Metal and carton packaging are both commonly used for the packaging of food in Norway, such as in the packaging of crushed tomatoes. Several food retailers have shifted from metal to carton food packaging, however, knowledge in terms of considering environmental impacts and aspects of to inform such a transition have so far been limited and especially for Norwegian conditions. Several aspects are important in influencing the environmental impact of metal and carton food packaging, including methodological choices for allocation in recycling, the type of data applied and the definition of the system boundaries. Country specific factors such as the recycled content in the product, collection rates and the applied waste treatment processes also influence the environmental impact results to a large extent.
This study was commissioned by Norsk Metallgjenvinning with the goal to increase knowledge about the environmental strengths and weaknesses of metal food packaging compared with carton food packaging in a life cycle perspective under Norwegian conditions. This was done by collecting specific data for collection and recycling of the food packaging options, and by applying various methods for modelling of recycling in LCA, in addition to assessing the circularity performance of these products.
LCA, which is a standardised method to quantify the environmental impacts of a product or a service throughout its life cycle, was used to assess environmental impacts. The Material Circularity Indicator (MCI), introduced by the Ellen McArthur Foundation, was applied to assess product-level circularity. Three different methods for modelling recycling were tested: the cut off approach, end-of-life net scrap approach and the more recently developed Circular Footprint Formula (CFF) within the Product Environmental Footprint (PEF) methodology. In addition, two improvement scenarios for the metal food packaging were defined: increased share of recycled content and change in location of the manufacturing
The results show that the carton food packaging in general is associated with lower environmental impacts compared to metal food packaging from a life cycle perspective. This is true for all environmental impact categories assessed in this study, except for land use and marine eutrophication. When using the material circularity Indicator, the metal packaging obtains a better product circularity score than the carton packaging. A higher value for the circularity is preferable as it indicates a more circular product according to the MCI, which can have a value between 0 and 1, where the latter indicates a fully circular product. The higher circularity score for the metal food packaging can be described by, for example, its relatively higher recycled content.
The results are dependent on the conditions assessed in this study, and it should be noted that a lot of generic data had to be applied, e.g. for the production processes of the food packaging, due to limited data availability. Recommendations for reduced environmental impacts of the metal packaging include to use recycled steel. As production of metal is relatively energy intensive, the type of energy carrier used in the manufacturing phase also contributes significantly to the total climate change impact. The use of renewable energy sources is therefore preferred. The transport from store to consumer and the waste treatment of the distribution packaging also contributes significantly to the total climate change impact. This study shows contrasting results between circularity and environmental impacts of the food packaging. The metal food packaging is associated with a higher product-level circularity but the carton food packaging in general associated with lower environmental impacts. This indicates the complexity of this type of assessments and the importance of considering both circularity and life cycle environmental impactsin these types of studies.