1 tonne of cullet saves 1.2 tonnes of raw materials. Cullet allows to save a significant amount of melting energy. An increase with 10% more cullet means saving 2,5% of energy consumption. That means a strong decrease of CO2 emission is possible thanks to cullet recycling. Recycling of 1 tonne of cullet allows to avoid the emission of 700 kg of CO2.
The average cullet ratio in our raw materials is close to 30% today, but this will be increased significantly.
Closed loop recycling
To achieve the objectives for flat glass in a climate-neutral Europe, a greater input of cullet is identified as one of the major routes to reduce CO2 emissions from manufacturing.
It is therefore in our, and in the common interest of the flat glass industry, that an increased quantity of cullet returns to the flat glass industry in a closed-loop model, i.e. ‘flat glass to flat glass’.
The sector sets the goal to promote close loop “flat glass to flat glass recycling” and no other forms of recycling (to other glass sectors) or downcycling. Secondly, the stakes are around the availability / quantity of cullet. The issue of cullet specifications is left aside because any cullet collection must be of a certain quality to ensure a closed loop recycling is made possible.
Three routes of recycling flat glass cullet
In cullet we distinguish 3 types of routes: internal cullet (cullet at the glass production site), Pre-consumer cullet (cullet occurring at customers’ sites during glass processing) and End-of-Life cullet (cullet generated at the end of life of the glazing product)
There is an estimated +/-5 Mt of flat glass cullet available annually in the EU. The flat glass sector stands ready to use the available cullet, if uncontaminated, to further sustain its production, and reduce CO2 emissions from manufacturing.
AGC is actively involved in several projects to improve collection and reuse of cullet in our plants, such as:
- redefining the flows of cullet in order to reduce transport distances between the source, the recycler and the float plants,
- teaching our people to sort the cullet efficiently to recycle it better,
- increasing the range of materials that we can load into our furnaces.
However, the cullet used in our own production process must meet stringent specifications, and so we also actively seek out alternative routes for cullet that we cannot recycle in our own products.
Today the clean cullet that can be used in float glass furnaces represents only 8.5 per cent* of all the cullet collected after the use phase of existing glass because we need to know the exact composition of the cullet and make sure it is uncontaminated, that means not mixed with other materials.
The challenge of collecting End-of-Life flat glass
When it comes to end-of-life glass stream, there is a difference between cullet from automotive glazing and from building glass. Within building glass, there is a difference between commercial, and residential glazing.
With the renovation wave of buildings at hand, a huge potential of cullet volumes sits in existing buildings
In the Netherlands AGC helped to develop a national system of collection of flat glass from construction and demolition waste. Vlakglas Recycling Nederland (VRN) makes sure flat glass containers are available across the country to collect cullet. The system is financed through a tax on every m2 of insulated glass produced or imported in the Netherlands.
Cullet output is then sold by VRN. Initially main clients were glass container, glass wool and glass treatment companies. New agreements have been put in place to sell greater quantities to flat glass manufacturers. This cullet is now also sold to AGC furnaces..
However, a great part is not clean enough for float production and is reused in other glass production (for bottles, fiberglass, foam glass, etc.), but there are many other potential uses such as reflective road surfacing, golf bunker sand, aquarium ornamentation, water filtration systems, construction aggregates.
Recycling other types of waste
Depending on the activities, various types of waste are produced by our plants. These include used refractories, sludge from wastewater treatment systems, waste oil from maintenance, ordinary trash from administration activities, etc. In line with the objective of avoiding landfill, for each production site we have implemented a progressive approach based on prevention, reuse, recycling, and incineration.
We have succeeded in recycling other types of waste in addition to glass cullet. For instance, most of the recycled sludge coming from wastewater treatment is now recycled in cement production.
