Carbon Footprint Calculation

This section provides a detailed explanation of how the carbon footprint (CF) is calculated specifically for the manufacturing phase of materials.

For the manufacturing of metallic materials, Total Materia utilizes its proprietary composition data combined with ecoinvent's Life Cycle Inventory Assessment (LCIA) datasets for elements, with a focus on composition-based weighting in the calculations. For non-metallic materials, producer-specific data is prioritized over polymer family average calculations, ensuring a more accurate representation.

Metallic materials

The formula below outlines the specific calculations performed by the algorithm to derive the carbon footprint of the manufacturing of material.

Description of the elements of the formula is available below:

• – carbon footprint value of the base element obtained from Ecoinvent
• – share of alloying element obtained from Horizon
• – carbon footprint value of the alloying element obtained from Ecoinvent (it is considered only if the element is above the defined threshold for the selected material group)
• – country normalization factor – relative factor that accounts for the emission performance of the selected country compared to a reference country. This factor is calculated for each material group using data sourced from relevant articles, ensuring that variations in emissions due to geographic differences are accurately reflected in the analysis.
• – manufacturing route normalization factor. This factor is calculated for each material group using data sourced from relevant articles. Click here to see available manufacturing routes and their description.
• – scrap content adjustment – linear interpolation based on emissions data from the literature for a selected manufacturing route as a function of scrap content
• – scrap content
• – linear coefficient for specified manufacturing route

Chemical composition data in the calculation

The chemical composition data utilized in the calculations originate from material specifications that populate the Horizon database. These specifications are drawn from a variety of references, including standards from Standard Development Organizations (SDOs), scientific articles, handbooks, and other authoritative sources.

Typically, material compositions are presented as ranges or specified with minimum and maximum values. For carbon footprint calculations, a single representative value is needed. A patented method (US20090076739A1), initially developed for the identification of metal alloys, is applied to convert these ranges or minimum and maximum values into a single value. This approach leverages statistical analysis, taking into account the distribution of chemical composition values for each element within a material group.

The following elements are neglected in the calculation: hydrogen, oxygen, and nitrogen.

Threshold of alloying elements - For each group of metals, a different set of threshold values is assigned to alloying elements. They are obtained by using metallurgical expertise and have sounded physical meaning. The threshold parameter indicates at which level the element is considered in calculations; elements with value below threshold are treated as impurities and neglected in the calculation.

Description of utilized Ecoinvent datasets

Carbon footprint values for both base and alloying elements are sourced from Ecoinvent's LCIA (Life Cycle Impact Assessment) datasets. These datasets are normalized and weighted in accordance with the ISO 14000 standards methodology, helping to ensure consistency and comparability of results across various studies and applications.

• System model: Allocation cut-off by Classification

• Geography: Global - representing the average global production

• Dataset type: Market

• LCIA method: IPCC 2021 no LT

• Indicator: Climate change – Global Warming Potential 100 years (GWP100)

System model

The system model “Allocation, cut-off by classification,” or the cut-off system model, is based on the recycled content, or cut-off, approach. In this system model, wastes are the producer’s responsibility (“polluter pays”), and there is an incentivization to use recyclable products, that are available burden free (cut-off).

Geography

Global dataset is created to cover the average global production. Ideally, this global dataset is created individually to accurately reflect the global average conditions based on international data. In cases where data on the average global production are not available, the global dataset is created as the weighted average (by production volume) of several local datasets, or it is extrapolated as a copy of a local dataset. The uncertainty information in such extrapolated datasets is adjusted accordingly.

Dataset type

A market dataset collects all activities with the same reference product in a certain geographical region. Furthermore, it includes the average transport of that product within the geography, as well as inputs of the product itself to cover losses in trade and transport. In other words, they are consumption mixes of a certain product in a certain geographical region. There are either global or local markets, depending on real-life conditions and the availability of local transforming activities for specific products.

A market activity represents the consumption mix of a product for a given region, accounting for the trade between the producer and consumer, and, when needed, for product losses that occur during the product’s transportation. A market dataset does not transform a product but rather simply transfers it from one transforming activity to another.

In the attributional system models (i.e., the cut-off system model and the APOS system model), markets represent the average consumption mix of the selected product in the relevant region(s). In the consequential system model, a market represents the marginal consumption mix; it is therefore supplied by unconstrained activities with an up-to-date technology level.

Market activities account for the average transport distances and modalities of the product from producer to consumer. Transport information is set by the data provider; when information is not available, default transport assumptions are used.

LCIA method

The IPCC is the Intergovernmental Panel on Climate Change by the United Nations. The panel regularly releases Assessment Reports (ARs) containing emissions metrics for Global Warming Potential (GWP) and Global Temperature Change Potential (GTP). These numbers are implemented as the IPCC method.

What does "no LT" mean?

In a nutshell: LT stands for long-term and classifies emissions, usually from landfills, which are released into the air or leach into the groundwater more than 100 years after the landfilling happened. "no LT" means without long-term emissions.

Indicator

GWP100 is a metric used to compare the global warming impact of different greenhouse gases over a century. It quantifies how much heat a greenhouse gas traps in the atmosphere compared to carbon dioxide (CO2), which has a GWP of 1. For instance, methane (CH4) has a GWP100 of around 25, meaning it contributes 25 times more to global warming than CO2 over 100 years. GWP100 provides a standardized way to assess and compare the long-term effects of various gases on climate change, helping policymakers and businesses make informed decisions about emissions reduction.

Ecoinvent datasets used for metallic materials calculation:

– market for aluminium, primary, ingot

– market for antimony

– market for barium oxide

– market for beryllium

– market for borax, anhydrous, powder

– market for cadmium

– market for calcium carbonate, precipitated

– market for cast iron

– market for cerium oxide

– market for chromium

– market for cobalt

– market for copper, anode

– market for copper, cathode

– market for dysprosium oxide

– market for erbium oxide

– market for europium oxide

– market for ferrochromium, high-carbon, 55% Cr

– market for ferrochromium, high-carbon, 68% Cr

– market for ferromanganese, high-coal, 74.5% Mn

– market for ferronickel

– market for ferroniobium, 66% Nb

– market for gadolinium oxide

– market for gallium, semiconductor-grade

– market for gold

– market for gold-silver, ingot

– market for holmium oxide

– market for indium

– market for lanthanum oxide

– market for lead

– market for lithium

– market for lutetium oxide

– market for magnesium

– market for manganese

– market for mercury

– market for molybdenum

– market for neodymium oxide

– market for nickel, class 1

– market for palladium

– market for phosphorus, white, liquid

– market for pig iron

– market for platinum

– market for praseodymium oxide

– market for rare earth oxide concentrate, 50% REO

– market for rhodium

– market for samarium oxide

– market for scandium oxide

– market for selenium

– market for silicon, metallurgical grade

– market for silver

– market for sodium

– market for strontium carbonate

– market for sulfur

– market for tantalum powder, capacitor-grade

– market for tellurium, semiconductor-grade

– market for terbium oxide

– market for thulium oxide

– market for tin

– market for titanium, triple-melt

– market for titanium

– market for tungsten concentrate

– market for uranium ore, as U

– market for ytterbium oxide

– market for yttrium oxide

– market for zinc

– market for zirconium oxide

Ecoinvent update policy and integration in Greenline

Ecoinvent continuously updates its database to capture the latest advancements in industrial processes, technology, and global supply chains, ensuring the data remains both relevant and precise. These updates are regularly integrated in Green Line, allowing for the most up-to-date carbon footprint calculations for selected materials. This ensures that the analysis reflects current industry standards and provides accurate insights into material emissions.

Other references in Greenline - Articles

Data from selected and validated scientific articles is used to significantly broaden the scope of carbon footprint calculations. These valuable sources provide critical information, enabling more comprehensive assessments, particularly in regions or processes where Ecoinvent data is limited or unavailable. This allows for the inclusion of a wider range of countries and manufacturing methods, improved precision in definition of key parameters such as scrap content in material production, and enhanced calculations of environmental impacts for different manufacturing routes across various regions.

Steel

1. Carbon Footprint and Energy Transformation Analysis of Steel Produced via a Direct Reduction Plant with an Integrated Electric Melting Unit / J. Suer, F. Ahrenhold, M. Traverso / Springer / 2022 / Journal of Sustainable Metallurgy, 8(2022), pp.1532-1545. Available at: https://doi.org/10.1007/s40831-022-00585-x

2. Steel’s recyclability: demonstrating the benefits of recycling steel to achieve a circular economy / C. Broadbent / Springer / 2016 / The International Journal of Life Cycle Assessment, 21(2016), pp.1658-1665. Available at: https://link.springer.com/article/10.1007/s11367-016-1081-1

3. Influence of direct reduced iron on the energy balance of the electric arc furnace in steel industry / M. Kirschen, K. Badr, H. Pfeifer / Elsevier / 2011 / Energy, 36(2011), pp.6146-6155. Available at: https://doi.org/10.1016/j.energy.2011.07.050

4. Steel Climate Impact: An International Benchmarking of Energy and CO2 Intensities / A. Hasanbeigi / 2022 / Available at: https://www.globalefficiencyintel.com

5. Best Available Techniques (BAT) Reference Document for Iron and Steel Production / R. Remus, M. A. Aguado Monsonet, S. Roudier, L. Delgado Sancho / Joint Research Centre of the European Commission / 2013 / Available at: http://eippcb.jrc.ec.europa.eu

Aluminum

1. Aluminum Production in the Times of Climate Change: The Global Challenge to Reduce the Carbon Footprint and Prevent Carbon Leakage / G. Saevarsdottir, H. Kvande, B. J. Welch / Springer / 2020 / JOM (The Journal of The Minerals, Metals & Materials Society), 72(2020), pp. 296-308. Available at: https://link.springer.com/article/10.1007/s11837-019-03918-6

2. Environmental impact analysis of primary aluminium production at country level / D. Paraskevas, K. Kellens, A. Van de Voorde, W. Dewulf, J.R. Duflou / 2016 / Procedia CIRP, 40 (2016), pp.209-213. Available at: https://doi.org/10.1016/j.procir.2016.01.104

3. Aluminum Carbon Footprint: Increased Recycling Reduces Carbon Impact / Available at: https://www.aluminum.org/

4. Life-Cycle inventory data for aluminium production and transformation processes in Europe / 2018 / Available at: https://european-aluminium.eu/

Copper

1. A Review of the Carbon Footprint of Cu and Zn Production from Primary and Secondary Sources / A. E. Nilsson, M. M. Aragonés, F. A. Torralvo, V. Dunon, H. Angel, K. Komnitsas, K. Willquist / MDPI / 2017 / Minerals 7(2017)168. pp.1-12. Available at: https://doi.org/10.3390/min7090168

2. Assessing the future environmental impacts of copper production in China: Implications of the energy transition / D. Dong, L. van Oers, A. Tukker, E. van der Voet / Elsevier / 2020 / Journal of Cleaner Production, 274 (2020) 122825. Available at: https://doi.org/10.1016/j.jclepro.2020.122825

3. Copper Environmental Profile / 2023 / Available at: https://copperalliance.org/

Zinc

1. A Review of the Carbon Footprint of Cu and Zn Production from Primary and Secondary Sources / A. E. Nilsson, M. M. Aragonés, F. A. Torralvo, V. Dunon, H. Angel, K. Komnitsas, K. Willquist / MDPI / 2017 / Minerals 7(2017)168. pp.1-12. Available at: https://doi.org/10.3390/min7090168

Available manufacturing routes for selected metallic materials

Steel

The manufacturing routes for steel available in the Green Line module include several key processes, each with distinct characteristics and environmental impacts:

1. Blast Furnace-Basic Oxygen Furnace (BF-BOF): This is one of the most widely used methods for steel production. The process begins with the blast furnace, where iron ore, coke, and limestone are heated to produce molten iron. The molten iron is then transferred to the basic oxygen furnace, where it is mixed with scrap steel and oxygen to reduce carbon content, resulting in the production of steel. While this method is efficient for large-scale production, it is energy-intensive and associated with significant CO2 emissions due to the reliance on coal-derived coke as a fuel source.

2. Electric Arc Furnace (EAF): This process is primarily used for recycling scrap steel. In an electric arc furnace, high-voltage electric arcs are used to melt scrap steel, which is then refined into new steel. EAF is considered more energy-efficient and environmentally friendly compared to BF-BOF, as it uses significantly less energy and does not require iron ore. Since it heavily relies on recycled materials, its carbon footprint is generally lower, especially when renewable energy is used to power the furnace.

3. Direct Reduced Iron-Electric Arc Furnace (DRI-EAF): In this route, iron ore is first reduced to direct reduced iron (DRI) using a reducing gas (typically natural gas or hydrogen) rather than coke. The resulting DRI is then melted in an electric arc furnace to produce steel. This method is more energy-efficient than BF-BOF and produces fewer carbon emissions. When hydrogen is used as the reducing gas, the DRI-EAF process can be nearly carbon-free, making it an increasingly attractive option for green steel production.

4. Undefined (Country Average): This represents the average steel production route for a given country. It combines data from various manufacturing methods used within that country, providing a general overview of steel production's environmental impact. This option allows for an average calculation when specific production routes are not defined, offering a useful approximation for carbon footprint assessments based on regional manufacturing practices.

Aluminum

For aluminum, the Green Line module includes the Conventional Manufacturing Process, which refers to the traditional method of producing aluminum from bauxite ore. This process involves two main steps:

1. Bayer Process: Bauxite ore is first refined to produce alumina (aluminum oxide) through the Bayer process. This involves crushing the bauxite and using a chemical process to extract alumina, which is a highly energy-intensive stage due to the required heat and chemical reactions.

2. Hall-Héroult Process: The alumina is then subjected to electrolysis in the Hall-Héroult process, where it is dissolved in molten cryolite and subjected to an electric current to produce pure aluminum metal. This step is extremely energy-dependent, typically powered by electricity, which significantly influences the carbon footprint. When renewable energy sources are used, the environmental impact is greatly reduced, but the conventional process often relies on non-renewable energy.

This conventional method of aluminum production is energy-intensive and contributes significantly to CO2 emissions, primarily from the electricity required in electrolysis. However, efficiency improvements and the use of renewable energy can reduce its carbon footprint.

Copper

For copper, the Green Line module includes the following manufacturing processes:

1. Pyrometallurgy: This is the most common method for copper production and involves extracting copper from its ores through high-temperature processes. The main steps include smelting, converting, and refining. Copper ore is first heated in a furnace to produce copper matte, which contains copper and iron sulfides. This matte is then processed to remove the sulfur and iron, leaving behind blister copper, which is refined further to obtain pure copper. Pyrometallurgy is energy-intensive and generates significant CO2 emissions due to the reliance on fossil fuels for heating.

2. Hydrometallurgy: This process is used for lower-grade copper ores and involves leaching the copper from the ore using an acidic solution. The copper is then recovered from the solution through a series of chemical reactions, including solvent extraction and electrowinning (SX-EW). Hydrometallurgy is less energy-intensive compared to pyrometallurgy, but it typically takes longer and is used in specific contexts, such as for oxide ores or tailings. While this method generally produces fewer emissions, the environmental impact varies depending on the chemicals and energy sources used in the process.

3. Undefined (Country Average): This represents the average copper production method for a particular country. It combines data from various processes, such as pyrometallurgy and hydrometallurgy, to provide a generalized overview of copper production's environmental impact within that region. This option is useful for assessing the carbon footprint when the specific production route is not defined, offering an approximation based on regional manufacturing practices.

Zinc

For zinc, the Green Line module includes the following manufacturing processes:

1. Pyrometallurgy: This process involves extracting zinc from its ores through high-temperature smelting. Zinc ores, typically sulfides, are roasted to produce zinc oxide, which is then reduced to metallic zinc in a furnace. The pyrometallurgical process is energy-intensive, using heat generated from fossil fuels, which contributes to significant CO2 emissions. This method is often employed for zinc production on a large scale, but it has a higher environmental impact due to the energy required for smelting.

2. Hydrometallurgy: This process is a lower-temperature method for extracting zinc, typically from oxidized ores. The zinc is leached from the ore using sulfuric acid, creating a zinc sulfate solution. Through a series of steps, including purification and electrolysis, metallic zinc is obtained. Hydrometallurgy is less energy-intensive compared to pyrometallurgy and often produces fewer emissions, making it a more environmentally friendly option depending on the energy sources used.

3. Electrometallurgy: This specific type of hydrometallurgical process uses electrolysis to extract zinc from the zinc sulfate solution. Zinc is deposited onto cathodes in an electrolytic cell, producing high-purity zinc. Electrometallurgy is commonly used for large-scale zinc production and is more efficient in terms of energy use when compared to pyrometallurgy. However, the environmental impact depends on the electricity source, with renewable energy greatly reducing the carbon footprint of this process.

4. Undefined (Country Average): This option provides an average calculation for zinc production in a given country, combining data from pyrometallurgical, hydrometallurgical, and electrometallurgical methods. It offers a generalized view of zinc manufacturing's environmental impact in that region, which is helpful when specific production routes are not defined. This country average serves as an approximation for carbon footprint assessments based on regional manufacturing practices.

Non-metallic materials

For non-metallic materials, carbon footprint calculations are approached differently due to the nature of the available data. When specific producer data is available, it takes precedence, offering the most accurate reflection of the material's environmental impact based on real-world production conditions. This producer-specific information can include details such as energy consumption, production processes, or regional factors that directly influence emissions. By prioritizing this data over broader industry averages, the calculation can more accurately represent the material’s actual carbon footprint.

However, in many cases, non-metallic materials, such as polymers, do not have fully disclosed chemical compositions. This lack of transparency makes it impossible to base the carbon footprint calculation on precise chemical data. As a result, the system utilizes average data for the material's broader classification. While this approach may not capture the exact emissions profile of a specific product, it provides a reasonable and standardized estimate based on industry-wide trends. This method ensures that even in the absence of detailed composition data, the carbon footprint calculation remains robust, allowing for reliable assessments across a wide range of non-metallic materials.

All references utilized for carbon footprint calculations are meticulously documented and listed at the bottom of the Carbon Footprint page. This comprehensive documentation ensures that users have easy access to the sources of data and methodologies employed in the calculations, promoting transparency and credibility in the analysis. The accompanying screenshot illustrates this feature, highlighting the clear organization of references that supports the accuracy of the carbon footprint assessments.

The data sourced from producers is clearly indicated on the website, with a dedicated label "Producer data" in the Manufacturing column of the table. This labeling allows users to easily identify which data points are derived directly from manufacturers, ensuring transparency and confidence in the accuracy of the information presented. By highlighting producer-specific data, the system facilitates informed decision-making regarding the carbon footprint of non-metallic materials, making it straightforward for users to differentiate between producer data and broader averages. Below is a screenshot illustrating this feature.

Ecoinvent datasets used for non-metallic materials calculation:

– market for acrylonitrile-butadiene-styrene copolymer

– market for epoxy resin, liquid

– market for ethylene vinyl acetate copolymer

– market for glass fibre reinforced plastic, polyamide, injection moulded

– market for latex

– market for nylon 6

– market for nylon 6, glass-filled

– market for nylon 6-6

– market for nylon 6-6, glass-filled

– market for phenolic resin

– market for polybutadiene

– market for polycarbonate

– market for polydimethylsiloxane

– market for polyester resin, unsaturated

– market for polyethylene terephthalate, granulate, amorphous

– market for polyethylene, high density, granulate

– market for polyethylene, linear low density, granulate

– market for polyethylene, low density, granulate

– market for polylactic acid, granulate

– market for polymethyl methacrylate

– market for polyphenylene sulfide

– market for polypropylene, granulate

– market for polystyrene scrap, post-consumer

– market for polystyrene, general purpose

– market for polystyrene, high impact

– market for polysulfone

– market for polyurethane adhesive

– market for polyurethane, flexible foam

– market for polyurethane, flexible foam, flame retardant

– market for polyurethane, rigid foam

– market for polyvinyl chloride, unspecified polymerisation, weighted average

– market for polyvinylfluoride

– market for polyvinylidenchloride, granulate

– market for styrene-acrylonitrile copolymer

– market for synthetic rubber

– market for urea formaldehyde resin

– market for cement mortar

– market for cement, CEM II/A-L

– market for cement, CEM II/A-S

– market for cement, CEM II/A-V

– market for cement, CEM II/B-L

– market for cement, CEM II/B-S

– market for cement, CEM II/B-V

– market for cement, CEM III/A

– market for cement, CEM III/B

– market for cement, CEM III/C

– market for cement, CEM IV/A

– market for cement, CEM IV/B

– market for cement, CEM V/A

– market for cement, CEM V/B

– market for cement, Portland

– market for cement, Portland Slag

– market for cement, Pozzolana Portland

– market for cement, unspecified