Glass is a fundamental and necessary material to meet the challenges of the energy transition (manufacture of solar panels, textile fibers for wind turbines, insulation, etc.). Glass is therefore a multifaceted material, necessary for the construction of tomorrow’s world, which must be manufactured in a virtuous manner, emitting as little greenhouse gas as possible.
Almost all glasses are manufactured in gas furnaces that produce large quantities of CO2. Gas furnaces have several advantages: they can be used for decades; they offer great operating flexibility, allowing the volume of glass produced each day to vary; they allow the temperature to be adjusted according to the nature of the raw materials, but also to the redox state of the silicate batch. It is indeed relatively easy to intervene on the gas mixture and to regulate the quantity of oxygen available, fO2, at fusion.
But the current energy context and the roadmaps of the ecological and sustainable transition demand important modifications of the melting and working processes in the medium term and for all sectors of the glass industry. Glass producers are aware of energy efficiency issues. But drastic changes are needed to develop energy efficient furnaces. Several ways are possible:
– increasing the amount of hydrogen in the gas mixture, but what will be the implications on the redox of the silicate bath,
– the use of electric furnaces but how to control the redox
– the search for new raw materials by increasing the proportion of cullet and, above all, the abandonment of the use of carbonates and the search for substitutes for their use.
We will review all these scenarii.