In Part II, we discussed the refining and manufacturing processes that make plastic production carbon intensive and toxic. This week, we'll be looking at where plastic goes after use.You finish your yoghurt. As you rinse out the container, you notice the chasing arrows symbol embossed on the bottom surrounding a 5. Below it is PP for polypropylene. Then you toss the container into your recycling bin, which you will park next to the curb on your pickup day. It’s been recycled, right? Not really. How much will it add to greenhouse gas emissions? That depends on how it is managed.
According to the United Nations Environment Program, global plastic waste adds up to nearly 300 million tons annually. That’s about the weight of the entire human race. There’s no comprehensive data on the composition of that waste. We do know that in 2015, approximately 28 percent of it was unmanaged (more on unmanaged plastic to come in Part IV). As for managed plastic, some 40 percent consisted of packaging materials, mostly single-use, while the remaining 60 percent comprised non-packaging materials.
Data about emissions from plastic waste management practices are also sketchy. Currently, the best estimates pertain to packaging materials.
Emissions from Plastic in Landfill and from Recycling Plastic Are Low
Managed plastic waste is handled in one of three ways: buried in landfill, incorporated into new products, or incinerated, the most carbon-intensive of the three methods.
In 2015, some 31 percent of global plastic packaging (75 percent in the US) ended up in landfill, the management method that results in the lowest emissions. Landfilled plastic does not emit greenhouse gases. Emissions from plastic come mostly from transporting it in CO2 -emitting trucks from the place where it’s recycled to the SMART station to landfill.That’s not to say that plastic in landfill doesn’t harm the environment. Nearly every piece of plastic ever created still exists. A water bottle takes 450 years to decompose, and a disposable diaper, 500. When they do break down, they leach toxic chemicals, which end up in groundwater. Meanwhile, organic matter in landfill accounts for about 12 percent of global methane emissions.
In 2015, another 20 percent of global plastic packaging was recycled. Recycling rates vary enormously from place to place: in the US, they hover around 9 percent while Europe recycles about 30 percent of its plastic thanks in part to extended producer responsibility laws. In the developing world, practically 0 percent is recycled.
Not all plastic waste is recyclable. Straws are not. Black plastic is not. Mixed plastics are usually not. Whether or not a given managed plastic item is recycled depends on local recycling technology, the type of plastic, the item’s composition, and market demand and price for that type of plastic. If nobody can make money from the item (and often no one can), it will not be recycled. In fact, only no. 1 and no. 2 plastics are regularly recycled. That no. 5 yoghurt container? In all likelihood, it will wind up in a landfill or incinerator.
What’s more, recycling plastic isn’t the same as recycling, say, glass. Glass can be endlessly transformed into new products; plastic cannot. Plastic consists of chains of polymers (identical molecular units bonded together). When a plastic product is recycled,
some of the chains break down, which means that virgin plastic must be added to upgrade its quality. Emissions from recycling plastic include those from extracting fossil fuel to manufacturing and transporting the virgin plastic added to the plastic that’s being reused. All the same, a product made from recycled plastic is much better from a climate perspective than a product made from 100 percent virgin plastic.
Unfortunately, a piece of plastic can be recycled only two or three times before it degrades to the point where it’s unusable. Then it too goes to landfill or the incinerator.
Incineration Drives Emissions from Managed Plastic
In 2015, an additional 20 percent of plastic packaging waste was incinerated under managed conditions. Not only does burning plastic require fossil fuel to heat the incinerators, but also it pumps major greenhouse gases into the atmosphere. Emissions from incinerating managed plastic packaging waste in 2015 amounted to 16 million metric tons of CO2 equivalents, including 6 million metric tons from the US. The climate impact of burning plastic waste in the US alone equaled that of driving 1.26 million passenger vehicles.
The steam from burning plastic can be used to generate power, and industry is pushing to expand plastic incineration (known as Waste-to-Energy) as a source of renewable energy. In fact, 23 states classify it as such. Yet given the amount of carbon emitted in extracting and manufacturing the plastic, burning plastic for power has a bigger lifecycle carbon footprint than generating power from natural gas combustion. Burning one metric ton of plastic produces nearly one ton of CO2 emissions. It also releases toxic pollutants like dioxins and heavy metals that must be treated as hazardous waste.
Future technologies may mitigate this problem. Gasification and pyrolysis are hailed by the plastics industry as a means of dealing with that portion of single-use plastic that cannot realistically be phased out. But those technologies are rejected as “high risk, low yield” by the Global Alliance for Incinerator Alternatives. Meanwhile, a group of British scientists is working to develop plastics made from waste CO2 that would pull greenhouse gases from the atmosphere.
Currently, plastics-related emissions total half a percent of global emissions at 190 million metric tons. However, if the petrochemical industry expands as projected, GAIA estimates that annual greenhouse gas emissions from managed plastic packaging (totaling about one-quarter of all plastic waste) will skyrocket to 309 million metric tons. The Center for International Environmental Law foresees emissions from plastic production and incineration totaling 56 billion tons between now and 2050. That’s almost fifty times the annual emissions of all US coal power plants. A University of California research team projects that by 2050 emissions from plastics will add up to 17 percent of the global carbon budget —the amount of greenhouse gases we can emit while keeping global temperatures from rising more than 1.5 degrees Celsius.
Research Is Underway About the Climate Impact of Unmanaged Plastic Packaging
The least understood part of the plastics equation is unmanaged plastic. How big is the climate impact of the 28 percent of global plastic packaging that is not dutifully placed in a recycling bin, wheeled to the curb, and handled by experts? That’s openly burned? That chokes drainage systems, piles up in vacant lots, and swims in the ocean? Stay tuned for Part IV to learn more.
Coming Next — Part IV: Emissions from Plastic in the Environment
Want to join in the effort to stop the plastics catastrophe? Learn more about 350 Silicon Valley’s work to regulate plastics and/or join our team. Email plastics@350siliconvalley.org.