Glass or plastic? Study profiles changing consumer attitudes

Is glass a better alternative for food and beverage packaging than PET? That is the focus of a new study from IHS Markit (London). As plastic has become more widely used for food and beverage products over the past few decades, it has provided some benefits that glass does not. However, with consumer perception of plastic changing in a negative way, glass is beginning to challenge plastic as a material of choice.

PET packaging has several advantages over glass, which has contributed to its popularity, noted the IHS Markit case study. PET packaging is generally much lighter than glass, reducing the cost of packaging and the CO2 footprint of transporting products. Raw material costs and the cost of production processes for PET are also lower than glass on a per unit basis, giving it a further cost advantage, said IHS Markit. 

PET can also be combined with other plastics in packaging materials to give it different properties and, in some cases, lower the overall packaging weight. Plastic as a packaging material continues to be preferred over glass, accounting for 26% of the world’s plastic output, according to IHS Markit. The alcoholic beverage sector remains the one niche where glass remains king. “Glass offers lower permeability to O2 and CO2 than plastic, which means alcohol can be stored longer,” said the case study. In the soft drinks sector, this is less of an issue. With the obvious cost advantage, PET has become the dominant packaging material in that sector.

Consumer awareness of plastics in the environment may affect the use of plastic in packaging, and the case study asks if this will impact the demand for plastic packaging. 

Recycling issues that the comparison study examined were not conclusive as to which material is better. “It is difficult to directly compare the environmental impact of PET versus glass,” said the report. “Studies often fail to capture the effect of the full life cycle of a product on the environment—especially what happens to packaging at the end of its life cycle.”

The study also noted that “life-cycle assessments” often fail to account for the “real life, practical issues of waste disposal and recycling—such as waste collection infrastructure and waste sorting—leaving much of the world’s plastic waste in landfill or oceans.” 

The study finds that PET is one primary source of plastic waste that finds its way into the environment, noting that in 2017 total global demand for PET was 21.5 million metric tons (MT), of which 75 to 80% was used to make PET bottles. Around 7.3 million MT of all the PET production is recycled. “Currently all recycled PET comes from PET bottles; 6 million MT of this recycled material goes into other plastic streams, with only 1.3 million MT going into making new plastic bottles,” the study found.  

One advantage of glass, the study points out, is that it can be recycled infinitely without any loss of quality. “Therefore, glass recycling has a much more direct impact on demand for new packaging material,” said IHS Markit. “According to FEVE, the European Container Glass Federation, the use of one ton of cullet or recycled glass reduces CO2 generation by 580 kg in the glass industry, and it saves 1.2 tons of virgin raw materials.” The conclusion is that glass is more suitable for recycling than PET, as even the collection infrastructure is “much more developed” compared to that of plastic collection.

In some developing countries glass containers are returned to retail shops where the product was purchased, which then sends the bottles back to bottlers for washing and refilling. That is much like what the soft drink industry did back in the 1950s and 1960s, when consumers were paid a nickel for each returned bottle.

PET is not infinitely recyclable/reusable, “at least in the public’s perception,” said the study.  

Generally, the properties that make plastic durable and desirable for the applications in which it is used will deplete with recycling and reprocessing, which is why virgin resin is typically added to recycled material. That means the demand for virgin raw material would be higher, thus reducing the absolute benefit of recycling.

Public perception of plastics for packaging continues to erode with each news story detailing plastic bits found in fish and shellfish, and various species of birds and turtles found with plastic in their guts. Looking at recent surveys by the market research group Mintel, IHS Markit found that “79% of consumers in the UK think that plastic recycling should be incentivized, suggesting that a vast majority of consumers are concerned about plastic waste.”

Other surveys evaluated by IHS Markit, such as the one done by FEVE, “found that 85% of respondents preferred glass as a packaging material and that 73% thought it was a safer material for drink packaging.”

As the IHS Markit case study noted in its conclusion, plastic waste is “a much more visible issue,” which means that consumers are constantly aware of plastic waste in the environment. The response has been bans on certain plastic items such as retail bags, straws, stirrers and cutlery, such as the EU is planning, with “the aim of ensuring that 55% of all plastics are recycled by 2030.” 

It appears from the IHS Markit case study that consumers pay more attention to the issue of plastic waste in the environment when evaluating packaging than the true environmental impact of the overall life cycle of materials, including the obvious—and not so obvious—benefits of plastic over glass.  

Breakage issues were not studied in this comparison of glass and plastic, nor was the food waste that breakage causes. But it is obvious that one of the big advantages of plastic food and beverage packaging is the protection plastic provides from product loss, thus reducing the overall cost of food and beverages in plastic packaging to the consumer. 

Plastic also allows for drinks to be taken to swimming pools and beaches, where broken glass containers are considered a real hazard. The use of plastic containers has all but eliminated that problem.

As we all know, however, there is no such thing as a final solution to anything, as one solution often creates several more problems. The issues surrounding plastic need various solutions, but banning plastics throws out the benefits of plastic packaging. And it does not address the more thorny issues of recycling, reusing and what to do about people who do not care about the environment enough to dispose of any waste material—glass or plastic—in a proper manner.