Glass vs plastic: Which Material Should You Opt For?

Glass and plastic are two of the world’s most used packaging materials. In the sustainability industry, glass has a far better rapport than plastic, which is known for its heavy environmental footprint.

All glass bottles and plastic packaging consume resources and generate greenhouse gas emissions during production—especially when making new plastic or glass.

In 2019, the United Nations Environment Assembly noted that reducing the impacts of sand mining and moving towards less environmentally damaging, less carbon-intensive, more efficient circular economies in construction should be some of our top global priorities.

And although glass is almost always seen as an environmentally-friendly alternative to plastic, the conversation is much more nuanced and complex than you might have first thought.

So with that, let’s take a deeper dive into glass vs plastic, how they’re made, their environmental impact, and what it means to use these materials in your daily life.

Plastic & Glass
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Glass

Glass is a hard yet brittle substance we know best as the translucent or semi-translucent material we use in our plates, cups, windows, jars, and plenty more. It is so prevalent in our daily lives that in any house you go to, there is sure to be a glass bottle or two.

Glass can be colored, clear, and come in a wide variety of forms and shapes.

This material is unique in how it behaves like a solid yet is actually made from a liquid! It is also strong enough to become windows and floors for skyscrapers, yet at the end of the day, is still a fragile, brittle material.

It’s pretty interesting to see how much we use glass throughout all aspects of life—cooking, architecture, science, and so much more.

In eco friendly circles, glass containers are seen as environmentally friendly alternatives to plastic bottles since they are infinitely recyclable and aren’t made of petrochemicals.

A common feature in many sustainable kitchens and living areas is the presence of repurposed glass jars utilized for many different reasons—containers, decor, dry goods storage, etc.

If you’re like us and are also trying to go zero waste, you’d understand how much of a household staple glass is. Have no idea how to start with zero waste? Check out our beginner’s guide here.

But is glass really as eco friendly as we think? Not really, and we’ll see just why in a quick minute.

A Brief History of Glass

Glass is made by subjecting sand to incredibly high temperatures (think: 1500 degrees Celsius) and cooling it down to form a clear and hard substance.

Knowing this, would you believe that glass was used by human beings as early as 2600 BC? Yep! Humans have been making and using glass for thousands of years, and no one knows for sure who discovered it first.

All we know is that glass beads and rods were already being used as early as then. What’s interesting to note is that these early uses of glass were mostly found in places like Ancient Egypt, where there was an abundance of sand.

And just like many other early discoveries, maybe glass was discovered purely by accident! And what a lovely accident that was. Today, we use glass in so many aspects of our life that you probably can’t go a day without seeing at least some glass in your environment.

And although we now use glass in a very different manner than the Ancient Egyptians, the method for making glass remains largely the same, albeit a little more complex due to industrial conditions.

How Is Glass Made?

Much of the environmental impact of glass has to do with how it’s made. We know that glass can be made by heating sand to high heat levels and cooling it down in sheets, jars, etc.

But that’s only touching the tip of the iceberg. Glass made under industrial conditions is made from all sorts of materials, not just sand.

More specifically, a mixture of sand (together with glass waste), limestone, and soda ash are placed in a kiln and heated up to around 1500 degrees Celcius, sometimes even more. This allows the mixture to melt into molten sand, a state that looks pretty much like lava.

Soda ash is an interesting component of glass making. Its main purpose in the mixture is to lower the melting point of sand, which reduces the overall energy consumption of glass manufacturing.

However, adding ash to this mixture has the unwanted effect of creating glass that will not stand against water (it will melt in the water).

As a solution, limestone, or calcium carbonate is added to ensure the glass stays hard and strong. This process is why you may see typical glass referred to as soda-lime-silica glass.

Creating colors in glass requires more science. Different types of chemicals are added to the mixture in an effort to create reactions that will alter the tint and properties of the glass.

For instance, adding iron oxides to glass will create green and brown pigments. Adding cobalt oxide will create a deep blue hue and adding selenium compounds will create reds. There are plenty of other color combinations that can be made from glass, and all of them involve chemistry.

Processing glass can also involve metallic compounds to create glass that has an iridescent effect. Sometimes, glass may even be “decolorized” by removing any impurities from the sand—a technique best used to create really clear glass.

Once the sand mixture and pigments are molten, they are cooled down in sheets or blown into shapes, depending on what the glass will be used for. Very tough glass is achieved by cooling down the molten mixture very rapidly.

Countless other alterations to the raw materials and production process will create different variations of glass, each one just a little it distinct from another.

Is Glass Eco Friendly?

Although glass is often spoken of highly in sustainability circles, most of the discourse surrounding this material is unfortunately very much lacking.

The world uses about 50 billion tons of sand annually, which is twice the amount our rivers are producing—making our sand use quite an environmentally dangerous activity after all.

You might be wondering how we could use so much sand when we barely ever see any sand apart from those found on our beaches.

But take a quick look around you. Your phone? It has glass in it. Your windows? They are made of glass. Your drinking glasses, oil bottles, pasta jars, and many other items in your home that you’ve gotten very accustomed to are made of glass.

According to this 2013 study [2], mineral extraction and construction are both major contributors to climate change. And while those glass food containers in your fridge definitely don’t require as much sand as glass paneling for a skyscraper, this information tells us to look at things from another perspective.

In actuality, one of the most important regional challenges we face today is how to protect our sand and gravel resources from being overexploited due to increasing demand [3].

These raw materials, while easy to extract, are crucial to ecological balance as they provide protection against flood, help with groundwater storage and filtering, assist with food production, etc.

The moment we take a look at glass as a scarce resource, it ceases to become the quintessential environmental tool. And frankly, it’s quite a jarring thought to think that many of our preconceived notions about the sustainability of glass aren’t actually rooted in factual information.

All of this still hasn’t touched on the fact that glass production generates emissions and uses fossil fuels.

As established, creating glass requires a lot of high heat. And in industrial applications, a lot of this heat is generated through fossil fuels—another unsustainable resource.

While glass itself may not be made from a petrochemical, natural gas is still used to create our glass bottles, still generating tons of carbon emissions annually.

On top of that, glass is heavy! Transportation is yet another big part of any product’s carbon footprint, and the heavier an item is, the more environmentally costly it is to transport.

Ready-to-drink beverages are some of the best examples of how weight can contribute to environmental impact.

Beverages, as they are predominantly made from water, are already heavy and a challenge to transport.

Container glass packaging only adds to each product’s weight and will directly contribute to how eco friendly the whole supply chain of glass truly is. After all, a glass bottle is much heavier than one made from plastic or aluminum.

Can Glass Be Eco Friendly?

The topic of glass sustainability is a difficult one to broach, especially in the context of glass vs. plastic. However, there are some instances when glass can be eco friendly!

Like plastic, glass can also be recycled. And in fact, we mentioned that glass production typically starts with sand and recycled glass pieces together. Using recycled material to create glass containers is one of the best ways to improve the environmental impacts of this product.

If the production process starts with recycled glass, a huge chunk of the impact is taken out because no new sand is required to make it.

Unfortunately, we recycle glass at a measly rate of 31.3%. According to the EPA, the United States recycled 3.1 million tons of glass in 2018, which roughly amounts to a third of the total glass waste generated in the same time period.

This means two-thirds of the glass products we use are still left unrecycled.

So if you do end up opting for it, just make sure to recycle glass properly to increase the chances of it being reused in new products.

Plastic

Now let’s move on to one of the most controversial packaging materials in sustainability: plastic.

Plastic bottles are one of the most disliked methods of packaging, especially when you’re trying to shop more eco friendly. If you are currently practicing a zero waste lifestyle, then you know quite well the dangers of plastic and why we should avoid it if we can.

But there’s actually more to plastic than what most of us know on the surface level.

Plastic is an incredibly versatile material that has somehow found itself in every part of modern living. It’s in our kitchen appliances, our cellphones, medical equipment, cars, and so much more.

Some examples of plastics we use today are low-density polyethylene, polystyrene, polyethylene terephthalate, and polypropylene, among others. These can come in the form of plastic bottles, plastic containers, styrofoam boxes, and even plastic lumber!

In essence, plastic can simply be described as a synthetic polymer. Polymers are a chain of monomers and can be found in our natural environment. Some natural polymers are rubber, silk, and wool.

And if ever you’re confused about it, just remember that all plastics are polymers but not all polymers are plastic.

A Brief History of Plastic

Unlike glass, people have only been using plastic for about a century or so. Because plastic is a synthetic material, it was only through innovation and necessity that plastic became such a relevant part of our daily lives.

In the 1860s, Alexander Parkes created the world’s first man-made plastic, Parkesine. It was meant to be a plastic substitute for materials like ivory and horn but the product was not met with commercial success.

John Wesley Hyatt further improved this innovation and created something called celluloid, which had more versatile applications and was the more commercially successful variant.

Nevertheless, these plastics were still made from natural components and it wasn’t until the early 1900s that we created a wholly synthetic plastic called Bakelite. Bakelite was created from formaldehyde and phenol, and its applications are mainly geared toward electrical equipment.

In the next decade following this initial discovery, synthetic fabrics like rayon came into the picture. Although rayons are fabrics and not your typical plastic containers, they’re still important in understanding how our plastic industry came to be as large as it is today.

While there were already polymers existing in the market as early as the 1920s to 1930s, it really wasn’t until the second World War that plastic began to take hold of our daily lives.

Plastic was even used during the war as a way for countries to gain an upper hand against their opponents by protecting formulas as state secrets. Many synthetic materials like nylon and rayon were popularized during the war.

After the war, plastic quickly made a transition to becoming a commercially produced product for the consumer market. During this time, plastics we use today like high-density polyethylene were also developed, although not nearly as refined and perfected.

How Is Plastic Made?

Plastic production may begin with a wide variety of synthetic or bioavailable materials. It can be made from cellulose, crude oil, salt, and natural gas—although oil and gas are the most commonly used ones.

These virgin materials are actually part of the reason why plastic gets such a bad reputation for use in packaging because these are finite resources and will eventually run out.

Making plastic is a highly chemical process that generally begins with oil extraction (although other materials like biomass could also be used). The extracted raw material is then refined into different petroleum products.

The crude oil is then heated up in a furnace and then distilled, which separates the oil into lighter components referred to as fractions. The goal of the refining process is to create monomers, which are the building blocks of all polymers.

Ethylene and propylene are a few examples of frequently used monomers in plastic production.

These monomers are further processed through polymerization, which is the process of connecting monomers into chains to create polymers. This can be done through addition polymerization or condensation polymerization.

The polymers are then extruded and melted, which forms the plastic that can be cut up into pellets for further melting and processing. Once the new plastic has been successfully cut into pellets, it can then be melted (again) and molded into virtually anything (e.g., a plastic bottle, bags).

This is an incredibly simplified version of how plastic is made, and industrial production is no doubt more complex and intricate.

Unfortunately, the entire process generates greenhouse gas emissions and has a huge carbon footprint, making it not sustainable from an ecological standpoint.

Is Plastic Eco Friendly?

Plastic and eco friendly are two words that you do not often hear used together, mainly because plastic is seen as an unsustainable packaging option.

And if we really think about it, plastic isn’t eco friendly at all! From the very beginning of production, it already takes up a lot of natural resources that we can’t regenerate.

In addition, refining oil into monomers also takes up a lot of energy and generates plenty of greenhouse gases. And when we consider how prevalent plastic use is, the greater picture doesn’t look too good.

But perhaps one of the most distressing issues about plastic is plastic waste.

Plastic does not have the best life cycle assessment. Most types of plastic will not biodegrade under normal conditions and will remain in our environment for the longest time. A common belief is that all plastic that has ever been made is still around, and they’ll still be there long after we’re gone.

However, thanks to innovation and research, there are now certain types of plastic that will degrade under industrial conditions. These plastics are typically biobased and are turned plastic through unique processes.

Now, you might be wondering, what about recycling? In our assessment of glass, recycling seemed to help with the global warming potential of the material, and doesn’t the same thing apply here with plastic?

Ideally, it should! Chucking plastic into the recycling bin is an easy enough thing to do, right?

Unfortunately, there are a lot of drawbacks to plastic recycling. One is that plastic degrades as it is recycled. This means that the more plastic is recycled, the lower its quality eventually becomes.

This does not happen with glass since glass can be recycled indefinitely without any reduction in quality. If we’re only talking about recycling glass vs. plastic, then glass is the easy answer.

Another issue is the really low recycling rate of plastics overall. According to the latest data by the EPA, the United States only recycled around 8.7% of plastics in 2018. Some types of plastic, like PET bottles, have higher recycling rates at about 29% or so.

The recycling differences in glass vs plastic are incredibly important whenever choosing between the two materials, so make sure to always take them into consideration.

Low recycling rate and improper waste disposal contribute to environmental degradation in more ways than one. Perhaps one of the most notorious evils of plastic is its uncanny ability to end up in places where it shouldn’t be.

Plastic has been found in the stomachs of birds, and whales, and it clogs up the digestive systems of countless other animals. Even the microplastics that your polyester sweaters shed may eventually end up in the stomach of fish!

This, in itself, may be enough to deter you from buying plastic.

Regardless, there are some instances when plastic is the more practical choice. Medicine, for example, requires a lot of plastic. The face masks that have been a staple in most households over the past two years are made of plastic, after all.

Plastic is also required for optimum sanitation. When dealing with dangerous medical substances, it’s best to use plastic for easy disposal. Plastic is also used to prevent cross-contamination, among a host of many other medicinal uses.

But if the environment is our only consideration, plastic is not eco friendly at all. Right from the extraction process up until disposal, creating and using plastic emits plenty of carbon dioxide and pollutes our environment—not exactly what you’re looking for in an eco friendly material.

Nevertheless, there could be instances where you can reduce the impact of plastic such as using recycled plastic or repurposing your plastic containers at home.

Glass Vs. Plastic

So, in the conversation on glass vs plastic, which material comes out victorious? Is it the plastic bottle we’ve grown to despise? Or is it the glass containers that we’ve grown to love yet have surprisingly more environmental impact than we initially thought?

Unfortunately, there’s still no clear answer. After an in-depth analysis of both materials, there’s no clear winner as to which material is the best from an environmental standpoint. Both of these materials have environmental effects, and consequences are always present regardless of which option you choose.

Our advice then is to choose which one fits your needs the best. Some people will opt for glass because it isn’t processed with toxic chemicals, which most plastics tend to be. Therefore, glass is the better option when it comes to making a healthier choice.

And once you’ve decided, the second layer of advice we can give is to buy recycled glass or plastic. Our personal recommendation would be glass, but if this is not practicable for your lifestyle, then choosing repurposed plastic may be the second best option.

Final Thoughts

Glass vs. plastic; is there a clear answer to which of these materials you should use?

Ultimately, the choice is up to you. The glass vs plastic conversation is one of the most controversial topics in sustainability, and it is so for a reason!

But if there’s anything we can take away from this discussion, it’s that things are rarely ever as they seem. As it turns out, virgin glass can be just as problematic as plastic jars, albeit in a different manner.

And as with anything in sustainability, we always need to exert more effort in uncovering the truth. There are no quick and easy solutions to our climate issues, and if we want true change to happen, we need to deal with the issues through a systemic approach.

Regardless of what you decide, just know that there are rarely any black and white answers to our questions.

In choosing glass vs plastic, just make sure they’re recycled properly and that you’re making the most prudent choice for your lifestyle.

Resources:

  1. https://pubs.acs.org/doi/10.1021/es402618m

  2. https://www.sciencedirect.com/science/article/pii/S259033222100230X#bib7

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