Circular Economy Circular Economy

Plastics’ Effect on Waste:
The Answer Might Surprise You

The latest plastic product to come under fire is plastic straws. Before that, it was bags; and before that, foam foodservice items. Have you ever stopped to ask, why do we use so much plastic, especially plastic packaging? The answer depends on the type of packaging, but one of the overriding answers is that plastic is more resource efficient than its competing materials. In other words, it takes less energy (a key resource) to do the job.

By Tony Kingsbury | Published 6 years ago | About a 5 minute read

I remember as a kid getting potato chips in a box, with a bag inside, and getting deodorant in a steel spray can. Now I get both in just plastic. We used to get our milk exclusively in glass and our motor oil in a steel and paperboard canister. Now we get milk in plastic or plastic-coated paperboard and motor oil in plastic bottles. All of this plastic means a whole lot of waste. Some of it we recycle and most of it we don’t. Regardless of the waste we create, we could all do a better job of recycling. But with all of the plastic we now use, are we creating more waste?

If you are like most people, you missed the publication in the journal, Waste Management, of a peer-reviewed article entitled, “Role of plastics in decoupling municipal solid waste and economic growth in the U.S.” This article by researchers from City College of New York’s Chemical Engineering Department explored the historic drivers of municipal solid waste (MSW) and the links to the materials that make up the waste. Typically, we would expect that waste would track with population and economic growth. As the economy grows, people buy more goods and services, which economists express as personal consumption expenditure (PCE). This takes population growth out of the picture, which seems fair. As we buy more, you would expect we would throw more away. The US EPA tracks all of this MSW by material and categories, and determines what we recycle, incinerate for energy and landfill.

It turns out that as plastic grew as a material of choice, the percentage of waste that is paper, metals and glass was reduced. Since many of these other materials are recycled at a higher current rate than plastics, you might think this is bad. But in fact, the researchers determined there would be 30 percent more waste if we didn’t have plastic:

"The correlation with PCE demonstrates that since the late 1990s, there has been a decoupling of MSW generation rates with PCE or economic growth. Plastics play a role in the decoupling due to materials substitution that reduce the overall weight of MSW and down-gauging that reduces the amount of material needed."

This may seem sort of boring — admittedly, it is — but it is also important. As we consider banning plastic materials, we need to think about what we replace it with. Replacing commonly used plastic items with heavier, more resource-inefficient materials will cause an increase in energy use that correlates to greenhouse gases and climate change.

As the article states:

“To put the plastic substitution into an environmental context, information reported by Franklin et al. on six categories … determined a significant reduction in energy demand and global warming potential. The six categories are (1) caps & closures, (2) beverage containers, (3) stretch & shrink, (4) carrier bags, (5) other flexible and (6) other rigid. Thus, for example, beverage containers that normally would be glass were replaced with plastic and caps & closures that would be metal were replaced with plastic. The environmental impact in the US, where the total material weight replaced was 49.6 million kg (109 million pounds) over the six categories, resulted in an 80 percent reduced energy demand and a 130 percent reduced global warming potential impact.”

This same Franklin study also notes that while replacement reduces weight and resource use, plastics continue to be source reduced after they replace other materials such as metals or glass. Between 2000 and 2014, they averaged a 3 percent per year reduction in weight.

Another way to look at this is to consider the consequences of shifting back to non-plastic materials. A 2016 Trucost study estimated that moving away from plastics, back to historic alternatives in consumer products and packaging would increase environmental costs by 3.8 times (from $139 billion to a total of $533 billion).

My conclusions from this decoupling paper and the Trucost study are that when we can stop using something altogether, that is great. For example, if I don’t need a straw, I won’t take one. If I do need one, I need to make sure it is disposed of properly. If I need the function that a plastic item performs — such as to hold my salad or a drink — I need to think long and hard about what other materials would be used if I moved away from plastics. Besides creating 30 percent more waste, will more energy be required to make and process it and thus contribute more to global warming?

Sitting here now in burning California, the literal hotbed of climate change, I vote to manage my plastic waste properly.