CO2 Neutral Glass Manufacturing? – A Study of the Possibilities

The technological needs to achieve CO2 neutrality during glass manufacturing have been investigated by theoretical calculations on energy balances and experimental investigations on batch reactivity and fining efficiency. The concept is based on the assumption of utilization of woody bio fuel combustion directly over the batch blanket and glass melt bath for heating the glass furnace. Energy balance calculations were made for a “hot top”, 50 tonnes per day continuous furnace. Furthermore, elimination of the chemically bound CO2 in the glass batch has been considered by investigating the possible substitution of the batch carbonates by other compounds not bearing chemically bound CO2. Compounds not emitting oxides of carbon, nitrogen or sulphur were considered as candidate batch components. Studies on the effect of batch melting and fining indicate a beneficial effect on energy efficiency and melting rate when using carbonate substitutes. It is concluded that the combustion concept is theoretically fully possible for glass tank application. The substitution of batch carbonates by non carbon compounds is questionable from an environmental point view since the alternatives are expected to be synthesized by routes emitting CO2.