Is Glass More Recyclable Than Plastic?

The drawbacks of plastics are well known, with businesses and consumers alike having been discouraged from using them for many years due to their impact on the environment. In today’s post, we’re going to take a look at how plastics compare with one of their most popular alternatives, glass, when it comes to recyclability. The two materials make for a natural comparison, as the vast majority of both glass and plastic that gets recycled comes in the form of bottles. In discussions surrounding zero waste, glass is often framed as an eco-friendly alternative to plastic- but how true is this really?

Whether you’re a business trying to decide which material would be best to package your product, or a consumer trying to make more sustainable choices, our team are here to give you a comprehensive overview of the differences between glass and plastic. At the very least, we hope to convey that the question has a nuanced answer, as there are many factors that determine a material’s “recyclability”.

First, let’s go over how each material is recycled.

Glass intended for recycling is first delivered to a glass treatment plant. Before glass can be repurposed, it needs to be stripped of other materials, sorted by colour, and washed. This is achieved via a series of chutes and conveyors. Blown air is used to remove paper labels from the glass, and magnets above the conveyor detach any metals (such as bottle caps) as the glass passes beneath it. An optical sorter then uses laser technology to arrange the glass by colour, after which the glass is thoroughly washed and sent through a crusher. After the glass is crushed, the pieces are then melted into liquid and subsequently hardened into plates. These plates can be moulded into various shapes, making glass a highly versatile material.

• Glass is made from sand, limestone, and soda ash.
• Glass is an inert material, meaning that it doesn’t react to whatever substance it stores, but takes over a million years to decompose.
• In the U.K., 70% of glass is recycled, with the majority of this being bottles and jars.
• There are, however, some glass products that cannot be recycled. These include mirrors, crystal glass, lightbulbs, eyeglasses, drinking glasses, fluorescent lighting tubes, and others.

How Plastic is Recycled

Plastic is a more complicated material to recycle, given its diverse chemical makeup. There are also many sub-varieties of plastic- from PETs (such as beverage bottles) to LDPEs (such as garbage bags)- each of which undergo bespoke recycling processes. At first, these different types of plastics are sorted by infrared sensors when they arrive at the recycling plant. From then on, the process is not too dissimilar to that of glass. The plastics are stripped of debris and contaminants, before being washed. The washed plastic is then shredded, melted down, and compressed into pellets. These plastic pellets can then be delivered to manufacturers to create new products.

• Plastic comes in two categories- synthetic or bio-based. Synthetic plastics are harvested from crude oil, coal, and gas, whereas bioplastics are derived from biological substances such as starch, vegetable fats, and carbohydrates. Most of the plastic we currently use is synthetic.
• Plastic is favoured for its light weight and high durability.
• During the recycling process, plastic loses some of its tensile strength and viscosity, as the polymer chains are broken down in the furnace. This decreases its practical viability, making it inevitable that it will end up in landfill at some point.

See more: Understanding the Plastic Recycling Process in the UK – SL Recycling (slrecyclingltd.co.uk)

The Key Differences

• Glass is made from natural, bio-available materials such as sand, limestone, and soda ash. Plastic, on the other hand, is a petroleum-based material that is manufactured from unsustainable resources such as crude oil and gas.
• Glass is infinitely recyclable, never losing its quality, whereas plastic deteriorates with each cycle and will never have the same purity again after being recycled.
• Neither material is very biodegradable. Glass takes over a million years to decompose (even longer if in a landfill), while plastic takes less than a thousand years, but releases toxins that harm the environment as it does so.
• Plastic requires less energy to manufacture and is therefore cheaper than glass.
• Plastic is much lighter than glass. This means that the costs for transporting glass are considerably higher than they are for plastic.
• Glass products fail at the supermarket more often than their PET counterparts.

Our Verdict

In terms of just the material products themselves, glass is undoubtedly more recyclable. However, when taking into account the respective supply chains of those materials- encompassing their extraction, manufacture, distribution, afterlife, and reprocessing- the picture looks quite different. A single plastic bottle converts into waste faster than a single glass bottle, but to determine the “recyclability” of the material, we have to evaluate it on a macro scale. Weight is a critical factor in determining this, as a glass bottle can be as much as 40 times heavier than a plastic bottle of comparable size. This results in glass producing significantly more emissions during transportation than plastic does.

Both materials have their pros and cons. Glass is more recyclable in and of itself, but the emissions that come with its supply chain would seem to give plastic the edge overall. Plastic can also be repurposed into a greater variety of products, but isn’t being recycled enough. Ultimately, consumers should be avoiding single-use products as much as possible, to ensure the least amount of waste ends up in landfill.