The problems of plastic waste are well-known – that’s where glass comes in, the popular plastic alternative. Although it tends to be more expensive than plastic, glass can be used as an alternative for many of the single-use products typically made from plastic, including bottles, storage containers, and even straws.
If you’re looking for a sustainable replacement for plastic, choosing glass instead might seem like a no brainer. But, is glass actually a better option? As always is the case when talking about sustainability, the picture is more complicated than it first appears. Luckily, we’ve pulled together everything you need to know about glass, its environmental impact, and how it stacks up against plastic.
What is glass?
Odds are that you have plenty of glass in your home. It’s used to make windowpanes, drinking cups, jewelry, kitchen and tableware, bottles, screens, mirrors, decorative items… the list goes on and on.
Glass is made from sand or, more specifically, silica and often contains other minerals too, such as limestone, soda ash, or pellets of recycled glass (cullets). These are heated to very high temperatures in a furnace, until they turn into a thick liquid. While it’s still hot, the glass can be blown, spun, floated, or poured into moulds for shape. Once it cools it becomes hard and brittle and can no longer be shaped unless it’s heated again.
But even then, glass isn’t a solid, despite what your fingers might tell you. It is, in fact, a liquid, which is why the glass at the bottom of an old window will be thicker than it is at the top. While it flows extremely slowly, it is gradually moving down with the pull of gravity.
Glass first appeared thousands of years ago. Originally used to make small beads for jewelry, advancing techniques meant it became a sought-after material for vessels and, later, windows.
For much of its history, glass was considered to be a luxury item. Glassblowing requires real skill and the fragile nature of the material made it hard to transport, as well as an impractical item for poorer households. But with the advent of mass-manufacturing techniques at the end of the 19th century, glassmaking became easier and more affordable. At this point, glass became a common item found in most homes.
Glass isn’t only used to make common household items. Because it can be shaped easily and is non-reactive, glass finds many applications in science, medicine, and industry.
Why glass is better
As a reusable material, there are many positive points to using glass.
1. It’s recyclable
Perhaps one of the biggest plusses that glass has, from an environmental point of view, is that it’s endlessly recyclable. Some materials can only be recycled a handful of times before they become useless – including many types of plastic. But even broken glass can be melted again to make new items.
Additionally, most people know that glass can be recycled and there’s already a good level of infrastructure in place to collect used glass and turn it into fresh products. This means that the rate of recycling is higher for glass than for many other materials. The UK, for example, already recycles 68% of its glass [1]. That’s compared with 32% of UK plastic [2].
Even when the glass is mixed with too many other materials to be recycled into new glass, it can usually be made into aggregate for use on building sites.
2. It’s reusable
While glass can be recycled to make new items, that still uses energy. Fortunately, glass can also be reused. It’s easy to clean and disinfect, meaning it can be reused indefinitely in its existing form, as long as it remains unbroken.
On a household scale, this means that old bottles and jars can be repurposed as storage containers or decorative items. If you are lucky enough to have a milk delivery service in your area, you can usually return their glass bottles to be reused. Other companies offer return schemes for glass packaging as well.
3. It’s used in products that mitigate climate change
Glass is also important for many products that are used to reduce global emissions. For instance, solar panels, photovoltaic panels, and wind turbines all use glass components and are helping in the move away from fossil fuels.
Better home insulation is another vital step in carbon footprint reduction. It turns out that glass is also a good insulator and is often used to improve the energy efficiency of buildings.
4. It’s safe
One of the key issues with plastics such as BPA is that they leach potentially harmful endocrine disruptors into food, drink, and beauty products.
Glass, in contrast, is stable even when heated and can easily be cleaned. This makes it a safe material to use for packaging food, drink, and cosmetics.
But what about the downsides of glass?
Ok, so glass is obviously a great material – it can be recycled, is safe to reuse, and is a component in products that are helping to reduce our carbon footprint.
But of course, that isn’t the whole story. When looking at whether a material is sustainable (and therefore a better alternative) it’s important to look at its entire lifecycle and unfortunately, glass some some pretty big issues when compared with alternatives such as plastic or aluminium.
First off, glass is a heavy material and that means it takes more energy to transport than lighter alternatives. It’s also prone to breaking during transport – which can make its lifecycle very short indeed.
Also, while glass can be recycled and reused, not every bottle is disposed of responsibly. Plus, it takes a long time to break down in landfill. Archaeologists have found pieces of glass that are thousands of years old.
Similarly, the production process for glass is an issue as it takes a lot of energy to heat silica to the necessary temperatures and the process releases high amounts of emissions, including carbon dioxide, a greenhouse gas.
A 2020 study [3] compared the lifecycle of various types of drinks container. For each category – fizzy drinks, milk, and fruit juice – glass came out worst from an environmental point of view. Virgin glass had the most impact, but recycled glass had the second most. In every category, the plastic option had less of an impact than glass (although more than recycled aluminium cans, Tetra Pak, or cartons).
Another 2020 study [4] compared milk bottles made from glass, returnable glass, and single-use plastic – one made from PET and the other from recycled PET. Even if the glass bottle was reused 8 times, its environmental impact was higher than the bottle made from recycled plastic. On the other hand, when a marine litter indicator was added to the assessment, the study found that returnable glass became the preferable option.
While these studies only focused on one sort of glass use, it is a reminder that sustainability is complicated.
So why choose glass?
Although glass does have advantages, it also has some downsides. So, why might you want to choose it?
Whether you choose to opt for glass as an alternative ultimately depends on your own environmental goals, as well as the resources that are accessible to you.
If you’re comparing a single-use item with one that you’d keep long-term then glass might be a good choice. Although it can break, glass is still more durable than plastic, so you might opt for a glass item that you would continue to use over a plastic item that would be discarded straight away.
If you’re concerned about the potential health risks of plastic packaging (such as endocrine disruptors leaching into your food or makeup) then glass is definitely a good option.
If you want to reduce plastic pollution in the oceans then again, glass is a better choice. Glass doesn’t break down into microplastics and, being heavier, is less likely to wind up in our oceans.
If the recycling facilities available where you are don’t offer an easy way to recycle plastics then you might opt for glass packaging. If, for instance, you have access to a milk delivery service that will reuse your bottles then this may make more sense than choosing plastic milk containers.
At the end of the day, however, there might be other options available to you that are more sustainable than using glass, such as drinks cartons and recycled aluminium cans. When it comes to beauty products, an increasing number of brands are using metal packaging – while heavier to transport than plastic, it is lighter than glass and it is also recyclable. Some brands even use cardboard, which has the advantage of being light and biodegradable.
The final verdict: is glass a better alternative?
As with most things sustainability the answer to this question is both yes and no. In some instances, glass can the environmentally friendlier option but lifecycle analysis indicates that glass isn’t necessarily the best alternative.
Of course, there are times when you can’t avoid glass. In that case, you can help to reduce its environmental impact by being mindful of how you use and dispose of it. Keep it for as long as you can, washing and reusing it as much as possible. In some instances, this can be a really important element of a lower footprint lifestyle.
And if you can’t use it any longer, make sure you send it to recycling so it can have a second lease on life.
