Is Glass really eco friendly?

Instinctively, I always reach for a glass bottle rather than plastic. It feels more environmentally friendly. But is that really the case?

Plastic tends to get a really bad rep from environmentalists - microplastics have been found from the summit of Mount Everest to in the deepest oceans.

But it doesn't have to be this way.

Some modern plastics can be recycled too. They are known as PET or rPET, and you can put these in your recycling bin. Our jars are 70% rPET, 30% PET.

So is glass better than PET/rPET?

We went in search of the answer...

There's no going "half pie" on this issue. It's very important to us. We use PET and rPET currently, and for my own peace of mind I needed to know if we were doing the right thing.

We compared glass and PET/rPET (the plastic we use for our jars) from several angles.

1. Recyclability
Both plastic and glass are easy to recycle in New Zealand. They are collected by roadside in most parts of the country.

PET is a closed loop, and the recycling process turns it into many different products from containers (jars such as ours) to textiles (clothes, carpets, etc.).

Currently, New Zealand has only one main glass recycling manufacturer in Auckland.

"This can make it logistically and financially difficult for many parts of New Zealand, especially in the South Island, to get glass recycling up to Auckland.

Consequently, vast swathes of the glass that South Islanders put out to recycle never gets to Auckland and so never gets recycled back into bottles.

Although glass is infinitely recyclable, it’s quite fussy. Any contamination of the glass with other materials can make it impossible to recycle."

Sometimes Smashing, Sometimes Crushing: The story of glass in New Zealand - The Rubbish Trip

If it’s not being turned back into bottles, then what happens to all that glass collected for recycling?

Most of New Zealand’s “recycled” glass is crushed and used as a fill in road building. But once the glass is embedded in a road, you can never get it back again and you’ll need to mine more silica sand if you want more glass. For this reason, using glass in roads is considered to be ‘down-cycling’, not recycling.

The great thing about both PET/rPET and glass jars is that you can use them again and again IF recycled responsibly.


2. Energy to Manufacture and CO2 Produced

The energy to produce glass is massive. Glass melts at 1,500°C - 1,600°C it consuming 1.1 KwHr of energy to manufacture one kilogram. Another 25-30% of this energy is used in the glass factory as the glass has to be kept hot as it is moulded and annealed (when you make glass soft by heating it then slowly cooling it).

Natural gas furnaces used in glass manufacturing produce 275gms of CO2 for every kilo of glass made. The decomposition of limestone and soda in the glass making process releases another 185gms of CO2 per kilo of glass. There is 90g of CO2 produced for every 196g glass jar made. This may not sound a lot, but the glass industry in the UK in 2003 produced 900,000 tons of CO2. As much as 195,000 cars annually.

"the total energy to recycle a PET jar is around 165 times LESS than a glass jar"

In the manufacture of PET jars there is negligible CO2 produced per kilo. And because the jars are 7.5 -10 times lighter than glass, the CO2 produced per jar is non-existent. To recycle PET, it must be heated to 250°C to melt. Because the jar is only 26gms, the total energy to recycle a PET jar is around 165 times LESS than a glass jar.

3. Weight

Our square PET honey jars weigh 26g versus the lightest available glass 500gm honey jar weighing 196g, this is 7.5 times as much as PET jars. This extra weight costs resources and energy to freight it not only to our export customers but also to us.

Glass food jars supplied in New Zealand are manufactured in Asia and Europe. The high cost in energy and resources to ship glass from these distant sources is a significant environmental issue. PET resin is imported into New Zealand in bulk in shipping containers and then blown into jars here.

If all honey packed into retail packs in New Zealand were put in PET, it would require 23 shipping containers of PET resin, but if all honey were packed in glass jars, it would require 720 shipping containers, 30 times more than PET.

"if all honey were packed in glass jars, it would require 720 shipping containers, 30 times more than PET."

When exporting our honey, we can put 3,200 cartons of honey in PET jars into a shipping container but we can only put 2,250 cartons of glass jars into a shipping container because of the extra weight of the glass jars.

If all honey packed into retail packs in New Zealand was packed into glass, it would be an extra 3,750 tons of weight to be transported. From the glass factory, to the port, on the ship to New Zealand, to the honey packer, to then be moved to the market, either local or, back onto a ship for export.

 4. Sand mining impact on the World's Resources

Glass is made from all-natural resources, such as sand, soda ash, limestone and recycled glass. Anytime we take sand out of its natural habitat, you break a chain in the ecosystem. Even worse than that, when sand is removed, local communities are more susceptible to erosion and flooding.

Worldwide there is a significant problem with sand mining that is at the heart of all glass manufacture.

Neither are the ultimate answer, but we can say hand on heart that PET/ rPET is the best choice right now.

We have assessed how we can use minimal output and energy and will continue to review this as technology improves.

Now the ball is in your court to recycle responsibly!

  1. Soak your jar in hot water when you are done
  2. Use it at home for or put it in the recycling bin or take it to your local recycling center.
  3. Close the loop. Give the jar another life!

If we can work together as producers and consumers we can be responsible plastic users and help reduce our waste footprint.

Kelsey, Airborne Honey