#insights

In our planet, we generate around 51,000 million tons of greenhouse gases every year, of which approximately 36,400 million are related to energy generation, according to data published by the IEA in 2022. Of these, 7,500 million tons, almost 15% of total emissions, derive from natural gas combustion, which is the main fuel used in various industries, such as the glass sector.

The commitment undertaken by the United Nations in the Paris Agreement (2015) establishes a reduction in greenhouse gas emissions by 45% in 2030 and achieving zero emissions in 2050. Considering the glass sector’s inertia, in which the average lifespan of a glass furnace is between 12 and 15 years, we need to start developing technology that enables this transition within the set deadlines.

At present, the main energy carrier considered for this replacement is hydrogen, as we have the technology to generate it (electrolysis) and because water is generated in its subsequent combustion, which is an environmentally harmless substance. However, there are several challenges associated with working with this substance.

Hydrogen takes the form of gas at temperatures above -423ºF, and in ambient conditions it has a density of 0.09 kg/m3. Therefore, although its combustion per kg produces three times more energy than natural gas, we need to check upwards the flow rate fed to the furnaces to maintain the same output of the burners, given its low density at ambient temperature. In addition, its combustion rate is 7 times higher than that of natural gas, and it generates a higher flame temperature, which in normal circumstances increases the proportion of NOx gases (nitrogen oxides) when the combustion is carried out with air, due to its nitrogen content, and these are highly polluting substances.

There are various properties of the combustion process, like those already mentioned, that in glass melting furnaces are altered by this replacement and, therefore, must be cared about in detail. We must analyze the following aspects to reduce or eliminate its impact:

• The design of the burners, to achieve a homogeneous temperature in the entire furnace or minimize the generation of NOx gases.
• Modifications to the supply and discharge of exhaust gases inside the furnace, with the aim of removing the water produced by the chemical reaction of hydrogen combustion.
• The furnaces’ geometry, to obtain glass with the desired quality.
• The materials of which the hydrogen transport pipes are made, due to the embrittlement produced by hydrogen in certain materials.
• The behavior of the melted glass inside the furnace, as it will be in contact with water molecules and the burners on the surface and with the insulating material on the bottom.

Last but not least, in terms of safety, we must take into account that hydrogen’s ignition energy is 14 times lower than natural gas, which means a higher risk of ignition. In addition, hydrogen molecules are very small, making them much harder to confine. Therefore, implementing this gas as a new energy carrier involves reviewing not only the equipment’s design and their integration, but also all the safety protocols associated with its handling.

These obstacles can be overcome by promoting an interdisciplinary collaboration between engineers, scientists, technologists, and industry leaders, with the aim of driving projects that enable in-depth research and the development of feasible and affordable solutions.

The H2Glass project was conceived with the spirit of addressing challenges in the glass and aluminum sector. It brings together 23 strategic partners in Europe to develop the technology required to implement hydrogen in a relatively short time of four years. During this period, five companies in the glass sector, involved in its different formats of containers, fiberglass, and sheet glass, will try to tackle this problem in order to facilitate the transition to the EU’s zero emissions target by 2050. The aim is that these solutions can be transferred to other industries.

In this context, investment in R&D and the commitment to long-term projects are fundamental pillars. Only by joining knowledge, resources and viewpoints from various fields will we be able to forge a path towards a more sustainable future for industry and society.