(Mainz) – The glass manufacturer Schott AG tested the melting of three different glasses using hydrogen at its Mainz factory for eight weeks. Result: When firing with hydrogen and oxygen, a similar burner output and temperatures could be achieved as with the conventional process using natural gas and oxygen. The quality of the glass produced was also similar to that of conventional glass.
It was not clear from the start that this would work. Natural gas cannot simply be exchanged for hydrogen, according to the report from the Copernicus project “P2X”, funded by the Federal Ministry of Education and Research, as part of which the tests took place. Both gases burn with different reactions. In order for hydrogen to actually be used to melt glass, it must be used “in such a way that it emits the same heat radiation as natural gas.” In addition, completely new systems are needed to transport the hydrogen to the glassworks and from there to the melting plant. The transport is, at least currently, significantly more complicated than that of natural gas.
Until now, it was not clear to what extent the water vapor produced by the combustion of hydrogen influences the chemical composition of the glass. The first results definitely showed water vapor-related changes in the glass properties compared to the conventional manufacturing process.
In the next step, the researchers will examine the process steps necessary to control glass quality in special glass production. At the same time, further work was underway to set up a complete supply infrastructure and a concept for hydrogen supply, it is said. “The aim of P2X is to transfer the results to the entire glass production chain and to transfer the heating process to a larger scale.”
According to information, one in five glasses sold in the EU is made in Germany. In order to fuse quartz sand, lime and soda into glass, temperatures of around 1.600 degrees Celsius are required. To achieve this, melting tanks powered by natural gas have previously been used. For around seven million tons of salable glass each year, five million tons of CO2 emissions are generated - these must be avoided.
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Glass melting furnace from Schott AG / © Alexander Sell, Schott AG
