Glass Vs Plastic, Which Is More Sustainable?

The glass vs plastic debate is one that seems to never get old with us folks trying to go green. But if your hunch is telling you that glass is probably the winner here, I would think again! There is a lot to consider when deciding on which material is better. This includes the environmental impact of the product, its durability, price range…etc.  

We need to take a good long look at both materials before we can agree on which is better, glass or plastic. 

What is plastic?

Okay…So what is plastic anyways? Plastic is a petroleum-based product meaning that it comes from fossil fuels, a nonrenewable energy source and a huge driver of climate change. This doesn’t include bioplastics like PLA which can sometimes be mixed in with traditional plastics and is sourced from corn or sugarcane.

To make plastic, crude oil or natural gas is treated and converted into hydrocarbon monomers like ethylene or propylene. These monomers are chemically bonded into long chains called polymers. The different structures of these monomers and polymers can determine what kind of plastic you have. And there are tons of different kinds of plastic out there! But the seven major types of plastic are:

  1. Polyethylene Terephthalate (PETE)
  2. High-Density Polyethylene (HDPE)
  3. Polyvinyl Chloride (PVC)
  4. Low-Density Polyethylene (LDPE)
  5. Polypropylene (PP)
  6. Polystyrene (PS) 
  7. Other plastics (ex: bioplastics)

When compared to glass, plastic is light and durable. It’s also cheaper to ship!

Is plastic eco-friendly?

Plastic containers of frozen mixed berries in snow - red currant, cranberry.Pin

As plastic has become more and more common, it’s left behind a massive carbon footprint on our planet. To start, the contamination of our air, waterways, and topsoil with crude oil and toxins is a common by-product during the plastic extraction/manufacturing process. In fact, 14% of all air pollution in the United States is from the plastic industry!

When a plastic item breaks down in a landfill or degrades in our waterways, thousands of microplastics are released into the environment and can bioaccumulate up the food chain. Microplastics are EVERYWHERE, even in your tea!

Plastic can take anywhere from 450 to 1000 years to decompose in a landfill. While this number might seem low compared to glass, we have to remember that plastic is leaching toxic chemicals into the environment in the process.

But the kicker with plastic is that, unlike glass, most plastic is not fully recyclable. Only certain kinds of plastic can be recycled such as PET or HDPE plastic. Most plastic, although having the infamous recycling arrows on the product, will end up in a landfill at the end of the day. When you think about how only 9% of the world's plastic is being recycled it can really get one down in the dumps (no pun intended). 

When compared to glass, plastic is also worse for human health. Many plastics contain BPA, a chemical well known to disrupt natural hormone production. This discovery has led to tons of BPA-free products in the marketplace, all marked as a safer option (like Tritan plastic)!

What is glass?

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Image: The Eco Hub

Would you believe me if I told you our sandy beaches actually turn into glass? It’s true! 

Glass was actually first discovered by accident around 3100 BC when someone was trying to make stone out of sand… and the silica in the sand turned to glass! The Romans were also recorded using glass as a substitute for marble and other expensive stones in their buildings. We’ve come a long way since then. These days glass has tons of practical uses as jars, bottles, windows, and more. 

The manufacturing of glass is also quite complex. At the beginning of the process, a mixture of raw minerals like sand, limestone, chalk, potash, and copper are melted together (at around 1500°C). The molten glass is then drawn into a large “batch” pot where the raw materials are thoroughly mixed together. The mixture can then be reheated and shaped into different forms depending on its purpose. 

In some cases, dolomite is mixed in to make the product more heat resistant. While this is effective and dolomite is generally considered non-toxic, heavy inhalation of the chemical is linked to respiratory disorders.

The final step in the production of glass is to transport the product to a facility where it can be washed and sterilized and then transported again to a distribution center or store to be put for sale. Although this whole process is water intensive and definitely creates emissions (for reference, it takes about a liter of gasoline to make 1 kg of glass), plastic is still worse off in my opinion when it comes to the environmental footprint.

Is glass eco-friendly?

So what are the environmental benefits and downsides of glass? You probably won’t be shocked to hear that this answer isn’t super straightforward. The manufacturing of glass requires a significant amount of natural resources and non-renewable minerals. 

One of the most interesting things about glass is there is actually a shortage of it! As I mentioned earlier, glass is made from sand - and only a specific kind of sand can be transformed into glass. Sand is the second most consumed resource out there, and it's disappearing fast (we go through 50 billion tons of sand every year). Removing sand from a natural environment can also disrupt the surrounding ecosystem and lead to erosion and/or flooding. With this in mind, glass does NOT come from renewable resources. 

On the flip side, glass is 100% recyclable!! 

But perhaps best of all, it can be recycled over and over again without any loss in the quality of the final product. Sometimes, glass will also be reused as a landfill cover to control offensive smells and deter pests. While effective, using glass to cover landfills doesn’t really help the environment because the glass can’t be reused again after serving as a landfill cover. 

The moral of the story is when you recycle glass you’re helping to reduce your personal carbon footprint and save energy by conserving a nonrenewable resource a.k.a., sand! 

But there is still more to the story...

In the US, we’re not that great at recycling glass. A study found that in 2018 US citizens only recycled 31% of its glass containers while Switzerland recycled 94% that same year. This is partially because some glass items can’t be recycled in US processing facilities. These include fish tanks, lightbulbs, windows, mirrors, and eyeglasses! This means that if you bring a glass item out for curbside recycling, it might end up in a landfill regardless.

Another issue with glass recycling is food contamination. If there is food or beverage residue on your glass jar for example it can’t be recycled. I have heard so many stories about recycling facilities having to toss away a perfectly good batch of recyclable materials because there was contamination in the bin. 

Once in a landfill, glass can take up to one million years to decompose in the environment! This is why it’s so important to remove the lid and rinse out the container of all your glass jars before recycling them. 

If you’re ever in doubt if you can recycle your glass item or any item for that matter, call or visit your local recycling center to confirm their recycling standards.

Which is better, glass or plastic?  

Pros and cons of glass

PROS

  • Most kinds of glass are fully recyclable as long as there is no food contamination.
  • Glass is heat resistant.
  • Glass can last a very long time and be reused over and over.

CONS

  • Glass is heavier to ship and can create more carbon emissions during transportation as a result.
  • Glass can sit in a landfill for up to 1 million years, although it won’t leach toxic chemicals during the process.
  • Glass is less durable and prone to breakage compared to plastic.

Pros and cons of plastic

PROS

  • Plastic is non-breakable and cheaper to make and ship.
  • Plastic has tons of practical purposes in the construction industry, medical field, and safety equipment.
  • Plastic products tend to also be cheaper than glass at stores.

CONS

  • Plastic emits fossil fuels in the production process. 
  • Most plastics can’t be recycled in curbside recycling programs.
  • Plastic often contains potentially toxic chemicals like BPA and other endocrine-disrupting toxins. There is also a risk with plastic that toxic chemicals can leach into our food, especially when exposed to heat.
  • While plastic breaks down in the landfill it can leach toxic chemicals and will break down into microplastics which bioaccumulate in food chains.

A Final word on glass vs plastic

The bottom line is to use glass when you can and avoid buying new products altogether. 

Glass can be recycled and isn’t as toxic to produce (although it’s not completely free of toxins and chemicals). Glass also comes from a nonrenewable resource that we will eventually run out of. Plastic, on the other hand, is durable, cheap, and has tons of different practical uses.

However, plastic also emits a huge amount of fossil fuels during production, can have negative impacts on human health, and breaks down into microplastics at the end of the product's lifecycle.

In my opinion, the most important R in the five Rs of zero waste is refuse. So when possible, avoid buying new glass or plastic products unless you really need to. 

If your Tupperware or water bottle needs a replacement, there are so many other options to consider like an eco-friendly water bottle or trying a zero-waste swap! And there is always something eco-friendly to do with your old plastic containers and of course you can opt for plastic-free storage containers too.

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