum as an example.
Vehicle manufacturing, material industries and ELV management face different
challenges. An important challenge for vehicle manufacturers is the design of
lightweight vehicles to reduce energy use and greenhouse gas (GHG) emissions in the
use phase for which an increased use of aluminum of different alloys is an attractive
option. The aluminum industry has an interest in reducing energy consumption and
GHG emissions, which can be accomplished effectively through recycling. ELV
management must be improved to enable the first two systems to use aluminum scrap in
a sustainable manner. Today, the sorting of different alloys is limited. As a result of
having mixed scrap at the ELV phase and limited opportunities for aluminum refining,
there may be a future scrap surplus that cannot be absorbed by the aluminum-recycling
sink, which is passenger cars. These three sectors are connected through material flows,
and a change in one of the sectors can severely affect the others' options for reaching
their goals.
This thesis addresses the following questions: 1) How are the dynamics of the global
vehicle stock changing the boundary condition for aluminum recycling? 2) What are the
most effective interventions to minimize a future aluminum scrap surplus? 3) What are
the options for material substitution in vehicles to reduce direct and indirect GHG
emissions over time?
To answer these questions, a system approach is employed to analyze how these three
sectors are linked and to explore options for all sectors to reach their objectives in the
long term. This thesis employs global bottom-up stock-driven models of the aluminum
cycle. A basic model was used to identify the scrap surplus problem. A refined model
with segments, components and alloys resolution combined with a source-sink diagram
was used to evaluate different solution options. In addition, a global dynamic fleetrecycling
MFA model was developed to simulate the future impacts of material
substitutions of conventional steel with high-strength steel (HSS) and aluminum on
material cycles, energy use and GHG emissions related to the global passenger vehicle
fleet.
The main findings in this thesis are: i) a continuation of the current practice of cascadic
use would eventually result in a scrap surplus because this practice depends on the
continuous and fast growth of the secondary casting stock in the global vehicle fleet, a
condition that is unlikely to be met. Model simulation indicated a non-recyclable scrap
surplus by approximately 2018±5 if no alloy sorting is introduced. The surplus is
potentially substantial and could grow to reach a level of 0.4-2 kg/cap/yr by 2050,
thereby significantly reducing the option of the aluminum industry to reduce its energy
consumption through recycling. ii) Drastic changes in ELV management practices are
necessary to make use of the growing scrap flow in the future, including further
dismantling and efficient component-to-component recycling, alloy sorting of mixed
shredded scrap, and designing recycling-friendly alloys that function as alternative sinks
for aluminum scrap. iii) Light-weighting has the potential to substantially reduce global
emissions of vehicles (9-18 gigatons cumulative CO2-eq. between 2010 and 2050). In
the medium term (5-15 years), global emissions reductions from substituting standard
steel with aluminum are similar to those achievable by HSS; however, over a longer
term (after 15-20 years), substitution with aluminum can reduce total emissions more
effectively, provided that the wrought aluminum will be recycled back into automotive
wrought aluminum.
The environmental consequences of products in general and passenger cars in particular
have led to an increasing awareness of the dependencies between the shaping of
vehicles and the shaping of the environment. Governments and intergovernmental
bodies have formulated quality goals for the environment, such as the 2-degree target,
and have introduced emissions standards, thereby extending the responsibility of
automobile manufacturers to the use phase. On the materials side, legislation has been
introduced to extend producer responsibility, mainly with the goal of avoiding toxic
substances and reducing the amount of waste, as is noted in different end-of-life vehicle
(ELV) legislation and directives. The current ELV directives do not sufficiently address
the management of material systems as a whole or quality issues related to material
recovery. To harmonize ELV management with goals for the global aluminum cycle and
its impacts for the environment, it is essential to understand how the above-mentioned
systems interact.
Has parts
Paper 1: Modaresi, Roja; Müller, Daniel B.. The Role of Automobiles for the Future of Aluminum Recycling. Environmental Science and Technology 2012 ;Volum 46.(16) s. 8587-8594 http://dx.doi.org/10.1021/es300648w Copyright © 2012 American Chemical Society
Paper 2: Rombach, Georg; Modaresi, Roja; Müller, Daniel B.. Aluminium Recycling- Raw Material Supply from a Volume and Quality Constraint System. World of Metallurgy - ERZMETALL 2012 ;Volum 65.(3) s. 157-162
Paper 3: Modaresi, Roja; Løvik, Amund Nordli; Müller, Daniel Beat. Component- and Alloy-Specific Modeling for Evaluating Aluminum Recycling Strategies for Vehicles. JOM: The Member Journal of TMS 2014 ;Volum 66.(11) s. 2262-2271., The article is not included due to copyright available at http://dx.doi.org/10.1007/s11837-014-0900-8
Paper 4: Løvik, Amund Nordli; Modaresi, Roja; Müller, Daniel Beat. Long-term strategies for increased recycling of automotive aluminum and its alloying elements. Environmental Science and Technology 2014 ;Volum 48.(8) s. 4257-4265 http://dx.doi.org/10.1021/es405604g Copyright © 2014 American Chemical Society
Paper 5: Modaresi, Roja; Pauliuk, Stefan; Løvik, Amund Nordli; Müller, Daniel Beat. Global Carbon Benefits of Material Substitution in Passenger Cars until 2050 and the Impact on the Steel and Aluminum Industries. Environmental Science and Technology 2014 ;Volum 48. s. 10776-10784 http://dx.doi.org/10.1021/es502930w Copyright © 2014 American Chemical Society
Publisher
NTNU
Series
Doctoral thesis at NTNU;2015:116
(ELV) management, and global material production using aluminum as an example.
Vehicle manufacturing, material industries and ELV management face different
challenges. An important challenge for vehicle manufacturers is the design of
lightweight vehicles to reduce energy use and greenhouse gas (GHG) emissions in the
use phase for which an increased use of aluminum of different alloys is an attractive
option. The aluminum industry has an interest in reducing energy consumption and
GHG emissions, which can be accomplished effectively through recycling. ELV
management must be improved to enable the first two systems to use aluminum scrap in
a sustainable manner. Today, the sorting of different alloys is limited. As a result of
having mixed scrap at the ELV phase and limited opportunities for aluminum refining,
there may be a future scrap surplus that cannot be absorbed by the aluminum-recycling
sink, which is passenger cars. These three sectors are connected through material flows,
and a change in one of the sectors can severely affect the others' options for reaching
their goals.
This thesis addresses the following questions: 1) How are the dynamics of the global
vehicle stock changing the boundary condition for aluminum recycling? 2) What are the
most effective interventions to minimize a future aluminum scrap surplus? 3) What are
the options for material substitution in vehicles to reduce direct and indirect GHG
emissions over time?
To answer these questions, a system approach is employed to analyze how these three
sectors are linked and to explore options for all sectors to reach their objectives in the
long term. This thesis employs global bottom-up stock-driven models of the aluminum
cycle. A basic model was used to identify the scrap surplus problem. A refined model
with segments, components and alloys resolution combined with a source-sink diagram
was used to evaluate different solution options. In addition, a global dynamic fleetrecycling
MFA model was developed to simulate the future impacts of material
substitutions of conventional steel with high-strength steel (HSS) and aluminum on
material cycles, energy use and GHG emissions related to the global passenger vehicle
fleet.
The main findings in this thesis are: i) a continuation of the current practice of cascadic
use would eventually result in a scrap surplus because this practice depends on the
continuous and fast growth of the secondary casting stock in the global vehicle fleet, a
condition that is unlikely to be met. Model simulation indicated a non-recyclable scrap
surplus by approximately 2018±5 if no alloy sorting is introduced. The surplus is
potentially substantial and could grow to reach a level of 0.4-2 kg/cap/yr by 2050,
thereby significantly reducing the option of the aluminum industry to reduce its energy
consumption through recycling. ii) Drastic changes in ELV management practices are
necessary to make use of the growing scrap flow in the future, including further
dismantling and efficient component-to-component recycling, alloy sorting of mixed
shredded scrap, and designing recycling-friendly alloys that function as alternative sinks
for aluminum scrap. iii) Light-weighting has the potential to substantially reduce global
emissions of vehicles (9-18 gigatons cumulative CO2-eq. between 2010 and 2050). In
the medium term (5-15 years), global emissions reductions from substituting standard
steel with aluminum are similar to those achievable by HSS; however, over a longer
term (after 15-20 years), substitution with aluminum can reduce total emissions more
effectively, provided that the wrought aluminum will be recycled back into automotive
wrought aluminum.
The environmental consequences of products in general and passenger cars in particular
have led to an increasing awareness of the dependencies between the shaping of
vehicles and the shaping of the environment. Governments and intergovernmental
bodies have formulated quality goals for the environment, such as the 2-degree target,
and have introduced emissions standards, thereby extending the responsibility of
automobile manufacturers to the use phase. On the materials side, legislation has been
introduced to extend producer responsibility, mainly with the goal of avoiding toxic
substances and reducing the amount of waste, as is noted in different end-of-life vehicle
(ELV) legislation and directives. The current ELV directives do not sufficiently address
the management of material systems as a whole or quality issues related to material
recovery. To harmonize ELV management with goals for the global aluminum cycle and
its impacts for the environment, it is essential to understand how the above-mentioned
systems interact.
Has parts
Paper 1: Modaresi, Roja; Müller, Daniel B.. The Role of Automobiles for the Future of Aluminum Recycling. Environmental Science and Technology 2012 ;Volum 46.(16) s. 8587-8594 http://dx.doi.org/10.1021/es300648w Copyright © 2012 American Chemical Society
Paper 2: Rombach, Georg; Modaresi, Roja; Müller, Daniel B.. Aluminium Recycling- Raw Material Supply from a Volume and Quality Constraint System. World of Metallurgy - ERZMETALL 2012 ;Volum 65.(3) s. 157-162
Paper 3: Modaresi, Roja; Løvik, Amund Nordli; Müller, Daniel Beat. Component- and Alloy-Specific Modeling for Evaluating Aluminum Recycling Strategies for Vehicles. JOM: The Member Journal of TMS 2014 ;Volum 66.(11) s. 2262-2271., The article is not included due to copyright available at http://dx.doi.org/10.1007/s11837-014-0900-8
Paper 4: Løvik, Amund Nordli; Modaresi, Roja; Müller, Daniel Beat. Long-term strategies for increased recycling of automotive aluminum and its alloying elements. Environmental Science and Technology 2014 ;Volum 48.(8) s. 4257-4265 http://dx.doi.org/10.1021/es405604g Copyright © 2014 American Chemical Society
Paper 5: Modaresi, Roja; Pauliuk, Stefan; Løvik, Amund Nordli; Müller, Daniel Beat. Global Carbon Benefits of Material Substitution in Passenger Cars until 2050 and the Impact on the Steel and Aluminum Industries. Environmental Science and Technology 2014 ;Volum 48. s. 10776-10784 http://dx.doi.org/10.1021/es502930w Copyright © 2014 American Chemical Society
Publisher
NTNU
Series
Doctoral thesis at NTNU;2015:116
Author
Roja Modaresi
Norwegian University of Science and Technology (NTNU)
Subject Categories
Other Environmental Engineering
Environmental Management
Energy Systems
Publisher
Chalmers