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Metal
Cans made from steel or aluminum are the most common metal packaging and are used for a wide array of products, the bulk for food and beverages. A smaller amount of aerosol cans are used for non-food applications, such as cosmetics, body-care products, insecticides, and lubricants. Related metal packaging includes trays and foils (typically for food applications and based on rolled aluminum), closures, and lids. Almost all cans are designed as a single-use product that can be collected, shredded, remelted, and converted directly back into packaging or other uses. In considering cans on a case-by-case basis as a potential substitute for plastic packaging, brands and packagers should consider a number of key factors and issues in their decision-making process.
The following are used for general information and illustrative purposes and do not reflect a preference of or an endorsement by The Recycling Partnership or our affiliates or vendors.
- Packaging weight: Metal containers may be heavier than plastic in a range of applications, which should be taken into account when assessing costs and environmental performance impacts.
Technical and practical recyclability: Metals are commonly understood to be infinitely recyclable with little to no degradation of the metal in the recycling process. As with all materials, some material loss occurs during recycling collection and processing. Cans tend to be sorted automatically in MRF processing using eddy-current and magnetic applications.
Recycling system status: Aluminum and steel cans are almost universally collected in residential recycling programs in the U.S. and rely principally on domestic recycling markets. Aluminum has particularly high value in the recycling stream (19). Aluminum cans fall under deposit systems in 10 states, but specific product coverage varies among the states. As of 2018, the U.S. EPA reports a national recycling rate for aluminum cans of 50.4% and steel cans of 70.9% (13). Some industry analysis suggests that the steel can recycling rate is not as high as EPA data suggest (18).
Recycled content: Cans are capable of accommodating high levels of recycled content. Packages from different suppliers may have vastly different recycled content, which can have substantial implications for relative GHG emissions related to metal use.
Reusability: Metal may be suitable to be made into a reusable, multi-use packaging due to its durability. This use case is covered in the reuse models section.
Other factors: Some cans have linings that prevent metal corrosion and help maintain product quality and flavor. The need for or use of can linings and any related implications should be explored when considering cans as a plastic substitute.
Switching to metal may come with higher costs than plastic, driven both by the fact that metal is more expensive to produce per metric ton and because metal containers can be heavier than plastic. There are indications that the price point for an aluminum drink can, for example, is approximately 30% more expensive than a PET bottle (12), but more detailed case-by-case analysis should be done when considering substitutions. Switching from a lightweight flexible package to a heavy steel item may come with an even larger cost increase, but this can only be determined by interaction with packaging suppliers for specific applications and by considering all cost elements.
Primary aluminum and steel require significant energy to mine and produce, which can mean generally high greenhouse gas emissions for the virgin source materials of metal packaging. The production phase of metal emissions due to the high heat that is required to transform the ore into usable metal (3). The energy and greenhouse impact of cans decreases in relation to their recycling status – the higher the recycling rate and the higher the recycled content of cans, the lower the energy and GHG impacts of virgin metal mining and production in cans. Use phases, including energy impacts from distribution and refrigeration, should also be considered (20). LCA-based information can provide insights into relative impact more broadly (21, 22).
- High closed-loop recycling potential: Steel cans have one of the highest rates of packaging recycling at a reported 70.9% in 2018, although some industry sources suggest this figure could be lower (13, 18). The total recycling rate of all aluminum packaging was 34.9% in 2018; however, the specific rate for beer and soft drink containers was 50.4% (13). The International Aluminum Institute estimates that 75% of aluminum ever produced is still in use today (11).
High recycled-content potential : Steel food cans have recycled content up to 35% with current technology (11). An average aluminum can in the U.S. is made of 73% recycled content (14). Aluminum has a theoretical recycled content limit around 90% (3).
Long-life food storage: The fact that many canned foods do not require refrigeration before opening reduces relative environmental impacts for food storage. Commercially canned food retains quality and taste from two to five years, all without a cold chain, yielding significant energy savings. Canned food uses 20% less energy than refrigerated food and 51% less energy than frozen food (11). Canned food also maintains its high quality over time without any preservatives. The high heat process and airtight seal lock in the product’s quality while locking out germs, air, light, and other elements that degrade product quality.
Recycling value and circularity: Some industry studies provide data that the relatively high market value of cans provides vital revenue to the recycling system, offering better financial support than other materials (11). In addition, an industry analysis of aluminum cans shows high rates of potential circularity (11).
- Source recycled and/or low carbon metals: The environmental footprint of a ton of aluminum or steel varies significantly depending on its level of recycled content and the process used to manufacture it. Food can production with recycled steel can result in 75% less GHG emissions than making food cans with virgin steel (11). Aluminum production is a high-energy process and low-carbon producers draw heavily on renewable energy sources and invest to optimize their systems. Buyers of metals are increasingly demanding recycled and/or low carbon metals, which drives positive changes throughout the supply chain.
Monitor recycling rates: The environmental performance of a metal can is highly dependent on whether it is recycled after use, helping to prevent more virgin metal production. Bauxite and iron ore mining for primary metals has well-documented and extensive negative environmental impacts. Users of metals should therefore monitor actual recycling rates through EPA and other industry data (13). Similarly, understanding the acceptability in recycling programs and the actual recycling rate of the package format is critical to leveraging the benefits of metals.
Monitor virgin metal suppliers’ sourcing standards: Using virgin metal content can have impacts on GHG emissions, biodiversity, and other impact areas through its mining and processing phases. Since some primary aluminum is still required in packaging production, aluminum producers should engage with their upstream suppliers to ensure proper standards are being met in minimizing the impacts of bauxite mining. The metals industry has developed guidelines and certifications to minimize these impacts (5, 16).
Avoid material additions such as labels: Shrink-wrapped labels and other types of pressure-sensitive stickers used on metal packaging, especially cans, can have detrimental impacts on the recycling system (17).
- Improving recovery and recycling: Recycled steel and aluminum have a high potential to displace primary production, as long as the collection infrastructure and systems are in place to provide a reliable supply of secondary materials that meet the specifications. Due to the predominantly commingled-stream nature of the U.S. recycling system, materials tend to be interdependent. For that reason, an effective recovery system for all materials is an essential ingredient for the success of all packaging materials. An estimated 45 billion aluminum cans end up in landfills each year in the U.S. alone, representing an estimated $800 million worth of material that is being lost (6). Investment in collection and processing infrastructure, supporting policies, and better education and infrastructure are needed to improve the fate of end-of-life steel and aluminum (and all materials in the recycling system).
Increasing recycled-content levels to address environmental impacts: The collection, sorting, cleaning, and recycling processes require a fraction of the environmental costs associated with producing virgin aluminum (3). The relative energy savings from recycling aluminum far exceed those from recycling paper, glass, and most other materials in the waste stream (4). Seeking or requiring the highest feasible recycled content in cans is an important way to reduce potential environmental impacts from a substitution decision.
Reduction in primary metal content: To maximize the potential for aluminum as a fully circular packaging material, total primary aluminum demand must decrease with increased recycling rates. This requires coordination across the aluminum value chain to expand the recovery of high-value secondary materials that can ultimately reduce primary aluminum production. The complete removal of primary aluminum from the system is technically possible if manufacturers can create a uni-alloy (not practical from a material weight and production cost perspective) or adjust the alloy composition using aluminum scrap with the right alloy properties to reach a 100% recycled-content aluminum can. However, there are economic and supply challenges to overcome (3). The resolution of these issues could have a dramatic effect on environmental impacts.
Impacts from deposit systems: Deposit recovery schemes apply to a varying range of aluminum-packaged products in the U.S. and substantially boost overall aluminum can recovery. Whether or not a can is subject to deposit is consequential to its chance of being recycled in the U.S. and, by extension, to the relative environmental impacts of the package (23).
Return schemes: Metal cans have the potential to be used in reusable packaging systems. Companies are encouraged to conduct additional research to understand the system conditions needed to drive return schemes.
References and further reading
(1) Defining a Closed-Loop U.S. Aluminum Can Supply Chain Through Technical Design and Supply Chain Innovation (2013). (Link)
(2) Aluminium Leader. Aluminium Packaging. (Link)
(3) Metabolic (2020). RECYCLING UNPACKED. Assessing the Circular Potential of Beverage Containers in the United States. (Link)
(4) Container Recycling Institute (2002). Trashed Cans Report. (Link)
(5) Aluminium Stewardship Initiative Standards. (Link)
(6) GreenBiz (2019). The aluminum can: America’s most successful recycling story that you’ve never heard. (Link)
(7) Recycling Magazine (2016). New sorting system for separating aluminium alloys. (Link)
(8) Can Manufacturers Institute. Innovation in Food Cans. (Link)
(9) ILSI Europe (2007). 7. Metal Packaging for Foodstuffs (Link)
(10) Eva Pongrácz (2007). The Environmental Impacts of Packaging. (Link)
(11) Can Manufacturers Institute. Sustainability Advantages of Cans. (Link)
(12) Citi GPS (2018). “Rethinking single-use plastics”. (Link)
(13) EPA (2018). Advancing Sustainable Materials Management: Facts and Figures Report (Link)
(14) The Aluminium Association (2019). The Aluminum Can Advantage Key Sustainability Performance Indicators (Link)
(16) Responsible Steel (Link)
(17) ASTRX (2019). ASTRX Review of Material Flow at MRFs and Reprocessors (Link)
(18) An analysis by The Recycling Partnership shows that residential steel can recycling rates can be a low as 25%
(19) Aluminum Association (Link)
(20) Aluminum Association (2016). Analysis of the Energy and Greenhouse Gas Emission Implications of Distributing and Refrigerating Beverages (Link)
(21) PE Americas (for the Aluminum Association) – Life Cycle Impacts of Aluminum Beverage Cans May 2010 and 2014 Update. (Link)
(22) FAL (2011), “Cradle-to-Gate Life Cycle Inventory of Nine Plastic Resins and Two Polyurethane Precursors. Revised Final Report.” Prepared for the Plastics Division of The American Chemistry Council Prairie Village, KS: Franklin Associates, Ltd. (Link)
(23) Ball Corporation and Eunomia Real Circularity: The First State-b-State Assessment of Recycling Rates. (Link)
