A Clearer Path to Sustainability

How advancements in PET technology help reduce life-cycle costs

By Tracee Reeves, Chief General Counsel for Graham Packaging

Ever since its invention more than 100 years ago, plastic has literally helped shape our world. Plastic packaging has become a ubiquitous part of society – being both revered and vilified for its convenience. Single-use plastics have been criticized for contributing to both ocean and landfill waste. However, plastics are proving to be less harmful to the environment than previously thought.

One example is polyethylene terephthalate or PET. This plastic resin was first synthesized in North America by DuPont chemists during the 1940s. Labeled with the No. 1 resin identification code on or near the bottom of bottles and containers, PET is predominantly used to package a range of products, including beverages, shelf staples, bakery goods, produce, frozen foods, cosmetics and household cleaners. Prized for its strength, thermostability and transparency, PET is a popular choice for packaging.

Concerns over global warming via carbon emissions and greenhouse gases are forcing the packaging industry to focus beyond first cost and consider the total cost of ownership (TCO) of its bottles and containers. Companies with a strong investment in the future of plastic packaging are conducting life-cycle assessments (LCA) to provide customers and consumers with a complete “cradle-to-grave” analysis of its impact on the environment.

What is a Life-cycle Assessment?

LCA is a quantitative, science-based method that rigorously evaluates the environmental impact of a product across its entire life cycle. The focus on multiple environmental impact categories provides a holistic view that can be used to identify and implement improvement opportunities for reducing the environmental footprint. There are several areas of consideration when conducting an LCA:

  • Global warming potential, or carbon footprint, is the amount of greenhouse gases released during the production and use of a product – which can have a significant impact on climate change.
  • Energy use or energy footprint is the amount of direct or indirect energy consumed across the entire life cycle of a product. Saving energy uses less fossil fuel while reducing air pollution and greenhouse gas emissions.
  • Acidification is the damage to ecosystems caused by acid rain, nutrient runoff and other man-made pollutants. Plant growth and animal health can be affected by acidification.
  • Particulate matter is a mixture of small particles like dust, smoke and fumes that are present in air pollution. Health problems such as damaged lungs and impaired breathing are linked to air particulates.
  • Smog is a mixture of air pollutants made up mostly of ground-level ozone. It results from a chemical reaction between sunlight and air pollution from vehicles, factories and power plants. It can cause respiratory infections as well as impaired lung function.

The power of LCA provides an objective, science-based perspective needed to understand the benefits and trade-offs of material choices in packaging applications. These insights allow manufacturers to make a clear, informed choice about existing material applications as well as the technologies that can be developed to make packaging materials even more sustainable.

Environmental Impact of Glass vs. Plastic

A recent LCA study was conducted to compare the environmental impact of glass jars versus PET plastic jars. A sample of 1,000 jars was studied throughout the life cycle and included:

  • Jars, caps and packaging materials;
  • Transportation to filling locations;
  • Hot filling and pasteurization;
  • Packaging;
  • Transportation to grocery stores; and
  • Disposal of unrecycled jars in landfills.

The results of the study found that PET jars have lower life-cycle impacts than glass jars in the following categories: global warming potential (38 percent less), energy use (16 percent less), acidification (55 percent less), particulate matter (93 percent less) and smog (55 percent less). Raw material and manufacturing impacts per jar are lower for PET than glass jars – consuming 14 percent less energy and releasing 54 percent less greenhouse gas emissions.

What factors contribute to PET having a lower footprint? First, PET jars release fewer emissions over their life cycle due to more efficient manufacturing techniques and less material used. The reduction in material usage and the lighter weight of PET jars also require less energy to make, fill, package, transport and recycle or landfill than glass jars.

Finally, because of their lighter weight, 40 percent more PET jars can be put on each truck for transport, requiring fewer shipments and less fuel during transport to recycling or end-of-life disposal. Since they are virtually shatterproof, they need less packaging during transport than glass containers.

Taking PET Into New Markets With Upgraded Thermal Performance

Certain foods and beverages are thermally processed at very high temperatures and pressures which, historically, PET has not been able to withstand. However, new technological advancements in Graham’s blow molding process alter the molecular orientation of the PET resin, driving greatly enhanced performance into the blown container. These new jars have thermal stability above 300 F and 50 percent greater sidewall rigidity than standard PET.

Another performance benefit during the hot-filling or retort process is the ability for the thin-walled containers to be heated up and cooled down quickly, without the risk of thermal shock and breakage that glass has. This is especially beneficial for food and beverage products because it minimizes the total amount of time the product is exposed to elevated temperatures, thus optimizing both flavor and nutrition profiles.

The container also delivers a two-year shelf life at ambient temperatures thanks in part to a nano-thin gas barrier layer of silicon oxide applied to the interior of the container after it is blown. Best of all, this barrier layer does not prevent the PET containers from being 100 percent recyclable. This new PET technology is also shatter-resistant, which translates into less breakage and downtime during filling operations and transportation.

Eliminating Barriers to Recyclability

Companies are embracing the circular economy – which aims to minimize waste while maximizing resources – by exploring new technologies to reduce or eliminate barriers to recyclability, chemically recycled plastics and bio-based plastics.

Energy use is a key driver for greenhouse gas emissions and other environmental and health impacts. PET uses less energy across its life cycle, which reduces a variety of environmental impacts. Less PET is also used, compared to the weight and volume of other materials required to fulfill the same function.

Many factors affect the environmental performance of materials. Every material choice has impacts across its life cycle. Raw materials must be mined or harvested and then transported for processing. The material properties can affect the design and function of the product and how much material is needed for the design. Some materials are more easily recycled, reused and reworked than others based on their molecular content. Reducing material consumption is a key step towards a circular economy.

Manufacturing activities involve shaping and assembly operations. The weight of the material affects its transport throughout the life cycle. Additionally, materials can have different disposal and recycling options at end of life. All of these factors combined create the product’s overall environmental footprint.

The Future of Food Packaging

Advancements in PET technology have allowed companies to enjoy the benefits of plastic with none of the drawbacks. Consumers can now see the product without the fragility of glass. PET is also inexpensive, lightweight, resealable, shatter-resistant and highly recyclable.

Graham Packaging continues to make improvements to the environmental impacts of its products and operations. As it develops new packaging concepts, processes and technologies, Graham Packaging demonstrates their sustainability and consumer benefits from the manufacturing line to the store shelf to the recycling center. This LCA study illuminates the environmental benefit of Graham Packaging’s PET compared to glass in pasta sauce jars –  another step in the journey towards a more sustainable planet.