Life Cycle Assessment of Magnesium Components in Vehicle Construction

This introduction paper is based on the paper "Life Cycle Assessment of Magnesium Components in Vehicle Construction" published by "German Aerospace Centre e.V. (DLR) for the International Magnesium Association (IMA)".

1. Overview:

• Title: Life Cycle Assessment of Magnesium Components in Vehicle Construction
• Author: Simone Ehrenberger
• Year of publication: 2013
• Journal/academic society of publication: German Aerospace Centre e.V. (DLR), Institute of Vehicle Concepts (Report for the International Magnesium Association (IMA))
• Keywords: Magnesium, Life Cycle Assessment (LCA), Vehicle Construction, Transport Applications, Lightweight Design, Pidgeon Process, Electrolysis, Die Casting, Sand Casting, End-of-Life, Recycling, Aluminium Comparison, Greenhouse Gas Emissions.

2. Abstract:

Magnesium has considerable potentials as lightweight material for many applications and offers valuable advantages in transport. Lightweight design is a key solution to increase the efficiency of road vehicles, trains, or aircrafts and lower emissions. To evaluate ecological benefits and prevent trade-offs between single life stages, the whole life cycle must be considered. This study, initiated by the International Magnesium Association (IMA), analyses the entire life cycle of magnesium components for two exemplary transport applications (vehicle and aircraft components), comparing them to aluminium. It covers primary magnesium production, alloying, component production, use phase, and end-of-life. The study aims to provide up-to-date, reliable data on energy consumption and emissions associated with magnesium, offering valuable information for producers, manufacturers, and end-users. The study follows ISO 14040 and 14044 standards for life cycle assessment and includes a critical review by an external expert.

3. Introduction:

Major global trends like scarcity of resources, climate change, and increasing demand for mobility necessitate highly efficient technical solutions. CO2 and fuel consumption specifications are severe, requiring significant improvements. Lightweight design is crucial for reducing energy consumption in transport applications. Magnesium, with its favorable characteristics in production, manufacturing, use phase, and end-of-life, offers considerable potential. While magnesium has been used in vehicles for decades, further developments are needed to enhance its broad application. Energy consumption and emissions from magnesium production are often higher than for steel and aluminium. However, magnesium offers significant weight savings (about 55% vs. steel, 25% vs. aluminium), leading to fuel and emission savings during the use stage. This study, initiated by the International Magnesium Association (IMA), assesses the life cycle of magnesium to demonstrate its environmental benefits and compare it with competitive materials like aluminium. A cradle-to-grave approach is used, considering vehicle and aircraft components, to provide real-world data and calculated results for energy consumption and emissions.

4. Summary of the study:

Background of the research topic:

The transport sector faces increasing pressure to reduce emissions and improve energy efficiency. Lightweight design is a primary strategy to achieve these goals. Magnesium, being the lightest structural metal, offers significant potential for weight reduction in vehicles and aircraft, leading to lower fuel consumption and emissions during the use phase. However, the environmental impact of magnesium production and processing must be carefully evaluated across the entire life cycle.

Status of previous research:

Previous assessments indicated that primary magnesium production, particularly the Pidgeon process, had high energy consumption and greenhouse gas emissions, often exceeding those of aluminium. However, technological advancements in production processes and a shift towards using gaseous fuels and waste heat recovery have led to significant improvements in recent years. This study provides updated data reflecting these changes.

Purpose of the study:

The study aims to:

• Assess the entire life cycle of magnesium components in automotive and aircraft applications.
• Provide up-to-date and reliable data concerning energy consumption and emissions for the production, use, and end-of-life of magnesium.
• Compare the environmental performance of magnesium components with equivalent aluminium components.
• Offer valuable information for producers, manufacturers, and end-users to support design and decision-making processes regarding the use of magnesium.
• Identify ecological benefits and potential trade-offs associated with magnesium lightweighting.

Core study:

The study is divided into four main parts:

1. Magnesium Production: Analysis of primary magnesium production via the Pidgeon process (mainly in China) and electrolysis, including recent technological developments.
2. Component Production: Evaluation of manufacturing processes for two exemplary components: a die-cast magnesium steering wheel frame for passenger cars and sand-cast magnesium door parts for aircraft.
3. Use Phase: Assessment of fuel and emission savings during the operational life of vehicles and aircraft due to weight reduction from magnesium components.
4. End-of-Life: Analysis of the recycling and disposal of magnesium components, including current practices and alternative recycling paths.
   Throughout the study, magnesium components are compared to functionally equivalent parts made from aluminium. The assessment follows ISO 14040/14044 standards.

5. Research Methodology

Research Design:

The study employs a Life Cycle Assessment (LCA) methodology, adhering to ISO 14040 and 14044 standards. The analysis is structured into four modules: primary magnesium production, magnesium-specific design and parts manufacturing, life cycle performance of magnesium in transport applications, and end-of-life and recycling.

• The analysis of magnesium production (Pidgeon process, electrolysis) is a cradle-to-gate assessment.
• Alloy and component production (die casting, sand casting) and the end-of-life stage are analyzed gate-to-gate.
• The overall life cycle of the steering wheel is evaluated from cradle-to-grave.
• For aircraft parts, the focus is on production and use phase break-even points.
  Comparisons are made with equivalent aluminium components.

Data Collection and Analysis Methods:

• Data Sources: Primary data from magnesium producers, component manufacturers, and industry experts (e.g., International Magnesium Association members, Chinese Magnesium Association) were used for core processes. Upstream processes and data gaps were filled using literature and the ecoinvent database 2.2.
• Impact Assessment: The CML 2001 method was used for impact assessment. The study focuses primarily on Global Warming Potential (GWP), expressed as kg CO2 equivalents (CO2eq) over a 100-year horizon, based on IPCC characterization factors. Other categories assessed include Acidification Potential (AP, kg SO2eq), Eutrophication Potential (EP, kg PO4eq), and Abiotic Depletion Potential (ADP, kg Sbeq).
• Software: Umberto was used for material and energy flow modeling for the Pidgeon process.

Research Topics and Scope:

• Primary Magnesium Production: Evaluation of the Pidgeon process (representing 2011 Chinese production) and electrolysis (site-specific for Israel, carnallite-based).
• Magnesium Parts Manufacturing:
  • Die casting: Magnesium steering wheel frame (AM50 alloy).
  • Sand casting: Magnesium aircraft door parts (gearbox and seal closers, AZ91E alloy).
• Alloying: Production of AM50 and AZ91E alloys.
• End-of-Life: Processing of end-of-life vehicles (ELVs), recycling of magnesium within the aluminium cycle (standard scenario), and recovery of primary magnesium (alternative scenario).
• Use Phase: Calculation of fuel savings and emission reductions for a passenger car (200,000 km mileage) and an A320 aircraft (flight distance 4,100 km).
• System Boundaries: Restricted to emissions to air for primary magnesium production, processing, and recycling, apart from upstream processes from ecoinvent.

6. Key Results:

Key Results:

• Primary Magnesium Production (2011 data):
  • Pidgeon Process (China, weighted average): 25.8 kg CO2eq / kg Mg. Crediting the use of waste coke oven/semi coke oven gas reduces this to 19.9 kg CO2eq / kg Mg. FeSi production is a dominant factor for impacts.
  • Electrolysis (Israel, natural gas-based): 17.8 kg CO2eq / kg Mg. Crediting by-products (Cl2, KCl) reduces this to 14.0 kg CO2eq / kg Mg. Electricity consumption is the main factor.
• Magnesium Parts Manufacturing:
  • Die Casting (Steering Wheel): The magnesium steering wheel generally has lower environmental impacts (e.g., GWP) compared to an aluminium part in a gate-to-gate analysis, mainly due to less material being processed. However, the use of SO2 as a cover gas leads to comparatively high acidification potential.
  • Sand Casting (Aircraft Parts): Production of magnesium parts shows lower impacts for climate change and resource depletion than aluminium parts. The production of sand moulds and the casting process itself (fluxes, energy) are significant contributors to impacts.
• End-of-Life and Recycling:
  • The standard scenario for magnesium end-of-life is its recycling within the aluminium cycle.
  • The energy consumption for ELV treatment is much lower than for aluminium alloy processing. For GWP, vehicle treatment contributes about 4% to the overall emissions of 3.8 kg CO2eq / kg material processed for recycling.
• Comparison of Magnesium vs. Aluminium Components (Life Cycle Perspective):
  • Steering Wheel (Passenger Car, 200,000 km): Magnesium components can achieve a net CO2eq emissions benefit compared to aluminium.
    • Break-even point for Pidgeon-produced Mg (coke oven gas) is around 150,000 km.
    • If waste gas use is credited for Pidgeon process, break-even is at 46,000 km.
    • Mg produced by electrolysis already shows lower production emissions than the aluminium reference.
  • Aircraft Parts (A320): Due to high fuel savings potential in aviation, the amortization of any higher production emissions for magnesium parts occurs rapidly.
    • Break-even is reached at the latest during the ninth flight for most magnesium scenarios.
    • If Mg is produced by electrolysis with by-product credits, component production already has fewer emissions than the aluminium reference.
    • Emission savings during aircraft operation amount to approximately 8 t CO2eq per year for the analyzed components.

Figure Name List:

• Figure 5: Greenhouse gas emissions of Pidgeon process
• Figure 6: Overview of magnesium life cycle for transport applications
• Figure 33: Overall balance for magnesium steering wheel compared to aluminium steering wheel based on a mileage of 200,000 km
• Figure 40: Savings of greenhouse gas emissions during use stage for different magnesium scenarios (for steering wheel)
• Figure 44: Number of flights for emission amortization for difference magnesium scenarios (for aircraft parts)

7. Conclusion:

The study concludes that the environmental performance of magnesium in transport applications has significantly improved and offers benefits compared to aluminium, particularly when considering the entire life cycle.

• Magnesium Production: The Pidgeon process shows higher CO2 emissions than electrolysis, but technical improvements have significantly reduced Pidgeon process emissions in recent years. Crediting waste gas utilization further improves its performance. Electrolytic Mg has inherent CO2 advantages, especially with renewable energy.
• Component Manufacturing: Magnesium parts generally require less material processing, leading to advantages in gate-to-gate comparisons. Cover gas type and production scrap rates are key influencing factors.
• Recycling: Recycling processes themselves do not contribute significantly to overall life cycle emissions, but crediting the reuse of magnesium (e.g., substituting primary material) has a major positive influence on the LCA.
• Passenger Car Components (Steering Wheel): Break-even points for CO2eq emissions are sensitive to the primary magnesium source and end-of-life assumptions. Magnesium produced by electrolysis can be advantageous from the production stage. For Pidgeon-produced magnesium, break-even is typically achieved within the vehicle's lifetime.
• Aircraft Components: Magnesium parts in aircraft show significant CO2 emission benefits due to high fuel reduction potential, leading to rapid amortization of any initial higher production emissions.
• General: Already with existing magnesium production technologies, it is possible to gain advantages over aluminium if components are designed specifically for magnesium characteristics. The choice of primary metal source, processing efficiencies, and end-of-life management are critical for maximizing these benefits.

8. References:

• Aghion, E. and S. C. Bartos (2008). Comparative Review of Primary Magnesium Production Technologies as Related to Global Climate Change. 65th Annual World Magnesium Conference. Warsaw, International Magnesium Association.
• Albright, D. L. and J. O. Haagensen (1997). Life cycle inventory of magnesium. IMA 54: Magnesium Trends, Toronto, Canada, International Magnesium Association.
• Ehrenberger, S. and H. Friedrich (2013). "Life-Cycle Assessment of the Recycling of Magnesium Vehicle Components." JOM 65(10): 1303-1309.
• Gao, F., Z. Nie, Z. Wang, X. Gong and T. Zuo (2009). "Life cycle assessment of primary magnesium production using the Pidgeon process in China." The International Journal of Life Cycle Assessment 14(5): 480-489.
• ISO 14040 (2006). Environmental management – Life cycle assessment – Principles and framework.
• ISO 14044 (2006). Environmental management – Life cycle assessment – Requirements and guidelines.
• Ramakrishnan, S. and P. Koltun (2004). "Global warming impact of the magnesium produced in China using the Pidgeon process." Resources, Conservation and Recycling 42(1): 49-64.

(Note: The full list of references can be found on pages 101-103 of the original paper.)

9. Copyright:

• This material is a paper by "Simone Ehrenberger". Based on "Life Cycle Assessment of Magnesium Components in Vehicle Construction".
• Source of the paper: IMA LCA Study Report (DLR). (DOI Not available in the provided document).

This material is summarized based on the above paper, and unauthorized use for commercial purposes is prohibited.
Copyright © 2025 CASTMAN. All rights reserved.