Frankly, recycling glass has a relatively low environmental benefit compared to other materials like aluminum cans, paper, cardboard, or plastic bottles. The raw commodities that make glass; sand, limestone, soda ash, and feldspar, are more plentiful than those raw inputs for other materials, yet the Glass Packaging Institute still recommends to recycle your glass bottle based on these following environmental benefits:
- Saves raw materials — Over a ton of natural resources are conserved for every ton of glass recycled, including 1,300 pounds of sand, 410 pounds of soda ash, 380 pounds of limestone, and 160 pounds of feldspar.
- Lessens the demand for energy — Energy costs drop about 2-3% for every 10% of broken glass used in the manufacturing process.
- Cuts CO2 emissions — For every six tons of recycled container glass used, a ton of carbon dioxide, a greenhouse gas, is reduced. A relative 10% increase in glass reduces particulates by 8%, nitrogen oxide by 4%, and sulfur oxides by 10%.
- No processing by-products — Glass recycling is a closed-loop system, creating no additional waste or by-products. There is no physical degradation when recycling a glass bottle, unlike paper where the fibers shorten with every re-manufacturing.
Despite these obvious benefits, I’ve read about states sending their glass to the landfill even after receiving good quality mixed cullet from their container deposit programs. The reality of the situation is that glass is heavy, and costly to transport, as well as there’s the difficulty of sorting out the glass fragments by color and transparency. One little ceramic cup can contaminate a whole load of glass.
- The recycling process starts with the consumer consuming a beverage. Hopefully, they chose something tasty like ginger beer. Anything but Heineken!
- The glass bottle is then taken to the MRF, where it is optically sorted by color and washed. You can’t mix different colored glass, or else the final product will come an odd discolored pigment after molding.
- Any glass that remains unbroken is then crushed into “flint,” and sent to a re-manufacturing plant.
- Recycled flint is combined with sand, soda ash and limestone and heated in a furnace that reaches 1500 degrees Fahrenheit, turning the mixture into liquid.
- The new liquid glass is molded to make new bottles.
- Green, amber & blue glass is crushed to less than 3/8″ and used as an aggregate, like sand or gravel for road fill. This can also be known as “Glassphalt.”