An analysis of different types of packaging over their life-time suggests that plastics can provide the lowest carbon dioxide emissions of available materials, provided it is recycled properly, according to researchers at Imperial College London (London / UK). In a study titled “Examining Material Evidence – The Carbon Fingerprint” and commissioned by waste management group Veolia (Paris / France; www.veolia.com), the researchers analysed more than 70 life-cycle assessments (LCAs) to determine the environmental impacts of packaging materials, including impacts from mining, manufacturing, logistics, usage and end-of-life management covering recycling or disposal. The study concludes “that plastic can provide the lowest carbon emissions of available materials providing it is recycled properly, effectively debunking the growing movement to switch away from plastic in all scenarios.”

Only 2% of British people consider plastics, compared to other materials used in packaging, to contribute the least greenhouse gases to the environment from its production, use and post-use treatment. But looking at the numbers, plastics are the least impactful, says the report. “Plastics do have a large carbon impact – accounting for 3.8% of global greenhouse gases emissions – but it is wrong to assume that alternative packaging materials would perform better, and it is important to consider the carbon benefits that arise from plastics use,” it says.

When considering the production and manufacturing of the main alternatives to plastics for a 500 ml bottle, other packaging types (fibre, glass, steel and aluminium) result in the emission of more greenhouse gases than plastic bottles, with glass bottles being the highest emitter overall. The researchers explain, for example, that if all plastic bottles used globally were made from glass instead, the additional CO₂ emissions would be equivalent to powering about 22 large coal-fired power plants. This is equivalent to the electricity consumed by a third of the UK.

However, there are cases where the converse is true, for example local supply chains for milk can mean that glass milk bottles make sense in terms of CO₂ emissions, the report says. “Therefore, every case must be assessed in its own merits, since there will be examples of liquid fibre board, metals and glass presenting better packaging solutions on a carbon basis,” it adds.

Nick Voulvoulis, professor of environmental technology at Imperial College, says, “We need to reduce plastics production while ensuring that any alternatives do not contribute more to climate change. The findings of this study demonstrate that removing, reducing, reusing or recycling the plastic packaging placed on the market is an important part of the way forward, and a better option to replacing it with current alternative materials, or waiting and hoping for solutions not yet available.”

Undertaking LCAs to compare the environmental performance of alternative materials for different packaging applications is essential if we want to take into account the environmental impacts associated with the whole life-cycle of packaging, the researchers say.

The key to limiting environmental impact and CO₂ emissions is the reduction, reuse, optimisation of recycled content and effective waste management to treat packaging at its end of life, and recycling always wins over virgin production on all environmental indicators, says the report. For plastics, it has been shown that recycling saves between 30% and 80% of the carbon dioxide emissions that virgin plastics processing and manufacturing generate. If all polymers were recycled this could result in mean annual savings of 30m-150m t of CO₂, equivalent to shutting between 8-40 coal-fired power plants globally. With the widespread application of renewable energy and demand-management strategies, increasing the recycling of plastics has the potential to both curb the growing life-cycle greenhouse gas emissions from plastics and prevent them from entering the marine environment, the report adds.