The cost of plastic packaging
The changes have happened so gradually that most consumers havent even noticed, but a tremendous amount of plastics have crept onto supermarket shelves. Shoppers are tossing a lot of plastic packages into their carts that didnt exist when they were kids. Cucumbers sleeved in polyethylene film are now ubiquitous in the produce department, as are sliced fruits in polyethylene terephthalate (PET) containers and chopped, ready-to-eat salads in polypropylene bags. People dont have to make their own guacamole or hummus anymoreit comes already prepared in convenient polypropylene tubs. Resealable plastic pouches, made from sophisticated multilayered films, are all over the supermarket. Shoppers can spot them on dry goods shelves containing granola, brown sugar, and beef jerky. They hang in refrigerator cases displaying shredded cheeses and cold cuts and are stacked in freezers filled with chicken, fish sticks, and french fries. Even tuna is starting to come in easy-to-open metallised pouches instead of the familiar stout can. Vacuum-packed steak, ribs, and chicken are a growing presence in meat department cases. Environmental activists say the material is causing the planet huge environmental damage and that the chemical industry should do more to make packaging easier to recycle. Industry acknowledges a need to improve but says it is combating an even bigger environmental challenge, food waste. Chemical & Engineering News looks at this contentious debate, including ways in which the two sides are edging closer together. Many industry critics think all these plastics are a bit much. Its so immensely curious how stupid modern packaging is, William McDonough, a designer and sustainability guru, told a greenbiz.com reporter a few years back. To McDonough and like-minded critics, flexible plastics, especially the newer multilayered films, are another excess of a throwaway society. They are much harder to recycle than the simpler metal, paper, and glass containers they replace. Too many of the new materials end up in landfills or bobbing around the ocean. And they make it all too easy for people to simply discard things without a thought to the damage they are doing to the planet. The packaging industry, though, doesnt think its products are so stupid. It sees plastics as a solution to another big environmental problem: food waste. Flexible plastics dont shatter or dent, and if they are well-engineered, they dont rip or puncture either. Their multilayered structures ensure long-term preservation of the food inside. And they are lighter and cheaper to transport than metals or glass. Plastic packaging today is so much more than a shopping bag or wrapping, says Cindy Shulman, vice president of packaging and resins for ExxonMobil Chemical. It really is about preservation and protection of food and getting it to people. At the same time, the industry cant help but acknowledge the negative consequences of plastic waste. Companies are responding by making plastics thinner, saving on materials and environmental impact. Theyre also beginning to make packages simpler and thus easier to recycle. With such steps, they hope to head off a serious backlash. Consumers enjoy the convenience of plastic packaging even if they dont realise the amount of engineering that goes into the multilayered structures. There isnt that awareness, even in the packaging industry, says Jeff Wooster, global sustainability director for Dow Chemicals packaging and specialty plastics unit. If you talk to someone whose expertise is designing corrugated containers, they might not understand why we use more than one plastic to make a package. But all those polymers in packaging film are there for their own special reasons. The workhorse is polyethylene, explains Susan Selke, director of Michigan State Universitys School of Packaging. As a general rule, if polyolefins will do the job, then they will be the least expensive, she says. Polyethylene gives the package its bulk and structural integrity. If more toughness is needed, a packaging company might opt for PET, the resin of choice for beverage containers. Polyethylene can also be used to seal the package. But often lower-melting-point ethylene-vinyl acetate is the better choice for that. And if the food inside the package is greasy, a food company might opt for a higher-end sealant such as DuPonts Surlyn. Most food packages need a barrier layer to protect against oxygen. Ethylene-vinyl alcohol (EVOH) is popular because it is more effective in blocking oxygen than polyethylene, PET, or nylon. If even more barrier is needed, a package might incorporate metallised film, Selke says. To explain what flexible packaging brings to the food industry, experts often point to two examples: cucumbers and meat. Shoppers may wonder what the heck plastic is doing on cucumbers, which did fine on their own for many years. But the polyethylene shrink wrap protects the surface of the cucumber and helps it retain moisture. According to the Flexible Packaging Association (FPA), the film extends the shelf life of a cucumber from three days to 14. The steaks that consumers buy in the supermarket are usually packaged by the stores own meat department in polystyrene foam trays and a film such as polyvinyl chloride. Distributed this way, FPA says, steaks generally last four days. If the meat is processed centrally and vacuum-packed in a multilayer film that includes an EVOH barrier, it can last for nearly a month. Environmental advocates acknowledge the benefits that multilayer packages bring. Unlike other contentious products of the plastic industry, such as plastic bags and polystyrene foam, they arent being targeted for outright bans. But environmental activists argue that the industry should do something about the packaging waste that is mounting in the environment. Everyone acknowledges that multilayer flexible containers are more difficult to recycle than simpler packages like aluminium cans or PET bottles. The layers cant be separated, so they are shredded and re-extruded into plastic pellets together. Often they are relegated to lower value uses such as plastic lumber for park benches rather than new packages. Activists think of such downgrading, called cascaded recycling, as a last resort. In January, the Ellen MacArthur Foundation released a report that quickly became influential. The New Plastics Economy: Rethinking the Future of Plastics attempts to reconcile industry and activists on the packaging issue. The report was the product of input from environmental groups like Ocean Conservancy as well as companies important to packaging such as Dow, the consumer products company Unilever, and the packaging firm Amcor. The New Plastics Economy details the scale of the packaging waste problem. In 2013, industry produced 78 million metric tons of plastic packaging worldwide. Of that, 40% was landfilled and another 32% was leaked to the environment, polluting land and sea. Only 28% of the plastic, the report says, was collected for further use. Half of that was incinerated for energy. The other half was recycled. After processing losses and cascaded recycling, just 2% of the original 78 million metric tons was recycled into the high-value applications it originated from. Between the small amount of plastics collection and the lower value uses, only 5% of the packagings original value was retained. Losses to the economy because of the current system run as high as $120 billion per year. You have this highly engineered package that is used for maybe a few weeks, and then it sits for hundreds of years at a landfill, says Conrad MacKerron, senior vice president of the corporate responsibility group, As You Sow, who was a consultant for the Ellen MacArthur Foundation report. Whether you are an environmental advocate or not, it is a waste of materials that have significant value. Thats not good business. These economic losses arent the only problems with plastic waste cited by the report. It points to the estimated 150 million metric tons of plastics currently residing in the worlds oceans. Packaging accounts for more than 60% of the plastics recovered in coastal clean-up operations. Without significant action, there may be more plastic than fish in the ocean, by weight, by 2050, the report says. The environmental costs of packaging add up. Trucost, a consulting group that tabulates the environmental impact of business practices in dollar terms, conducted a study on behalf of the United Nations Environment Programme in 2014. Its report, Valuing Plastic: The Business Case for Measuring, Managing and Disclosing Plastic Use in the Consumer Goods Industry, looked at costs such as disposal and greenhouse gas emissions. The report found the environmental cost of using all plastics to be $75 billion annually. The food and soft drinks sectors were the biggest contributors, accounting for 23% and 12% of the overall impact, respectively. The cost of plastic packaging is high, but the cost of not using it may be higher. Ask any packaging industry official about sustainability, and food waste will come up quickly. Indeed, the food waste issue is connected to some staggering statistics of its own. The world wastes a third of the food it produces, 1.3 billion metric tons per year, according to the Food & Agriculture Organization of the UN. In the U.S. alone, $165 billion is spent producing food that goes to waste, says the Natural Resources Defense Council, an environmental group. Manufacturing the wasted food accounts for 25% of U.S. freshwater use and 4% of U.S. oil consumption. An oft-cited industry rule of thumb is that packaging represents only 10% of the energy required to make and deliver food to the consumer. This figure is from an Industry Council for Packaging and the Environment report that includes nonplastic packaging such as the cardboard boxes used to transport food. Any reduction of that 10% cant come at the expense of the other 90%, plastics advocates point out. The most important thing we can do for sustainability is protect the food inside, Dows Wooster says. Improved food protection through better packaging can yield real environmental benefits. The Austrian consulting group Denkstatt looked at steak packaged in a vacuum skin instead of the traditional combination of foam tray and film. Food waste declined from 34% to 18%, resulting in a 2,100-g CO2-equivalent greenhouse gas reduction per steak. In a recent study, Trucost took this example further and found a $606 decrease in environmental costs per metric ton of steak. Generally, pricey foods such as meat reap a bigger benefit from packaging because they are more resource-intensive to produce than bulk goods such as rice. Dows Wooster sees that in the supermarket. The meat and cheeses on display around the perimeter of the store tend to have higher-tech packaging than the goods in the interior, where glass bottles, metal cans, and paper sacks still flourish. The companies that deliver meat to the market are generally willing to invest in the packaging that extends the shelf life, he says. As You Sows MacKerron gets the arguments, but he suspects the industry has gone too far with all the plastics. It really raises questions in my mind whether we are looking at overpackaging in some cases, he says. Why must food last two years when six to eight months might do just fine? he asks. David Clark, vice president of safety, environment, and sustainability at Amcor, says such instances are rare. Our customers aim at delivering the most value to consumers, he says. They are not going to look for excessive packaging or to try to overpackage anything. Amcor has a database of 4,885 life-cycle assessments (LCAs) of packaging. Most of them, he says, justify the use of plastics. Even packaging that may seem over-the-top to the layperson can stand up under closer scrutiny. Take K-Cup-style single-serve coffee capsules. The LCA firm Quantis Canada conducted a study for the PAC Packaging Consortium, an industry group, comparing their impact to that of drip-brewed coffee. It found that under the best-case scenario, where drip-brewed coffee wasnt wasted, the two come out even. And because the capsules offer portion control, they come out ahead when dumping old coffee from the pot is considered. Amcor is also in the business of paper and aluminium packaging and for many years made glass bottles and aluminium cans, Clark points out. When compared side by side with these materials for packaging applications, he says, plastics usually come out ahead. Earlier this year, Trucost followed the report it conducted for the UN with one commissioned by the American Chemistry Council, a trade association. One of the questions was whether it would help reduce environmental costs if we switched away from using plastic, says Libby Bernick, senior vice president at Trucost. In fact, it wouldnt help at this point, given the environmental costs of the alternative materials. It would make things worse. The company compared plastics with a basket of materials such as aluminium, paper, and glass. It found that the environmental impact of the alternatives was better than plastics per kilogram. However, in most applications, much less plastic is needed. In food packaging, for example, 4.6 times the amount of alternative materials is required to do the same job as plastics. Such comparisons dont absolve the industry, As You Sows MacKerron points out. If consumer brands are putting disruptive materials onto the market, they need to somehow pay for or take responsibility for post-consumer collection and recycling, he says. I dont think you can just say, Your LCA says it has fewer greenhouse gases so its okay. Industry ownership of the problem is a big part of the New Plastics Economy report. The emphasis is on a circular economy, in which the industry cultivates a supply chain for used materials so they will be reusedideally in their original, high-value applications. The report calls on industry to simplify the materials it uses in multilayer packaging. It suggests a search for a superpolymer with the functionality of todays polymers and with superior recyclability. Combining toughness, flexibility, barrier properties, and other attributes into a single polymer is probably a long way off, but the industry is trying to simplify packages to facilitate recycling. Dow, for instance, has developed a stand-up pouch made entirely of polyethylene. The package, Dows Wooster acknowledges, doesnt have great barrier properties. But it does have one food application, Tyson frozen chicken sold in Mexico, and its being rolled out for a big nonfood use: Seventh Generation dishwasher pods. Bernard Rioux, who heads global marketing for DuPonts packaging resins business, says a single superpolymer may be unnecessary because different kinds of polyolefins can be recycled together. Meat packaging can be purely polyolefin based, he says. Rioux adds that one good step in the direction of single-polymer packaging would be getting rid of the metallized layers needed for high-barrier packaging. Amcors AmLite technology is precisely along these lines. It involves applying a micrometre-thick silicon oxide layer to a polyolefin film. The silicon oxide has a lower carbon footprint than aluminium and performs just as well, Amcors Clark says. It is essentially like a thin layer of glass on the inside of the plastic. Juice pouches and other flexible packages made with the AmLite technology can have a 40% smaller carbon footprint than conventional metallised pouches, according to Clark. Similar technology is already used in plastic wine bottles, where it reduces the weight of the bottles by up to 90% and allows for 30% more wine to be loaded onto each truck. In rigid applications, Clark claims, the technology has also proven to be more compatible with recycling than polymer barriers. Applications such as this that use less material are the plastics industrys go-to strategy for minimising cost and environmental impact. According to Trucost, if the industry could reduce materials consumption in food and beverage applications by 30%, $7.3 billion in environmental costs could be avoided. To do that, chemical companies will have to come up with materials that can do the same job with less. This is one of the reasons tougher, metallocene-catalysed polyethylene has been gaining in popularity. According to ExxonMobils Shulman, one classic failure that occurs in plastic packages, such as large sacks for rice, are pinholes that come from the stress of shipping. With newer high-performance polyethylenes such as ExxonMobils Exceed XP, you no longer get those holes, she says. That same quality, Shulman says, allows companies to downgauge a product such as the shrink wrap for beverage six-packs by about 50%. Compared with a cardboard carton, she adds, such a wrap delivers a 70% reduction in greenhouse gas emissions. DuPonts Rioux says the industry is reaching the limit in terms of how much traditional downgauging it can do. He advocates another emerging approach to making films thinner, called coextruded biorientation. Biaxial orientationstretching polymer films to align their polymer chainsis not new. Biaxially oriented polypropylene is used in most potato chip bags. But it hasnt been used on multilayered film until now. The trick, Rioux says, is keeping the polymers in the amorphous state during the melt phase to prevent crystallisation. You have to control 50 different parameters to make it work. But it works, he says. Premium plastics made with coextruded biorientation might not be the superpolymers the New Plastics Economy report had in mind, but they do help ease the environmental burdens of plastics. Industry and its critics may disagree on a lot, but no one can argue with charging good money for a plastic that will only be used in small amounts.
Chemical & Engineering News, 17 October 2016 ;http://pubs.acs.org/cen/news ;