Eternal Renewal: Glass Recycling’s Energy Shift Challenge

Glass recycling, an infinite process challenged by the energy transition

A dump truck unloads its collection of glass thrown away by individuals into glass recovery containers, unloading its collection of glass thrown away by individuals into recovery containers. Recover the glass, treat it, work it and make new bottles: although this material is infinitely recyclable, its reuse remains energy-intensive, which manufacturers are trying to reduce consumption of.

The parade of dump trucks is incessant: at a rate of four per hour, they dump with great noise the glass thrown away by individuals into the glass recycling containers. The glass recycling factory receives 110,000 tons of raw glass per year, according to the general director of the company. There are around 60 kg of impurities per toe: they remove the caps, the labels, the plastic, surveying the hills of waste formed as the trucks dance, on the processing site that the company manages.

Once the impurities are removed, automated machines separate the white glass from the colored glass to form two large piles of cullet. It is then transferred near there, to a glassware factory, owned by the world’s third largest producer of glass packaging for drinks and food products.

Less energy-consuming material

Once through the glassworks doors, the cullet is transported to the ovens, where the temperature is maintained at 1,350 degrees. This recycled material is used in the manufacture of a large proportion of bottles, some containing up to 86%. Champagne, cognac, high-end spirits… In oppressive heat, the employees of the glass factory ensure the production of 340 different models of bottles, on long mechanized production lines.

If the composition, which melts at the start of the chain, varies depending on the desired final object, the presence of cullet makes it possible to limit the sand requirements. For approximately 100,000 tons of cullet from the waste treatment center, they use 50,000 tons of sand per year.

It is in their interest to recycle cullet because melting it uses less energy than melting raw materials, assures the director of the glassware factory, keeping a good distance from the burning walls of the gigantic furnaces. A ton of recycled cullet is 180 grams less CO2.

The manufacture of glass, however, remains energy-intensive, with ovens which heat continuously and 80% with gas, the rest with electricity. In recent months, faced with gas supply difficulties linked to the war in Ukraine, and to be able to maintain the rate of ten bottles produced per second, the factory has been forced to resort to fuel oil.

It’s not something they want to do, stating the company’s objective to reduce CO2 emissions by 50% by 2030. If they want to achieve this, using cullet is not enough. They are going to move the kilns towards electric or more electrified technologies, referring to ongoing tests they perform. They are also seeking to strengthen the circularity of packaging by supporting local communities so that they recycle more, by raising awareness among the population in order to recycle more cullet.

The presence in this region of a factory manufacturing 300 million bottles each year, and an associated waste processing center, is an asset in the eyes of the communities which manage glass collection. They must constantly remind themselves of the sorting instructions, and in terms of communication, glass recycling is anchored in the history of the local community.

The science of glass recycling

Glass recycling is a fascinating scientific process that involves transforming waste glass into reusable materials. It begins with collection and sorting, where glass is separated by color and type to ensure quality recycling. Then comes cleaning and crushing, breaking down glass into small pieces called cullet. The cullet is melted in furnaces at high temperatures, where it can be molded into new glass products.

The science behind glass recycling is intricate and involves understanding the properties of glass, such as its melting point and chemical composition. Additionally, advancements in technology have improved the efficiency of glass recycling processes, reducing energy consumption and environmental impact. By recycling glass, we conserve natural resources, reduce greenhouse gas emissions, and decrease the demand for raw materials. Embracing the science of glass recycling is essential for creating a more sustainable and circular economy.

That is why tons of glass junk sent by dumpster rental trucks arrive every day at the glass factory.

Written by scienceguy