Shaping a Greener Future: Navigating the Path to Low-Carbon Glass – Part 5

In our previous Industry Perspective paper, we explored various technological pathways for producing decarbonized glass. While full electrification is often presented as the ultimate solution, it comes with significant challenges, including energy storage constraints and limited tolerance for prolonged energy disruptions in continuous glassmaking. Additionally, all-electric melters tend to be less adaptable than traditional natural gas-based furnaces, more sensitive to pull rate variations, and less effective at melting darker glasses due to fundamental physical constraints.

Given these limitations, we now examine alternative solutions. Hydrogen, for example, can be stored either as a cryogenic liquid at -253°C or compressed at 700 bar. However, both hydrogen combustion and, although less, electrification require substantial energy input, creating challenges for both the external power grid ("outside the fence") and on-site energy management ("within the fence").

Green hydrogen is not naturally occurring and must be generated through electrolysis, which has a theoretical maximum efficiency of 80%. However, when factoring in combustion efficiency, the total energy efficiency from source to melted product rarely exceeds 30%. Moreover, producing and delivering hydrogen requires roughly three times more installed electrical power than state-of-the-art electrical heating. Given these inefficiencies, hydrogen's role in glass manufacturing is likely to be limited, primarily as “boosting” or a backup to manage intermittency.

So, what is the best approach—full electrification or hydrogen? Each has distinct advantages and drawbacks. Should the glass industry prioritize all-electric solutions despite their operational constraints, or further explore hydrogen, despite its inefficiencies and supply challenges? Or, perhaps a hybrid approach, integrating both technologies, offers the most balanced and efficient path forward?

Could Green Hydrogen Replace Natural Gas in Glassmaking?

A key question emerges: Is there an easier or more viable route to decarbonization? While electrification is often cited as the primary solution, hydrogen is another frequently discussed alternative. However, not all hydrogen is created equal. The industry differentiates between green, blue, grey, black, turquoise, yellow, and pink hydrogen. For long-term sustainability, only green (produced via renewable-powered electrolysis) and yellow (electrolysis powered by nuclear energy) seem attractive options.

Blue and purple hydrogen, while often positioned as transitional solutions, are not truly decarbonized and carry risks—particularly with nuclear-powered production. However, the biggest drawback of both green and yellow hydrogen is their low overall energy efficiency in combustion applications. As noted earlier, less than 30% of the initial energy input ultimately reaches the melting process.

Additional challenges associated with hydrogen combustion include:

• Invisible flames, which complicate risk management.
• Increased NOx emissions due to higher combustion temperatures.
• Elevated water vapor (H?O) content in the combustion space, potentially affecting furnace performance.
• Safety concerns related to hydrogen’s unique combustion properties.

In practical terms, an industry-wide transition to hydrogen-fired furnaces is far from straightforward. Existing gas-fired furnaces cannot simply switch from natural gas or oil to hydrogen. Entirely new burner technologies must be developed for hydrogen-oxygen combustion, necessitating a redesign of flow control systems and combustion processes.

Key Technical Challenges of Hydrogen Combustion

1. Flame Characteristics?– Hydrogen burns with a higher flame speed and across a wider combustion range, making precise control more difficult.
2. Combustion Sensitivity?– Unlike natural gas, hydrogen can combust with both higher and lower concentrations of air, increasing safety risks and control complexity.
3. Molecular Size and Leakage Risks?– Hydrogen’s small molecular size allows it to leak through seals and cracks that would typically contain methane or other hydrocarbons.
4. Material Selection & NOx Emissions?– Hydrogen’s higher combustion temperature necessitates careful material selection for furnace components and results in increased NOx formation.
5. Energy Density & Volume Constraints?– Hydrogen has a lower energy density per unit volume than natural gas, requiring significantly greater storage and transport infrastructure to deliver the same heating value.

Conclusion

While hydrogen presents an interesting alternative fuel source, its low efficiency, supply challenges, and the extensive infrastructure modifications required make it an unlikely primary solution for large-scale glass manufacturing. Instead, full electrification appears to be the most viable long-term pathway. However, a hybrid approach integrating both technologies strategically—using hydrogen to mitigate intermittency in electric systems—could provide a more practical transition toward low-carbon glass production.

In one of the next parts of this series, we will explore ammonia: In the pursuit of decarbonizing glass manufacturing, alternative fuels are under the spotlight. In this next article, we explore ammonia—not just as a bold contender, but as a complex proposition. Can it truly fuel the future of glass melting, or does its promise rest on fragile foundations?

As a leader in energy management and industrial automation, Schneider Electric is committed to delivering innovative solutions that support the glass industry’s transition to a sustainable, low-carbon future. Beyond optimizing energy efficiency and process electrification, Schneider Electric actively contributes to the advancement of hydrogen technologies, offering cutting-edge power conversion systems and smart automation solutions that enhance hydrogen integration in industrial processes. By leveraging advanced digital tools, smart automation, and expertise in hydrogen infrastructure, Schneider Electric empowers manufacturers to maximize efficiency, minimize emissions, and drive the industry toward a greener tomorrow.

End of part 4

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Keep an eye out for the next edition in this Industry Perspectives series, where we’ll delve deeper into the future of glass melting technology.