Reusable plastic takeout containers score significantly better on greenhouse gas emissions, energy and water use than single-use plastic cartons—so long as you use them more than a dozen times, and don’t put them in the dishwasher, a new study finds.
It might seem like a no-brainer that reusable plastics are more environmentally sound than single-use, which lock us into a constant cycle of producing new plastic from fossil fuels. But actually, when you drill down into the lifecycle of a reusable container, it’s not always that simple, the researchers on the new study point out.
For instance, reusable containers—which are being trialed by some restaurants in buy-and-return takeout schemes to reduce their plastic footprint—are typically made of heavier and thicker plastic, which require more resources to manufacture. These containers also require regular washing to enable reuse, as well as transport costs involved in ferrying them back and forth between restaurants and consumers’ homes. These additional factors, compounded over the lifetime of a single container, can increase its footprint.
Can the benefits of reusable containers be balanced with the costs of their production and use? That was the focus of the Resources, Conservation & Recycling study.
As its focus, it chose a Michigan-based pilot program that’s trialing the use of reusable takeout containers between restaurants and customers. The researchers looked at three types of reusable containers, made of polypropylene and silicon, and compared them with three conventional single-use containers, and one further container made out of bagasse, a biodegradable sugarcane pulp.
Then they applied a life cycle analysis to these products, covering everything from the emissions, energy and water required for the production of each, to the impact of their end-of-life disposal.
They also took a close look at how these products were used over their lifetimes—especially relevant for the reusable containers. This factored in the electricity costs of cleaning a reusable carton in a dishwasher, compared to hand-rinsing with cold water; they even looked at detergent use. They also incorporated the transport costs of consumers taking special (described as ‘excess’) trips to drop off a container—i.e. when customers travel simply to return packaging rather than to collect a new order.
This intensive analysis revealed that while reusable plastic containers do have a higher initial production footprint compared to single-use, crucially, these costs diminish over time.
In fact over multiple uses, the global warming potential and energy costs are offset, compared to single-use plastic. The time this took varied by plastic type. But overall, “the study found that the reusable alternatives can break even with single-use containers after four to 13 uses: 4 to 6 for GHG emissions and 8 to 13 for primary energy [use],” says Gregory Keoleian, director of the Center for Sustainable Systems at the University of Michigan, and lead author on the paper.
Beyond this point, reusable containers made environmental gains—showing a better track record than single-use on all metrics. Over the course of 20 uses, the primary energy footprint of reusable containers decreases by 54-67%, and their global warming potential by 71-80-% compared to single-use containers. What’s more, widespread reusable containers would reduce solid waste by 81% compared to a continued system based on single-use.
But this comes with caveats, because these gains are highly sensitive to the impact of consumer behavior, the research found.
“One of our key findings was that the benefits of the reusable container system can be quickly reversed If customers make special trips by automobile to return reusable containers without picking up new orders,” Keoleian says. Even if just 5% of customers make unnecessary car trips, those energy savings quickly decline—eclipsed by the fuel costs. The study also modeled what would happen if, say, 100% of customers cleaned their reusable containers in the dishwasher—a factor that would increase their global warming potential by 120%, compared to a scenario where everybody rinses them instead.
These discoveries hold practical insights for the restaurant industry, whose large contribution to plastic waste also gives it outsized potential to reduce it. It’s clear also that we need to up the rate of reuse rather than relying on recycling alone, which only happens globally at a rate of 9%. The study suggests that reusable cartons could make a tangible difference against this backdrop—but it depends on enhancing certain consumer behaviors.
For instance, restaurants who engage in return schemes might want to educate consumers on the benefits of hand-rinsing their containers before returns. Perhaps they could provide drop-off points to reduce the journey time for consumers returning plastic tubs, or incentivize consumers’ non-car returns: “Of course, visiting your local restaurant by bicycle, walking, or public transit is the best way to pick up your takeout and return containers,” Keoleian said.
Meanwhile, making sturdy but more lightweight containers and manufacturing them from recycled plastics, will crucially also reduce the reliance on fossil fuels.
The takeaway? Both industry and consumer changes matter in the battle against plastic pollution—but we really need to know how to make those count.
Keoleian, et. al. “Parametric life cycle assessment modeling of reusable and single-use restaurant food container systems.” Resources, Conservation & Recycling. 2023
Updated: Monday 30 January 2023 at 13:00 MST.