Glass – Part of our history

Glass materials have been around for nearly 5,000 years. If we know this very well, it’s because it would take more than 1 million years for a glass bottle to decompose in the environment. Glass is a safe material and is used today to store radioactive waste. Glass waste doesn’t harm to our planet–it just sits there…forever. Traditional glass is made by melting sand, lime, and soda ash at 2600-2900 degrees Fahrenheit. It is then molded, cast or blown to for the desired shape.

Apart from pyrex, crystal and other exotic materials, glass is largely used to produce food containers and flat screens for TVs, representing nearly 55% of all glass products. Plastics may have replaced glass in many applications, but glass remains the material of choice for alcoholic beverage containers. Glass is a perfect material for food and drink consumables and once used can be melted again and again to recreate the same finished product with no material degradation.

glass the perfect cycle

Source: The Glass Packaging Institute

glass continer recycling loop

Source: The Glass Packaging Institute

Glass – The value of recycling

Glass finds its main value in the recycling chain. Due to its high density and weight, glass can easily be separated from the rest of our waste, be washed, dried and melted again at high temperatures that would burn to ash almost everything else.

The main issue with producing glass is the extraordinary amount of energy required to melt the raw material. Today this energy is primarily produced by burning natural gas which leads to higher greenhouse gas emissions. When glass is melted again from its finished form, called cullet (as broken pieces of recycled glass), the amount of energy is reduced by 74%. To illustrate this, consider that if all glass production in the U.S. used 50% cullet this would be equivalent to removing the CO2 emissions of nearly 400,000 vehicles each year. Your personal glass recycling efforts matter! Recycling just one glass bottle saves enough energy to a power a 100 watt light bulb for four hours or power a television for 20 minutes.

So, we know that glass is 100% recyclable, yet the following troublesome observations have been made:

  • Only 34% of glass containers manufactured in the U.S. in 2014 were recycled
  • Nearly 40% of this 34% is downcycled to less valuable products
  • Over 50% of the glass entering our waste stream ends up in the landfill

recycling rate

Source: The U.S. Environmental Protection Agency

Glass recycling – So much to improve

So, we know that not all of our glass gets recycled. But why? It is one of our most versatile man-made materials, yet it has one main problem: it breaks. Many cities still refuse today to recycle glass for a variety of reasons, including:

  • Presence of broken glass in the recycle stream creates a hazard for workers sorting waste manually.
  • Pieces of glass entering paper and cardboard recycling operations can damage equipment.
  • Glass cannot be easily sorted by color and once colored glass is present, the entire volume of glass collected ends up being colored after being reprocessed. This mixed color glass has little to no value, and if not landfilled is downcycled to produce materials like fiberglass and ceramic tiles or is used as an additive in concrete.
  • Recycled glass is very heavy and thus is expensive to transport.
  • Municipal waste management operations often choose to send broken glass directly to the landfill.

Today many of us still believe that all types of glass types are the same and can be recycled. Unfortunately, this isn’t correct. Drinking glasses, ceramic plates, pottery, windowpane glass, mirrors, fluorescent light bulbs and more should not be recycled. When these glass types are mixed in with glass that could otherwise be recycled the entire load is landfilled because the different types of glass can’t be separated.

The solution is simple, yet isn’t available in most of our cities: dual stream recycling. This is a program where each household has two recycling bins–one for recyclable glass and another one for all other recyclable. What a difference this type of recycling program can make!


In conclusion, glass is worth recycling because of its inherent value. Check with your local recycling hauler (either municipal or private) to find out more about recycling glass where you live. If they have a recycling program in place that includes recyclable glass, make sure to follow the following guidelines so that you can confidently and correctly recycle this valuable material:

  • Recycle only the glass containers listed acceptable in your area
  • Do not recycle broken glass
  • Clean/rinse your containers

More to read:

  1. The 2016 State of curbside Report
  2. Glass recycling facts 
  3. Truth about glass recycling 
  4. Advancing sustainable materials management: 2013 fact sheet 
  5. Background information on waste glass reclamation and recycling
  6. Complete life cycle assessment of North American container glass

Author: Stephane Girois, Ph.D.