Because it requires large amounts of heat, glass production is one of the most energy-intensive industries in the world. Alternatives to the combustion of natural gas are considered in this article.
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As with other energy-intensive processes, commercial glass production is quality sensitive, capital intensive and cost competitive. In the past, the industry depended on fuel oil as its primary source of energy, but most modern operations now use natural gas.
Massive amounts of heat are needed to melt the raw materials so that they can be made into glass. After the raw materials are melted and refined, the liquid glass is transformed into end products such as window panes or bottles. The production of any amount of heat is based on the product being produced.
In some operations, natural gas heat is supplemented by electrical heat and heat from other fuel sources, but the industry relies heavily on natural gas. Electric heating is used on a small scale and some production systems use electric heating methods to improve quality and productivity.
Why relying on natural gas is risky
As seen with other non-renewable energy sources, an industry dependent on natural gas results in a number of very serious risks.
On the one hand, the price of natural gas can fluctuate considerably and increase sharply in times of crisis. The COVID-19 pandemic triggered a number of factors that appeared to have pushed up the price of natural gas.
On top of that, demand for natural gas has increased in Asia and gas supplies from Russia have been tighter than usual.
As a result, Europeans have seen their natural gas prices increase by over 200% while some Asian countries have seen an increase of over 150%. Meanwhile, U.S. natural gas prices have risen 100% since the start of 2021.
There are also a number of environmental risks associated with dependence on natural gas, as the combustion of this fossil fuel releases massive amounts of carbon. For example, the flat glass and container segments of the industry, which account for around 80% of global glass production, released around 18 million metric tonnes of carbon dioxide in 2019.
Solutions are explored
There are a number of opportunities to reduce energy consumption in the glass production industry, which would result in reduced combustion of natural gas. For example, improving smelting and refining processes could potentially reduce energy consumption by 20-25%. Improvements in other areas of commercial production could also have an impact, and these would be product-specific refinements.
Although there appear to be a number of interesting possibilities, there is currently no commercially viable way to eliminate the use of natural gas in the production of glass.
One possible solution is the use of gaseous hydrogen, a renewable resource, instead of natural gas. The main problem with burning hydrogen is that it requires more gas to get the same amount of heat output as natural gas. Researchers are currently studying ways to increase the radiative qualities of hydrogen to make it a more viable alternative to natural gas.
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Biofuels are another category of alternative fuels that could potentially replace natural gas.
Currently available biofuels produce a more radiant flame and higher heat transfer during combustion. Biodiesel is a promising type of biofuel that can be made entirely from renewable sources.
While biodiesel has been used as an additive in traditional diesel fuel for the transportation industry, the glass production industry has yet to explore this option, let alone a fully biodiesel-fueled oven.
Many glass production operations efficiently use electrical heat instead of heat produced directly by natural gas. In addition, any electric heater has been found to be much more energy efficient than natural gas heater.
Unfortunately, the complete electrification of the glass production industry requires new technological developments in furnace technology, especially when it comes to adapting the capabilities of modern large capacity furnaces.
Economic viability is also a concern, as capital expenditures related to electrification are significant. Additional infrastructure would also be needed.
For now, researchers are considering the possibility that hybrid systems could not only bridge the gap to a natural gas-free future, but also protect an operation from spikes in material costs and supply chain issues.
For example, a gas-electric hybrid could be converted to biodiesel-electric operations or 100% electric heating depending on need and practicality. The possible hybrid use of electricity could also lend itself to future smart grid systems.
References and further reading
US Department of Energy. (2021). Glass manufacturing is an energy intensive industry primarily fueled by natural gas. [Online] Available at: https://www.eia.gov/todayinenergy/detail.php?id=12631
Sharafedin, B. et al. (2021). Soaring gas prices are spilling over into heavy industry and supply chains. Reuters. [Online] Available at: https://www.reuters.com/business/energy/soaring-gas-prices-ripple-through-heavy-industry-supply-chains-2021-09-22/
Zier, M. et al. (2021). A review of decarbonization options for the glass industry. Energy conversion and management: X. [Online] Available at: https://www.sciencedirect.com/science/article/pii/S2590174521000088
Ireson, R. et al. (2019). Alternative fuel switching technologies for the glass industry. UK Department for Business, Energy and Industrial Strategy. [Online] Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/866364/Phase_2_-_Glass_Futures_-_Fuel_Switching_Tech_for_Glass_Sector.pdf