Glass Vs Plastic: Which Is More Recyclable & Sustainable?

In sustainable living circles, we tend to blindly accept the notion that plastic is automatically worse than just about any other material, but we really consider the full life cycle analysis (LCA), this isn’t actually always the case. Sometimes, the “eco-friendly” choice ends up having a higher impact.

So is glass more environmentally friendly than plastic?

There’s a lot to unpack(age) here so we’ll sip, snap, zip, bottle, and button our way through each material, highlighting the good, the bad and the ugly.

Given the sustainability’s movements overwhelming preference of glass, it’s easy to assume the answer to the query, “Is glass better for the environment than plastic?” would be YES.

And indeed, before it becomes a transparent jar that looks great holding all your bulk store hauls, glass starts out as a few natural raw materials: silica (sand), soda ash, limestone, and/or dolomite, along with a small number of other minerals. All materials abundantly available on Earth, right?

We’ve got an abundance of sandy beaches to turn into glass! Not so fast. Only a specific type of sand can be transformed into glass, and it’s often sourced from seabeds and river beds, disrupting natural ecosystems and stealing microorganism habitats. As the second most consumed natural resource, we’re quickly running out of sand.

Energy Use & Production Impact

In its most environmentally-friendly manner, just sand, soda ash, and limestone are melted at high heat (around 1500°C) to form a liquid that, as it cools, will become glass in its various shapes and sizes. In some cases (typically not for container glass), dolomite is used in addition to limestone in order to improve the viscosity of glass in its liquid form, which helps to make it more resistant (but can also release pollution).

Let’s back up a bit. 1500°C is HOT. Glass demands higher heat than plastic, and you can probably guess how heating anything to that high temperature is possible: fossil fuels. In the U.S. this mostly comes from natural gas, but elsewhere it might come from even more carbon-intensive sources, like petroleum or coal.

Additionally, glass manufacturing can release dangerous particles into the atmosphere and has been associated with acidification and smog formation.

Is Glass More Recyclable Than Plastic?

Glass is 100% recyclable. Better yet, it’s infinitely recyclable—meaning it can be transformed into a new product again and again without any loss in quality. Every ton of cullet (recycled glass) saves roughly 1.2 tons of raw materials from being sourced.

Unfortunately, one of glass’ biggest environmental influences (the fossil fuels required for heat) is unavoidable. A high amount of energy is still needed to melt glass down in the recycling process. Another slight drawback is the fact that about 16% of the emissions saved by processing recycled glass are offset by the additional recycling loop transportation requirements.

Given losses throughout the recycling supply chain, some virgin materials are still required. One study even suggests that recycled glass, therefore, requires only 13% less energy, compared to virgin glass.

Here’s the real kicker: of the 12.3 million tons of glass generated in the U.S., just 31.3% are recycled (a rate that’s lower than previous years, BTW). This is in part due to “wishcycling”, but also due to the fact that broken glass often can’t be sorted and recycled due to the liability it poses to the sorters.

Then it ends up in landfills, where it can take up to two million years to decompose, accounting for 4.3% of all municipal solid waste in the US. Poor recycling rates make the environmental footprint of glass really heavy.

Weight & Shipping Concerns

Speaking of heavy… The weight of glass may be the reason why many people like it but it is actually another environmental downfall. Yes, that bottle of kombucha might look and feel great, but getting it to your local grocery store automatically requires more transportation emissions than its plastic counterpart. Glass is also more prone to breakages, making it more expensive to ship and more likely to result in wasted product.

Additionally, the weight of glass containers plays a significant role in iots poor recycling rate. For many, it’s simply not true that glass is easier to recycle than plastic. While most large cities and denser urban areas offer glass recycling services (81% as of 2018), smaller towns in rural America do not, simply because they do not have the infrastructure to recycle it themselves nor the funding to ship such heavy materials somewhere that does.

And the number of American town refusing glass recycling is increasing due to its expense.

However, it is worth noting that this problem isn’t worldwide. Whereas the US’ glass recycling rate is incredibly poor, it’s as high as 90% in Switzerland, Germany, and other European countries,

Plastics are traditionally made from natural gas and petroleum. More specifically, they’re made from monomers like ethylene, a byproduct of the environmentally destructive practice of fracking. These monomers join as the building blocks, to come together in various polymers (structures of bonded units). In ethylene’s case, it becomes polyethylene, which can eventually become one of its derivatives, PET, HDPE, or LDPE.

These petroleum monomers, or ‘hydrocarbon feedstocks’ (fossil fuels), require roughly 14% of the world’s total oil production.

Energy Use & Production Impact

To extract and transport the materials alone produces roughly 13.5 million metric tons of CO₂e (equivalent) every year—and this is just for plastic feedstocks in the U.S.

To transform them into polymers then requires an energy-intensive process, making plastic, one of the “most energy-intensive materials to produce,” according to NPR. Like glass, plastic requires heat, but it also requires refrigeration (to the tune of -260°F), both of which typically come from electricity.

Of all American industries, plastics account for 6% of the total energy used.

That’s what plastic production consumes. Let’s not forget what it produces. For example, to refine ethylene, 213 million metric tons of CO₂e was required in 2015 in the U.S. This is roughly the same amount as 45 million passenger vehicles driving for an entire year. That’s in addition to the emission of VOCs, benzenes, toluenes, and nitrous oxides (a greenhouse gas with a warming potential 300 times as potent).

Is Plastic More Recyclable Than Glass?

A single ton of recycled plastic reduces 5,774 Kwh of energy, 16.3 barrels of oil, and 98 BTUs of energy. Those energy savings are helpful but seem rather bleak when you consider that just 9% of all the plastic that’s ever been produced has been recycled.

Even when plastic is recycled, it’s actually ‘downcycled,’ or transformed into a product of lesser quality. Eventually, the cycle can no longer continue, so most plastics can only be recycled once or twice.

Still, when comparing glass bottles vs plastic bottles, one of the big boons to plastic is its weight. Because plastic weights roughly 40 times less than glass, it’s not only much more widely recycled by municiple reycling programs, but results in significant savings on shipping emissions.

But when you consider we produce roughly 300 million tons of plastic waste annually—the weight of the entire human population—that weight decrease doesn’t really amount to much. Despite plastic being easier to recycle than glass, about 60% of it still ends up in a landfill, incinerator, or polluting our environment, releasing harmful microplastics, as well as other toxins.

According to a research made on Italian coasts, plastic waste constitutes 81.2% of the waste found on beaches, while glass and ceramic combined accounts for just 7.3%.

All in all, between production and the unfortunate fate of incineration, plastic could produce around 56 gigatons of carbon between 2020 and 2050, equivalent to fifty times the annual emissions of all American coal power plants—and that’s a low estimate.

Glass Health & Safety

While dolomite isn’t always used in glass manufacturing and is generally considered non-toxic, heavy inhalation of it is associated with a range of respiratory disorders. Similarly, silicosis, one of the oldest occupational lung diseases, is also relatively common among glass factory workers.

More concerning is the exposure to heavy metals like lead, arsenic, chromium, antimony, and selenium dust/fumes. These have been linked to a range of conditions including, but not limited to, brain cancer, nasopharyngeal cancer, lung cancer, cancer of the larynx, and laryngeal cancer. Ultimately though, there is only limited and somewhat inadequate evidence that occupational exposures in the manufacturing of glass containers are carcinogenic.

As for users, enameled drinking glasses have been suspected to contain harmful levels of lead and other heavy metals, the biggest risk for consumers is obvious: accidentally cutting ourselves.

Plastic Health & Safety

Throughout the entire plastic supply chain, health concerns are present. Just as toxic chemicals are released into the environment, they can also put workers in harm’s way, by releasing clouds of toxic vapors or causing chemical spills, fires, or explosions.

Plastic industry workers have been harmed by noise and respiratory particulates, leading to hearing issues and respiratory problems like lung disease. In some areas of the world, plastic factories have been associated with a 400% increased risk of breast cancer, thanks to toxic fumes. Workers in plastic refining tend to bear the biggest burdens, with associated health complications including cancer, genetic impacts, reproductive and developmental problems, and nervous system impairment.

On the user end, most of us likely know that plastic products are toxic, containing a cocktail of chemicals like pesticides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), heavy metals, and the dreaded endocrine disruptor bisphenol A (BPA), to name just a few.

In the EPAs list of Priority Pollutants, 78% are found in plastic.

When heated, such as in old Tupperware, these chemicals can leach into food. Some have been associated with metabolic disorders (like obesity) and problems with fertility. When it comes to glass vs plastic Tupperware food storage, plastic-free food storage options like glass are the clear winner.

Plastic can even have an indirect impact on human health, one that occurs long after we use that straw. When decomposing in a landfill or incinerated, plastic can release toxic chemicals, impacting nearby communities and resulting in environmental justice issues.

Similarly, when plastic degrades in the natural environment, the microplastics can get into the soil, water, wildlife, and humans. If you’ve ever eaten seafood, you’ve certainly consumed microplastics. Its ubiquitous nature means that in our modern age, babies are even born with pollutants and microplastics already in their system.

Even if you follow a vegan diet, microplastics can enter the human body via ingestion or inhalation simply by using a plastic bottle.

Next time you’re debating between a Nalgene or plastic-free water bottle, here’s your answer: used and/or recycled.

Not what you were expecting?

The fact of the matter is, both glass and plastic bottles have their share of enviornmental issues. Comparing the life cycle impact assessments of a non-returnable glass bottle and a virgin PET plastic bottle, the glass bottle was actually significantly higher in terms of global warming potential (4.30 kg CO2 eq to 1.86 kg CO2 eq) and water consumption, whereas a plastic bottle was significantly higher in ozone depletion, terrestrial acidification, fossil resource scarcity, and human carcinogenic toxicity.

While glass certain pulls ahead in terms of safety and thus we definitely suggest you avoid plastic consumable containers of any kind, we can’t say glass is better for the environment than plastic. New materials have a heavy impact on our planet, regardless of what they’re made of. The best thing we can do is curb our consumption of both.

When it comes to recycling glass vs plastic, the main takeaway is that we need to do better with both. Much better. Reusing both materials yourself (rather than relying on the blue bin on your curb) is the best way to ensure they actually see a second (or third or fourth) life.

By reusing the glass bottle only once, the impact can be reduced by 40% (though note this percentage significnatly decreases after second use).

Or make an even better planetary decision with aluminum, which assumes most of the pros from both glass and plastic. While aluminum has environmental problems of its own (deoxygenation in oceans and acid rain causing leaching into the environment), it’s light, isn’t made with fossil fuels, is infinitely recyclable, and requires less energy and resources to produce.

Much like rayon vs cotton, the glass vs plastic bottles environment debate has no clear winner.

However, glass has generally been the ‘chosen one’ for some time, especially when thinking about glass vs plastic containers. This is because, unless you’ve got chronic butterfingers, glass is a healthier choice. To choose the best material, instead remember the 5 Rs of zero waste—refuse, reduce, reuse, repurpose, and recycle.

If you know anyone else who’s been stumped by this puzzling packaging debate, feel free to repurpose this article by sharing it with them.