Analyzing the future potential of defossilizing industrial specialty glass production with hydrogen by LCA

Abstract

The glass industry is part of the energy-intensive industry, with most of the energy needed to melt the raw materials. To produce glass, temperatures between 1000 and 1600 °C are necessary. Presently, mostly fossil natural gas is the dominant energy source. As direct electrification is not always possible, in this paper a Life Cycle Assessment (LCA) for specialty glass production is conducted, where the conventional fossil-based reference process is compared to a hydrogen-fired furnace. This hydrogen can be produced on-site in an water electrolyzer, using not only the hydrogen for the combustion but also the produced oxygen. Hydrogen can be produced alternatively off-site in a large scale electrolyzer to facilitate economy of scale. For the transport and distribution of this hydrogen different options are available. A rather new option are liquid organic hydrogen carriers (LOHC), which bind the hydrogen in a chemical substance. However, temperatures around 300 °C are necessary to separate the hydrogen from the LOHC after transport. At the glass trough waste heat is available at the required temperature level to facilitate the dehydrogenation. The comparison is completed by the production of off-site hydrogen transported to the glass trough as conventional liquefied hydrogen in cooling tanks by truck or in hydrogen pipelines.In this assessment, to power the electrolyzers the national grid mix of Germany is used. A time frame from 2020 till 2050 and its changing energy system towards defossilisation is analyzed. Regarding climate change, on-site hydrogen production causes the least impact for specialty glass production in 2050. However, negative trade-offs for other environmental impact categories, e.g. Metal depletion, are recorded.