Is glass environmentally friendly? It’s complicated!

  • Date: May 14, 2022

Glass is often touted as a reusable replacement for plastic. It is an extremely popular choice in the zero-waste community and is used for many different items from travel coffee mugs to drinking straws. But is glass environmentally friendly? Despite having the ability to be endlessly recycled and reused, it also is questionable in terms of emissions associated with production and transport. Here we take a deeper dive into the ‘green’ credentials of glass. 

Does glass biodegrade?

A material is biodegradable if it can be broken down naturally by microbes. Glass is not biodegradable – although this does not mean it will not breakdown at all. Some physical conditions can make it glass degrade. 

If glass ends up in sea the physical stress it comes under will gradually wear it down. Sharp edges will become smooth, and it gains a frosty appearance. However, if your glass bottle ends up landfill it will most likely outlive you by quite some time! It will persist even longer in landfill as these are more protected from the environmental conditions that would usually speed up any breakdown.

Can glass be recycled?

Some glass items can be recycled, some can’t.  Glass used to make drinks bottles, and suchlike is fully recyclable – and can be recycled time and time again. They even manage to retain their quality, no matter how many times they have been recycled. This makes it one of the most celebrated ecofriendly materials. It is also one of the simplest materials to recycle with regular curbside pickups.

Glass that is used to make drinking glasses, for example, cannot be recycled. Unfortunately, the glass used to make them is different. It is tougher and contains different chemicals – recycling them is not possible so they need to be re-used in different ways.  

So, how is glass bad for the environment?

Quarry-related pollution

Despite being non-toxic and endlessly recyclable, some elements of glass make its ‘green’ credentials questionable. The main issues with glass crop up in its manufacturing.  Glass is made out of natural resources – mainly sand, soda ash and limestone. All these need to be extracted, leading to disruption to the lives of local animals and plants. Limestone quarrying, for example, has been found to affect the pH of river water and vegetation growth.

Glass production is energy intensive

As well as the local pollution when quarrying the raw materials, large amounts of energy is also used when making glass from scratch compared with producing recycled glass. Making virgin glass – that is new glass made from its constituent parts – requires much higher temperatures than recycling glass. As well as requiring energy, it also releases large amounts of greenhouse gases which contribute to climate change. It is estimated that recycling glass requires 40 percent less energy than making virgin glass due to the lesser temperature required to melt the materials. As well as limiting the pollution associated with quarrying natural materials, recycled glass is better for the environment in an energy efficient way.

Transport emissions of associated with glass

Glass is also extremely fragile making transport more awkward. More packaging is needed than when transporting items made from other, more sturdy materials. Although eco friendly packaging is becoming more common, often the protective packaging is plastic-based. Glass is also heavier than its plastic counterparts – making the environmental impact of transporting it a lot greater.

Sharp sea glass

As mentioned, after use glass can make its way into the sea by several different means from beach picnics to hurricanes. Glass is thought to be less dangerous to sea creatures than degrading plastics,. Animals are more likely to try to eat or be tangled up in plastics. Glass can be dangerous to sea creatures in other ways – the sharp edges can pose a significant hazard. However, as mentioned previously the tumbling of glass in the ocean smooths the edges reducing the danger as time passes.

The bottom line

Glass is a wonderful material. However, despite being lauded for being non-toxic and recyclable it also has significant downfalls when it comes to environmental impact. Emissions from production and transportation raise questions about how environmentally friendly it really is. However, no material is perfect (apart from maybe cork!) and despite these environmental impacts, glass is still an ecofriendly material in several ways. If possible, try and stick to recycled glass to reduce the energy required or, even better, reuse the glass items you already have!