Recycling glass is the perfect use of the technology; glass does not biodegrade over time, and the materials and energy needed to make new glass from silica, soda, and lime uses more resources, and releases more carbon dioxide into the environment, then remelting and remaking new glass products from old. Glass can be recycled into new containers forever.
There are several specialized types of glass, such as Pyrex fireproof glass; this type of glass needs to be recycled separately from other types of glass. Glass also retains its color when it is melted and reformed, so green, clear, and amber or brown glass needs to be segregated. Some new recycling centers have optical sensors that can sort glass by color, but most centers separate colors at the recycling center. Once sorted, the glass is crushed into a material called cullet.
The cullet, which is crushed pieces of glass about the size of flakes of oatmeal, is sold by weight to glass re-processors. As technology improves, the ability of glass to be recycled, sorted, ground, and then remelted can entirely replace the manufacturing and production of new glass. There is no quality benefit to new glass compared to recycled, and the recycled uses significantly fewer resources.
In addition to making new glass containers, recycled glass and cullet ground to the size of pea gravel is being used as a manufacturing material in a number of products. Its use in roadbeds, and as a filtering layer in urban bioswales and rain gardens has become common; its use in concrete manufacturing brings additional benefits of improved long-term strength and thermal insulation. The strength and thermal insulation qualities make the product perfect for supporting and protecting waterlines and pipes.
With new uses being found for recycled glass cullet, and with both environmental and resource benefits to using recycled glass rather than manufacturing new, glass is a resource that can be recycled infinitely.